Glossary of technical terms for the use of metallurgical engineers Terms starting with alphabet ‘S’
Glossary of technical terms for the use of metallurgical engineers
Terms starting with alphabet ‘S’
Sach’s method – It is a technique for the measurement of axisymmetric residual stresses from the analysis of strain relaxations during the incremental removal of layers of material from an axisymmetric component.
Sachsse-Bartholome process – It is also known as the BASF process. It is a method for producing acetylene from natural gas or other hydrocarbons. It involves the partial oxidation of the hydrocarbon feedstock, typically natural gas, in a burner using oxygen, leading to the formation of acetylene. The key features include a high reaction temperature, partial oxidation, and rapid cooling of the cracked gas stream to prevent unwanted reactions.
Sacrificial anode – It is a type of corrosion protection method which utilizes a more reactive metal to protect a less reactive metal from corrosion. It acts as a ‘sacrificial’ element, corroding in place of the structure it is meant to protect. This technique is normally used in marine, offshore, and underground applications to extend the lifespan of metal structures like pipelines, tanks, and heat exchangers. These anodes are made of metals which are more reactive than the metal they are protecting. Common examples include zinc, magnesium, or aluminum.
Sacrificial anode method – It is a corrosion prevention technique where a more reactive metal (the sacrificial anode) is connected to a less reactive metal (the structure needing protection) to corrode preferentially, hence protecting the structure. This works by making the structure a cathode and the anode corrodes in its place. Common sacrificial anodes include zinc, magnesium, or aluminum alloys.
Sacrificial protection – It is the reduction of corrosion of a metal in an electrolyte by galvanically coupling it to a more anodic metal. It is a form of cathodic protection.
Sacrificial template method – It refers to a processing route for creating porous ceramics which relies on a dispersed phase, which leaves behind pores after its removal during sintering.
Saddle spall – It refers to the shedding of fragments, frequently in the shape of a saddle, from a material because of the impact or other damaging forces. This phenomenon is a type of spalling, which is the process where small pieces of a material are broken off. Saddle spall can occur in several materials like metal, stone, and even glass, and is a significant concern in applications where materials are subjected to high impact or stress.
Saddle – It is a casting, fabricated chair, or member used for the purpose of support. In conveyor, saddle is short length of belting added to an existing belt (mostly a replacement in case of partial damage or splice failure).
Saddle shaped fatigue spalls – These originate in the core material below the shell/core interface and break out to the barrel surface. Variable intensity of fatigue lines can be seen in the deep areas of the spall indicating the propagation direction from the core to the barrel surface. These spalls occur in work rolls with flake graphite iron core and are predominantly located in the centre of the barrel. Spalling is caused by high cyclic loads due to large reductions when rolling thin gauge and hard materials. These loads induce high alternating stresses on the core material, beyond the fatigue limit, and many micro cracks begin to form causing a progressive weakening of the core material. In the next stage these micro cracks join together and propagate to and through the shell to the barrel surface giving rise to the large and typical saddle spall. High residual tensile stresses which are thermally induced in the core during manufacture favour this type of roll damage.
Saddle support – It is a structural component, frequently used to support horizontal pressure vessels, which provides a cradle-like mechanism for the vessel’s weight distribution. These supports are designed to evenly distribute the weight of the vessel, minimizing stress concentrations and ensuring stability during operation and transportation.
Saddling – It means forming of a seamless metal ring by forging a pierced disk over a mandrel (or saddle).
Safe disposal – It is the process of getting rid of unwanted or hazardous materials, waste, or unwanted objects in a way which protects human health and the environment from harm, pollution, and contamination. This involves using methods such as proper collection, segregation, treatment, and final placement as per specific rules, regulations, and best practices for different types of waste, from everyday trash to specialized hazardous waste.
Safeguard principles – These are regulations which are used to restrain international trade in order to protect a certain indigenous industry from external competition.
Safeguards – It is a term which is used in the regulation of nuclear facilities and materials. The use of material control and accounting programmes is to verify that all special nuclear material is properly controlled and accounted for, and the physical protection equipment and security forces. As used by the International Atomic Energy Agency (IAEA), verifying that the ‘peaceful use’ commitments made in binding non-proliferation agreements, both bilateral and multilateral, are honoured.
Safe life – It is the number of cycles of deformation needed to bring about failures of the test sample under a given set of oscillating conditions (stresses or strains).
Safe operation – It refers to performing tasks, processes, or using equipment in a way which eliminates or minimizes risks, preventing harm to people, property, or the environment. It involves documented guidelines like safe operating procedures (SOPs) and adherence to regulations, ensuring tasks are performed consistently and correctly to maintain safety, quality, and efficiency.
Safe range – It is frequently called a proven acceptable range (PAR) or a normal operating range (NOR). It refers to the defined range of a parameter within which operation, while keeping other parameters constant, guarantees the production of a material meeting specified quality criteria. This means the process can consistently produce a product that meets the required quality attributes.
Safe system of work – It a method of working which eliminates or reduces the risk of injury.
Safety – It normally means protection of a worker from physical hazards. It consists of the maintenance of a work environment that is relatively free from actual or potential hazards which can injure employees.
Safety analysis – It is a documented process (i) to provide systematic identification of hazards within a given operation, (ii) to describe and analyze the adequacy of the measures taken to eliminate, control, or mitigate identified hazards, and (iii) to analyze and evaluate potential accidents and their associated risks.
Safety and health organization – It is the organization in the steel plant which promotes safety and health in the plant and deals with all the issue related to it. The organization consists of a safety-departments, safety committees, shop safety coordinators and occupational health or first aid centres.
Safety and health policy – It is a policy of statement of intent, and a commitment to plan for coordinated management action towards organization’s safety and health objectives.
Safety and shutdown systems – These are designed to provide a safeguard against catastrophic events such as explosions, fires, and other hazardous situations. These systems are activated when predefined safety conditions are breached, resulting in the immediate prevention of further risks. These systems are engineered to safeguard people, the environment, and assets by preventing or mitigating hazardous situations in industrial processes. These systems, which can include emergency shutdown systems (ESDs) or safety instrumented systems (SIS), are designed to shut down processes or equipment to prevent escalation of events leading to accidents.
Safety assessment – It is a systematic process of evaluating potential hazards and risks associated with a particular situation, process, or system to ensure safety and prevent accidents or injuries. It involves identifying potential dangers, analyzing their severity and likelihood, and implementing measures to mitigate those risks.
Safety at work-place – It means following of set of procedures, rules, and actions implemented to minimize hazards and protect employees from injuries, illnesses, and accidents in the work-place. These work-practices aim to create a safe environment where employees can perform their duties without undue risk to their physical, mental, or emotional well-being.
Safety audit – It is is a systematic and structured process of independent examination to determine the effectiveness of safety management system in the organization. It is a structured evaluation of the application and efficiency of the safety policy, safety programmes, and safety systems of the organization. It is also a control of the compliance with the regulatory regulations and a clear standard, which may be a national standard or organizational internal standard. An audit is a widely used instrument and an important tool to improve safety. It is the process of verification that the safety programmes are working. Broadly defined, an audit is a systematic review of operations and practices to ensure that relevant requirements are met. Safety audit applies several methodologies to mitigate safety risks within the organization. Safety audits evaluate all aspects of the safety programmes with special emphasis on the quality as well as the quantity of safety activities at every level. Safety audits are a managerial or a corporate activity.
Safety audits and safety inspections – These are the tools which an organization use for its preparedness towards safety. Safety audit involves systematically going through the work-place to evaluate safety programs and practices within the organization while safety inspection involves systematically going through the work-place to look for safety hazards or lapses in safety practices. Both are important components of a work-place safety plan. They are frequently used interchangeably though they are not the same.
Safety awareness – It is an important aspect of safety for taking care of hazards. It can be improved through the observance of safety day and safety week. Further, safety meetings are to be held regularly for all employees to reinforce safety awareness.
Safety belts – These are also known as safety harnesses. These are personal protective equipment designed to prevent falls from high work areas. They act as a crucial component of fall arrest systems, connecting a worker to a secure anchor point and minimizing the impact in case of a fall. Safety belts are typically used in conjunction with other safety equipment like lanyards and anchorage systems to create a comprehensive fall protection plan. For working at heights, it is necessary to adopt basic safety precautions including the provision of suitable working platforms, safe access and egress and the erection of suitable guardrails at hazardous locations. If these safety precautions are not feasible, safety belts are used. Common types of safety belts are (i) with full body harness to be used to prevent falls, and (ii) general purpose safety belt and its lanyard are to be used to restrict movement while working.
Safety case – It is a documented body of evidence which is submitted to regulators to provide a convincing and valid argument that a specified system is safe for a given application in a given context or environment.
Safety clothing – It is also known as protective clothing. It is specialized apparel designed to protect the wearer from a variety of hazards in the work-place or during recreational activities. These hazards can be physical, chemical, environmental, or biological, and the clothing aims to prevent injuries, illnesses, or exposure to harmful substances.
Safety committee – It is a committee representative of all employees with the objective of promoting co-operation in investigating, developing, and carrying out measures to ensure the health, safety and welfare of the employees. The organization is to establish central safety committee and departmental safety committees for the purpose of improving, promoting and reviewing all the matters relating to the safety of the employees. Safety committees need to have prescribed functions and responsibilities. The composition, functions, and duties of the safety committees are to meet the requirements of the Factories related regulations and acts. Matters discussed in the safety committees are to recorded adequately and communicated to the all concerned.
Safety concerns– These refer to the identification of a potential risk or hazard which can lead to harm, injury, damage, or negative consequences to a person, property, or the environment. These concerns highlight an existing or possible threat to well-being, needing attention, action, or further investigation to ensure a safe outcome.
Safety controls – These are measures implemented to reduce risks associated with hazards, protecting employees from injuries and illnesses. They are steps taken to prevent or minimize work-place hazards, ensuring a safe and healthy work environment. These controls are frequently structured in a hierarchy, prioritizing the most effective methods first.
Safety, controls, alarms, and interlocks (SCAI) – These are engineered safeguards used to prevent or mitigate hazardous events in industrial processes and equipment. They work together as layers of protection to reduce risk. Safety controls monitor and maintain process variables within safe operating ranges, alarms alert operators to abnormal conditions, and interlocks automatically shut down or isolate equipment when pre-defined safety limits are breached.
Safety culture – It is the assembly of characteristics and attitudes in the organization and its employees which establishes that, as an overriding priority, protection and safety issues receive the attention warranted by their significance. It can also be described as a product of the individual and group values, attitudes, competencies and patterns of behaviour which determine the commitment to, and the style and proficiency of the organizational health and safety programmes.
Safety deviation – It is an action which can endanger a person or people working around him or any situation judged as being such that, sooner or later, it can lead to a risk of an incident inflicting harm to one or more persons.
Safety data sheet (SDS) – It is material safety data sheet (MSDS). It is a standardized document created by the manufacturer or importer of a hazardous chemical to communicate essential safety and health information. It details the chemical’s physical properties, hazards, safe handling procedures, emergency measures for spills or exposure, needed personal protective equipment (PPE), and proper storage and disposal. Safety data sheets are important for informing employees and assisting emergency services, making them a crucial tool for ensuring work-place safety and responsible chemical management.
Safety engineers – Safety engineers are professionals who ensure the safety of work-places and products by developing and implementing safety protocols, assessing risks, and designing systems to prevent accidents and injuries. They work to minimize hazards associated with human error, machinery, chemicals, and other potential dangers.
Safety engineering – It is an engineering discipline which assures that engineered systems provide acceptable levels of safety. It is strongly related to industrial engineering / systems engineering, and the subset system safety engineering. Safety engineering assures that a life-critical system behaves as needed, even when components fail. Analysis techniques can be split into two categories namely qualitative methods and quantitative methods. Both approaches share the goal of finding causal dependencies between a hazard on system level and failures of individual components. Qualitative approaches focus on the question ‘What must go wrong, such that a system hazard may occur?’, while quantitative methods aim at providing estimations about probabilities, rates and / or severity of consequences.
Safety environment and equipment protection – It refers to safeguarding the environment from pollution and degradation, while equipment protection focuses on ensuring the proper use and maintenance of safety equipment to prevent harm and accidents. It is about creating a safe working environment and using the right tools to protect workers and the surroundings from hazards.
Safety equipment – It refers to protective gear and tools which employees use to protect themselves from harm and prevent accidents while on the job.
Safety factor – Published capacity of the lifting magnet represents ultimate lift strength i.e. the lifting capacity of the magnet on different loads ‘under ideal conditions’ unless clearly specified otherwise. It is normally impossible to foresee all the varying conditions of operation from one installation to another and to try to rate the magnet for each and every possible condition of operation. Instead, the magnet capacity is specified by applying a ‘safety factor’ to the ultimate lift strength of the magnet, making sure that the safety factor applied represents actual conditions as far as practical. Some of the operating conditions which dictate the applicable safety factor are (i) surface condition of the load, (ii) surface condition of the magnet, (iii) smoothness of the lift, (iv) flatness and stiffness of the load, (v) centering of the load on magnet, (vi) environment, (vii) voltage fluctuations (for electromagnets), and (viii) unknown conditions. When any of these conditions are something which is not ideal then a safety factor is applied for the ultimate lift strength. This safety factor is to take into account the corresponding adverse effects on the ultimate lift strength of the magnets. In a conveyor, safety factor is a multiplier applied to the calculated maximum force to which a conveyor belt splice (as the weakest link in a conveyor belt) is to be subjected. A factor of safety accounts for imperfections in materials, flaws in assembly, material degradation, and other uncertainties. Conventional safety factors normally range from 6,7 to 10 for steady operating conditions, related to the splice strength.
Safety fence – It is a physical barrier or enclosure designed to prevent unauthorized access to hazardous areas or to protect people, pets, and property from potential harm. These barriers are used across different settings, from construction sites and industrial machinery to hazardous zones, to keep people out of danger, manage traffic, or comply with safety regulations.
Safety function – It is a specific purpose which is to be accomplished for safety for a facility or activity to prevent or to mitigate the unsafe consequences of normal operation, anticipated operational occurrences, and accident conditions.
Safety glass – It is the glass which does not disintegrate into sharp and potentially dangerous splinters when it is broken. Safety glass can be produced by laminating or by tempering.
Safety glasses – These glasses have safety frames constructed of metal or plastic and impact-resistant lenses. Side shields are available on some models. Safety glasses are not to be used for protection against chemical splashes, mists or vapours.
Safety guidelines – These are instructions and recommendations designed to prevent accidents, injuries, and damage to property, ensuring the well-being of individuals and minimizing risks. These guidelines cover a wide range of activities, from workplace practices to everyday actions, and can be formal rules or informal best practices.
Safety improvement teams – These are constituted in every department consisting of 5 workmen to 8 workmen per team. These are established to work on specific projects for improvement in the work environment and safety of the work-men, equipment and processes. These safety improvement teams are to get support from the management in the form of recognition, incentives and rewards.
Safety instrumented function (SIF) – It is a safety-related function which automatically brings a process to a safe state when a hazardous condition is detected. It is a critical component of a safety instrumented system (SIS) and is designed to prevent or mitigate hazardous events.
Safety instrumented system (SIS) – It is a system designed to automatically bring a process to a safe state when predefined conditions are violated. It consists of sensors, logic solvers, and final control elements to monitor process parameters and, if necessary, take action to prevent or mitigate hazards. Safety instrumented system is a critical safety layer in industrial processes, particularly in areas like chemical plants, refineries, and other industries with potential hazards.
Safety harness – It is personal protective equipment (PPE) which is designed to prevent falls and injuries when working at heights or in other hazardous environments. It consists of a system of straps which secure around the body, distributing the forces of a fall and connecting the user to a secure anchor. Harnesses are crucial for fall protection, especially in construction and other industries where work at heights is common.
Safety helmet – It is personal protective equipment (PPE) which is designed to protect the head from injury in a work-place or other hazardous environment. It shields against impacts from falling objects, blows to the head, electrical hazards, and other potential dangers.
Safety inspection – It is defined as that monitoring function which is conducted in an organization to identify, locate and report existing and potential hazards which can cause accidents in the work-place. Safety inspections frequently reveal potential causes of accidents and, hence, provide an opportunity to take corrective action before an injury occurs. Safety inspections are conducted at the line or operating levels and are an important part of the overall safety programme. Safety inspections look at the physical conditions and work practices in a work-place. Equipments are examined to determine whether all safeguards are in place and whether its operation presents any hazards. Air, water, and other samples can be obtained to test for hazardous substances. Work practices are observed to identify unsafe actions. Safety inspections are effective ways of preventing accidents. However, it is essential to take corrective action as soon as possible to abate all hazards found during a safety inspection. If the hazard presents an imminent danger to employees, the corrective action is to be taken immediately. For any reason, if the corrective actions are delayed for non-imminent hazards, then it is necessary to document the reason for the delay and the estimated date of correction. When the corrective action has been completed, then the action date needs to be documented.
Safety inspectorate – It is the statutory authority with the task of advising and giving directions on issues concerning the protection of workers and the work environment, as well as checking that the protection is sufficient.
Safety instructions – These are detailed guidelines which outline specific procedures and protocols to ensure the health and safety of individuals in a given environment or task. They aim to prevent accidents, injuries, or damage by providing clear instructions on how to handle equipment, perform tasks, and react to emergencies.
Safety issues – These are deviations from current safety standards or practices, or weaknesses in facility design or practices as identified by plant events, with a potential impact on safety because of their impact on defense in depth, safety margins, or safety culture.
Safety layers – These are passive systems, automatically or manually initiated safety systems, or administrative controls which are provided to ensure that the required safety functions are achieved.
Safety limits – These are limits on operational parameters within which an authorized facility has been shown to be safe. Safety limits are operational limits and conditions beyond those for normal operation.
Safety management system (SMS) – It is a systematic approach to managing safety, including the necessary organizational structures, accountabilities, policies and procedures. It is a systematic and explicit approach in the organization defining safety activities by which safety management is undertaken by the organizational management in order to achieve acceptable safety levels. It is a term used to refer to a comprehensive management system designed to manage the safety elements in the work-place. It is a systematic approach designed to identify safety hazards and risks, control all safety elements and reduce the risks to a more acceptable manner by ensuring that the controls are effective. It is defined as ‘a businesslike approach to safety’. It is a systematic, explicit and comprehensive process for managing safety risks. As with all management systems, a safety management system provides a way for setting goals, planning, measuring the performance, control documentation and continues improvement. It becomes part of the culture, the way people do their jobs. Safety management system promotes a strong safety culture for achieving high standards of safety performance in the organization.
Safety manual – It is a document which outlines policies, procedures, and guidelines for maintaining a safe working environment. It details how to identify hazards, assess risks, and implement control measures to prevent accidents and injuries. The manual serves as a reference for all employees, ensuring they understand their responsibilities in maintaining a safe work-place.
Safety measure – These measures are practices and provisions which improve the working conditions for employees, protect their physical well-being, and reduce the risk of accidents in industrial settings. They encompass training, equipment installation, and adherence to regulations to foster a safety-conscious environment.
Safety monitoring – It is the periodic checks on observance of corporate safety standards and procedures.
Safety policy – The safety policy is to be simple and understandable. It is the declaration of the commitment to the safety by the organization. It serves as the foundation for the organizational SMS and provides a unifying vision of the safety concerns by the entire organization. It serves as the framework for setting objectives and targets and for planning and action. It drives the commitment of the organization to maintain and potentially improve its safety performance. The safety policy is to be supported by the senior management and understood by all the employees.
Safety practices – These practices refer to the set of procedures, rules, and actions implemented to minimize hazards and protect employees from injuries, illnesses, and accidents in the work-place. These practices aim to create a safe environment where employees can perform their duties without undue risk to their physical, mental, or emotional well-being. Key components of safety practices include (i) hazard identification and assessment, (ii) risk mitigation, (iii) training and education, (iv) emergency preparedness and procedures, (v) regular Inspections and maintenance, (vi) reporting and investigation, (vii) compliance with regulations, and (viii) promoting a safety culture.
Safety precaution – It is a measure taken before-hand to prevent harm or ensure safety. It involves taking actions to minimize potential risks or hazards, ensuring a safer environment or situation.
Safety procedures – These are established guidelines and protocols which are designed to ensure the well-being and physical safety of individuals in a work-place by outlining specific steps and actions to minimize risks and prevent accidents, injuries, and occupational hazards.
Safety professional (or safety engineer) – Safety professional is a person whose basic job function and responsibility is to prevent accidents and other harmful exposures and the personal injury, disease or property damage which can ensue.
Safety promotion – An organization is to develop work men to take interest in safety and is also to maintain safety awareness amongst the work-men to instill a positive attitude and behaviour towards safety at the work-place. Also, there is always a need to create a caring safety culture in the organization. Under safety management system, the organizational management is to develop and establish promotional programs that clearly demonstrate the strong commitment of the organization towards providing and maintaining a safe and healthy work environment. The promotional activities are to be organized at regular intervals. All employees including contractors are to be encouraged to take part in the safety promotional events.
Safety pull cord – It is an emergency stop device featuring a cord which, when pulled, triggers an immediate shutdown of the conveyor system. Regular inspections are necessary to ensure proper installation, tension, and responsiveness of safety pull cords.
Safety regulations – These are rules and guidelines designed to protect people from harm or injury in different environments. They aim to minimize risks and prevent accidents, injuries, and illnesses in work-places, and different settings. These regulations can be established by government agencies, industry standards organizations, or individual organizations.
Safety requirements – These are specifications or rules designed to prevent harm, injury, or damage to people, property, or the environment. They define the conditions which are to be met to ensure an acceptable level of safety for a system, product, or activity. These requirements can be related to design, operation, maintenance, and emergency procedures.
Safety risk assessment – It is the process of identifying or quantifying the extent of risk associated with an activity or material, which leads to decisions about how to manage those risks effectively. It involves a reasoned judgment about potential hazards, the likelihood of harm, and the consequences for individuals, ultimately resulting in a plan to mitigate risks to health and safety.
Safety risk management (SRM) – It is the assessment and mitigation of safety risks associated with hazards which threaten an organization’s capabilities, aiming to reduce these risks to a level as low as reasonably practicable (ALARP). It serves as a key component of the safety management process by facilitating a balanced allocation of resources among assessed safety risks.
Safety rod – It is a control rod which is used to decrease the reactor reactivity in the case of emergencies.
Safety shoes – These shoes are personal protective equipment for foot protection at work-places.
They prevent foot injuries caused by heavy objects, sharp piercing edges, pinch points, hot objects, splinters, chemicals, and electricity. Proper safety shoes can also help prevent falls because of slippery surfaces and keep the feet warm in cold weather. Safety shoes are designed to safeguard feet from several work-place hazards like impact, compression, and puncture, frequently featuring reinforced toe caps and slip-resistant soles.
Safety shut-off valve – It is a manually opened, electrically latched, electrically operated safety shut-off valve designed to automatically shut off fuel when de-energized.
Safety snap – It provides a quick and secure way to connect any two pieces of hanging equipment. The self-closing gate prevents the snaps from opening by accident or under pressure of heavy load.
Safety standard – It is a set of established regulations, rules, or guidelines designed to ensure the safety and well-being of people, equipment, and the environment by preventing harm and minimizing risks. These standards are developed by regulatory bodies, industry groups, or companies and are applied to products, processes, activities, and work-places to prevent accidents and injuries.
Safety switch – It is a switch which is integrated into a conveyor system to ensure safety by halting or controlling the operation when activated. Ongoing checks are essential to verify proper functioning, alignment, and responsiveness of safety switches.
Safety task – It is the sensing of one or more variables indicative of a specific postulated initiating event, the signal processing, the initiation and completion of the safety actions required to prevent the limits specified in the design basis from being exceeded, and the initiation and completion of certain services of the safety system support features.
Safety training – It is structured training programmes meant for the training of employees regarding different aspects of safety. Training is an essential part of an effective safety system. All employees are required to have the necessary training, skills and tools to do their job safely. Safety training is one of the ways in which competence and personal motivation towards safety can be taken forward. It has a unique role to play, which helps the organizational culture to change into a safety-oriented culture. In a safety-oriented culture, besides pure safety training, safety related issues also get included in the all the training areas. Safety training includes information about hazards, safe methods of work, avoidance of risks, and the use of personal protective equipment.
Safety valve – It is a device which automatically opens and releases excess pressure from a system when it exceeds a pre-determined level, preventing catastrophic damage. It is a crucial safety mechanism in several applications, particularly in industrial settings, acting as a fail-safe to protect equipment, personnel, and the environment. The valves which come under the category of safety valves are (i) pressure relief valve, (ii) steam traps, and (iii) other safety valves consisting of ‘rupture disc’ and ‘pressure vacuum valves’. In a boiler, safety valve is a spring-loaded valve which automatically opens when pressure attains the valve setting. It is used to prevent excessive pressure from building up in a boiler.
Safe working load (SWL) – It refers to the maximum load a piece of lifting equipment or a structure can safely handle without risking failure under normal operating conditions. It’s a crucial safety measure in industries that handle heavy loads, like construction and manufacturing, to prevent accidents and injuries.
Safe working pressure – It is the maximum permissible pressure at which a steam boiler can be operated.
Safe and healthy work-place environment – It is an essential condition for the safety of the workers as well as for the safe operation of the plant. Safe and healthy workplace environments are always the most efficient. In fact, the two go hand in hand. Work-place environment mainly consists of three components. These components are (i) technological process which takes place at the workplace, (ii) operating equipment at the workplace, and (iii) housekeeping and cleanliness at the workplace. These three components need proper and adequate controls for ensuring safety at the workplace. A fourth component which is also important for the safety at the workplace is the availability of systems and procedures for keeping the working environment at the workplace safe and healthy. Safe and healthy work-place environment is very important both for the workers as well as the organizational management. It does not depend on the size of the organization. It is also a productive environment since it protects the process and the equipment from getting damaged and keeps the worker away from physical injuries. It hence has a positive influence on the performance of the workers, process, and equipments. This positive influence results into a positive impact on the workers’ morale and efficiency, shop productivity, and product quality.
Safe work practices – These are guideline documents for the maintenance of safety in the organization. These practices are established in the organization for addressing significant hazards or for dealing with circumstances which can present other significant risks / liabilities for the organization. They reflect the approach of the organization for controlling safety hazards. Safe work practices are set of guidelines established to help work men to perform a task which does not require a step-by-step procedure. Safe work practices are normally written methods outlining how to perform a task with minimum risk to people, equipment, materials, environment, and processes.
Safe working load (SWL) – It is the maximum load which lifting equipment, devices, or accessories can safely handle when lifting, suspending, or lowering a mass. It is a crucial safety measure to prevent overloading and potential equipment failure during lifting operations. Safe working load is frequently used interchangeably with ‘rated load’ and includes a safety margin to account for several factors like dynamic loads and potential wear and tear.
Safe working procedures – These are guideline documents for the maintenance of safety in the organization. These procedures are established in the organization for addressing significant hazards or for dealing with circumstances which can present other significant risks / liabilities for the organization. They reflect the approach of the organization for controlling safety hazards. Safe working procedure is a step-by-step process which guides a work man through a task from start to finish in a chronological order. Safe work procedures are designed to reduce the risk by minimizing potential exposure for performing a work safely from beginning to end.
Sag – It is an increase or decrease in the section thickness of a casting caused by insufficient strength of the mould sand of the cope or of the core. In conveyor, sag is the vertical distance between the top of the load and the carrying idlers on the return side of a conveyor belt. Periodic measurements are necessary to assess sag and maintain proper belt tension.
Sagging – It is a defect characterized by a wavy line or lines appearing on those surfaces of porcelain enamel which have been fired in a vertical position. It is also a defect characterized by irreversible downward bending in a porcelain enamel article insufficiently supported during the firing cycle.
Sagging moment – It refers to the bending moment that occurs at a joint in a structure, characterized by a downward curvature, typically observed at the central joint of a beam or sub-structure under deflection.
Sagging region – It is an area within a structure, such as a beam, where downward curvature and deflection occur because of the load or other forces. The downward bending forms a concave-upward shape, where the bottom fibres of the beam experience tension and the top fibres experience compression. The term is used in several fields, including structural engineering to analyze beams and arches, and in geology to describe depressed areas of land.
Salamander – It is a heating device, normally of drum shape, in which fuel is burned in the open air by natural draft. It is also iron material which has collected in the bottom of a blast furnace during a blow.
Salamander tapping – Salamander tapping of the blast furnace is the final taping for draining out the last liquid iron from the blast furnace hearth. It is done after the blow down, especially when the blast furnace is to be completely emptied for relining during the capital repairs.
Salary – It is a form of periodic payment from an employer to an employee, which can be specified in an employment contract. It is contrasted with piece wages, where each job, hour or other unit is paid separately, rather than on a periodic basis. Salary can also be considered as the cost of hiring and keeping human resources for corporate operations, and is hence referred to as personnel expense or salary expense. In accounting, salaries are recorded in payroll accounts. A salary is a fixed amount of money or compensation paid to an employee by an employer in return for work performed. Salary is normally paid in fixed intervals, e.g., monthly payments of one-twelfth of the annual salary.
Sales agreement – It is a legally binding contract between a buyer and a seller which outlines the specific terms and conditions for the sale of goods, services, or property. It details what is being sold, the price, payment terms, delivery, and any warranties, serving as a formal record and legal protection for both parties by clarifying obligations and minimizing misunderstandings.
Sales point – It is a feature of a product which gives it a competitive advantage. This term is used in the quality function deployment methodology.
Sallen–Key filter – It consists of a family of active filters with a second-order characteristic.
Salient-pole motor – It is a synchronous electrical motor which is characterized by its rotor having distinct, protruding poles (salient poles) which project from the rotor core. These poles are typically used in low-speed synchronous motors.
Saline ground-water – It is the ground-water which has more than 4 kilograms per cubic meter of total dissolved solids.
Saline solution – It is a common term for a solution of sodium chloride (NaCl) dissolved in water (H2O).
Saline water – It is the water which has a total dissolved solids content exceeding 4 kilograms per cubic meter.
Saline water desalination – It is the process of extracting mineral components from saline water to produce freshwater, frequently utilizing methods like solar evaporation, which, despite its low efficiency because of the poor solar absorption and heat loss. The process offers a scalable solution for providing clean water.
Salt – It is an ionic compound composed of one or more anions and one or more cations.
Salt bath – It refers to either a molten salt bath which is used in industrial processes, particularly for heat treatment of materials. Industrially, it involves immersing a component in molten salt for heating and sometimes chemical reactions, like hardening or carburizing.
Salt bath carburizing – In it the baths contain cyanides, cyanates, or carbon-carbonate blends. These are particularly useful for producing thin carburized cases because the carburizing time can be precisely controlled.
Salt bath heat treatment – It is the heat treatment for metals carried out in a bath of molten salt.
Salt bath nitro-carburizing – It is a surface hardening process where both nitrogen and carbon are diffused into the surface of a ferrous material by immersing it in a molten salt bath. This process, also known as ferritic nitro-carburizing (FNC), improves wear and fatigue resistance, and sometimes corrosion resistance, while maintaining the core ductility of the steel.
Salt bath quenching – It is a heat treatment process where a heated metal component is rapidly cooled by immersing it in a molten salt bath. This process is used to harden the metal and achieve specific metallurgical properties by controlling the cooling rate. The salt bath provides a uniform and controllable heat transfer, which helps to minimize distortion and cracking during the cooling process.
Salt bridge – It is a device which is used to connect reduction with oxidation half-cells in an electro-chemical cell.
Salt fog test – It is also known as salt spray test. It is an accelerated corrosion test in which samples are exposed to a fine mist of a solution normally containing sodium chloride, but sometimes modified with other chemicals.
Salting – It is the act of introducing metals or minerals into a deposit or samples, resulting in false assays. It is done either by accident or with the intent of defrauding the public.
Salt spray test – It is also known as salt fog test. It is a standardized and popular corrosion test method, which is used to check corrosion resistance of materials and surface coatings. Normally, the materials to be tested are metallic (although stone, ceramics, and polymers can also be tested) and finished with a surface coating which is intended to provide a degree of corrosion protection to the underlying metal. Salt spray test is an accelerated corrosion test which produces a corrosive attack to coated samples in order to evaluate (mostly comparatively) the suitability of the coating for use as a protective finish. The appearance of corrosion products (rust or other oxides) is evaluated after a predetermined period of time. Test duration depends on the corrosion resistance of the coating. Normally, the more corrosion resistant the coating is, the longer is the period of testing before the appearance of corrosion or rust. The salt spray test is one of the most widespread and long-established corrosion tests.
Salt water – It is the water with high concentrations of sodium chloride or other salts.
Salvaged materials – These are building or construction materials which are retrieved on-site or off-site and reused after they have been removed from a building that is being demolished, remodeled, or deconstructed. These materials can include items like lumber, bricks, windows, doors, flooring, and appliances, and they offer a sustainable and cost-effective alternative to using entirely new materials. Use of salvaged materials reduces waste and conserves natural resources, as these materials are diverted from landfills and given a new life.
Samarium (Sm) – It is a rare earth chemical element having atomic number 62. It is a moderately hard silvery metal which slowly oxidizes in air. It is typical member of the lanthanide series. It normally has the oxidation state +3.
Sample – It is a portion of a material or product randomly selected to be representative of the whole. It consists of one or more units of a product (or a relatively small quantity of a bulk material) withdrawn from a lot or process stream and then tested or inspected to provide information about the properties, dimensions, or other quality characteristics of the lot or process stream. It is a portion of a material intended to be representative of the whole. In mining, it is a small portion of rock or a mineral deposit taken so that the metal content can be determined by assaying. In statistics, a sample is the portion of the population which is examined to make inferences about the population or a part or fraction of population, which represent it. Sample consists of a few items of the population. In principle a sample is to be such that it is a true representative of the population. Sample is a part or subset of a population, which is obtained through a recruitment or selection process, normally with the objective of understanding better the parent population. Statistics are computed on sample data to make formal statements about the population of interest. If the sample is not representative of the population, then statements made based on sample statistics is incorrect to some degree. By studying the sample, it is hoped to draw valid conclusions (inferences) about the population. A sample is normally used since the population is too large to study in its entirety. The sample is to be representative of the population. This is best achieved by random sampling. The sample is then called a random sample.
Sample and hold – It is a circuit which takes a sample of a changing analog value and holds onto it until the value can be processed by some other stage.
Sample average – It is the sum of all the observed values in a sample divided by the sample size. It is a point estimate of the population mean. It is also known as arithmetic mean.
Sample casting – It refers to a small-scale or prototype casting produced to test a new design, material, or process before full-scale production. These castings are used to evaluate the feasibility of a casting process, identify potential issues, and make adjustments to the design or process parameters.
Sample median – It is the middle value when all observed values in a sample are arranged in order of magnitude. If an even number of samples are tested, the average of the two middlemost values is used. It is a point estimate of the population median, or 50 % point.
Sample orientation – It refers to the orientation of a sample with respect to the major axes of the component from which it is taken. For cylindrical tensile and notch tensile samples, sample orientation
is normally defined in terms of the relation of the axis of the sample to the major grain flow pattern. It is namely (i) longitudinal ‘L’- axis of sample parallel to the major direction of grain flow, (ii) long transverse ‘LT’ or simply transverse ‘T’ for thin components – axis of sample perpendicular to the axis of major grain
flow, in the plane of the component, and (iii) short transverse ‘ST’ – axis of sample normal to the axis of major grain flow and to the plane of the component. For tear samples, sample orientation is normally defined in terms of the relation of the direction of applied stress to the major grain flow pattern and the plane of the component. It is namely (i) longitudinal ‘L’ – applied stress parallel to the major direction of
grain flow, in the plane of the component, (ii) long transverse ‘LT’ or simply transverse ‘T’ for thin components – applied stress perpendicular to the axis of major grain flow, in the plane of the component, and (iii) short transverse ‘ST’ – applied normal to the axis of major grain flow and to the plane of the component. For fracture toughness samples, sample orientation is defined in terms of the relationship of the direction of applied stress and also the direction of crack growth to the grain flow and to the major plane of the component. It is namely (i) ‘L-T’ – applied stress in the major direction of grain flow and crack growth across the width or major plane of the component, (ii) ‘L-S’ – applied stress in the major direction of grain flow and crack growth through or normal to the major plane of the component, (iii) ‘T-L’ – applied stress normal to the major direction of grain flow and crack growth along the direction of major grain flow, (iv) ‘T-S’ – applied stress normal to the major direction of grain flow and crack growth through or normal to the major plane of the component, (v) ‘S-L’ – applied stress normal to the major plane of the component and crack growth in the major direction of grain flow, and (vi) ‘S-T’- applied stress normal to the major plane of the component and crack growth normal to the major direction of grain flow. For majority of the fracture toughness testing programmes, samples representing only the ‘L-T’, ‘T-L’, and ‘S-L’ are used.
Sample percentage – It is the percentage of observed values between two stated values of the variable under consideration. It is a point estimate of the percentage of the population between the same two stated values. One stated value can be -infinity or + infinity.
Sample point – It is also called sampling point. It refers to a designated location along a pipeline where a representative sample of the fluid being transported can be extracted for analysis. This is crucial for determining the composition, quality, and other characteristics of the fluid being transported. Sample points are frequently used in several applications, including quality control, compliance testing, and monitoring of process parameters.
Sample preparation – It refers to the process of treating a sample to make it suitable for analysis. This involves extracting a representative portion of a larger material and preparing it for the specific analytical method used. The goal is to ensure the sample accurately reflects the characteristics of the whole material, allowing for reliable and precise analytical results.
Sample probe valve – It is a specialized valve designed to extract representative samples from a process stream (gas or liquid) for analysis. It typically includes a valve which controls the flow of the sample and a probe (quill) which is inserted into the process stream to collect the sample. The probe is frequently designed to minimize disturbance to the process flow and ensure a representative sample.
Sample size – it is the number of sampling units which are to be included in the sample.
Sample splitter – It is a device which is used to divide a large sample of material into smaller, more manageable portions, ensuring each portion is representative of the original bulk material. This process, also known as sub-sampling, is crucial for accurate material analysis, as it helps ensure that each test sample reflects the overall composition of the original material.
Sample standard deviation (s) – The square root of the sample variance. It is a point estimate of the population standard deviation, a measure of the ‘spread’ of the frequency distribution of a population. This value of ‘s’ provides a statistic which is used in computing interval estimates and several test statistics. For small sample sizes, ‘s’ underestimates the population standard deviation.
Sample thief – It is a pointed hollow tubular device which is used for sampling smaller particulate materials, such as powders. A typical sample thief consists of two tubes which are nestled together. Each tube has one or more slots aligned down the sample thief’s length. Before inserting the sample thief into the material being sampled, the slots are closed by rotating the inner tube. When the sample thief is in place, rotating the inner tube opens the slots, which fill with individual samples. The inner tube is then rotated to the closed position and the sample thief is withdrawn.
Sample variance (s2) – The sum of the squares of the differences between each observed value and the sample average divided by the sample size minus one. It is a point estimate of the population variance.
Sampling – It is the removal of a portion of a material for examination or analysis. It means selecting a fractional but representative part of a mineral deposit for analysis. It is also the process of taking a continually varying signal and turning it into a stream of numbers taken at regular intervals. Sampling in quality control is used for quality assurance. Quality assurance which relies mainly on inspection after production is called acceptance sampling.
Sampling distribution – A sampling distribution describes the probabilities associated with an estimator, when a random sample is drawn from a population. The random sample is considered as one of the several samples which might have been taken. Each has given a different value for the estimator. The distribution of these different values is called the sampling distribution of the estimator. Deriving the sampling distribution is the first step in calculating a confidence interval, or in conducting a hypothesis test. The standard deviation of the sampling distribution is a measure of the variability of the estimator, from sample to sample, and is called the standard error of the estimator. In several examples, the sampling distribution of an estimator is approximately normal. This follows from the central limit theorem. Then approximate (95 %) confidence intervals are found by simply taking the value of the estimate +/- 2. Sampling distribution is the probability distribution for a sample statistic. This distribution determines the ‘p’ values for statistical tests.
Sampling error – It is that part of the difference between a population value and an estimate thereof, derived from a random sample, which is due to the fact that only a sample of values is observed.
Sampling frame – For accepting any sampling procedure, it is necessary to have a list or a map identifying each sampling unit by a number. Such a list or map is called sampling frame.
Sampling frequency – It is the rate at which an analog value is sampled.
Sampling plan – It is a documented strategy which outlines how to select a representative sample from a larger population for research or quality control purposes. It specifies the population of interest, the sample size, the selection method (sampling technique), and the characteristics of the sample. Basically it provides a framework for gathering data from a subset of a group to make inferences about the entire group.
Sampling probe – It is a device which is used in pressure testing and so designed as to collect tracer gas from an area of the test object and feed it to the leak detector at the reduced pressure needed. It is also called a ‘sniffer’ or ‘sniffing probe’.
Sampling probe module – It measures the concentration of key components in gas and liquid streams to maintain precise process control. It is a pre-engineered system designed to extract a representative sample from a process stream (like a gas or liquid) for analysis. It typically consists of a sampling probe and a sample probe valve, which work together to improve safety, sample purity, and the timeliness of analysis.
Sampling process – It is a method of selecting a subset of individuals (a sample) from a larger group (a population) to study, with the goal of drawing conclusions about the entire population based on the sample’s characteristics. This is done since studying the entire population is frequently impractical because of time, cost, or resource constraints. The sampling process involves carefully selecting a representative sample to ensure that the findings can be generalized back to the population.
Sampling unit – The constituents of a population which are the individuals to be sampled from the population and cannot be further subdivided for the purpose of sampling at a time are called sampling units.
Sampling valve – It is a type of valve which used in process industries that allows taking a representative portion of a fluid (gases, liquids, fluidized, solids, or slurries) to test (e.g., by physical measurements, chemical analysis, or microbiological examination), typically for the purposes of identification, quality control, or regulatory assessment. It is a valve used for sampling. The sampling valve allows the operator to extract a sample of the product from the production line or reactor and safely store it for transportation to the laboratory where it is analyzed or to the archive room where it can be retrieved for further use.
Sand – It is a granular material high in SiO2, naturally or artificially produced by the disintegration or crushing of rocks or mineral deposits. In casting, the term denotes an aggregate, with an individual particle (grain) size of 0.06 millimeters to 2 millimeters in diameter, which is largely free of finer constituents, such as silt and clay, which are frequently present in natural sand deposits. The most commonly used foundry sand is silica. However, zircon, olivine, aluminum silicates, and other crushed ceramics are used for special applications.
Sand, backing – It is the sand in a mould back of the facing.
Sand, bank – It is the sand from a bank or pit.
Sand, blast – It is the sand used in an abrasive blasting machine for cleaning castings.
Sand blast – It is the sand driven by a blast of compressed air (or steam). It is used to clean castings, to cut, polish, or decorate glass or other hard substances, and also to clean building fronts, etc.
Sand blasting – It means abrasive blasting with sand.
Sand box – It refers to a container, frequently a bucket or a box filled with sand and used for extinguishing small fires, particularly those involving flammable liquids or electrical equipment. Sand is an effective extinguishing agent because it smothers the fire by cutting off its oxygen supply. It also refers to an isolated, controlled environment used for testing and experimentation, particularly in software development and security. It allows engineers to safely test new code, applications, or configurations without impacting the production environment or other critical systems. This approach minimizes risks and helps identify potential issues before deployment.
Sand casting – It is the metal castings produced in sand moulds.
Sand casting process – It is one of the most versatile of metal-forming processes. It is typically used to produce large parts such as machine-tool bases and components, structures, large housings, engine blocks, transmission cases, connecting rods, and other large components which, because of their size, cannot be cast by other processes. These castings are not normally used for the production of parts which need high production volumes. They are sometimes used to produce proto-type parts and at times they are the only method available for the creation of large parts which need a large crane capacity to remove from the mould. Although almost any metal which can be melted can be sand cast, sand castings have (as a result of the sand mould) a grainy surface with large dimensional variations. Hence, sand castings frequently need local finish machining operations in order to get the necessary surface finishes and dimensional tolerances.
Sand conditioning – It is the preparation of used moulding sand for reuse, which includes additions of bond, additives, and moisture etc.
Sand control – It consists of procedure whereby different properties of foundry sand, such as fineness, permeability, green strength, and moisture content etc., are adjusted to get castings free from blows, scabs, veins, and similar defects.
Sand control equipment – It consists of testing instruments such as moisture determinators, and permeability air-flow apparatus, etc., for determining the different physical properties of sands.
Sand, core – It is the sand used in making cores.
Sand core – It is a sand insert which is used to create complex internal features and cavities within a casting that cannot be formed by the pattern itself. These cores are made of sand and a binder, and they are placed into the mould to create the desired shape or space that the molten metal will then fill.
Sand dam – It is a small, permanent, permeable wall built across a seasonal riverbed to trap sand and rainwater during the wet season. This creates an underground reservoir or artificial aquifer behind the dam where water is stored within the sand, offering protection from evaporation and contamination while improving water quality through natural filtration. Sand dams provide communities with a sustainable, year-round water supply in arid and semi-arid regions by storing water in an enlarged natural aquifer, rather than in an open reservoir.
Sand dryer – It is the equipment for removing moisture from sand.
Sand, facing – It is the prepared sand used next to the pattern.
Sand, floor – It is the sand used in floor moulding.
Sand grain distribution – It is the variation or uniformity in particle size of a sand aggregate when properly screened by standard screen sizes.
Sand, heap – It is the sand prepared on foundry floor.
Sand hole – It is a pit in the surface of a sand casting resulting from a deposit of loose sand on the surface of the mould.
Sand holes – These are cavities of irregular shape and size whose inner surfaces plainly show the imprint of granular material.
Sand inclusions – These are cavities or surface imperfections on a casting caused by sand washing into the mould cavity.
Sand, lake – It is the sharp sand from the vicinity of lakes.
Sand mould – It is a mould is a form which contains the cavity into which molten metal is poured. It normally consists of two mould halves, separately made, and mated to form the mould cavity.
Sand, moulding – It is the sand used to make moulds.
Sand moulding (casting) – It is one of the most versatile of metal-forming processes, providing tremendous freedom of design in terms of size, shape, and product quality. Sand moulding processes are classified according to the way in which the sand is held (bonded). Sand moulding processes have been categorized as (i) resin binder processes which are organically bonded systems and which include no-bake binders, heat-cured binders (the Shell process and warm box, hot box, and oven-bake processes), and cold box binders, (ii) bonded sand moulds which are based on inorganic bonds and include such processes as green sand moulding, dry sand moulding, skin dried moulds, loam moulding, sodium silicate-carbon dioxide systems, and phosphate bonded moulds, (iii) unbonded sand moulding processes in which dry, unbonded, free-flowing sand surrounds the pattern. Lost foam processing, which uses expandable polystyrene patterns, and vacuum moulding, are examples of unbonded sand moulds. Lost foam moulds for large castings are sometimes backed up with a no-bake binder system.
Sand muller – It is an equipment for mixing sand by kneading and squeezing.
Sand mulling – It is a method of evenly distributing the bond around the sand grain by a rubbing action.
Sand, open – It is the sand through which gases can pass freely.
Sand plow – It is a bladed device used to divert sand from a belt conveyor into a sand hopper.
Sand, natural – It is the naturally bonded sand as distinguished from that which is formed synthetically.
Sand porosity – It is the volume of the pore spaces or folds in a sand. It is not synonymous with permeability).
Sand processing – It refers to the preparation, use, and sometimes recycling of sand for creating moulds used in the sand-casting process. This process involves using sand, frequently mixed with binders and additives, to form the mould cavity into which molten metal is poured to create castings.
Sand reclaimer – It is the equipment for removing extraneous material from used sand and reconditioning it for further use.
Sand reclamation – It means processing of used foundry sand by thermal, air, or hydraulic methods so that it can be used in place of new sand without substantially changing the foundry sand practice.
Sand, river – It is the sand taken from river bed.
Sand, silica – It is the sand composed of almost pure silica.
Sand slinger – It is a moulding machine which throws sand into a flask or core-box, by centrifugal action.
Sandstone – It is a sedimentary rock consisting of grains of sand cemented together.
Sand, synthetic – It is the moulding sand prepared by adding clay or other bond to the sand which is practically free of those materials.
Sand tempering – It means adding sufficient moisture to moulding sand to make it workable. It is dampening and cutting over or otherwise mixing sand to produce uniform distribution of moisture, and allowing time for migration of water molecules.
Sand toughness – It is the indication of moulding sand workability, particularly with reference to ramability, since the tougher the sand, the harder it is to ram tightly against the pattern. It is normally given as a number got by multiplying deformation by green compressive strength times 1,000.
Sand wall – It is the temporary independent wall separated from a slag pocket wall. It facilitates slag removal and protects permanent wall.
Sandwich construction – It is a panel composed of a lightweight core material, such as honeycomb, cellular or foamed plastic, and so forth, to which two relatively thin, dense, high-strength or high-stiffness faces, or skins, are adhered.
Sandwich cross-sections – These cross-sections are composite. They normally consist of a low to moderate stiffness core which is connected with two stiff exterior face sheets. The composite has a considerably higher shear stiffness to weight ratio than an equivalent beam made of only the core material or the face sheet material. The composite also has a high tensile strength to weight ratio.
Sandwich-hologram method – It is a technique in holography where multiple hologram plates are sandwiched together to compare reconstructed wave-fronts from different exposures. This allows for the independent manipulation of the reconstructed wave-fronts, enabling the study of object deformations, determining the sign of object displacements, and identifying maximal deformations,
Sandwich materials – These are composite structures consisting of a lightweight core sandwiched between two stiffer, stronger face sheets. The face sheets are normally thin and dense, providing strength and rigidity, while the core is thicker and low-density, offering high stiffness-to-weight and strength-to-weight ratios.
Sandwich panel – It is a structure which is made of three layers namely a low-density core (e.g., mineral wool), and a thin skin-layer bonded to each side. Sandwich panels are used in applications where a combination of high structural rigidity and low weight is needed. The structural functionality of a sandwich panel is similar to the classic I-beam, where two face sheets primarily resist the in-plane and lateral bending loads (similar to flanges of an I-beam), while the core material mainly resists the shear loads (similar to the web of an I-beam). The idea is to use a light / soft but thick layer for the core and strong but thin layers for face sheets. This results in increasing the overall thickness of the panel, which frequently improves the structural attributes, like bending stiffness, and maintains or even reduces the weight.
Sandwich rolling – It means rolling two or more strips of metal in a pack, sometimes to form a roll-welded composite.
Sandwich theory – It describes the behaviour of a beam, plate, or shell which consists of three layers—two face sheets and one core. The most commonly used sandwich theory is linear and is an extension of first-order beam theory. The linear sandwich theory is of importance for the design and analysis of sandwich panels, which are of use in building construction, vehicle construction, airplane construction and refrigeration engineering.
Sanitary engineering – It is also called sanitation engineering, public health engineering, or waste-water engineering. It is the application of engineering methods to improve sanitation of human communities, mainly by providing the removal and disposal of human waste, and in addition to the supply of safe potable water. Traditionally a branch of civil engineering and now a subset of building services engineering and environmental engineering.
Sanitary ware – It consists of porcelain enamel ware such as sinks, lavatories, and bathtubs etc.
Sanitization – It is the disinfection and cleaning of an area or an item. Sanitizing uses heat or chemicals to reduce the number of micro-organisms to safe levels.
Sankey diagram – It is a data visualization technique or flow diagram which emphasizes flow / movement / change from one state to another or one time to another, in which the width of the arrows is proportional to the flow rate of the depicted extensive property. It can also visualize the energy accounts, material flow accounts, and cost breakdowns. The diagram is frequently used in the visualization of material flow analysis. It emphasizes the major transfers or flows within a system. It helps to locate the most important contributions to a flow. It frequently shows conserved quantities within defined system boundaries.
SAP – It stands for ‘systems, applications and products’ in data processing. It is best known for its ERP (enterprise resource planning) software, which helps organizations manage their operations and customer relations. SAP’s software suite integrates different organizational processes, offering a centralized system for data access and sharing across different departments.
Saponification – It is the conversion of insoluble fats and fatty acids to water-soluble soaps by alkalis. The cleaning of buffing compounds from metallic surfaces can be achieved by saponification.
Saponification number – It is a number given to quenching oils which reflects the oils quantity of compounding with fatty materials, which thereby helps evaluate the condition of these oils in service. It is the milligrams of potassium hydroxide needed to saponify 1 gram of oil. Saponification is hydrolysis of an easter with potassium hydroxide to give alcohol and potassium salt of acid. Mineral oils do not react with potassium hydroxide and are not saponifiable. Vegetable and animal oils have very high saponification values. Saponification value helps to ascertain whether the oil under reference is mineral or vegetable oil or compounded oil. All the oils have their specific saponification numbers.
Saponify -It means to convert into soap. It also means to subject to, or to undergo, saponification.
Sapphire – It is a precious gemstone. It is a variety of the mineral corundum, consisting of aluminium oxide (alpha-Al2O3) with trace quantities of elements such as iron, titanium, cobalt, lead, chromium, vanadium, magnesium, boron, and silicon.
Satellite -It is a natural or artificial object which circles another, bound only by gravity.
Satellite radio – It is a radio broadcasting service using signals from an earth satellite to customer receivers.
Satin – It is a type of finish having a satin or velvety appearance, specified for plastics or composites.
Satin finish – It is a diffusely reflecting surface finish on metals, lustrous but not mirrorlike. One type is a butler finish.
Satin weave – It is a weaving pattern producing a satin appearance. It is a weaving technique which creates a smooth, lustrous fabric surface. It is characterized by a specific pattern where warp yarns (vertical threads) float over multiple weft yarns (horizontal threads) before interlacing under one weft yarn. This results in a glossy face and a dull back, giving satin its characteristic sheen and softness.
Satisfactory level – It is a degree of quality or performance which meets the minimum expectations, requirements, or standards for a given situation or task, making it good enough for its purpose. It implies something is adequate, acceptable, or sufficient, but not necessarily outstanding or excellent.
Saturated air – It is the air which contains the maximum quantity of water vapour which it can hold at its temperature and pressure.
Saturated calomel electrode (SCE) – It is a type of reference electrode which used in electro-chemistry to establish a stable reference potential. It consists of mercury in contact with mercurous chloride (calomel, Hg2Cl2) and a saturated potassium chloride (KCl) solution. The electrode is connected to the solution being measured via a porous frit, which acts as a salt bridge.
Saturated compound – It is a chemical compound (or ion) which resists addition reactions, such as hydrogenation, oxidative addition, and binding of a Lewis base. The term is used in several contexts and classes of chemical compounds. Overall, saturated compounds are less reactive than unsaturated compounds. Saturation is derived from the Latin word ‘saturare’, meaning ‘to fill’.
Saturated gun – It is a self-biased electron gun in which electron emission is limited by space charge rather than filament temperature.
Saturated liquid – It is a liquid at its boiling point for a given pressure, existing in thermodynamic equilibrium with its vapour phase. It is a liquid where any further reduction in pressure or increase in temperature causes it to begin vapourizing, while a slight increase in pressure or decrease in temperature keeps it in the liquid state.
Saturated steam – It is the steam at the temperature and pressure at which evaporation occurs. Once the boiling point is reached, the water temperature ceases to rise and stays the same until all the water is vapourized. The water goes from a liquid state to a vapour state by receiving energy in the form of latent heat of vapourization. As long as there is some liquid water left, the steam temperature is the same as the temperature of liquid water. This steam is then called saturated steam. Steam is said to be ‘saturated’ with energy at a given and constant pressure when the addition of more heat to the generation system results in more steam, but no rise in steam temperature. In this state, the steam cannot hold more heat energy in a given volume unless pressure is allowed to rise.
Saturated temperature – It is the temperature at which evaporation occurs at a particular pressure.
Saturated vapour – It is a vapour which is in dynamic equilibrium with its liquid phase at a specific temperature and pressure, meaning the rate of molecules escaping the liquid to become vapour equals the rate of molecules returning to the liquid. This state is reached when the surrounding gas or atmosphere cannot dissolve any more of the substance, or when any further attempt to increase its partial pressure causes it to condense into liquid. The pressure exerted by a saturated vapour is called its saturated vapour pressure (SVP), and this pressure increases with temperature.
Saturated water – It is the water at its boiling point.
Saturation – It normally means a state where a system can hold or absorb no more of a substance, whether it is a solute in a solution, moisture in the air, or a material’s capacity to absorb a magnetic field. It refers to a state where a solution, gas, or compound has reached its maximum capacity to hold or dissolve a substance, meaning no more of that substance can be dissolved or absorbed under the given conditions. It is also that point in the magnetization of a substance where most magnetic domains are aligned with the external field; further increase of the magnetizing force (H) gives only small increase in the magnetization (B). In the context of color, saturation refers to the intensity or purity of a colour, indicating how vivid or dull it appears. A highly saturated colour is vibrant and intense, while a desaturated colour appears muted or washed out.
Saturation magnetization – It is the maximum magnetic moment a material can achieve when subjected to a strong external magnetic field. It represents the point where further increases in the applied field no longer significantly increase the material’s magnetization. This property is particularly relevant for ferro-magnetic materials like iron, nickel, and cobalt.
Saturator – It is a device which is used to saturate a gas with the vapour of a volatile liquid. It achieves this by bubbling the gas through the liquid, allowing the gas to become saturated with the liquid’s vapour. In essence, a saturator is a tool for introducing a specific compound into a gas stream. It is frequently used in chemical processes or for creating specific gas mixtures.
Sauter mean diameter (SMD) – It is a measure of particle size which represents the diameter of a single sphere with the same volume / surface area ratio as a collection of particles. Sauter mean diameter is the diameter of a drop which has the same ratio of volume-to-surface area as the ratio of total volume-to-total surface area in a distribution of drops. Sauter mean diameter is particularly useful in fields like aerosol science and fluid dynamics, where understanding the average size of particles or droplets is crucial.
Saw cutting – It refers to the process of using a saw, a tool with a blade and sharp teeth, to cut through materials like wood, metal, or concrete. In construction, it specifically means creating controlled breaks or joints in concrete using a saw to manage cracking and achieve precision.
Saw gumming – In saw manufacture, it is the grinding away of punch marks or milling marks in the gullets (spaces between the teeth) and, in some cases, simultaneous sharpening of the teeth, in reconditioning of worn saws, restoration of the original gullet size and shape.
Sawing – It means use of a toothed blade or disk to sever parts or cut contours. It is the cutting metal into customer specified lengths, shapes, or sizes.
Saybolt FUROL viscosity (SFV) – It is a standardized tests producing measures of kinematic viscosity. FUROL is an acronym for fuel and road oil. The test is considered obsolete, but its results are quoted widely in technical literature. In this test, the time taken for 60 ml of the liquid, held at a specific temperature, to flow through a calibrated tube, is measured, using a Saybolt viscometer. The Saybolt FUROL viscosity test occurs at 50 deg C, and uses a larger calibrated tube. This provides for the testing of more viscous fluids, with the result being approximately one tenth of the universal viscosity. The test results are specified in seconds (s), more often than not referencing the test, i.e., Saybolt FUROL seconds (SFS) – seconds, Saybolt FUROL (SSF). The precise temperature at which the test is performed is frequently specified as well.
Saybolt universal viscosity (SUV) – It is a standardized test producing measures of kinematic viscosity. This test is considered obsolete to other measures of kinematic viscosity, but its results are quoted widely in technical literature. In this test, the time taken for 60 milli litres of the liquid, held at a specific temperature, to flow through a calibrated tube, is measured, using a Saybolt viscometer. The Saybolt universal viscosity test occurs at 40 deg C. The test results are specified in seconds (s), more frequently than not referencing the test i.e., Saybolt universal seconds (SUS) – seconds, Saybolt universal (SSU)- seconds, Saybolt universal viscosity (SSUV), The precise temperature at which the test is performed is frequently specified as well.
Saybolt viscometer – It is a device used to measure the viscosity of fluids, particularly petroleum products, by measuring the time it takes for a fixed volume of fluid to flow through a calibrated orifice at a specific temperature. It is a common method for determining Saybolt viscosity, a unit of viscosity used in the petroleum industry.
Saw – It is a tool, either hand-held or machine-powered, used for cutting through materials like wood, metal, or plastic. It typically features a toothed blade or disk that moves back and forth or rotates, creating a cut.
Saw blade – It is the cutting edge of a saw, typically a thin, toothed, metal blade. It is used to cut through several materials like wood, metal, and stone. The blade’s shape and tooth design vary depending on the type of saw and the material being cut.
Saw cutting – In concrete, it is the process of making controlled cuts in hardened concrete, typically with a diamond blade, to create joints or breaks. These cuts, also known as control joints, help manage and prevent random cracking because of the shrinkage or temperature changes. By creating predetermined lines of weakness, saw cutting directs cracking along those lines, minimizing damage to the concrete’s surface and structural integrity.
Saw-plate bar – It is the bar brought to final thickness by hot or cold rolling and to final width by sawing.
S-basis – It is the minimum property value specified by the appropriate recognized and approved specifications for the material.
s-block – It is the collective name for the elements in Groups 1 and 2 of the periodic table (the alkali and alkaline metals), as well as hydrogen and helium.
Scab – Scabs are irregularly shaped, flattened protrusions caused by splash, boiling, or other problems from casting, or conditioning. They occur prior to rolling. Scabs have scale and irregular surfaces beneath them. The tend to be round or oval shaped and concentrated to only certain billets. Scabs are normally ductile when bent. If material is brittle, it can be rolled in scale. In castings, scab is a blemish on a casting caused by eruption of gas from the mould face.
Scabbing – In wear, it is a loosely used term referring to the formation of bulges in the surface. In fracture mechanics, it is identical with spalling.
SCADA – It is an acronym for supervisory control and data acquisition. It is a control system architecture comprising computers, networked data communications and graphical user interfaces for high-level supervision of machines and processes. It also covers sensors and other devices, such as programmable logic controllers, which interface with process plant or machinery.
Scaffold – The term scaffold is used when there is accretion or scab formation on the blast furnace wall which causes a decrease in the cross-sectional area of the shaft of the blast furnace. Scaffold can occur relatively at the higher level of the blast furnace shaft or relatively low in the blast furnace shaft (near the top of the bosh).
Scaffolding tube – It is a ‘welded’ tube, size 50 millimeters outside diameter x 5 millimeters wall thickness used for scaffolding which has been drift tested.
Scalability – It is the property of a system to handle a growing quantity of work. One definition for software systems specifies that this can be done by adding resources to the system. In an economic context, a scalable business model implies that an organization can increase sales given increased resources.
Scalar – It is an element of a field which is used to define a vector space. In linear algebra, real numbers or normally elements of a field are called scalars and relate to vectors in an associated vector space through the operation of scalar multiplication (defined in the vector space), in which a vector can be multiplied by a scalar in the defined way to produce another vector. Normally speaking, a vector space can be defined by using any field instead of real numbers (such as complex numbers). Then scalars of that vector space are the elements of the associated field (such as complex numbers). A scalar product operation, not to be confused with scalar multiplication, can be defined on a vector space, allowing two vectors to be multiplied in the defined way to produce a scalar. A vector space equipped with a scalar product is called an inner product space.
Scalar multiplication – It is one of the basic operations defining a vector space in linear algebra (or more normally, a module in abstract algebra). In normal geometrical contexts, scalar multiplication of a real Euclidean vector by a positive real number multiplies the magnitude of the vector without changing its direction. Scalar multiplication is the multiplication of a vector by a scalar (where the product is a vector), and is to be distinguished from inner product of two vectors (where the product is a scalar).
Scalar quantities – These are sometimes simply called scalars. These are physical quantities which can be described by a single pure number (a scalar, typically a real number), accompanied by a unit of measurement, as in 10 centimeters. Examples of scalar are length, mass, charge, volume, and time. Scalars can represent the magnitude of physical quantities, such as speed is to velocity. Scalars do not represent a direction.
Scale – It is the surface oxidation, consisting of partially adherent layers of corrosion products, left on metals by heating or casting in air or in other oxidizing atmospheres. In a boiler, scale is a hard coating or layer of materials on surfaces of boiler pressure parts. Scale also refers to a method of assigning numbers to variables, allowing for the classification, ordering, and quantification of data, with the four main types being nominal, ordinal, interval, and ratio. Scale is also a device which used to measure the weight or mass of an object. It can be a traditional weighing scale with two pans or dishes, or a modern electronic scale which displays weight digitally. Weighment refers to the process of using a scale to determine the weight or mass of something. Scale also refers to a standardized set of units or markings used to quantify or compare the magnitude of a variable. Scales are fundamental to several fields like mathematics, statistics, and engineering, allowing for precise measurement and comparison. Scale is also a set of numbers, amounts, etc., used to measure or compare the level of something, e.g., to rate the performance of an employee on a scale of 1 to 5.
Scale drawing – Scale drawing is a generic term used to describe any drawing which shows items at less than (or more than) their actual size. This is normally necessary where the item is so large or small that it is not useful or convenient to draw it at its actual size. Scale drawing demonstrates the larger objects as it is not possible to draw them in the original size. So, this means that every drawing of a project facility is a type of scale drawing. For example, a location plan has a scale of 1:1,000, a site plan has a scale of 1:200, scale of a floor plan is 1:100, and so on. The larger the size of the object under construction, the higher is the tendency of the scale.
Scale formation – It refers to the deposition of hard mineral deposits, typically on surfaces in contact with water, such as pipes, boilers, or water heaters. These deposits are mainly composed of calcium carbonate, but can also include other minerals.
Scale pit – It is a surface depression formed on a forging because of the scale remaining in the dies during the forging operation. It is a pit in the ground in which scale (such as that carried off by cooling water from rolling mills) is allowed to settle out as one step in the treatment of effluent waste water.
Scaling – It is the surface oxidation, partially adherent layers of corrosion products, left on metals by heating or casting in air or in other oxidizing atmospheres. Scaling means forming a thick layer of oxidation products on metals at high temperature. Scaling is to be distinguished from rusting, which involves the formation of hydrated oxides. It is also depositing water-insoluble constituents on a metal surface, as in cooling tubes and water boilers. In mining, scaling is the act of removing loose slabs of rock from the back and walls of an underground opening, which is normally done with a hand-held scaling bar or with a boom-mounted scaling hammer.
Scaling / leveling factors – These are special cases of control factors. They are factors which can be easily adjusted to achieve a desired functional relationship between a signal factor and the output response. For example, the gearing ratio in a steering mechanism can be easily adjusted to achieve a desired relationship between the turning radius and the steering angle.
Scalping – It means removing of surface layers from an ingot, billet, or slab. It is mechanical removal of oxide and contamination from surface of a cast slab prior to hot rolling.
Scandium (Sc) – It is a silvery-white, metallic element, frequently considered a rare earth metal. It is typically found in trace quantities in several minerals. Scandium is used in a variety of applications, including high-strength aluminum alloys, high-intensity lamps, and as a catalytic agent in glass polishing.
Scandium-stabilized zirconia (ScSZ) – It is a ceramic material consisting of zirconia (ZrO2) stabilized by scandium oxide (Sc2O3). Its key feature is high ionic conductivity, which is superior to yttria-stabilized zirconia (YSZ), making it a candidate for solid-state applications such as electrolytes in solid oxide fuel cells (SOFCs) and in oxygen sensors. The improved conductivity stems from the small ionic radius of scandium, which causes less lattice distortion and fewer steric-blocking effects compared to yttria-stabilized zirconia, facilitating oxygen ion transport.
Scanning – It means to look at all parts of (something) carefully in order to detect some feature. Scanning causes a surface, object, or part of the body to be traversed by a detector or electro-magnetic beam.
Scanning acoustic microscope (SAM) – In this method, a cone-shaped volume of continuous cast product is scanned with a spiraling detector, such as a solid ultrasonic system, which automatically detects inclusions at every location in the area of the sample surface, including from surface to centre-line of the product.
Scanning acoustic microscopy – It is a non-destructive imaging technique which uses sound waves (ultrasound) to create images of microscopic objects. It is particularly useful for revealing internal flaws and defects in materials.
Scanning Auger microscopy (SAM) – It is an analytical technique which measures the lateral distribution of elements on the surface of a material by recording the intensity of their Auger electrons versus the position of the electron beam.
Scanning capacitance microscope (SCM) – It is a type of scanning probe microscopy which uses a very sensitive tip to measure changes in capacitance between the tip and a sample’s surface. This technique allows for the mapping of electrical properties like dopant concentrations and charge carrier densities within semiconductor materials.
Scanning electro-chemical microscopy (SECM) – It is a scanning probe technique which provides high-resolution topographical and electro-chemical information about a sample’s surface by moving an ultra-micro-electrode (UME) probe over it within an electrolyte solution. The technique measures in-situ electro-chemical reactions at interfaces, visualizing local electro-chemical activity and chemical species. It is to areas like corrosion and energy studies.
Scanning electron microscope – It is a type of electron microscope which uses a focused beam of electrons to scan the surface of a sample, producing high-resolution images of the sample’s surface features. Unlike light microscopes, scanning electron microscopes utilize electron beams to achieve much higher magnifications and resolving power, enabling the visualization of minute details of a material’s surface, including its morphology, composition, and crystalline structure.
Scanning electron microscopy (SEM) – It is a high-power magnifying and imaging instrument using an accelerated electron beam as an optical device and containing circuitry which causes the beam to traverse or scan an area of sample in the same manner as does an oscilloscope or TV (television) tube. It can utilize reflected or transmitted electron optics. The scanning electron microscope provides two outstanding improvements over the optical microscope. It extends the resolution limits so that picture magnifications can be increased from 1000x to 2000× up to 30,000x to 60,000×, and it improves the depth-of-field resolution more dramatically, by a factor of around 300, hence facilitating its use in fracture studies. This method clearly reveals the three-dimensional morphology and the composition of each inclusion examined. Composition is measured with electron probe micro analyzer (EPMA). Scanning electron microscopy is capable of assessing large areas and provides rich data on inclusion chemistry, morphology, and size.
Scanning induction hardening – It is a method of induction hardening where the induction coil moves (or the work-piece is moved) along the surface of a component to be hardened, creating a continuous hardened surface. This allows for the hardening of larger, more complex shapes and areas compared to single-shot hardening.
Scanning laser acoustic microscopy (SLAM) – It is a high-resolution, high-frequency (10 megahertz to 500 megahertz) ultrasonic inspection technique which produces images of features in a sample throughout its entire thickness. In operation, ultra-sound is introduced to the bottom surface of the sample by a piezo-electric transducer, and the transmitted wave is detected on the top side by a rapidly scanning laser beam.
Scanning transmission electron microscopy (STEM) – It is an advanced electron microscopy technique which combines features of both transmission electron microscopy (TEM) and scanning electron microscopy (SEM). It uses a focused electron beam to scan across a very thin sample, much like scanning electron microscopy, but collects the electrons which are transmitted through the sample, similar to transmission electron microscopy. This allows for high-resolution imaging and spectroscopic analysis of the sample’s internal structure and chemical composition.
Scanning tunneling microscopy (STM) – It is a high-resolution imaging technique which uses the principle of quantum tunneling to create images of surfaces at the atomic scale. It achieves this by scanning a sharp, conductive tip over a sample surface and measuring the tunneling current between the tip and the sample. This current, which is exponentially dependent on the tip-sample separation, provides information about the surface topography and electronic properties.
Scanty information – It refers to data which is inadequate, insufficient, or too limited to be useful for understanding, decision-making, or forming a complete picture of a subject. It signifies a scarcity of facts, with not enough being available to provide a clear or thorough explanation.
Scarfing – It means cutting surface areas of metal objects, ordinarily by using an oxy-fuel gas torch. The operation permits surface imperfections to be cut from ingots, billets, or the edges of plate that are to be beveled for butt welding.
Scarf joint – It is a form of butt joint. It is a joint made by cutting away similar angular segments on two adherends and bonding the adherends with the cut areas fitted together. .
Scarp – It is an escarpment, cliff or steep slope along the margin of a plateau, mesa or terrace.
Scatter band – It can refer to a few different things. It refers to a visual representation of data points spread around a curve, or a band of frequencies in radio or other communication technologies, or even a geological structure with alternating layers.
Scatter diagrams – These diagrams consist of graphs drawn with pairs of numerical data, with one variable on each axis, to look for relationship between them. If the variables are correlated, the points fall along a line or curve. The scatter diagram is a type of mathematical diagram using Cartesian coordinates to display values for two variables for a set of data. The data is displayed as a collection of points, each having the value of one variable determining the position on the horizontal axis (x-axis) and the value of the other variable determining the position on the vertical axis (y-axis). These diagrams are used to investigate an association between two variables. A point represents each individual or object, and an association between two variables can be studied by analyzing patterns across multiple points. A regression line is added to a graph to determine whether the association between two variables can be explained or not. Scatter diagrams enable a person to verify whether there exists a causal relationship between two variables by checking the pattern of points. In fact, it even reveals the nature of the relationship, i.e., if it is linear or non-linear, by the shape of the pattern. Scatter diagrams are especially very useful in regression and correlation analyses.
Scattered radiation – It refers to photons which have interacted with a subject through Compton or coherent interactions, resulting in the emission of photons traveling in directions different from the primary beam, which can cause fogging and loss of contrast in radiographic images. It is a type of secondary radiation which spreads out from the point of interaction.
Scattering – It is the dispersion or diffusion in different directions because of the inter-molecular or ionic collisions as applied to the effect of the residual gas in a mass spectrometer tube or an ion beam traversing the tube.
Scattering (of radiant energy) – It is the deviations in the direction of propagation of radiant energy.
Scattering parameters – It is a matrix which describes the electrical behaviour of linear electrical networks, most prominently the distributed microwave systems.
Scattering (x-ray) – It is a general term including coherent scattering and incoherent scattering.
Scavenger conveyor – It is a conveyor system which is designed for the removal of residual material or debris. Regular inspections are crucial to ensure the efficiency and reliability of scavenger conveyors.
Scavengers – These are solid additives which are added to lubricants to reduce corrosion resulting from dissolved oxygen. These are normally sulphite or bi-sulphite formulations which form sulfate (SO4)-2 after a reaction with oxygen
Scenario – It is a plausible and frequently simplified description of how the future can develop based on a coherent and internally consistent set of assumptions about key driving forces (e.g., rate of technology change, and prices etc.) and relationships is known as scenario. Scenarios are neither predictions nor forecasts and sometimes can be based on a ‘narrative storyline’. Scenarios can be derived from projections but are frequently based on additional information from other sources.
Schaeffler diagram – It is a tool used in materials science and engineering, particularly in welding and metallurgy, to predict the microstructure of welds and castings in stainless steels. It is essentially a graphical representation which helps determine the expected phases (like austenite, ferrite, and martensite) based on the chemical composition of the steel.
Scheelite – It is a tungsten ore mineral with the chemical formula CaWO4. It is a significant source of the element tungsten. It also known as wolfram.
Scheelite structure – It is a crystal structure characterized by two intercalated diamond lattices, where ‘A’ cations are coordinated by eight oxygen anions and ‘B’ cations are tetrahedrally coordinated by oxygen anions.
Scheil equation – It is a model which describes solute redistribution during the solidification of alloys. It predicts the composition of the solid and liquid phases as solidification progresses, assuming local equilibrium at the solid-liquid interface and no diffusion within the solid phase. Essentially, the Scheil equation helps understand how impurities concentrate in the liquid phase as solidification occurs.
Schematic assembly drawing – It is very difficult to understand the operating principles of complicated equipment, merely from the assembly drawings. Schematic representation of the unit facilitates easy understanding of its operating principle. It is a simplified illustration of the equipment or of a system, replacing all the elements, by their respective conventional representations.
Schematic diagram – It is a visual representation of a system or process using abstract, standardized symbols and lines to illustrate its structure and functionality. It is essentially a blueprint or outline which simplifies complex information into easily understandable diagrams. Electrical schematic diagram depicts the electrical connections and functions of a specific circuit arrangement without regard to the physical shape, size, or location of the elements. It is prepared to show the detailed design of a circuit and to assist in tracing the circuit and its functions. It can be prepared for any level of assembly and can include one or more levels. It includes (i) symbolic representation of each element in the circuit with the symbols interconnected to depict circuit paths, (ii) reference designations, (iii) values for such items as resistors, capacitors, and inductors, and (iv) standard type designations for such items as semiconductor devices, microcircuits, and electron tubes etc.
Schist – It is a foliated metamorphic rock the grains of which have a roughly parallel arrangement. It is normally developed by shearing.
Schmid’s law – It describes the relationship between applied stress and the shear stress acting on a slip system within a crystalline material. It states that slip (plastic deformation) in a crystal begins when the resolved shear stress on a slip system reaches a critical value, known as the critical resolved shear stress (CRSS). This law helps predict which slip system is going to activate first under a given stress, as the system with the highest resolved shear stress yields first.
Schmitt trigger – It is a circuit which behaves like a snap-action switch, suddenly changing state as an analog signal increases. It displays hysteresis.
Schmutzdecke – It is the biological ‘dirty layer’ of micro-organisms and organic matter which forms on the surface of a slow sand filter, acting as the primary mechanism for purifying water by biologically and mechanically removing contaminants. This layer performs both filtration and biological degradation, trapping and consuming bacteria, algae, and other particles to produce clean, potable water.
Schnadt sample – It refers to a specific configuration of a Charpy impact test specimen, particularly used in materials science and engineering. It involves a Charpy-V notch (CVN) impact sample with a hardened steel pin inserted behind the notch, replacing the material normally subjected to compression. This design is often used in older structures where vintage data can be the only information available and a correlation between different U-notch geometries and Charpy-V notch data is needed for a structural assessment.
Schoefer diagram – It is a graphical tool which is used to estimate the quantity of ferrite (specifically delta ferrite) in austenitic stainless-steel castings. It is based on the chemical composition of the alloy and can help predict the ferrite content without relying on complex phase diagrams.
Schoniger combustion – It is a method of decomposition of organic materials by combusting them in a sealed flask which contains a solution suitable for absorbing the combustion products. The flask is swept with oxygen before ignition.
Schottky barrier – It is a potential energy barrier formed at the interface between a metal and a semi-conductor, which creates a diode and is influenced by the differential work function between the two materials. This barrier results in a depletion region which is typically hundreds of nano-meters thick, affecting its efficiency in energy conversion applications.
Schottky diode – It is a diode which relies on the junction between a semi-conductor and a metal.
Schrodinger equation – It is a quantum state equation which represents the behaviour of an electron around an atom.
Science – Science is the accumulation of knowledge acquired by careful observation, by deduction of the laws which govern changes and conditions, and by testing these deductions by experiment. The scientific method is the corner-stone of science, and is the primary mechanism by which scientists make statements about the universe and phenomenon within it.
Science, engineering, and technology – These are interconnected disciplines, but they have distinct focuses. Science is the systematic study of the natural world through observation and experimentation, aiming to understand how things work. Engineering applies scientific knowledge to design, build, and maintain structures, machines, and systems. Technology encompasses the tools, processes, and systems developed by humans to solve problems and produce different products.
Scientific basis – It refers to the foundation of a concept, practice, or decision being built upon scientific principles, empirical data, and rigorous studies, rather than conjecture or tradition. It means the idea is supported by evidence, verifiable through the scientific method, and can withstand scrutiny and replication by other scientists.
Scientific method – it is the theoretical and empirical processes of discovery and demonstration considered characteristic and necessary for scientific investigation, normally involving observation, formulation of a hypothesis, experimentation to provide support for the truth or falseness of the hypothesis, and a conclusion which validates or modifies the original hypothesis. The scientific method cannot be used to prove that a hypothesis is true, but can be used to disprove a hypothesis. However, it can be used to mount substantial evidence in support of a particular hypothesis, theory, or relationship.
Scintillation – It is a burst of luminescence of short duration produced by an individual energetically excited particle as it releases energy.
Scintillation counter – It is an instrument which is used to detect and measure radioactivity by detecting gamma rays’ It is more sensitive than a Geiger counter.
Scissors – It is a hand operated cutting tool. Shear normally refers to a larger, heavier-duty version of scissors. Scissors are frequently used for tasks like cutting fabric, or metal. While both are cutting implements, scissors are typically smaller and used for more general purposes, whereas shears are designed for specific, frequently more demanding, cutting jobs.
Scissor lift conveyor – It is a conveyor which is equipped with a scissor lift mechanism for adjusting the height of the conveyor bed. Consistent checks are necessary to verify proper functioning, stability, and safety of scissor lift conveyors.
Scleroscope hardness – It is measured in Shore Scleroscope units. It, is a relative measure of a material’s resistance to localized plastic deformation, determined by the height of rebound of a diamond-tipped hammer dropped from a fixed height.
Scleroscope hardness number (HSc or HSd) – It is a number related to the height of rebound of a diamond-tipped hammer dropped on the material being tested. It is measured on a scale determined by dividing into 100 units the average rebound of the hammer from a quenched (to maximum hardness) and untempered AISI (American Iron and Steel Institute) W-5 tool steel test block.
Scleroscope hardness test – It is a dynamic indentation hardness test using a calibrated instrument which drops a diamond-tipped hammer from a fixed height onto the surface of the material being tested. The height of rebound of the hammer is a measure of the hardness of the material.
Scope – It is the defined features and functions of a product, or the scope of work needed to finish a project. Scope involves getting information needed to start a project, including the features the product needs to meet its stakeholders’ requirements.
Scoping – It is used to identify the key issues of concern at an early stage in the planning process. Scoping is carried out at an early stage in order to aid site selection and identify any possible alternatives. The scoping process involves all interested parties such as the proponent and planning or environmental agencies and members of the public. In project management, scoping is the process of determining and documenting what a project is to include or not to include, including its goals, deliverables, tasks, costs, and deadlines. It defines the boundaries of a project and ensures everyone understands the specific intentions and goals. Essentially, scoping establishes a clear understanding of the project’s parameters, which helps teams stay focused and prevents scope creep.
Scoping study – A Scoping study is an order of magnitude technical and economic study of the potential viability of Mineral resources. It includes appropriate assessments of realistically assumed Modifying factors together with any other relevant operational factors which are necessary to demonstrate at the time of reporting that progress to a Pre-Feasibility study can be reasonably justified.
Score-sheet – It is a formal scoring sheet used to objectively assess criteria in evaluations or a tool to analyze data to determine performance metrics. It can also be a digital tool for collecting, analyzing, and displaying performance statistics for several applications.
Scorch – It is premature vulcanization of a rubber compound, normally because of the excessive heat history.
Scoria – It refers to the refuse or slag left behind after a metal has been smelted from its ore. It is essentially the unwanted material which remains after the metal is extracted, frequently containing several impurities and oxides. In geology, scoria refers to a type of volcanic rock which is vesicular (containing gas bubbles or voids) and cinder-like. It is formed from rapidly cooling lava that contains a high amount of gas, resulting in a porous texture.
Scorification – It is the oxidation, in the presence of fluxes, of molten lead containing precious metals, to partly remove the lead in order to concentrate the precious metals.
Scoring – It is the formation of severe scratches in the direction of sliding. Scoring can be because of the local solid-phase welding or to abrasion. The term scuffing is sometimes used as a synonym for scoring. Minor damage is normally called scratching rather than scoring. In tribology, it is a severe form of wear characterized by the formation of extensive grooves and scratches in the direction of sliding. It is also the act of producing a scratch or narrow groove in a surface by causing a sharp instrument to move along that surface. It is the marring or scratching of any formed metal part by metal pickup on the punch or die. Scoring is also the reduction in thickness of a material along a line to weaken it intentionally along that line. It is the formation of severe scratches in the direction of sliding. It is also the act of producing a scratch or narrow groove in a surface by causing a sharp instrument to move along that surface. It is the marring or scratching of any formed metal part by metal pickup on the punch or die. It is also the reduction in thickness of a material along a line to weaken it intentionally along that line.
Scoring rule – It is a function which quantifies the performance of a probabilistic forecast or prediction against an observed outcome. It assigns a score (normally a loss or penalty) based on how well the predicted probability distribution aligns with the actual event that occurs. Basically, it is a way to evaluate how accurate a model’s predictions are when dealing with uncertainty.
Scour – It refers to the erosion of soil or sediment around structures like bridge foundations or piers, caused by the force of flowing water. This localized erosion can weaken the foundation and potentially lead to structural failure, especially during floods or high-flow events.
Scott-T transformer – It is a transformer connection for balanced inter-connection of a two-phase system and a three-phase system.
Scouring – It is a wet or dry-cleaning process involving mechanical scrubbing. It is a wet or dry mechanical finishing operation, using fine abrasive and low pressure, carried out by hand or with a cloth or wire wheel to produce satin or butler-type finishes.
Scouring abrasion – It is a process in which hard particles or protuberances are forced against and moving along a solid surface. Sometimes this term is used to refer to abrasive wear.
Scrap – It consists of products which are discarded since they are defective or otherwise unsuitable for sale. It also consists of discarded metallic material, from whatever source, which can be reclaimed through melting and refining.
Scrap bale – It is a compact block or cube of compressed waste material, such as scrap metal, paper, plastic, or cardboard, created by a hydraulic baling press. The main purpose of forming scrap bales is to reduce the volume of the material, making it considerably easier and more cost-effective to handle, store, transport, and sort at recycling centres or processing plants.
Scraper – It is a device or blade used to remove material residue from the surface of the conveyor belt, improving cleanliness and preventing carryback. It is a system for removing residues from a conveyor belt. It is also exclusion seal which has metallic or other firm lips or scraping elements. It serves to remove foreign material from a reciprocating shaft.
Scraper blade – It is a sharpened component designed to press against a surface, using friction or a cutting action to dislodge, remove, or lift materials. They come in several forms, from hand tools to parts of large machinery like earthmoving scrapers and conveyor belt cleaners. Their main function is to achieve precision by removing surface imperfections, preparing mating surfaces, or transporting bulk materials.
Scraper reclaimers – In these reclaimers, scraper blades (toothed rectangular steel plates) are attached to two parallel strands of chain at regular interval. The travel of chains along with scraper blades scrapes / drags the material from the stockpile and discharges it on the yard conveyor. In bucket reclaimers, which can be bridge type bucket wheel reclaimer, boom type bucket wheel reclaimer, or drum type reclaimer, scooping buckets scoop the material from the stockpile. The scooped material falls on the receiving / intermediate conveyor which can be bridge conveyor, boom conveyor, or barrel conveyor. The receiving conveyor in turn discharges the material on the yard conveyor. If there is a need for blending then the material is scraped / scooped from the face / front (whole cross section of the pile) of a pile. When blending is not needed, the material is scraped / scooped from the side of a pile. When material is scraped / scooped from the face of a pile, there is normally a harrow / rake attached to the reclaimer which brings the material to the bottom, from where it is taken up by scrapers or buckets. The scraper type reclaimers are lighter in weight and are cheaper as compared to boom type bucket wheel reclaimers. However, in scraper type reclaimer, more numbers of components (chain links, pins, guides and scraper blades) are subjected to material abrasion as compared to boom type bucket wheel reclaimer. In boom type bucket wheel reclaimer, only bucket edges are subjected to abrasion during reclaiming operation which can be made from wear resistant materials and can be easily maintained. Hence, boom type bucket wheel reclaimers are used for heavier duty and reliable operation.
Scrap-less nut quality wire rod – Wire rods to be drawn into wire for scrap-less nuts are produced by specially controlled production practices. They are subjected to shop floor tests and inspection designed to ensure internal soundness, freedom from harmful segregation, and harmful surface defect for satisfactory performance during cold heading, cold expanding, cold punching, and thread tapping. Wire rods for scrap-less nut wire, are normally made from low carbon resulphurized steels. Non-resulphurized steels are also used. These steels normally are furnished only in grades containing more carbon than the resulphurized grades and with phosphorus content 0.035% maximum and sulphur content 0.045 % maximum (heat analysis). It is customary to produce these steels to a specified sulphur range of either 0.08 % to 0.13 % or 0.04 % to 0.09 %. Because of the practice used in making the steel and the degree to which sulphur segregates, the sulphur content at several locations in a billet can vary from the indicated range.
Scrap metal – It is the metal meant for remelting. It includes scrapped machinery fabricated items such as rail or structural steel and rejected castings (metal to be re-melted, castings which have to be re-melted).
Scrap sorting – It is the process of separating different types of scrap materials, especially metals, based on their composition, quality, and type, to ensure proper recycling and reuse. It involves identifying and segregating several metals like ferrous and non-ferrous, as well as other materials like plastics and organic waste. This process is crucial for maximizing the efficiency and sustainability of recycling, especially in the steel industry, by ensuring the purity and quality of recycled materials.
Scrap substitute – It is the raw material which can be charged in place of scrap in electric arc furnaces and basic oxygen furnaces. Scrap substitutes include, among others, direct reduces iron, hot briquetted iron, iron carbide, and pig iron.
Scratch – It is a groove produced in a solid surface by the cutting and / or plowing action of a sharp particle or protuberance moving along that surface. For rolled products, scratch is a sharp indentation in the surface normally caused by a machine or during handling. For extrusions, scratch is a synonym for handling mark.
Scratch brush finish – It is a finish on non-ferrous metals produced by buffing which shows a combination of coarse lines with a slight underlying luster.
Scratch defect – Scratches are furrow like depressions which always run longitudinally. They vary from minute sharp almost crack like indentations to large, flat-bottomed furrows with partly projecting or overlapping edges according to the source of the defect. Scratches are detected visually and are caused by unintentional contact with build-up on mechanical parts and mill components during rolling. Scratches are because of the scoring of the stock by sharp or pointed objects. The defect typically has a more rounded bottom and less scale than a seam or crack. The defect can be detected with the naked eye or with low magnification, even in scaled condition. It seldom opens up in upsetting or torsion tests. Micro-examination can distinguish a scratch from a seam, lap, or crack. The defect can be caused by the uneven surface of guide parts on which scale or particles of the rolled product have built up. Poorly machined, worn, or broken guides can also cause scratches.
Scratch, drawn-in – It is a scratch occurring during the fabricating process and subsequently drawn over, making it relatively smooth to the touch.
Scratch, friction – It is a scratch caused by relative motion between two contacting surfaces.
Scratch, handling – It is a more severe form of rub mark.
Scratch hardness – It refers to the resistance a material shows when a sharp, harder object is dragged across its surface. This resistance is a combination of indentation and sliding. Scratch hardness is one type of hardness, alongside indentation hardness (resistance to indentation) and rebound hardness (resistance to elastic rebound). Scratch hardness is a material’s resistance to being scratched or permanently deformed by a harder object. It’s a measure of how well a material withstands friction and abrasion. A material with high scratch hardness will be more resistant to being scratched or damaged by other materials.
Scratch hardness test – It is a form of hardness test in which a sharp-pointed stylus or corner of a mineral sample is traversed along a surface so as to determine the resistance of that surface to cutting or abrasion. The Mohs hardness test is among the most widely used forms of scratch hardness tests, but is mainly applied to mineralogical samples or abrasives. Other scratch hardness tests involve using diamond cones, pyramids, and spherical tips, but such scratch hardness tests have not been established and standardized to the extent which macro-indentation and micro-indentation hardness tests have been.
Scratching – In tribology, it is the mechanical removal or displacement, or both, of material from a surface by the action of abrasive particles or protuberances sliding across the surfaces.
Scratching abrasion – A form of abrasion in which relatively low contact pressures on the abrading particles or protuberances cause only fine scratches and microscopic cutting chips to be produced.
Scratch, machine – It is an indentation which is straight, is in the rolling direction, and is caused by contact with a sharp projection on equipment.
Scratch, oscillation – It is minor indentations at an angle to the rolling direction which results from coil oscillation during unwinding or rewinding.
Scratch, oven – It is a scratch caused by moving contact of coating against a non-moving object in an oven.
Scratch-resistant coatings These are the coatings applied to glass surfaces to reduce the effects of frictive damage. Examples are tin oxide (SnO2) or titanium oxide (TiO2) coatings applied to glass containers.
Scratch, rolled-in – It is a scratch which is subsequently rolled. It then appears as a grayish white ladder (distinct transverse lines within the longitudinal indentation).
Scratch, slippage – It is also called scratch, tension. It is a short longitudinal indentation parallel to the rolling direction.
Scratch testing – Like indentation hardness test, it also measures the response of a material to plastic deformation. Also, since scratch formation is a form of controlled abrasive wear, it is reasonable to use the test as a means of ranking materials for their resistance to abrasion in service. This is, however, is to be done with some caution since the geometry of the indenter tip is substantially different from that of the asperities present on a surface. In practice, scratch testing is typically used to determine the scratch hardness of materials, characterize the mechanisms of deformation and material removal, compare the abrasive wear resistance of materials, and measure the adhesion strength of coatings. An examination of its application in these areas indicates that it is used more as a quality control technique, and also the measure obtained is more qualitative than quantitative.
Scratch trace – It is a line of etch markings produced on a surface at the site of a pre-existing scratch, the physical groove of the scratch having been removed. The scratch trace develops when the deformed material extending beneath the scratch has not been removed with the scratch groove and when the residual deformed material is attacked preferentially during etching.
Screen – It is the woven wire or fabric cloth, having square openings, used in a sieve for retaining particles larger than the particular mesh size. ISO (International Organization for Standardization) screen sizes are normally used. It is one of a set of sieves, designated by the size of the openings, used to classify granular aggregates such as sand, ore, or coke by particle size. It is also a perforated sheet placed in the gating system of a mould to separate impurities from the molten metal.
Screen analysis – It is also known as sieve analysis. It is a method to determine the particle size distribution of a granular material. It involves passing the material through a series of sieves with decreasing mesh sizes and measuring the mass retained on each. This process helps in classifying particles based on their size.
Screen aperture – It is the opening through which particles pass during the screening process, with its effective dimension varying based on the angle at which particles approach the aperture. The design of the screen and its slope can influence the likelihood of particles passing through, affecting screening efficiency.
Screen classification – It is also known as sieving or screening. It is a process which separates powders based on particle size by passing them through a specific mesh or screen. This method is normally used for materials with larger particle sizes, typically larger than 44 micrometers (325 mesh). By using multiple screens of varying mesh sizes, powders can be further categorized into different size fractions, which can be useful for different applications, such as determining particle size distribution or removing oversized particles.
Screening – It is the process of separating solids into two or more products on basis of their size. The objective of screening is size control. It is also called sieving. It refers to the separation of solid particles based on size by passing them through a screen. The smaller particles pass through the screen, while the larger ones are retained. The purpose of screening is to separate from granular substance particles which are smaller than the screen opening from those that are larger. This is not as simple as it sounds, and the difficulties compound as the opening becomes smaller. This can be done dry or wet. This process is frequently used in industries and laboratories to separate materials. In case of project management, screening is the process of evaluating and comparing project proposals to determine which ones are most promising and feasible for further development or investment. It involves assessing the potential risks and rewards, feasibility, cost, and impact of each project to identify those that align best with organizational goals.
Screening efficiency – It measures how well a screen separates materials by size, calculated as the ratio of the material which is required to pass through the screen to the material that actually passes through, or vice versa, depending on the desired product. It is a key performance indicator for screening equipment, with 100 % efficiency being an ideal which is rarely achieved in practice, as some larger particles can wrongly pass through, and some smaller particles can remain on the screen.
Screening property – It is a material property for which an absolute lower (or upper) limit can be established in the material selection process. These are frequently referred to as go / no-go limits.
Screen sand – It is a sieve or riddle with openings of definite size used to separate one gain size from another or to remove lumps from sand.
Screen test – It is also known as particle size analysis or sieve analysis. It is a method used to determine the distribution of particle sizes within a material sample. It involves passing the material through a series of sieves with progressively smaller mesh sizes, and then measuring the quantity of material retained on each sieve. It is a standard test for fineness of porcelain enamel slip or powder.
Screw – It is a threaded fastener which is used to mechanically join objects. It typically has a cylindrical shaft with helical grooves or ridges (the threads) and a head which allows it to be tightened or loosened with a tool, like a screw-driver. Screws are often used in applications where the material being fastened is relatively soft, allowing the screw to cut its own thread or where a self-tapping screw is used. Screw is also a mechanism which converts rotational motion to linear motion, and a torque (rotational force) to a linear force. It is one of the six classical simple machines. The most common form of a screw consists of a cylindrical shaft with helical grooves or ridges called threads around the outside. The screw passes through a hole in another object or medium, with threads on the inside of the hole which mesh with the screw’s threads. When the shaft of the screw is rotated relative to the stationary threads, the screw moves along its axis relative to the medium surrounding it, e.g., rotating a wood screw forces it into wood. In screw mechanisms, either the screw shaft can rotate through a threaded hole in a stationary object, or a threaded collar such as a nut can rotate around a stationary screw shaft. Geometrically, a screw can be viewed as a narrow-inclined plane wrapped around a cylinder. Like the other simple machines, a screw can amplify force, i.e., a small rotational force (torque) on the shaft can exert a large axial force on a load. The smaller is the pitch (the distance between the screw’s threads), the higher is the mechanical advantage (the ratio of output to input force). Screws are widely used in threaded fasteners to hold objects together, and in devices such as screw tops for containers, vises, screw jacks and screw presses.
Screw compressor – It is a type of positive displacement compressor that uses two intermeshing, helical rotors to compress a gas, typically air, by reducing the volume of the gas between the rotors. These rotors rotate in opposite directions, drawing in air and compressing it as the space between them shrinks. The compressed air is then discharged through an outlet.
Screw conveyor – It is also called auger conveyor. It is a mechanism which uses a rotating helical screw blade, called a ‘flighting’, normally within a tube, to move liquid or granular materials. They are used in several bulk handling industries. Screw conveyors in modern industry are frequently used horizontally or at a slight incline as an efficient way to move semi-solid materials. They normally consist of a trough or tube containing either a spiral blade coiled around a shaft, driven at one end and held at the other, or a ‘shaftless spiral’, driven at one end and free at the other. The rate of volume transfer is proportional to the rotation rate of the shaft. In industrial control applications, the device is frequently used as a variable rate feeder by varying the rotation rate of the shaft to deliver a measured rate or quantity of material into a process. Screw conveyors can be operated with the flow of material inclined upward. When space allows, this is a very economical method of elevating and conveying. As the angle of inclination increases, the capacity of a given unit rapidly decreases.
Screw dislocation – It corresponds to the axis of a spiral structure in a crystal, characterized by a distortion which joins normally parallel planes together to form a continuous helical ramp (with a pitch of one interplanar distance) winding about the dislocation.
Screw-down mechanism – It is a device used to control the gap between the rolls, allowing for precise adjustment of the material being rolled. The main function of a screw-down mechanism is to adjust the roll gap, which is the space between the rotating rolls. This gap is crucial for controlling the quantity of reduction in thickness and the final shape of the rolled material. The screw-down typically involves a gear reducer and a screw. The screw is moved by a mechanism which can be operated manually or automatically. When the screw is moved, the gear reducer converts the movement into a force that moves the rolls closer or further apart. Screw-downs are essential for maintaining consistent thickness and shape during rolling, especially in mills that produce flat products like sheet metal or wire. They are also important in roughing mills, where significant thickness reduction occurs.
Screw-driver – It is a tool, manual or powered, which is for turning screws. A typical simple screw-driver has a handle and a shaft, ending in a tip the user puts into the screw head before turning the handle.
Screw extrusion – It is a material processing method where a rotating screw conveys, heats, melts, and shapes a material by forcing it through a die. The process uses a screw inside a heated barrel to apply pressure, shear, and controlled heating to the material, which can include polymers, or catalysts. The material exits the die in a continuous profile to form different products, such as pipes.
Screwed fitting – It is also called threaded fitting. It is a non-welded pipe connector which uses male or female threads to join pipes or other fittings. These fittings feature tapered grooves designed for mechanical, non-permanent connections, allowing for easy assembly and disassembly without welding. Screwed fittings are used in low-to-medium pressure systems for applications such as plumbing and irrigation, and are limited in size and pressure rating compared to welded fittings.
Screw feeders – These feeders are suitable for material which are granular / powdery or which have small size lumps (in tens of millimeter). Screw feeders are widely used for bulk materials of low or zero cohesion such as fine and granular materials which have to be dispensed under controlled conditions at low flow rates. However, as with belt feeders, design difficulties arise when the requirement is to feed along a slotted hopper outlet. An equal pitch, constant diameter screw has a tendency to draw material from the back of the hopper. To counteract this, several arrangements are advocated for providing an increasing screw capacity in the direction of feed. The screw feeder can have different arrangements such as (i) stepped pitch, (ii) variable pitch, (iii) variable pitch and diameter, and (iv) variable shaft diameter. Pitch variation is normally limited to a range between 0.5 diameters minimum to 1.5 diameters maximum. This limits the length to diameter ratio for a screw feeder to about six, making them unsuitable for long slots
Screw press – It is a high-speed press in which the ram is activated by a large screw assembly powered by a drive mechanism. In case of briquetting, screw press consists of screw extruder and a die. There are three types of screw presses. These are (i) conical screw press, (ii) cylindrical screw press with heated dies, and (iii) cylindrical screw press without externally heated dies. In the screw press, the material (with inherent binders, lignin) to be briquetted is continuously fed into a screw with heated dies, which forces the material into a cylindrical die to the point where lignin flow occurs. The briquetting technology is based on the pressure of a special screw which pushes raw material within a chamber which becomes progressively narrower. The pressure is built up along the screw rather than in a single zone as in the piston machines. Binder is needed only in small quantity in a screw press densification. However, it can be necessary if the needed temperature (200 deg C to 250 deg C) to dissolve lignin is not achieved, or in the materials which do not have the lignin content. The screw press has low capital cost, but high maintenance cost than the piston presses because of the substantial wear on the screws, which is to be reconstructed regularly. Its specific energy demand is also higher.
Screw pumps – In these pumps, the shape of the internals is normally two screws turning against each other to pump the liquid. It is a more complicated type of rotary pump which uses two or three screws with opposing thread, e.g., one screw turns clockwise and the other counter-clockwise. The screws are mounted on parallel shafts which frequently have gears that mesh so the shafts turn together and everything stays in place. In some cases, the driven screw drives the secondary screw, without gears, frequently using the fluid to limit abrasion. The screws turn on the shafts and drive fluid through the pump. As with other forms of rotary pumps, the clearance between moving parts and the pump’s casing is minimal.
Screw take-up – It is a take-up for a conveyor system in which movement of a pulley-bearing block is accomplished by means of a screw.
Screw theory – It is the algebraic calculation of pairs of vectors, also known as dual vectors, such as angular and linear velocity, or forces and moments, which arise in the kinematics and dynamics of rigid bodies. Screw theory provides a mathematical formulation for the geometry of lines which is central to rigid body dynamics, where lines form the screw axes of spatial movement and the lines of action of forces. The pair of vectors that form the Plücker coordinates of a line define a unit screw, and general screws are got by multiplication by a pair of real numbers and addition of vectors. Screw theory is an important tool in robot mechanics, mechanical design, computational geometry and multibody dynamics.
Screw thread – It is a helical groove cut into a cylindrical shaft. It is used mainly to translate torque into linear force and to facilitate the connection of objects through threaded fasteners such as screws and bolts.
Scrim – It is a low-cost reinforcing fabric made from continuous filament yarn in an open-mesh construction. It is used in the processing of tape or other B-stage material to facilitate handling. It is also used as a carrier of adhesive, to be used in secondary bonding.
Scrubber – It is also called gas washer. It is an air pollution device which reduces the temperature of an emission. In it, a liquid (normally water) spray is used to remove pollutants from a gas stream by absorption or chemical reaction. Scrubbers collect pollutants in escaping gases.
Scrubber systems – These are a diverse group of air pollution control devices (APCD) which can be used to remove some particulates and / or gases from exhaust gas streams. Traditionally, the term ‘scrubber’ is being referred to pollution control devices which use liquid to wash unwanted pollutants from a gas stream. Recently, the term is also used to describe systems which inject a dry reagent or slurry into a dirty exhaust stream to ‘wash out’ acid pollutants. Scrubbers are one of the primary devices which control gaseous emissions, especially acid gases. Scrubbers can be either wet scrubber or dry scrubber.
Scrubbing – Scrubbing is the process by which clays, slimes, and any potential oxidization present in or on the ore are removed typically by using water. The conditioning of the ore surface is done by the scrubbing for further beneficiation. This process is primitive in nature and is widely used in lumpy iron ore processing to dislodge and remove friable and soft lateritic materials, fine materials, and limonitic clay particles adhering to the ore. Wet scrubbing is also useful in hard and porous ores, which invariably have cavity / pores filled with clayey material which need substantial removal. Crushing and grinding are preformed after the scrubbing of the ore.
Scrum – It is an agile framework for managing complex work, particularly in software development, that emphasizes collaboration, iterative development, and continuous improvement. It is not a methodology but rather a framework that teams use to self-organize and work towards a common goal. Scrum utilizes specific roles, events, and artifacts to facilitate this process, frequently within short development cycles called sprints. Scrum is one of the most popular frameworks used in Agile development, which is an iterative and incremental approach to project management and software development.
Scuffing – It is the localized damage caused by the occurrence of solid-phase welding between sliding surfaces, without local surface melting. It is also a mild degree of galling which results from the welding of asperities because of frictional heat. The welded asperities break, causing surface degradation.
Scum – It refers to a layer of unwanted or impure matter which forms on the surface, frequently as a result of boiling, fermentation, or the presence of impurities like fats, oils, and grease. It can also refer to the greenish film of algae and other vegetation on the surface of a stagnant pond.
Scum collector – It is a device used in water and wastewater treatment to remove floating solids, including fats, oils, and grease (FOG), from the surface of a liquid. These collectors work by skimming the surface of a settling tank or clarifier and collecting the scum, which is then further processed or disposed of.
Scumming – It is a defect characterized by areas of poor gloss on the surface of a porcelain enamel which can be caused by uneven heat distribution in the furnace, over-firing, or under-firing.
S-curve – In the context of project management and organization, it is a graphical representation of cumulative data plotted against time, typically taking the shape of the letter ‘S’. This curve shows the progress of a project or the growth of an organization, showing the initial slow start, a period of rapid acceleration, and finally, a flattening out as it reaches maturity or completion.
SDE analysis – This classification is carried out based on the lead time needed to procure the spare part. As per this classification scarce (S) items are those items which need a very long lead time. Difficult (D) items need moderate lead time and easily available (E) Items have very short delivery and frequently these items are available off the shelf. This classification helps in reducing the lead time and ultimately it helps in the reduction of the stock out costs in case of stock outs. This also results in streamlining the purchase and receiving systems and procedures.
S-domain – It is a Laplace transform which converts a function from the time domain to the ‘complex frequency’ s-domain, making certain mathematical operations much simpler to evaluate.
SDTV – It is the abbreviation for ‘standard definition television’. It refers to a digital television system with a resolution comparable to or slightly better than that of analog television, offering a lower resolution than HDTV (high-definition television) but better than older analog formats.
Sea coal – It is the term applied to finely ground bituminous coal which is mixed with sands for foundry uses.
Seal – It is a device or material which helps join systems, mechanisms or other materials together by preventing leakage (e.g., in a pumping system), containing pressure, or excluding contamination. The effectiveness of a seal is dependent on adhesion in the case of sealants and compression in the case of gaskets. The seals are installed in pumps in a wide range of industries including chemicals, water supply, and several other applications. A stationary seal is also referred to as a ‘packing’. In tribology, it is a device which is designed to prevent leakage between relatively moving parts. It is device designed to prevent the movement of fluid from one chamber to another, or to exclude contaminants. In conveyors, seal is a component or material which is used to close gaps and prevent material leakage in conveyor systems. Regular checks and replacements are necessary to ensure effective sealing, preventing contamination and material loss.
Sealant – It is a material which is applied to a joint in paste or liquid form that hardens or cures in place, forming a seal against gas or liquid entry.
Seal bushing – These are top and bottom bushings which provide a means of sealing the piston actuator cylinder against leakage. Synthetic rubber O-rings are used in the bushings to seal the cylinder, the actuator stem, and the actuator stem extension.
Seal coat – It is the material applied to infiltrate the pores of a thermal spray deposit.
Seal compatibility – Lubricating oils are frequently used in equipment where they come into contact with rubber or plastic seal. The strength and degree of swell of these seals can be affected by the interaction with the lubricating oil. Several tests have been devised to measure the effect of base oils on different seals and under different test conditions. The strength and degree of swell of these seals can be affected by their interaction with the oil. Several tests measure the effects of base oils on different seals and under different test conditions.
Seal, dynamic – It is a sealing element used between parts which have relative motion, e.g., stem seals, seat seal O-rings, etc.
Sealed batteries – These are valve-regulated lead–acid batteries which are designed to be maintenance-free, featuring a safety vent to control gas venting during charging and discharging. They are characterized by an immobilized electrolyte, allowing installation in any position and reducing issues compared to flooded electrolyte batteries.
Sealed bearings – These are bearings in a conveyor system equipped with protective seals to prevent contaminants from entering and ensure smooth operation. Routine inspections are necessary to assess seal integrity and maintain optimal bearing performance.
Sealed edge – It is a cut edge sealed by heat applied to the protruding carcass fibres.
Sealed multi-row tapered roller bearings – Work roll bearing arrangements in hot and cold rolling mills are to be effectively sealed against large quantity of water or roll coolant which is mixed with contaminants. The work roll bearing arrangements are normally lubricated with grease. In order to reduce costs and protect the environment, there is tendency to reduce grease consumption. Better lubrication and cleanliness at the rolling contacts can help to increase bearing life. The bearings have the same main dimensions as the unsealed bearings. High quality rolling bearing grease is used which does not escape from the bearings and is only required in small quantities. The housing seals themselves are packed with simple, cheap sealing grease. Although the integrated seals reduce the design envelope available for the rollers, leading to a lower basic load rating, the sealed bearings normally have a longer life than the unsealed bearings due to the improved cleanliness in the lubrication gap. Two-row sealed tapered roller bearings are used as axial bearings for work rolls.
Sealed source – It is a device in which a radioactive material has been contained within an outer casing. This outer casing makes an accidental release of the contents extremely unlikely. Sealed sources have an extensive range of medical, educational and industrial uses, notably in general diagnosis and cancer treatments, and in the oil and gas industries.
Sea level change – Changes in sea level, globally or locally is because of the (i) changes in the shape
of the ocean basins, (ii) changes in the total mass and distribution of water and land ice, (iii) changes in water density, and (iv) changes in ocean circulation. Sea level changes induced by changes in water density are called steric. Density changes induced by temperature changes only are called thermosteric, while density changes induced by salinity changes are called halosteric.
Sea level rise – It means an increase in the mean level of the ocean.
Sealing – It is the closing of pores in anodic coatings to render them less absorbent. It also means plugging leaks in a casting by introducing thermosetting plastics into porous areas and subsequently setting the plastic with heat.
Sealing face – It is the lapped surface of a seal which comes in close proximity to the face of the mating ring of a face seal, hence forming the primary seal. With reference to lip seals, the preferred term is seal contact surface.
Sealing issues – For decreasing the nitrogen pick-up during continuous casting, the factors normally considered are sealing of shroud from ladle to tundish, and SEN from tundish to the mould.
Sealing of anodic coatings – It is a process which, by absorption, chemical reaction, or other mechanism, increases the resistance of an anodic coating to staining and corrosion, improves the durability of colours produced in the coating, or imparts other desirable properties. It is a post anodizing treatment to close layer porosity and reduce absorbency.
Sealing valve – It is the part of the bell-less top charging system. Sealing valves play an important role during the charging of the raw materials in the blast furnace. These valves are meant for sealing the bin from the blast furnace gas leakage. These valves are mainly used for equalizing pressure and releasing gas of the blast furnace charging system. These valves are located one at top of the bin and the other at the bottom of the bin. The sealing valve consists of valve body, valve seat, a flap, and an actuating cylinder. Flap closes against the seat during closing. The surfacing alloy on the sealing surface provides it with good wear resistance. The seat has a silicone rubber ring. While the metal sealing of the valve is hard sealing, the provision of rubber ring makes it soft sealing. Once the valve is closed, it does not allow any leakage through the valve. The sealing valve is hydraulically driven. The hydraulic cylinder drives the valve flap through curved arm to control the opening of the sealing valve. It can also be operated through remote automatic control through output of signal by stroke switch. The normal position of the sealing valve is the closed position.
Seal nose – It is the part of the primary seal ring of a face seal which comes in closest proximity to the mating surface and that, together with the mating surface, forms the primary seal.
Seal ring – It is the portion of a rotary control valve assembly corresponding to the seat ring of a globe valve. Positioning of the disk or ball relative to the seal ring determines the flow area and capacity of the unit at that particular increment of rotational travel. Seal ring is also known as O-ring. It is a circular elastomeric ring which is used to prevent leakage between two mating surfaces. These rings create a barrier against fluids or gases, ensuring a tight and reliable seal. They are particularly important in valve systems for controlling flow and preventing leaks.
Seal, static – It is a sealing element used as a gasket between two non-moving parts, e.g., valve bonnet O-rings, ball valve body O-rings, and flange gaskets, etc.
Seal weld – It is a weld which is designed mainly to provide a specific degree of tightness against leakage. It is a weld which does not contribute anything to the mechanical integrity of an assembly, but is made purely to seal or prevent leakage from, for example, a threaded joint.
Seal welding – It is the welding which is done mainly to get tightness and prevent the flow of cleaning solutions and zinc into otherwise enclosed areas, to prevent flash steaming which causes localized ungalvanized areas.
Seam – On a metal surface, it is an unwelded fold or lap which appears as a crack, normally resulting from a discontinuity. It is also a surface defect on a casting related to but of lesser degree than a cold shut. It is a ridge on the surface of a casting caused by a crack in the mould face. Seams are elongated surface discontinuities which occur in materials during rolling or drawing operations. These result due to under-filled areas which are closed shut during rolling passes. The under-filled areas can result because of blowholes or cracks in the material. Also seams can result from the use of faulty, poorly lubricated or oversized dies.
Seam defect – It is an unbonded fold or lap on the surface of the metal, which appears as a crack, normally the result of a defect in working which has not bonded shut.
Seam, extrusion – It is the junction line of metal which has passed through a hollow die, separated and rejoined at the exit point. Seams are present in all extruded hollows produced from the direct extrusion process and in several cases are not visible.
Seamless – It is a hollow product which does not contain any line junctures resulting from method of manufacture.
Seamless conveyance loop It is a conveyor belt devoid of splicing, necessitating regular examinations for wear, tracking, and overall condition to sustain uninterrupted and dependable operation.
Seamless mechanical tubular product – It is available both hot and cold finished and in a wide variety of finishes and mechanical properties. It is made from carbon and alloy steels in sizes up to and including 325 millimeters outside diameter. Hot finished seamless tube is produced by rotary piercing or extrusion processes. Hence, it has surfaces similar to the surface regularly produced on hot-rolled steel and, in general, cannot be held to dimensional tolerances as close as those of tubes produced by cold finishing. It is produced in sizes as small as 40 millimeters in outside diameter. Cold finished mechanical tube can be produced by means of surface removal or by cold working. Surface removal includes turning, polishing, grinding, or machining. Cold working involves cold reducing to effect changes in cross-sectional dimensions.
Seamless pipe – It is the pipe made from a solid billet, which is heated, then rotated under extreme pressure. This rotational pressure creates an opening in the centre of the billet, which is then shaped by a mandrel to form pipe.
Seamless pipe mill – It is a rolling mill for the production of seamless pipes, which are pipes made without any welds or seams, from a solid bar of steel. Rolling mills, particularly piercing mills and fine quality mills, are key components in this process, as they deform and shape the steel bar into a hollow pipe.
Seamless rolled ring forging – It is typically performed by punching a hole in a thick, round piece of metal (creating a donut shape), and then rolling and squeezing (or in some cases, pounding) the donut into a thin ring. Ring diameters can be anywhere from a few centimeters to around 10 meters. Rings forged by the seamless ring rolling process can weigh from less than 1 kilogram to up to 150 tons. Performance-wise, there is no equal for forged, circular cross-section rings used in energy generation, mining, aerospace, off-highway equipment and other critical applications. Seamless ring configurations can be flat (like a washer), or feature higher vertical walls (around a hollow cylindrical section). Heights of rolled rings range from a few centimeters to more than 3 meters. Depending on the equipment used, wall-thickness to height ratios of rings typically range from 1:16 up to 16:1, although greater proportions have been achieved with special processing. In fact, seamless tubes up to 1200 millimeters in diameter and over 6 meter long are extruded on forging presses.
Seam weld – It is a continuous weld which is made between or upon overlapping members, in which coalescence cab start and occur on the faying surfaces, or can have proceeded from the outer surface of one member. The continuous weld can consist of a single weld bead or a series of overlapping spot welds.
Seam welding – In it, a series of spot welds is made without retracting the electrode wheels or releasing the electrode force between spots. The electrode wheels can rotate either continuously or intermittently. Weld speed, current magnitude, current waveform, cooling system, and the electrode parameters of force, shape, and diameter are all related and are to be carefully selected to optimize the process and produce the highest quality weld. Seam welding joins materials along a continuous seam. It is the joining of work-pieces made of similar or dissimilar materials along a continuous seam. It can be arc-seam welding or resistance seam welding.
Seasonal cycle length – It is the length of the characteristic recurrent pattern in seasonal time series, given in terms of number of discrete observation intervals.
Seasonal differencing – It is creating a transformed series by subtracting observations which are separated in time by one seasonal cycle.
Seasonality – It is the time series characteristic defined by a recurrent pattern of constant length in terms of discrete observation intervals.
Season cracking – It is an obsolete historical term normally applied to stress-corrosion cracking of brass. It is so called since it has been first observed, in the rainy season in India, on deep drawn 70 / 30 brass cartridge cases which had been stored in horse stables where the atmosphere contained ammonia.
Sea surface temperature (SST) – It is the temperature of the sub-surface bulk temperature in the top few meters of the ocean, measured by ships, buoys, and drifters. From ships, measurements of water samples in buckets have been mostly switched in to samples from engine intake water. Satellite measurements of skin temperature (uppermost layer; a fraction of a millimeter thick) in the infrared or the top centimeter or so in the microwave are also used, but is to be adjusted to be compatible with the bulk temperature.
Seat – The seat or seal ring provides the seating surface for the disk. A valve can have one or more seats. In the case of a globe or a swing-check valve, there is normally one seat, which forms a seal with the disc to stop the flow. In the case of a gate valve, there are two seats, one is on the up-stream side and the other is on the down-stream side. A gate valve disk has two seating surfaces which come in contact with the valve seats to form a seal for stopping the flow. In some designs, the valve body is machined to serve as the seating surface and seal rings are not used. In other designs, forged seal rings are threaded or welded to the body to provide the seating surface. For improving the wear-resistance of the seal rings, the surface is frequently hard-faced by welding and then machining the contact surface of the seal ring. A fine surface finish of the seating area is necessary for good sealing when the valve is closed. Seal rings are not normally considered pressure boundary parts since the body has sufficient wall thickness to withstand design pressure without relying upon the thickness of the seal rings.
Seat leakage – It is the quantity of fluid passing through a valve when the valve is in the fully closed position and maximum available seat load is applied with pressure differential and temperature as specified.
Seat load – It is the net contact force between the closure member and seat with stated static conditions. In practice, the selection of an actuator for a given control valve is based on how much force is needed to overcome static, stem, and dynamic unbalance with an allowance made for adequate seat load.
Seat ring – It is a part of the valve body assembly which provides a seating surface for the closure member and can provide part of the flow control orifice.
Sea-water – It is the water which makes up the oceans and seas. It is a complex mixture of 96.5 % water, 2.5 % salts, and smaller quantities of other substances, including dissolved inorganic and organic materials, particulates, and a few atmospheric gases.
Sea-water corrosion – It refers to the degradation of materials, particularly metals, when exposed to seawater, which is characterized by low corrosion rates under neutral or slightly basic pH conditions and the potential for galvanic and crevice corrosion because of its high conductivity and the presence of anaerobic bacteria.
Sea-water desalination – It is the process of getting fresh water from seawater through different treatment technologies such as multi-effect distillation, multi-stage flash distillation, reverse osmosis, electrodialysis, and pervaporation. This process frequently involves complex facilities and equipment, and it is associated with substantial energy consumption and environmental concerns.
Secant modulus – It is idealized Young’s modulus derived from a secant drawn between the origin and any point on a nonlinear stress-strain curve. On materials whose modulus changes with stress, the secant modulus is the average of the zero applied stress point and the maximum stress point being considered. It is a method for determining the modulus of elasticity, which describes how a material responds to stress. It is calculated by finding the slope of a line connecting two points on a stress-strain curve, i.e., the origin (zero stress, zero strain) and a specific point on the curve representing a certain stress level. Basically, it is a measure of the average stiffness of a material over a particular stress range.
Secant modulus of elasticity – It is the slope of a straight line (a secant line) drawn from the origin of a material’s stress-strain curve to a specific point on the curve, representing the ratio of stress to strain at that particular non-zero point. It measures the average stiffness of a material over a certain deformation range, especially useful for materials which show non0linear or inelastic behaviour, or for analyzing stiffness at large deformations.
Secant of a circle – It is a line which intersects the circle at exactly two distinct points. These points of intersection are called the intercepts of the secant on the circle. The line segment connecting the two intercepts on the circle is called a chord.
Second – It is a unit of time derived from the division of the day first into 24 hours, then to 60 minutes, and finally to 60 seconds each (24 × 60 × 60 = 86400). The current and formal definition in the International System of Units (SI) is more precise. As per it ‘the second […] is defined by taking the fixed numerical value of the caesium frequency, delta Vc, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9192631770 when expressed in the unit hertz, which is equal to per second. This current definition has been adopted in 1967 when it became feasible to define the second based on fundamental properties of nature with caesium clocks. As the speed of earth’s rotation varies and is slowing ever so slightly, a leap second is added at irregular intervals to civil time to keep clocks in sync with earth’s rotation. The definition that is based on 1/86400 of a rotation of the earth is still used by the Universal Time 1 (UT1) system.
Secondary air – It is the air for combustion supplied to the furnace to supplement the primary air. It is the portion of air which is supplied to the combustion process after the initial mixing of fuel and primary air. It is added to the combustion chamber to ensure complete fuel burning and optimize combustion efficiency.
Secondary air pollutants – These pollutants are contaminants formed in the atmosphere through chemical reactions involving primary pollutants and other atmospheric substances. Unlike primary pollutants which are directly emitted from sources like vehicles or power plants, secondary pollutants are not initially released but rather created in the atmosphere as a result of these reactions. Examples are ozone, and acid rain.
Secondary air pollution – It refers to pollutants which are not directly emitted from a source but form in the atmosphere through chemical reactions between primary pollutants and other substances, like sunlight, water vapour, or other atmospheric components.
Secondary air treatment – It refers to injecting fresh air into the exhaust stream to allow for more complete combustion of unburned or partially burned fuel. This process, also known as secondary air injection, helps to reduce pollutants like carbon mono-oxide and unburned hydro-carbons, particularly during cold starts.
Secondary alloy – It is an alloy whose major constituent is obtained from recycled scrap metal.
Secondary amine – It is an organic compound where the nitrogen atom is bonded to two carbon-containing groups (alkyl or aryl) and one hydrogen atom. Basically, it is an amine where two of the hydrogen atoms in ammonia have been replaced by organic groups.
Secondary bonding – It is the joining together, by the process of adhesive bonding, of two or more already cured composite parts, during which the only chemical or thermal reaction occurring is the curing of the adhesive itself.
Secondary circuit – It is that portion of a welding machine which conducts the secondary current between the secondary terminals of the welding transformer and the electrodes, or electrode and work-piece.
Secondary clarifiers – The purpose of these clarifiers is twofold. One is to thicken the solids after biological treatment and then settle them out. The second is to produce a clear effluent of the settled solids. Clarifiers in activated sludge systems are to be designed not only for hydraulic overflow rates, but also for solids loading rates. This is because both clarification and thickening are needed in activated sludge clarifiers. Of the process variables the most important is sludge age or mean cell residence time. Another important control parameter is the solids loading rate which is defined as the required surface for suitable sludge thickening in the bottom of the unit (compression zone). The clarifiers are either of rectangular design or of circular design.
Secondary cooling technology – in continuous casting machine, while the strand is continuously withdrawn at the casting speed, solidification of steel continues beneath the mould through the different zones of cooling having a series of water sprays. The secondary cooling system consists of these different zones, each responsible for a segment of controlled cooling of the solidifying strand as it progresses through the continuous casting machine. The sprayed medium is either water or a combination of air and water (mist spray cooling). Mist spray cooling provides several advantages consisting of uniform cooling, less water requirement, and reduced surface cracking. Product quality in a continuous casting machine is considerably influenced by temperature variations during strand cooling in secondary cooling zone. Hence secondary cooling zone has a very important function for the maintenance of a correct temperature parameter and is crucial to the quality of the cast steel product. Since the quality of steel depends on the behaviour of the surface temperature and the solidification of steel front in time, it is to a large extent defined by the intensity of the water sprays. Improper cooling conditions can have detrimental impact on stress distribution in solidified shell. First of all, overcooling can lead to the formation of cracks. Moreover, there must be a smooth transition of the surface temperature as the steel passes through in the secondary cooling zone. In addition, under cooling of the strand during secondary cooling can result in a liquid pool that is too long. These technological requirements demand more efficient and reliable spray cooling and result in constraints that must be imposed on the secondary cooling process. The spray flow rates are normally adjusted to control the strand surface temperature until the molten core is solid enough to reach the metallurgical length.
Secondary cooling zone – Secondary cooling system consists of several zones. Each zone is meant for a segment of controlled cooling of the solidifying strand as it progresses through the machine. The sprayed medium is either water or a combination of air and water. The heat transfer occurs in this region through all the three ways namely radiation, conduction, and convection. The predominant form of heat transfer in the upper regions of the secondary cooling area is by radiation. As the product passes through the rolls, heat is transferred through the shell as conduction and also through the thickness of the rolls, as a result of the associated contact. This form of heat transfer follows the Fourier law. The third form of heat transfer mechanism occurs by fast moving sprayed water droplets or mist from the spray nozzles, penetrating the steam layer next to the steel surface, which then evaporates. This convective mechanism is as per the Newton’s law of cooling. The heat transfer in the secondary zones serves the functions of (i) enhancing and controlling the rate of solidification (ii) strand temperature regulation through spray water intensity adjustment (iii) machine containment cooling. Secondary cooling zone in association with a containment section is positioned below the mould, through which the strand, the major portion of which is still in liquid state, passes and is sprayed with water or air mist for further solidification of the strand.
Secondary crack – It is a crack which is present in a component that has a larger, more obvious crack. The secondary crack can be parallel to the main crack, or it can have another orientation.
Secondary creep – It is the second stage of creep characterized by a nearly constant creep rate, resulting from a balance between plastic deformation and strain hardening. It is the creep strain occurring at a minimum and almost constant rate. It is the stage where the strain rate eventually reaches a minimum and then becomes relatively constant as a result of the balance between work hardening and annealing (thermal softening) of the material. It typically occurs for the majority of the creep life.
Secondary dendrite arm spacing (SDAS) – It is a micro-structural parameter which refers to the average distance between secondary arms of dendrites in a solidified alloy. It is a crucial factor influencing the mechanical properties of cast metals, particularly aluminum alloys. Secondary dendrite arm spacing is used to characterize the micro-structure and is related to cooling rates during solidification and the resulting material properties.
Secondary descaling – Between the crop shear and the first rolling stand of the finishing mill, there is normally second scale breaker, whose task is the final scale removal. Water sprays above and below the transfer bar at around 20 mega-pascal (MPa) pressure break up the scale which has re-formed (secondary scale), as well as any scale which has persisted through earlier descaling operations. Level adjustment of the top spraying headers and water collecting troughs enables optimum adaption of the transfer bar being handled. Due to the special nozzle arrangement, different degrees of cooling on the transfer bar upper-side underside are minimized. After secondary descaling, the bar is pinched by a pair of pneumatically-actuated rolls to mechanically loosen any remaining scale, which, as the processing temperatures cool off, becomes increasingly sticky even as it returns ever more slowly to the surfaces of the still red-hot steel.
Secondary electrical circuit – In an electric arc furnace, it is the part of the system which delivers low-voltage power to the furnace’s electrodes, allowing them to create an arc and melt scrap metal. It is essentially the pathway for electricity to flow from the transformer’s secondary windings to the electrodes, powering the melting process. The components of secondary electric circuit are (i) delta closure, (ii) power cables, (iii) bus bar / current conducting arm, (iv) electrode heads / contact pads, (v) electrode regulation, and (vi) electrodes.
Secondary electrons – These electrons are low-energy electrons which are produced when a primary electron beam interacts with a material. These electrons have been ejected from the material’s atoms because of the inelastic scattering with the primary beam. They are characterized by their low energy (typically less than 50 eV) and play a crucial role in techniques like scanning electron microscopy (SEM), where they provide information about the surface topography and composition of a sample.
Secondary emission – It is a phenomenon where primary incident particles of sufficient energy, when hitting a surface or passing through some material, induce the emission of secondary particles. The term frequently refers to the emission of electrons when charged particles like electrons or ions in a vacuum tube strike a metal surface; these are called secondary electrons. In this case, the number of secondary electrons emitted per incident particle is called secondary emission yield. If the secondary particles are ions, the effect is termed secondary ion emission. Secondary electron emission is used in photomultiplier tubes and image intensifier tubes to amplify the small number of photo-electrons produced by photoemission, making the tube more sensitive. It also occurs as an undesirable side effect in electronic vacuum tubes when electrons from the cathode strike the anode, and can cause parasitic oscillation.
Secondary enrichment – It is the enrichment of a vein or mineral deposit by minerals which have been taken into solution from one part of the vein or adjacent rocks and redeposited in another.
Secondary etching – It is the development of micro-structures deviating from primary structure through transformation and heat treatment in the solid state.
Secondary extinction – It is a decrease in the intensity of a diffracted X-ray beam caused by parallelism or near-parallelism of mosaic blocks in a mosaic crystal. The lower blocks are partially screened from the incident radiation by the upper blocks, which have reflected some of it.
Secondary fuel – It refers to a fuel which is introduced at a point downstream of the primary fuel, frequently in the combustion chamber, to further improve or modify the combustion process. It is not the main source of fuel, but rather a supplementary fuel used to optimize combustion efficiency, reduce emissions, or achieve specific combustion characteristics.
Secondary gas – In thermal spraying, it is the gas constituting the minor constituent of the arc gas fed to the gun to produce the plasma. The primary arc gas, normally argon or nitrogen, is supplemented with secondary gases such as nitrogen, helium, and / or hydrogen, in order to increase the temperature of the plasma.
Secondary hardening – It is a hardening effect which occurs on cooling certain previously hardened steel from a particular range of tempering temperature.
Secondary instruments – These instruments are measuring tools which determine a quantity’s value by comparing it to a known standard or by using a calibrated scale. In the secondary instruments, the deflection gives the magnitude of electrical quantity to be measured directly. These instruments are needed to be calibrated by comparing with another standard instrument before putting into use. In case of secondary instruments, the deflection gives the magnitude of electrical quantity to be measured directly. These instruments are needed to be calibrated by comparing with another standard instrument before putting into use. These instruments can be classified into three types namely (i) indicating instruments, (ii) recording instruments, and (iii) integrating instruments.
Secondary ion – It is an ion other than the probe ion which originates from and leaves the sample surface as a result of bombardment with a beam of primary or probe ions.
Secondary ion mass spectroscopy (SIMS) – It is an analytical technique which measures the masses of ions emitted from the surface of a material when exposed to a beam of incident ions. The incident ions are normally mono-energetic and are all of the same species, for example, 5 keV Ne+ ions.
Secondary knock-on atom – Because of energy transfer due to interaction, a sufficiently energetic particle incident on a target displaces an atom from its lattice site to an interstitial position, leaving behind a vacant lattice position. The minimum energy needed to knock off a lattice atom, called lattice displacement energy, is normally in the range of 20 eV to 100 eV in metals and its alloys. It is material-dependent. The atom which is hit by a neutron is known as primary-knock-on atom (PKA). If a primary-knock-on atom has enough kinetic energy, it can knock off another lattice atom (called secondary knock-on atom) during its movement beyond a lattice distance, and this mechanism can lead to a cascade of displacements.
Secondary manufacturing operation – It is a manufacturing operation which is used to impart close tolerances or controlled surface finish to a part. Machining operations are a good example.
Secondary manufacturing processes – These are operations performed on a work-piece after primary manufacturing to refine it, improve its properties, or add features. These processes are important for achieving the desired final product characteristics, such as improved surface finish, dimensional accuracy, or specific functionalities.
Secondary metal – It is the metal which is recovered from scrap by remelting and refining.
Secondary nucleation – It is a nucleation process which occurs because of the presence of seed crystals in a solution, influencing the formation of new nuclei based on factors such as crystal size and interaction with the solution. It includes different types such as apparent secondary nucleation, true secondary nucleation, and contact nucleation, which are characterized by different mechanisms of nucleus formation.
Secondary operation – It is a process performed on a work-piece after the initial manufacturing step to further refine it or add value. These operations can involve tasks like assembly, machining, coating, or other enhancements to improve the product’s quality, functionality, or appearance.
Secondary porosity – It refers to pore space in a rock which develops after the rock has been formed, through geological processes like dissolution, fracturing, or other changes. This contrasts with primary porosity, which is the pore space present in the original sedimentary material. Secondary porosity is crucial in hydrocarbon reservoirs as it can significantly increase the volume of pore space, impacting fluid flow and storage capacity.
Secondary product – It is a good or service produced by an industry in addition to its primary product, frequently considered a by-product, co-product, or residue.
Secondary radiation – It is radiation which originates from the interaction of primary radiation with matter. It is essentially radiation which is produced as a result of the absorption or scattering of other radiation. This can occur in several forms, including electro-magnetic waves or moving particles.
Secondary reinforcement – It is also known as distribution or thermal reinforcement and is used for durability and aesthetic reasons, by providing enough localized resistance to limit cracking and resist stresses caused by effects such as temperature changes and shrinkage.
Secondary safety devices – These are temperature sensors on pulleys, slip detectors, sprinklers etc. These are of relevance for the determination of the right class of conveyor belt for underground use.
Secondary seal – It is a device, such as bellows, piston ring, or O-ring, which allows axial movement of the primary seal of a mechanical face seal without undue leakage.
Secondary sector – It is also known as the industrial or manufacturing sector, focuses on transforming raw materials into finished or semi-finished goods. This sector takes the output from the primary sector (e.g., mining) and adds value through manufacturing, processing, and construction.
Secondary standard – It is a standard whose value is assigned by comparison with a primary standard of the same quantity. Secondary standards are used in industry as references for calibrating high-accuracy equipment and components, and for verifying the accuracy of working standards. Secondary standards are periodically checked at the institutions which maintain primary standards.
Secondary steel – It is the steel which does not meet the original customer’s specifications because of a defect in its chemistry, gauge or surface quality. Steel plant is to search to find another customer (who can accept the lower quality) to take the off-specification steel at a discount. While secondary steel does not affect the reported yield, margins suffer.
Secondary steelmaking – It is also called ladle metallurgy. It refers to the refining process of steel, typically after the initial melting or primary steelmaking stage. It involves further refining the steel’s composition, temperature, and cleanliness to achieve specific desired properties and quality requirements.
Secondary steel producer – It is an organization which manufactures steel products using electric arc furnaces (EAF) or electric induction furnaces (EIF), typically from scrap metal as the main raw material. They refine and process steel but do not typically engage in the initial ironmaking process from iron ore, which is characteristic of primary steel producers.
Secondary stresses – These are the strain-induced stresses which develop at structural discontinuities, such as junctions of major components in a pressure vessel, and are self-limiting because of the local yielding which mitigates their magnitude before substantial deformation occurs.
Secondary structure – In aircraft and aerospace applications, it is a structure which is not critical to flight safety.
Secondary treatment – It is a biological process which follows primary treatment, using micro-organisms to break down and remove dissolved and suspended organic matter, further purifying the water. It is also the treatment of boiler feed water or internal treatment of boiler-water after primary treatment.
Secondary voltage – In transformers, it is the voltage induced in the secondary winding, which is the coil that is not directly connected to the power source. It is the voltage which is stepped up or stepped down from the primary voltage (the voltage applied to the primary winding). Secondary voltage is the voltage maintained within a specific region of a power system to ensure an appropriate voltage profile, minimize reactive power flow, and improve system stability, typically coordinated automatically over a time scale of seconds to a minute.
Secondary waste-water treatment – It is the treatment which follows primary waste-water treatment. It involves the biological process of reducing suspended, colloidal, and dissolved organic matter in effluent from primary treatment systems and which normally removes 80 % to 95 % of the bio-chemical oxygen demand (BOD) and suspended matter. Secondary wastewater treatment can be accomplished by biological or chemical-physical methods. Activated sludge and trickling filters are two of the most common means of secondary treatment.
Secondary winding – In a transformer, it is the coil of wire which delivers the transformed voltage to the load. It is connected to the output side of the transformer, receiving energy from the primary winding through electromagnetic induction. The secondary winding’s number of turns and wire gauge are designed to provide the desired voltage and current for the connected load.
Secondary X-rays – These are the X-rays emitted by a sample irradiated by a primary beam.
Second law of thermodynamics – It states that when energy changes from one form to another form, or matter moves freely, entropy (disorder) in a closed system increases. In other words, heat always moves from hotter objects to colder objects unless energy is supplied to reverse the direction of heat flow, and not all heat energy can be converted into work in a cyclic process.
Second-phase particles – These are discrete particles of a different composition or structure than the main phase (or matrix) within a material. They are frequently present as precipitates or inclusions, and their presence can significantly influence the material’s properties, including strength, toughness, and grain growth.
Second phase (particle) volume fraction – It refers to the proportion of the total volume occupied by particles of a secondary phase within a material or mixture. It is basically the ratio of the volume of the second phase particles to the total volume of the material. This value is crucial in understanding how these particles affect the material’s properties.
Second phases – It refers to distinct regions within a material, often precipitates or inclusions, which are different from the primary, or ‘matrix’, phase. These secondary phases can significantly influence the material’s mechanical, optical, and electrical properties.
Sectional dimensions – It refer to the diameter or width of a tapered thin-walled structure (TWS) which varies with a specific gradient along the axial direction, contributing to improved stability and reduced peak crushing force under loading conditions.
Sectional products – These refer to the materials which have been shaped or rolled into specific, elongated profiles with a unique cross-section, like beams, channels, angles, or hollow sections. These are normally used in construction and other industries because of their strength, durability, and versatility.
Sectional properties – These are geometrical characteristics of an object’s cross-section, such as its area, centroid, and moment of inertia, which determine how it is going to behave under external loads. These properties are important in the structural analysis and design since they help engineers understand the relationship between forces and stresses on a structure, allowing for the creation of safe and effective designs for structural members like beams and columns.
Sectional shape – It refers to the cross-sectional configuration of a product, which can include different forms such as circular, square, oval, triangular, ’I’, ’H’ or ‘T’ etc., and can be engineered during the manufacturing process to improve specific physical characteristics of the product.
Sectional size – It refers to a measure of an object’s cross-sectional area or dimensions, which is important for calculating its mechanical properties and behaviour, such as its ability to withstand stress, strain, and forces. It describes the shape and size of the area exposed when an object is sliced perpendicularly to its length, e.g., the sectional size of a beam or column is critical for determining its load-bearing capacity.
Sectional view – In drawing, it is a type of view which reveals internal features of an object by showing it as if it were cut open along a plane. It is essentially a ‘slice’ through the object, revealing details not visible in standard orthographic views. This method is used to clarify internal details and reduce the use of hidden lines. Sectional view obtained by assuming that the object is completely cut by a plane is called a full section or sectional view. This sectioned view provides all the inner details, better than the not-sectioned view with dotted lines for inner details. The cutting plane is normally represented by its trace (vertical trace) in the view from the front and the direction of sight to obtain the sectional view is represented by the arrows. It is to be noted that, in order to obtain a sectional view, only one half of the object is imagined to be removed, but is not actually shown removed anywhere except in the sectional view. Further, in a sectional view, the portions of the object which have been cut by the plane are represented by section lining or hatching. The view also contains the visible parts behind the cutting plane. Sections are used primarily to replace hidden line representation, hence, as a rule, hidden lines are omitted in the sectional views.
Section drawing – The section drawing shows the structure / equipment in a sliced form. This kind of drawing helps identify the primary structure / equipment in relation to other surrounding structures / equipments in a building. Further, section drawings also provide information on the types of materials to be used in the assembly / erection of the structure / equipment. Section drawing shows a view of a structure as though it had been sliced in half or cut along another imaginary plane. This can be useful as it gives a view through the spaces and surrounding structures / equipment (typically across a vertical plane) which can reveal the relationships between the different parts of the buildings which are not apparent on plan drawings.
Section height – It refers to the external vertical dimension of a structural section, like a beam or column. It is the distance from the top to the bottom of the section, e.g., in an H-section (also known as an I-beam), it is the distance between the top and bottom flanges. For a hollow structural section (HSS), it’s the distance from the outside top edge to the outside bottom edge.
Sectioning – It is the removal of a conveniently sized, representative sample from a larger sample for metallographic inspection. Sectioning methods include shearing, sawing (using hacksaws, band saws, and diamond wire saws), abrasive cutting, and electrical discharge machining.
Section mill– It is a type of rolling mill which is specifically designed to produce structural sections like angles, channels, beams, and rails. The rolling process involves passing heated metal billets / blooms between grooved rolls with to create the desired cross-sectional shape.
Section modulus – It is a geometric property of a given cross-section used in the design of beams or flexural members. It is a parameter which measures a cross-section’s strength in bending, calculated as the moment of inertia (I) divided by half the cross-sectional height or thickness. For diffevarious shapes, specific formulas apply, such as S x = I x (H/2) for symmetrical sections and S x = I x / R for circular shapes.
Section number – It is the number assigned to an extruded or drawn profile (shape) for identification and cataloging purposes, normally the same number assigned for the same purpose to the die from which the profile (shape) is made.
Sectors – These are divisions within an economy or market, useful for analyzing performance or comparing organizations with similar outputs and characteristics. Economies tend to be split into different sectors, e.g., mining manufacture, service, and education etc.
Sector-specific technology – It refers to the development and application of technology solutions tailored to the unique needs and challenges of a specific industry or sector. This means that technology is not just a generic tool, but is adapted and customized to work best within a particular context, like marketing, finance, or manufacturing.
Sector-specific technology limit – It defines the scope of technology within a particular industry or economic sector, setting boundaries for its development and application. This approach ensures that technologies are tailored to the unique needs and challenges of the specific sector, rather than being a general, one-size-fits-all solution.
Sediment – It consists of eroded soil, rock and plant debris, transported and deposited by water. It is also (i) a matter in water which can be removed from suspension by gravity or mechanical means, or (ii) a non-combustible solid matter which settles out at bottom of a liquid e.g., a small percentage is present in residual fuel oils.
Sedimentary ores – These are (i) bedded ores, (ii) siderite ores, (iii) placer ores, or (iv) bog iron ores. ‘Bedded iron ores’ are often composed of oolites of hematite, siderite, iron silicate or, less commonly, limonite in a matrix of siderite, calcite or silicate. These ores have a wide geographic distribution associated with other sedimentary rocks and frequently have a fairly high phosphorus content. The ores may be self-fluxing.
Sedimentary rocks – These are secondary rocks formed from material derived from other rocks and laid down under water. Examples are limestone, shale and sandstone.
Sedimentation – It is the process of material settling out of water. It is the process of allowing suspended particles and solids to settle out of water under the influence of gravity, forming a sediment layer at the bottom of a tank or basin.
Sedimentation tank – It is also known as a settling tank or clarifier. It is a large container used in water and wastewater treatment to remove suspended solids from liquids. It works by allowing heavier particles to settle to the bottom of the tank under the force of gravity, where they are then removed.
Seebeck coefficient – It is the ratio of the generated Seebeck voltage to the temperature difference across a thermoelectric material, which can be measured using methods such as micro-machining and self-heating techniques.
Seebeck effect – It is a thermo-electric phenomenon where a temperature difference between two dissimilar electrical conductors or semi-conductors creates a voltage. Basically, when a temperature gradient exists across a material, it can produce a voltage difference. This effect is reversible, meaning that if a person applies a voltage, it creates a temperature difference. It is the principle behind thermo-couples, which are used to measure temperature.
Seed crystals – These are defined as high-quality single crystals used to initiate crystal growth and prevent multi-nucleation by providing a new growth interface. They are typically of the same composition as the desired crystal and play a crucial role in producing larger crystals with specific crystallographic orientations.
Seeding – It refers to the process of introducing small, pre-formed crystals (seeds) into a molten or solution of the same material to promote and control the formation of larger, more uniform crystals. This technique is crucial for achieving desired microstructures and properties in metal alloys.
Seemann composites resin infusion moulding process (SCRIMP) – It is a vacuum-assisted resin transfer molding process that uses a vacuum to draw liquid resin into a dry fibre preform. This method is used to create high-quality, repeatable composite parts with minimal volatile organic compound (VOC) emissions. It is a variant of vacuum-assisted resin transfer moulding (VARTM) where a highly permeable distribution medium is used to facilitate resin flow and reduce filling time.
Seepage – It the flow or movement of water through a dam, its foundation, or abutments.
Segment – In sampling, it is a specifically demarked portion of a lot, either actual or hypothetical. In a circle, segment is a plane region bounded by a circular arc (of less than ‘pi’ radians by convention) and the circular chord connecting its endpoints.
Segmentation – It is a step in digital image processing that groups picture elements of an image which notionally represent some physically significant property of the imaged objects.
Segmentation methods – These refer to techniques used to partition data into segments which represent distinct objects, frequently using supervised machine learning to train deep networks with manually segmented images or point clouds. These methods typically utilize an encoder-decoder architecture to extract features and generate segmentation masks.
Segmentation techniques – They refer to methods used to analyze and track productivity by evaluating an object’s pixel values based on colour thresholds, enabling the detection of specific elements in images or video sequences, such as background subtraction for static scenes or feature extraction from time-lapse videos.
Segment die – It is a die made of parts which can be separated for ready removal of the work-piece. It is synonymous with split die.
Segregation – It is the tendency of refuse of varying compositions to deposit selectively in difference parts of the unit. It is non-uniform distribution of alloying elements, impurities, or microphases in metals and alloys. It is also a casting defect involving a concentration of alloying elements at specific regions, normally as a result of the primary crystallization of one phase with the subsequent concentration of other elements in the remaining liquid. Micro-segregation refers to normal segregation on a microscopic scale in which material richer in an alloying element freezes in successive layers on the dendrites (coring) and in constituent network. Macro-segregation refers to gross differences in concentration (for example, from one area of a casting to another). In refractories, segregation is the separation of aggregate and fines during fabrication of a refractory to leave a honeycomb appearance and / or a layer of excess fines.
Segregation banding – It is inhomogeneous distribution of alloying elements aligned in filaments or plates parallel to the direction of working.
Segregation (coring) etching – It is the development of segregation (coring) mainly in macro-structures and micro-structures of castings.
Segregation factor – It is a measure of how unevenly elements are distributed within a solid material during solidification. It is essentially the ratio of an element’s concentration in the first part of the alloy to solidify against its concentration in the last part to solidify. A segregation factor higher than 1 indicates the element segregates toward the end of solidification, while a factor less than 1 suggests it segregates into the beginning.
Seiketsu (Standardize) – It means that employees are to discuss together and decide on standards for keeping the work place / equipments / pathways neat and clean. These standards are implemented for the whole organization and are tested / inspected randomly.
Seiri (Sort) – This means sorting and organizing the items as critical, important, frequently used, useless, or items which are not needed as of now. Items not wanted can be salvaged. Critical items are to be kept for use nearby the equipment, and items which are not to be used in near future are to be stored in some place. For this step, the worth of the item is to be decided based on utility (frequency of use) and not the cost. As a result of this step, the search time of the item at the time of need is reduced.
Seismic analysis – It is a subset of structural analysis and is the calculation of the response of a building (or non-building) structure to earth-quakes. It is part of the process of structural design, earth quake engineering or structural assessment and retrofit in regions where earth-quakes are prevalent.
Seismicity – It is the occurrence of earthquakes and tremors, which can be either natural or induced by human activities that alter stress and strains on the earth’s crust.
Seismic load – It refers to the forces exerted on a structure because of the ground movement during an earthquake. These forces are dynamic, meaning they vary in magnitude and direction over time. Understanding and incorporating seismic loads is crucial in designing structures which can withstand earthquake-induced shaking and remain safe.
Seismic prospecting – It is a geophysical method of prospecting, utilizing knowledge of the speed of reflected sound waves in rock.
Seismic surveys – These surveys are based on variations of sound velocity experienced in different geological strata. The time is measured for sound to travel from a source on surface, through the underlying layers, and up again to one or more detectors placed at some distance on surface. The source of sound can be the blow of a sledge-hammer, a heavy fallen weight, a mechanical vibrator or an explosive charge. Seismic survey determines the quality of bed-rock and can locate the contact surface of geological layers, or of a compact mineral deposit in the ground.
Seiso (Sweep) – This means cleanliness of the work-place and involves cleaning the work-place free of burrs, grease, oil, waste, and scrap etc. No loosely hanging wires or oil leakage from the equipments are to be there.
Seiton (Organize) – The concept here is that ‘each of the items has a place, and only one place’. The items are to be placed back after usage at the same place. For easy identification of the items, name plates and coloured tags are to be used. Vertical racks can be used for this purpose, and heavy items occupy the bottom position in the racks.
Seize – It means prevention of a part from being ejected from a die as a result of galling.
Seizing – It is the stopping of a moving part by a mating surface as a result of excessive friction.
Seizure – It is the stopping of relative motion as the result of interfacial friction. Seizure can be accompanied by gross surface welding. The term is sometimes used to denote scuffing.
Sejournet process – It is also called Ugine-Sejournet process. It is a direct extrusion process for metals which uses molten glass to insulate the hot billet and to act as a lubricant.
Select control method – In order to control the operating parameters, the proper control method is important to control the process effectively. On / off is one control method and the other is continuous control. Continuous control involves proportional (P), integral (I), and derivative (D) methods or some combination of these three.
Select control system – Choosing between a local or distributed control systems which fits well with respect to the process effects both the cost and efficacy of the overall control.
Selected-area diffraction (SAD) – It is the electron diffraction from a portion of a sample selected by inserting an aperture into the magnification portion of the lens system of a transmission electron microscope. Areas as small as 0.5 meters in diameter can be examined in this way.
Selected-area diffraction pattern (SADP) – It is an electron diffraction pattern got from a restricted area of a sample. The sharp spots in the pattern correspond closely to points in the reciprocal lattice of the material being studied. Normally such patterns are taken from a single crystal or a small number of crystals.
Selected item drawing – It defines refined acceptance criteria for an existing item under the control of another design activity which requires further selection, restriction, or testing for such characteristics as fit, tolerance, material (in cases where alternate materials are used in the existing item), performance, reliability, etc., within the originally prescribed limits. This drawing establishes new item identification for the selected item. A selected item drawing is prepared when it is feasible to select from an existing group of existing items those items which (i) meet the required characteristics for a particular application, and (ii) pass additional tests or inspections imposed by the using design activity for characteristics not normally specified for the original item. The selected item drawing establishes the detailed criteria on which selection of the item is based.
Selection bias – It is the bias in one’s regression estimates brought about either by an unmeasured characteristic of cases which causes only certain kinds of cases to be assigned certain treatments (self-selection bias) or by an unmeasured characteristic which causes only certain kinds of cases to be present in one’s sample (sample-selection bias).
Selective and override control – Some processes have more controlled variables than manipulated variables. Such a situation does not allow an exact pairing of controlled and manipulated variables. A common solution is to use a device called a selector which chooses the appropriate process variable from among a number of valid measurements. The purpose of the selector is to improve control system performance as well as to protect equipment from unsafe operating conditions by choosing appropriate controlled variables for a specific process operating condition. Selectors can be based on multiple measurement points, multiple final control elements, or multiple controllers.
Selection methodology – It is the process of choosing a suitable design methodology and tool set based on a comprehensive evaluation of project requirements, complexity, team capabilities, and specific application needs. It emphasizes the importance of alignment between methodology and tools for ensuring effective implementation.
Selective catalytic reduction (SCR) – It is a process for reducing nitrogen oxides (NOx) in flue gas by injecting ammonia or urea over a catalyst, resulting in the conversion of nitrogen oxides to nitrogen and water, achieving removal efficiencies of 90 % to 95 %.
Selective crushing of coals – Coal is a heterogeneous material. Its various components have a different hardness, so that during breakage by mechanical means whether the inevitable breakage in mining or crushing during coal preparation for coking, the weaker components tend to concentrate in the fine fractions and the others in the coarse fractions. These various fractions are expected to have different coking properties. This triggers the concept of selective crushing which aims at controlling the degree of crushing of different constituents of the coal blend. This technology is helpful when coals are petrographically heterogeneous. This technology is a theoretically sound technology and aims at controlling the degree of crushing of the different constituents of coal. It aims to improve homogeneity of reactive and inert components in coal. The reactive components of coals are primarily vitrinites and are the softest constituents while the mineral matters of coals are the hardest components. In conventional coal crushing units, where the entire coal is crushed together, the vitrinites get crushed to a relatively finer size compared to mineral matter constituents. For producing coke of higher quality, it is desirable to crush the mineral matter finer than the vitrinite component of the coal so that during the process of coking, when the coal charge softens, the mineral matter is assimilated better, leading to the improved strength. This is normally carried out by crushing of each coal type separately.
Selective etching – It is the process of etching a specific material at a considerably higher rate than others in a multi-material environment, facilitated by the choice of plasma chemistry and ion energy. It is normally applied in fabricating devices like metal-oxide-semiconductor transistors, where precise material removal is crucial.
Selective flotation – It is a modified flotation process used to separate one desired component from a mixture containing multiple components by using specific chemical agents to alter the surface properties of the target particle, making it more or less hydrophobic (water-repellent), and then using air bubbles to selectively attach to and lift only that component in a suspension medium. This allows for the separation of minerals from ore, or specific plastics from a mixture, by making the desired material float while the other materials remain submerged.
Selective granulation process – It is used to allow the sintering of iron ores with high alumina content, which are otherwise difficult to sinter because of the low reactivity of alumina-bearing materials and the high viscosity of primary melts. Selective granulation consists of screening the ore and sending the larger size fraction which has lower alumina content to the conventional granulation circuit, while the smaller size fraction with higher alumina content is pelletized into 2 milli-meters to 5 milli-meters granules which are incorporated in the conventional granulation circuit. The smaller size fraction contains clayish ores which are high in alumina and need higher melting temperatures.
Selective heating – It consists of intentionally heating only certain portions of a work-piece.
Selective laser melting – It is a powder bed fusion additive manufacturing process which utilizes a high-energy laser to selectively melt layers of metal powder, creating solid objects through sequential layer deposition and solidification. This process involves a protective inert gas to prevent oxidation and allows for the recycling of unfused powder for future builds.
Selective laser sintering (SLS) – It is a 3D printing process where a high-power laser selectively fuses powdered materials, typically polymers, layer by layer, creating a solid object. It’s a type of powder bed fusion (PBF) technology.
Selective leaching – It is the corrosion in which one element is preferentially removed from an alloy, leaving a residue (frequently porous) of the elements which are more resistant to the particular environment. It is also called dealloying or parting.
Selective non-catalytic reduction (SNCR) – It is a method for reducing NOx (oxides of nitrogen) emissions through the injection of a NOx-reducing agent, such as ammonia or urea, into exhaust gases at temperatures between 760 deg C to 870 deg C, resulting in the conversion of NOx into water and atmospheric nitrogen without the use of a catalyst.
Selective permeability – It is the property of membranes which allows certain molecules to pass through while retaining others, enabling processes such as gas-gas or gas-liquid separation.
Selective plating – It is also known as brush plating. It differs from traditional tank or bath plating in that the work-piece is not immersed in a plating solution (electrolyte). Instead, the electrolyte is brought to the part and applied by a hand-held anode or stylus, which incorporates an absorbent wrapping for applying the solution to the work-piece (cathode). A direct current power pack drives the electro-chemical reaction, depositing the desired metal on the substrate. In practice, movement between the anode and cathode is needed for optimum results when plating, stripping, activating, and so on.
Selective quenching – It consists of quenching only certain portions of an object.
Selective transfer – It is a process involving the transfer and attachment of a specific species from one surface to the mating surface during sliding. This term is to be distinguished from the general tribological term transfer, which involves the same general process, but which, when used by itself, does not discriminate as to which of the species present in a multi-constituent surface is transferred during sliding.
Selective waste gas recirculation system – During the sintering process the sucked air volume is normally higher than required for complete combustion of the fuel in order to allow a high velocity of the flame front. Sinter waste gas hence typically contains around 12 % to 15 % residual oxygen. It is also at a temperature which is well above the critical dew point. This is sufficient for recirculation to the sintering process after the addition of a small amount of supplementary air. In the ‘selective waste gas recirculation system’, the off-gas from selected zones of the sinter machine is mixed with cooler off-air and is then recirculated to the sinter strand. The selective waste-gas recirculation system was developed initially to keep the off-gas volume at a constant level while increasing the sintering capacity and decreasing specific emissions. This allows investment and operating costs for gas-cleaning facilities to be held at acceptable levels.
Selectivity – It is the ability of a method or instrument to respond to a desired substance or constituent and not to others.
Select measurement methods – Selecting the proper type of measurement device specific to the process ensures that the most accurate, stable, and cost-effective method is chosen. There are several different signal types which can detect different things. These signal types include (i) electric, (ii) light, (iii) pneumatic, (iv) radio waves, (v) infrared (IR), and (vi) nuclear.
Selector valve – It is also called stream selector valve. It is a type of valve which directs the flow of a fluid or gas from a single supply to one of multiple outlets, essentially allowing an operator to choose which ‘stream’ or path the fluid is to take. These valves are crucial in different applications like fire suppression systems, where they direct fire-fighting agents to specific hazard areas, or in analytical equipment, where they select different sample streams for analysis.
Selenium (Se) – It is a chemical element having atomic number 34. It has several physical appearances, including a brick-red powder, a vitreous black solid, and a grey metallic-looking form. It seldom occurs in this elemental state or as pure ore compounds in earth’s crust. Selenium is found in metal sulphide ores, where it substitutes for sulphur. Commercially, selenium is produced as a byproduct in the refining of these ores. Minerals which are pure selenide or selenate compounds are rare. The chief commercial uses for selenium today are glassmaking and pigments. Selenium is a semiconductor and is used in photocells. Applications in electronics, once important, have been mostly replaced with silicon semi-conductor devices. Selenium is still used in a few types of direct current power surge protectors and one type of fluorescent quantum dot.
Selenium rectifiers – These rectifiers consist of one type of metal rectifier, though selenium is considered a ‘metalloid’. Earlier these have been much used but now replaced by silicon semi-conductors.
Self-absorption – In optical emission spectroscopy, it is the reabsorption of a photon by the same species which emitted it, e.g., light emitted by sodium atoms in the centre of a flame can be reabsorbed by different sodium atoms near the outer portions of the flame.
Self-acting bearing – It is a journal or thrust bearing lubricated with gas.
Self-aligning bearing – It is a rolling-element bearing with one spherical raceway which automatically provides compensation for shaft or housing deflection or misalignment.
Self-aligning conveyor – It is a conveyor system which is designed to automatically adjust and maintain proper alignment. Consistent maintenance is crucial to ensure the ongoing effectiveness of self-aligning conveyors, preventing misalignment issues.
Self-aligning idler – It is an idler roller designed to automatically adjust and maintain proper alignment of the conveyor belt. Periodic checks are crucial to ensure the effective self-aligning capability and prevent issues like misalignment and uneven wear.
Self-aligning roller – It is a roller designed to automatically align and centrs the conveyor belt, preventing misalignment issues. Ongoing checks become imperative to verify the proper functioning and alignment of self-aligning rollers.
Self-aspirating burner – It is a type of burner, frequently used in heating systems, which uses the pressure of the incoming gas to draw in air for combustion without the need for a separate fan or blower. This self-induced air intake is achieved through a venturi-like design in the burner, which creates a low-pressure area that draws in air.
Self-cleaning covers – A hydrophobic property of the rubber compound makes cleaning by scrapers easier. Useful for very fine, sticky material. A disadvantage is the lower resistance to material impact and gouging.
Self-cleaning return idlers – An important consideration with return idler applications is the adherence of materials to the carrying surface of the belt. Such material can be abrasive and wear the shell of the return idler rolls. Or, this build-up can be sticky and adhere to the return idler rolls. A large build-up can cause misalignment of the return run of the belt. Several types of return idler rolls are available to overcome these difficulties. When sticky materials are a problem, rubber or urethane disc, or rubber coated helically shaped, self-cleaning return idlers can be used. Disc and helical rolls present very narrow surfaces for adhesion and thus reduce the tendency for material build up. This type of return idler sometimes is erroneously called a ‘belt cleaning idler’. Even though such idlers do ‘track-off’ material adhering to the belt surface on the return run, they do not constitute belt cleaning devices.
Self-cleaning tail pulley – It is a tail pulley which is designed to shed material buildup and prevent carryback. Regular inspections are necessary to ensure the self-cleaning functionality and proper operation of tail pulleys.
Self-consolidating concrete (SCC) – It is also called self-compacting concrete. It is a type of concrete which flows and spreads into place without needing mechanical vibration. This property makes it suitable for complex structures or areas with dense reinforcement. Self-consolidating concrete achieves compaction and consolidation through its inherent flow properties, eliminating the need for external vibration.
Self-contained breathing apparatus (SCBA) – It is also known as self-contained respirators (breathing apparatus). It is a respiratory device which provides breathable air from a portable source, allowing users to enter and work in environments which are otherwise immediately dangerous to life or health, such as those with oxygen deficiency, smoke, or toxic gases. It essentially consists of a high pressure cylinder of air or oxygen connected to a face piece through a tube with demand valve and regulator and a harness assembly for mounting the apparatus on the body.
Self-contained instrument – It is that instrument which has all the physical elements in one assembly. Examples are an analog ammeter, or mercury in the glass thermometer etc.
Self-diffusion – It is the thermally activated movement of an atom to a new site in a crystal of its own species, as, for example, a copper atom within a crystal of copper.
Self-discipline – It is the control of one’s impulses and desires, forgoing immediate satisfaction in favour of long-term goals. It is resolute adherence to a regimen or course of action in order to achieve one’s goals.
Self-electrode – It is an electrode fabricated from the sample material and analyzed by emission spectroscopy.
Self-extinguishing – If set under fire the belt generates gases that extinguish the fire. Test procedures need that a minimum undamaged length remains after the belt has been set on fire.
Self-extinguishing resin – It is a resin formulation which burns in the presence of a flame but extinguishes itself within a specified time after the flame is removed.
Self-flow – It is the characteristic of a refractory castable to flow readily under its own weight without showing signs of segregation or separation.
Self-fluxing alloys – In thermal spraying, these are certain materials which ‘wet’ the substrate and coalesce when heated to their melting point, without the addition of a fluxing agent.
Self-fluxing sinter – it is also called basic sinter. It is the sinter in which sufficient flux is added in the sinter mix for producing slags of desired basicity (CaO/SiO2) in blast furnace taking into account the acidic oxides in the blast furnace burden.
Self-hardening steel – The preferred term is air-hardening steel. It is a steel containing sufficient carbon and other alloying elements to harden fully during cooling in air or other gaseous media from a temperature above its transformation range. The term is to be restricted to steels which are capable of being hardened by cooling in air in fairly large sections, about 50 millimeters or more in diameter.
Self-limiting characteristic – It is the characteristic of electrostatic powders to build only a limited quantity of surface film during application due to the build-up of a layer of charged particles which repels particles of like charge.
Self-lubricating bearings – These are a type of bearing designed to reduce friction and wear between moving parts without relying on external lubrication like grease or oil. They incorporate materials or mechanisms which provide a continuous or long-term supply of lubrication within the bearing itself. This eliminates the need for relubrication and reduces maintenance.
Self-lubricating material – It is a solid material which shows low friction without application of a lubricant. Examples are graphite, molybdenum di-sulphide, and poly-tetra-fluoro-ethylene. Taken in a broader context, the term can also refer to a composite material into which a lubricious species has been incorporated.
Self-operated instrument – It is that instrument which does not need any external power source for its operation. In such instruments the output energy is supplied by the input signal such as a dial indicator, or mercury in the glass type thermometer.
Self-potential – It is a technique used in geophysical prospecting, which recognizes and measures the minute electric currents generated by sulphide deposits.
Self-propagating high-temperature synthesis (SHS) – It is a method for producing materials through exothermic chemical reactions, where the heat released by the reaction sustains the reaction and allows it to propagate through the material. This process, also known as combustion synthesis, is a fast and efficient way to create several materials like ceramics, composites, and intermetallic compounds.
Self-quenching alloy – It is an alloy whose critical quench rate from its solution treatment temperature is slower than the rate of cooling in still air. This means that the alloying elements are held in solid solution even after cooling in still air.
Self-regulation – It is an industry sector assumes responsibility for environmental protection since it addresses their long-term interests and prevents more onerous external regulation.
Self-reinforced polymers (SRPs) – These are also called self-reinforced plastics. These are thermo-plastic composites where both the matrix and reinforcement are made from the same polymer. This means the fibres and the surrounding material are the same material, like poly-ethylene reinforcing a poly-ethylene matrix. These composites are also called single-polymer composites or homo-composites.
Self-reversal – In optical emission spectroscopy, it is the extreme case of self-absorption.
Self-selection – Self-selection is a problem which plagues survey study. Self-selection is a term used to describe what happens when survey respondents are allowed to deny participation in a survey. The belief is that respondents who are opposed or who are apathetic about the objectives of the survey refuses to participate, and their removal from the sample bias the results of the survey. Self-selection can also occur since respondents who are either strongly opposed or strongly supportive of a survey’s objectives respond to the survey.
Self-skinning foam – It is a urethane foam which produces a tough outer surface over a foam core upon curing.
Self-supporting steel stack – It is a steel stack of sufficient strength which needs no lateral support.
Self-tempering – It refers to a technique where the work-piece’s surface is only quenched, allowing the heat from the work-piece’s inside to quickly transfer to the quenched surface, reaching a tempering temperature and hence reducing brittleness. This process improves work-piece’s ductility while keeping its surface hard.
Self-testing – It normally refers to the ability of a system or component to test itself for faults or proper functioning. This can involve built-in mechanisms or procedures to diagnose issues and ensure the system operates as intended, potentially before external testing or during operation.
Selling – It is defined as ‘any of a number of activities designed to promote customer purchase of a product or service [which] can be done in person or over the phone, through e-mail or other communication media’. One of the studies describes personal selling as the ‘face-to-face interaction with one or more prospective purchasers for the purpose of making presentations, answering questions, and procuring orders’. As a result, direct communication with the customer is mostly done by the selling team. In the present day fast changing business environment, the selling practice has to take up new tools like e-commerce and m-commerce which nowadays partly substitute personal selling. Several studies have shown that selling is moving toward solution selling and has to focus even more on building relationships with each individual customer who is changing as well as from a single person as decision maker towards entire decision committees. Hence the traditional sales model is required to be replaced by key account management focusing on fewer strategic partners.
Selvage – It is the woven-edge portion of a fabric parallel to the warp.
Semi-analytical approach – It is a method which combines analytical and numerical techniques to solve complex problems, such as power flow analysis, by incorporating linear relations and managing non-linearities through methods like the convolution technique and Monte Carlo simulations. This approach is particularly useful in analyzing power systems.
Semi-arid zone – It is also known as a steppe or semi-desert. It is a climate type characterized by low rainfall, but not as low as a desert. It is a transition region between arid deserts and more humid regions, frequently receiving between 250 millimeters and 500 millimeters of rainfall annually. These regions are known for sparse vegetation, often grassland or scrubland, and face challenges like water scarcity, drought, and potential salinization.
Semi-automatic arc welding – It means arc welding with equipment which controls only the filler metal feed. The advance of the welding is manually controlled.
Semi-autogenous grinding (SAG) – It is a method of grinding rock into fine powder whereby the grinding media consist of larger chunks of rocks and steel balls.
Semi-automatic arc welding – It is the arc welding with equipment which controls only the filler metal feed. The advance of the welding is manually controlled.
Semi-automatic plating – It is the plating in which prepared cathodes are mechanically conveyed through the plating baths, with intervening manual transfers.
Semi-bright nickel plating – It is a type of nickel electroplating that produces a semi-lustrous, level, and ductile nickel deposit. Unlike bright nickel plating, it does not have a high mirror-like finish but offers excellent leveling and corrosion resistance, making it suitable for applications needing a smooth surface and good protection, especially in duplex nickel systems.
Semi-conducting materials – These are substances which are neither good conductors nor good insulators, with common examples including silicon and gallium arsenide. These materials can generate free-charge carriers through the introduction of controlled impurities, a process known as doping, which alters their electrical properties.
Semi-conductor – It is a solid crystalline material whose electrical resistivity is intermediate between that of a metal conductor and an insulator, ranging from around 10 to the power -3 ohm-centimeter to 10 to the power 8 ohm-centimeter, and is normally strongly temperature dependent. Semi-conductor is a substance with electrical conductivity between that of insulators and conductors; displays a negative temperature coefficient of resistance, and is also sensitive to light. The conductivity of semiconductors can readily be altered by trace quantities of other substances, leading to devices which are the foundation of nearly all modern electronics.
Semi-conductor device – It is a device which relies on substances with electrical conductivity between that of insulators and conductors, the controllable conductivity of these materials makes most of modern electronics possible.
Semi-conductor fabrication – It is the process of turning the raw source of silicon into transistors and integrated circuits.
Semi-conductor resistance thermometer – It measures temperature by sensing the change in electrical resistance of a semi-conductor material as it is exposed to different temperatures. Unlike metals, which normally see resistance increase with temperature, semi-conductors frequently show a negative temperature coefficient, meaning their resistance decreases as the temperature rises.
Semi continuous mills – These are those rolling mills in which some roll stands (normally the roughing stands) are reversing type while other rolling stands (normally finishing stands) constitutes continuous rolling.
Semi-crystalline – In plastics, it consists of materials which show localized crystallinity.
Semi-crystalline polymers – These are polymers which consist of both amorphous and crystalline regions, with crystallinity ranging from 10 % to 80 %. These polymers have ordered molecular structures and show precise melting points, transitioning to a low viscous liquid upon heating rather than melting gradually.
Semi-dry scrubbing system – It is a type of air pollution control device which uses a combination of dry reagents and water to remove pollutants from exhaust gas streams. Unlike wet scrubbers which use a liquid, and dry scrubbers which use only dry reagents, semi-dry scrubbers inject a humidified or sprayed lime slurry into a reactor vessel to capture acid gases. Cooling is frequently achieved by spraying water on the flue gas downstream of the sorbent injection point, which can reactivate the sorbent and improve efficiency.
Semi-endless rolling – It is a method where a continuous casting process produces a long slab, frequently 4 times to 6 times the length of a standard slab, which is then rolled continuously in a mill and cut into desired coil sizes before coiling. This process effectively decouples the casting and rolling operations, allowing for more flexibility in coil size and production. Semi-endless rolling needs an accumulation of evenly heated slab in the tunnel furnace since the discharge speed of the finishing train is higher than the casting speed.
Semi-finished steel – It consists of steel shapes, e.g., blooms, billets, or slabs, which later are rolled into finished products such as beams, bars, or sheet.
Semi-finished steel products – These are produced either by rolling or forging of ingots or by continuous casting, and normally are intended for conversion into finished steel products by rolling or forging. Their cross-section can be of various shapes with the cross-sectional dimensions remaining constant along the length. Semi-finished steel products have wider tolerances than those of the corresponding finished products, and the corners are more or less rounded. The side faces are sometimes slightly convex or concave, retaining rolling, forging or continuous casting marks, and can be partially or totally dressed by either a grinding tool are a scarfing torch. The semi-finished products can be further classified according to their shape, their cross-sectional dimensions and their use. Semi-finished products of square cross-section are normally categorized as (i) blooms, (ii) billets, (iii) slabs, (iv) blanks for sections, and (v) round blooms.
Semi-finisher – It is an impression in a series of forging dies which only approximates the finish dimensions of the forging. Semi-finishers are frequently used to extend die life or the finishing impression, to ensure proper control of grain flow during forging, and to assist in obtaining desired tolerances.
Semi-finishing – It is the preliminary operations performed prior to finishing.
Semi-flexible tower – It is designed so that it can use overhead grounding wires to transfer mechanical load to adjacent structures, if a phase conductor breaks and the structure is subject to unbalanced loads. This type of tower is useful at extra-high voltages, where phase conductors are bundled (two or more wires per phase). It is unlikely for all of them to break at once, barring a catastrophic crash or storm.
Semi-graphite material – This term is used to describe a product that is composed of artificial graphite particles mixed with carbonaceous binders such as pitch or tar and baked at carbonization temperatures of 800 deg C to 1,400 deg C. The resulting product is composed of carbon bonded graphite particles in which the graphite particles had previously been manufactured at temperatures close to 3,000 deg C but with binders which have only been baked in the 800 deg C to 1,400 deg C range. The resulting refractory product, a true carbon bonded graphite, shows higher thermal conductivity than the carbons but, because of the carbon binder, not as high as 100 % graphite. Thermal conductivities vary with baking temperature and can be increased by re-baking at higher temperatures. These refractory products are also conventionally baked, which results in a relatively porous material. However, these conventionally baked semi-graphites can also be densified and re-baked to carbonize the impregnated binder. Hence, porosity and, consequently, permeability can be reduced. Some conventionally baked semi-graphite products are also impregnated with or combined with silicon metal and silicon carbide for higher abrasion resistance and lower permeability. These refractory products, however, are intended for use in the bosh and stack.
Semi-graphitized carbon – It refers to a baked carbon which has been additionally heat-treated at a temperature of between 1,600 deg C to 2,400 deg C. This high temperature baking process begins to change the crystallographic structure of the carbon and alters its physical and chemical properties. However, since this additional heat treating occurs at temperatures below graphitization temperatures, the product is called semi-graphitized. This product contains carbon particles and a carbon binder which are both semi-graphitized. This is different than a semi-graphite product which is composed of graphite particles with a carbon binder. The resultant semi-graphitized carbon, in which both particles and binder are semi-graphitized, provides a material with higher thermal conductivity and chemical attack (from alkali or oxidation) resistance than either carbon or semi-graphite materials. This is because alkalis and zinc attack the binder material first and the semi-graphitized binder is more resistant to attack than the carbon binder of semi-graphite.
Semi-guided bend – It is the bend obtained by applying a force directly to the sample in the portion that is to be bent. The sample is either held at one end and forced around a pin or rounded edge or is supported near the ends and bent by a force applied on the side of the sample opposite the supports and midway between them. In some cases, the bend is started in this manner and finished in the manner of a free bend.
Semi-killed steel – It is the steel which is incompletely deoxidized and contains sufficient dissolved oxygen to react with the carbon to form carbon mono-oxide and hence offset solidification shrinkage.
Semi-monocoque – It refers to a stressed shell structure which is similar to a true monocoque, but which derives at least some of its strength from conventional reinforcement. Semi-monocoque construction is used for, among other things, aircraft fuselages, car bodies and motorcycle frames.
Semi-permanent mould – It is a permanent mould in which sand cores or plaster are used.
Semi-soft coking coal – It is a grade of metallurgical coal which is used in iron and steel plants, specifically in the process of making coke. It is a type of coal which, when heated without air, forms a coherent, but not strong, mass of coke. It is a coal which falls between hard coking coal and thermal coal in terms of its coking properties. It has a lower coking pressure and swelling index compared to hard coking coal but higher than thermal coal. This coal is frequently blended with other types of coking coal to achieve desired coke properties.
Semi-solid metal forming – It is a two-step casting / forging process in which a billet is cast in a mould equipped with a mixer which continuously stirs the thixotropic melt, thereby breaking up the dendritic structure of the casting into a fine-grained spherical structure. After cooling, the billet is stored for subsequent use. Later, a slug from the billet is cut, heated to the semi-solid state, and forged in a die. Normally the cast billet is forged when 30 % to 40 % is in the liquid state.
S-EMS – In a linear S-EMS, the electromagnetic coil is installed along one side of the strand and produces a vertical circulation liquid metal flow pattern in the strand. As the stirrer is placed along one side of the strand, it can be used for very different strand sizes. The increase in the central equiaxed crystal zone is obtained by the same mechanism as that obtained by the rotary stirrer. Inclusions, which normally are concentrated in a band close to the upper surface in curved mould continuous casting machines, are also more uniformly distributed. The rotary S-EMS which is placed in the optimum position high below the mould is sensitive to breakouts. S-EMS produces a stirring force which pushes the liquid steel horizontally along the cast product width and generates a butterfly type flow pattern in the liquid steel. When S-EMS can be placed behind the support rollers then it is not dependent on a minimum support roller diameter and hence in this case can be optimally placed along the strand from the metallurgical point of view. S-EMS when built into the support rollers needs a minimum roller diameter to include the iron core and windings. In this case the stirrer is placed at a distance from the meniscus and hence is less effective. S-EMS operates at low frequency to ensure good penetration of the stirrer force through the strand. As a result, the liquid steel has transverse stirring. S-EMS is normally used in combination with M-EMS. S-EMS can be of either linear or rotary type stirrer. Most common is the linear stirrer, which is easy to install and protect against heat radiation and possible breakouts. S-EMS promotes the formation of equiaxed structure. It promotes grain refinement in the cast product and reduces the shrinkage cavity, centre segregation, and internal cracks. It also removes superheat effectively.
Sendzimir mill – It is a type of cluster mill with small-diameter work rolls and larger-diameter backup rolls, backed up by bearings on a shaft mounted eccentrically so that it can be rotated to increase the pressure between the bearing and the backup rolls. The mill is used to roll precision and very thin sheet and strip.
Sensible heat – It is the heat which increases the temperature of water but does not change its phase / state.
Sensible heat flux – It refers to the transfer of heat energy between the earth’s surface and the atmosphere through conduction and convection, without a change in phase or state. It is the heat transfer which causes a temperature change in the air and is frequently measured with a thermometer. This flux is an important part of the earth’s energy budget, contributing to the overall balance of incoming and outgoing energy.
Sensitive tint plate – It is a gypsum plate which is used in conjunction with polarizing filters to provide very sensitive detection of birefringence and double refraction.
Sensitivity – It refers to an instrument’s ability to detect and respond to small changes in the quantity being measured, essentially the smallest detectable change in the measured variable. It denotes the smallest change in the measured variable to which the instrument responds. It is a desirable quality in the measurement. It is the ratio of the change in output (response) of the instrument to a change in the input or measured variable and is defined by delta input / delta output. All instruments have sensitivity to disturbance. All calibrations and specifications of an instrument are only valid under controlled conditions of temperature, and pressure etc. These standard ambient conditions are normally defined in the instrument specification. As variations occur in the ambient temperature or pressure etc., certain static instrument characteristics change, and the sensitivity to disturbance is a measure of the magnitude of this change. Such environmental changes affect instruments in two main ways, known as zero drift and sensitivity drift. Deflection factor or inverse sensitivity is the reciprocal of sensitivity.
Sensitivity analysis – It is an alternative analysis using a different model or different assumptions to explore whether one’s main findings are robust to different analytical approaches to the study problem.
Sensitivity of classification – In logistic regression, the probability of a case being classified as a case by the prediction equation.
Sensitivity drift – It is also known as scale factor drift. It defines the quantity by which the sensitivity of measurement of an instrument varies as ambient conditions change. It is quantified by ‘sensitivity drift coefficient’ which define how much drift there is for a unit change in each environmental parameter which the instrument characteristic is sensitive to. Several components within an instrument are affected by environmental fluctuations, such as temperature changes, e.g., the modulus of elasticity of a spring is temperature dependent.
Sensitivity of leak test – It is the smallest leakage rate which an instrument, method or system is capable of detecting under specified conditions.
Sensitivity of measurement – The sensitivity of measurement is a measure of the change in instrument output which occurs when the quantity being measured changes by a given quantity. Hence, sensitivity is the ratio. The sensitivity of measurement is hence the slope of the straight line drawn between the output reading and measured quantity.
Sensitivity studies – These are a way to investigate how the output of a model or system changes in response to variations in its inputs or parameters. Basically, it is about understanding which factors are most critical in determining the outcome and how much those factors influence the results.
Sensitization – In austenitic stainless steels, it is the precipitation of chromium carbides, normally at grain boundaries, on exposure to temperatures of around 540 deg C to 850 deg C, leaving the grain boundaries depleted of chromium and hence susceptible to preferential attack by a corroding medium. Welding is the most common cause of sensitization. Weld decay (sensitization) caused by carbide precipitation in the weld heat-affected zone leads to intergranular corrosion.
Sensitizing heat treatment – It is a heat treatment, whether accidental, intentional, or incidental (as during welding), which causes precipitation of constituents at grain boundaries, frequently causing the alloy to become susceptible to intergranular corrosion or intergranular stress-corrosion cracking.
Sensor – It is a device or system which converts some physical event into an electronic signal, for further use in measurement or control. Sensor is also a device in a conveyor system which detects and responds to specific conditions, such as material presence or temperature. Regular inspections are necessary to ensure accurate sensing and prevent false readings.
Sensor bandwidth – It refers to the range of frequencies over which a sensor can accurately measure input variables without introducing significant errors. A sensor with limited bandwidth can produce errors when measuring rapidly changing input quantities, as its output will change gradually instead of responding instantaneously.
Sensor devices – These are instruments which implement an ‘Input’ function by sensing physical alterations in characteristics, such as force or heat, and converting these changes into usable electrical signals.
Sensor electrode – It is a component of an electro-chemical sensor which facilitates the detection of specific chemical species through oxidation or reduction currents, frequently utilizing modifications to improve sensitivity and selectivity. These electrodes are normally made from carbon materials, such as carbon fibres or activated carbon fibrers, to improve performance in different applications.
Sensor loop – It is the loop made of conductive material embedded in the belt top or bottom cover to prevent slitting. If they are cut, the conveyor drive stops.
Sensors – Sensors are those instruments which carry out the functions of vision, hearing etc. These instruments measures temperature, level, flow, composition etc. These are thermocouples, differential pressure meters, gas analyzers etc.
Separable flange – It is a flange which fits over a valve body flow connection. It is normally held in place by means of a retaining ring.
Separate fired burners – These burners are industrial heating systems where fuel is burned in a separate combustion chamber, with the heat then transferred to a process fluid. These burners utilize many fuel types like natural gas, propane, oil, and coal, and are crucial in industries. The key concept is the separation of the combustion process from the application, allowing for precise heat transfer and control. In these burners, the fan, pump and / or other fundamental parts of the burner are separate from the main body (head).
Separation by physical and chemical characteristics – Separation by physical and chemical characteristics utilizes colour, density, magnetic, spark, chemical and spectroscopic testing. Scrap materials are typically identified by skilled operators (sorters) using a limited number of physical and chemical tests. These tests rely on object recognition by colour, apparent density, reaction with chemical reagents, chemical analysis, magnetic properties, nature of spark pattern when ground by an abrasive wheel, and spectrographic analysis.
Separation strength – It is the strength needed to separate cover and ply and ply from ply.
Separator – In rolling-element bearings, it is the part of a cage which lies between the rolling elements. This term is sometimes used as a synonym for cage. In composites, separator is a permeable layer which also acts as a release film. Porous Teflon-coated fibre-glass is an example. Separator is frequently placed between lay-up and bleeder to facilitate bleeder system removal from laminate after cure. In a steam distribution system, separators are devices which remove water droplets and other impurities from the steam, ensuring the steam is dry and of high quality before it is used. They are crucial for preventing damage to downstream equipment like turbines and for maintaining the efficiency of the system.
Sequencing – It is the controlled order of operations in a conveyor system, ensuring proper coordination of different components. Regular checks are necessary to maintain the sequencing logic and prevent issues like jams or misalignments.
Sequential engineering – It is an older style of product development in which design decisions are made in a rigid linear pattern, e.g., all decisions on functionality are made before any decisions of production method, etc. This is being supplanted by concurrent engineering.
Sequential experimentation – It is also known as sequential analysis or sequential hypothesis testing. It is a method where the sample size is not predetermined, but rather data is evaluated as it is collected, and sampling continues or stops based on a predefined rule. This contrasts with traditional hypothesis testing, where the sample size is fixed in advance.
Sequestration – It refers to the process of capturing and storing atmospheric carbon di-oxide (CO2). This process aims to reduce the quantity of carbon di-oxide in the atmosphere and mitigate climate change by storing it in different forms, including plants, soils, geologic formations, and the ocean. Essentially, it is about removing carbon di-oxide from the atmosphere and preventing it from contributing to the green-house effect. Carbon sequestration involves capturing carbon di-oxide, which can be done through different methods like capturing it directly from industrial sources or removing it from the atmosphere. Once captured, the carbon di-oxide is then stored, either naturally or through human intervention, in different sinks. There are two main types of carbon sequestration namely (i) biological which refers to the natural process where plants, trees, and other organisms absorb carbon di-oxide from the atmosphere during photosynthesis and store it in their biomass, and (ii) geological which involves storing carbon di-oxide in underground geologic formations, like depleted oil and gas reservoirs or deep saline formations.
Sequestration and chelation – It mean to inactivate calcium, magnesium, and iron salts in water so that they do not interfere with cleaning. Chelated alkaline compounds can remove oxides and rust from steel surfaces, eliminating the need for acids that may react with the metal to cause hydrogen embrittlement.
Serial communication – It is the transmission of data as a single series of bits over a communication path.
Serial dilution – It is the step-wise dilution of a substance in solution, either by using a constant dilution factor, or by using a variable factor between dilutions. If the dilution factor at each step is constant, this results in a geometric progression of the concentration in a logarithmic fashion. A ten-fold serial dilution can be 1 M, 0.1 M, 0.01 M, 0.001 M and so on. Serial dilutions are used to accurately create highly diluted solutions as well as solutions for experiments resulting in concentration curves with a logarithmic scale. A tenfold dilution for each step is called a logarithmic dilution or log-dilution, a 3.16-fold dilution is called a half-logarithmic dilution or half-log dilution, and a 1.78-fold dilution is called a quarter-logarithmic dilution or quarter-log dilution.
Serial sectioning – It is a metallographic technique in which an identified area on a section surface is observed repeatedly after successive layers of known thickness have been removed from the surface. It is used to construct a three-dimensional morphology of structural features.
Series and parallel circuits – These are electrical circuits where current passes through multiple elements either one after the other, or side by side, like the rungs of a ladder, or both.
Series circuits – These are sometimes referred to as current-coupled. The current in a series circuit goes through every component in the circuit. Hence, all of the components in a series connection carry the same current. A series circuit has only one path through which its current can flow. Opening or breaking a series circuit at any point causes the entire circuit to ‘open or stop operating, e.g., if even one of the light bulbs in an older-style string of lights burns out or is removed, the entire string becomes inoperable until the faulty bulb is replaced.
Series motor – It is a type of electric motor where the starting rheostat is connected in series with the motor, and it features a resistance around twice that of the armature resistance. This motor is normally used in applications such as cranes and hoists, where the starting resistance is also utilized for speed control.
Series resistor (SR) – It is a small resistor connected in series with another resistor to achieve offset voltage compensation in a circuit. It is used to null the offset voltage at a specific temperature, though the offset can reappear with temperature changes.
Series welding – It is the resistance welding in which two or more spot, seam, or projection welds are made simultaneously by a single welding transformer with three or more electrodes forming a series circuit.
Series-wound motor – It is a type of electric motor where the field windings and armature windings are connected in series, meaning the same current flows through both. This design results in high starting torque and speed that decreases with load.
Serpentine – It is a greenish, metamorphic mineral consisting of magnesium silicate.
Serpentine spring – It also known as a zig-zag or no-sag spring. It is a type of spring used in those applications where a flexible, yet supportive structure is needed. It is characterized by its wavy, lateral zig-zag pattern, which provides a balance of flexibility and resistance to sagging.
Serpentine weave – It is a series of reversing lateral bows in coil products. This condition is caused by a weaving action during an unwinding or rewinding operation.
Serrated rubber – It refers to rubber which has a notched or toothed edge, similar to a saw blade. This serrated design can be used for several purposes, such as increasing friction, providing a tighter seal, or aiding in material removal.
Server – It is a powerful computer or software system which stores, manages, and delivers web pages and related content to users’ devices (like web browsers) over the internet. Essentially, it acts as a central hub which processes requests from clients (users) and sends back the requested information. Sever provides resources, data, services, or programmes to other computers (clients) over a network. Basically, it is a machine which shares its capabilities and resources with other devices.
Serviceability limit state (SLS) – It refers to the condition beyond which a structure no longer performs its intended function or service, even if it has not collapsed. It focuses on maintaining the usability, comfort, and appearance of a structure under normal service conditions, rather than its ultimate strength or ability to resist collapse. It is the state of design beyond which a structural system loses operationally its serviceability for the actual service load that the structure is subjected to.
Service centre – It is a catchall name for an operation which buys a product, frequently processes it in some way and then sells it in a slightly different form. A service centre is distinguished from an end-user by the fact that, unlike an end-user, a service centre sells the product, not a fabricated product. Service centres are manufacturers to the extent that they add labour to the product by providing a service.
Service factor – It is the ratio between the working tension and the belt breaking strength (f.i. 10:1), not considering the splice efficiency.
Service life – It is the expected lifespan of conveyor components or the entire conveyor system. The belt service life depends on several influences like type and quality of the belt and the splice, feeding situation, lump size, weight and shape, tonnage, bendings, velocity, pulley lagging, maintenance, safety factor, starting and stopping etc., and the right monitoring system. Periodic assessments are crucial to evaluate wear, fatigue, and other factors affecting the service life of conveyor elements.
Service loop – It is a coiled arrangement of electrical cables designed to provide flexibility and movement without inducing damage. Regular examinations are essential to validate the integrity and operational effectiveness of service loops, mitigating the risk of cable wear or breakage.
Service test – It is a test in which the product is evaluated under actual service conditions.
Service water – It is the general-purpose water which has been or has not been treated for a special purpose.
Servo control – It is a system which utilizes a controller to generate motion paths and respond to external changes, typically involving a feedback mechanism to correct errors and maintain control over speed and position. It can operate in both open loop and closed loop configurations, with closed loop systems providing more accurate control for complex motion profiles.
Servo-hydraulic test system – It is a testing machine which uses hydraulic power and servo control to precisely apply loads or forces to materials or components. It is used for static and dynamic fatigue testing, allowing engineers to study material behaviour under several loads, including fatigue, impact, and high-force applications.
Servo mechanism – It is also called servo system. It is a control system for the position and its time derivatives, such as velocity, of a mechanical system. It includes frequently a servo motor, and uses closed-loop control to reduce steady-state error and improve dynamic response. In closed-loop control, error-sensing negative feedback is used to correct the action of the mechanism. In displacement-controlled applications, it includes normally a built-in encoder or other position feedback mechanism to ensure the output is achieving the desired effect. Following a specified motion trajectory is called servoing, where ‘servo’ is used as a verb. The servo prefix originates from the Latin word servus meaning slave. The term correctly applies only to systems where the feedback or error-correction signals help control mechanical position, speed, attitude or any other measurable variables, e.g., an automotive power window control is not a servo-mechanism, as there is no automatic feedback which controls position, the operator does this by observation. By contrast a car’s cruise control uses closed-loop feedback, which classifies it as a servo mechanism.
Servo motor – It is a rotary or linear actuator which allows for precise control of angular or linear position, velocity, and acceleration in a mechanical system. It constitutes part of a servo-mechanism, and consists of a suitable motor coupled to a sensor for position feedback and a controller (frequently a dedicated module designed specifically for servo motors). Servo motors are not a specific class of motor, although the term servo motor is frequently used to refer to a motor suitable for use in a closed-loop control system. Servo motors are used in applications such as robotics, computer numerical control (CNC) machinery, and automated manufacturing.
Servo piston – It is a component which operates a main valve through mechanical linkages, controlling the flow of oil to power cylinders.
Servo pump – It is a type of pump which utilizes a by-pass valve to direct oil from the delivery to the suction line at startup, hence reducing the starting load.
Set – It is the deformation or strain remaining in a previously stressed body after release of load. It is also a flow property of porcelain enamel slip affecting the rate of draining, residual thickness, and uniformity of coating. In statistics, a set is a well-defined collection of distinct objects or elements, grouped together based on a shared property or characteristic. These elements can be numbers, letters, symbols, or even other sets. Sets are used in statistics to represent data, classify observations, and perform operations like union and intersection. In composites, set is the irrecoverable or permanent deformation or creep after complete release of the force producing the deformation. It also means to convert an adhesive into a fixed or hardened state by chemical or physical action, such as condensation, polymerization, oxidation, vulcanization, gelation, hydration, or evaporation of volatile constituents.
Set control limits – Understanding the operating parameters allows the ability to define the limits of the measurable parameters in the control system.
Set down – It is a non-standard term for upset.
Set high – It is vertical spacing which allows rollers to be attached above frame rails.
Set lead / lag criteria – Depending on the control logic used in the process, there can be lag times associated with the measurement of the operating parameters. Setting lead / lag times compensates for this effect and allow for accurate control.
Set low – It is the vertical spacing which allows the roller to be mounted below the top of the frame rails.
Set-point – It is the target or desired value for a specific variable within a control system. This variable can be anything measurable, such as temperature, pressure, flow rate, or position. The control system is designed to maintain the process variable at this set-point value.
Set point temperature – It refers to the pre-determined indoor temperature settings for heating and cooling systems, which can be adjusted to optimize energy consumption.
Set pressure – It is the pressure at which a safety valve is calibrated to open and allow fluid to pass, typically above the normal operating pressure of the system.
Setting time – It is the elapsed time from the first addition of liquid during the mixing of the refractory castable until the time that the refractory castable has developed enough strength so that forms can be removed without any slumping or deformation.
Setting-up agent – It is an electrolyte used to increase the measured pick-up of a slip. It is also known as set-up agent.
Settlement – It is the downward movement or the sinking of a structure’s foundation. It is mostly caused by changes in the underlying soil, such as drying and shrinking, wetting and softening, or compression due to the soil being poorly compacted when construction started. Some settlement is quite normal after construction has been completed.
Settling – It consists of separation of solids from suspension in a fluid of lower density, solely by gravitational effects. It is also a process for removing iron from liquid magnesium alloys by holding the melt at a low temperature after manganese has been added to it.
Settling pond – It is an open lagoon into which waste-water contaminated with solid pollutants is placed and allowed to stand. The solid pollutants suspended in the water sink to the bottom of the lagoon and the liquid is allowed to overflow out of the enclosure.
Settling rate – It is the velocity at which a particle falls through a fluid, influenced by factors such as particle size, density differences between the particle and fluid, and the viscosity of the fluid. It is calculated from the balance of gravitational, buoyant, and viscous forces acting on the particle.
Settling tank – It is also known as a sedimentation tank. It is a container where liquids are held to allow suspended solids to settle to the bottom under the influence of gravity. It is a conical-bottom tank designed for the accumulation and removal of sludge from water, typically facilitating the separation of solids through gravity, with flow rates varying based on particulate load. It operates intermittently to manage higher solids concentrations, achieving varying removal efficiencies. This process is a crucial step in water and wastewater treatment, helping to separate solids from the liquid for further purification.
Settling velocity – It is the speed at which individual particles move through a fluid, which can be determined by timing their movement between two fixed points in a vertical tube of water. It is important for calculating hydraulic diameter, sphericity, and understanding the stratification behaviour of mixed-media beds during processes like backwashing.
Set up – It means to harden, as in curing of a polymer resin.
Severe accident – It is an unexpected, unplanned event which causes substantial pain, worry, or damage, and is frequently associated with serious consequences such as life-threatening injuries, major damage to property or infrastructure, or potentially catastrophic incidents like a nuclear meltdown. The specific implications of a severe accident can vary depending on the context, ranging from severe injuries in a car crash to substantial core damage in a nuclear power plant.
Severe cold heading, cold extrusion quality wire rod – It is used for severe single step or multiple steps cold forming where intermediate heat treatment and inspection are not possible. Wire rod of this quality is produced with carefully controlled production practices and rigid inspection practices to ensure the needed degree of internal soundness and freedom from surface defects. Fully killed fine grain steel is normally needed for the most difficult operations. Normally, the wire made from this quality wire rod is spheroidize-annealed, either in process or after drawing finished sizes.
Severe defect – It is a fault or flaw which has a substantial, negative impact on the functionality, safety, or expected performance of a system, product, or material. The classification of ‘severe’ is context-dependent, but it normally implies a defect which is very serious, causes major inconvenience or danger, or renders a core function inoperable, as opposed to a minor cosmetic issue.
Severe plastic deformation (SPD) – It is a metal-working process which involves subjecting a bulk metal to extremely large plastic strains, resulting in the formation of ultrafine-grained or nano-crystalline micro-structures. These techniques aim to improve the mechanical properties of materials by creating a high density of defects and refining the grain size.
Severe wear – It is a form of wear characterized by removal of material in relatively large fragments. Severe wear is an imprecise term, frequently used in research, and contrasted with mild wear. In fact, the phenomena studied usually involve the transition from mild to severe wear and the factors which influence that transition. With metals, the fragments are normally predominantly metallic rather than oxidic. Severe wear is frequently associated with heavy loads and / or adhesive contact.
Severing unit – It consists of cutting torches or mechanical shears which are needed to cut the solidified strand into pieces of desire length for removal and further processing.
Severity – Severity of a hazard is the degree of harm which a hazard can create if it occurs.
Severity factor – It is a symbolic measure of the seriousness of the effect of a potential failure, assessed on a scale from 1 (no danger) to 10 (critical). It evaluates the seriousness of the failure effect rather than the mode of failure, needing agreement on evaluation criteria among the analysis team.
Severity of quench – It is the ability of quenching medium to extract heat from a hot steel work-piece. It is expressed in terms of the Grossmann number (H).
Severity rate – It is thousands of times the total number of days lost divided by the total number of hours worked. Values for severity rates are correlated to frequency on lost time injury frequency (LTIF). For example, if the average number of lost days for all lost time injuries remains constant for a certain-period then the severity rate is directly proportional to the lost time injury frequency. So, for evaluating severity rates, a person is always to consider the change in lost time injury frequency before conclusions are drawn.
Sewage – It is the liquid waste from domestic, commercial, and industrial establishments.
Sewage treatment – It is the processing of waste-water for the removal or reduction of contained solids or other undesirable constituents.
Sewage sludge treatment – It refers to the application of biological, chemical, and physical processes to reduce water content and eliminate hazards associated with sewage sludge, including pathogens and heavy metals. This treatment can involve different operations such as thickening, stabilization, conditioning, dewatering, and thermal reduction, impacting the biological and physical properties of the final product.
Sewage treatment plant (STP) – It, is a facility designed to remove contaminants from waste-water and sewage, making it safe for discharge into the environment or for reuse. These plants use a combination of physical, chemical, and biological processes to treat wastewater from different sources. The main goal is to produce clean water (effluent) and manage by-products like sludge.
Sewer – It is a system of pipes, drains, pumping works, equipment, structures, and other things used for the collection, transportation or disposal of waste-water, but does not include any building drain, plumbing, or building sewer.
SFAIRP– It means ‘So-Far-As-Is-Reasonably-Practicable’.
SG iron – It is the term used for ductile or nodular iron. SG means spherulitic or spheroidal graphite.
S-glass – It is a magnesium alumino-silicate composition which is especially designed to provide very high tensile strength glass filaments. S- glass and S-2 glass fibres have the same glass composition but different finishes (coatings). S-glass is made to more demanding specifications, and S-2 is considered the commercial grade.
Shaded-pole motor – It is an alternating current single-phase motor which produces a rotating magnetic field by a turn of wire around part of a field pole.
Shadow angle – In shadowing of replicas, it is the angle between the line of motion of the evaporated atoms and the surface being shadowed.
Shadow cast replica – It is a replica that has been shadowed. See also replica and shadowing .
Shadowing – It is the directional deposition of carbon or a metallic film on a plastic replica so as to highlight features to be analyzed by transmission electron microscopy. Very frequently it is used to provide maximum detail and resolution of the features of fracture surfaces.
Shadow mask – It is a thermal spraying process variation in which an area is partially shielded during the thermal spraying operation, hence permitting some overspray to produce a feathering at the coating edge.
Shadow matter – It is a hypothetical counter-part to ordinary matter which mirrors the properties of ordinary matter but interacts with it only through gravity or weak interaction.
Shadow microscope – It is an electron micro-scope which forms a shadow image of an object using electrons emanating from a point source located close to the object.
Shadow pricing – It is the practice of assigning a monetary value to a good, service, or resource which does not have a readily available market price. This estimated value, known as the shadow price, helps in evaluating projects, policies, or resource allocation decisions where the true cost or benefit is not directly observable in the market.
Shaft – It consists of a vertical or inclined excavation in rock for the purpose of providing access to an ore-body. It is normally equipped with a hoist at the top, which lowers and raises a conveyance for handling workers and materials. Shaft also known as drive shaft is a mechanical component which transmits power from an electric motor to an impeller, frequently supported by bearings to reduce friction and vibration. It can enter a process vessel different orientations, including top, bottom, or side, and can need multiple impellers at different levels depending on the tank’s dimensions. In conveyor system, shaft is a dynamic rotating rod or spindle which is integral for providing support and transmitting motion within conveyor components. Regular inspections are vital to evaluate the condition, alignment, and overall integrity of the shaft, safeguarding against potential disruptions. In case of a valve, shaft is the portion of a rotary control valve assembly corresponding to the valve stem of a globe valve. Rotation of the shaft positions the disk or ball in the flow stream and controls flow through the valve. Blast furnace stack is frequently being called as shaft.
Shaft alignment – It is the precise adjustment of conveyor shafts to ensure proper alignment and prevent issues such as increased wear or power transmission inefficiency. Regular checks and adjustments become imperative to maintain shaft alignment.
Shaft coupling – It is a device which is used to connect two shafts in a conveyor system, transmitting motion and torque. Ongoing inspections are essential to assess coupling conditions, alignment, and overall functionality.
Shaft diameter – It is the specific width of a conveyor shaft, tailored to the demands of its unique application. Consistent measurements are vital to appraise shaft diameter, guaranteeing harmonious integration with conveyor components.
Shaft extension – It is the extended segment of a conveyor shaft projecting beyond its junction point. Regular assessments are critical to confirm the steadfastness, alignment, and holistic soundness of shaft extensions.
Shaft furnace – A shaft furnace is a refractory lined furnace which has an upright working chamber of circular, elliptical, or rectangular cross section in which a fixed bed (or descending column) of solids is maintained, and through which an ascending stream of hot gas is forced. It is used to smelt or roast lumped materials. The heat required for smelting or roasting process is produced by the combustion of a fuel either directly in the furnace or in an external firebox from which the combustion products are supplied to the furnace. There is counter current movement of gases and the solids in the furnace. In this furnace, gravity conveys solids and liquids to the bottom and by-product gases to the top. Examples are cupolas, blast furnaces, and lime kilns.
Shafting – It is the comprehensive designation for all the shafts strategically used throughout a conveyor system. Periodic evaluations are indispensable to gauge the condition, alignment, and holistic well-being of the entire shafting network within the conveyor.
Shaft key – It is a securing device employed to fasten the link between a shaft and a conveyor component, averting slippage or misalignment. Regular inspections are imperative to validate the appropriateness and condition of shaft keys, ensuring robust connections.
Shaft mount reducer – It is a type of reducer directly mounted on a conveyor shaft to decrease speed and increase torque. Consistent checks are crucial to verify the proper functioning, lubrication, and alignment of shaft mount reducers.
Shaft run-out – It is twice the distance which the centre of a shaft is displaced from the axis of rotation, i.e., twice the eccentricity.
Shaft seal – It is a seal which is used to protect conveyor components, such as bearings, from contaminants and prevent lubricant leakage. Ongoing checks are essential to verify the integrity and effectiveness of shaft seals.
Shaft sleeve – It is a protective sleeve installed over a conveyor shaft to improve durability and prevent wear. Regular inspections are necessary to assess sleeve condition and ensure proper protection of the shaft.
Shaft sprocket – It is a sprocket directly mounted on a conveyor shaft for power transmission. Periodic assessments are crucial to evaluate sprocket condition, alignment, and overall integrity.
Shaft torque – It is the twisting force or rotational moment applied to a shaft, representing its resistance to twisting or the useful work it can perform. It is a critical performance metric in devices like direct current motors, where it indicates the force available to turn a load or the rotational force generated by a component. Shaft torque can be measured in units like Newton-meters and is fundamentally different from power, which measures energy per second.
Shaft type – It is the specific design and configuration of a conveyor shaft, which can vary based on the intended application. Routine checks become imperative to assess shaft type and compatibility with conveyor components.
Shaft vibration – It is the rhythmic or oscillating movement of a conveyor shaft extending beyond standard parameters. Continuous vigilance is essential to identify and rectify any heightened shaft vibration, ensuring the stability and dependability of the entire system.
Shaft voltage – It is an objectionable stray voltage which appears on the rotating part of an electrical machine, very deleterious to supporting bearings.
Shake-down (of surface layers) – It is the establishment of a state of stress in which no further plastic flow occurs.
Shake-out – It is the removal of castings from a sand mould. The shake-out operation is for the separation of the casting from the mould and core sand. It is the stage in the casting process where the sand from the muold and core is cleaned off of the newly formed castings through vigorous vibration. It is the first step to finishing a casting after it has solidified and cooled in the mould. A considerable amount of energy is needed to remove the adhering layer of sand and oxide (that formed under the effect of heat from the metal which was poured into the mould) and also to separate the casting from lumps of sand still strong bonded together.
Shake-out machinery – It is the equipment for mechanical removal of castings from moulds.
Shaker-hearth furnace – It is a continuous type furnace which uses a reciprocating shaker motion to move the parts along the hearth.
Shaking table – It is also known as a gravity concentrating table. It is a beneficiation equipment which utilizes mechanical vibration and water flow to separate mineral particles based on their density. It is normally used in ore beneficiation to recover valuable minerals like gold, iron, manganese, and others. Shaking tables have wide range of application in gravity treatment of iron ores. These tables are normally used in cleaning and scavenging circuits. Feed size applicability is in the range of 0.3 millimeter to 1 millimeter.
Shale – It is the sedimentary rock formed by the consolidation of mud or silt.
Shale gas – It is the natural gas which is trapped in organic-rich shale rock formations. Unlike conventional natural gas, shale gas is considered an ‘unconventional’ resource since it is held in shale, a very low-permeability rock, needing specialized drilling and extraction techniques like horizontal drilling and hydraulic fracturing (fracking) to release it. This process involves injecting pressurized water, sand, and chemicals into the well to create fissures in the rock, allowing the gas to flow out.
Shales – These are abrasive particles of plate-like shape. The term is applied particularly to diamond abrasives.
Shallow foundation – It is a type of foundation which transfers structural load to the Earth very near to the surface, rather than to a subsurface layer or a range of depths, as does a deep foundation. It is normally used when the bearing capacity of the surface soil is adequate to carry the loads imposed by a structure. Customarily, a shallow foundation is considered as such when the width of the entire foundation is larger than its depth. In comparison to deep foundations, shallow foundations are less technical, hence making them more economical and the most widely used for relatively light structures.
Shallow junctions – These are defined as p–n junctions which are fabricated with minimal depth to meet the demands of miniaturized electronic devices, allowing for improved performance in ultra-shallow junction technology.
Shallow pitting corrosion – It is also called uniform corrosion. It is a form of corrosion where the surface is removed almost evenly. The partial reactions (metal dissolution and oxygen reduction) are statistically distributed over the surface, leading to more or less homogenous dissolution of the metal and uniform formation of corrosion product (red rust). The extent of this form of corrosion can usually be well estimated on the basis of previous experience. The rate of corrosion is usually given in micrometers per annum. Using these average values, it is possible to calculate the life expectancy of a component, and hence to improve its life expectancy by increasing its thickness. Uniform corrosion takes place on unprotected carbon steel and on galvanized steel under atmospheric conditions. However, in reality, purely homogenous corrosion attack is unlikely to take place. There are always areas, especially on complex metal parts, which will corrode faster than others leading to a more or less rough surface with an irregular covering of corrosion.
Shallow water table – It is a groundwater level which is located at a depth less than the depth of typical foundation embedment, which can affect the effective weight of submerged foundations and lead to increased eccentricity in load distribution.
Shank – It is the portion of a die or tool by which it is held in position in a forging unit or press. It is also the handle for carrying a small ladle or crucible. Shank is also the main body of a lathe tool. If the tool is an inserted type, the shank is the portion which supports the insert. In case of a fastener, shank is the cylindrical part of a fastener which extends from the underside of the head to the starting thread.
Shank-type cutter – It Is a cutter which is having a straight or tapered shank to fit into a machine-tool spindle or adapter.
Shape – It refers to the ability of a material to be precisely formed or moulded into a desired shape. This includes both the material’s inherent properties which influence its formability and the processes used to manipulate it. Shape of an individual granule can be angular, spherical, acicular, ovaloid, flaky, or slabby. They can be mixed in the same material. This term is no longer recommended. The term profile is preferred.
Shape accuracy – It refers to how closely the actual shape of a product matches its intended design or specification. It is a crucial factor in determining the quality and functionality of the manufactured product. Essentially, it is about how well the product’s surfaces align with the specified shape, such as roundness, flatness, column, conical, or linear features.
Shape and orientation factor (SOF) of the flaw – In general, the shape and orientation factor is a complex function of the shape and orientation of the flaw relative to the eddy current fields. However, there are two special cases of interest for which the shape and orientation factor is relatively simple. These cases are the sphere and the circular disk, or penny flaw. For the spherical void, the shape and orientation factor is 1, and the volume is (4/3 pi) x a cube, where ‘a’ is the radius of the sphere. For a circular disk oriented with the circle perpendicular to the eddy current field direction, the product of the volume and the shape and orientation factor is (16/9) x a cube. The same theory can also be applied to surface counterparts of these two flaws namely the hemisphere and the half disk, or half penny flaw. In both of these cases, the product of the volume of shape and orientation factor is half that of their sub-surface counterparts, because of the volume being halved.
Shape casting – It is a manufacturing process where molten metal is poured into a mould to create a finished product with a complex shape, frequently used when other methods are impractical or uneconomical. The process involves creating a mould with a cavity representing the desired shape, pouring in the molten metal, allowing it to solidify, and then removing the finished casting.
Shape control system – It can be divided into pre-setting control system and closed-loop control system according to the control sequence, and the modelling of shape control system includes mechanism and intelligent models. Presetting control is a predictive control, and closed-loop control is a monitoring control. The two control systems complement each other and ensure the strip shape quality. Shape pre-setting control is the foundation of closed-loop control. Closed-loop control precision, speed, and stability are directly influenced by the precision of pre-setting control.
Shape correcting – Rolling, heating, and quenching steel sheets frequently affect the dimensions of the steel. Levelers, temper mills, and edge-trimmers rework the processed steel to match customer specifications.
Shape correction with flatteners – Both two-high and four-high flatteners can control and eliminate coil set and cross bow but cannot eliminate buckle and wavy edge. A flattener can reduce twist in a narrow strip, but eliminating high-degree twist can also introduce another type of shape defect. Normally, flatteners cannot correct camber. However, a flattener with tilting adjustment ability along the longitudinal centre-lines of its upper frame can reduce and eliminate a small degree of camber in a strip. A deliberate mis-alignment of a pull-through flattener to the line can eliminate a camber in a narrow strip (less than 50 mm). Auxiliary side push rolls near the entry side of a flattener are used for camber correction in a narrow strip (less than 100 millimetres wide with thickness higher than 0.6 millimetres).
Shape correction with roller levellers – Roller levellers can control and correct not only coil set and cross bow, but also wavy edges and buckles. This is since they have the ability to control the deflection of their work rolls so that one portion of the strip can be subjected to more deformation than another. In the case of the centre buckle or longer centre than the edges, the edges are to be stretched more than the centre until the same length is achieved between them. The back-up rolls in the leveller are to be set tighter on the edges than the centre so that bending on the edges has a higher degree of bending than that in the centre. In contrast, if the strip has wavy or loose edges, the centre is to be stretched more until it has the same length as the edges. The back-up rolls are to be set up closer in the centre than on the edges.
Shape correction with tension levellers – Tension levellers can correct coil set, cross bow, buckle, and wavy edges, as well as twist and camber. A tension-leveller applies tension to the strip as it alternately passes over and under a series of very small-diameter, backed-up rolls. When used correctly, tension levelling has proved to be the most versatile tool commercially used for improving shape of coiled material.
Shape defects – They refer to variations or imperfections in the product’s form, outline, or dimensions, deviating from the intended design or specifications. These defects can manifest as irregularities, distortions, or inconsistencies in the product’s shape, potentially impacting its functionality, aesthetics, or usability. Examples of shape defects are Shape defects are rhomboidity and longitudinal depression ovality.
Shape design parameter – It is a design parameter which describes the boundary position in a numerical (finite element method, FEM) model, and hence defines nodal location. Optimizing a shape design parameter can need that the entire finite element model be remeshed.
Shaped insulating refractory – It consists of shaped refractory having a true porosity of not less than 45 % by volume. These products are characterized by low thermal conductivity and low heat capacity.
Shaped products – These products refer to the material which has been manufactured into specific geometric forms, like I-beams, H-beams, channels, angles, and several other shapes, for use in construction and other industries. These shapes are created through processes like hot rolling or cold forming, where the material is manipulated into the desired profile.
Shaped refractories – These are those refractories which have fixed shapes when delivered to the user. These are heat-resistant materials which are pre-formed into specific shapes, such as bricks, before being used in high-temperature applications. Shaped refractories can be further categorized into standard shapes (e.g., standard bricks) and special shapes (e.g., wedge-shaped bricks). Standards shapes have dimensions which are conformed to by most refractory manufacturers and are normally applicable to kilns and furnaces of the same type. Special shapes are specifically made for particular kilns and furnaces. These shapes are not applicable to another furnaces or kiln of the same type. Shaped refractories are almost always machine-pressed, hence, high uniformity in properties is expected. Special shapes are very frequently hand-moulded and are expected to show slight variations in properties. Shaped refractories are distinct from unshaped or monolithic refractories, which are applied as a powder or mass and form a shape in place.
Shape factor – In structural engineering, it is a dimensionless value which represents the ratio of the plastic moment capacity of a section to its yield moment capacity. It essentially indicates how much extra load a section can carry beyond its initial yield point before reaching full plastic deformation. The shape factor is a function of the cross-section’s geometry and is represented by ‘S’.
Shape generation process – It is a mass-reducing process in which the shape of the part is determined by the pattern of relative motion between the cutting tool and the part. Shape information is impressed by the process.
Shapeless refractories – These are refractory materials without a fixed shape, Examples are mortar, castable, gunning mixture, and plastic etc.
Shape memory alloy (SMA) – This term is applied to that group of metallic materials which demonstrate the ability to return to some previously defined shape or size when subjected to the appropriate thermal procedure. Normally, these materials can be plastically deformed at some relatively low temperature, and upon exposure to some higher temperature return to their shape prior to the deformation. Materials which show shape memory only upon heating are referred to as having a one-way shape memory. Some materials also undergo a change in shape upon recooling. These materials have a two-way shape memory. Although a relatively wide variety of alloys are known to show the shape memory effect, only those which can recover substantial quantities of strain or which generate substantial force upon changing shape are of commercial interest. To date, this has been the nickel-titanium alloys and copper-base alloys such as copper-zinc-aluminum, and copper-aluminum-nickel. A shape memory alloy can be further defined as one which yields a thermo-elastic martensite. In this case, the alloy undergoes a martensitic transformation of a type which allows the alloy to be deformed by a twinning mechanism below the transformation temperature. The deformation is then reversed when the twinned structure reverts upon heating to the parent phase.
Shape memory effect (SME) – It refers to the ability of certain materials, particularly shape memory alloys (SMAs), to recover their original shape after being deformed, frequently because of the temperature changes or stress. This ‘memory’ of their original form allows them to return to their intended shape after being bent or distorted.
Shape replication process – It is a mass-conserving process in which the part replicates the shape information stored in the die or mould by being forced to assume the shape of the surface of the tool cavity.
Shape resolution – It is an electron image which shows shape resolution when a polygon can be recognized as such in the image. Roughly, the particle diameter, which is defined as the diameter of a circle of the same area as the particle, is to exceed the resolution by a factor equal to the number of sides on the polygon.
Shaping – It means producing flat surfaces using single-point tools. The work is held in a vise or fixture or is clamped directly to the table. The ram supporting the tool is reciprocated in a linear motion past the work.
Shared governance – It is a collaborative, goal-setting, and problem-solving process built on trust and communication where different stakeholders share responsibility for setting and achieving shared outcomes.
Shared outcome – It consists of outcomes which is developed and defined using a collaborative approach. Shared governance, accountability, responsibility, and stewardship start with an agreement on what the parties, representing different interests, want to see as the end result. Development of shared outcomes requires decisions on who needs to be involved and the best process to use.
Shared responsibility – It is the recognition that resource and environmental management is not solely the responsibility of government. Good resource and environmental management is based on cooperation, collaboration, and partnerships among parties which have an interest in achieving resource and environmental outcomes. Shared responsibility recognizes the role which the different parties can play in resource and environmental management, but understands that management is to be carried out within clear governance and accountability frameworks.
Shark’s teeth – It is a striation consisting of a daggerlike step fracture starting at the scored edge and extending to or nearly to the compression edge.
Sharp edges – These typically refer to the thin, cutting edge of a physical object, like a knife or a tool, that allows it to cut through materials easily. It can also describe a distinct, abrupt line or boundary between two things. In a more figurative sense, sharp edges can also describe something which is forceful, direct, or even caustic in its delivery.
Sharp notch – It is a precise, pointed indentation or cut with a very small or near-zero radius at its tip, which creates a stress singularity and high stress concentrations in a material, typically used in engineering tests to assess material fracture toughness and fatigue. Unlike a blunt notch, which has a rounded tip, a sharp notch is characterized by its extreme sharpness, allowing for more accurate study of failure mechanisms under controlled conditions.
Sharp-notch strength – It is the notch tensile strength measured using samples with very small notch root radii (approaching the limit for machining capability). Values of sharp-notch strength usually depend on notch root radius.
Sharp sand – It is the sand free from binders, i.e., new, clean sand of angular shape. The term does not refer to grain shape.
Shate – It is a term used for rolled material where the thickness lies between that of cold rolled sheet and hot rolled plate, typically 4 millimeters to 10 millimeters. The finish can be hot or cold rolled.
Shatter crack – It is a short, discontinuous internal crack in ferrous metals attributed to stresses produced by localized transformation and hydrogen-solubility effects during cooling after hot working. In fracture surfaces. Shatter cracks appear as bright, silvery areas with a coarse texture. In deep acid-etched
transverse sections, they appear as discontinuities which are normally in the midway to centre location of the section. It is also termed hairline cracks or flakes.
Shaving – As a finishing operation, it is the accurate removal of a thin layer of a work surface by straight-line motion between a cutter and the surface. It also consists of trimming parts such as stampings, forgings, and tubes to remove uneven sheared edges or to improve accuracy.
Shavings – These are pieces of metal, wood, or plastic that are the debris or waste resulting from machining, wood-working, or similar subtractive (material-removing) manufacturing processes.
Shaw (Osborn-Shaw) process – It is a precision casting process which employs permanent patterns and fine-grain slurry for making moulds. Unlike monolithic investment moulds, which are similar in composition, ceramic moulds consist of a cope and a drag or, if the casting shape permits, a drag only.
SHE – It is abbreviation for safety, health, and environment.
Shear – It is an action or stress resulting from applied forces which causes or tends to cause two contiguous parts of the same body to slide relative to each other in a direction parallel to their plane of contact. It is also a machine or tool for cutting metal and other material by the closing motion of two sharp, closely adjoining edges, e.g., squaring shear and circular shear. It also means an inclination between two cutting edges, such as between two straight knife blades or between the punch cutting edge and the die cutting edge, so that a reduced area gets cut each time. This lessens the necessary force, but increases the needed length of the working stroke. This method is referred to as angular shear. Shear also means the act of cutting by shearing dies or blades, as in shearing lines. In composites, in inter-laminar shear, the plane of contact is composed mainly of resin. In geology, shear or shearing is the deformation of rocks by lateral movement along innumerable parallel planes, normally resulting from pressure and producing such metamorphic structures as cleavage and schistosity. In crushing, shear consists of a trimming or cleaving action rather than the rubbing action associated with attrition. Shear is normally combined with other methods, e.g., single roll crushers use shear together with impact and compression. Shear crushing is normally called for under the conditions when material is somewhat friable or when a relatively coarse product is needed. It is normally employed for primary crushing with a reduction ratio of 6 to 1.
Shear angle – It is the angle which the shear plane, in metal cutting, makes with the work surface.
Shear assisted processing and extrusion (ShAPE) – It is a solid phase processing (SPP) technique, meaning it consolidates and shapes materials without melting them. It is a metal forming technique which uses simultaneous rotational and linear forces to extrude materials, like metal alloys, through a die. This process, which combines shear and extrusion, enables the creation of high-strength structures from different feedstocks, including powders, flakes, and billets, without the need for preheating or melting. It offers advantages like energy efficiency, improved material properties (strength, ductility, and fatigue life), and the ability to process materials which are difficult to extrude conventionally.
Shear bands – These are the bands of very high shear strain which are observed during rolling of sheet metal. During rolling, these form at around 35-degree to the rolling plane, parallel to the transverse direction. They are independent of grain orientation and at high strain rates traverse the entire thickness of the rolled sheet. Shear bands are also highly localized deformation zones in metals which are observed at very high strain rates, such as those produced by high velocity (100 meters per second to 3,600 meters per second) projectile impacts or explosive rupture.
Shear behaviour – It refers to the response of a material or object when a force is applied over a given distance, frequently resulting in deformation or movement which homogenizes and heats the raw ingredients.
Shear blades – These are cutting tools, usually made of hardened steel, designed to cut materials by applying a force to a fixed cutting edge, like a scissor. They are used in various machines and processes, including shearing machines, hydraulic shears, and even hand-held shears.
Shear compliance – It is the reciprocal of shear modulus. It is also a term used in the evaluation of stiffness and deflection.
Shear edge – It is the cut-off edge of the mould.
Shear encoder – It is the incremental encoder connected to the shear motor and is used to detect the shear blade position.
Shear failure – It occurs when a material or structure breaks or deforms considerably under a force acting parallel to its surface (shear force), causing layers to slide past each other. This frequently results in diagonal cracks, especially in reinforced concrete, and can manifest in several ways, such as punching shear in concrete foundations, shear fracture in metals under dynamic loads, or shearing of soil layers.
Shear fracture – It is a mode of fracture in crystalline materials resulting from translation along slip planes which are preferentially oriented in the direction of the shearing stress.
Shear hackle – It is a hackle generated by interaction of a shear component with the principal tension under which the crack is running.
Shearing – It is a cutting process, frequently used in metalworking, where a material is separated along a designated line by applying a force, typically using a machine with sharp blades. Shearing cuts stock without the formation of chips or the use of burning or melting of the material. In scrap processing, shearing means the cutting and pressing of thicker scrap steel. Shearing takes place in big, guillotine-like scrap shears. Steel beams and miscellaneous scrap are cut into 600 millimeters or 800 millimeters pieces. Shearing increases the bulk density of the scrap, making it easier to handle and portion out. A hydraulic guillotine shear slices heavy pieces of steel including ‘I’ and ‘H’ beams, ship plate, pipe, and railroad car sides. Shears vary in size from 300 tons to more than 2,000 tons of head force.
Shearing angle – It is also called shear angle. It describes the angle of a deforming material’s shear plane, which can be interpreted in two main contexts namely (i) shearing strain, as the relative displacement between opposite faces of an object due to a tangential force, and (ii) in metal cutting, as the angle between the tool’s path and the shear plane where the material is cut and chips are formed. A smaller shearing angle can lead to higher machining forces, increased tool wear, and poorer surface finish, while an optimal angle minimizes material deformation and resistance, improving productivity.
Shearing defect – It occurs when a longitudinal strip of the base metal is torn off the wire rod during rolling. The strip is frequently reattached as rolling continues, although not necessarily to the same rod. Shearing can refer to either the discontinuity caused by detachment or subsequent reattachment. Shearing is visually detected. Microscopic examination sometimes indicates an overheated condition between grains. Excessive rubbing of steel as it rolls through the mill causes overheating, shearing material which is later picked up from mill components on the same or another rod. Mill adjustments can reduce sources of frictional heating. Improved guiding, pass design, and section control can reduce incidents of shearing.
Shearing forces – These forces are unaligned forces acting on one part of a body in a specific direction, and another part of the body in the opposite direction. When the forces are collinear (aligned with each other), they are called tension forces or compression forces. Shear force can also be defined in terms of planes, i.e., If a plane is passed through a body, a force acting along this plane is called a shear force or shearing force.
Shearing strain – It is the angular deformation of a material caused by a shear force, defined as the ratio of the lateral displacement of one layer relative to another to the original distance between those layers, or as the tangent of the angle of shear. It measures the change in shape, not volume, and is an important concept for designing structures and components subjected to forces like torsion, cutting, or sliding, as found in beams, shafts, and gears.
Shearing stress – It is a force per unit area that acts parallel to a material’s surface, causing its layers to slide past each other. It is calculated by dividing the shear force by the area over which it acts. This stress is critical for understanding how materials deform under conditions like cutting with scissors.
Shear ledges – These are lines on a fracture surface which radiate from the fracture origin and are visible to the unaided eye or at low magnification. Radial marks result from the intersection and connection of brittle fractures propagating at different levels. These are also known as radial marks.
Shear load – It is a force which acts parallel to a surface, causing different parts of a material to slide relative to each other, rather than pulling (tension) or pushing (compression) directly on the entire component. This type of load induces shear stress, which is the force per unit area that resists this sliding motion within the material. Examples include using scissors to cut metal strip, the torsional force on a shaft, or the forces experienced by tires as they turn.
Shear lip – It is a narrow, slanting ridge along the edge of a fracture surface. The term sometimes also denotes a narrow, frequently crescent-shaped, fibrous region at the edge of a fracture which is otherwise of the cleavage type, even though this fibrous region is in the same plane as the rest of the fracture surface.
Shear modulus (G) – It is the ratio of shear stress to the corresponding shear strain for shear stresses below the proportional limit of the material. Values of shear modulus are normally determined by torsion testing. It is also known as modulus of rigidity.
Shear pin – It is a mechanical detail designed to allow a specific outcome to occur once a pre-determined force is applied. It can either function as a safeguard designed to break to protect other parts, or as a conditional operator which does not allow a mechanical device to operate until the correct force is applied. In conveyor system, shear pin is a purposefully designed pin which is meant to fracture under excessive loads, serving as a protective measure for conveyor components. Regular inspections are imperative to verify the presence and structural integrity of shear pins, assuring ongoing safeguarding.
Shear plane – It is a confined zone along which shear takes place in metal cutting. It extends from the cutting edge to the work surface.
Shear proximity switch – It is the sensor which is used to reset the shear position at the moment of the cut.
Shears – Shears are used to cut thin sheet, plates, billets, rounds, squares, sections, beams, and bars etc. Depending on the application, shears typically employ a fixed lower blade and a moving upper blade to perform the cutting action. The type of shears to be used is determined by many factors, including the material length that it can process and the thickness and type of material which it has to cut. Hot shears are used in the rolling mills for front and tail end cropping, cobble cutting and dividing. Crank, rotary and combined shears at different speed ranges are normally employed to optimize front and tail end cropping, cobble cutting and dividing. Depending on the mill requirements the shears can be used along with pinch rolls and auxiliary chopping shears. Several types of shears can be employed by a mill to cut the rolled product as it rolls, as it exits the finishing stand, and cold shearing before stacking or bundling. Depending on the product shape and material grade, shears can be used to cut the front of the bar as it proceeds through the mill. These are typically flying shears. The blades of this shear move parallel to the bar during the cut. In multi-strand rolling of rebar, there is a requirement of a shear in the mill which provides a clean front end of the bar to avoid cobbles at the slitting stand. Certain grades, such as leaded steels, require front end trimming to prevent cracks at the front end from splitting open and the bar wrapping the rolls. A drum type shear is generally used for product with a simple shape such as flats or rounds. The blades are mounted on a rotating cylinder (or drum) and are set at a ‘lead’ speed to minimize the ‘kinking’ of the bar.
Shear stability – It is the ability of a lubricant to withstand shearing without degradation.
Shear strain – It is the tangent of the angular change, caused by a force between two lines originally perpendicular to each other through a point in a body. It is also called angular strain.
Shear strength – It is the strength of a material or component against the type of yield or structural failure when the material or component fails in shear. A shear load is a force which tends to produce a sliding failure on a material along a plane that is parallel to the direction of the force. When a paper is cut with scissors, the paper fails in shear. In structural and mechanical engineering, the shear strength of a component is important for designing the dimensions and materials to be used for the manufacture or construction of the component (e.g., beams, plates, or bolts). In a reinforced concrete beam, the main purpose of reinforcing bar (rebar) stirrups is to increase the shear strength. In case of aluminum alloys, as a very rough guide, the maximum shear strength is around 60 % to 65 % of the ultimate tensile strength and the yield strength in shear is 50 % to 55 % of the 0.2 % proof stress. In case of concrete, it is extremely difficult in laboratory testing to get pure shear failures unaffected by other stresses. As a result, the tests of concrete shearing strengths through the years have yielded values all the way from one-third to four-fifths of the ultimate compressive strengths
Shear stress – It is the stress component which is tangential to the plane on which the forces act. It is also a stress which exists when parallel planes in metal crystals slide across each other. It is the component of stress coplanar with a material cross section. It arises from the shear force, the component of force vector parallel to the material cross section. Normal stress, on the other hand, arises from the force vector component perpendicular to the material cross section on which it acts.
Shear stud – It is a metal pin with a head, welded to the top flange of a steel beam, and designed to transfer shear forces between the steel element and a concrete slab in composite structures. These studs enable composite action by resisting horizontal shear stress and preventing the separation of steel beams and concrete slabs, hence improving the overall strength and stiffness of structures like bridges, tall buildings, and composite floors.
Shear test – It is a test in which the test piece is progressively loaded to fracture in shear to measure its shear strength.
Shear thickening – It is an increase in viscosity with an increase in shear stress or time.
Shear thinning -It is a decrease in viscosity with an increase in shear stress or time. The decrease in viscosity can be temporary or permanent. The latter happens when the shear stress is sufficiently large to rupture a chemical bond, so that the sheared liquid has a lower viscosity than it had prior to shearing.
Shear wave birefringence – It is also known as shear wave splitting or seismic birefringence. It is a phenomenon where a single polarized shear wave entering an anisotropic-medium splits into two polarized shear waves with different velocities. This splitting is caused by the material’s anisotropy, which can be due to cracks, fractures, or crystal alignment within the medium.
Shear yield strength – It is the average shear resistance over all orientations of slip planes in a poly-crystal, given by the relationship k = s y / 2, where ‘s y’ is the tensile yield strength.
Shear zone – It is a zone in which shearing has occurred on a large scale.
Sheath – It is a close-fitting covering used for protection, frequently applied to blades like knives and swords, but also encompassing various other objects and even biological structures. In the context of protection, a sheath acts as a case or protective layer, ensuring the object is safe from damage or injury. In case of a cable, sheath is the outermost protective covering or jacket on a cable, designed to safeguard the internal components and ensure the cable’s structural integrity. It acts as a barrier against environmental factors and mechanical damage.
Sheathing – It refers to the protective outer covering or jacket which surrounds an electrical cable. This sheath protects the cable’s inner conductors and insulation from physical damage, environmental factors like moisture and ultra-violet (UV) radiation, and chemical exposure.
Sheath voltage – It refers to the induced electrical potential in the metallic sheaths of underground cables and overhead lines, resulting from electro-magnetic coupling effects, particularly when cables are in close proximity to each other.
Sheave – It is a meticulously grooved pulley wheel which is specifically crafted for transporting a v-belt. Consistent checks are crucial to validate the stability, alignment, and overall efficacy of sheaves in facilitating smooth belt movement.
Sheave wheel – It is a large, grooved wheel in the top of a head-frame over which the hoisting rope passes.
Sheds – Several materials which need to be stored under a cover for one reason or other, but are difficult to be stored in a bin or silo, are generally stored in a shed. Sheds can be up to 100 meters in width and several hundred meters in length. Sheds are covered at top by corrugated GI (galvanized iron) sheets or corrugated asbestos sheets supported on full width strusses. Materials are normally brought in by belt conveyor and distributed in the shed by a distributing conveyor with self-propelled tripper or by a shuttle conveyor. Discharge is normally through reclaiming conveyors working below floor levels. Equipments like bulldozers, power hoe, or a drag scraper are used for moving materials towards feeding pockets for the reclaiming conveyors. Sheds are used for short to long duration storage of different materials.
Sheet – It is a flat-rolled metal product of some maximum thickness and minimum width arbitrarily dependent on the type of metal. It has a width-to-thickness ratio higher than around 50. Normally, such flat products under 6.5 millimeters thick are called sheets, and those 6.5 millimeters thick and above are called plates.
Sheet, alclad – It is composite sheet composed of an aluminum alloy core having on both surfaces (if one side only, alclad one-side sheet) a metallurgically bonded aluminum or aluminum alloy coating which is anodic to the core, hence electrolytically protecting the core against corrosion.
Sheet, anodizing – It is the sheet with metallurgical characteristics and surface quality suitable for the development of protective and decorative films by anodic oxidation processes.
Sheet, clad – It is composite sheet having on both surfaces (if on one side only, clad one-side sheet) a metallurgically bonded metal coating, the composition of which may or may not be the same as that of the core.
Sheet, coiled – It is sheet in coils with slit edges.
Sheet, coiled circles – It means circles cut from coiled sheet.
Sheet, coiled cut to length – It means sheet cut to specified length from coils and which has a lesser degree of flatness than flat sheet.
Sheet, flat – It means sheet with sheared, slit, or sawed edges, which has been flattened or levelled.
Sheet, flat circles – It means circles cut from flat sheet.
Sheet formability in steels – It refers to the ability of a steel sheet to be shaped into a desired form without failure, such as cracking or necking. It essentially describes how easily and reliably a steel sheet can be deformed plastically during different forming processes.
Sheet forming – It is the plastic deformation of a piece of sheet metal by tensile loads into a three-dimensional shape, frequently without considerable changes in sheet thickness or surface characteristics.
Sheet forming process – It is a manufacturing method which shapes thin metal sheets by applying forces, such as tension and compression, to cause plastic deformation without removing material. This process utilizes specialized tools and dies to transform a flat metal sheet into a desired geometric shape, which is crucial for creating a wide range of parts for industries like automotive. Common techniques include bending, stretching, and drawing, each with unique applications and requirements, such as considering the material’s plasticity and avoiding defects like thinning or wrinkling.
Sheet lifters – They use two claws to grab a load of sheet metal or wood by wrapping around the edges. A lip on the lower portion of the claws prevents the sheet from falling out of the lifter.
Sheet metal – It is a thin, flat piece of metal which can be formed into several shapes through processes such as bending, roll forming, spinning, and stretching, which frequently involve the application of force and the use of dies and tools.
Sheet metal fabrication – It is the manufacturing process involving the formation of thin-walled structural elements, such as plates, panels, and shells, which frequently experience buckling distortions during fusion welding. This process encompasses several techniques and methods aimed at controlling welding distortions and producing defect-free products.
Sheet metal forming – It is a manufacturing process which reshapes metal sheets into desired three-dimensional parts without cutting or significantly reducing the material’s mass. It involves applying forces, like tension and compression, to plastically deform the metal into the final shape. Common forming processes include bending, drawing, and stretching.
Sheet metal guard – It is a defensive enclosure fashioned from sheet metal, dedicated to shielding conveyor components from external influences. Rigorous and systematic checks are fundamental to confirm the steadfastness, alignment, and overall efficacy of sheet metal guards in preserving the integrity of conveyor elements.
Sheet, mill finish (MF) – It means sheet having a non-uniform finish which can vary from sheet to sheet and within a sheet and may not be entirely free from stains or oil.
Sheet moulding compound (SMC) – It is composite of fibres, normally a polyester resin, and pigments, fillers, and other additives which have been compounded and processed into sheet form to facilitate handling in the molding operation. It is a compression moulding material consisting of glass fibres in a thickened polyester resin, possibly modified with liquid nitrile polymers for increased fracture resistance.
Sheet, one-side bright mill finish (1SBMF) – It is the sheet having a moderate degree of brightness on one side and a mill finish on the other.
Sheet, painted – It is the sheet, one or both sides of which has a factory-applied paint coating of controlled thickness.
Sheet separation (resistance welding) – It is the gap surrounding the weld between faying surfaces, after the joint has been welded in spot, seam, or projection welding.
Sheet, standard one-side bright finish (S1SBF) – It is the sheet having a uniform bright finish on one side and a mill finish on the other.
Sheet, standard two sides bright finish (S2SBF) – It is the sheet having a uniform bright finish on both sides.
Sheet stock – It is the semi-finished rolled product of rectangular cross section in coiled form suitable for further rolling. Examples are foil stock and reroll stock.
Shelf– It is a flat, horizontal plane used for items which are displayed or stored in store. It is raised off the floor and frequently anchored to a wall, supported on its shorter length sides by brackets, or otherwise anchored to cabinetry by brackets, dowels, screws, or nails.
Shelf aging – It is the natural deterioration of rubber articles kept in storage or ‘on the shelf’ under normal atmospheric conditions. This slow deterioration is mainly because of oxygen and ozone attack.
Shelf energy – In the Charpy impact test, shelf energy is the upper (plateau) value of energy absorbed at a temperature well above the ductile-to-brittle transition temperature.
Shelf life – It is the length of time a material, substance, product, or reagent can be stored under specified environmental conditions and continue to meet all applicable specification requirements and / or remain suitable for its intended function. It is the length of time which a commodity can be stored without becoming unfit for use, consumption, or sale. It is also an expression describing the time an unvulcanized rubber stock can be stored without losing any of its processing or curing properties.
Shelf roughness – It is the roughness on upward-facing surfaces where undissolved solids have settled on parts during a plating operation.
Shelf storage life – It is the period of time prior to use during which a product retains its intended performance capability. Important consideration for (uncured) splicing material. It is normally a couple of months under proper storage conditions.
Shell – It is a hollow structure or vessel. It is the cylindrical portion of a pressure vessel. It is also an article formed by deep drawing. Shell is the metal sleeve remaining when a billet is extruded with a dummy block of somewhat smaller diameter. In shell moulding, it is a hard layer of sand and thermosetting plastic or resin formed over a pattern and used as the mould wall. Shell is also a tubular casting which is used in making seamless drawn tube. Shell is also a pierced forging. In case of blast furnace, she is covered with a shell of steel plate which is internally lined with refractories and has stave coolers for its cooling.
Shell and tube heat exchangers – These are similar in construction to convective recuperators, but are liquid to liquid heat exchangers. Shell and tube heat exchanger is normally used, when the medium containing waste heat is a liquid or a vapour which heats another liquid. This is because both paths must be sealed to contain the pressures of their respective fluids. The shell contains the tube bundle, and usually internal baffles, to direct the fluid in the shell over the tubes in multiple passes. Baffles are normally installed parallel to the axis of the shell, causing shell-side flow along the length of the shell. The shell is inherently weaker than the tube, so that the higher-pressure fluid is circulated in the tubes while the lower pressure fluid flows through the shell. When a vapour contains the waste heat, it usually condenses, giving up its latent heat to the liquid being heated. In this application, the vapour is almost invariably contained within the shell. If the reverse is attempted, the condensation of vapours within small diameter parallel tubes causes flow instabilities. Tube and shell heat exchangers are available in a wide range of standard sizes with several combinations of materials for the tubes and shells.
Shell Claus off-gas treating (SCOT) process – It is a tail gas treatment technology which improves sulphur recovery efficiency in a sulphur recovery unit (SRU) by converting remaining sulphur compounds in the off-gas to hydrogen sulphide (H2S), which is then recycled back to the sulphur recovery unit. This process is widely used and highly effective in achieving high sulphur recovery levels. The basic process consists of heating and reducing all sulphur species to hydrogen sulphide, cooling and quenching, and absorbing the hydrogen sulphide in an amine solution then recycling it back to the front of the Claus unit.
Shell coal gasification process (SCGP) – It refers to a method developed by Shell for the partial oxidation of coal to produce synthetic gas, primarily for electricity generation and hydrogen production.
Shell core – It is a shell-moulded sand core.
Shell electrons – These refer to the electrons which occupy the atomic shells surrounding the nucleus, which are labeled by principal quantum numbers. The maximum number of shell electrons in a given shell is determined by two times square of ‘n’, where ‘n’ is the principal quantum number.
Shell entrained flow gasifier – It is a type of gasifier which uses a high-temperature, turbulent, and pressurized environment to convert pulverized coal into syngas (synthesis gas). It is characterized by high temperatures, short residence times, and a high degree of fuel conversion. The Shell gasifier is a dry-feed, pressurized, entrained-flow slagging gasifier that can operate on a wide variety of feedstocks.
Shell hardening – It is a surface-hardening process in which a suitable steel work-piece, when heated through and quench hardened, develops a martensite layer or shell which closely follows the contour of the piece and surrounds a core of essentially pearlitic transformation product. This result is accomplished by a proper balance among section size, steel hardenability, and severity of quench.
Shelling – It is a term which is used in railway engineering to describe an advanced phase of spalling. It is also a mechanism of deterioration of coated abrasive products in which entire abrasive grains are removed from the coating which holds the abrasive to the backing layer of the product.
Shell-mould casting – Shell-mould casting yields better surface quality and tolerances. In this process, the 2-piece pattern is made of metal (e.g. aluminum or steel), it is heated to between 175 deg C to 370 deg C, and coated with a lubricant, e.g. silicone spray. Each heated half-pattern is covered with a mixture of sand and a thermoset resin / epoxy binder. The binder glues a layer of sand to the pattern, forming a shell. The process can be repeated to get a thicker shell. The assembly is baked to cure it. The patterns are removed, and the two half-shells joined together to form the mould and liquid metal is poured into the mould. When the liquid metal is solidified, the shell is broken to get the part.
Shell moulding – It is a foundry process in which a mould is formed from thermosetting resin-bonded sand mixtures brought in contact with preheated (150 deg C to 260 deg C) metal patterns, resulting in a firm shell with a cavity corresponding to the outline of the pattern. Shell moulds are made from a mixture of sand and thermosetting resin binder.
Shell mould process – It is a process in which resin-coated sand is laid on a heated pattern, bonding it together to form a hardened shell about 10 millimeters to 20 millimeters thick. Two mating shells are glued together to make a precision mould to produce a casting with excellent dimensional accuracy and a smooth surface texture.
Shell process – It is also called shell moulding. It refers to a metal casting technique where a thin-walled mould is created by coating a heated pattern with a sand-resin mixture. This method is known for producing high-precision castings with smooth surfaces and tight tolerances. The process is particularly suitable for small to medium-sized parts with complex geometries.
Shell tooling – It is a mould or bonding fixture consisting of a contoured surface shell supported by a sub-structure to provide dimensional stability.
Shell-type transformer – It is a type of transformer characterized by its magnetic core structure, where both primary and secondary windings are placed on a central limb, with outer limbs completing the magnetic circuit. Unlike core-type transformers, where windings surround the core, shell-type transformers have the core surrounding the windings. This design leads to a shorter magnetic path and frequently results in a transformer with higher mechanical strength.
Sherwood number (Sh) – It is also called the mass transfer Nusselt number. It is a dimensionless number used in mass-transfer operation. It represents the ratio of the total mass transfer rate (convection + diffusion) to the rate of diffusive mass transport. It is defined as Sh = h /(D/L) = Total mass transfer rate /diffusion rate, Sh=hD/L=Total mass transfer rateDiffusion ratewhere ‘L’ is a characteristic length (meter), ‘D’ is mass diffusivity (square meter per second), and ‘h’ is the convective mass transfer film coefficient (meter per second).
Shewed tolerances – These are the tolerances which are non-symmetrically distributed about the design parameter.
Shewhart control chart – It is also known as a statistical process control (SPC) chart or simply a control chart. It is a graphical tool used to monitor the stability and variability of a process over time. It helps determine if a process is in a state of statistical control, meaning its variations are because of random, common causes, or if there are special causes causing deviations. Two fundamental purposes which Shewhart control charts can serve are (i) as a tool to provide a sound economic basis for making a decision at the machine regarding whether to look for trouble, adjust the process, or leave the process alone, and (ii) as a means of assisting in the identification of both improvement opportunities through the detection of sporadic and chronic faults in the process and to help provide the basis to formulate corrective and improvement actions.
Shielded cable – It is a type of cable designed to reduce electro-magnetic interference (EMI) emissions by using a conductive shield which surrounds the wires, preventing electro-magnetic interference from escaping and interfering with other devices. Effective shielding needs proper grounding techniques, which can involve the use of metal back shells and connectors.
Shielded metal arc cutting – It is a metal arc cutting process in which metals are severed by melting them with the heat of an arc between a covered metal electrode and the base metal.
Shielded metal arc welding (SMAW) – This process is normally called stick, or covered electrode, welding. It is a manual welding process whereby an arc is generated between a flux-covered consumable electrode and the work piece. The process uses the decomposition of the flux covering to generate a shielding gas and to provide fluxing elements to protect the molten weld-metal droplets and the weld pool. In the shielded metal arc welding process, the arc is initiated by momentarily touching or ‘scratching’ the electrode on the base metal. The resulting arc melts both the base metal and the tip of the welding electrode. The molten electrode metal / flux is transferred across the arc (by arc forces) to the base-metal pool, where it becomes the weld deposit covered by the protective, less-dense slag from the electrode covering. The shielded metal arc welding process is the most widely used welding process. It is the simplest, in terms of equipment requirements, but it is, perhaps, the most difficult in terms of welder training and skill-level requirements. In this process, pressure is not used, and filler metal is obtained from the electrode.
Shielded twisted pair – It consists of two wires, wrapped around each other and covered with a flexible shield conductor, intended to reject external interference.
Shielded welding electrode – It is normally used in the shielded metal arc welding (SMAW). It is a consumable electrode coated in flux which provides shielding gas to protect the weld area from atmospheric contamination. This flux also forms which protects the weld during cooling. Basically, it is a stick electrode with a flux covering which melts during welding, creating a protective atmosphere and slag layer.
Shielding – It refers to the act of protecting something from harm or external influences, frequently using a physical barrier or a method of isolation. This can involve shielding from radiation, electro-magnetic interference, heat etc. Broadly, it is the use of certain protective materials to prevent or reduce the quantity of ionizing radiation to which people and / or equipment are exposed. Shielding is a material barrier which prevents radiation or a flowing fluid from impinging on an object or a portion of an object. In an electron-optical instrument, it is the protection of the electron beam from distortion because of the extraneous electric and magnetic fields. Since the metallic column of the microscope is at ground potential, it provides electrostatic shielding. Shielding also means placing an object in an electrolytic bath so as to alter the current distribution on the cathode. A non-conductor is called a shield, while a conductor is called a robber, a thief, or a guard.
Shielding gas – It is the protective gas which is used to prevent atmospheric contamination during welding. It is also a stream of inert gas directed at the substrate during thermal spraying so as to envelop the plasma flame and substrate which is intended to provide a barrier to the atmosphere in order to minimize oxidation.
Shielding of an electric power cable – Shielding of an electric power cable is accomplished by surrounding the insulation of a single conductor or assembly of insulated conductors with a grounded, conducting medium. This confines the electric field to the inside of this shield. Two distinct types of shields are used namely metallic and a combination of non-metallic and metallic. Shielding layers which are provided for protection of the cable are (i) inner sheath, (ii) armouring, and (iii) outer sheath.
Shift – It is a casting imperfection caused by mismatch of cope and drag or of cores and moulds. Shift also typically refers to a work schedule which divides the workday into distinct periods (shifts) to ensure continuous operation or coverage, frequently involving different groups of workers taking turns.
Shift factor – It is the relative change in time needed to simulate a property at a changed temperature compared to a reference temperature, indicating time shortening for low-temperature properties and time lengthening for high-temperature properties. It describes the relationship between time and temperature in getting equivalent test results for material behaviour.
Shift force – In magnetic handling devices, it is the parallel force needed for the loosening of the attracted piece. Depending on the surface finish of the attracted piece, the force can vary between 20 % to 35 % of the holding force.
Shift in a reaction – It is frequently referred to as a shift in equilibrium. It refers to a change in the position of equilibrium when conditions like temperature, pressure, or reactant / product concentrations are altered, causing the reaction to favour either reactants or products.
Shift operation – It is a computer-based process which moves the bits within a digital word (like a register) to the left or right by a specified number of positions. These operations are fundamental to bitwise operations and are used for multiplying or dividing by powers of two, manipulating data efficiently, and for other low-level programming tasks. Common types include logical left shift, logical right shift, arithmetic right shift, and rotate right, each with specific rules for handling bits which are shifted off the ends.
Shim – It is a thin piece of material which is used between two surfaces to get a proper fit, adjustment, or alignment.
Shimmy die – It is a machine for trimming notched edges on shells. The slide is cam driven so as to get a brief dwell at the bottom of the stroke, at which time the die. It is sometimes called flat edge trimmer. It is a shimmy die which oscillates to trim the part.
Shiplap liner – Shiplap is a board with edges rabbeted so as to overlap flush from one board to the next. The purpose of shiplap is to create a tight, overlapping joint between boards, providing a durable and aesthetically pleasing surface for walls and ceilings.
Shipping – It refers to the process of preparing and sending out a shipment after it is ready for delivery. It involves activities like packaging, labelling, and handing over the goods to a carrier. Shipment, on the other hand, is the entire journey of goods from the origin to the destination, including the dispatch phase.
Shipping ton – It is also known as a freight ton or measurement ton. It is a unit used to measure the volume of cargo for shipping purposes. It is not a measure of weight but rather a way to quantify the space occupied by goods when calculating shipping costs. In essence, it represents the space a ‘ton’ of cargo takes up, which can be more relevant than weight for some shipments.
Shitsuke (Self-discipline) – This means the employees are to follow a way of life and bring about self-discipline. This includes wearing badges, following of work procedures, punctuality, and dedication to the organization etc.
Shock – Shock refers to a sudden and severe jolt or impact to a system, frequently causing significant disruption. It is characterized by rapid acceleration and short duration. Engineers frequently study and test for shock loads in different applications, such as ensuring the durability of products during transportation or use.
Shock absorber – It is also called damper. It is a mechanical or hydraulic device designed to absorb and damp shock impulses. It does this by converting the kinetic energy of the shock into another form of energy (typically heat) which is then dissipated. Majority of shock absorbers are a form of dashpot (a damper which resists motion through viscous friction). Pneumatic and hydraulic shock absorbers are used in conjunction with cushions and springs.
Shockley dislocations – These can be a type of dislocation formed in a material which interacts with Frank dislocations at the twin interface, where they can become locked and subsequently unlock during deformation processes.
Shockley partial dislocation – It is a type of partial dislocation associated with slip in face-centered cubic metals, characterized by a Burgers vector shorter than that of a perfect dislocation and linked to the formation of stacking faults within a crystal.
Shock load – It is the sudden application of an external force which results in a very rapid buildup of stress, e.g., piston loading in internal combustion engines.
Shock loads – These are sudden, transient forces which are extremely high in magnitude and short in duration, typically caused by impacts or sudden changes in motion, such as collisions, drops, or explosive events. These loads can cause severe deformation, breakage, or damage to materials and structures, and their effects are frequently analyzed using a ‘shock response spectrum’ (SRS) in engineering.
Shock pressure – It is the pressure exerted by a material during a shock event, which is initially higher than the theoretical pressure because of the material’s response and subsequently stabilizes into a pressure plateau. It is influenced by factors such as bulk viscosity and varies with impact velocity, with porous materials showing lower shock pressures compared to pure materials.
Shock resistance – It refers to a material’s or device’s ability to withstand sudden impacts and forces without damage or malfunctioning general, it signifies a structure or component’s resilience to physical shocks.
Shock wave – It is a type of propagating disturbance which moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a medium, but is characterized by an abrupt, nearly discontinuous, change in pressure, temperature, and density of the medium.
Shock wave testing of ductile materials – It involves subjecting a material to a sudden, high-pressure disturbance (a shock wave) to study its dynamic response and properties under extreme conditions. This testing helps understand how materials behave under rapid loading and high strain rates, which are crucial for applications like impact resistance, penetration, and structural integrity.
Shoe – It is a metal block which is used in a variety of bending operations to form or support the part being processed. It is an anvil cap or sow block. It is also a device for gathering filaments into a strand, in glass fibre forming.
Shoot – It is a concentration of mineral values. It is that part of a vein or zone carrying values of ore grade.
Shop drawing – Shop drawing can be prepared by contractors, sub-contractors, suppliers, manufacturers, or fabricators. The shop drawing normally relates to pre-fabricated components, showing how they are to be manufactured or installed. It takes design intent drawings and specifications prepared by the project design team and develop them to show in detail how the component is actually to be manufactured, fabricated, assembled, or installed. Shop drawings are also a sort of construction guide which personifies how the object is to be installed, fitted, or manufactured. Shop ensure compliance with the original design and specifications of the object. drawings
Shop floor management – It is the process of overseeing and improving operations on the manufacturing shop floor, utilizing frameworks and analytical methods to improve efficiency and optimize production systems within the context of an information field.
Shore – It is the edge of a body of water and includes the land adjacent to a body of water which has been covered so long by water as to wrest it from vegetation or as to mark a distinct character on the vegetation where it extends into the water or on the soil itself.
Shore-based steel plant – It is an integrated steel facility located near a coastline, allowing for the cost-effective import of raw materials like iron ore and coal by sea and the export of finished steel products. These plants leverage their port location for efficient logistics and also benefit from access to water for cooling and other operational processes.
Shore hardness – It is a measure of the resistance of material to indentation by 3 spring-loaded indenters. The higher is the number, the greater is the resistance. The Durometer scale was defined by Albert Ferdinand Shore, who developed a device to measure Shore hardness in the 1920s. The term Durometer is often used to refer to the measurement as well as the instrument itself. Durometer is typically used as a measure of hardness in polymers, elastomers, and rubbers.
Shore hardness test – It is same as Scleroscope hardness test. It is a dynamic indentation hardness test using a calibrated instrument which drops a diamond-tipped hammer from a fixed height onto the surface of the material being tested. The height of rebound of the hammer is a measure of the hardness of the material.
Shore Scleroscope – It measures hardness in terms of material elasticity. A diamond-tipped hammer (size of 40 grains, 2.59 grams) is used to strike the testing surface from a known height (254 millimeters). The rebound of the hammer is measured. The harder the material, the higher the rebound. The hammer rebound is also affected by other factors, such as the smoothness of the test surface, and the mass, depth, and contour of the sample.
Short beam shear (SBS) – It is a flexural test of a sample having a low-test span-to-thickness ratio (e.g., 4:1), such that failure is mainly in shear. It is a three-point flexure test used to measure the shear strength of composite materials. It’s a quick and relatively inexpensive method for assessing the interlaminar shear strength, or the ability of the material to resist shear forces between layers.
Short centre conveyor – It is a conveyor which is characterized by a limited span between idlers. It is frequently used in scenarios with confined spatial constraints. Regular assessments are imperative to secure optimal alignment, sustain idler health, and uphold the overall performance of the conveyor.
Short circuit – It is a path in a circuit which has negligible resistance. It is frequently un-intended, a fault.
Short circuit conditions – It refer to situations where electrical current bypasses its intended path, frequently because of the accidental contact or damaged insulation, leading to immediate and potentially severe damage in the electrical system.
Short circuit protection – It is a mechanism which automatically limits current to prevent excessive power dissipation when a short circuit occurs, frequently utilizing voltage monitoring circuits to reduce current and safeguard the system.
Short circuit rating – It is the maximum current which a conductor can safely carry during a fault condition, typically assessed over a one-second duration, without exceeding specified temperature limits that could damage the conductor or its insulation.
Short-circuit test – It is a test of machines or apparatus where the load terminals are directly connected. It is normally done at reduced power to prevent damage, but destructive short circuit testing can be carried out on circuit protective devices.
Short circuiting transfer (arc welding) – It is metal transfer in which molten metal from a consumable electrode is deposited during repeated short circuits. In consumable electrode arc welding, it is a type of metal transfer which is similar to globular transfer, but in which the drops are so large that the arc is short circuited momentarily during the transfer of each drop to the weld pool.
Short gate – It is a gate valve wherein the seat rings contact the gate only in the closed position. Such valves are not through-conduit, as the gate is completely withdrawn from the flow area in the open position.
Short message service (SMS) – It is a cellular network facility which allows users to send and receive text messages of up to 160 alpha-numeric characters on their handset.
Shortness – It is a form of brittleness in metal. It is designated as cold shortness or hot shortness to indicate the temperature range in which the brittleness occurs.
Short laser pulses – These are laser emissions with pulse widths on the order of nano-seconds, characterized by high peak power that significantly exceeds average power, making them suitable for precise micro-machining applications on several materials.
Short shot – It is the injection of insufficient material to fill the mould.
Short-term etching – In metallographic preparation of samples, it is the etching times of seconds to a few minutes.
Short time load – It is also known as short time duty or short time operation. It indicates an operating mode of increased performance but for a shorter length of time. It is also normally referred to the maximum load (the performance) at which and the related maximum length of time a device can be operated without to failure.
Short ton – It is also known as a net ton or American ton. It is a unit of weight equal to 2,000 pounds. This is in contrast to the long ton, which is 2,240 pounds, and the metric ton (or tonne), which is 1,000 kilo-grams (around 2,204.6 pounds).
Short transverse – Literally, ‘across’, It is normally signifying a direction or plane perpendicular to the direction of working. In rolled plate or sheet, the direction across the width is frequently called long transverse, and the direction through the thickness, short transverse. It is also known as transverse direction.
Short transverse direction – It refers to the material direction which is perpendicular to both the longitudinal and long transverse directions, frequently corresponding to the thickness of a material like a sheet or plate. In other words, it is the direction which is perpendicular to the main direction of extension or rolling. It is the minor axis at right angles to the major, longitudinal axis.
Short wave-length – It refers to electro-magnetic radiation which has a shorter distance between successive peaks compared to longer wave-lengths, resulting in higher energy content. In the context of sunlight, shorter wavelengths include ultraviolet (UV) radiation, which is further classified into UV-A, UV-B, and UV-C categories.
Short wave-length X-rays – These are defined as electro-magnetic radiation with wave-lengths ranging from a few angstroms to 0.1 angstroms, corresponding to photon energies between 1 keV to 120 keV, making them suitable for probing the structural arrangement of atoms and molecules in different materials.
Short-wave (SW) radiation – It is thermal radiation in the optical spectrum, including visible (VIS), near-ultraviolet (UV), and near-infrared (NIR) spectra. There is no standard cut-off for the near-infrared range; therefore, the shortwave radiation range is also variously defined. It can be broadly defined to include all radiation with a wavelength of 0.1 micro-meters and 5 micrometers or narrowly defined so as to include only radiation between 0.2 micro-meters and 3 micrometers. There is little radiation flux (in terms of watts per square meters) to the earth’s surface below 0.2 micro-meters or above 3 micro-meters, although photon flux remains significant as far as 6 micro-meters, compared to shorter wave-length fluxes. UV-C radiation spans from 0.1 micro-meters to .28 micro-meters, UV-B from 0.28 micro-meters to 0.315 micro-meters, UV-A from 0.315 micro-meters to 0.4 micro-meters, the visible spectrum from 0.4 micro-meters to 0.7 micro-meters, and near-infrared arguably from 0.7 micro-meters to 5 micro-meters, beyond which the infrared is thermal. Short-wave radiation is distinguished from long-wave radiation. Downward short-wave radiation is related to solar irradiance and is sensitive to solar zenith angle and cloud cover.
Shot – It is a small, spherical particles of metal. It also means the injection of molten metal into a die casting die. The metal is injected so quickly that it can be compared to the shooting of a gun.
Shot-blasting – It is the abrasive blasting of steel with metal shot. It is normally done to remove deposits or mill scale more rapidly or more effectively than can be done by sand-blasting or chemical cleaning.
Shot blasting process – It is also sometimes called abrasive blasting process. The process is used for descaling of steel. It is a surface treatment process in which cleaning of the surface of steel is carried out by forceful direction of an abrasive media applied either in dry state or suspended in a liquid medium, against the surface of the steel. The abrasive particles are concentrated at high speed (50 meters per second to 110 meter per second) in a controlled manner at the steel material. The abrasive impact of the abrasive particles removes the scale and other surface contaminants.
Shot capacity – It is the maximum weight of material which an injection machine can provide from one forward motion of the ram, screw, or plunger.
Shot content – In refractories, it is the percentage of non-fibrous particles that would be retained on a 75 millimeters nominal aperture sieve complying with the requirements given in ISO 565.
Shotcreting – It is an installation technique using a pump to convey tempered refractory castable to a nozzle where an admixture and air pressure are injected, spraying the castable stream onto a substrate where the castable becomes sufficiently stiff to withstand the force of gravity.
Shot impact angle – It refers to the angle between the direction of the projectile’s trajectory and the surface it impacts. This angle is crucial as it influences the outcome of the impact.
Shot peening – It is a method of cold working metals in which compressive stresses are induced in the exposed surface layers of parts by the impingement of a stream of shot, directed at the metal surface at high velocity under controlled conditions. It differs from blast cleaning in primary purpose and in the extent to which it is controlled to yield accurate and reproducible results. Although shot peening cleans the surface which is being peened, this function is incidental. The major purpose of shot peening is to increase fatigue strength. Shot for peening is normally made of iron, steel, or glass.
Shotting – It is the production of shot by pouring molten metal in finely divided streams. Solidified spherical particles are formed during descent in a tank of water.
Shoulder – It is a non-standard term for root face.
Shovel – It is a tool used for digging, lifting, and moving bulk materials, such as soil, coal, gravel, snow, sand, or ore. Majority of the shovels are hand tools consisting of a broad blade fixed to a medium-length handle. Shovel blades are normally made of sheet steel or hard plastics and are very strong.
Shredded scrap – It is a fist-sized, homogenous pieces of old automobile hulks. After cars are sent through a shredder, the recyclable steel is separated by magnets. Mini-mills consume shredded scrap in their electric arc furnace operations.
Shredders These incorporate rotating magnetic drums to extract steel from the mixture of metals and other materials. Shredders or fragmentizers can reduce old automobile hulks into fist-sized pieces using massive hammer-mills. A medium-size shredder uses 36 hammers weighing 120 kilograms each to pound auto hulks to pieces. Although the predominant raw material for the shredder is automobile hulks, ‘white goods’ (household appliances such as stoves, washers, dryers, and refrigerators) and other large items can also be shredded. Depending on its size, a shredder can process from 1,500 tons to more than 20,000 tons of steel scrap per month.
Shredding – It refers to the process of breaking down or reducing materials into smaller, more manageable pieces or fragments, frequently for recycling or processing. This process, especially in the metal recycling industry, uses machines like shredders to cut or crush scrap metal into ‘shreds’ or smaller chunks. The resulting ‘shredded scrap’ is then more easily sorted, transported, and processed further, e.g., for separation of different metal types. Shredding process produces three types of material namely (i) steel scrap, (ii) shredder residue (light fraction), and (iii) shredder residue (heavy fraction). The two residue fractions, either singularly or collectively, are frequently referred to as automotive shredder residue (ASR). ‘Shredder fluff’ is the term given to the low density or light materials, which are collected during the shredding process for cyclone air separation. Each ton of steel which is recovered produces around 300 kilograms of automotive shredder residue, comprised of plastics, rubber, glass, foam and textiles, contaminated by oil and other fluids. The steel scrap is recovered by the shredder operator using magnetic separation and used as charge for the steelmaking furnaces. The automotive shredder residue heavy fraction contains primarily aluminum, stainless steel, copper, zinc and lead.
Shredded scrap – It is normally similar to shredded clippings except that shredded scrap is likely to contain more shreddings from auto bodies, and can contain more plastics, aluminum, and other contaminants. It includes homogeneous iron and steel scrap, magnetically separated, originating from automobiles, unprepared number 1 and number 2 steel, and miscellaneous baling and sheet scrap. Average density of this category of scrap is 0.8 tons per cubic meter.
Shredded clippings – These clippings consist of shredded low carbon steel clippings or sheets. This scrap category is to have an average density of 1 ton per cubic meter.
Shredded tin cans for re-melting – This scrap category includes shredded steel cans (tin coated or tin free) and can include aluminum tops but is to be free of aluminum cans, non-ferrous metals except which is used in can construction, and non-metallics of any kind.
Shredder residue – It is also known as auto shredder residue (ASR). It is the leftover material after shredding vehicles and appliances to separate ferrous and non-ferrous metals. It mainly consists of non-metallic materials like plastics, rubber, glass, and fibres, along with some residual metals and other debris. The term ‘scrap’ in this context refers to the waste materials left over after the valuable metals have been recovered from the shredded debris.
Shrink -It is the difference in volume between liquid metal and solid metal or the void (shrink hole) left in a casting because of it.
Shrink hole – It is a cavity in a casting because of insufficient feed metal.
Shrink rule – It is the patternmaker’s rule graded to allow for metal contraction.
Shrinkage – It refers to a reduction in size or volume of a material or component, frequently because of the factors like moisture loss, cooling, or chemical reactions. In concrete, shrinkage is a contraction caused by drying or chemical changes, which can lead to cracks and other structural issues. In materials like plastics, shrinkage occurs during cooling and solidification, impacting the final dimensions of the product. In hot forging, it is the contraction of metal during cooling after hot forging. Die impressions are made oversize as per the according to precise shrinkage scales to allow the forgings to shrink to design dimensions and tolerances. In case of casting, shrinkage is the quantity of dimensional change per unit length of the casting as it solidifies in the mould or die and cools to room temperature after removal from the mould or die. There are three distinct types of casting shrinkage. Liquid shrinkage refers to the reduction in volume of liquid metal as it cools to the liquidus. Solidification shrinkage is the reduction in volume of metal from the beginning to the end of solidification. Solid shrinkage involves the reduction in volume of metal from the solidus to room temperature. In refractories, shrinkage is the decrease in dimension of a refractory material during manufacture or service. In composites, shrinkage is the relative change in dimension from the length measured on the mould when it is cold to the length of the moulded object 24 hours after it has been taken out of the mould.
Shrinkage cavity – It is a void left in cast metal as a result of solidification shrinkage. Shrinkage cavities can appear as either isolated or interconnected irregularly shaped voids. These are sub-surface discontinuities which are found in the cast materials. These cavities are caused by the lack of enough liquid metal to fill the space created by shrinkage. These are similar to pipe in an ingot. Shrinkage cavities can appear as either isolated or interconnected irregularly shaped voids.
Shrinkage, centre-line – It is the shrinkage occurring in the centre of casting sections, particularly with plate-like or bar-like contours, which solidify simultaneously from two faces and cut off feeding in the central portion.
Shrinkage cracks – These are cracks which form in metal as a result of the pulling apart of grains by contraction before complete solidification.
Shrinkage, pattern-makers – It is a linear scale or ruler, typically in milli-meters which has been lengthened by the percentage of linear shrinkage by which liquid metal contracts during solidification and cooling.
Shrinkage porosity – It consists of micro-scale inter-dendritic porosity in a casting caused by inadequate feeding during solidification. It also means macro-scale cavities in the last area to solidify, e.g., along the centre-line of an ingot.
Shrinkage process – It refers to the reduction in volume and characteristic size of sludge during the convective drying process due to the removal of water, which results in irregular forces within the sludge. This phenomenon limits the evaporation capacity of water and can lead to surface hardening and cracking of the sludge.
Shrinkage rule – It is a measuring scale with graduations expanded to compensate for the change in the dimensions of the solidified casting as it cools in the mould.
Shrinkage stoping – It is a stoping method which uses part of the broken ore as a working platform and as support for the walls of the stope.
Shrinkage stress – It is a non-standard term for residual stress.
Shrinkage void – It is a cavity type discontinuity normally formed by shrinkage during solidification.
Shrink etching – It is the precipitation on grain surfaces. Shrinkage takes place during drying which cracks the layer formed during etching. Crack orientation depends on the underlying structure.
Shrink fitting – It is a technique which joins two components by utilizing thermal expansion and contraction to create an interference fit. The outer part is heated (or the inner part is cooled) so it can slide or fit onto the other component, and once the temperature returns to normal, the components contract or expand to form a tight, permanent bond. This process is reversible by reheating the outer part, and it avoids the deformation that can occur with press fits.
Shroud – It is a protective, refractory-lined metal-delivery system to prevent reoxidation of molten steel when it is poured from ladle to tundish to mould during continuous casting.
Shunt – It is a small value resistor which is connected around a metering element to carry most of the current, only a small part passes through the meter.
Shunt capacitance – It refers to the capacitance which exists between a conductor and ground, or between different conductors in a circuit, and is frequently considered a parasitic effect. In electrical systems, particularly in long transmission lines, this capacitance can cause charging and discharging currents, affecting voltage levels and reactive power flow.
Shunt motor – It is a type of direct current motor where the field winding and armature winding are connected in parallel (shunt). This means both windings receive the same supply voltage, and the field current remains relatively constant regardless of the load, resulting in a motor that maintains a near-constant speed even under varying loads.
Shunt resistance – It refers to a low-resistance path created in parallel with another component or circuit element. It is typically used to divert a portion of the current, frequently to extend the range of an ammeter or to protect a circuit from overcurrent. In solar cells, shunt resistance can also refer to unintended low resistance paths which can lead to power loss and hotspots.
Shut height – For a metal forming press, It is the distance from the top of the bed to the bottom of the slide with the stroke down and adjustment up. In general, it is the maximum die height that can be accommodated for normal operation, taking the bolster plate into consideration.
Shut-off valve – It is a valve designed only for on / off service. It is not a throttling valve. It is sometimes referred to as a ‘block valve’. It is a type of valve which is designed to completely stop or start the flow of a fluid, whether it is liquid, gas, or slurry, in a system. It is essentially a device which can be used to isolate sections of a pipeline for maintenance, repairs, or to prevent further damage in an emergency.
Shuttle conveyor – It is a belt conveyor having over-end discharge, the whole being mounted on a travelling carriage capable of being shuttled backwards and forwards.
Shuttle valve – It also known as a double-check valve. It allows pressure in a line to be obtained from alternative sources. It is primarily a pneumatic device and is rarely found in hydraulic circuits. Construction is very simple and consists of a ball inside a cylinder.
Side chain – It is a chemical substituent group which is attached to the core part or ‘backbone’ of a larger molecule, especially an oligomeric or polymeric hydrocarbon chain which branches off of the longer primary chain of a macromolecule. The term is most commonly encountered in bio-chemistry and organic chemistry.
Side-channel pump – It is a type of regenerative turbine pump. It has a suction disk, an impeller, and a discharge disk.
Side channels – These are structural elements designed to bolster and uphold the rollers situated on the lateral sides of the conveyor. Periodic inspections are vital to ascertain the robustness and alignment of side channels, ensuring the seamless functionality of the roller system.
Side crack – It consists of edge(s) containing crack, split, and / or tear caused by the inability to deform without fracturing.
Side cutting edge angle – In a single-point cutting tool, it is the angle between the side cutting edge and a line parallel to the tool shank. It is also known as the lead angle or principle cutting angle. This angle is crucial in controlling the chip width during machining
Side-flexing steel flat-top chain -It is similar to the straight-running steel flat-top chain with one major difference. The barrels in which the pins are free to turn are specially formed to permit the joint to flex sideways. Hence, the chain can flex in two planes. The amount of side flexing is limited so that the chain retains enough strength and bearing area to work well as a conveyor. As a side-flexing chain is pulled around a curve, it is frequently pulled up and out of the track. Hence, side-flexing flat-top chains have bevels or tabs to hold them down in the tracks as they round a curve. Also, as side-flexing chains operate, material is worn off the bevels or tabs of the top plates and the curved sections of track. As this type of wear progresses, the bevels or tabs may break off, allowing the chain to jump out of the track.
Side milling – It means milling with cutters which are having peripheral and side teeth. They are normally profile sharpened but can be form relieved.
Side mount drive – It is an integrated drive mechanism affixed to the lateral aspect of the conveyor, typically utilized in situations where minimal elevations are a prerequisite. Consistent checks are crucial to validate the efficient operation, lubrication, and overall alignment of side mount drives.
Side rail – It is a supportive framework flanking the conveyor’s sides, serving to direct and confine transported materials. Routine examinations are essential to sustain the structural integrity, alignment, and safety attributes of side rails, ensuring optimal conveyor performance.
Siderite – It is Iron carbonate, which when pure, contains 48.2 % iron. It is to be roasted to drive off carbon di-oxide before it can be used in a blast furnace. Roasted product is called sinter.
Siderite ores – These ores consist of beds of siderite or siderite nodules associated with shales. They are common in the coal measures and are frequently termed clay ironstones or black band ironstones. These ores normally contain associated sulphides and frequently have a fairly high sulphur and phosphorus content.
Side roller – It is a specialized roller strategically positioned along the sides of the conveyor, dedicated to guiding and providing support to the conveyor belt. Ongoing inspections are vital to authenticate the condition and alignment of side rollers, safeguarding against potential deviations.
Side scraper reclaimer – Side scraper reclaimer is suitable for reclaiming sticky materials. However, since the side scraper reclaimer reclaims material from side of the pile, it is suitable for buffer storage (non-blending) application only. The side scraper can reclaim a pile completely. As the machine rides on / over stockpile, it can move to any area of the pile and start reclaiming or can move to any of the stockpiles in series. Side scraper reclaimer is the most economical solution for small stockyards up to the pile width spans of 30 meters. It is used both for open as well as covered stock yards. It is used extensively for low-capacity non-blending applications. It is also called a pylon or cantilever scraper. The side scraper reclaimer travels on a track arranged along one side of the stockpile. Two parallel strands of chain running on chain guides are installed on boom of the reclaimer. The scraper blades are mounted onto the two strands of the chain at regular interval. The boom is provided with a pivot which is located at the discharge end near the base of the stockpile. A winch using a wire rope and sheave system is used to lift the free end of the boom to place it on the side of the stockpile. At tail end, the chains pass around tail sprockets, and at the head / discharge end pass around driven sprockets. The scraper blades reclaim the material from side of the stockpile and convey it to the discharge point above the outgoing conveyor through an inclined drag trough.
Side set – It means a difference in thickness between the two edges of plate, sheet, or foil.
Side tables – These are sturdy steel platforms affixed to either side of the conveyor bed, offering a convenient working surface in close proximity to the conveyor. Regular checks are indispensable to ensure the stability, alignment, and effectiveness of side tables, facilitating efficient operational tasks.
Side thrust – It is the lateral force exerted between the dies by reaction of a forged piece on the die impressions.
Siegbahn notation – It is a system used in X-ray spectroscopy to name and categorize the characteristic X-ray lines emitted by different elements. It provides a way to identify the energy levels of electrons in atoms, particularly within inner shells, by observing the transitions of electrons between these shells. These transitions are triggered when an electron jumps from a higher energy level to fill a vacancy created in a lower energy level.
Siegel-Tukey test – It is a non-parametric test named after Sidney Siegel and John Tukey, which tests for differences in scale between two groups. Data measured is to be at least be ordinal.
Siemens – It is a unit of electrical conductivity. One siemens of conductance per cubic meter with a potential of 1 volt allows the passage of 1 ampere current per square meter. It is a reciprocal ohm, the SI (International System of Units) unit of conductance. The former Siemens mercury unit was a unit of resistance.
Siemens entrained-flow gasifier (SFG) – It is a type of gasification reactor which operates under high temperatures and pressures, using a turbulent flow to convert various solid fuels into syngas (a mixture of gases like carbon mono-oxide and hydrogen). The Siemens Fuel Gasifier (SFG) is known for its ability to handle a wide range of fuels, including lower-rank coals like lignite, and produces a clean syngas free of higher hydrocarbons.
Siemens-Martin process – It is also known as the open-hearth process. It is a method of steelmaking which has been widely used in the 19th and 20th centuries. It involves melting pig iron and scrap steel in a large, shallow furnace, with the heat being supplied by burning fuel over the charge. The process is named after its inventors, William Siemens and Pierre-Émile Martin. The process utilizes a reverberatory furnace, where a flame is directed over the charge to heat it.
Siemens process – It is a method for producing high-purity poly-silicon through the deposition of silicon from a mixture of purified silane or tri-chloro-silane gas with hydrogen onto heated filaments in an insulated reaction chamber, operating at temperatures between 1,100 deg C to 1,175 deg C. This process is critical for ensuring uniform deposition necessary for semiconductor and solar applications.
Sieve – It is a standard wire mesh or screen which is used in graded sets to determine the mesh size or particle size distribution of particulate and granular solids.
Sieve analysis – It is a method of determining particle size distribution. It is normally expressed as the weight percentage retained upon each of a series of standard screens of decreasing mesh size.
Sieve classification – It is the separation of powder into particle size which ranges by the use of a series of graded sieves. It is also called screen analysis.
Sieve drive – It is a pioneering conveyor propulsion system deriving its power not from an autonomous prime source but ingeniously harnessed from a companion conveyor. This innovative drive mechanism interlinks conveyors, optimizing efficiency and reducing individual power dependencies. Regular evaluations are imperative to ensure seamless power transfer and sustained operational synergy.
Sieve fraction – It is that portion of a powder sample which passes through a sieve of specified number and is retained by some finer mesh sieve of specified number.
Sievert (Sv) – The Sievert is the international system (SI) derived unit for a dose equivalent to 1 Joule per kilogram. 1 Sievert = 100 rem (roentgen equivalent man). It is named after Rolf Sievert, a Swedish physicist famous for work on the biological effects of radiation. The effective dose in Sieverts is calculated as the absorbed dose measured in Gy (Gray) multiplied by a weighting factor specific to each type of radiation and organ.
Sievert’s law – It states that, at a given temperature, the solubility of a diatomic gas in a liquid metal or a solid is proportional to the square root of its partial pressure. This is since the gas molecules dissociate into atoms upon dissolving, and the concentration of these dissolved atoms is proportional to the square root of the gas’s pressure. As an example, the solubility of hydrogen in metals is governed by Sievert’s law, where the concentration of hydrogen in the metal is proportional to the square root of the hydrogen gas’s partial pressure.
Sieve shaker – It is a device which is used to automate the separation and size determination of particles by applying agitation (shaking, knocking, and vibrating) to a stack of sieves. It helps in particle size analysis by separating particles based on their size as they pass through progressively smaller openings in the sieves.
Sieve undersize – It refers to the material which passes through a sieve opening of a specific size. It is the portion of a sample which is smaller than the mesh size used in the sieving process. It also means the underside of a mesh to which loose powder frequently adheres. For ensuring accuracy of the sieve analysis, this material is to be removed and included in the weight determination.
Sigma – It is the eighteenth letter of the Greek alphabet. Upper case sigma is used as a symbol for mathematical sum, while lower case sigma is used as a symbol for standard deviation.
Sigma bonding – It is covalent bonding between atoms in which ‘s’ orbitals or hybrid orbitals between ‘s’ and ‘p’ electrons overlap in cylindrical symmetry along the axis joining the nuclei of the atoms.
Sigma methodology – It is a collection of methods, techniques, and tools for process improvement, originally rooted in statistical concepts introduced by Carl Friedrich Gauss and further developed by Walter Shewhart, culminating in the Six Sigma framework established by engineers at Motorola.
Sigma phase – It is a hard, brittle, nonmagnetic intermediate phase with a tetragonal crystal structure, containing 30 atoms per unit cell, space group, P4/mnm (International Symbol 136), occurring in many binary and ternary alloys of the transition elements. The composition of this phase in the different systems is not the same, and the phase normally shows a wide range in homogeneity. Alloying with a third transition element normally enlarges the field homogeneity and extends it deep into the ternary section.
Sigma-phase embrittlement – If is embrittlement of iron-chromium alloys (most notably austenitic stainless steels) caused by precipitation at grain boundaries of the hard, brittle intermetallic phase during long periods of exposure to temperatures between approximately 560 deg C and 980 deg C. Sigma-phase embrittlement results in severe loss in toughness and ductility and can make the embrittled material susceptible to inter-granular corrosion.
Sigmoid function – It is defined as a mathematical function which transforms a continuous real number into a range of (0, 1). It is normally used in neural networks as an activation function, where small input values result in outputs close to 0 and large input values result in outputs close to 1. Its characteristic S-shaped curve makes it particularly useful in scenarios where people need to convert outputs into probabilities. This function is frequently called the logistic function. Sigmoid function is used as an activation function in machine learning and neural networks for modeling binary classification problems, smoothing outputs, and introducing non-linearity into models.
Signal – It consists of some intentional modification of a physical communication path which is intended to convey information from one place to another.
Signal detection – It is the process of measuring and storing information from sensor output to provide warning and diagnostic information, involving components such as amplifiers, filters, and data acquisition systems. It analyzes signal characteristics to assess the presence and behaviour of charged particles in a monitored environment.
Signal factors – A signal factor is a controllable factor which is adjusted during use to affect the output or response of a system. It represents the intended input or stimulus that the user directly controls to achieve a desired outcome. Unlike control factors, which are adjusted during the experiment to find optimal settings, signal factors are varied to see how the system responds across a range of input levels. Signal factors are the factors which can be adjusted by the user to attain the target performance. Steering angle, for example, is a signal factor for the steering mechanism of an automobile.
Signal-flow graph – It is a formal mathematical treatment of the representation of signal flow through a system, such as an analog computer or a radio receiver.
Signal input – It is information or energy fed into a system to produce a desired response. It can take several forms, such as voltage, current, light, or other physical quantities, and dictates how the system behaves. Essentially, it i’s the starting point for any system, influencing its output.
Signal intensity (SI) – It refers to the magnitude or strength of a detected signal, which is a measure of the power or amplitude of that signal. It can also represent the density of energy at a specific point in space, such as with sound intensity, or the degree of concentration of a substance or phenomenon, as seen in spectroscopy or magnetic resonance.
Signal processing – It is the technology to extract information from signals. It is an electrical engineering sub-field which focuses on analyzing, modifying and synthesizing signals, such as sounds, images, images, potential fields, seismic signals, altimetry processing, and scientific measurements. Signal processing techniques are used to optimize transmissions, digital storage efficiency, correcting distorted signals, improve subjective video quality, and to detect or pinpoint components of interest in a measured signal.
Signal processing instruments – These are devices or systems designed to analyze, modify, and / or synthesize signals. These instruments utilize several techniques to extract meaningful information from signals, optimize their transmission or storage, and correct or enhance them. Common examples include audio processors like compressors, equalizers, and reverberation units, as well as instruments used in fields like telecommunications, medical imaging, and scientific measurements.
Signal quality – It is the determination of the quality of a spectroscopic signal, which can be assessed using the signal-to-noise ratio, and is influenced by factors such as optical noise, scattering effects, and measurement reproducibility.
Signal strength – It is a measure of the usable power of a physical signal.
Signal-to-noise ratio – It is a measure of the power contained in the useful part of the signal, to the power contained in noise. It is frequently measured in decibels, e.g., in sound reproduction a 40 decibel or 50 decibel signals to noise ratio is broadcast quality, whereas a 10 decibels ratio represents very difficult operating conditions for a voice radio system.
Signal transmission and conditioning – A wide variety of phenomena are used to measure the process variables required to characterize the state of a process. Because most processes are operated from a control room, these values are to be available there. Hence, the measurements are usually transduced to an electronic form, most often 4-20 mA, and then transmitted to a remote terminal unit and then to the control room. It is especially important that proper care is taken so that these measurement signals are not corrupted owing to ground currents, interference from other electrical equipment and distribution, and other sources of noise.
Significance – An effect is significant if the value of the statistic used to test it lies outside acceptable limits, i.e., if the hypothesis that the effect is not present is rejected.
Significance level – It is the stated probability (risk) which a given test of significance rejects the hypothesis that a specified effect is absent when the hypothesis is true.
Significance level, of a hypothesis test – The significance level of a statistical hypothesis test is a probability of wrongly rejecting the null hypothesis H0, if it is in fact true. It is the probability of a type I error and is set by the investigator in relation to the consequences of such an error. That is, one wants to make the significance level as small as possible in order to protect the null hypothesis and to prevent the investigator from inadvertently making false claims. Normally, the significance level is chosen to be 0.05 (or equivalently, 5 %).
Significant – Statistically an effect of difference between populations is said to be present if the value of a test statistic is significant, i.e., lies outside predetermined limits.
Significant cost reduction – It is the process of achieving substantial, permanent reductions in product or project costs by modifying design, materials, or processes without sacrificing fit, form, or function. It aims to increase profitability and competitiveness by improving productivity, eliminating waste, and identifying more cost-effective materials or manufacturing methods. Key principles include focusing on the early stages of design, where the majority of costs are determined, and ensuring reductions are real and sustainable, not just temporary fixes.
Sign test – It is a test which can be used whenever an experiment is conducted to compare a treatment with a control on a number of matched pairs, provided the two treatments are assigned to the members of each pair at random.
Sila-hydrocarbon fluids – These fluids are a class of liquid lubricants which consist of silicon, carbon, and hydrogen atoms. These are a type of lubricant, a substance used to reduce friction and wear between moving surfaces. They are specifically designed to be liquid lubricants with unique properties, frequently used in aerospace and other demanding applications. Sila-hydrocarbons are unimolecular, have exceptionally low volatility, high viscosity indices and are available in a wide range of viscosities. There are three types namely tri, tetra, and penta, based on the number of silicon atoms present in the molecule. Additionally, sila-hydrocarbons can accept conventional lubricant additives. Sila-hydrocarbon fluids are known for their good wear, viscosity, and volatility properties, making them suitable for use in extreme environments like space, where conventional lubricants do not perform well. Their ability to solubilize conventional antiwear additives also contributes to their effectiveness.
Silane – It is an inorganic compound with chemical formula SiH4. It is a colourless, pyrophoric gas with a sharp, repulsive, pungent smell, somewhat similar to that of acetic acid. Silane is of practical interest as a precursor to elemental silicon.
Silane coating – It is a surface treatment which utilizes silane-based materials to form strong bonds with metal substrates, providing very good adhesion and corrosion protection through the creation of cross-linked polymer networks and dense siloxane structures.
Silent chain – This chain is also called ‘inverted tooth’ chain. It consists of a series of toothed link plates assembled on joint components in a way that allows free flexing between each pitch. The large majority of silent chain is used in drives. Silent chains are made up of stacked rows of load carrying link plates. Increasing the number of rows of links increases the chain width, tensile strength, and load carrying capacity. Silent chains are made up of stacked rows of flat link plates with gear-type contours designed to engage sprocket teeth in a manner similar to the way a rack engages a gear. The links are held together at each chain joint by one or more pins, which also allow the chain to flex. The design of both the link contour and the chain joint directly influences a chain’s useful load carrying capacity, its rate of wear and service life, and its quietness of operation.
Silica – It is silicon di-oxide (SiO2). Quartz is a common example. It is the main ingredient of sand and acid refractories.
Silica aggregate – It is a collection of rock particles, mineral crystals, or particles which are mainly composed of silica (SiO2) or silicate minerals containing silica. These aggregates are important in several industries, especially in concrete and glass manufacturing, where their high silica content gives them specific structural and chemical properties.
Silica brick – It is a type of high-refractory brick, mainly composed of silica (SiO2) with silica content ranging at least 93 % to 96 %. It is designed for high-temperature applications like furnaces, kilns, and glass manufacturing because of its excellent thermal and chemical resistance. These bricks are known for their ability to maintain volume stability at high temperatures, resist acid slag erosion, and provide insulation, making them crucial components in industrial high-temperature environments. Silica refractory brick is the most abundant refractory used in the construction of a coke oven battery (COB). Silica is the refractory of choice mainly since, at normal coke oven battery operating temperatures, silica refractories are subject to minimal creep. Also, since nearly all of the expansion of silica brick takes place below 650 deg C, during normal operation of a coke oven battery, the moderate temperature fluctuations of the walls have no effect on the volume stability of the refractory comprising the wall. A coke oven battery design can have well over 400 different shapes used in its construction. These shapes are installed with a silica mortar. Since the later part of 1950s there had been a general trend to use high bulk density (BD) silica bricks (bulk density higher than 1,850 kilograms per cubic meter) in coke oven battery construction. Increase of bulk density is accompanied by corresponding increases in cold strength and thermal conductivity. Other than coke oven battery, silica bricks are used mainly in glass melting furnaces, hot blast stoves, and electric arc furnace roofs.
Silica fibres – These are defined as synthetic fibres made of silica through chemical vapour deposition, characterized by high transparency in the infrared spectrum, particularly below 2 micro-meters, and are normally used in telecommunications systems.
Silica flour – It is a sand additive, containing around 99.5 % silica, normally produced by pulverizing quartz sand in large ball mills to a mesh size of 80 to 325.
Silica fume – It is also known as micro-silica It is a by-product of silicon and ferro-silicon alloy production, consisting of extremely fine, non-crystalline silica particles. It is basically a very fine powder, around 100 times smaller than cement particles, formed when silicon vapour condenses during the smelting process. Because of its high surface area and chemical composition, it is a highly reactive pozzolanic material used to improve concrete properties.
Silica gel – It is a colloidal form of silica used as a drying agent.
Silica membranes – These are a type of inorganic membrane used for hydrogen / carbon di-oxide separation, characterized by a system of micro-pores allowing gas transport through site-hopping diffusion, and typically consist of selective, intermediate, and support layers. They are less expensive and easier to fabricate than metallic membranes but lack complete selectivity for specific components.
Silica mortar – It is mainly composed of the silica mineral quartz. In general, there are two types of mortar used, an air setting, which contains a small amount of sodium silicate, and a heat setting, which is basically the same mortar, but without the sodium silicate. Both the types of silica mortar typically do not bond to the silica brick at normal battery operating temperatures. Therefore, it does not impart any strength to the wall. Also, since the primary mineral constituent in the mortar is quartz, the mortar is not volume stable. The quartz in silica mortar installed in an operating battery slowly converts to the high temperature forms of silica—tridymite and cristobalite—during normal battery operation. This conversion is accompanied by a significant increase in volume. This conversion happens first on the hotter flue side of the wall. This means that the mortar in the horizontal joints assumes a wedge shape; thicker on the flue side and thinner on the oven side of the wall.
Silica ramming mass (SRM) – It is a type of refractory material, a high-purity silica-based material which is used as lining in induction furnaces. It is mainly composed of silicon carbide (SiC), silica (SiO2), and other components, which are crushed and ground into fine particles after a chemical reaction between carbonaceous material and molten metal.
Silica refractories – Silica refractories comprise of silicon oxide (SiO2) also known as silica. These refractories are produced either from quartz or fused silica. Silica refractories contain at least 93 % silicon oxide. The raw material is quality rocks. Various grades of silica brick have found extensive use in the iron and steel industry furnaces. In addition to high fusion point multi-type refractories, the other important properties of silica refractories are their high resistance to thermal shock (spalling) and their high refractoriness. The outstanding property of silica brick is that it does not begin to soften under high loads until its fusion point is approached. Other advantages are flux and slag resistance, volume stability and high spalling resistance.
Silica sand – It is the sand with a minimum silica content of 95 % used for forming casting moulds.
Silicate – It is one of the members of a family of poly-atomic anions consisting of silicon and oxygen. The family includes ortho-silicate, meta-silicate, and pyro-silicate. The name is also used for any salt of such anions, such as sodium meta-silicate, or any ester containing the corresponding chemical group, such as tetra-methyl ortho-silicate. The name ‘silicate’ is sometimes extended to any anions containing silicon, even if they do not fit the general formula or contain other atoms besides oxygen, such as hexa-fluoro-silicate. Very frequently, silicates are encountered as silicate minerals. For diverse manufacturing, and technological needs, silicates are versatile materials, both natural (such as granite, gravel, and garnet) and artificial (such as Portland cement, ceramics, glass, and water-glass).
Silicate esters – These are a class of chemical compounds derived from silicic acid and alcohols. They are known for their thermal stability, low viscosity, and high di-electric strength, making them useful in several applications, including lubrication. While not as commonly used as silicones in some lubrication applications, they offer specific advantages, particularly in high-temperature and low-temperature environments.
Silicate glasses – These are a type of glass where silica (silicon di-oxide, SiO2) is the main component, forming a three-dimensional network of corner-shared SiO4 (ortho silicate) tetrahedra. These glasses are characterized by their ability to transition reversibly from a liquid to a rigid state without forming a new phase, exhibiting a glass transition temperature (Tg). Basically, they are glasses rich in silica and are the most common type of glass.
Silicate inclusions – These inclusions are present in steel like a glass formed with pure silicon oxide (SiO2) or silicon oxide with admixture of iron, manganese, chromium, aluminium, and tungsten oxides and also crystalline silicates. Silicates are the biggest group among non-metallic inclusions.
Silicate minerals – These are a group of minerals characterized by the presence of silicon and oxygen, typically combined with other elements like metals. They are the most abundant minerals in earth’s crust, forming the foundation of several rocks and geological formations. The fundamental building block of all silicates is the silicon-oxygen tetrahedron (SiO4), a structure with one silicon atom surrounded by four oxygen atoms.
Silicates – These are a vast class of chemical compounds mainly found in minerals, consisting of silicon and oxygen, frequently along with other elements. They are characterized by the presence of the fundamental SiO4 tetrahedron, where a silicon atom is at the centre and four oxygen atoms are at the corners. These tetrahedra can be linked together in several ways, forming complex structures which constitute the majority of the earth’s crust.
Silica wash – It is silica flour mixed with water and other materials to form a brushable or sprayable facing material.
Siliceous – It is a rock containing an abundance of quartz.
Siliceous refractory – It is the refractory which contains less than 93 % and higher than or equal to 85 % by mass of silica.
Silico-ferrite of calcium and aluminum (SFCA) – It is a crystalline phase in sinter. It is also known as calcium alumino-silico-ferrite or calcium aluminate ferrite. It is identified as a solid solution of CaO.2Fe2O3 with small quantities of dissolved Al2O3 (aluminum oxide) and SiO2 (silicon oxide). It is considered as a complex quaternary phase. It forms in high basicity iron ore sinter. It is a key bonding phase in high basicity sinters, playing a crucial role in their strength and stability. Alumina (Al2O3) and silica (SiO2) are important for its formation, and understanding how these elements affect SFCA formation is key to optimizing sintering processes.
Silico-manganese – It a preferred ferroalloy during steel making. It has emerged as a more important alloy than ferro-manganese. It is used as substitute for low carbon ferro-manganese. It is also needed as a raw material to produce medium carbon ferro-manganese and low carbon ferro-manganese. The standard grade contains manganese in the range of 62 % to 68 %, silicon in the range of 12 % to 18 % and carbon in the range of around 2 %. The low carbon grade of silico-manganese has a carbon level of 0.1 % maximum. The production of silico-manganese is based on manganese ore or sinter and quartz as raw material. Instead of manganese ore, a rich ferro-manganese slag like that produced as rich slag in high carbon ferro-manganese, medium carbon ferro-manganese, and low carbon ferro-manganese production may be used as a manganese source. Silico-manganese is produced in submerged-arc furnaces which can be closed, semi-closed or open types. The furnaces are the same or very similar to those used for high carbon ferro-manganese production and frequently a furnace is operated with alternate campaigns of each alloy. According to the composition of the feed mix, silico-manganese with a silicon content from 12 % to 35 % can be produced. For proper furnace operation and effective silicon reduction, it is necessary to penetrate the electrodes deeper into the burden in order to reach the high temperature needed for the process.
Silicon (Si) – It is a chemical element having atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a tetravalent non-metal and semiconductor. It is relatively unreactive. Silicon is widely regarded as the predominant semiconductor material because of its versatile applications in several electrical devices such as transistors, solar cells, integrated circuits, and others. These can be because of its significant band gap, expansive optical transmission range, extensive absorption spectrum, surface roughening, and effective anti-reflection coating.
Silicon-aluminum – It is an alloy of 50 % silicon and 50 % aluminum which is used for making silicon additions to aluminum alloys’ It is also called an intermediate or hardener alloy. Its melting point is 577 deg C.
Silicon aluminum alloys– These are aluminum-based alloys with silicon as the main alloying element, known for their excellent casting properties, high fluidity, and wear resistance, making them ideal for automotive components like engine blocks and pistons. These alloys offer a lower melting point and reduced shrinkage compared to pure aluminum, while the hard silicon particles improve wear resistance, and additions of copper or magnesium can further improve their strength.
Silicon brass – It is a series of alloys containing 0.5 % to 6 % silicon, 1 % to 19 % zinc and a substantial quantity of copper.
Silicon bronze – It is a series of alloys containing 1 % to 5 % silicon, 0.5 % to 3 % iron, under 5 % zinc, under 1.5 % manganese, and the remainder being substantially copper.
Silicon carbide (SiC) – It is also known as carborundum. It is a hard, synthetic compound of silicon and carbon, which is used as both an abrasive and a semiconductor material, especially in power electronics because of its high thermal conductivity and ability to withstand high voltages. In composites, silicon carbide is the reinforcement, in whisker, particulate, and fine or large fibre, which has application as metal-matrix reinforcement because of its high strength and modulus, density equal to that of aluminum, and comparatively low cost. As a whisker or particulate, it gives the composite isotropic properties.
Silicon carbide briquettes – These consist of silicon carbide in briquette form which is used as an inoculant and deoxidizer in cupola-melted gray iron.
Silicon carbide metal-oxide-semi-conductor field-effect transistor (SiC MOSFET) – It is a type of power semi-conductor device which utilizes silicon carbide (SiC) as the semi-conductor material. Silicon carbide offers high thermal conductivity, a wide bandgap, and high breakdown voltage, making it suitable for high-power and high-temperature applications. Silicon carbide metal-oxide-semi-conductor field-effect transistors are voltage-controlled devices, meaning their conductivity is modulated by the voltage applied to the gate terminal.
Silicon carbide refractories – These are refractory products consisting predominantly of silicon carbide. These refractories are produced from silicon carbide (SiC), a raw material synthesized in a resistance-type electric furnace at temperature higher than 2,500 deg C, through the reaction of silica with carbon. These refractories are normally used in belly and bosh areas in modern blast furnaces.
Silicon cells – These are photo-voltaic devices made from silicon (Si) crystals, which are categorized into three main types namely mono-crystalline, poly-crystalline, and amorphous silicon cells. These cells are normally used to produce solar energy because of the abundance of silicon on earth and are continually developed to improve their performance and efficiency.
Silicon content – It refers to the proportion of silicon present in an alloy or mixture, which can considerably influence its physical properties, such as density, particularly in ferro-silicon (Fe-Si) alloys.
Silicon controlled rectifier – It is a four-layer semiconductor switching device which can stand off an applied voltage until triggered by an electrical pulse on a control lead.
Silicon-copper – It is an alloy of silicon and copper, used as a deoxidizer and hardener in copper-base alloys. It is available in two types containing 10 % and 20 % silicon.
Silicone – It is also called polysiloxane. It is a polymer composed of repeating units of siloxane (−O−R2Si−O−SiR2−, where R = organic group). They are typically colourless oils or rubber-like substances. Silicones are used in sealants, adhesives, lubricants, thermal and electrical insulation. Some common forms include silicone oil, grease, rubber, resin, and caulk.
Silicone acrylate (SA) – It refers to a type of polymer which consists of acrylate end-capped linear poly-dimethyl-siloxanes or silicone chains containing pendent acrylate groups, which are utilized as release coatings because of their versatility in cure speed, coatability, and release control for different applications.
Silicone fluids – These are silicone oils (poly-di-methyl-siloxane) used as lubricants because of their unique properties. These fluids are normally colourless transparent liquids. They show excellent resistance to heat, cold, and moisture. There is also little viscosity change in silicone fluids over a wide temperature range, and they have outstanding electrical properties. In addition, they are notable for their characteristics of mould-releasability, water repellency, lubricity, and defoaming properties.
Silicon electrical steel – It is a type of specialty steel created by introducing silicon during the steelmaking process. Electrical steel shows certain magnetic properties, which make it optimum for use in transformers, power generators, and electric motors.
Silicon electrical steel, grain-oriented – In it, the metal’s grain runs parallel within the steel, permitting easy magnetization along the length of the steel. Although grain-oriented steel can be twice as expensive to produce, its magnetic directional characteristics enable power transformers, made from this steel, to absorb less energy during operation.
Silicon electrical steel, non-grain-oriented – In this steel, since there is no preferential direction for magnetization, non-grain-oriented steel is best used in rotating apparatus such as electric motors.
Silicone oil – It is a liquid polymer composed of repeating units of silicon and oxygen atoms, with organic groups (like methyl or ethyl) attached to the silicon atoms. It is characterized by its transparency, colourless appearance, and resistance to heat, oxidation, and chemicals. These properties make it a versatile material used in several applications including the industrial processes.
Silicone plastics – These are plastics based on resins in which the main polymer chain consists of alternating silicon and oxygen atoms, with carbon-containing side groups. These are derived from silica (sand) and methyl chlorides and furnished in different molecular weights, including liquids and solid resins and elastomers.
Silicone rubber – It is a rubber prepared by the action of moisture on dimethyl di-chloro silane and other halo-silanes. They are characterized by serviceability at very low and very high temperatures.
Silicon filament – It can refer to different materials, normally either a fine fibre or wire of pure silicon used in the semi-conductor industry, or a thin, elongated structure of silicon or silicon-based material formed within a film for applications like solar cells or opto-electronics. In the semi-conductor context, filaments act as substrates for poly-silicon production, while in opto-electronics, they are used to manipulate light or create specific quantum effects within a larger material.
Silicon impact ionization avalanche transit-time diode – In it, electrons traverse the diode’s drift region after being generated by an avalanche process. This transit time, or the time it takes for electrons to move across the diode, is a key factor in the diode’s high-frequency behaviour. The avalanche process itself is triggered by a reverse-biased voltage across the diode, creating electron-hole pairs through collisions.
Silicon-infiltrated silicon carbide (SiSiC) – It is a ceramic composite material created by infiltrating molten silicon into a pre-formed silicon carbide / carbon structure. This process results in a dense, high-strength material with improved thermal and mechanical properties, making it suitable for various high-temperature applications.
Silicon intensified target camera tube – It is a type of camera tube which is used for low-light imaging. It works by converting photons into electrons, which are then accelerated onto a silicon target, creating a high number of electron-hole pairs. This amplification allows the tube to detect very faint light signals. The charges from the silicon target are then read out by an electron beam, generating a video signal.
Siliconizing – It means diffusing silicon into solid metal, normally low-carbon steels, at a high temperature in order to improve corrosion or wear resistance.
Silicon nano-crystals (Si-NC) – These are crystalline silicon particles with at least one dimension less than 100 nano-meters (nm), frequently ranging from 5 nano-meters to 10 nano-meters in diameter These show unique quantum confinement effects leading to light emission properties unlike bulk silicon. These luminescent properties are tunable by altering the nano-crystal’s size, surface chemistry, and doping, enabling applications in opto-electronics, energy storage, and sensing.
Silicon nitride – It is a ceramic compound, very frequently referring to the compound Si3N4 (tri-silicon-tetra-nitride), which is a high-temperature structural ceramic known for its strength, hardness, and thermal stability. It is used in several applications because of its resistance to high temperatures and wear.
Silicon oxide – It is also called silicon di-oxide (silica). It is an inorganic compound with the chemical formula SiO2. It consists of silicon and oxygen atoms and is a widespread substance found in nature as quartz, sand, and rock, making up a substantial portion of the earth’s crust. Silicon di-oxide has several forms, including crystalline and amorphous, and is used in many applications, such as in membranes, and in the manufacture of glass and optical parts.
Silicon solar cells – These are photo-voltaic devices made from crystalline silicon, which are characterized by their long-term stability, non-toxicity, and abundant availability. They dominate the photo-voltaic market and their production efficiency and cost reduction are key factors for continued success.
Silicon steel – It is also known as electrical steel or lamination steel. It is a type of alloy steel which is mainly used for its magnetic properties. It contains silicon as a major alloying element, typically in concentrations between 3 % and 5 %, which improves its soft magnetic properties. These properties make it suitable for applications in electrical machines like motors, generators, and transformers, where magnetic core materials are needed.
Silky fracture – It is a metal fracture in which the broken metal surface has a fine texture, normally dull in appearance. It is the characteristic of tough and strong metals.
Sill – It is an intrusive sheet of igneous rock of roughly uniform thickness which has been forced between the bedding planes of existing rock.
Sillimanite – It is also called fibrolite. It is an aluminosilicate mineral with the chemical formula Al2SiO5. Sillimanite is one of three alumino-silicate polymorphs, the other two being andalusite and kyanite. A common variety of sillimanite is known as fibrolite, so named because the mineral appears like a bunch of fibres twisted together when viewed in thin section or even by the naked eye. Both the fibrous and traditional forms of sillimanite are common in metamorphosed sedimentary rocks. It is an index mineral indicating high temperature but variable pressure.
Sillimanite refractories – These are refractory materials, typically bricks, made from the aluminosilicate mineral sillimanite (Al2SiO5). They are known for their high alumina content, high refractoriness under load, and resistance to heat shock. Sillimanite bricks are frequently used in high-temperature applications like glass furnaces, melting furnaces, and kilns.
Sill line – In the electric arc furnace), the sill line refers to the lower refractory brick lining within the furnace, specifically the level at which the bricks are arranged. This line defines the bottom surface of the furnace where the steel is melted and refined.
Silos – Silos are tall cylindrical structures normally made of reinforced concrete. These are used for storage of materials like coal and coke etc.
Silt – It is muddy deposits of fine sediment normally found on the bottoms of lakes.
Siltation – It is the deposit of material in a water-body by sedimentation.
Silver (Ag) – It is a chemical element having atomic number 47. A soft, whitish-gray, lustrous transition metal, it shows the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. Majority of silver is produced as a byproduct of copper, gold, lead, and zinc refining. Silver is a naturally occurring element. It is found in the environment combined with other elements such as sulphide, chloride, and nitrate. Pure silver is ‘silver’ coloured, but silver nitrate and silver chloride are powdery white and silver sulphide and silver oxide are dark-gray to black. Silver is frequently found as a by-product during the retrieval of copper, lead, zinc, and gold ores.
Silver 1 finish – Silver finish is also called satin finish. This surface finish is dull finish. In this type of finish the surface roughness (Ra) is aimed at 1 micro-meter. This finish is mainly used for making artistic canisters.
Silver 2 finish – This surface finish is rough and dull finish. In this type of finish the surface roughness (Ra) is aimed at 2.5 micro-meters. This finish is mainly used for making artistic canisters.
Silver 3 finish – This surface finish is rough and dull finish. In this type of finish the surface roughness (Ra) is aimed at 3 micro-meters. This finish is mainly used for making artistic canisters.
Silver alloy brazing – It is a non-standard term for brazing with a silver-base filler metal.
Silver ore – It is a naturally occurring rock or deposit containing a sufficient concentration of silver minerals, such as argentite (Ag2S) or chlorargyrite (horn silver), to be mined and processed profitably. While some deposits are silver-specific, silver frequently occurs as a contaminant within other metal ores, particularly copper, lead, and zinc.
Silver plating – It is a process in which other base metals are coated with a layer of silver. The process sounds simple, but it still needs to ensure that the base metal has an even layer of silver to gain that widely known and craved matte-white look.
Silver soldering – It is non-preferred term which is used to denote brazing with a silver-base filler metal. The preferred terms are furnace brazing, induction brazing, and torch brazing.
Silver streak – It is also called splay mark. It is a cosmetic imperfection which is normally observed on smooth-surfaced plastic parts. Silver streaking meaning is the splatter markings on product surfaces generated by air and moisture volatilization or mixed dissimilar polymers decomposing and burning. The term ‘silver streak’ is derived from the metallic scratches which appear on the surface of the injection-moulded component. A water wave pattern can form after moulding or shaping, which is difficult to remove. It can also reduce the strength of the final product. Silver streaks in injection moulding can be classified into five different types based on how they appear on the plastic surface. Analyzing the pattern of these lines, one can identify the root causes which lead to this error.
Silvery iron – It is a type of pig iron which containing 8 % to 14 % silicon, 1.5 % carbon maximum, 0.06 % sulphur maximum, and 0.15 % phosphorus maximum.
Simple alkenes – These are also known as olefins. These are defined as partially unsaturated straight-chain hydrocarbons characterized by one or two double carbon–carbon bonds, with the general formula CnH2n. They are named by changing the suffix of alkanes from -ane to -ene, reflecting the presence of a double bond.
Simple beam theory – It is a simplified model used in structural mechanics to analyze the behaviour of beams under different loads. It assumes the beam is initially straight and has a constant cross-section, made of homogeneous material, and that the applied loads are within the plane of symmetry. The theory focuses on bending and assumes plane sections remain plane after bending, and the stress-strain relationship is linear and elastic.
Simple harmonic motion (SHM) – It is a motion where the force acting on a body, and hence its acceleration, is proportional to and opposite in direction from the displacement from its equilibrium position.
Simple lattices – These are having similar atoms or groups of atoms separated by integral translations only.
Simple machine – It is a mechanical device that changes the direction or magnitude of a force. In general, they can be defined as the simplest mechanisms that use mechanical advantage (also called leverage) to multiply force. Normally the term refers to the six classical simple machines which were defined by Renaissance scientists. These six machines are lever, wheel and axle, pulley, inclined plane, wedge, and screw. A simple machine uses a single applied force to do work against a single load force. Ignoring friction losses, the work done on the load is equal to the work done by the applied force. The machine can increase the quantity of the output force, at the cost of a proportional decrease in the distance moved by the load. The ratio of the output to the applied force is called the mechanical advantage.
Simple random sample – It is a sample in which every member of the population has the same chance of being selected into the sample.
Simplification of design – It refers to the process of reducing the complexity of a system or component, which can be achieved through strategies such as integrating major components within the reactor vessel and minimizing the number and type of components, resulting in cost savings and material reduction compared to larger reactors.
Simulated service testing – It is the most reliable predictor of corrosion behaviour short of actual service experience. This includes exposures of either structural components or test samples in outdoor environments which are representative of several general service situations. These so-called natural environments include exposures to the atmosphere, waters, and soil. Test materials are subjected to the cyclic effects of the weather, geographical influences, and bacteriological factors which cannot be realistically duplicated in the laboratory. This type of testing is important for such objectives as materials selection, predicting the probable service life of a product or structure, evaluating new commercial alloys and processes, and calibrating laboratory corrosion tests. This type of information sought determines the selection of test specimens and the methods of assessing the corrosion effects.
Simulation – It is an imitative representation of a process or system which can exist in the real world. In this broad sense, simulation can frequently be used inter-changeably with model. Sometimes a clear distinction between the two terms is made, in which simulations need the use of models, the model represents the key characteristics or behaviours of the selected system or process, whereas the simulation represents the evolution of the model over time. Another way to distinguish between the terms is to define simulation as experimentation with the help of a model. This definition includes time-independent simulations. Frequently, computers are used to execute the simulation. Simulation is used in several contexts, such as simulation of technology for performance tuning or optimizing, safety engineering, testing, training, and education. Simulation is also used with scientific modelling of natural systems to gain insight into their functioning, as in economics. Simulation can be used to show the eventual real effects of alternative conditions and courses of action. Simulation is also used when the real system cannot be engaged, since it is not be accessible, or it is dangerous or unacceptable to engage, or it is being designed but not yet built, or it simply does not exist.
Simultaneous engineering – It is a style of product design and development which is done by concurrently utilizing all of the relevant information in making each decision. It replaces a sequential approach to product development in which one type of information is predominant in making each sequential decision. Simultaneous engineering is carried out by a multi-functional team which integrates the specialties or functions needed to solve the problem. It is also called concurrent engineering.
Sine curve – It is a mathematical function which represents the smooth oscillation of values, ranging from -1 to 1, and is used in applications such as ease-in / ease-out animations to create gradual acceleration and deceleration.
Sine law – It is also known as the Sine rule. It is a relationship in trigonometry which applies to any triangle, not just right-angled triangles. It states that the ratio of the length of a side of a triangle to the sine of its opposite angle is the same for all three sides and angles.
Sines-criterion – It is a fatigue failure prediction model which considers both hydrostatic stress and deviatoric stress in the context of fatigue loading. It is a stress-based criterion which calculates the equivalent nominal stress amplitude, taking into account both the octahedral shear stress and the hydrostatic stress value. Essentially, it is a method for estimating fatigue sensitivity by considering a linear combination of mean hydrostatic stress and alternate deviatoric stress.
Sine wave – It is the waveform of the mathematical sine function. It is a fundamental wave shape, free of harmonics.
Single-action press – It is a metal forming press which provides pressure from one side.
Single basket hitch configuration – This configuration is used to support a load by attaching one end of the sling to the hook, then passing the other end under the load and attaching it to the hook. In this hitch, it is to be ensured that the load does not turn or slide along the rope during a lift.
Single bevel grove weld – It is a type of groove weld.
Single billet furnace – It is a type of heating furnace mainly used in metal-working, specifically for preheating individual aluminum billets or logs before an extrusion process. It is designed to efficiently and precisely raise the temperature of a single billet to the desired level for extrusion.
Single bond – It is a bond which involves the sharing of one pair of electrons.
Single choker hitch configuration – It forms a noose in the sling. It does not provide full 360-degree contact with the load. Hence it is not to be used to lift loads difficult to balance or loosely bundled. Choker hitches are useful for turning loads and for resisting a load which wants to turn. Use of the choker hitch with two legs provides stability for longer loads. Like the single choker, this configuration does not completely grip the load. The load is to be lifted horizontally with slings of even length to prevent the load from sliding out.
Single-circuit winding – It is a winding in which the filament path makes a complete traverse of the chamber, after which the following traverse lies immediately adjacent to the previous one.
Single crystal – It is a solid material where the ordered atomic structure (the crystal lattice) extends uninterrupted throughout the entire volume, with no grain boundaries or other defects. This means the repeating pattern of atoms in the unit cell is consistent across the whole crystal.
Single-crystal X-ray diffraction (SCXRD) – It is a technique which is used to determine the three-dimensional structure of a molecule by analyzing the diffraction pattern produced when a single crystal is exposed to X-rays. This method provides detailed information about atomic positions, bond lengths, and angles within a crystal, allowing scientists to understand the arrangement of atoms and molecules in a crystal.
Single-edge notched (SEN) sample – It is a test sample used in fracture mechanics research, typically with a single, sharp notch machined into one edge of the specimen. This notch is designed to initiate a crack when the sample is subjected to a load, allowing researchers to study the material’s resistance to crack propagation. Single-edge notched samples are normally used in tests like single-edge notched bend (SENB) and single-edge notched tension (SENT).
Single-edge notched bend (SENB) test – It is a method used to assess a material’s fracture toughness by bending a rectangular beam with a single notch on one edge. The notch is placed on the bottom edge of the beam, halfway along its length, and the beam is subjected to a three-point bending load. This test helps determine the material’s resistance to crack propagation under bending stress.
Single-edge notched bending (SENB) sample – It is a rectangular beam with a single, sharp notch cut into one of its edges. It is a standardized geometry used in fracture toughness testing, particularly to determine the critical stress intensity factor (K1c) and the critical strain energy release rate (G1c). The sample is subjected to a three-point bending load, where the notch is placed at the point of maximum stress.
Single-edge notched tension (SENT) sample – It is a fracture mechanics test sample with a single, straight notch along one edge, designed to be subjected to tension loading. It is used to assess a material’s resistance to crack propagation and determine its fracture toughness. Single-edge notched tension samples are particularly useful for simulating the stress state of a flaw in a pipe under high strain conditions, making them well-suited for evaluating the fracture toughness of pipelines and similar structures.
Single-factor learning curve – It is also known as a single-factor experience curve. It is a model which describes the relationship between cumulative production and cost or time, typically used to analyze how efficiency improves with experience. It focuses on the impact of cumulative production volume on reducing costs or time, while only considering one independent variable namely cumulative production.
Single flare bevel groove weld – It is a weld in a groove formed by a member with a curved surface in contact with a planar member.
Single flare V-groove weld – It is a weld in a groove formed by two members with curved surfaces.
Single girder bridge crane – It consists of a single bridge girder supported on two end trucks. It has a trolley hoist mechanism which runs on the bottom flange of the bridge girder. Single girder cranes cost less since (i) only one girder is needed, (ii) the trolley is simpler, (iii) freight expenses are reduced, (iv) installation is faster, and (v) runway beams are lighter. However, not all cranes are to be designed with a single girder.
Single-hole die – It is an extrusion die with one hole, hence capable of producing just one extrusion per cycle.
Single impulse welding – It is a resistance welding process variation in which spot, projection, or upset welds are made with a single impulse.
Single J-groove weld – It is a type of groove weld.
Single lens reflex (SLR) camera – It is a type of camera which uses a mirror system to allow the photographer to view the image through the lens, just as it is going to be captured. This mirror reflects the light from the lens into the viewfinder, allowing the photographer to see what the lens is seeing before the photo is taken. When the shutter is pressed, the mirror flips up, and the light passes through to the film or digital sensor to record the image.
Single line diagram – It depicts the course of an electric or electronics circuit, or system of circuits, and the elements thereof using single lines, symbols, and notes. A single line diagram conveys basic information about the operation of the circuit, but omits much of the detailed information usually shown on schematic diagrams. The single line form of presentation provides for (i) simplified diagrams of complex circuits and (ii) diagrammatic representation of systems in which a single line represents a multi-conductor circuit. It includes (i) connections of major elements of a circuit represented by single line graphic symbols, (ii) the course of the main circuits (connection of major components) shown in the most direct path and logical sequence, and (iii) electrical characteristics which are essential to an overall understanding of the system.
Single-line orthographic pipe drawing – It represents a piping system using a single line to depict the pipe’s centerline, along with symbols for valves, fittings, and other components. This method is frequently used when speed and simplicity are important in conveying the basic layout of the system.
Single-loop controller – It is a control system which manages a single process variable, maintaining it at a desired setpoint. It typically employs a PID (Proportional-Integral-Derivative) control algorithm to achieve this. These controllers are widely used in several industrial applications to regulate temperature, pressure, flow, and other process variables.
Single oxide refractory – It is a type of refractory material mainly composed of a single oxide compound. Examples include alumina (Al2O3) and silica (SiO2). These refractories are characterized by their high temperature resistance and are normally used in industrial applications where high heat and load resistance are needed.
Single-phase bridge inverter – It is a type of direct current – alternating current inverter which converts direct current into alternating current using a bridge configuration, typically employed in renewable energy systems for efficient energy conversion.
Single-phase electric power – It is an alternating current power system using only two wires, where peak voltages in each wire occur at the same time.
Single phase motors – Single-phase motors are small motors, mostly built in the fractional kilowatt power rating range. These motors are used for several types of equipment in homes, offices, shops, and factories. They provide motive power for washing machines, fans, refrigerators, lawn mowers, hand tools, record players, blenders, juice makers, and so on. In fact, the number of single-phase (fractional kilowatt power rating) motors today far exceeds the number of integral kilowatt power motors of all types. Single-phase motors are relatively simple in construction. However, they are not always easy to analyze. Because of the large demand, the market is competitive, and designers use tricks to save production costs.
Single-phase rectifier – It is a circuit which converts alternating current to direct current using either line-commutated or controlled methods, with the latter using thyristors to enable control over the power conversion process.
Single-phase structure – It is also known as a homogeneous structure. It refers to a material where a single phase exists throughout, characterized by uniform physical and chemical properties. In single phase structure, the metal consists of only one type of crystallite. This means the material is not a mixture of different phases, like in a multiphase alloy, but rather shows a single, consistent structure.
Single-phase transformer – It is an electrical device which transfers electrical energy between circuits using electromagnetic induction, operating on a single-phase alternating current (AC). It consists of a primary winding connected to the alternating current supply and a secondary winding delivering power to the load. The two windings are wound around a common magnetic core, typically made of laminated silicon steel, which provides a path for the magnetic flux.
Single-phase distribution transformer – It is an electrical device which converts electrical energy from one single-phase alternating current circuit to another, either increasing or decreasing the voltage. It is normally used in power distribution systems to step down the high-voltage transmission lines to lower voltages suitable for residential and commercial applications.
Single point of failure (SPOF) – It is a part of a system which stops the entire system from working if it fails. The term single point of failure implies that there is not a backup or redundant option which enables the system to continue to function without it. Single point of failure is undesirable in any system with a goal of high availability or reliability, be it an operational practice, software application, or other industrial system. If there is a Single point of failure present in a system, it produces a potential interruption to the system which is substantially more disruptive than an error is elsewhere in the system.
Single-point tool – It is a cutting tool which is having one face and one continuous cutting edge.
Single pole double throw (SPDT) switch – It is a type of electrical switch with one input connection (the pole) and two output connections (the throws). It allows a person to switch a single circuit between two different output options. It can be thought as a switchboard operator, directing the flow of electricity between two separate paths
Single port nozzle – It is a constricting nozzle containing one orifice, located below and concentric with the electrode.
Single random variable model – It represents a situation where a single variable’s value is determined by the outcome of a random event. This variable, frequently denoted as ‘X’, assigns a numerical value to each possible outcome of the event. The model focuses on understanding the probability distribution of this single variable and its properties, like expected value and variance.
Single-shear test – It is a shear test similar to the double-shear test used for round-bar samples, but which uses only one stationary shear blade. It is also a shear test which uses a sheet or thin-plate sample.
Single-sideband modulation – It is a radio carrier modulation system where redundant frequencies of one duplicate side band are filtered out along with the carrier, to save transmitter power.
Single square groove weld – It is a type of groove weld.
Single-stage burner – It is a type of burner that operates at only one level of firing, meaning it is either fully on or completely off. This contrasts with multi-stage or modulating burners which can adjust their firing rate to different levels based on heating demands. It is a simple burner which operates at a single, fixed heat output, either ‘on’ at full capacity or ‘off’. It does not offer variable heat output like two-stage or modulating burners. Single-stage burners are typically used in applications where precise temperature or pressure control is not critical, and where a degree of temperature or pressure fluctuation is acceptable. These burners are typically used with natural gas or propane as fuel sources.
Single-stage centrifugal compressor – It is a device which combines one impeller with its associated inlet guide vane and diffuser, where velocity is converted into pressure within the diffuser and further increased as the gas passes through the volute.
Single-stage piston compressor – It is a type of air compressor where air is compressed from atmospheric pressure to a target pressure in a single piston stroke within a single cylinder. It works using the force of a piston and pressure sensitive valve. It is designed to house one cylinder which compresses air with a single piston stroke. This contrasts with multi-stage compressors, which use multiple cylinders and strokes to achieve higher pressures.
Single stage steam turbines – These are turbines which contain one Curtis stage. This includes two blade rows, and are designed to extract the maximum possible energy from steam to produce power.
Single-stand mill – It is a rolling mill which is designed such that the product contacts only two rolls at a given moment.
Single stroke open die heading machines – These machines are made for smaller-diameter parts of medium and long lengths and are limited to heading two diameters of the work piece because of their single stroke. Extruding cannot be done in this type of machine, but small fins or a point can be produced by pinching in the die, if desired. Similar machines are used to produce nails.
Single stroke solid die cold heading machines –These machines are made in diameters of around of 3 millimeters to 25 millimeters of the work piece which can be cold headed. Since these machines are single-stroke machines, product design is limited to less than two diameters of stock to form the head. Single-stroke extruding can also be done in this type of machine. These machines are used to make rivets, rollers and balls for bearings, single-extruded studs, and clevis pins.
Single U-groove weld – It is a type of groove weld.
Single-variable studies – It is the most common experiment conducted with several operations. Although several variables are identified as affecting the process, only one of these variables is changed at a time. Single-variable studies are widely used because they are easy to conduct and need a minimum number of experiments. First, one variable is changed, and then another, and so on, until all of the variables are at the second level.
Single vertical hitch configuration – It supports a load by a single vertical part or leg of the sling. The total weight of the load is carried by a single leg, the sling angle is 90-degree (sling angle is measured from the horizontal) and the weight of the load can equal the WLL (working load limit) of the sling and fittings. End fittings can vary but thimbles are to be used in the eyes. The single vertical hitch is not to be used for lifting loose material, lengthy material or anything difficult to balance. This hitch provides absolutely no control over the load since it permits rotation. The single vertical hitch is used on items equipped with lifting eyebolts or shackles.
Single V-groove weld – It is a type of groove weld.
Single welded joint – It is a fusion welded joint. In arc and gas welding, it is a joint welded from one side only.
Sink – It is a process, activity or mechanism which removes a green-house gas, an aerosol, or a precursor of a green-house gas or aerosol from the atmosphere is known as sink. Forests and other vegetation are
considered sinks since they remove carbon dioxide through photo-synthesis.
Sink-head – It is also called riser. It is a reservoir of molten metal connected to a casting to provide additional metal to the casting, needed as the result of shrinkage before and during solidification.
Sinking – It is the operation of machining the impression of a desired forging into die blocks. It is drawing tubing through a die or passing it through rolls without the use of an interior tool (such as a mandrel or plug) to control inside diameter. Sinking normally produces a tube of increased wall thickness and length.
Sink mark – It is a depression in the surface of a rubber part caused by (i) the collapse of blister or bubble, (ii) internal shrinkage in injection moulded parts, or (iii) shrinkage over rubber area in rigid sheet plastics. It is also a shallow depression or dimple on the surface of an injection-moulded part because of the collapsing of the surface following local internal shrinkage after the gate seals. It is an incipient short shot.
Sinter – It consists of fine particles of iron ore which have been treated by heat to produce blast furnace feed. Sinter is normally the major component of the iron bearing burden of the blast furnace. It normally consists of several mineral phases produced by sintering of iron ore fines with fluxes, metallurgical wastes, and a solid fuel. The chemical composition of the sinter needed for blast furnace depends upon the other components constituting the furnace burden. Normally the sinter ranges from fluxed (CaO/SiO2 around 1.2) to super-fluxed (CaO/SiO2 around 1.7 to 2.2) sinter.
Sinterability – It is the ability of a powder compact to undergo densification and grain growth during the sintering process, influenced by material variables such as powder composition, size, shape, and distribution, as well as process variables like temperature, time, atmosphere, and pressure.
Sinter cooler – It is a piece of equipment used to cool down the hot sinter produced in a sintering process, typically in iron ore processing. Sintering involves heating fine ore particles to fuse them into a porous, solid mass called sinter. The sinter cooler then reduces the sinter’s temperature, frequently using air, before it is used in other processes like blast furnaces. Two types of sinter coolers which are used are (i) straight line cooler, and (ii) annular cooler. Normally annular cooler is used for sinter cooling. In some sintering machines straight line coolers are also used.
Sinter crusher – It is used to break down the sinter product (a porous, lump-like material formed from iron ore fines and other materials) into smaller, more manageable sizes. Hot sinter crusher is installed after the sinter strand and is used to crush the hot sinter lump, while the cold sinter crusher is installed after sinter cooler for the sizing of the cold sinter to the sizes suitable for charging in the blast furnace.
Sintered aluminum powder – It refers to aluminum metal powder which has been heated to a temperature below its melting point, causing the particles to bind together and form a solid mass. This process, called sintering, creates a material with unique properties, including high strength, high creep resistance, and the ability to retain these properties at high temperatures.
Sintered density – It is the quotient of the mass (weight) over the volume of the sintered body expressed in grams per cubic centimeter.
Sintered density ratio – It is the ratio of the density of the sintered body to the solid pore free body of the same composition or theoretical density.
Sintered alloys – These are materials mainly used for highly stressed parts in applications such as automotive engines and transmissions, manufactured through powder metallurgy (PM) processes. Typical products include sprockets, gears, and bearing caps.
Sintered parts – These refer to components produced through the sintering process, which involves applying thermal energy to metal or ceramic powders to achieve density control and specific micro-structural characteristics. These parts are normally used in powder metallurgy and ceramics, emphasizing reproducible properties and controlled grain size and density.
Sintered property – It refers to the characteristics and physical attributes of a material which has been strengthened and densified through a sintering process, where powders are heated below their melting point to bond together, forming a solid object with controlled porosity, grain size, and mechanical strength. These properties are directly influenced by the sintering temperature, time, applied pressure, and the initial powder composition and micro-structure.
Sintering – It is the bonding of adjacent surfaces of particles in a mass of powder or a compact by heating. Sintering strengthens a powder mass and normally produces densification and, in powdered metals, recrystallization. Sintering is the bonding of powders by solid-state diffusion, resulting in the absence of a separate bonding phase. The process is normally accompanied by an increase in strength, ductility, and, occasionally, density. Sintering is also joining of particles and increasing their contact interfaces by atom movement within and between the particles because of the application of heat.
Sintering atmosphere – It is the surrounding protective environment in which a material is heated during the sintering process, which is a heat treatment process that densifies materials by bonding particles together without melting. The atmosphere plays a crucial role in controlling the oxidation, reducing potential, and overall quality of the sintered product.
Sintering cycle – It is a pre-determined and closely controlled time-temperature regime for sintering compacts, including the heating and cooling phases.
Sintering energy control system (SECOS) – It can detect and control the thermal energy level rapidly within an allowable range. Two parameters are considered by this control system namely (i) carbon quantity of the sinter mix which is burnt on the pallets (calculated through carbon balance by detecting the waste gas volume and composition), and (ii) hot zone ratio of the sinter cake cross section at the discharge end measured by a camera. Once evaluated the thermal energy level by using these two parameters, the coke blending ratio is adjusted. The implementation of this system has led to the Improvements in sinter quality and productivity.
Sintering machine – It is a continuous furnace-type device which transforms fine iron ore particles into a porous, larger-sized material called sinter, which is then used as a burden in blast furnaces. Sinter machines which are normally being used are straight line machines for large sinter plants and annular machines for small sinter plants. Exhaust gases are normally cleaned in cyclones and electrostatic separators before they are discharged to the atmosphere. In addition to all other demands, the design of a modern sinter plant with a strand type sinter machine is to meet the requirements of raw materials preparation and handling as well as product sizing and handling along with reasonably sophisticated controls and instrumentation. Sinter machine is the core of the sinter making technology and has the main components namely (i) pellet cars, (ii) drive for sinter strand, (iii) take-up mechanism, (iv) ignition furnace, and (v) crash deck and hot sinter crusher. In case of powder metallurgy, sintering machine is a type of furnace used to compact powdered materials into solid, dense objects. It achieves this by heating the powder, frequently below its melting point, which causes particles to bond together through solid-state diffusion and other mechanisms.
Sintering point – It is that temperature at which the moulding material begins to adhere to the casting, or in a test when the sand coheres to a platinum ribbon under controlled conditions. Also, it is the temperature at which sand grains begin to adhere to one another.
Sintering process – It is basically a pre-treatment process step during ironmaking which is used to agglomerate a mix of iron ore fines, return fines, fluxes, and coke breeze, with a particle size of less than 10 millimetres so that the resulting sinter, with a screened size of 5 millimetres to 30 millimetres, can withstand the pressure and the temperature conditions in the blast furnace. It is a metallurgical process carried out on a sintering machine. It is a thermal agglomeration process. The sintering process is an energy intensive process, in which a number of parameters have to be taken into account. The process is complex and involves various physical and chemical phenomena such as heat, mass, and momentum transfer coupled with chemical reactions. These phenomena take place simultaneously which increases considerably the complexity of the process. The complexity of sintering process results in the complexity of its control system.
Sintering technology – It is basically an agglomeration process for the iron ore fines which is dependent on heat to melt the surface of the smaller particles together to form larger agglomerates. A typical sinter plant consists of a number of sequential operating units with the sinter machine at the heart of the plant.
Sintering temperature – It refers to the maximum temperature at which a powder compact is heated to achieve densification and bonding of particles without melting the material. It is normally considered to be below the melting point of the material, typically between 60 % and 80 % of the melting temperature.
Sintering time – It refers to the duration a material, typically a powder compact, is heated below its melting point to achieve densification and bonding between particles. This process involves a thermal treatment where the compacted material is heated, causing atomic diffusion and leading to the formation of bonds between particles, ultimately resulting in a solid, stronger mass.
Sinter mix – The sinter mix which forms the sinter bed consists mainly of iron ore, coke breeze, fluxes and return fines. The behaviour of the sinter mix during sintering and the quality of sinter is dependent largely on the chemical, granulometric, and mineralogical composition of the iron ore. The ore characteristics impact the sintering behaviour and hence it is an important aspect in sinter production.
Sinter screens – These are a crucial component of a sintering plant used to separate and classify the material after the sintering process. They are specifically designed to sort sinter into different size fractions, with larger pieces suitable for blast furnaces and smaller pieces, frequently called return fines, being recycled back into the sinter mix. This ensures efficient operation of the blast furnace by providing a consistent feed of properly sized sinter. Hot sinter screen is installed after the hot crusher for screening of the unsintered materials, while cold screens are installed for the sorting of the cold sinter.
Sinter strand – It is a moving conveyor which transports sinter material through the sintering process, where iron ore fines and other materials are fused together at high temperatures to form a usable product for blast furnaces. Basically, it is the belt or track which carries the ‘sinter cake’ while it’s being processed.
Sinter strength – During transportation and charging of sinter into the blast furnace breakdown of the sinter must be minimized. This breakdown is related to its cold strength. Strength is of prime importance in assessing the sinter quality, and often it is the most important single index for sinter quality. Several tests have been developed for determining the strength. Virtually all the tests measure the strength of cold sinter. Hot strength of sinter is important but reliable testing method for the determination of hot strength is not available. The most common testing methods for assessing the strength of cold sinter may be grouped into three categories. These are drop or shatter test, impact test, and tumble test or abrasion test. The standard tests universally acceptable for the determination of sinter strength are as per the ISO (International Organization for Standardization) specifications.
Sintrate – It is the controlled heating so that a compact is sintered before the melting point of an infiltrating material is reached.
Sinusoidal oscillation – It is a periodic oscillation described mathematically by sine or cosine functions, characterized by key properties such as amplitude, frequency, and phase. It is normally observed in several natural phenomena, including seasonal variations in environmental contexts.
Sinusoidal pulse-width modulation (SPWM) – It is a switching technique for inverters which generates gate signals by comparing a sinusoidal reference voltage wave with a triangular carrier wave. It has a limitation in operation above a modulation index (M) of 0.786, affecting the efficient utilization of the direct current-link voltage.
Sinusoidal waveform – It can be expressed mathematically using the sine function and shows a characteristic smooth, periodic oscillation. It is the normally known and used periodic wave in electrical and electronic engineering field. It can be defined in terms of the sine trigonometric function. A Sine wave starts from zero value and covers positive values reaching to zero again and then covers negative values until reaching to zero. This is called one cycle of the wave. The upper part of sine wave is called positive cycle and the lower part is called negative cycle in a single cycle.
Siphon – It is also spelled syphon. It is any of a wide variety of devices that involve the flow of liquids through tubes. In a narrower sense, the word refers particularly to a tube in an inverted ‘U’ shape, which causes a liquid to flow upward, above the surface of a reservoir, with no pump, but powered by the fall of the liquid as it flows down the tube under the pull of gravity, then discharging at a level lower than the surface of the reservoir from which it came. There are two leading theories about how siphons cause liquid to flow uphill, against gravity, without being pumped, and powered only by gravity. The traditional theory for centuries was that gravity pulling the liquid down on the exit side of the siphon resulted in reduced pressure at the top of the siphon. Then atmospheric pressure was able to push the liquid from the upper reservoir, up into the reduced pressure at the top of the siphon, like in a barometer or drinking straw, and then over. However, it has been demonstrated that siphons can operate in a vacuum and to heights exceeding the barometric height of the liquid.
Siphon fountain – It is a type of fountain that utilizes a siphon to draw water from a source, typically a reservoir, and propel it upwards, creating a display. The siphon mechanism relies on gravity and the pressure difference created by the flow of liquid through a U-shaped tube.
Site elevation – It is the designated height of a site above sea level, which is important for several engineering calculations, including foundation depth and hydraulic design.
Site layout – It is the careful planning of site working areas to ensure optimal and effective use of materials and equipment, including the establishment of designated areas for operations and the sorting of leftovers for future use.
Site plan drawing – A site plan is a location drawing, and like most plans is a view looking downwards. It supplies a bird’s eye view of the shape, size and layout of the entire site. The site plan is a large-scale map of the plant site and reveals boundaries, roads, railroad, pavement, building outlines, large structures, production shop area, major pipe racks, storage areas, waste effluent ponds, large underground pipes, and disposal, shipping and loading areas. True north and assumed plant north is shown on the site plan. The plant personnel use this plan to decide where the production shops are to be located. The site plan is frequently divided into smaller units which are numbered. These are sometimes called key or index plans and are defined by match (boundary) lines. The unit plot plan is developed from the site plan. It reveals the equipment foundation outlines, structural foundation outlines, and structural members in a unit. Coordinates for centre-lines of equipment are indicated, except for pumps where the pump shaft centre-line is used as reference.
Site preparation – It involves clearing and preparing the land for building by removing obstructions, grading the soil, and establishing necessary infrastructure like drainage. It is a crucial initial phase which sets the stage for a safe and successful construction project by ensuring the site is stable, suitable, and ready for the intended building or development.
site selection process is a strategic and analytical method for identifying, evaluating, and choosing the most suitable physical location for a new business facility, retail store, or expansion. It involves a team that researches a location’s financial, demographic, and geographic data, assessing potential sites based on established criteria like infrastructure, market access, labor availability, and costs to ensure the chosen site maximizes operational efficiency and long-term success.
Site selection process – It is a strategic and analytical method for identifying, evaluating, and choosing the most suitable physical location for a new facility, or expansion. It normally involves two phases consisting of (i) site screening which consists of the identification of a few numbers of likely sites best suiting the selection criteria and (ii) detailed examination of each short listed site to decide the most suitable site. The selection process includes the determination of the most suitable selection criteria, collection of the data for the short-listed sites with respect to the selected criteria, and analysis and the evaluation of the collected data with the objective of finding the most suitable site. The factors which are contributing to the complexity of the site selection process include (i) possibility of a large number of potential sites which can be available satisfying the selection criteria to varying degree, (ii) there can be possibility of contradictions in some of the objectives e.g. the objective of keeping minimum capital investment can contradict with the objective of keeping a long term safe environment, (iii) intangible objectives meaning those objectives which cannot be quantified, (iv) diversity of Interest groups which means that investment decision at a particular site can impact several public groups who can have diversity of interest and as such these groups who are not satisfied with the investment decision can create problems for the plant, and (v) decisions regarding value tradeoffs especially amongst the multiple contradicting objectives can be challenged and are to be faced during the site selection process.
Site-specific approach – It involves tailoring designs and construction methods to the unique characteristics and conditions of a particular location. This includes factors like soil conditions, geology, topography, climate, and local regulations. By considering these site-specific elements, engineers can optimize design, minimize risks, and ensure the long-term performance and sustainability of structures.
Six-high levellers – These levellers have two additional rows of straight solid intermediate rolls between work rolls and adjustable backup rolls, each at the top and bottom frames. This arrangement prevents marking on the top and bottom surfaces of the strip but limits the capability to correct poor shape since the adjustable roll flights act on the intermediate rolls.
Six-high mill roll configuration – In this type of roll configuration, there are six horizontal rolls, mounted in a single vertical plane. Two rolls (inner) are work rolls and four rolls are back-up rolls. This configuration is normally used in cold rolling of steel strip.
Six-high mill stand – Six-high mill stand has three rolls on either side of the work piece bar. The intermediate roll allows for a reduction of the work roll diameter further than can be achieved with the four-high mill, since the ratio of two adjacent roll diameters are kept low. The intermediate roll can be equipped with a side-shift mechanism with which the rolls can be moved laterally in and out over the strip edge during rolling. Six-high mill stand eliminates most of the roll bending at the edges by lateral movement of the intermediate rolls to let the edge coincide with the edge of the work piece.
Six sigma – It is a data-driven methodology used to identify and eliminate defects in processes, leading to near-perfect quality and efficiency. Total quality management (TQM) encompasses a broader philosophy of continuous improvement across all aspects of an organization, while six sigma provides specific tools and techniques to achieve significant process improvements.
SI units – International System of Units, internationally known by the abbreviation SI (from French Système international d’unités), is the modern form of the metric system and the world’s most widely used system of measurement. It is the only system of measurement with official status in nearly every country in the world, employed in science, technology, industry, and everyday commerce. The SI system is coordinated by the International Bureau of Weights and Measures, which is abbreviated BIPM from French: Bureau international des poids et mesures. The SI comprises a coherent system of units of measurement starting with seven base units (Table 1), which are the second (symbol s, the unit of time), metre (m, length), kilogram (kg, mass), ampere (A, electric current), kelvin (K, thermodynamic temperature), mole (mol, quantity of substance), and candela (cd, luminous intensity).
| Table 1 The seven SI base units | ||
| Symbol | Name | Quantity |
| s | second | Time |
| m | metre | Length |
| kg | kilogram | Mass |
| A | ampere | Electric current |
| K | kelvin | Thermodynamic temperature |
| mol | mole | Quantity of substance |
| cd | candela | Luminous intensity |
he system can accommodate coherent units for an unlimited number of additional quantities. These are called coherent derived units, which can always be represented as products of powers of the base units. Twenty-two coherent derived units have been provided with special names and symbols. The seven base units and the 22 coherent derived units with special names and symbols can be used in combination to express other coherent derived units.
Size – Size in general is the magnitude or dimensions of a thing. More specifically, geometrical size (or spatial size) can refer to three geometrical measures namely length, area, or volume. Length can be generalized to other linear dimensions (width, height, diameter, or perimeter). Size can also be measured in terms of mass, especially when assuming a density range. In composites manufacturing, size is a treatment consisting of starch, gelatin, oil, wax, or other suitable ingredients applied to yarn or fibres at the time of formation to protect the surface and aid the process of handling and fabrication or to control the fibre characteristics. The treatment contains ingredients which provide surface lubricity and binding action, but unlike a finish, contains no coupling agent. Before final fabrication into a composite, the size is normally removed by heat cleaning, and a finish is applied.
Size consistency, sinter – Consistency in sinter size has a significant effect on blast furnace performance. There is no universally recognized optimum sinter size, but it is normally accepted that fines are detrimental to furnace operation. Fine material lowers blast furnace stack permeability, increases dust losses, and can lower the maximum permissible blast temperature for smooth furnace operation. Sinter which is too coarse is also undesirable, particularly if its reducibility is low and it is poor in strength, hence undergoing physical degradation during furnace processing.
Size control – It normally refers to the process of managing and regulating the dimensions or quantities of something to meet specific requirements or standards. This can apply to several fields, including manufacturing, garment sizing, industrial processes, and even population management. Size control is done (i) to prevent undersize in the feed from blocking the next size reduction stage (scalping), (ii) to prevent oversize from moving into the next size reduction or operation stage (circuit sizing), and (iii) to prepare a sized product (product sizing). There are two methods dominating size control processes. They are (i) screening using a geometrical pattern for size control, and (ii) classification using particle motion for size control.
Size distribution – It refers to the statistical characterization of particle sizes within a sample or material. It describes the frequency of particles of a certain size and is a crucial aspect of material properties and quality control. Size distribution of particles in a granular bulk material is the primary characteristic which governs the rate of undersize passage through a screen opening that is larger than the smallest particle and smaller than the largest particle in a representative sample of the material. Size distribution is measured by sieve analysis, using a series of standardized wire mesh sieves with square openings. International Organization for Standardization (ISO) provides specific methods and guidelines for determining and characterizing size distribution, particularly in areas like powders, soils, and aerosols.
Size effect – It is the effect of the dimensions of a piece of metal on its mechanical and other properties and on manufacturing variables such as forging reduction and heat treatment. In general, the mechanical properties are lower for a larger size.
Size-exclusion chromatography (SEC) – It is the liquid chromatography method which separates molecules on the basis of their physical size. This technique is very frequently used in the analysis of polymers. It is also termed gel-permeation chromatography.
Size fraction – It refers to a grouping of particles within a material which fall within a specific size range. These ranges are frequently defined using sieves or other particle size analysis methods. The average particle size within a fraction is typically calculated by averaging the upper and lower size limits of that fraction.
Size reduction – It refers to the process of breaking down large solid materials into smaller particles through mechanical means like crushing, grinding, or milling. This process is also called comminution.
Sizing – It consists of secondary forming or squeezing operations needed to square up, set down, flatten, or otherwise correct surfaces to produce specified dimensions and tolerances. It also means some burnishing, broaching, drawing, and shaving operations. Sizing is also a finishing operation for correcting ovality in tubing. It is also final pressing of a sintered powder metallurgy part to get a desired dimension. In foundry, sizing is a primary coating of glue applied to the end grain of wood to seal the pores.
Sizing content – It is the percent of the total strand weight made up by the sizing. It is normally determined by burning off or dissolving the organic sizing, known as loss on ignition
Sizing design parameter – It is a design parameter which does not alter the location of nodes in a numerical (finite element method, FEM) model of the design. Examples are material properties and boundary conditions.
Sizing die – It is a specific tooling which is used in a process called sizing. Sizing is a post-sintering operation which involves repressing a powder metallurgy part to achieve tighter dimensional tolerances. Essentially, the die is a mould with a precise shape and size which is used to compress the sintered part, ensuring it meets the needed specifications.
Sizing knock-out – It is an ejector punch which is used for ejecting a sintered compact from thr sizing die.
Sizing punch – It refers to punch with specific shape and size designed to mould powder or granules into the desired shape and form. The punch is crucial for ensuring uniform weight, thickness, and hardness, impacting compact quality and consistency.
Sizing stripper – It refers to a tool or process used to remove excess material from a powder-based product, ensuring it meets specific dimensional tolerances. This is frequently done to create a final product with precise dimensions or to remove material after a process like powder compaction.
Skarn – It is the name for the metamorphic rocks surrounding an igneous intrusive where it comes in contact with a limestone or dolostone formation.
Skein – It is a continuous filament, strand, yarn, or roving, wound up to some measurable length and normally used to measure several physical properties.
Skeletal formula – It is also called line-angle formula, bond-line formula or shorthand formula of an organic compound is a type of minimalist structural formula representing a molecule’s atoms, bonds and some details of its geometry. The lines in a skeletal formula represent bonds between carbon atoms, unless labelled with another element. Labels are optional for carbon atoms, and the hydrogen atoms attached to them.
Skeleton – It is an unsintered or sintered porous compact with a large proportion of interconnected porosity which makes it suitable for infiltration.
Skeleton pattern – It is a framework representing both the exterior and interior of the shape of the casting.
Skelp – It is the starting stock for making welded pipe or tubing. Very frequently it is strip stock of suitable width, thickness, and edge configuration.
Skelp mills – These mills hot roll narrow strips in the form of coils. Narrow strips are used for the production of welded pipes.
Skeletal box plot – It is a simplified version of a box plot that primarily focuses on displaying the five-number summary of a dataset: the minimum, first quartile (Q1), median, third quartile (Q3), and maximum. It is characterized by a box representing the interquartile range (IQR) (the space between Q1 and Q3) with a line within the box marking the median, and whiskers extending from the box to the minimum and maximum values. The skeletal boxplot can be expanded to include more information about extreme values in the tails of the distribution. For doing so, people need the following additional quantities namely (i) lower inner fence, Q1 – 1.5(IQR), upper inner fence, Q3 + 1.5(IQR), lower outer fence, Q1 – 3(IQR), and upper outer fence, Q3 + 3(IQR). Any score beyond an inner fence on either side is called a mild outlier, and a score beyond an outer fence on either side is called an extreme outlier.
Sketch – It is a rough, preliminary drawing or plan, frequently created quickly free hand and without much detail, to explore ideas or form a basis for a more finished piece. It is a way to capture the main features of a subject or design before committing to a more detailed or finalized representation.
Skew – If the distribution (or ‘shape’) of a variable is not symmetrical about the median or the mean it is said to be skew. The distribution has positive skewness if the tail of high values is longer than the tail of low values, and negative skewness if the reverse is true.
Skew angle – It is the degree of misalignment or tilt between two objects or lines, representing the angular deviation from a perpendicular or aligned position. It is frequently used in fields like structural engineering, geometry, and optics to describe the angle at which one component is not at a right angle to another, such as the skew of a bridge support relative to the bridge’s centerline or the angle of a wave’s propagation compared to its energy velocity.
Skew-back – It is a sloping surface or a stone or brick course which provides a sloping surface for the arch to rest against. It essentially acts as a transition between the horizontal plane of the supporting structure (like an abutment) and the inclined plane of the arch.
Skewness – Skewness is the lack of symmetry in a probability distribution. In a skewed distribution the mean and median are not coincident.
Skew rays – These are light rays which travel through an optical system, like a lens or optical fibre, without passing through the central axis (also known as the optical axis or meridional plane). Unlike meridional rays which lie in a plane containing the optical axis, skew rays travel at an angle to this plane, frequently spiraling around the axis as they propagate.
Skew rolling – It is a metal forming process where metal is deformed by passing it through specially designed rollers, frequently used to produce ball bearings or stepped shafts. The key characteristic is the angle or skew between the roller axis and the work-piece axis, creating a non-uniform deformation.
Skew rolling mills – Skew rolling mills are used for the production steel balls for ball bearing. The semi-finished balls made by the skew rolling process are subsequently ground and polished for use in ball bearings.
Skid – It refers to a system of heated or cooled metal beams or pipes which support and move steel slabs, blooms, or billets as they are heated to the desired temperature in a reheating furnace for rolling. These skids are crucial for efficient and controlled heating, and they can be found in several types of reheating furnaces, including those using walking beams. In case of vehicles, skid is for a vehicle’s tyres to lose grip on the road surface, causing the vehicle to slide uncontrollably sideways or in a way not intended by the steering. This loss of traction can happen from sudden braking, acceleration, or steering, particularly on surfaces with reduced friction, such as wet or icy roads.
Skid control – It refers to the electronic intervention systems, such as acceleration skid control (ASR), which prevent drive wheels from slipping by regulating engine power output and applying brakes as necessary, hence improving vehicle stability and safety.
Skidding – It is a form of non-uniform relative motion between solid surfaces because of rapid periodic changes in the traction between those surfaces.
Skid-polishing process – It is a mechanical polishing process in which the surface of the metallographic sample to be polished is made to skid across a layer of paste, consisting of the abrasive and the polishing fluid, without contacting the fibres of the polishing cloth.
Skill – It is the capacity to perform an observable action. It is the learned or innate ability to act with determined.
Skim – In a conveyor belt it refers to the layer of rubber, poly-vinyl chloride (PVC), or urethane which is placed between the plies of the belt carcass. These skims play a crucial role in adhesion, impact resistance, and the overall load support and trough ability of the belt. Improper or marginal skims can lead to issues like ply separation and idler junction failure, impacting the belt’s performance.
Skim bob – It is a small upward bulge in the grating system, near the casting cavity, which functions as a dirt trap.
Skim coat – It is a layer compound laid on a fabric but not forced into the weave. It can be spread or calendered.
Skim core – It is a flat core or tile placed in a mould to skim a flowing stream of metal. It is normally used in pouring basins. It holds back the slag and dirt while clean metal passes underneath to the down-sprue.
Skim gate – In foundry practice, it is a gating arrangement which changes the direction of flow of molten metal and prevents the passage of slag and other undesirable materials into the mold cavity. It is a gating arrangement which is designed to prevent the passage of slag and other undesirable materials into a casting.
Skimmer – It is a device or a tool for removing slag and dross from the surface of molten metal. It is a block of refractory which is set across and into the trough. The skimmer has a small opening underneath it. The hot metal flows through this skimmer opening, over the ‘iron dam’, and down the ‘iron runner’. Since the slag is less dense than iron, it floats on top of the iron, down the trough, hits the skimmer and is diverted into the slag runners.
Skimming – It is removing or holding back dirt or slag from the surface of the molten metal before or during pouring. It is also a galvanizing by-product which is comprised mainly of zinc oxides. The skimming is recyclable.
Skimmings Inclusions – Skimmings are deposits of zinc oxide and zinc chloride which form on the surface of the molten zinc bath and can become trapped on the galvanized coating, appearing as black or gray powdery inclusions. These skimmings inclusions occur when the oxides are not properly removed from the bath’s surface before or during the withdrawal of the steel part, resulting in deposits which, despite not typically harming the underlying corrosion protection, are frequently a cosmetic defect customers do not accept.
Skin – It is a thin outside metal layer, not formed by bonding as in cladding or electroplating, which differs in composition, structure, or other characteristics from the main mass of metal. It is also the relatively dense material which can form the surface of a cellular plastic or of a sandwich. In case of rubber, skin is (i) a dense layer on the surface of cellular material, or (ii) an overcured layer on the surface of a moulded rubber part.
Skin burn injury – It refers to the damage caused to skin tissue when the temperature exceeds 44 deg C, with severity classified into degrees based on the depth of damage namely (i) first-degree affects the epidermis, (ii) second-degree involves both the epidermis and dermis, and (iii) third-degree penetrates the entire skin layer. The assessment of burn severity is quantified using a burn injury integral, which accounts for temperature exposure time and tissue response.
Skin drying – It is the drying the surface of the mould by direct application of heat.
Skin effect – It is the tendency of alternating current to flow at the periphery of a conductor. It is significant for large conductors at power frequencies, and increasingly significant as the frequency increases.
Skin lamination – In flat-rolled metals, It is a surface rupture resulting from the exposure of a subsurface lamination by rolling.
Skin milling – It consists of grinding of the top and / or bottom of a large aluminum plate into close tolerance.
Skinning – It is the formation of a thin, tough film on the surface of a liquid paint film, normally because of the reaction with the air or to rapid solvent loss.
Skin pass rolling – It is also called temper rolling. It is light cold rolling of sheet steel. Cold-rolled coils after removed from the annealing furnace are in their dead soft condition and are hence to undergo a skin pass rolling in a skin pass mill. This involves a controlled light reduction of the cold rolled steel sheet and is carried out because of many reasons such as (i) to improve steel sheet flatness, (ii) to minimize stretching of steel, (iii) to minimize straining, (iv) to cause the unsteady yield-point range, known as the Luders band, transformed into a defined yield point, (v) to get desired steel surface texture, and desired roughness of the strip surface, (vi) to get desired mechanical properties, (vii) to get a specified hardness or temper, and (viii) to correct gauge inconsistencies in steel. Skin pass rolling imparts a small quantity of cold reduction, typically in the range of 0.2 % to 3 %. Temper rolling results in a surface which is smooth and the yield point phenomenon (excessive stretching and wrinkling in subsequent operations) is eliminated. This makes the steel more ductile for further forming and stretching operations.
Skin pass mill – It is also known as a temper mill. It is a type of rolling mill used in cold rolling mills, particularly in the production of steel, to improve the surface finish, flatness, and mechanical properties of metal strips. It is typically the final rolling stage before the material is shipped or further processed in processing lines. Skin pass mills achieve this by applying a small reduction (typically 0.2 % to 3 % elongation) to the strip, which refines the surface texture and improves flatness, while also influencing other properties like yield strength. A single skin pass mill is independent rolling facility which normally follows the batch annealing stage and can be implemented very flexibly. This mill can process both hard strip and ultra mild strip. It also provides the perfect finish for cold rolled steel strip. A special case is represented by what is known as the double cold reduction (DCR) rolling mill. This two-stand rolling mill combines thickness reduction in the first stand with skin passing in the second stand. It is also possible to use both stands for skin passing. In this case the steel properties, such as a defined yield point, are set in the first stand while in the second stand, the desired surface characteristics are transferred to the strip. Skin pass mills can also be installed directly in line in the exit section of a continuous annealing line. The strip can be completed in the process line and this has several advantages since the efforts and expenditure on coil handling is reduced substantially.
Skip – It is a self-dumping bucket used in a shaft for hoisting ore or rock. In blast furnace, skip is a special shape bucket for carrying the charge material to furnace top from the stock house. Normally there are two skips in each furnace. One skip goes up while the other comes down. Skip also means an area of uncoated sheet frequently caused by equipment malfunction.
Skip hoist – It is the hoisting mechanism for taking the skip from the stock house to the blast furnace top.
Skip welding – It is alternating the weld so that it is not continuous or complete.
Skirt – In pressure vessels, it is a cylindrical support structure attached to the bottom of the vessel. It supports mainly the vessel’s weight and the weight of the fluid inside, as well as environmental loads like wind and seismic forces. The skirt does not typically bear the pressure from the fluid itself. In a basic Oxygen furnace (BOF), a skirt is a piece of equipment which is lowered over the furnace mouth during the oxygen blowing process to reduce air infiltration and control the combustion of carbon mono-oxide (CO). This helps recover and clean carbon mono-oxide-rich gas for use as fuel in the steel plant. In composites, skirt is the extension of a motor-case from the tangency plane, used for inter-stage connections, normally wound or laid up as an integral part of the case.
Skirt board – In a conveyor system, it is the vertical or inclined plates located longitudinally and closely above the belt to confine the conveyed material.
Skive – It is a 45-degree bevel in top and / or bottom cover across the belt width in a splice.
Skiving – It is the removal of a material in thin layers or chips with a high degree of shear or slippage, or both, of the cutting tool. It is a machining operation in which the cut is made with a form tool with its face so angled that the cutting edge progresses from one end of the work to the other as the tool feeds tangentially past the rotating work-piece.
Skull – It is a layer of solidified metal or dross on the walls of a pouring vessel after the metal has been poured. It is the unmelted residue from a liquated weld filler metal.
Skyscraper – It is a tall continuously habitable building having multiple floors. Majority of the modern sources define skyscrapers as being at least 100 metres or 150 metres in height, though there is no universally accepted definition, other than being very tall high-rise buildings. One common feature of skyscrapers is having a steel frame which supports curtain walls. These curtain walls either bear on the framework below or are suspended from the framework above, rather than resting on load-bearing walls of conventional construction. Some early skyscrapers have a steel frame which enables the construction of load-bearing walls taller than of those made of reinforced concrete.
Slab – It is a flat-shaped semi-finished rolled metal ingot with a width not less than 250 millimeters and a cross-sectional area not less than 105 square centimeters. It also means a thick, flat, frequently rectangular piece of a solid material like stone, wood, or concrete. In construction, a concrete slab is a flat, horizontal structural element which forms floors, ceilings, or roofs, providing support for walls, columns, and beams.
Slab belting – It is the belting made in wide widths and long lengths for later slitting into narrower widths and cutting into shorter lengths.
Slab core – It refers to the internal, hollow, or voided section within a hollow-core slab, a precast concrete structural element with continuous longitudinal voids which reduce its weight and material usage while maintaining structural integrity. These hollow spaces, frequently circular or oval, run the length of the slab and can also serve as conduits for electrical wiring or ventilation systems. The main purpose of the slab core is to reduce the overall weight of the concrete slab, making it lighter, easier to handle, and transport to the construction site. In foundry, slab core is a plain flat core.
Slabbing – It is the hot working of an ingot into a flat rectangular shape.
Slabbing mill – It is a primary mill which roll ingots to produce slabs.
Slab milling – The preferred term peripheral milling. It consists of milling a surface parallel to the axis of the cutter.
Slab sizing press – Modern hot strip mills are equipped with a sizing press in place of an edger. A slab sizing press in the roughing mill area has the technological advantage over a conventional edger. Besides large width reductions (up to 350 millimeters), it results into a distinctly better through forming of the slab right to its centre. Slab sizing press produces flatter dog bones leading to reduced respreading and greater sizing efficiency. It offers more flexibility in production. Slab sizing press improves width tolerance along the entire strip. The sizing press offers distinct advantage of far more flexibility in the hot strip production. The width reduction in the sizing press pass enables the number of sizes in the continuous casting to be standardized to a few widths which in turn helps in the enhancement of the productivity in continuous casting machine. A special short stroke mode at the slab head and tail ends results into less cropping losses and higher yield.
Slab thickness – It is the vertical depth or dimension of the slab. In case of a concrete or composite slab, the value of slab thickness is critical for structural integrity, influencing strength, deflection, and load-carrying capacity. Thickness is determined by the slab’s specific application and intended use, including factors like span length, expected loads, and structural design requirements determined by qualified engineers. Factors such as the aggregate size, the type of reinforcement, and the concrete mix grade also play a role in defining the appropriate minimum thickness for a safe and efficient structure.
Slack – It refers to the very small pieces and dust resulting from coal mining or processing. It is essentially the fine screenings which are not usable as fuel unless cleaned. Slack coal is frequently characterized as bituminous coal with a size of 10 millimeters or smaller.
Slack quenching – It is the incomplete hardening of steel because of the quenching from the austenitizing temperature at a rate slower than the critical cooling rate for the particular steel, resulting in the formation of one or more transformation products in addition to martensite.
Slag – It is an ionic solution consisting of molten metal oxides and fluorides which float on top of the steel (completely liquid or partially liquid). It is the vitreous mass separated from the fused metals in the smelting process. It consists of a non-metallic product consisting essentially of silicates and alumino-silicates of calcium and other bases which is produced in a molten condition and resulting from the mutual dissolution of flux and non-metallic impurities in smelting, refining, and certain welding operations (e.g., electroslag welding). In steelmaking operations, the slag serves to protect the molten metal from the air and to extract certain impurities. Slag is a non-metallic material formed during refining of metal, as a by-product of a high temperature process, or resulting from chemical reaction between refractory and its service environment. Slags can be classified as (i) crusty, (ii) fluffy, (iii) creamy, and (iv) watery. Crusty slag has too much calcium oxide (and / or magnesium oxide). Fluffy slag is calcium oxide / magnesium oxide saturated, and is satisfactory for refractories but not optimum for desulphurization. Creamy slag is just calcium oxide / magnesium oxide saturated, is good for steelmaking and refractories (ideal). Watery slag is too liquid, aggressive to the refractories. A partially liquid slag consists of a liquid fraction and a solid fraction. As the solid fraction of the slag increases the fluidity of the slag decreases and it changes from ‘creamy’ to ‘fluffy’, and eventually to ‘crusty’ or solid.
Slag aggregate – It is a synthetic aggregate got by crushing smelter slag or through the special treatment of molten slag, which is used in concrete and construction as a binding component and filler. It is produced by altering the physical and chemical properties of metallurgical by-products, such as blast furnace slag.
Slag bond – It is also called fusion bond. It consists of partial or complete embedding of crystalline constituents in the matrix of a fused glassy melt, the extent depending upon the volume and wettability of the liquid phase. The bond strength depends upon the amount of glass and the quantities and types of the constituents. These depend upon the fuel rate and impurities silica (SiO2), calcium per-oxide (CaO2), lime (CaO), magnesia (MgO), and alumina (Al2O3), added or present.
Slag cement – It is a cementitious material produced by grinding blast furnace slag into a fine powder. It is used as a supplementary cementitious material, frequently replacing Portland a portion of cement in concrete mixes, to improve durability, strength, and other properties.
Slag composition measurement – Analysis of the slag composition evolution before and after operations can be interpreted to estimate inclusion absorption to the slag. Also, slag entrainment from a particular vessel can be determined by matching trace elements in the slag and inclusion compositions.
Slag conditioning – It refers to the process of modifying the properties of slag to assist steel refining and to improve its performance and suitability for several applications. This is achieved by adding specific materials, like magnesium, carbon, or fillers, and binders, to control factors like viscosity, saturation, and reactivity, ultimately impacting things like refractory wear, slag foaming, and energy efficiency in steelmaking furnaces.
Slag engineering – It is also known as slag balancing. It is defined as the balance between the refractory oxides and the fluxing oxides. This balance is typically expressed as a basicity ratio. Basicity ratio is the ratio of the refractory oxides and fluxing oxides [(% calcium oxide + % magnesium oxide)/(% silicon oxide + % aluminum oxide + % calcium fluoride + % ferrous oxide)].
Slag foam – It is formed when the gases injected and generated by the refining reactions are trapped by the slag during the process. For slag foams, the quantity of gas trapped by the slag is measured by the void formation (VF) or the gas fraction, and the void formation normally varies in the range of 0.7 to 0.9. The combined effect of evolving physical properties of slag during the blow is to be in favour of foam stabilization, and when coincided with the high rate of decarburization in the first half of the blow, the volume of the slag foam increases rapidly. Slag foaming is beneficial as it assists the refining process in many ways, for example, by providing an increased surface area for refining reactions, protecting the molten metal bath from the direct contact of the atmosphere, protecting the refractory lining from extreme combustion effects, and forming the medium for post-combustion and heat transfer. On the other hand, slag foaming can become disadvantageous and hazardous when formed in huge quantities, and overflow from the mouth of the converter.
Slag fluidity – It refers to the ease with which a liquid slag flows at a given temperature and composition. It is a crucial property in several metallurgical processes, directly impacting the efficiency and stability of operations. Fluidity is influenced by factors like slag composition, temperature, and the presence of certain elements, particularly those that act as network modifiers.
Slag forming – It is a complicated process which depends on several factors such as the quality of materials used and the selected process. Slag with determined properties is achieved because of the use of an appropriate quantity of slag forming materials during the secondary steelmaking process. It is also necessary to use of good quality materials. These materials in combination with the products of oxidation of iron, admixtures together with impurities form slag.
Slag granulation – It is the process of cooling molten slag (a by-product of metal smelting) into granular form, either by using water or air. This process can be done wet or dry, and the resulting granules can be used as a cement substitute or in other industrial applications.
Slag granulation plant – In slag granulation plant, liquid slag is granulated by quenching it with high pressure water jet. It is normally situated by the side of the blast furnace cast house.
Slag inclusion – It is the slag or dross entrapped in a metal. It is also non-metallic solid material entrapped in weld metal or between weld metal and base metal. In foundry, it is the casting surface imperfections similar to sand inclusions, but containing impurities from the charge materials, silica and clay eroded from the refractory lining, ash from the fuel during the melting process. It can also originate from metal-refractory reactions occurring in the ladle during pouring of the casting.
Slagging of refractories – It is the destructive chemical reaction between refractories and external agencies at high temperatures resulting in the formation of a liquid.
Slag metal reactions – These reactions refer to the processes in metallurgical refining where elements in the slag phase interact with metals, facilitating the removal of impurities or additives through different oxidation or reduction reactions. These reactions are influenced by the basicity of the slag, which affects the distribution of elements between the slag and metal phases.
Slag notch – It is also known as cinder notch. All the blast furnaces do not have this notch. The slag notch is used for tapping slag from the furnace.
Slag phase – It refers to the poorly crystalline phases present in metallurgical slags, which include compositions resembling gehlenite and akermanite, and are characterized by a calcium aluminosilicate framework. In sinter, slag phase is mainly a silicate glass (combinations of FeO, CaO, Al2O3 and SiO2), but contains fayalite (2FeO.SiO2), wollastonite (CaO.SiO2), iron monticellite (CaO.FeO.SiO2) and anorthite (CaO.Al2O3.2SiO2). The reactivity of slag phases is influenced by factors such as particle size and the specific network structures formed during the alkali activation processes.
Slag separation – It is the process of separating molten or solid slag from molten metal or waste streams during metallurgical and refining processes, or separating components within the slag itself. This separation is necessary for recycling valuable materials like iron from steelmaking slag, improving the quality of the molten metal by removing impurities, and managing waste products. Methods vary from physical tilting and inductive troughs for molten slag to crushing, sieving, and magnetic separation for solid slag.
Slag splashing technology – It consists in the splashing of the left-over slag from previous heat by blowing of nitrogen gas on it towards the hot face of the converter through a blowing lance. It consists of coating the slag on the converter lining by freezing the liquid slag on the walls of the converter. The nitrogen supply parameters namely pressure and flow rate, general slag condition and consistency of operation are the three major factors for the success of slag splashing. A higher superheat of the slag (difference between tapping temperature and the liquidus temperature of the final slag) results into thinner slag and faster melt back of the protective slag layer. Hence, reasonable steel tapping temperature and reasonable control of the converter slag are the keys to success of the slag splashing. As the interaction between the slag and the nitrogen occurs, the slag temperature is gradually reduced, which substantially impacts the phase distribution and, consequently, the effective viscosity of the slag. Basic principle of lining protection by slag splashing technology is based on the adjustment of the slag viscosity. Good slag splashing needs composition adjustment of end slag with respect to iron oxide (FeO) and magnesium oxide (MgO) concentration and basicity.
Slag spots defect -This defect is caused by the penetration of tundish slag in the cast product. It is caused by high level of slag in the tundish, rise in the active oxygen percentage in the steel, lowering of steel level in the tundish resulting in slag to enter the mould, and high viscosity of casting powder.
Slag trap – It is an enlargement, dam or protrusion in the gating or runner system in a mould for the purpose of preventing molten slag particles from entering the mould cavity.
Slag viscosity – It is a measure of molten slag’s resistance to flow, a crucial property in metallurgical processes for controlling operations, optimizing mass transfer, and understanding slag-metal interactions. It indicates the internal friction within the slag and is influenced by its composition, temperature, and structure, with basic oxides normally decreasing viscosity by breaking down the silicate network.
Slag volume – It refers to the amount or space occupied by slag in a smelting furnace. Slag volume can vary significantly depending on factors like the raw materials used, the type of furnace, and the smelting process (e.g., ironmaking, steelmaking).
Slant fracture – It is a type of fracture in metals, typical of plane-stress fractures, in which the plane of separation is inclined at an angle (normally around 45-degree) to the axis of applied stress.
Slash – It is the process of blasting rock from the side of an underground opening to widen the opening.
Slate – It is a metamorphic rock. It is the metamorphic equivalent of shale.
Slave architecture – It refers to a configuration in a master / slave system where multiple slave units operate under the control of a master unit, allowing for increased output capacity, such as in a direct current / direct current converter setup which combines the output current of multiple slaves with a master.
Sledge hammer – It is a large, heavy hammer with a long handle, used for breaking stones or other heavy material, or for hitting posts into the ground, etc.
Sleeper – It is also known as a tie or railroad tie. It is a transverse component laid perpendicular to the rails to hold them at the correct distance (gauge), maintain stability, and distribute the heavy load of a train from the rails to the underlying ballast and subgrade. Sleepers are made from different materials, including wood, concrete, and steel, and are an important part of the permanent way structure.
Sleeper spacing – It refers to the distance between successive railway sleepers (or ties), which are the components that lie beneath and support the rails. This distance is critical for the stability, strength, and proper load distribution of the railway track, since it influences the stiffness of the track structure. The ideal sleeper spacing is determined by factors such as the axle loads, traffic volume and speed, type of rail and sleeper, ballast characteristics, and subgrade bearing capacity.
Sleeve – Itis a tubular or cylindrical component used to encase, support, or protect another object or structure. It is frequently used create a penetration in a wall, ceiling, or floor for pipes or cables. Sleeves can also be used to reline pipes, protect shafts, or serve as a valve mechanism.
Sleeve bearing – It is also known as a journal bearing, plain bearing, or bushing. It is a type of bearing which uses a cylindrical sleeve to support a rotating shaft. It is characterized by a sliding motion between the sleeve and shaft, rather than a rolling motion like in ball or roller bearings. Sleeve bearings are frequently used in low-speed applications and are known for their simplicity and lower cost compared to other bearing types.
Sleeve coupling – It is one of the simple types of rigid coupling. It consists of a cylindrical sleeve keyed to the shafts to be connected. The sleeve transmits the torque from one shaft to the other. Normally sunk keys are used and in order to transmit the torque safely it is important to design the sleeve and the key properly. The key design is usually based on shear and bearing stresses.
Sleeve coupling with taper pins – In this coupling, torque transmission from one shaft to another is done using pins.
Sleeve pipe – It is a protective tube placed around a pipe where it passes through a wall, floor, or other structure to provide a barrier and allow for movement, protect against damage, and prevent the spread of fire or water. In structural applications, it can refer to a strong pipe designed to resist external pressure and forces.
Sleeves – These are the tubular fireclay shapes which encase an immersed metal rod in the valve assembly of a bottom-pouring ladle.
Slender-ness ratio – It is the effective unsupported length of a uniform column divided by the least radius of gyration of the cross-sectional area.
Slewing – It is rotation of the boom of a stacker around its central axis to discharge the material on the storage yard where needed.
Slicking (sleeking) – It is smoothing the surface of moulds.
Slickenside – It is the striated, polished surface of a fault caused by one wall rubbing against the other.
Slide – It is the main reciprocating member of a metal-forming press, guided in the press frame, to which the punch or upper die is fastened; sometimes called the ram. The inner slide of a double-action press is called the plunger or punch-holder slide, while the outer slide is called the blank-holder slide. The third slide of a triple-action press is called the lower slide, and the slide of a hydraulic press is frequently called the platen.
Slide adjustment – It is the distance which a press slide position can be altered to change the shut height of the die space. The adjustment can be made by hand or by power mechanism.
Slide gate – It is a mechanical valve system used to control the flow of molten steel from one vessel to another. It uses highly engineered refractory plates and nozzles, the working surfaces of which are corroded and eroded by the molten steel passing through them.
Slide gate plate – It is a refractory component, specifically a plate made from heat-resistant materials like alumina-carbon. It is, used in steelmaking to control the flow of molten steel. These plates are part of a slide gate system, which is used to regulate the flow of molten steel from a ladle or tundish to a continuous casting machine.
Slide gate refractory – It refers to the specialized, heat-resistant materials used in slide gate systems, which control the flow of molten steel in steelmaking operations. These materials are crucial for ensuring smooth and efficient casting processes by withstanding extreme temperatures and resisting erosion from molten steel.
Slider bearings – These are plain bearings which are low in capital costs but have high intensity of recurring expenditure. They are normally used in rolling mills of low capacities having a large number of manual operations. These bearings are usually suitable for the high temperatures and pressures which are normally encountered in these mills. These bearings are cheaper. Slider bearings have (i) high co-efficient of friction, (ii) relatively high starting and running torque because of high friction, (iii) higher power consumption in the rolling mill, and (iv) variation in size and shape. The life of these bearings is rather limited and the bearings need frequent changing. Because of low life, the rolling mill has fewer hot hours due to more wear and tear/breakage in the mill. These bearings are normally classified into two categories namely (i) slider bearings with metallic bush, and (ii) non-metallic bush bearings.
Slider bearings with metallic bush – These bearings have high co-efficient of friction and comparatively low life. The most popular slider bearing with metal bush which is normally used in low capacity rolling mills is the gun metal bearings. Gun metal provides a relatively cheap and easy to machine material, having good bearing properties and capable of withstanding high loads. Gun metal has a good strength and good corrosion resistance. It is easy to cast a gun metal. It typically contains 85 % copper, 5 % tin, 5 % lead and 5 % zinc.
Slider bed – It is a type of conveyor bed which utilizes a flat, sheet metal surface to support the conveyor belt. This design offers a stable and smooth transport of materials, particularly useful for odd-shaped objects.
Slider bed conveyor – It is an advanced conveyor variant featuring a streamlined, flat surface known as a slider bed, designed to adeptly support and transport diverse materials. Periodic examinations are crucial to gauge the condition and alignment of the slider bed, ensuring peak performance and longevity of the conveyor.
Slide rule – It is a hand-operated mechanical calculator consisting of slidable rulers for conducting mathematical operations such as multiplication, division, exponents, roots, logarithms, and trigonometry. It is one of the simplest analog computers. Slide rules exist in a diverse range of styles and normally appear in a linear, circular or cylindrical form. Slide rules manufactured for specialized fields such as aviation or finance typically feature additional scales which aid in specialized calculations particular to those fields. The slide rule is closely related to nomograms used for application-specific computations. Though similar in name and appearance to a standard ruler, the slide rule is not meant to be used for measuring length or drawing straight lines. It is not designed for addition or subtraction. Maximum accuracy for standard linear slide rules is around three decimal significant digits, while scientific notation is used to keep track of the order of magnitude of results.
Slide-sweep ratio – It is the ratio of sliding velocity to sweep velocity, e.g., in a pair of gears. In rolling, the slide-sweep ratio is called the slide-roll ratio.
Slide valve – It is also called sliding valve. It is a type of valve which controls fluid flow by a sliding element, such as a plate, disk, or spool, which moves across an opening to block or allow fluid flow. This movement is normally in a straight line, unlike a rotary valve which uses a rotating disc. This motion is typically linear, with the valve element sliding along a defined path to control the flow of substances.
Sliding – It is pure sliding with no rolling or spin). It is a motion of two relatively moving bodies, in which their surface velocities in the common contact area are different with regard to magnitude and / or direction.
Sliding abrasion – It is a type of abrasive wear in which a hard, rough surface slides across a softer surface, removing material from the softer surface through a combination of friction, pressure, and repeated rubbing. This occurs in both two-body and three-body contact scenarios; in two-body abrasion, the abrasive particles are attached to one surface, while in three-body abrasion, loose particles become trapped between the two surfaces, rolling and sliding to cause wear on both.
Sliding bearing – It is a bearing in which predominantly sliding contact occurs between relatively moving surfaces. Sliding bearings can be either unlubricated, liquid lubricated, grease lubricated, or solid lubricated.
Sliding chain – It refers to a type of mechanical linkage where one or more links move in a straight line (sliding) relative to another link. This is frequently used in conjunction with rotating links (cranks) to convert rotational motion into linear motion or vice-versa. Specifically, it is a four-bar linkage with one sliding joint and three rotating joints.
Sliding contact bearings – These are also known as plain bearings. These, are a type of bearing where two surfaces slide against each other without rolling elements, relying on a lubricant to reduce friction and wear. These bearings do best when the materials in contact are dissimilar. A steel shaft does not run in a steel bore, but it can run in a bronze lined bore (e.g., a bronze bushing). If similar materials are to be used, such as frequently the case in construction equipment where a steel pin runs inside a steel bore, one of the elements is to be harder than the other, so that the wear is concentrated in only one element, which can then be replaced instead of two. In addition, any abrasive particles tend to get forced into the softer material where they stay and instead of continually abrading the parts, they just wear a groove in one of the parts. A sliding contact radial bearing element which is used to support a shaft is called a bushing (bush bearing), and sometimes it has integral flanges to also support axial loads. In this the ‘bush’ of soft material like brass or gun metal is provided and the body or main block is made of cast iron. Bush is hollow cylindrical piece which is fitted in housing to accommodate the mating part. When the bush gets worn out it can be easily replaced. When a bearing, such as a bushing, is placed in a modular structural housing, the assembly is called a pillow block. Hinges are another type of special mounting, and most also have sliding contact bearing elements between the two sides.
Sliding contact fatigue – It is a form of contact fatigue in which repeated cyclic loading between two contacting surfaces, with some degree of relative motion (sliding), leads to the formation of cracks and material removal, resulting in surface damage like pitting and spalling. The sliding component introduces shear stresses, which can increase subsurface stress concentration, accelerate crack initiation, and shift stress distribution closer to the surface, making it a more severe condition than pure rolling contact fatigue.
Sliding friction – It is the resistance force which opposes the relative motion of two solid surfaces as they slide against each other. It is also known as kinetic friction. This force acts in the opposite direction to the object’s movement and arises from the microscopic irregularities on the surfaces which interlock and resist motion. It is always less than static friction.
Sliding or static guides – The entry and exit guides of sliding type are also known as static guides. The design of these guides is based on sliding friction. These guides normally comprise of a guide box, two opposed blocks mounted in the guide box on opposite sides of the mill pass line and having longitudinally extending channels in their adjacent faces, separate metal plates bridging the respective channels and shaped to fit closely against the sides of the rolling stock traveling through the guide, and means to circulate water through the channels in contact with the outer surfaces of the plates. Static guides are robustly designed guides to withstand the demanding rolling mill environment. The design of the guides is to suite the specific roll pass requirement of the mill. Static guides usually feature a common guide holder so as to allow for reduced requirements of stock and spares. These guides can be adapted for all types of stand and rest bars configurations.
Sliding joint – It refers to a joint in a refractory lining, or a piece of refractory material, which allows for movement or sliding to accommodate thermal expansion and contraction without causing cracks or stress on the lining. This is crucial since refractories, being used in high-temperature applications, experience significant temperature fluctuations, leading to expansion and contraction.
Sliding mode control – It is a control strategy for a non-linear system which uses discontinuous control signals.
Sliding piston – It is defined as a component in a two-stroke engine cycle which moves linearly within a cylinder, driven by gas pressure and other forces, functioning similarly to a mass-spring system.
Sliding seal – It is the lower cylinder seal in a pneumatic piston-style actuator designed for rotary valve service. This seal permits the actuator stem to move both vertically and laterally without leakage of lower cylinder loading pressure, allowing for a single rod end bearing.
Sliding stem – It is a type of valve stem which does not rotate or turn. It slides in and out the valve to open or close the valve. This design is used in hand-operated lever rapid opening valves. It is also used in control valves which are operated by hydraulic or pneumatic cylinders.
Sliding vane compressor – It is a type of positive displacement compressor which uses a rotating rotor with sliding vanes to compress air or gas. These vanes trap and reduce the volume of the gas, thereby increasing its pressure. This process is repeated as the rotor rotates, continuously compressing the gas.
Sliding velocity – It is the difference between the velocities of each of the two surfaces relative to the point of contact.
Sliding wear – It is a phenomenon which results in material loss between contact surfaces mainly because of the area contact, frequently occurring under lubricated conditions. It can be assessed through standard test procedures such as pin-on-disk and ball-on-disk experiments.
Slime – It is a material of extremely fine particle size encountered in ore treatment. It is a mixture of
metals and some insoluble compounds which forms on the anode in electrolysis.
Slime (electrolysis) method – It is a direct methos to evaluate steel cleanliness. It is an accurate method but time consuming. A relatively large (200 grams to 2 kilograms) steel sample is completely dissolved in hydrochloric (HCl) acid and the non-metallic inclusions (NMIs) which remain undissolved are collected for counting and further analysis. Alternatively, in order to protect iron oxide (FeO) inclusions, most of the dissolution is accomplished by applying electric current through the steel sample immersed in a ferrous chloride (FeCl2) or ferrous sulphate (FeSO4) solution. This method is used to reveal the individual, intact inclusions.
Sling angle – It is the horizontal angle between a lifting sling leg and the horizontal plane when attached to a load and the hoisting hook. This angle is critical since it dictates the tension on each sling leg. As the sling angle decreases (gets closer to horizontal), the tension on the sling legs increases considerably, reducing the sling’s effective load-carrying capacity. A normal industry practice is to keep sling angles at 60-degree or above to maintain adequate capacity, with a minimum recommended angle of 30-degree.
Slings – Slings are accessories used for lifting and transferring of loads with the help of cranes, telphers, or hoists. Slings enable in the activities related to create anchors, attach to loads, lift loads, pull loads, and lower loads. The dominant characteristics of a sling are determined by the components from which it is made. As an example, the strengths and weaknesses of a sling made of steel wire rope are essentially the same as the strengths and weaknesses of the wire rope from which it is made. Slings are normally one of six types namely (i) chain, (ii) wire rope, (iii) metal mesh, (iv) natural fiber rope, (v) synthetic fibre rope, or (vi) synthetic web. Slings enable in the activities related to create anchors, attach to loads, lift loads, pull loads, and lower loads.
Slip – It is a suspension of finely divided ceramic material in liquid. It is also the plastic deformation by the irreversible shear displacement (translation) of one part of a crystal relative to another in a definite crystallographic direction and normally on specific crystallographic plane. It is sometimes called glide. In composites, slip is the relative collinear displacement of the adherends on either side of the adhesive layer in the direction of the applied load.
Slip angle – It is the angle at which a tensioned fibre slides off a filament-wound dome. If the difference between the wind angle and the geodesic angle is less than the slip angle, fibre does not slide off the dome. Slip angles for different fibre-resin systems vary and are to be determined experimentally.
Slip band – It is a group of parallel slip lines so closely spaced as to appear as a single line when observed under an optical microscope.
Slip band formation – It refers to the development of regions of concentrated, localized strain within a material’s grains, mainly because of the sliding of crystal planes (slip) along specific directions. These bands typically appear on characteristic slip planes and can persist even under significant strain. They are a manifestation of plastic deformation where blocks of a crystal slide over each other along defined planes.
Slip casting – It is a ceramic forming technique where a liquid slurry, called slip, is poured into a mould, and the mould absorbs water from the slip, allowing a solid ceramic layer to form on the walls of the mould. This process is normally used to create complex shapes. It is also a method of forming metal shapes by pouring a stabilized water suspension of metal powders into the shaped cavity of a fluid-absorbing mould, diffusing the liquid into the mould wall, removing the casting from the mould and sintering. In ceramics, it is a pouring slip, a water suspension of finely ground clay, into a plaster of Paris mold. After it hardens it is dried and fired.
Slip crack – It is a rupture in the pressed compact caused by the mass slippage of a part of the compact.
Slip direction – It is the crystallographic direction in which the translation of slip takes place.
Slip flask – It is a tapered flask which depends on a movable strip of metal to hold foundry sand in position. After closing the mould, the strip is refracted and the flask can be removed and reused. Moulds hence made are normally supported by a mould jacket during pouring.
Slip joint – It is a structural connection designed to allow controlled sliding movement between two adjacent parts, typically to absorb expansion, contraction, or differential settlement without inducing damaging stresses or cracks. They work by having a smooth or flexible interface which facilitates one element sliding over another, and are normally used in construction for walls and slabs, in bridge decks, or in downhole drilling to accommodate varying lengths.
Slip line – It is the visible traces of slip planes on metal surfaces. The traces are (normally) observable only if the surface has been polished before deformation. The normal observation on metal crystals (under a light microscope) is of a cluster of slip lines known as a slip band.
Slip on weld flange – Slip-on weld flanges are designed to slip over the outside of pipe, long-tangent elbows, reducers, and swages and then fillet welded. The flange has poor resistance to shock and vibration. The flange is easier to align than welding neck flange. This flange is ideal for low pressure applications since the strength when under internal pressure is about one third that of a weld neck flange. Slip-on flanges are easy to use in fabricated applications. They are typically used for low hazard moderate services where pressure fluctuations, temperature fluctuations, vibrations and shock are not expected to be severe such as fire water service, cooling water service etc. Since the pipe is ‘double-welded’ both to the hub and the bore of the flange, hence radiography is not practical. Normally magnetic particle inspection or dry particle inspection methods are used to check the integrity of the weld. Where specified, the slip-on weld flanges are used on pipe sizes greater than 40 millimeters with a preference for the socket weld flange for sizes up to and including 40 millimeters. The strength of slip-on flange is around 2/3 times to that of weld neck flange. The fatigue life of this type of flange is 1/3 that of a weld neck flange. This flange is widely used because of its greater ease of alignment in welding assembly and because of its low initial cost.
Slippage – It refers to unintended, relative movement between parts or materials, such as a belt on a pulley, soil on a slope, or fibres within a composite. It signifies a loss of intended grip or connection and frequently results in decreased efficiency, performance issues, or even failure. Common examples include conveyor belts failing to maintain grip on pulleys, soil moving on a steep incline, or excessive movement between fibres in a reinforced material. Slippage is also the undesired movement of the adherends with respect to one another during the bonding process.
Slippage scratch – It is a short longitudinal indentation parallel to the rolling direction.
Slipping – The collapsing of the blast furnace hanging is a phenomenon called ‘slipping’ during which the charged materials fall uncontrollably toward the hearth of the furnace in a thermally unprepared state which leads to the furnace getting cold. It also forces the hot gases upward with the force of an explosion.
Slip plane – It is the crystallographic plane in which slip occurs in a crystal. It is a specific plane within a crystal lattice where permanent displacement, or slip, occurs during plastic deformation when the elastic limit is exceeded. These planes typically have the highest density of atoms, facilitating easier sliding movements under applied stress.
Slip ring – It is a sliding continuous electrical contact between a machine’s rotating parts and the fixed external circuit.
Slip system – It is the combination of slip plane with the close-packed slip directions which lie in the plane.
Slit rolling – It is the most economical rolling process which allows high production rates also for small size bars and a significant reduction in the production cost. The slit rolling process enables production of two, three, four or even five bars from one billet. The slitting process uses special passes and guides to prepare, shape and longitudinally separate the incoming material into two or more individual strands, which is then further rolled into the finished sizes. This process of rolling bars is also called ‘multi slit rolling’ (MSR). The process of slit rolling is to roll two or more bars simultaneously from a single billet. When compared with the conventional single strand continuous rolling, multi slit rolling process technology has reduced the number of passes. The multi slit rolling process technology is very frequently employed during the rolling of the ribbed reinforcement bars.
Slit rolling technology – It consists of a combination of mill roll pass design combined with specific rolling guides to uniformly separate the incoming rolling stock longitudinally in two or more sections, which can be rolled to finish sizes. This is done to improve mill utilization when rolling smaller sections.
Slitter – It consists of supporting structure and two parallel arbors, one above the other, mounted with shear slitter knives. The distance between two parallel slitter arbors is vertically adjustable to accommodate different diameter knives and different thicknesses of materials. This is normally done during slitter tooling setup or beginning of slitting. However, some computer numerical control precision slitters can perform a continuous minor adjustment as per the conditions of an incoming strip during slitting.
Slitter hair – It consists of minute hairlike sliver along edge(s) because of the shearing or slitting operation.
Slitting – It is the simultaneous cutting of a coil or wide strip into a number of narrower strips by means of rotary cutters. It is the cutting or shearing along single lines to cut strips from a metal sheet or to cut along lines of a given length or contour in a sheet or work-piece. Slitting is a process to cut a single, wide strip, sheet or plate, normally in coil form, length-wise into a number of narrower strips. During slitting, a moving strip passes between a number of circular blades or knives mounted on two parallel rotating arbors. Slitting can be applied to several materials including steel strips, from very thin strips (less than 0.1 millimetre) to over 25 millimetres thick plate.
Slitting guide – These guides are used for the slitting of the rolling stock. The range of slitting guides which have been developed facilitates 2, 3, 4 or 5 strand slitting. These guides are designed to provide optimum a stable product for the separating process. The guides are of fabricated steel construction and comprise of entry stripper, separating rolls, knife cassette, and exit tubes. The design also incorporates single point gap adjustment of the separating rolls.
Slitting line – It is a process line which cuts a wide coil of material into multiple narrower strips or coils. This is achieved using rotating circular knives that slice the metal along its length. A slitting line refers to the entire system or process, including the uncoiling, slitting, and recoiling of the material. Slitting lines normally have either one or two coilers, although some are equipped with individual coilers for each cut produced. On lines with only one coiler, all cuts are wound on this coiler and metal-separating disks or overarm separators are used to keep the individual cuts separated during winding. A disadvantage of single coilers arises in slitting several cuts since the separator thickness is to be accommodated between adjacent cuts, resulting in a fan-out pattern of the cuts from the tight-line slitter. This situation can induce undesired camber and rippled edges in the slit metal. To avoid this problem, two coilers are normally used such that each takes up every other cut across the width, hence eliminating fanout. Slitting lines are normally classified into three broad categories namely (i) pull-through, (ii) driven, and (iii) help-driven. The choice between pull-through and driven lines depends largely on strip shear strength and thickness, number of slit strips, slitting speed, and slit quality requirements.
Slitting shears – These are rotating circular knives which slice the wider metal strip along its length into narrower strips. These shears are also used for the trimming of strip edges.
Sliver – It is an imperfection consisting of a very thin elongated piece of metal attached by only one end to the parent metal into whose surface it has been worked. Sliver also refers to a localized, elongated surface irregularity or tear on a metal product, frequently appearing as a raised, elongated, or pulled-up region. Slivers are typically defined as loose or torn segments of steel which have been rolled into the surface of the bar or coil. They can appear as elongated, chevron-shaped, or pulled-up areas on the surface. These defects can be caused by several factors during the rolling, casting, or processing of steel, and they are normally observed in hot-rolled coils and other metal products.
Slope – It is also called gradient of a line. It is a number which describes the direction of the line on a plane. It is calculated as the ratio of the vertical change to the horizontal change between two distinct points on the line, giving the same number for any choice of points.
Slope angle – It is also called angle of inclination. It is the angle between a ground surface or embankment and a horizontal plane. It is important for assessing and ensuring the stability of slopes by determining gravitational forces and resulting stresses on the ground or construction materials.
Slope belt – It is a conveyor belt which is used to carry material along an inclined flight. Sometimes called drift conveyor.
Slopping – It is the general term used when, because of the excessive foam growth, the foam cannot be contained within the converter and the foam flows down the outer side of the converter with the pace depending upon the oxidizing state of the slag. The pace is slow in case of a thick under-oxidized slag and fast in the case of a runny over-oxidized slag. The avoidance of the slopping needs a tight control on the slag composition and, hence, the oxidizing state of the foam. If the slag is under-oxidized, the apparent viscosity becomes too high, which occurs if the iron oxide (FeO) content at the start of the main decarburization period is too low. This results in ‘dry’, very viscous foam during the middle part of the blow. If the slag is over-oxidized, the gas generation rate and, hence, the gas velocity within the foam becomes too high. The slopping causes can be divided in two groups depending of the type namely (i) static or (ii) dynamic. Static causes are related to the pre-blow operational conditions, such as the design of the converter and the volume and characteristics of slag, the quality of the charge materials, especially hot metal and scrap, blow patterns which control the positioning of the oxygen lance, time of additions and oxygen flow. The dynamic causes are related to types of blows, such as deflection of blow patterns and the extent of agitation at the bottom of the converter. The slopping can occur due to the excessive growth of the gas-slag-metal emulsion. The foam can flow out depending on the degree of oxidation of the slag, i.e., it can happen slowly in the case of a dense and low-oxidized slag, and rapidly in the case of a highly oxidized slag.
Slop tank – It is a specialized storage vessel designed to collect oily mixtures, such as tank washings and drainings, from other tanks. These tanks facilitate the separation of oil and water, frequently through processes like heating and settling, to enable the environmentally responsible disposal of the water or the recovery of valuable oil. They are crucial for complying with environmental regulations.
Slot feeder – It is a type of bulk material feeder which uses a slot or opening to control the flow of material from a storage area, like a bin or hopper, into a processing or handling system. It is designed to provide a wider, more even distribution of material compared to other feeder types like chutes or pipes. The slot’s width can be adjusted to regulate the material volume.
Slot furnace – It is a common batch furnace for heat treating metals where stock is charged and removed through a slot or opening.
Slotting – It is the cutting a narrow aperture or groove with a reciprocating tool in a vertical shaper or with a cutter, broach, or grinding wheel.
Slot weld – It is a type of weld where one piece of material is joined to another through an elongated hole (or slot) in the top piece. The hole is then filled with weld material to fuse the two parts together. Slot welds are used to create strong, durable joints, especially when more strength is needed than a plug weld can provide.
Slot welding process – It is a joining process where two metal parts are connected by welding along the edge of a rectangular or elongated hole (a slot) in one of the parts. This weld fills the slot, thereby joining the two parts together. The hole can be open at one end and can be partially or completely filled with weld metal.
Slow combustion – It is a low-temperature, frequently incomplete oxidation process where heat is gradually released without a visible flame, characterized by a small flame propagation rate. Unlike rapid combustion, which produces quick heat and light, slow combustion involves the gradual transfer of heat from the hot combustion products to the unburned fuel, sustained by the oxygen attacking the fuel’s surface. Examples include the rusting of iron, the decay of organic materials, and the smoldering of wood or coal
Slowing factor – It is the ratio of the wave wavelength of a ‘native’ transmission line to the wavelength in a slow-wave structure. The higher the slow-wave factor, the more the transmission line’s wavelength is reduced compared to its ‘normal’ wavelength in the chosen dielectric medium.
Slow sand filtration (SSF) – It is a biological water treatment process which removes suspended solids, pathogens, and other impurities from raw water by passing it slowly through a bed of fine sand. It relies on a combination of mechanical straining and a biological layer, the Schmutzdecke, which develops on the sand surface and contains micro-organisms that consume organic matter and pathogens. This simple, low-cost method is effective for producing safe drinking water, especially in rural communities, though it needs a large land area and is best suited for water with low initial turbidity.
Slow strain rate technique – It is an experimental technique for evaluating susceptibility to stress-corrosion cracking. It involves pulling the sample to failure in uniaxial tension at a controlled slow strain rate while the sample is in the test environment and examining the sample for evidence of stress-corrosion cracking.
Slow strain rate testing (SSRT) – It is also known as constant extension rate tensile testing (CERT). It, is a mechanical testing method used to evaluate the behavior of materials under tensile stress at a controlled, gradual rate of strain. It involves applying tensile force to a specimen at a constant rate while monitoring its elongation until fracture. Slow strain rate testing is normally used to study stress corrosion cracking (SCC) susceptibility in several materials.
Slow sand filtration – It is a water treatment process where water flows slowly through a bed of fine sand, relying on biological and physical processes to remove impurities. A key component is the ‘Schmutzdecke’, a biological layer which forms on the sand surface, trapping and removing suspended solids, pathogens, and other contaminants.
Slow strain rate technique – It is an experimental technique for evaluating susceptibility to stress-corrosion cracking. It involves pulling the sample to failure in uniaxial tension at a controlled slow strain rate while the sample is in the test environment and examining the sample for evidence of stress-corrosion cracking.
Slow strain rate testing (SSRT) – It is also known as constant extension rate tensile (CERT) testing. It is a mechanical testing method used to evaluate a material’s susceptibility to stress corrosion cracking (SCC) and other environmentally-assisted cracking phenomena. It involves applying a slow, constant tensile strain rate to a specimen while it is exposed to a specific environment. The test helps determine how the material behaves under these conditions, particularly its resistance to cracking.
Slow wave structures – These structures act to reduce the group velocity of a transmission line, or increase its group delay compared to a normal “fast-wave” structure. Slow-wave structures are useful in shrinking electrically-long elements. In microwave engineering, cost is a linear function of circuit area, so any tricks we can employ to shrink designs are worth knowing about. One of the applications of slow-wave circuits is in time delay networks.
Sludge – It consists of rock cuttings from a diamond drill hole, sometimes used for assaying. It is also an accumulation of insoluble materials and reaction products which collects in cleaning and processing tanks. It is also the accumulated wet or dry solids which are separated from waste-water during treatment. This includes precipitates resulting from the chemical or biological treatment of waste-water. It is also a soft water-formed sedimentary deposit which normally can be removed by blowing down.
Sludge age – It is also known as ‘mean cell residence time’ (MCRT) and ‘solids retention time’ (SRT). It is calculated as the total quantity of sludge in the aeration tank and clarifier divided by the daily sludge losses through waste activated sludge and effluent. Sludge age can vary from 0.5 day to 75 days in low-growth rate systems. Sludge age is an indication of F/M (food to microorganism) ratios. Shorter times are indicative of high F/M ratios and longer times are indicative of low F/M ratios. Sludge age is expressed by the equation ‘sludge age = sludge mass in (aeration tank + clarifier) / daily sludge losses’. The quality of sludge age can be determined using a microscope at 100x magnification.
Sludge digestion – It refers to the process of anaerobically treating sewage sludge to produce biogas, which contains methane, carbon di-oxide, and other components, as well as a decomposed substrate.
Sludge pond – It is a containment structure designed to store, thicken, and dewater sludge which settles from wastewater or industrial processes. These ponds are engineered with features like impermeable liners to prevent ground-water contamination and are subject to design for factors like flooding and overflow. The sludge, composed of concentrated solid particles, can undergo anaerobic digestion to reduce its volume and stabilize it for further treatment or disposal.
Sludge production – It is also called sludge yield. The decay of biomass produces sludge. For conventional industrial systems, sludge production can be as low as 0.15 kilograms per kilogram of biological oxygen demand (BOD), such as in coke making.
Sludge recirculation rate – A portion of the sludge produced is recirculated to promote the production of more sludge in the aeration tank. It is the ratio between the sludge recirculation volumetric flow and treatment volumetric inflow. In any case, the capacity of the sludge recirculation system is not to be less than 200 % of the daily average total inflow.
Sludge thickening – It is the process of sedimentation and compression of sludge particles under the influence of gravity, aimed at increasing the concentration of dry matter in the sludge to around 4 % to 6 %. This process can occur periodically or continuously in gravitational thickeners, where sludge is separated from the liquid phase.
Sludge treatment – It is the process of managing the sludge generated during waste-water purification to remove organic matter, metals, and micro-organisms before its disposal or utilization. Common methods include anaerobic digestion, aerobic digestion, composting, and, less frequently, incineration.
Slug – It is a short piece of metal to be placed in a die for forging or extrusion. It is a small piece of material produced by piercing a hole in sheet material. Slug is a large ‘dose’ of chemical treatment applied internally to a steam boiler intermittently. It is also used sometimes instead of ‘priming’ to denote a discharge of water out through a boiler steam outlet in relatively large intermittent quantities.
Slugging – It is the act of adding a separate piece or pieces of material in a joint before or during welding which results in a welded joint not complying with design, drawing, or specification requirements.
Slug mode – It is an intelligent operational mode within a conveyor system where packages undergo automatic separation while traversing the conveyor route. This automated process improves efficiency and precision in material handling. Continuous monitoring is necessary to fine-tune and optimize slug mode functionality for flawless package separation.
Slugs – Slugs are surface discontinuities found on the inner surface of seamless (extruded) pipes. These occur when some metallic pieces which are stuck on the mandrel, are torn and fused back on the inner surface of the pipe.
Sluice valve – It is a gate valve or a sluice gate valve and is described as a valve which uses a gate or wedge shape disk which slides perpendicular to the flow of the fluid into or out of the pipeline.
Slumpability – It is the flow of gravity of a grease in a container, allowing it to feed out into a pump or can. Slumpability also influences the leakage of grease from a bearing.
Slump test – It is a test which is used to determine the consistency of slip in which measurement is made of the spreading of a specified volume of slip over a flat plate.
Slurry – It is a thick suspension of solids in a liquid, typically water, which remains mobile and coherent under low stress. It is a mixture of solid particles in a liquid, of such consistency so as to be capable of being pumped like a liquid. It is used for several purposes, including transporting materials, separating minerals, and in construction. In foundry, slurry is a flowable mixture of refractory particles suspended in a liquid. Thin watery mixture such as the gypsum mixture for plaster moulding, the moulding medium used for investment casting, core dips, and mould washes.
Slurry abrasion response (SAR) number – It is a measure of the relative abrasion response of any material in any slurry, as related to the instantaneous rate of mass loss of a sample at a specific time on the cumulative abrasion-corrosion time curve, converted to volume or thickness loss rate
Slurry abrasivity – It is the relative tendency of a particular moving slurry to produce abrasive and corrosive wear compared with other slurries.
Slurry erosion – It is the erosion which is produced by the movement of a slurry past a solid surface.
Slurry preforming – It is the method of preparing reinforced plastic preforms by wet processing techniques similar to those used in the pulp moulding industry, e.g., glass fibres suspended in water are passed through a screen which passes the water but retains the fibres in the form of a mat.
Slurry pump – It is a type of pump designed to handle a mixture of liquid and solid particles, typically driven by V-belts to allow for adjustments in performance to meet varying field conditions, hence optimizing power usage and minimizing wear.
Slurry reactor – It is a type of reactor which facilitates liquid-solid reactions, wherein gas is bubbled into a slurry to improve mixing and mass transfer, frequently utilizing the principles of hydraulic gradients for circulation.
Slush casting – It is a hollow casting normally made of an alloy with a low but wide melting temperature range. After the desired thickness of metal has solidified in the mould, the remaining liquid is poured out. It is considered as an obsolete practice.
Slush casting process – It is a variant of permanent mould casting to create a hollow casting. In the process the liquid metal is poured into the mould and allowed to cool until a shell of material forms in the mould. The remaining liquid metal is then poured out to leave a hollow shell. The resulting casting has good surface detail but the wall thickness can vary. The process is usually used for low melting point metals. It uses less material than solid casting, and results in a lighter and less expensive product. Hollow cast figures generally have a small hole where the excess liquid was poured out. Similarly, a process called ‘slush moulding’ is used in automotive thermoplastic dashboard manufacture, where a liquid resin is poured into a hot, hollow mould and a viscous skin forms and then excess slush is drained off, the mould is cooled, and the moulded product is stripped out.
Slushing compound – It is an obsolete term describing oil or grease coatings which is used to provide temporary protection against atmospheric corrosion.
Slushing oil – It is a mineral oil containing additives which enable it to protect the parts of a machine against rusting.
Small and medium-sized enterprises (SME) – These organizations are characterized by having fewer employees and lower revenue or assets compared to large organizations. The specific definition of an small and medium-sized enterprises can vary by country, industry, and even by the specific organization defining it.
Small-angle neutron scattering (SANS) – It is a technique which uses the scattering of neutrons to study the structure of materials at a mesoscopic scale, typically ranging from 1 nanometer to 100 nanometers. It is particularly useful for investigating structures with dimensions of tens or hundreds of Angstroms, like polymers, biological molecules, and magnetic systems.
Small-angle X-ray scattering (SAXS) – It is a technique which is used to study the structural organization of materials at the nanoscale, typically between 1 nanometer and 1,000 nanometers. It works by analyzing the intensity of X-rays scattered at small angles when a sample is illuminated with a collimated X-ray beam. The scattered X-rays provide information about the size, shape, and spatial arrangement of structures within the sample.
Small-scale mining – It is a labour-intensive, low-technology, and frequently informal method of extracting minerals from the earth, typically using minimal machinery and relying on manual labour. It presents considerable environmental and health risks and can operate outside formal regulations.
Small scale yielding (SSY) – It describes a state where the plastic zone (region of non-elastic deformation) at a crack tip is small relative to the dimensions of the crack or the structure it is in. This allows for the use of linear elastic fracture mechanics (LEFM) to analyze crack propagation, even in cases where plasticity is present.
Small-signal model – It is an analytical tool for systems that show significant non-linearity for large signal excursions.
Smart gadgets – These refer to electronic devices which frequently need significant, instantaneous currents, which can be supported by integrating supercapacitors to improve performance and reduce costs. Examples include several personal application devices.
Smart grid – It is the application of information technology to improve performance of the electrical grid.
Smart growth – It is an overall approach of development and conservation strategies which can help protect people’s health and natural environment and make the communities more attractive, economically stronger and resilient to climate change. Smart growth has a set of ten basic principles to guide smart growth strategies. These are (i) mix land uses, (ii) take advantage of compact building design, (iii) create a range of housing opportunities and choices., (iv) create walkable neighborhoods, (v) foster distinctive, attractive communities with a strong sense of place, (vi) preserve open space, farmland, natural beauty and critical environmental areas, (vii) strengthen and direct development towards existing communities, (viii) provide a variety of transportation choices, (ix) make development decisions predictable, fair and cost effective, and (x) encourage community and stakeholder collaboration in development decisions.
Smart-phone – It is a mobile phone with integrated computing capabilities, a mobile operating system, and advanced features beyond traditional calling and texting. It functions like a handheld computer, offering internet access, the ability to run software applications, and access to services such as email, social media, multimedia, and GPS (Global Positioning System) navigation, all within a portable, touch-screen device.
Smart transmitters, valves, and fieldbus – Smart transmitters and valves are intelligent devices in process automation which utilize microprocessors for improved functionality, while fieldbus refers to a digital communication network for connecting these devices. Smart transmitters incorporate sensors, microprocessors, memory, and communication modules, allowing them to perform calculations, self-diagnostics, and communication with other devices. Smart valves, similarly, incorporate intelligence and communication capabilities for precise control and monitoring. Fieldbus is a communication protocol that enables real-time, closed-loop control between smart devices and host systems.
SME – It is the abbreviation for small-sized / medium-sized enterprise or subject matter expert.
Smearing – It means mechanical removal of material from a surface, normally involving plastic shear deformation, and redeposition of the material as a thin layer on one or both surfaces.
Smelt – It means to extract (metal) from its ore by a process involving heating and melting. It is a batch or lot of frits. It is molten slag in the pulp and paper industry, the cooking chemicals tapped from the recovery boiler as molten material and dissolved in the smelt tank as green liquor.
Smelter – It is a facility or furnace used to extract metals from their ores through a process called smelting. Smelting involves heating the ore to high temperatures, frequently with the addition of a reducing agent, to decompose the ore and separate the desired metal.
Smelting – It is the thermal processing wherein chemical reactions take place to produce liquid metal from a beneficiated ore. Smelting is a stage in the extraction of copper from its ores. The ore concentrate is melted, with a flux, in a reverberatory furnace to produce copper matte, a mixture of copper and iron sulphides which contains 30 % copper to 40 % copper.
Smelting furnace – It is a refractory lined furnace in which smelting process is carried out. Smelting uses heat and a chemical reducing agent to decompose the ore, driving off other elements as gases or slag and leaving the metal behind.
Smelting reduction (SR) processes – These processes combine the gasification of non-coking coal with the melt reduction of iron ore. Energy intensity of smelting reduction processes is lower than that of blast furnace, since the production of coke is not needed and the need for preparation of iron ore is also reduced. These processes are based on non-coking coal as the main fuel and reductant and aim for a liquid iron product. Several of these processes propose to use tonnage oxygen as the oxidant to enable the process heat requirements to be satisfied by combustion of the coal fuel. A few envisage large scale usage of electrical heating as the source of process heat.
Smelting temperature – It is the specific, high temperature at which a metal ore is heated to extract the desired metal from its impurities, causing the ore and by-products to melt and separate into a molten metal and a waste material called slag. This temperature is to be high enough to facilitate the chemical reduction of the ore and the subsequent melting and separation of the metal from the molten slag, which is necessary for purification. Smelting needs extremely high temperatures, frequently in the range of 1,000 deg C to 1,600 deg C to achieve chemical reactions and melting.
Smith chart – It is a graphical tool for display of the impedance of devices at varying frequencies, and for solution of problems of impedance matching in radio frequency design.
Smith forging – It is also called hand forge or smith forge. It is a forging operation in which forming is accomplished on dies which are normally flat. The piece is shaped roughly to the needed contour with little or no lateral confinement; operations involving mandrels are included. The term smith forge refers to the operation performed, while smith forging applies to the part produced.
Smithsonite – It is also known as zinc spar. It is the mineral form of zinc carbonate (ZnCO3). Smithsonite is a variably coloured trigonal mineral which only rarely is found in well-formed crystals. It has a Mohs hardness of 4.5 and a specific gravity of 4.4 to 4.5.
Smith-Watson-Topper (SWT) parameter – It is a fatigue damage parameter used to predict the fatigue life of metal materials in uniaxial load states, particularly those with non-zero mean stresses. It is based on a stress-strain approach rather than an energy criterion, and its original form was designed to estimate fatigue life up to crack initiation.
Smog – It is a form of air pollution which reduces visibility, frequently appearing as a hazy or smoky fog. It is a mixture of pollutants, including smoke, fog, dust, and harmful substances like nitrogen oxides and volatile organic compounds. Smog is not just a combination of smoke and fog; it is a complex mix of pollutants which can have significant negative impacts on human health and the environment.
Smoke – It consists of small gas borne particles of carbon or soot, less than 1 micro-meter in size, resulting from incomplete combustion of carbonaceous materials and of sufficient number to be observable. It is a suspension of airborne particulates and gases, normally an unwanted byproduct of combustion, while exhaust gas is the gas discharged from a furnace after combustion. Smoke is frequently associated with fires and incomplete combustion, containing unburnt particles like soot, tar, and ash. Exhaust gas, on the other hand, is a broader term encompassing different gases and particulate matter resulting from the burning of fuel.
Smooth finish – It is the finish of a flange. It can be made with several different types of tool shapes. No tool markings are to appear to the naked eye on the surface. The roughness of the finish is from 5 micro millimeters to 10 micro millimeters.
Smoothing – It is the process of removing fluctuations in an ordered series so that the result is ‘smooth’ in the sense that the first differences are regular and higher order differences are small. Although smoothing can be carried out by free-hand methods, it is normal to make use of moving averages or the fitting of curves by least squares procedures. The philosophical grounds for smoothing stem from the notion that measurements are made with error, such that artificial ‘bumps’ are observed in the data, whereas the data really is to represent a smooth or continuous process. When these ‘lumpy’ data are smoothed appropriately, the data are thought to better reflect the true process which generated the data. An example is the speed-time trace of a vehicle, where speed is measured in integer kilometres per hour. Accelerations of the vehicle computed from differences in successive speeds are over-estimated because of the lumpy nature of measuring speed. Hence, an appropriate smoothing process on the speed data results in data which more closely resembles the underlying data generating process. Of course, the technical difficulty with smoothing lies in selecting the appropriate smoothing process, since the real data are never typically observed.
Smooth liner – It is a type of smooth geo-membrane, frequently made of high-density poly-ethylene (HDPE) or linear low-density poly-ethylene (LLDPE), used for creating an impermeable barrier in containment applications.
Smudge – It is a dark film of debris, sometimes covering large areas, deposited on the sheet during rolling.
Smut – It is a reaction product sometimes left on the surface of a metal after pickling, electroplating, or etching.
Snag – It is a minor defect, fault, or problem that needs to be identified and fixed before a project can be considered complete. In castings, snag means removal of fins and rough places on a casting by means of grinding.
Snagging – It is the heavy stock removal of superfluous material from a work-piece by using a portable or swing grinder mounted with a coarse grain abrasive wheel. It also means offhand grinding on castings and forgings to remove surplus metal such as gate and riser pads, fins, and parting lines.
Snake – It is the product formed by twisting and bending of hot metal rod prior to its next rolling process. It is also a crooked surface imperfection in a plate, resembling a snake. Snake is also a flexible mandrel used in the inside of a shape to prevent flattening or collapse during a bending operation.
Snaking – It is a series of reversing lateral bows in coil products. This condition is caused by a weaving action during an unwinding or rewinding operation.
Snap – It is also known as snap hook or spring hook. It is a hook with a spring snap in its ends to prevent the accidental unhooking of a rope, cord, or other target line. Snaps are a common but essential component in a huge range of industrial applications.
Snap flask – It is a foundry flask hinged on one corner so that it can be opened and removed from the mould for reuse before the metal is poured.
Snap shears – These shears are normally arranged at the entry side of rolling mill stand 1. They are used for dividing the hot input material conveyed to the rolling mill.
Snap temper – It is a precautionary interim stress-relieving treatment applied to high-hardenability steels immediately after quenching to prevent cracking because of delay in tempering them at the prescribed higher temperature.
Sn content – It refers to the quantity of tin present in a material, which can influence its mechanical properties, such as fracture stress.
S-N curve – It is a graph of stress (S) against the number of cycles to failure (N). The stress can be the maximum stress (Smax) or the alternating stress amplitude (Sa). The stress values are normally nominal stress, i.e., there is no adjustment for stress concentration. The graph indicates the S-N relationship for a specified value of the mean stress (Sm) or the stress ratio (A or R) and a specified probability of survival. For ‘N’ a log scale is almost always used. For ‘S’ a linear scale is used very frequently, but a log scale is sometimes used. It is also known as S-N diagram.
S-N curve for 50 % survival – It is a curve fitted to the median value of fatigue life at each of several stress levels. It is an estimate of the relation between applied stress and the number of cycles-to-failure which 50 % of the population survives.
S-N curve for ‘p’ % survival – It is a curve fitted to the fatigue life for ‘p’ % survival values at each of several stress levels. It is an estimate of the relationship between applied stress and the number of cycles-to-failure that ‘p’ % of the population survive. ‘p’ cam be any number, such as 95, 90, and so forth.
S-N diagram – It is a plot of stress (S) against the number of cycles to failure (N) in fatigue testing. A log scale is normally used for ‘N’. For ‘S’, a linear scale is frequently used, but sometimes a log scale is used here, also. It is a representation of the number of alternating stress-cycles a material can sustain without failure at different maximum stresses.
Snell’s law – It defines the relationship between the angles of incidence and refraction of a ray of light as it passes from one medium to another, and the refractive indices of the two media. Mathematically, it is expressed as n1 sin(A1) = n2 sin(A2), where ‘n1’ and ‘n2’ are the refractive indices of the first and second media, respectively, and ‘A1’ and ‘A2’ are the angles of incidence and refraction. The law explains why light bends when it enters a different material, such as air to water, and is a fundamental principle in optics used for ray tracing and understanding the behavior of light.
SnMo6S8 (SMS) – It is tin molybdenum sulphide. It is is a type of Chevrel phase material, a class of compounds known for their superconducting properties. Super-conductors are materials which show zero electrical resistance and expel magnetic fields below a certain temperature, known as the critical temperature. SnMo6S8 is a specific example of a super-conducting material, belonging to the broader family of Chevrel phases (MxMo6S8).
Snort valve – It is a butterfly valve which installed in the cold blast line main before the stove normally located near the blast furnace. It is used for reducing or completely stopping the air blast to the blast furnace without stopping the operation of the blower. The valve is opened when it is necessary to decrease the blast pressure rapidly. This discharges the cold blast air to the atmosphere and keeps a positive pressure on the cold blast line so that the gas from the furnace cannot travel back to the blower. Because of rapid discharge of the air when the valve is opened, it is to be equipped with a muffler to control the noise level. The excess air is blown away through a blow off device which is mechanically interlinked with the main valve for proportionate opening / closing.
Snub idler – It consists of versatile rollers strategically used to augment the arc of contact between the conveyor belt and the drive pulley. These idlers play a pivotal role in improving traction and minimizing potential slippage. Regular inspections become indispensable to validate the optimal alignment and performance of snub idlers.
Snub pulley – It is a specialized pulley which is intricately designed to amplify the wrap angle of the conveyor belt, considerably improving traction and grip. Regular checks are vital to ascertain precise snub pulley alignment, mitigating the risk of belt slippage and ensuring consistent operational reliability.
Soak cleaning – It is the immersion cleaning without electrolysis.
Soaking – In heat treating of metals, it consists of prolonged holding at a selected temperature to effect homogenization of structure or composition.
Soaking furnace – It is a type of reheating furnace. It is a crucial part of the thin slab casting and rolling process. In this context, a soaking furnace is a type of furnace which is used to heat and homogenize the temperature of steel thin slabs (typically 60 millimeters to 75 millimeters thick) before they are rolled into thin strips or plates. This process ensures the slabs are at the correct temperature for deformation and proper microstructure development. Thin slab casting and rolling is a high-speed process where thin slabs are continuously cast and then immediately rolled without intermediate cooling or reheating.
Soaking pit – It is a type of pit-type reheating furnace mainly used for heating steel ingots before like hot rolling in blooming mill or slabbing mill. It ensures a uniform temperature distribution within the ingot before it is rolled. Soaking furnaces can also be used for heat preservation of steel ingots.
Soaking zone – It refers to a specific period, zone, or stage where the heated metal is held at a constant, controlled temperature for a pre-determined duration. This allows the internal structure of the metal to stabilize and reach uniform temperatures, especially after a heating phase.
Soap – In grease lubrication, soap refers to a metal salt of a fatty acid, which is a common thickening agent in lubricating greases. Grease is a semi-solid lubricant consisting of a liquid lubricant (oil) and a thickener, and soaps, along with other materials like clay, are frequently used as thickeners. These soaps help the oil hold its consistency and improve its lubricating properties. Soaps, like those made from lithium, calcium, or sodium, are the primary type of thickener used in greases. They act by forming a gel-like network that entraps the oil, giving the grease its semi-solid consistency.
Soap bubble test – It is also known as a bubble test or bubble leak test. It is a simple method for detecting leaks in sealed systems or components. It involves applying a soapy solution to the area suspected of having a leak and observing for the formation of bubbles, which indicates the presence of escaping gas or fluid. This method is particularly useful for identifying leaks in packaging, equipment, and other systems where leaks can compromise their functionality or safety.
Soap lubrication – It refers to the use of soap (or soap-based materials) to reduce friction and wear between moving surfaces. It is a common method used in several applications, from cleaning and lubricating in industry.
Soapstone – It is a soft powder or stone, basically hydrated magnesium silicate, having a soapy feel. It is used to dust the surface of unvulcanized rubber compounds. It keep them from sticking together. It is similar to talc.
Social capital – It consists of the social resources upon which people draw in pursuit of livelihoods (i.e., networks, membership of groups, relationships of trust, and access to wider institutions of society etc.).
Social costs – It is the costs of a product which are borne by society at large. An example is the cost of emissions resulting from extraction, processing, using, and disposing of a material or product.
Social vulnerability: Social vulnerability is one dimension of vulnerability to multiple stressors and shocks, including natural hazards. Social vulnerability refers to the inability of people, organizations, and societies to withstand adverse impacts from multiple stressors to which they are exposed. These impacts are due in part to characteristics inherent in social interactions, institutions and systems of cultural values.
Socio‑economic and health environment – Under this included are (i) collection of demographic and related socio-economic data, (ii) collection of epidemiological data, including studies on prominent endemic diseases (such as fluorosis, malaria, ffilariasis, and malnutrition etc.) and sickness rates among the population within the impact zone, (iii) projection of anticipated changes in the socio-economic and health due to the steel project and related activities including traffic congestion and description of measures to minimize adverse impacts, (iv) assessment of impact on significant historical, cultural and archaeological sites/places in the area, (v) assessment of economic benefits arising out of the project, and assessment of rehabilitation requirements with special emphasis on scheduled areas, if any.
Socio-economic assessment (SEA) – It is also known as socio-economic impact assessment (SEIA). It is a systematic process used to evaluate the social and economic consequences of a project, policy, or programme on a community or society. It aims to identify and analyze both the positive and negative impacts, helping to inform decision-making and promote sustainable development. It includes (i) impact on the local community including demographic changes, (ii) impact on economic status, (iii) impact on human health, and (iv) impact of increased traffic.
Socio-economic vulnerability – It is an aggregate measure of human welfare which integrates environmental, social, economic, and political exposure to a range of harmful perturbations.
Socio natural hazard – It is the phenomenon of increased occurrence of certain geophysical and hydro-meteorological hazard events, such as landslides, flooding, land subsidence and drought which arise from the interaction of natural hazards with overexploited or degraded land and environmental resources. Socio-natural hazards can be reduced and avoided through wise management of land and environmental resources.
Socket – It is also known as an electrical outlet or receptacle. It is a device which provides a connection point for electrical devices to receive power from an electrical system. It is the interface where a person plug in the cord and plug of an appliance, allowing electricity to flow from the power source to the device.
Socket wrench – It is also called socket spanner. It is a type of spanner or wrench which uses a closed socket format, rather than a typical open wrench / spanner to turn a fastener, typically in the form of a nut or bolt.
Socket weld flange – It is similar to slip-on flange, except it has a bore and counter bore. The counter bore allows the pipe to fit into the socket / counter bore. The bore of the flange is the same diameter as the inside of the pipe. Since the bore of the pipe and that of the flange is the same the flange provides good flow characteristics. Socket weld flanges are frequently used on high pressure, hazardous duties but their usage is usually limited to a nominal pipe size of 40 millimeters. The pipe is fillet welded to the hub of the socket weld flange. Radiography is not practical on the fillet weld and correct fit-up and welding is therefore crucial. The fillet weld is normally inspected by magnetic particle inspection or dry particle inspection.
Soda – It is sodium carbonate. Soda (or alternatively potash) is normally used as the alkali ingredient of glass. It serves as a flux to reduce the fusion point of the silica when the batch is melted.
Soda ash – It is sodium carbonate (Na2CO3). It is the main source of sodium oxide (Na2O), or ‘soda’. This anhydrous, white powder is added to the glass batch, with sodium oxide becoming part of the glass and carbon di-oxide being released.
Soda-lime glass – It is the most common type of industrially produced glass. A typical soda-lime glass is composed of silica (71 % to 75 %), soda (12 % to 16 %) and lime (10 % to 15 %), plus small quantities of other materials to provide particular properties such as colour.
Sodalite – It is a blue- to colourless tectosilicate mineral with the chemical formula Na4Al3(SiO4)3Cl. It belongs to the sodalite group, a family of feldspathoid minerals, and is characterized by its cage-like crystal structure. Found in basic igneous rocks, sodalite is valued for its royal blue variety as a gemstone and has a Mohs hardness of 5.5 to 6.
Soderberg electrode – It is a continuously self-baking electrode used in submerged arc furnaces for processes like ferroalloy and calcium carbide production. It is essentially a steel casing filled with a carbon-based paste (normally calcined carbon aggregates and coal tar pitch) which is continuously added and baked as it is consumed by the furnace.
Sodium (Na) – It is a chemical element having atomic number 11. It is a soft, silvery-white, highly reactive metal. It is an alkali metal, being in group 1 of the periodic table. Its only stable isotope is 23Na. The free metal does not occur in nature and is to be prepared from compounds. Sodium is the sixth most abundant element in the earth’s crust and exists in several minerals such as feldspars, sodalite, and halite (NaCl). Several salts of sodium are highly water-soluble. Sodium ions have been leached by the action of water from the earth’s minerals over eons, and hence sodium and chlorine are the most common dissolved elements by weight in the oceans.
Sodium-air batteries – These consist of a type of metal-air battery which uses sodium as the negative electrode and oxygen from atmospheric air in the porous positive electrode, offering potential advantages such as easier reversibility of cell reactions compared to lithium-air batteries.
Sodium bi-sulphate (SBS) – It is a compound which form during the injection of sodium-based reagents into flue gas, particularly when sodium is introduced in molar ratios close to 1:1 with sulphur tri-oxide (SO3), and is recognized for its sticky characteristics similar to ammonium bi-sulphite.
Sodium bi-sulphite – It is sodium hydrogen sulphite. It is a white, crystalline chemical mixture with the chemical formula NaHSO3. It is used as an antioxidant, and reducing agent in industrial applications, such as in water treatment and bio-chemical engineering to maintain anaerobic conditions. It functions by inhibiting micro-organisms and preventing oxidative corrosion. It is synthesized by treating a suitable base with sulphur di-oxide and is known for its slight sulphur di-oxide odour.
Sodium carbonate – It is the inorganic compound with the formula Na2CO3 and its several hydrates. All forms are white, odourless, water-soluble salts which yield alkaline solutions in water. It has been a popular agent for the desulphurization of hot metal. Sodium carbonate has been popular because of its easy application method. However, there have been considerable problems associated with the use of the sodium carbonate. Sodium carbonate has a melting temperature of around 851 deg C. It is stable until 1,200 deg C, which is lower than the temperature of the hot metal. So once sodium carbonate is in contact with the hot metal, it decomposes to Na2O (sodium oxide) and CO2 (carbon-di oxide) as per the equation Na2CO3 = Na2O + CO2. Na2O can be reduced by dissolved carbon into sodium (Na) gas.
Sodium cyanide – It is a chemical which is used in the milling of gold ores to dissolve gold and silver.
Sodium poly-acrylate – It is a super-absorbent polymer known for its remarkable ability to absorb and retain large amounts of liquid relative to its own mass. It is the sodium salt of poly-acrylic acid.
Sodium silicate – It is also known as water glass. It is a chemical compound composed of sodium and silicon oxides. It is a versatile substance with several industrial applications because of its adhesive, binding, and cleansing properties. It is normally used in detergents, and concrete.
Sodium sulphate (Na2SO4) – It is the sodium salt of sulphuric acid, appearing as a white crystalline solid, either anhydrous (water-free) or as a decahydrate (Na2SO4.10H2O, known as Glauber’s salt).
Soft annealing – It is a heat treatment process used to soften metallic materials, making them easier to work with and process, particularly for operations like shaping, forming, or machining. It involves heating the material to a specific temperature, holding it there for a period, and then cooling it slowly. This process reduces hardness and increases ductility, improving the material’s workability.
Soft arc – In arc welding, a soft arc refers to an arc with lower voltage and potentially less penetration into the weld joint compared to a ‘stiff’ arc. It is characterized by a more gentle, less forceful arc, frequently preferred for specific welding techniques and materials.
Softening – It is the act of reducing scale forming calcium and magnesium impurities from water.
Softening process – In industrial water treatment, it refers to the removal of those dissolved salts from water which makes the water hard. Softening of water is one approach to prevent scale build up in cooling systems.
Softening range – It is the range of temperatures in which a plastic changes from a rigid to a soft state. Actual values depend on the test method. Sometimes, it is erroneously referred to as softening point.
Softening temperature – It refers to the point at which the coal, when heated, transitions from a solid state to a more pliable, plastic-like state. This softening process is a crucial stage in coal coking, where coal is converted into coke, a solid fuel used in metallurgy and other applications. The softening temperature is influenced by factors like the coal type, heating rate, and surrounding environment.
Soft-faced hammer or mallet – It is a hammer which is designed to offer driving force without damaging surfaces. They also reduce the force transmitted back to the arm or hand of the user, by temporarily deforming more than a metal hammer does.
Soft iron core – It is a magnetic core typically used in inductors and generators, designed to generate and guide magnetic flux while minimizing eddy-current losses through the use of thin laminations of electrical steel.
Soft magnetic material – It is a ferro-magnetic alloy which becomes magnetized readily upon application of a field and which returns to practically a non-magnetic condition when the field is removed. It is an alloy with the properties of high magnetic permeability, low coercive force, and low magnetic hysteresis loss. Examples are sintered pure iron, or iron-3 % silicon alloy.
Soft materials – These are materials which can be easily deformed or structurally altered by thermal fluctuations or relatively small external forces. These materials are typically characterized by their ability to change shape or flow under stress, and they show a complex interplay between solid-like and liquid-like behaviour.
Soft matter – It refers to materials which are easily deformed by thermal fluctuations or small forces, exhibiting properties between solids and liquids. These materials are composed of mesoscopic particles, typically larger than individual molecules but smaller than macroscopic objects, and are held together by weak forces. Common examples include polymers, colloids, foams, and gels.
Soft particles – These are materials, frequently at a mesoscopic scale, which can be easily deformed or structurally altered by thermal or mechanical forces, and are frequently characterized by their ability to reconfigure their internal structure. They are typically distinguished from ‘hard particles’ by their ability to undergo large deformations, frequently without fracturing. Examples include colloids, polymers, gels, granular materials, and bio-colloids.
Soft solder – It is a non-standard term for solder.
Soft soldering – The preferred term is soldering.
Soft start – It is an ingenious mechanism ensuring a gradual acceleration of conveyor speed during the startup phase, mitigating stress and wear on components. Continuous monitoring is essential to preserve the efficacy of soft start systems, preventing abrupt starts and contributing to prolonged conveyor lifespan.
Soft temper – It is also called dead soft temper. It is a temper of non-ferrous alloys and some ferrous alloys corresponding to the condition of minimum hardness and tensile strength produced by full annealing.
Software – It is the set of instructions and data which direct a computer system.
Software development – It is the process of designing and implementing a software solution to satisfy a user. The process is more encompassing than programming, writing code, in that it includes conceiving the goal, evaluating feasibility, analyzing requirements, design, testing and release. The process is part of software engineering which also includes organizational management, project management, configuration management and other aspects. Software development involves several skills and job specializations including programming, testing, documentation, graphic design, user support, and marketing, It also involves several tools including: compiler, integrated development environment (IDE), version control, computer-aided software engineering, and word processor.
Software engineering – It is the profession of designing software systems to meet specified performance requirements.
Software testing – It is a process of verifying and validating whether the software product or application is working as expected or not. It can provide objective, independent information about the quality of software and the risk of its failure to a user or sponsor.
Soft water – It is that water which contains low concentrations of ions and in particular is low in ions of calcium and magnesium. It is the water which contains little or no calcium or magnesium salts, or water from which scale forming impurities have been removed or reduced. It is that water which is free from dissolved salts of such metals as calcium (Ca), magnesium (Mg), or / and iron (Fe) which form insoluble deposits which appear as scale in the pipe lines and the water-cooling elements. Soft water is used in steel plants in closed loop cooling circuits. Soft water has 0 parts per million (ppm) to 17 parts per million of hardness imparting elements. Because of the comparative absence of these minerals, soft water has increased sodium content. The term is used to describe water that has been produced by a water softening process. Soft water may also contain elevated levels of sodium and bicarbonate ions. Soft water produces no calcium deposits in water heating systems and indirect water-cooling system.
Soil – It is a natural body, a dynamic mixture of solid (minerals and organic matter), liquid, and gases, which forms the earth’s surface layer and supports plant growth. It is characterized by distinct layers (horizons) and its ability to support rooted plants. Soil is also the undesirable material on a surface which is not an integral part of the surface. Oil, grease, and dirt can be soil, while a decarburized skin and excess hard chromium are not soils. Loose scale is soil, while hard scale is an integral part of the surface and, hence, not soil.
Soil conditioner – It is a substance or product added to soil to improve its physical properties, such as structure, aeration, water-holding capacity, and nutrient availability, ultimately improving plant growth and health.
Soil engineering – It is a branch of civil engineering focused on the practical application of soil mechanics principles to design, construction, and maintenance of earth structures and foundations. It involves analyzing soil properties, assessing soil behaviour under different conditions, and developing solutions for stability and performance in construction projects.
Soil erosion – Erosion is the process of weathering and transport of solids (sediment, soil, rock and other particles) in the natural environment or their source and deposits them elsewhere. It normally occurs because of the transport by wind, water or ice, by down-slope creep of soil and other material under the force of gravity, or by living organisms, such as burrowing animals in the case of bio-erosion.
Soil mechanics – It is a branch of geotechnical engineering which studies the physical and mechanical properties of soils, such as their composition, structure, strength, stability, and behaviour under different conditions and loads. It applies principles of mechanics, physics, and hydraulics to analyze how soils perform as an engineering material in applications like foundations, retaining walls, and tunnels.
Soil moisture – It is the water stored in or at the land surface and available for evaporation.
Soil morphology – It refers to the study and description of a soil’s physical characteristics, including its structure, texture, colour, and arrangement in horizons. It essentially describes the form, arrangement, and composition of a soil as observed in the field and sometimes in the laboratory.
Soil-structure interaction (SSI) – Majority of the civil engineering structures involve some type of structural element with direct contact with ground. When the external forces, such as earthquakes, act on these systems, neither the structural displacements nor the ground displacements, are independent of each other. The process in which the response of the soil influences the motion of the structure and the motion of the structure influences the response of the soil is termed as soil-structure interaction. Conventional structural design methods neglect the soil-structure interaction effects. Neglecting soil-structure interaction is reasonable for light structures in relatively stiff soil such as low-rise buildings and simple rigid retaining walls. The effect of soil-structure interaction, however, becomes prominent for heavy structures resting on relatively soft soils for example nuclear power plants, high-rise buildings and elevated-highways on soft soil.
Soil waste – It is an unneeded or unusable soil from construction, demolition or renovation projects.
Sol – It is a suspension of solid particles in a liquid. Artificial examples include sol-gels.
Solar cell – It is a photo-voltaic cell, which is used to produce power from sunlight. It is an electronic device which converts the energy of light directly into electricity by means of the photo-voltaic (PV) effect. It is a type of photo-electric cell, a device whose electrical characteristics (such as current, or ‘resistance) vary when it is exposed to light. Individual solar cell devices are frequently the electrical building blocks of photo-voltaic modules, known colloquially as solar panels. Almost all commercial photo-voltaic cells consist of crystalline silicon. Cadmium telluride thin-film solar cells account for the remainder. The common single-junction silicon solar cell can produce a maximum open-circuit voltage of around 0.5 volts to 0.6 volts. Photo-voltaic cells can operate under sunlight or artificial light. In addition to producing solar power, they can be used as a photo-detector (e.g., infrared detectors), to detect light or other electro-magnetic radiation near the visible light range, it also to measure light intensity.
Solar energy – It is useful energy extracted by some means from sunlight. It is the radiant light and heat from the Sun, which is captured and converted into usable forms of energy like electricity and heat using different technologies such as photo-voltaic cells and solar thermal systems. Solar energy engineering focuses on designing, developing, and optimizing these systems to make the conversion of sunlight to usable energy efficient and sustainable.
Solar farms – These are large-scale installations which generate electricity from sunlight, utilizing technologies such as photo-voltaic (PV) systems or concentrating solar power (CSP) to convert solar energy into usable power.
Solar micro-inverter – It is an inverter suitable for use with a single solar panel.
Solar panels – They are also called solar modules. They are designed to supply electric power at a certain voltage (say 12 volts), but the current they produce is directly dependent on the incident light. As of now, it is clear that photo-voltaic modules provide direct current electric power.
Solar photo-voltaic modules – These convert solar radiation directly into electricity through the photovoltaic effect in a silent and clean process which needs no moving parts. The photovoltaic effect is a semi-conductor effect whereby solar radiation falling onto the semiconductor photovoltaic cells generates electron movement. The output from a solar photovoltaic cell is direct current power. A photo-voltaic power plant contains several cells connected together in modules and several modules connected together in strings to produce the needed direct current power output. Modules can be connected together in a series to produce a string of modules. When connected in a series, the voltage increases. Strings of modules connected in parallel increase the current output.
Solar photo=voltaic power – Certain materials, like silicon, naturally release electrons when they are exposed to light, and these electrons can then be harnessed to produce an electric current. When these materials are exposed-to light, they absorb photons and release free electrons. This phenomenon is called the photo-voltaic (PV) effect. Photo-voltaic is a method for the direct conversion of light into electricity. Solar photovoltaic effect is used to generate electrical power by converting solar energy radiation into direct current (DC) electric power. For this purpose, semiconductors are used since they show the photo-voltaic effect. Solar photovoltaic power is a renewable as well as sustainable energy source. Conversion of the solar energy into electrical energy by photo-voltaic power plants is the most recognized way to utilize solar energy. Photo-voltaic power plants (cell, module, network) need very little maintenance. Main components of a solar photo-voltaic stem are solar panels, direct current-direct current converter, MPPT (maximum power point tracking), charge controller, battery for storage, direct current-alternating current converter (inverter) and load to be fed. As per the power requirement, multiple photo-voltaic modules can be electrically connected together to form a photovoltaic array.
Solar radiation – Energy from the Sun comes to the earth in the form of solar radiation. It allows the production of electric power in the photo-voltaic (PV) power plants. Under optimal conditions, the earth’s surface can get 1,000 watts per square metre (W/sq-m), while the actual value depends on the location, i.e., latitude, climatological location parameters such as frequency of cloud cover and haze, and air pressure etc. Irradiation is the average density of the radiant solar radiation power, and is equal to the ratio of the solar radiation power and surface of the plane perpendicular to the direction of this radiation. Radiation represents the quantity of solar radiation which is radiated on the unit surface at a given time (watt hour per square metre, W.h/sq-m) or (joule per square metre, J/sq-m). Besides expressing it in hourly values, it is frequently expressed as daily, monthly, or yearly radiation, depending on the time interval. The solar radiation weakens on its way through the earth’s atmosphere because of the interaction with gases and vapours in the atmosphere and arrives at the earth’s surface as direct and diffused. Direct sunlight comes directly from the sun, while scattered or diffused radiation reaches the earth from all directions. The total radiation consists of direct and diffused radiation.
Solar reflectance – It is a measure of the ability of a surface material to reflect sunlight, including the visible, infrared and ultraviolet wavelengths, on a scale of 0 to 1. Solar reflectance is also called albedo. White paint (titanium dioxide) is defined to have a solar reflectance of 1 while black paint has a solar reflectance of 0.
Sold – It is that material which has a tendency to resist any attempt to change its size or shape.
Solder – It is a filler metal which is used in soldering that has a liquidus not exceeding 450 deg C.
Soldered joints – These are connections formed by joining components with a lower-melting-point alloy without melting the parent metal, typically utilizing a tin alloy in soft soldering at temperatures around 250 deg C. These joints need clean surfaces and appropriate fluxes to ensure adequate mechanical strength and to mitigate corrosion risks.
Solderability – It is the relative ease and speed with which a surface is wetted by molten solder.
Solder embrittlement – It is the reduction in mechanical properties of a metal as a result of local penetration of solder along grain boundaries.
Soldering – It is a group of processes which join metals by heating them to a suitable temperature below the solidus of the base metals and applying a filler metal having a liquidus not exceeding 450 deg C. Molten filler metal is distributed between the closely fitted surfaces of the joint by capillary action. It is a critical process in the assembly of most electronic devices.
Soldering flux – It is the material which is used to prevent the formation of, or to dissolve and facilitate removal of, oxides and other undesirable substances.
Soldering gun – It is an electrical soldering iron with a pistol grip and a quick heating, relatively small bit.
Soldering iron – It is a soldering tool having an internally or externally heated metal bit normally made of copper.
Solder interface – It is the interface between filler metal and base metal in a soldered joint.
Soldiers – These are wooden pegs used to reinforce a body of sand or hold it in place.
Solenoid – It is a coil of wire used to create a magnetic field. It is frequently a device with a ferro-magnetic plunger which moves when the coil is energized.
Solenoid actuators – These are devices which convert electrical energy into mechanical motion, frequently used to switch valves from open to closed positions in several applications, including batch processing.
Solenoid valve – It is an electro-mechanical device which controls the flow of liquids or gases by using an electro-magnet to open or close a valve. When an electric current is applied to the solenoid coil, it creates a magnetic field which moves a plunger or armature, opening or closing the valve and hence controlling the flow.
Sole plates – These are baseplates which support machinery, typically placed on a foundation and levelled before filling any voids with grout material. Pre-grouted, epoxy-filled sole plates are considered superior for reliability in user plants.
Sol-gel process – It is a chemical technique for creating nano-materials and coatings, beginning with a sol (a colloidal suspension) which transforms into a gel (a solid-like network) through hydrolysis and poly-condensation reactions of molecular precursors, typically metal alkoxides. This process allows for the creation of different forms, including powders, thin films, and porous materials, by controlling factors like precursor chemistry and drying methods.
Solid – It is one of the four fundamental states of matter, characterized by relatively low-energy particles packed closely together in rigid structures with definite shape and volume.
Solid additives – In grease lubrication, these are solid materials, like graphite or molybdenum di-sulphide, added to grease to improve its performance, especially in extreme conditions. These additives reduce friction, prevent wear, and help separate moving surfaces when the base oil alone is not sufficient.
Solid bond – It refers to a physical connection or interaction which holds particles together in a solid material, classified by the type of chemical bond involved, such as ionic, covalent (network covalent or covalent molecular), or metallic bonds. Different solid bonds lead to distinct properties like hardness, electrical conductivity, and melting points, allowing solids to be categorized into different types like ionic, molecular, covalent, and metallic solids.
Solid contraction – It is the shrinkage or contraction as the metal cools from the solidifying temperature to room temperature.
Solid density – It refers to the mass of a substance per unit volume. It is a fundamental property which describes how tightly packed the matter of a solid is, and it is typically expressed in units like grams per cubic centimeter.
Solid-film lubrication – It is the lubrication by application of solid lubricants.
Solid fuel – It is a fuel which is in solid form. It can be burned to release energy through combustion, typically providing heat and light. These materials remain solid at room temperature and include natural substances like wood and coal, as well as manufactured forms such as charcoal, coke, and wood pellets.
Solid-gas reaction – It is a heterogeneous chemical reaction which occurs at the boundary between a solid and a gas, involving the interaction between a gaseous reactant and a solid reactant to produce solid or gaseous products. These reactions are common in processes like sorption, corrosion, and metal production, and they need the transfer of mass and heat between the gas phase and the solid phase for the reaction to proceed.
Solidification – It is the change in state from liquid to solid upon cooling through the melting temperature or melting range.
Solidification cracking – It is also known as hot cracking or hot tearing. It is a type of defect which occurs during the solidification of metals, frequently in welding and casting processes. It happens when shrinkage strains or thermal stresses develop during solidification, causing cracks to form, especially in areas where liquid metal is insufficient to fill the gaps.
Solidification front -It refers to the interface during the solidification process where local equilibrium at the solid-liquid interface can be assumed to establish instantaneously, enabling the prediction of micro-segregation and phase distribution in the resulting micro-structure.
Solidification range – Only pure metals solidify or freeze at one definite temperature. Alloys contain different constituents which solidify at different temperatures. The different temperatures from that of the first constituent to solidify to that of the last to constituent to freeze is called the solidification range.
Solidification range is the temperature between the liquidus and the solidus.
Solidification shrinkage – It is the reduction in volume which occurs when a material, typically a molten metal, transitions from a liquid to a solid state, leading to a decrease in overall dimensions. It is a critical phenomenon in processes like casting and welding, since it can cause internal voids (porosity), shrinkage cavities, and dimensional inaccuracies if the mould or casting process is not designed to account for this inevitable contraction.
Solidification shrinkage crack – It is a crack which forms, normally at high temperature, because of the internal (shrinkage) stresses that develop during solidification of a metal casting. It is also termed hot crack.
Solidification structure – It refers to the arrangement and characteristics of the solid phases formed during the transformation of a liquid or gas into a solid. This structure is influenced by several factors like cooling rate, composition of the material, and the presence of impurities, ultimately affecting the final material’s properties.
Solidification temperature of a mould flux – It is the temperature at which, on cooling at a defined rate, there is a sudden change in the shape of the viscosity versus temperature curve and at which the mould flux starts to solidify.
Solidifying contraction – It is the shrinkage or contraction as metal solidifies.
Solid lubricant – It is a solid used as a powder or thin film on a surface to provide protection from damage during relative movement and to reduce friction and wear. Solid lubricants are rarely used directly. Normally, they are added with other lubricants to increase some of its properties. Some examples of solid lubricants are graphite, molybdenum di-sulphide, mica, talc or soap, lead carbonate, and wax etc.
Solid mechanics – It is the branch of continuum mechanics which studies the behaviour of solid materials, especially their motion and deformation under the action of forces, temperature changes phase changes, and other external or internal agents. Solid mechanics is fundamental for civil, nuclear, and mechanical engineering, for geology, and for several branches of physics and chemistry such as materials science.
Solid metal embrittlement – It is the occurrence of embrittlement in a material below the melting point of the embrittling species.
Solid metal-induced embrittlement (SMIE) – It is a phenomenon where the ductility or fracture strength of a normally ductile material is reduced by contact with a solid metal, especially one with a lower melting point. It is the embrittlement caused by diffusion of metal into the base material. This embrittlement occurs under tensile stress.
Solid modelling – It is a consistent set of principles for mathematical and computer modelling of three-dimensional shapes (solids). Solid modelling is distinguished within the broader related areas of geometric modelling and computer graphics, such as 3D modelling, by its emphasis on physical fidelity. Together, the principles of geometric and solid modeling form the foundation of 3D-computer-aided design, and in general, support the creation, exchange, visualization, animation, interrogation, and annotation of digital models of physical objects. The use of solid modelling techniques allows for the automation process of several difficult engineering calculations which are carried out as a part of the design process. Simulation, planning, and verification of processes such as machining and assembly are one of the main catalysts for the development of solid modelling. More recently, the range of supported manufacturing applications has been largely expanded to include sheet metal manufacturing, injection moulding, welding, pipe routing, etc. Beyond traditional manufacturing, solid modelling techniques serve as the foundation for rapid prototyping, digital data archival and reverse engineering by reconstructing solids from sampled points on physical objects, mechanical analysis using finite elements. motion planning and numerical control (NC) path verification, kinematic and dynamic analysis of mechanisms, and so on.
Solid oxide electrolyzer process – Green hydrogen can also be produced using solid oxide electrolysis cells or anion exchange membrane electrolysis. The process uses the latest generation of electrolyzer cell which is still in the demonstration stage but has great future prospects. This technology produces hydrogen through high-temperature electrolysis of steam. It offers high efficiency at low cost. Solid oxide electrolyzers are typically operated for high temperature water electrolysis or steam electrolysis, where a larger portion of the energy for splitting water molecules is provided in the form of heat. The process reduces the electric power consumption, resulting in a higher stack electrical efficiency but not necessarily a higher overall energy efficiency.
Solid oxide electrolyzers – These electrolyzers use a solid ceramic material as the electrolyte which selectively conducts negatively charged oxygen ions (O2-) at elevated temperatures, generate hydrogen in a slightly different way. Steam at the cathode combines with electrons from the external circuit to form hydrogen gas and negatively charged oxygen ions. The oxygen ions pass through the solid ceramic membrane and react at the anode to form oxygen gas and generate electrons for the external circuit. Solid oxide electrolyzers must operate at temperatures high enough for the solid oxide membranes to function properly (around 700 deg C to 800 deg C).
Solid oxide fuel cell (SOFC) – It is an electrochemical device which generates electricity by directly converting fuel into energy through an electro-chemical reaction. It uses a solid ceramic material as its electrolyte, which allows oxygen ions to conduct through it from the cathode to the anode. At the anode, the oxygen ions react with a fuel, such as hydrogen or carbon mono-oxide, producing water and releasing electrons. These electrons then flow through an external circuit, creating an electric current, and return to the cathode.
Solid particle erosion (SPE) – It is a type of material degradation caused by the repeated impact of solid particles on a surface, leading to material removal. This process is common in various applications where particles are carried by fluids or gases, such as in gas turbine engines, pipelines, and high-speed vehicles.
Solid particle erosion wear testing – It is a method to evaluate how a material degrades because of the impact of solid particles. This type of wear is common in engineering applications where components are exposed to high-speed particles, such as sand or dust, carried by a fluid. The testing process typically involves exposing a sample material to a stream of erosive particles and measuring the resulting material loss.
Solid-phase extraction (SPE) – It is a solid-liquid extractive technique, by which compounds that are dissolved or suspended in a liquid mixture are separated, isolated or purified, from other compounds in this mixture, as per their physical and chemical properties. Analytical laboratories use solid phase extraction to concentrate and purify samples for analysis. Solid phase extraction can be used to isolate analytes of interest from a wide variety of matrices.
Solid phase processing – It refers to a group of techniques where chemical reactions or material transformations occur while keeping one or more reactants in a solid state. This approach is frequently used to simplify reactions, improve efficiency, or enable specific material properties.
Solid-phase synthesis – It is a method in which molecules are covalently bound on a solid support material and synthesized step-by-step in a single reaction vessel utilizing selective protecting group chemistry. Benefits compared with normal synthesis in a liquid state include (i) high efficiency and throughput, and (ii) increased simplicity and speed. The reaction can be driven to completion and high yields through the use of excess reagent. In this method, building blocks are protected at all reactive functional groups. The order of functional group reactions can be controlled by the order of deprotection.
Solid polystyrene (PS) – It is a hard, transparent, and rigid thermoplastic polymer made from styrene monomers. It is a widely used plastic, known for its versatility and ability to be moulded into different shapes. In its solid form, it is brittle and can be either clear or coloured.
Solid-projection welding – It needs that the projection be forged onto one of the two components. Then, during resistance welding, the contact point and the projection itself experience preferential heating. In this case, the projection cannot simply collapse, as it does in embossed-projection welding. Rather, the projection collapses by penetrating the opposing material and by extrusion to the periphery. When compared with embossed-projection welding, the resulting joints are solid-state, rather than fusion, welds. The actual joints are caused by a combination of material forging and diffusion bonding, much like they are in resistance butt and flash butt welding.
Solid-projection welds – These welds are essentially strain-assisted diffusion bonds. Because the projections typically collapse at very high temperatures (normally, within several hundred deg C of the melting point), diffusion bonding can occur within very limited available time (usually, less than 1 second). Not surprisingly, some of the material-related factors which affect diffusion bonding also affect solid-projection welding. The strength-temperature relationship also affects projection weldability. Materials which maintain their strengths at relatively high temperatures permit substantial heating to occur before projection collapse. This heat then becomes available to promote diffusion after projection collapse. Premature collapse results in lower temperatures in which diffusion can occur and in reduced current density, which prohibits further resistance heating. Bulk resistivity also plays a role in projection welding, but to a lesser degree. Increased bulk resistivity can reduce the effectiveness of the projection as a current concentrator. With increasing bulk resistivity, the tendency is for delocalized heating and in general, rather than local, collapse of the projection. As a result, high-resistivity materials are more difficult to projection weld.
Solid shrinkage – It is the reduction in volume of metal from the solidus to room temperature.
Solid solution – It is a single, solid, homogeneous crystalline phase containing two or more chemical species. If alloying elements are retained in the lattice of the parent metal instead of forming a different phase they are said to be in solid solution. Alloys which that are multi-phase at room temperature can normally be made single phase by heating to a suitable temperature below the melting point, by holding at this temperature, then quenching in water, oil or cold air. The alloying element(s) have been taken into solid solution by the heating and retained there by the rapid cooling. They can be precipitated out by heating again, to a lower temperature, a process called ageing. The two stages are a useful heat treatment cycle for several alloys.
Solid solution strengthening – It is a type of alloying which can be used to improve the strength of a pure metal. The technique works by adding atoms of one element (the alloying element) to the crystalline lattice of another element (the base metal), forming a solid solution. The local non-uniformity in the lattice due to the alloying element makes plastic deformation more difficult by impeding dislocation motion through stress fields. In contrast, alloying beyond the solubility limit can form a second phase, leading to strengthening through other mechanisms (e.g., the precipitation of inter-metallic compounds).
Solids retention time (SRT) – It refers to the average time which solids, or activated sludge, spend in a treatment system. It is a crucial parameter in waste-water treatment, especially in processes like activated sludge systems, where the time the sludge remains in the system directly impacts biological treatment and the overall efficiency of removing pollutants.
Solid state – It consists of electronics which relies on current flow through crystalline lattices.
Solid state bonding – It is also known as solid-state diffusion bonding or solid-state welding. It is a joining process where two materials are joined without melting or adding filler materials. It relies on the interdiffusion of atoms at the interface of the materials, typically at high temperatures, to create a strong bond at an atomic level. This process involves applying pressure to the mating surfaces and heating them to a temperature range where atomic diffusion is significant, normally around 50 % to 90 % of the material’s absolute melting point.
Solid-state chemistry –It therefore has a strong overlap with solid-state physics, mineralogy, crystallography, ceramics, metallurgy, thermodynamics, materials scienc, and electronics with a focus on the synthesis of novel materials and their characterization. A diverse range of synthetic techniques, such as the ceramic method and chemical vapour deposition, make solid-state materials. Solids can be classified as crystalline or amorphous on basis of the nature of order present in the arrangement of their constituent particles. Their elemental compositions, micro-structures, and physical properties can be characterized through a variety of analytical methods.
Solid-state drive (SSD) – It is a data storage device which uses integrated circuits to store data persistently. Unlike traditional hard disk drives (HDDs) that use moving parts like spinning disks, solid-state drives have no mechanical components, making them faster, more durable, and more reliable.
Solid-state physics – It is that branch of physics which studies arrangements of atoms in fixed arrays. It is the study of rigid matter, or solids, through methods such as solid-state chemistry, quantum mechanics, crystallography, electro-magnetism, and metallurgy. It is the largest branch of condensed matter physics. Solid-state physics studies how the large-scale properties of solid materials result from their atomic-scale properties. Hence, solid-state physics forms a theoretical basis of materials science. Along with solid-state chemistry, it also has direct applications in the technology of transistors and semiconductors.
Solid-state sintering – It is a sintering procedure for compacts or loose powder aggregates during which no component melts.
Solid-state sensors – These are also known as the electronic IC (integrated circuit) temperature sensors. These are specialized integrated circuits used for sensing temperatures in the -55 deg C to 150 deg C range. The small solid-state sensor converts a temperature input into a proportional current output over a range of -55 deg C to 150 deg C. It is especially suited for PC (personal computer) boards or heat sink mounting for special temperature measurement and control applications where solid-state reliability, linearity, and accuracy are needed.
Solid-state transformer (SST) – It is a power electronic device which replaces traditional transformers by using power electronic converters and high-frequency transformers to achieve alternating current-alternating current power conversion. Basically, it is a high-tech alternative to conventional transformers, offering advantages like reduced size, improved controllability, and the ability to manage power flow more dynamically.
Solid-state transformations – It refer to changes within the solid state of a material, where its structure, composition, or properties alter without melting or becoming a gas. These transformations can be driven by factors like temperature, pressure, or chemical reactions, and involve processes like nucleation, growth, and the movement of interfaces between different phases.
Solid-state transformations in weldments – Solid-state transformations occurring in a weld are highly non-equilibrium in nature and differ distinctly from those experienced during casting, thermo-mechanical processing, and heat treatment. This discussion mainly focuses on the welding metallurgy of fusion welding of steels and attempt to highlight the fundamental principles which form the basis of several of the recent developments in steels and consumables for welding. Accordingly, examples are largely drawn from the well-known and relatively well-studied case of ferritic steel weldments to show the special physical metallurgical considerations brought about by the weld thermal cycles and by the welding environment.
Solid-state welding – It is a group of welding processes which join metals at temperatures essentially below the melting points of the base materials, without the addition of a brazing filler metal. Pressure may or may not be applied to the joint. Examples include cold welding, diffusion welding, forge welding, hot pressure welding, and roll welding.
Solidus – It is the highest temperature at which a metal or alloy is completely solid. In a phase diagram, the locus of points representing the temperatures at which different compositions stop freezing upon cooling or begin to melt upon heating.
Solidus line – On a phase diagram, it represents the temperatures at which a material, such as an alloy or mixture, is completely solid, or when it begins to melt on heating under equilibrium conditions. Below this line, only the solid phase is stable, while above it, both liquid and solid phases can coexist.
Solidus temperature – It is the highest temperature at which a material remains completely solid, marking the beginning of melting. It is the temperature below which a substance is entirely in a solid state and above which it starts to melt and become partially liquid. In essence, it is the melting point of a solid, but not necessarily the temperature at which the material is completely liquid.
Solid waste – It is also called solid pollutants. It refers to any discarded or unwanted materials, including garbage, trash, refuse, or any other discarded material that is solid, semi-solid, or contains gaseous material, resulting from industrial, commercial, or other human activities. It can be generated from different sources. solid wastes generated in industry can be broadly categorized as (i) process solid wastes, and (ii) non-process solid wastes. Examples of process solid wastes are slag, dust, sludge, scrap, refractories, scale, muck, and debris etc. Examples of non-process waste materials are rubber, packing materials, electric wires, plastics and glass, and office and canteen wastes, etc. Solid waste materials are usually generated in mixed condition which means that during generation, one solid waste material gets contaminated with other waste material. These waste materials are to be segregated for their recycling and reuse.
Solid waste disposal – It refers to the process of managing and disposing of discarded solid materials, encompassing collection, treatment, and final disposal, ensuring minimal environmental impact and public health risks.
Solid waste management – It is the systematic process of handling solid waste, from collection and transportation to treatment, recycling, and disposal, with the goal of minimizing environmental impact and public health risks. It involves planning, organizing, and implementing waste management programs to reduce the negative effects of waste on human health and the environment.
Solid-woven belt – This type of belt consists of a single ply of solid-woven fabric, normally impregnated and covered with poly-vinyl chloride (PVC) with relatively thin top and bottom covers. The surface of poly-vinyl chloride belts is frequently rough on purpose to aid in conveying on inclines, but the rough surface makes belt cleaning more difficult. The abrasion resistance of poly-vinyl chloride is lower than rubber, so some solid-woven belts are made with a combination of poly-vinyl chloride core and rubber covers.
Solubility – It is the property of a solid, liquid, or gaseous solute to dissolve in a solid, liquid, or gaseous solvent. It is typically expressed as the proportion of solute dissolved in the solvent in a fully saturated solution. It is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solubility of a substance in a specific solvent is normally measured as the concentration of the solute in a saturated solution, one in which no more solute can be dissolved. At this point, the two substances are said to be at the solubility equilibrium. For some solutes and solvents, there can be no such limit, in which case the two substances are said to be ‘miscible in all proportions’ (or just ‘miscible’). The solute can be a solid, a liquid, or a gas, while the solvent is normally solid or liquid. Both can be pure substances, or can themselves be solutions. Gases are always miscible in all proportions, except in very extreme situations, and a solid or liquid can be ‘dissolved’ in a gas only by passing into the gaseous state first.
Solubility limit – It is the maximum quantity of a solute which can dissolve in a given quantity of solvent at a specific temperature and pressure, resulting in a single-phase solution. Beyond this limit, no more solute can dissolve, and excess solute remains undissolved or form additional phases.
Solubility productKs – It refers to the equilibrium constant used to predict the formation and dissolution of precipitates based on factors like temperature, pH, and concentrations of reactants. It helps determine the maximum concentration of ions which can be present in a solution before a precipitate is formed. It is a measure of the solubility of an ionic solute, expressed as the arithmetic product of the concentrations of its ions in a fully saturated solution, with respect to the solute’s particular dissociation equilibria and the particular ions present. The solubility product is derived from and functions like the equilibrium constant of dissociation, though unlike an equilibrium constant it is not dimensionless. If the product of ionic concentrations in a solution exceeds the solubility product, then precipitation occurs.
Solubility product constant – It is the product of the activities of the ions in a saturated solution of a relatively insoluble salt, expressed in moles per 1,000 grams of solution. It is useful for evaluating how changes in the concentration of other components in the solution affect the concentrations of ions at saturation.
Soluble – A substance is soluble if it dissolves in certain fluids. The fluid (gas or liquid) which is present in excess, is called the solvent and the substance dissolved in it is called the solute. Solvent and solute both together form a solution.
Soluble corrosion inhibitors – These are substances which can be dissolved in a specific fluid and are added to mitigate corrosion by converting an active corrosion process into a passive one, particularly in hydro-carbon systems. They are selected based on their solubility or dispersibility in the fluids to be inhibited.
Soluble-gas atomization – It is a type of gas atomization. It involves using a gas dissolved in a liquid (e.g., water) to break up a molten metal stream into fine droplets, which then solidify into powder. This method differs from traditional gas atomization, which uses high-velocity gas jets directly on the molten metal.
Soluble oil – It is also known as emulsifiable oil or water-miscible coolant. It is a mineral oil containing additives which enable it to form a stable emulsion with water. It is a type of lubricating oil which can be mixed with water to form a stable emulsion. This emulsion provides both lubrication and cooling, making it suitable for many metal-working and other industrial applications. Soluble oils are used as cutting or grinding fluids.
Soluble salt – It is a type of salt which readily dissolves in water to form a solution, meaning it breaks down into its constituent ions and mixes uniformly with the water. Basically, it is a salt which can be dissolved in water to create a homogeneous mixture, where the salt is dispersed evenly throughout the water.
Solute – It is the part of a solution which is dissolved into the solvent, e.g., sodium chloride (NaCl) is the solute in a solution of saline water. It is the component of either a liquid or solid solution which is present to a lesser or minor extent.
Solute concentration – It refers to the quantity of a solute (the substance being dissolved) present within a specific amount of a solvent (the substance doing the dissolving) or a complete solution. It quantifies how much of the solute is dissolved, and can be expressed using different units, such as molarity (moles of solute per litre of solution), mass percent, or parts per million. A solution with a high solute concentration has a lot of dissolved solute substance, while a dilute solution has very little.
KspSolution – It is a homogeneous mixture made up of multiple substances normally referred to as solutes and solvents. It is a liquid, such as boiler water, containing dissolved substances.
Solution algorithm – t is a step-by-step procedure or a set of instructions designed to solve a specific problem or perform a task. It is a finite sequence of operations which, when followed in the prescribed order, leads to the desired outcome. Essentially, it is a blueprint or recipe for solving a problem, often used in computer science and other fields.
Solution annealing – It is also referred to as solution treating. It is a common heat-treatment process for stainless steels. The purpose of solution annealing is to dissolve any precipitates present in the material, and transform the material at the solution annealing temperature into a single-phase structure. At the end of the solution annealing process, the material is rapidly quenched down to room temperature to avoid any precipitation from occurring during cooling through lower temperature ranges. The single-phase solution annealed material is in a soft state after treatment. The solution annealing treatment is needed prior to age hardening / precipitation hardening. The single-phase microstructure created during solution annealing is needed prior to age hardening, so that only the precipitates formed during age hardening are present in the final product. The composition, size, and quantities of these precipitates formed during aging determine the final product’s hardness, strength, and mechanical properties after aging. It is critical that the structure be properly solution annealed prior to aging in order to meet all of these requirements.
Solution-diffusion mechanism – It is a transport process where both solute and solvent are dissolved on the membrane surface and diffuse separately through the membrane driven by concentration gradients and applied pressure. This mechanism is characterized by distinct rates of diffusion and solubility for the materials involved, and it has been effectively applied in various membrane processes such as gas separation and reverse osmosis.
Solution heat treatment – It means heating an alloy to a suitable temperature, holding at that temperature long enough to cause one or more constituents to enter into solid solution, and then cooling rapidly enough to hold these constituents in solution.
Solution potential – It is the electrode potential where half-cell reaction involves only the metal electrode and its ion.
Solution pump – It is a device which facilitates the movement of a solution between different pressure sections of a heat pump system, using mechanisms such as check valves and driven by high-pressure vapour, while mitigating issues like cavitation and seal challenges.
Solution techniques – These refer to methods used for applying metal ion solutions and reducing agents onto surfaces to form coatings, mainly on metals and plastics. These techniques include spraying and chemical conversion coating, improving properties such as corrosion prevention and lubrication.
Solution testing – It refers to the process of evaluating the functionality, performance, and overall suitability of a proposed solution, particularly in the context of software or complex systems. It involves testing the solution in a realistic environment to identify potential issues and ensure it meets the intended requirements before deployment.
Solution-treatment and aging (STA) – It is a heat treatment process mainly used for certain metallic alloys, particularly aluminum, to improve their strength and hardness. Solution treatment involves heating the alloy to a high temperature, holding it there to dissolve precipitates, and then rapidly cooling (quenching) it to retain these dissolved elements in a solid solution. Aging, also known as precipitation hardening, follows solution treatment. It involves heating the quenched alloy to a lower temperature for a specific time, allowing precipitates to form and strengthen the material.
Solution treatment and quenching – It is a heat treatment process where an alloy is heated to a temperature sufficient to dissolve its soluble phases, then rapidly cooled (quenched) to lock in a supersaturated solid solution. This process is frequently a preliminary step before further heat treatments, like precipitation hardening, to achieve specific material properties.
Solution velocity – It is the speed of a fluid moving past a metal surface, which influences corrosion rates by affecting concentration polarization and the metal’s passivation state. At low velocities, corrosion can be diffusion-controlled, whereas at high velocities, it can become reaction-controlled, with critical velocities determining the metal’s active or passive behaviour.
Solution strengthened alloys – These are metallic alloys which achieve increased strength through the dissolution of specific elements in the metal matrix, which improves workability and high creep rupture strength, frequently complemented by the presence of precipitates such as carbides and nitrides.
Solvated electron – It is a free electron in a solution, in which it behaves like an anion. An electron’s being solvated in a solution means it is bound by the solution. The notation for a solvated electron in formulas of chemical reactions is e-‘. Frequently, discussions of solvated electrons focus on their solutions in ammonia, which are stable for days, but solvated electrons also occur in water and several other solvents, in fact, in any solvent which mediates outer-sphere electron transfer. The solvated electron is responsible for a great deal of radiation chemistry.
Solvation – It is the process of swelling, gelling, or dissolving a resin by a solvent or plasticizer. It is a stabilizing interaction of a solute with a solvent, or a similar interaction between a solvent and groups of an insoluble material (e.g., the ionic groups of an ion-exchange resin). Such interactions normally involve electrostatic forces and van der Waals forces, as well as compound-specific effects such as hydrogen bonding.
Solvation effects – These refer to the influence of solvents on the reactivity of solutes, stemming from both general properties such as polarity and polarizability, as well as specific interactions like hydrogen-bonding and donor ability. These effects are crucial for analyzing solute–solvent interactions, although their complexity poses challenges in quantification.
Solvency – It is the property of removal of soils by dissolving in a cleaning solution. For example, oils and fats are soluble in some solvents.
Solvent – It is a normally liquid substance capable of dissolving or dispersing other substances. It is the component of either a liquid or solid solution which is present to a larger or major extent. It is the component which dissolves the solute.
Solvent casting technique – It is a method where a polymer is dissolved in a suitable solvent, which is then placed in a mould along with particles, and upon solvent evaporation, creates a composite material with a porous structure.
Solvent cleaning – It is cleaning by means of organic solvents. It is the initial surface preparation method which removes contaminants such as release agents and machine oils from parts before and after abrasive treatments, utilizing different solvents to ensure effective cleaning.
Solvent cold cleaning and vapour degreasing – Solvent cleaning is a surface preparation process that is especially adept at removing organic compounds such as grease or oil from the surface of a metal. Majority of the organic compounds are easily solubilized by organic solvent and removed from the work-pieces. In some cases, solvent cleaning before other surface preparations can extend the life of cleaning operations and reduce costs. In other cases, solvent cleaning prepares work-pieces for the next operation, such as assembly, painting, inspection, further machining, or packaging. Before plating, solvent cleaning is normally followed by an alkaline wash or another similar process which provides a hydrophilic surface. Solvent cleaning can also be used to remove water from electro-plated parts, a common procedure in the jewelry industry. Solvent cleaning can be accomplished in room-temperature baths or by using vapour degreasing techniques. Room temperature solvent cleaning is referred to as cold cleaning. Vapour degreasing is the process of cleaning parts by condensing solvent vapours of a solvent on work-pieces. Parts can also be degreased by immersion in the hot solvent, as well as by exposure to the solvent vapour. Drying is accomplished by evaporating the solvent from the parts as they are withdrawn from the hot solvent vapour. In cold cleaning, parts are dried at room temperature or by the use of external heat, centrifuging, air blowing, or an absorptive medium. The use of several industrial solvents is being severely restricted because of health, safety, and environmental concerns.
Solvent evaporation – It is the process where liquid molecules escape the surface of a solution and become a gas (vapour), thereby removing the solvent and concentrating or solidifying the remaining solute in a mixture. This process can occur naturally, like puddles drying on a warm day, but is also used in laboratories and industries to isolate compounds, create powders, and prepare samples for analysis. Techniques to control and accelerate solvent evaporation include increasing temperature, reducing pressure (using vacuum), and introducing mixing.
Solvent extraction dewatering process – The solvent extraction dewatering process is based on the principle of variation of water solubility in nonpolar solvent. The common solvents used are dimethyl ether (DME), supercritical carbon di-oxide, toluene, and anisole etc. The process reduces the tendency of spontaneous ignition. For some solvents like dimethyl ether, technological requirements and energy consumption are low. The organic solvent increases the moisture extraction cost. The drying rate of the lignite coal by this method is low. The process is difficult to realize for large scale installation.
Solvent extraction-electro-winning (SX-EW) – It is a metallurgical technique, so far applied only to copper ores, in which metal is dissolved from the rock by organic solvents and recovered from solution by electrolysis.
Solvent extraction technology – The solvent extraction route technology is a popular regeneration technology. This regeneration technology is preferred since it produces less hazardous by-products in the process of treating spent pickling liquor. By using the solvent extraction technology, ferrous chloride can be separated from hydrochloric acid. The by-product produced from the regeneration of hydrochloric spent pickling liquor is required to go through post-treatment.
Solvent medium – It is the main substance, like water or alcohol, which dissolves a solute to form a solution, acting as the surrounding environment for the dissolved component. It is the liquid (or gas, or solid) in which the solute disperses, allowing for chemical reactions or cleaning processes to occur by dissolving contaminants or other substances.
Solvent molecules – These are those which make up the substance capable of dissolving another substance, known as the solute, to form a homogeneous mixture called a solution. Solvents are typically present in the largest quantity in a solution and can be in liquid, solid, or gaseous states. Common examples include water, a polar solvent, and hexane, a non-polar solvent.
Solvent precipitation – It is a method for producing polymer powders through techniques such as spray drying or phase separation, which results in relatively spherical particles with controlled diameters by selecting appropriate polymer-solvent pairings. This method is specific to certain polymer families and generates significant solvent waste.
Solvent recovery column – The solvent recovery column is used for separation of the non-aromatics present at the top of the extractive distillation column from the residual solvent. A portion of the bottom is fed to the solvent separator in order to recover N-Formylmorpholine (NFM). The solvent separator splits the liquid into two liquid phases. The non-aromatic-rich phase is returned to the ‘solvent recovery column’, while the N-Formylmorpholine rich phase is directed to the ‘extractive distillation column’ (lean solvent circuit). The solvent recovery column in combination with the solvent separator reduces the use of N-Formylmorpholine. This section is controlled by pressure, temperature and level controllers. N-Formylmorpholine recovered at the bottom of the column is returned to the extractive distillation column. The solvent recovery column minimizes the N-Formylmorpholine losses by means of extensive recalculation of N-Formylmorpholine flow inevitably leaving the top of the extraction column.
Solving tool – It refers to a method or set of rules used in problem-solving which aids in identifying features of a problem and deriving general rules from problem-solution pairs. This includes different forms of analytical learning, such as explanation-based learning, macro-operators, and heuristics.
Solvus – In a phase or equilibrium diagram, it is the locus of points representing the temperature at which solid phases with different compositions coexist with other solid phases, i.e, the limits of solid solubility.
Sommerfeld number – It is a dimensionless number which is used to evaluate the performance of journal bearings. It is numerically defined as (P/nU).(c/r)square, where ’P’ is the load per unit width, ‘n’ is the dynamic viscosity, ‘U’ is the surface velocity, ‘c’ is the radial clearance, and ‘r’ is the bearing radius. At lower concentricities, it is convenient to use the Sommerfeld number in the form given. Since it tends to infinity as the eccentricity approaches unity, the reciprocal form is frequently used in the case of heavily loaded bearings. The expression (nN/p).(r/c)square in which ‘N’ is the frequency of rotation and ‘p’ is the pressure, is sometimes referred to as the Sommerfeld number.
Sonar signal processing – It refers to the methods used to prepare and analyze sonar analog signals, which typically involves front-end components like beamformers, filters, and amplifiers, and often includes the translation of narrowband signals to baseband for practical digital processing.
Sonication – It is the act of applying sound energy to agitate particles in a sample, for different purposes such as the extraction of multiple compounds from plant, micro-algae and seaweeds. Ultrasonic frequencies (higher than 20 kilo-hertz) are normally used, leading to the process also being known as ultra-sonication.
Sonic conditions – These refer to the state when the fluid flow velocity in a choke reaches the speed of sound under localized temperature and pressure, resulting in a pressure discontinuity which prevents downstream pressure changes from affecting upstream pressure.
Sonic flow – It is defined as the condition in which the fluid flow velocity in a choke reaches the traveling velocity of sound in the fluid, resulting in a pressure discontinuity where downstream pressure changes do not affect upstream pressure. This occurs when the downstream to upstream pressure ratio is less than a critical pressure ratio.
Sonic-meter for slopping detection – Since the beginning of the 1970s, a device called sonic-meter has been employed in several converter shops for indirect monitoring of slag foam level. The basic idea is that as the foam level increases, the sound emission from the converter under blowing decreases at certain frequency bands. The sonic-meter signal is usually used by the operator for monitoring slag level changes but it has also been employed as a controller input.
Sonic method – It is defined as a technique which utilizes hammer blows to create sonic impulses, with the travel time of these pulses measured to assess material properties, such as modulus of elasticity and strength. This method can also involve tools like chain drags and sounding rods for detecting delamination in horizontal surfaces.
Sonic testing – It is normally known as ultrasonic testing (UT). It is a non-destructive testing method which uses high-frequency sound waves (ultrasound) to evaluate the internal and external integrity of materials, typically by detecting internal flaws, measuring thickness, and determining the condition of welds and other components. The process involves sending these sound waves into the material and analyzing the reflected waves (echoes) to identify changes in density, such as cracks, voids, or delaminations, and to measure the material’s thickness. Sonic testing uses sound waves above audible frequency through a supersonic reflectoscope to measure time sound waves take returning from opposite sides of casting. Defects return the waves in more or less time.
Sonic velocity – It is the speed of sound. It is the maximum speed at which a wave or pressure disturbance can travel through a compressible fluid. It is a key concept in fluid dynamics, frequently used to determine if flow has reached a ‘choked condition’ where mass flow rate no longer increases. The Mach number, the ratio of a fluid’s flow velocity to its sonic velocity, indicates its speed relative to sound namely Mach 1 is sonic, less than 1 is sub-sonic, and higher than 1 is super-sonic.
Sonograph – It is the squared magnitude of the output from a bandpass filter, representing the time-frequency characteristics of a signal by analyzing its spectrum through filter banks. It is characterized by a non-linear process which does not introduce artifacts, similar to the spectrogram.
Soot – It is unburned particles of carbon derived from hydrocarbons. It is a black, carbon-rich particulate matter produced by incomplete combustion. It is a major by-product of burning fuels like coal, wood, and oil, and can be found in exhaust, chimneys, and even on surfaces after a fire. In the context of exhaust, soot appears as black smoke, indicating a high concentration of particulate matter.
Soot blower – It is a system which cleans soot deposits from the internal surfaces of boilers by using a high-pressure blast of steam or air to dislodge them. This periodic cleaning action helps to maintain the boiler’s heat transfer efficiency, improve performance, reduce emissions, and extend its operational life. It is a mechanical device for discharging steam or air to clean heat absorbing surfaces.
Soot particles – These are particles formed during the quenching of gases at the outer edge of flames of organic vapours consisting predominantly of carbon, with lesser quantities of oxygen and hydrogen present as carboxyl and phenolic groups and showing an imperfect graphitic structure.
Sorbite – It is an obsolete term. It is a fine mixture of ferrite and cementite produced either by regulating the rate of cooling of steel or by tempering steel after hardening. The first type is very fine pearlite which is difficult to resolve under the microscope, while the second type is tempered martensite.
Sorel cement – It is also known as magnesia cement or magnesium oxy-chloride. It is a non-hydraulic cement. It is a mixture of magnesium oxide (burnt magnesia) with magnesium chloride having the approximate chemical formula Mg4Cl2(OH)6(H2O)8, or MgCl2·3Mg(OH)2·8H2O, corresponding to a weight ratio of 2.5–3.5 parts MgO to one-part MgCl2. The set cement consists mainly of a mixture of magnesium oxy-chlorides and magnesium hydroxide in varying proportions, depending on the initial cement formulation, setting time, and other variables. The main stable oxy-chlorides at ambient temperature are the so-called ‘phase 3’ and ‘phase 5’, whose formulas can be written as 3Mg(OH)2·MgCl2·8H2O and 5Mg(OH)2·MgCl2·8H2O, respectively, or, equivalently, Mg2(OH)3Cl.4H2O and Mg3(OH)5Cl·4H2O. Phase 5 crystallizes mainly as long needles which are actually rolled-up sheets. These interlocking needles give the cement its strength. In the long term the oxy-chlorides absorb and react with carbon di-oxide (CO2) from the air to form magnesium chloro-carbonates.
Soret coefficient – It is the ratio of the thermal diffusion coefficient divided by the ordinary diffusion coefficient.
Soret effect – It is where small light molecules and large heavy molecules separate under a temperature gradient. Normally, this effect is important where more than one chemical species is present under a very large temperature gradient such as chemical reactors. This effect is found when solving the species mass fraction equations.
Sorption – It is defined as the process by which a substance (sorbate) is sorbed (adsorbed or absorbed) on or in another substance (sorbent).
Sorption properties – These refer to the characteristics of sorption materials which influence their ability to store energy, including factors such as pore structure, sorption capacity, sorption / desorption rate, sorption heat, and thermal conductivity. These properties are critical in evaluating the performance of sorption energy storage systems.
Sorptivity – It is a technique used to measure the amount of water absorbed by capillary action, typically expressed in terms of the coefficient of sorptivity. It can indicate characteristics such as durability in concrete mixes, particularly when modified with materials like e-waste, which show lower sorptivity because of their water-phobic properties.
Sortation conveyor – It is a cutting-edge conveyor which is engineered to categorize and organize products based on predetermined destinations. This sorting mechanism improves logistics efficiency, reducing manual sorting requirements. Regular assessments are crucial to maintain the precision and effectiveness of sortation conveyors, ensuring accurate product segregation.
Sorting – Sorting is the process of separating the different metals and other materials from steel scrap. This is done using magnets, eddy current separators, screening, blowing / suction (air classifier), flotation (gravitational separation), optical separation, and manual separation. Manual sorting involves obviously the removal of components from the scrap by hand. By this method the separation of steel scrap from non-metallics is accomplished manually.
Sound – It is defined as ‘(i) oscillation in pressure, stress, particle displacement, particle velocity, etc., propagated in a medium with internal forces (e.g., elastic or viscous), or the superposition of such propagated oscillation, and (ii) auditory sensation evoked by the oscillation described in (i)’. Sound is a vibration which propagates as an acoustic wave through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the reception of such waves and their perception by the brain. Only acoustic waves which have frequencies lying between about 20 hertz and 20 kilohertz, the audio frequency range, elicit an auditory percept in humans. In air at atmospheric pressure, these represent sound waves with wavelengths of 17 meters to 1.7 centimeters. Sound waves above 20 kilohertz are known as ultrasound and are not audible to humans. Sound waves below 20 hertz are known as infrasound.
Sound absorption coefficient – It is the ratio of absorbed sound energy to incident sound energy, reflecting a material’s ability to absorb sound, and it varies with sound frequency and direction of incidence.
Sound absorption properties – These refer to the measure of energy removal from sound waves as they pass through a material, with effective materials converting sound into heat and showing characteristics which improve soundproofing capabilities. Typically, materials like foamed plastics and elastomers demonstrate superior sound absorption compared to semicrystalline or crystalline materials.
Sound barrier – It is also called sonic barrier. It is the large increase in aerodynamic drag and other undesirable effects experienced by an object when it approaches the speed of sound.
Sound frequency – It is the number of cycles per second at which sound is generated, measured in hertz (Hz). It determines the pitch of the sound, with higher frequencies producing a shriller tone.
Sound insulation – It is a measure to prevent sound waves from permeating, demonstrated by sound transmission loss measured in decibels. It involves the use of dense and heavy materials to reduce the vibration and transmission of both air-borne and solid-borne sounds.
Sound intensity – It is the average rate at which sound energy is transmitted through a unit area perpendicular to the direction of propagation at a specific point, measured in watts per square meter.
Sound level meter (SLM) – It is a device which measures sound pressure levels, mainly displaying readings in decibels (dB), and typically comprises a microphone, amplifier, weighting networks, rectifier, and calibrated meter. Sound level meters can measure both the root mean square (rms) value and peak levels of sound, with different grades specified for different measurement applications.
Soundness – It is the ability of a material, like cement or aggregate, to resist destructive volume changes after hardening or exposure to weathering, such as freezing-thawing or wetting-drying. A sound material maintains its shape and volume without cracking or deteriorating, ensuring durability and strength in the final structure. For example, a sound cement paste doesn’t expand or contract after setting, while a sound aggregate resists breakdown when exposed to environmental conditions.
Sound propagation – It refers to the transmission of sound waves through a medium, such as sea water, and is influenced by the physical and chemical properties of that medium.
Sound recording – It is the technology of recording sound for later reproduction.
Sound signal – It is a waveform of pressure oscillations characterized by its duration, amplitude, envelope, and frequency content. It can be represented as a sum of sine waves through Fourier analysis, and is frequently analyzed using spectrograms to capture its complex variations.
Sound transmission – It is the process by which sound energy propagates through different regions, which can be inhibited by methods such as absorption into materials or reflection through changes in acoustic impedance.
Sound velocity – It is the speed at which sound waves travel through a medium, determined by the medium’s density and compressibility, with denser materials transmitting sound faster.
Source – It normally refers to a component or element which provides or delivers a specific type of energy or signal to a system or circuit. This can be an electrical source, a mechanical source, a thermal source, or several others. Essentially, a source is the origin or starting point of the energy or signal being used. Source is also a process, activity, or mechanism which releases a green-house gas, an aerosol or a precursor of a green-house gas or aerosol into the atmosphere.
Source control drawing – It provides engineering description and acceptance criteria for purchased items which need design-activity imposed qualification testing and exclusively provide performance, installation, and interchangeability characteristics specifically required for the critical applications. It establishes item identification for the controlled items. It is used to provide a means of establishing engineering requirements for the selection, qualification testing, and acquisition of an item, and documentation to assure interchangeability of specified items. It includes (i) configuration, (ii) dimensions of item envelope and their limits, (iii) mounting and mating dimensions and their limits, (iv) interface characteristics and their limits, (v) acceptance criteria, (vi) qualification test requirements, (vii) performance, maintainability, reliability, environmental, and other functional characteristics, (viii) schematic, interconnection, or other appropriate diagram to define item function or provide interconnection information, and (ix) identification requirements including marking instructions.
Source-detector distance – It is also known as source-image distance (SID) or source-detector separation (SDS), It refers to the physical distance between the radiation source (like an X-ray tube) and the detector (like the image receptor). This distance is a crucial parameter in several applications, including imaging, scientific research, and industrial inspection.
Source reduction – It is also known as waste prevention. It is the practice of reducing or eliminating the creation of waste, pollutants, or contaminants at their source before they enter the waste stream or are released into the environment.
Sources – Sources, such as bioenergy, geothermal, hydro-marine, solar, wind, injection for storage, hydrocarbons, minerals, nuclear fuels and water, are the feedstock for resource projects from which products can be developed. The sources can be in their natural or secondary (anthropogenic sources, tailings, etc.) state.
Source-to-object distance (SOD) – It refers to the distance between the focal spot of the X-ray tube and the object being imaged. It is a crucial factor in determining image quality, affecting magnification and distortion. Understanding of source-to-object distance is necessary for optimizing image acquisition in different imaging modalities such as radiography, and fluoroscopy.
Source (X-rays) – It is the area emitting primary X-rays in a diffraction experiment. The actual source is always the focal spot of the X-ray tube, but the virtual source can be a slit or pinhole, depending on the conditions of the experiment.
Sourcing process – It includes every activity which revolves around identifying and assessing potential suppliers as well as selecting and engaging with an appropriate supplier who offers the best value. At the end of the sourcing process, normally a contract is signed or an agreement is reached between the buyer and the supplier on what is to be procured and the terms of contract.
Source-to-object distance (SOD) -it is also known as focus-to-object distance (FOD). It is the distance between the X-ray source (focal spot) and the object being imaged. It is a key factor in radiographic imaging, affecting image quality and magnification.
Sour crude oil – It is crude oil with a high sulphur content, which needs more severe processing to remove the sulphur and is normally considered less valuable because of the undesirable characteristics of sulphur in petroleum products.
Sour gas – It is a gaseous environment containing hydrogen sulphide and carbon di-oxide in hydro-carbon reservoirs. Prolonged exposure to sour gas can lead to hydrogen damage, sulphide-stress cracking, and / or stress-corrosion cracking in ferrous alloys.
Sour water – It means waste waters containing fetid materials, normally sulphur compounds.
Sow block – It is a block of heat-treated steel placed between the anvil of the hammer and the forging die to prevent undue wear to the anvil. Sow blocks are occasionally used to hold insert dies. It is also called anvil cap.
Space-charge aberration – It is an aberration resulting from the mutual repulsion of the electrons in a beam. This aberration is most noticeable in low-voltage, high-current beams. This repulsion acts as a negative lens, causing rays, which were originally parallel, to diverge.
Space constraints – It mean limitations on the available physical or digital space. These constraints can affect how objects or information are arranged, stored, or utilized. In essence, it is a situation where the available space is smaller than what is ideally needed.
Space frame – It is also called or space structure (3D truss). It is a rigid, lightweight, truss-like structure constructed from interlocking struts in a geometric pattern. Space frames can be used to span large areas with few interior supports. Like the truss, a space frame is strong because of the inherent rigidity of the triangle, flexing loads (bending moments) are transmitted as tension and compression loads along the length of each strut.
Space lattice – It is a regular, periodic array of points (lattice points) in space which represents the locations of atoms of the same kind in a perfect crystal. The concept can be extended, where appropriate, to crystalline compounds and other substances, in which case the lattice points frequently represent locations of groups of atoms of identical composition, arrangement, and orientation.
Spacer – It is a component which creates or maintains a desired distance between two or more parts in an assembly. They can be simple, unthreaded tubes or more complex components with threads or other features. Spacers are important for ensuring proper fit, function, and performance in different applications, from electronics to construction.
Spacer strip – It is a metal strip or bar prepared for a groove weld and inserted in the joint root to serve as a backing and to maintain the root opening during welding. It can also bridge an exceptionally wide root opening because of the poor fit.
Space structures – These structures need high stiffness, low coefficient of thermal expansion, and dimensional stability during the operational lifetime. High-performance composites do satisfy these requirements, and also offer the minimum weight material solution for space applications.
Space truss – It is a structural framework comprised of interconnected rods at nodes, which are spherical hinges which permit relative rotation, allowing the structure to deform without bending. The elastic energy of a space truss element arises solely from axial deformation.
Space vector modulation – It is a control strategy for variable frequency motor drives.
Spacing (lattice planes) – It is the perpendicular distance between adjacent parallel lattice planes.
Spade drill – The preferred term flat drill. It is a rotary end-cutting tool constructed from a flat piece of material, provided with suitable cutting lips at the cutting end.
Spallation – It is the cracking or rupturing of a solid body, which normally results in the detachment of a portion of the solid.
Spalled concrete – It is the breaking-off of layers from the concrete surface because of the applied heat during a fire, which can occur either locally or widely depending on factors such as moisture content and the properties of the aggregate. This phenomenon includes both explosive spalling, which happens early in fire exposure, and sloughing, a later process where areas of concrete cover fall away.
Spalling – It is the separation of particles from a surface in the form of flakes. The term spalling is normally associated with rolling-element bearings and with gear teeth. Spalling is normally a result of sub-surface fatigue and is more extensive than pitting. It is also the spontaneous chipping, fragmentation, or separation of a surface or surface coating. It is a chipping or flaking of a surface because of a kind of improper heat treatment or material dissociation. In refractories, spalling means fracture or rupture of a refractory resulting in the physical detachment of pieces of the refractory. It is the breaking off of the surface of refractory material as a result of internal stresses. In case of concrete, spalling is the complete failure of concrete because of the expansive forces caused by the formation of corrosion products on unprotected reinforcement bars.
Spalling of refractories, mechanical – It is the spalling of a refractory unit caused by stresses resulting from impact or pressure.
Spalling of refractories, structural – It is the spalling of a refractory unit caused by stresses resulting from differential changes in the structure of the unit.
Spalling of refractories, thermal – It is the spalling of a refractory unit caused by stresses resulting from nonuniform changes of the unit produced by a difference in temperature.
Spalling, roll failure – Spalling can be another reason for roll failure. There are two different kinds of spalls in the rolls. One starts at an initial surface crack while the other kind starts at the sub-surface. Surface cracks are normally caused by local overload, and all types of rolling abnormalities including abnormal rolling conditions. There are five types of spalls. These are (i) saddle spalls, (ii) pressure cracks and ribbon fatigue spalls, (iii) shell / core interface-bond related spalls, (iv) spalls due to insufficient shell depth, and (v) barrel edge spalls.
Span – It is the distance between two adjacent structural supports (e.g., two piers) of a structural member (e.g., a beam). Span is measured in the horizontal direction either between the faces of the supports (clear span) or between the centres of the bearing surfaces (effective span). A span can be closed by a solid beam or by a rope. Span is a significant factor in finding the strength and size of a beam as it determines the maximum bending moment and deflection.
Span deflection – It describes the quantity a structural element, such as a beam or tunnel wall, bends or deforms downwards under load, relative to its original span or length. It is a critical measure of structural performance, indicating how much a structure deviates from its straight line under applied forces. Engineers use span deflection to assess a structure’s integrity, verify its elastic performance, and ensure it meets specific deflection limits for its intended use.
Spangle – It is the characteristic crystalline form in which a hot dipped zinc coating solidifies on steel strip. This characteristic crystalline form is shown by the solidified, hot dipped zinc coating. Crystalline formations on the surface of the galvanized coating are caused by the presence of lead and other alloying elements in the galvanizing bath.
Spangle free zinc coated steels – These steels are having a uniform finish in which the surface irregularities created by spangle formation are not visible to the naked eye. The finish is produced by a combination of coating bath chemistry, or cooling or both.
Spare parts – These are interchangeable components kept in inventory to repair or replace defective parts. They are designed to be easily replaced or fitted, and are essential for maintaining the functionality of machinery and other devices.
Spare parts inventory – It refers to the collection of replacement components held in stock to repair or maintain machinery, equipment, or other products. This inventory is important for minimizing downtime and ensuring operational efficiency, especially in industries where equipment reliability is paramount. Basically, it is a dedicated stock of items kept on hand to fix equipments when they break down.
Spare parts management – It plays an important role in achieving the desired plant availability at an optimum cost. It is the process of managing the inventory of spare components needed for equipment maintenance and repair. It brings together the diverse disciplines of maintenance management, inventory management, storeroom management, supply chain, procurement and logistics. This adds a layer of complexity which is normally not found with other inventory types.
Spare parts optimization – It is the strategic management of spare parts inventory through the computerized maintenance management system (CMMS) to ensure that critical components are available when needed. Spare parts optimization involves balancing stock levels, reducing excess inventory, and minimizing costs while maintaining operational readiness.
Spark – It is a tiny bright piece of burning material which flies up from something that is burning. Sparks flew off in all directions. In case of electricity, spark is a sudden, brief discharge of electricity which occurs when an electric field overcomes the resistance of a material, frequently air or other insulators, creating a visible flash of light. This can happen when two conductors are separated by a gas or when a high voltage is applied across a gap.
Spark atomic emission spectrometry – It is a method of chemical analysis which uses the intensity of light emitted from a spark at a particular wavelength to determine the quantity of an element in a sample. The wavelength of the atomic spectral line gives the identity of the element while the intensity of the emitted light is proportional to the number of atoms of the element. Spark atomic emission spectroscopy is used for the analysis of metallic elements in solid samples. For non-conductive materials, the sample is ground with graphite powder to make it conductive. In traditional arc spectroscopy methods, a sample of the solid is normally ground up and destroyed during analysis. An electric arc or spark is passed through the sample, heating it to a high temperature to excite the atoms within it. The excited atoms emit light at characteristic wave-lengths which can be dispersed with a monochromator and detected. The spark source with controlled discharge is for quantitative analysis. Both qualitative and quantitative spark analyses by spark atomic emission spectrometry are widely used for the purpose of quality control.
Spark coil leak detector – It is a high frequency discharge coil of the Tesla type which indicates pin holes in glass vacuum systems by a spark jumping between the core of the coil and the pin hole.
Spark cutting – It refers to a process which utilizes electric sparks to cut materials, particularly effective for metal foams made by powder metallurgy. This method allows for adjustable material size and controlled surface quality, with pulse width being a critical factor influencing surface roughness.
Spark erosion – It is also called electrical pitting. It is the formation of surface cavities by removal of metal as a result of an electrical discharge across an interface.
Spark erosion machining (SEM) – It is a thermal type advanced machining process which removes work-piece material through controlled erosion caused by melting and vapourization from a series of electric sparks occurring between an electrically conducting work-piece and a complementary-shaped tool, in the presence of a suitable dielectric fluid.
Spark-gap transmitter – It is a former type of radio transmitter which generated radio frequency current by exciting resonance of a tuned system with an electric spark. It is used almost entirely for transmission of Morse code.
Spark ignition – It refers to the process of starting the combustion of a fuel-air mixture in an engine using an electric spark. This method is normally used in gasoline engines, where a spark plug initiates the burning of the compressed air-fuel mixture.
Spark-ignition engine (SI engine) – It is an internal combustion engine, normally a petrol engine, where the combustion process of the air-fuel mixture is ignited by a spark from a spark plug. This is in contrast to compression-ignition engines, typically diesel engines, where the heat generated from compression together with the injection of fuel is enough to initiate the combustion process, without needing any external spark. Spark-ignition engines can (and increasingly are) run on fuels other than petrol / gasoline, such as auto-gas (LPG), methanol, ethanol, bio-ethanol, compressed natural gas (CNG), hydrogen, and (in drag racing) nitro-methane.
Spark leak test – It is also known as a spark test or holiday detection. It is a high-voltage non-destructive method which is used to find pinholes, cracks, or discontinuities in coatings, linings, or insulations. It detects defects by applying a high voltage across the material. When the probe encounters a fault, a spark is discharged, indicating a leak.
Spark optical emission spectrometry – It is also known as spark optical emission spectrography. It is a chemical analysis technique which is used to identify the elemental composition of metallic materials. It involves creating a spark on the sample’s surface, which excites atoms and ions, causing them to emit light at specific wave-lengths. These emitted wave-lengths are then analyzed to determine the elements present and their concentrations. Spark optical emission spectrometry is frequently used in metallurgical industry, geological field and for monitoring of the environment.
Spark plasma sintering (SPS) – It is a rapid sintering technique which uses pulsed direct current and pressure to consolidate powdered materials into solid parts. It is an advanced powder metallurgy process which combines heat and pressure for rapid densification, offering advantages like shorter processing times and improved material properties.
Spark plug – It is a critical component in igniters which creates an electrical spark to ignite a gas mixture in a small chamber. It is necessary to select the appropriate spark plug to avoid issues such as sooting or overheating, which can impede ignition.
Spark sintering – It is a pressure sintering or hot-pressing method which provides for the surface activation of the powder particles by electric discharges generated by a high alternating current applied during the early stage of the consolidation process.
Spark source mass spectrometry (SSMS) – It is a technique which is used for the qualitative and quantitative analysis of elements in various samples, particularly solid samples. It involves ionizing a sample with a high-voltage radio frequency spark and then analyzing the resulting ions based on their mass-to-charge ratio using a mass spectrometer.
Spark spread – It is the difference between the revenue from selling a unit of electricity and the cost of the fuel used to make it.
Spark testing – It is a method which is used for the classification of ferrous alloys as per their chemical compositions, by visual examination of the spark pattern or stream which is thrown off when the alloys are held against a grinding wheel rotating at high speed. Spark testing of steel is a useful method for identifying the type of steel. It has capabilities of determining the relative carbon content of the steels. Spark test is a simple identification test which is used to observe the colour, spacing, quantity, and quality of sparks produced by grinding of steel sample. When held lightly against a grinding wheel, the different kinds of iron and steel produce sparks which vary in length, shape, and colour. These sparks can be compared to a chart or to sparks from a known test sample to determine the classification. Spark testing is normally used to sort ferrous materials, establishing the difference from one another by noting whether the spark is the same or different. Cast iron also provides a characteristic type of spark.
Sparse Bayesian learning (SBL) – It is a statistical method which uses different variances for the priors of unknown parameters, treating these variances as deterministic parameters to get estimates and compute predictive distributions. It generalizes prior models by integrating out parameters using Type II maximum likelihood methods.
Sparse signal representation (SSR) – It is the representation of a signal using a minimal number of non-zero coefficients from a dictionary, aiming to capture the essential features of the signal while separating true components from noise. It is formulated as an optimization problem to achieve a concise and effective analysis of complex signals.
Spatial averaging – It is a process which relates the average of a gradient of a quantity to the macroscopic gradient of its average, particularly in the context of layered porous media, incorporating boundary and interface terms.
Spatial characteristics – These refer to the physical attributes of a control interface, including its size, shape, weight, the number and size of targets, and the spacing between those targets. These characteristics are to align with an individual’s motor skills to facilitate effective interaction.
Spatial coordinates – These refer to the coordinate system of the space containing an object to be measured, which can be n-dimensional, with ‘n’ being 3 for volume data, 2 for slices, and 1 for specific examples.
Spatial grain size – It is the average size of the three-dimensional grains, as opposed to the more conventional grain size determined by a simple average of observations made on a cross section of the material.
Spatial scale – It is a specific application of the term scale for describing or categorizing (e.g., into orders of magnitude) the size of a space (hence spatial), or the extent of it at which a phenomenon or process occurs, e.g., in physics an object or phenomenon can be called microscopic if too small to be visible. In climatology, a micro-climate is a climate which can occur in a mountain, valley or near a lake shore. In statistics, a mega-trend is a political, social, economical, environmental, or technological trend which involves the whole planet or is supposed to last a very large quantity of time. The concept is also used in geography, astronomy, and meteorology. These divisions are somewhat arbitrary, where, as shown in Table 2, mega- is assigned global scope, it can only apply continentally or even regionally in other contexts. The interpretations of meso- and macro- is then to be adjusted accordingly.
| Table 2 Examples of scales in geography and meteorology | |||
| Scale | Length | Area | Description |
| Micro | 1 m – 1 km | 1 m2 – 1 km2 | Local |
| Meso | 1 km – 100 km | 1 km2 – 10,000 km2 | Regional |
| Macro | 100 km – 10,000 km | 10,000 km2 – 100,000,000 km2 | Continental |
| Mega | 10,000 km – 1,000,000 km | 100,000,000 – 10,000,000,000 km2 | Global |
| Giga | Higher than 1,000,000 km | Higher than 10,000,000,000 km2 | Super-global |
| Note: m – meter, km – kilometers, km2 – square kilometers | |||
Spatial structure – It is an engineering solution which achieves minimal stiffness and strength necessary for safety, frequently utilizing steel or steel composite materials in innovative ways rather than traditional methods. Examples include different types of bridges, such as stress ribbon bridges.
Spatial variation – It is the difference or change in a phenomenon, data, or characteristic across different geographical locations. It describes how things vary from one place to another, such as differences in rainfall, soil quality, disease prevalence, or population density across an area. This concept is distinct from temporal variation, which refers to changes over time at a single location.
Spatter – It is the metal particles expelled during arc or gas welding. These particles do not form part of the weld.
Spatter loss – It is the metal lost due to spatter.
Spearman’s rank order correlation – It is a non-parametric test used to measure the relationship between two rank ordered scales. Data are in ordinal form.
Special alloy steels – These steels are designed for extreme service requirements. They include steels with very high heat resistance, corrosion resistance, or wear resistance etc.
Special bar quality (SBQ) – It represents a wide variety of higher quality carbon and alloy steel bars which are used in the forging, machining, and cold-drawing industries for the production of automotive parts, hand tools, electric motor shafts, and valves. It normally contains more alloys than merchant quality and commodity grades of steel bars, and is produced with more precise dimensions and chemistry.
Special bar quality rolling mills – These rolling mills are used for rolling special bar quality steel grade products. Special bar quality mill products include rounds, flats, squares, hexagons, and tubes.
Special bar quality (SBQ) steel – It is the steel which is used for a class of long products engineered for very tough application. The higher the load of application, the more special is the special bar quality steel. The term ‘special bar quality’ is a term predominantly being used in North American steel industry. In Europe, special bar quality steels are normally known as engineering steels. Both of these terms refer to steel types as well as to bar products, and as they are frequently with associated with the steel grades and they refer to billet and slab as well as bar. The ‘special bar quality’ steel term is used to describe steel long products having properties for more demanding processing or end-use applications which cannot be met by merchant bar quality (MBQ) steel grades. Special bar quality steels represent a wide variety of higher quality plain carbon and alloy steel
Special cast irons – These are alloy cast irons which take advantage of the radical changes in structure produced by rather large quantities of alloying elements. Abrasion resistance can be improved by increasing hardness, which in turn can be achieved by either increasing the quantities of carbides and their hardness or by producing a martensitic structure. The least expensive material is white iron with a pearlitic matrix. Additions of 3 % to 5 % nickel and 1.5 % to 2.5 % chromium result in cast irons with (FeCr)3C carbides and an as-cast martensitic matrix. Additions of 11 % to 35 % chromium produce (CrFe)7C3 carbides, which are harder than the iron carbides. Additions of 4 % to 16 % manganese result in a structure consisting of (FeMn)3C, martensite, and work-hardenable austenite. Heat resistance depends on the stability of the microstructure. Cast irons used for these applications can have a ferritic structure with graphite (5 % silicon), a ferritic structure with stable carbides (11 % to 28 % chromium), or a stable austenitic structure with either spheroidal or flake graphite (18 % nickel, 5 % silicon). For corrosion resistance, irons with high chromium (up to 28 %), nickel (up to 18 %), and silicon (up to 15 %) are used.
Special cause – It refers to a specific, identifiable factor which causes a variation or deviation in a process or system’s output that is not part of the normal, predictable variation of the process. These variations are unusual, frequently unexpected, and can be attributed to a specific, identifiable event or factor. It is a cause which results in unusual variation in the output of a process. It is also called an assignable cause.
Specialist contractor – It is a highly skilled organization or individual in the construction industry who focuses on a specific area of work. Unlike a normal contractor who oversees an entire project, specialist contractors provide technical expertise and perform specialized tasks which go beyond the scope of normal work, frequently working on complex projects that require deep knowledge of their specific field.
Specialized construction – It refers to construction practices which leverage specific knowledge management processes to improve performance and collaboration among stakeholders, improving decision-making and adaptability throughout all phases of a project. This approach supports sustainable construction by facilitating the transfer and reuse of knowledge, ultimately addressing industry challenges.
Specialized operations – It refer to customized procedures and equipment used to ensure constant well control, including techniques such as wireline, coiled tubing, snubbing, and managed pressure operations. These operations need precise installation, testing, and maintenance of equipment to create multiple barriers for the protection of personnel and the environment.
Specialized rolling mills – These mills produce specialized products by combining rolling process with other processes. Under this classification the major types of mills are skew rolling mill, transverse tolling mill, ring rolling mill, and thread rolling mill.
Specialized structures – These are unique constructions designed for specific applications, such as moveable scaffold structures used in large bridge projects, which need particular design considerations and compliance with relevant codes.
Special property – It is the property which is not determined as part of the routine inspection and test requirements. (e.g., fatigue properties).
Special purpose materials – These materials are designed and used for specific applications which need unique properties or performance characteristics not found in general-purpose materials. These materials are frequently engineered to withstand harsh conditions, show specific behaviours, or offer unique functionalities like high resistance, corrosion resistance, or bio-compatibility.
Special-purpose parts – These are parts which are designed and manufactured especially for use in a particular product.
Special steels – These are the steels where during the production special care is to be taken so as to attain the desired cleanliness, surface quality and mechanical properties.
Special structure mills – They have skew axes of rolls and are used for the production of seamless tubes.
Special surface – It entails a product with minimal frequency and severity of seams and other surface defects.
Special theory of relativity – It is a scientific theory of the relationship between space and time. The theory is based on just two postulates. The first postulate is that the laws of physics are invariant (identical) in all inertial frames of reference (i.e., frames of reference with no acceleration). This is known as the principle of relativity. The second postulate is that the speed of light in vacuum is the same for all observers, regardless of the motion of light source or observer. This is known as the principle of light constancy, or the principle of light speed invariance.
Specialty mills – These mills are used for the rolling of wheel, tyre, thread, and grinding balls etc.
Specialty steel – It is the category of steel which includes electrical, alloy, stainless, and tool steels. This type of steel needs restricted or specific chemical composition or mechanical or metallurgical properties.
Specialty tube – It refers to a wide variety of high-quality custom-made tubular products needing critical tolerances, precise dimensional control and special metallurgical properties. Specialty tubing is used in the manufacture of automotive, construction, and agricultural equipment, and in industrial applications such as hydraulic cylinders, machine parts, and printing rollers. Because of the range of industrial applications, the market typically follows general economic conditions.
Specification – It is a detailed document outlining the characteristics, requirements, and performance standards of a material used in a specific application, ensuring quality, safety, and performance. It refers to the detailed description of materials used in a product, including information on quality, dimensions, and other characteristics essential for manufacturing and assembly as outlined in the document.
Specification limits – They define the acceptable range for a product’s characteristics, as determined by the customer or organization, ensuring it meets requirements and standards. They represent the ‘voice of the customer’ and dictate what is considered acceptable against unacceptable. These limits are crucial for quality control and manufacturing, ensuring products fall within the specified boundaries. Specification limits set the boundaries for product characteristics, like dimensions, performance metrics, or other attributes.
Specifications – These are additional details (mandatory rules) as to how a resource classification system is to be applied, supplementing the framework definitions of that system. Generic specifications provided for the UNFC (United Nations Framework Classification for Resources) ensure clarity and comparability and are complementary to the source-specific requirements included in Aligned systems, as set out in the relevant Bridging document.
Specifications document – It is the specifications for the application of the United Nations Framework Classification for Resources (UNFC).
Specific carbon emission – It refers to the quantity of carbon di-oxide (CO2) released per unit of activity, such as a product, service, or fuel, and is calculated using emission factors to quantify the carbon di-oxide emissions produced. The process involves quantifying the direct and indirect emissions related to a product’s lifecycle, including fuel combustion, industrial processes, and transportation, and expressing these as a carbon footprint in carbon di-oxide equivalent (CO2e) to compare the impact of different greenhouse gases.
Specific conductance – It is also known as conductivity. It is a measure of a material’s ability to conduct electricity. It is the conductance of a solution with a volume of one cubic centimeter. This value is often denoted by the symbol ‘κ’ (kappa).
Specific consumption – It is a performance indicator of efficiency, defined as the ratio of resource input to output, commonly expressed as material used per unit of work or product. The process involves a simple calculation: divide the total material consumed by the total output , and a lower resulting value indicates higher efficiency.
Specific damping capacity – It is also known as damping index. It is a measure of a material’s ability to dissipate energy during a vibration or stress cycle. It is defined as the ratio of the energy dissipated during one cycle of vibration to the maximum elastic energy stored in the material during that same cycle. In simpler terms, it quantifies how effectively a material converts vibrational energy into heat or other forms of energy dissipation.
Specific energy – In cutting or grinding, it is the energy expended or work done in removing a unit volume of material.
Specific enthalpy – Specific enthalpy is a property of the fluid and can be expressed as h = u + p x v where ‘u’ is internal energy in kilojoule per kilogram, ‘p’ is absolute pressure in newton per square metre, and ‘v’ is specific volume in cubic metre per kilogram.
Specific enthalpy of steam – It is the total heat contained in 1 kilogram of steam. It is the sum of enthalpy of the various states, liquid (water) and gas (vapour).
Specific gas constant – It is the universal gas constant divided by the molecular weight of a gas, and it is unique to each gas.
Specific gravity – It is a dimensionless quantity defined as the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for solids and liquids is nearly always measured with respect to water at its densest (at 4 deg C). For gases, it is the ratio of the density of a gas to the density of dry air at the same temperature and pressure. The term ‘relative density’ is preferred in International System of Units, whereas the term ‘specific gravity’ is gradually being abandoned.
Specific heat – It is defined as the quantity of heat needed to raise the temperature of one unit mass of a substance by one degree. It is the quantity of heat typically expressed in joules per gram per degree Celsius or joules per kilogram per degree Celsius.
Specific heat capacity – Specific heat capacity (symbol c) of a substance is the quantity of heat which is to be added to one unit of mass of the substance in order to cause an increase of one unit in temperature. It is also referred to as Massic heat capacity or as the specific heat. More formally it is the heat capacity of a sample of the substance divided by the mass of the sample. The SI (International System of Units) unit of specific heat capacity is joule per kelvin per kilogram, e.g., the heat needed to raise the temperature of 1 kilogram of water by 1 kelvin is 4,184 joules, so the specific heat capacity of water is 4,184 joule per kelvin per kilogram. Specific heat capacity frequently varies with temperature, and is different for each state of matter.
Specific heat of steam – It is the quantity of heat necessary to increase the temperature of 1 deg C degree on a unit of mass of 1 kilogram of steam.
Specific humidity – It is the weight of water vapour in a gas water-vapour mixture per unit weight of dry gas. It is the ratio of the mass of water vapour to the total mass of an air parcel. It is essentially the weight of water vapour per unit weight of air, frequently expressed as grams of water vapour per kilogram of air. It provides a direct measure of the actual quantity of moisture in the air, regardless of temperature or pressure.
Specificity of classification – In logistic regression, it is the probability of a control being classified as a control by the prediction equation.
Specific job safety training – It is more specific than the department safety training since it focuses on the work-place area. In this matter, it is important to train in (i) identifying areas of high-risk potential, (ii) detailed working procedures for specific devices, and (iii) specialized training on operations. Special courses such as safety training for welding, crane operation, forklift operation, and first aid for electricians and lasers and radiation operation are also examples of specific job safety training.
Specific modulus – It is the material elastic modulus divided by the material density.
Specific pressure – It is also called compacting pressure. It refers to the force applied per unit area during the compaction or pressing of metal powders into a desired shape. This pressure is crucial in controlling the densification, porosity, and final properties of the compacted green part before sintering. The specific pressure is typically measured in units like megapascals (MPa).
Specific productivity – It refers to the quantity of a specific product produced per unit of time and sometimes per unit of furnace area or furnace volume in a production process. It is essentially a measure of how efficient a process is at producing a desired product relative to the resources used. In a blast furnace, specific productivity is the means for determining the blast furnace performance. It measures the efficiency which is normally expressed in tons per day per cubic meter (t/d /cum) of working volume. In some countries, in place of working volume, useful volume is considered.
Specific properties – These are the properties of the material divided by the density of the material.
Specific sliding – It is the ratio of the algebraic difference between the surface velocities of two bodies in relative motion to their sum.
Specific strength – It is the material strength divided by the material density.
Specific surface – It is the surface area of one kilogram of powder, normally expressed in square meters.
Specific volume – It is the reciprocal (1/specific gravity) of specific gravity. It refers to the volume occupied by a unit mass of a substance, essentially the inverse of density, and is frequently expressed as cubic meters per kilogram.
Specific wear rate – In journal bearings, it is the proportionality constant ‘K’ in the equation h = Kpvt, where ‘h’ is the radial wear in the bearing, ‘p’ is the apparent contact pressure, ‘v’ is the velocity of the journal, and ‘t’ is the sliding time. The constant ‘K’ has also been called the wear facto, but there are other definitions for the term wear factor which do not necessarily refer to journal bearings or derive their meanings from the above equation.
Specific weight – It is also known as the unit weight is a volume-specific quantity defined as the weight divided by the volume of a material.
Specimen – It is a test object, frequently of standard dimensions and / or configuration, which is used for destructive or non-destructive testing. One or more specimens can be cut from each unit of a sample.
Specimen chamber (electron optics) – It is the compartment located in the column of the electron microscope in which the specimen is placed for observation.
Specimen charge (electron optics) – It is the electrical charge resulting from the impingement of electrons on a non-conducting specimen.
Specimen contamination (electron optics) – It is the contamination of the specimen caused by the condensation upon it of residual vapours in the microscope under the influence of electron bombardment.
Specimen distortion (electron optics) – It is a physical change in the specimen caused by desiccation or heating by the electron beam.
Specimen grid – It is same as specimen screen.
Specimen holder (electron optics) – It is a device which supports the specimen and specimen screen in the correct position in the specimen chamber of the microscope.
Specimen screen (electron optics) – It is a disk of fine screen, normally 200-mesh stainless steel, copper, or nickel, which supports the replica or specimen support film for observation in the microscope.
Specimen stage – It is the part of the microscope which supports the specimen holder and specimen in the microscope and can be moved in a plane perpendicular to the optic axis from outside the column.
Specimen strain – It is a distortion of the specimen resulting from stresses occurring during preparation or observation. In electron metallography, strain can be caused by stretching during removal of a replica or during subsequent washing or dying.
Specking – It is discolouration of an enamel surface because of the foreign particles, dirt, or scale embedding themselves in the enamel. It can also be caused by base coat migration up through the cover coat in two coat / one fire-powder systems. It is also known as black specking.
Speckle image – It is characterized by a random, granular pattern of light and dark spots caused by the interference of coherent light waves. These patterns are frequently observed in images produced by techniques like radar, ultrasound, or laser speckle imaging, and they can act as a form of noise or, depending on the application, a feature to be analyzed.
Speckle interferometry – It is a non-destructive optical technique which is used to measure surface displacements by analyzing the interference patterns of a speckled image. It involves comparing two speckle patterns, one before and one after a deformation, to reveal the changes in surface shape and displacement.
Spect-O-Graph – It is an optical instrument for determining the concentration of metallic constituents in a metal (or alloy) by the intensity of specific wavelengths generated when the metal or alloy is thermally or electrically excited.
Spectral background – In spectroscopy, it is a signal got when no analyte is being introduced into the instrument, or a signal from a species other than that of the analyte.
Spectral band-width – It is the width of a signal’s frequency spectrum, which can be quantified by different methods, including the half peak level width or the mean square value of the instantaneous frequency variations and envelope variations. For amplitude-modulated signals, it corresponds to the mean square value of the rate of amplitude variation, while for frequency-modulated signals, it relates to the mean square value of the instantaneous frequency.
Spectral distribution curve – It is the curve showing the absolute or relative radiant power emitted or absorbed by a substance as a function of wavelength, frequency, or any other directly related variable.
Spectral line – It is a wave-length of light with a narrow energy distribution or an image of a slit formed in the focal plane of a spectrometer or photographic plate which has a narrow energy distribution approximately equal to that formed by mono-chromatic radiation.
Spectral line-width – It is the width of a signal’s frequency spectrum, typically measured as the full width at half-maximum (FWHM), and indicates the range of frequencies or wave-lengths over which light is emitted or absorbed by an object or source, such as a laser or a gas. A narrow line-width signifies a more precise, concentrated frequency range, while a wider linewidth indicates that the signal’s power is spread over a broader frequency range. Several phenomena, including the natural line-width from spontaneous emission, Doppler broadening, and phase noise, contribute to spectral line-width.
Spectral order – It is the number of the intensity maxima of a given line from the directly transmitted or specularly reflected light from a diffraction grating.
Spectral region – It is a specific portion of the spectrum which is analyzed during spectroscopic measurements, where the selection of regions can considerably affect the outcome of data interpretation and model calculations. It is important to choose regions which show variation to avoid including non-informative data, which can lead to misclassification.
Spectral resolution – It is the absolute limit of a hyperspectral imaging system’s ability to separate two adjacent monochromatic spectral features emitted by a point in the image, determined by the wave-length dispersion of the spectrograph and the sizes of the entrance and exit apertures.
Spectral separation – It is the degree of distinction between spectral X-ray measurements, which influences the transfer of noise during the decomposition of these measurements into basis coefficients. An increase in spectral separation enhances the uniqueness of basis functions, hence reducing solution noise relative to measurement noise.
Spectrochemical (spectrographic, spectrometric, spectroscopic) analysis – It is the determination of the chemical elements or compounds in a sample qualitatively, semi-quantitatively, or quantitatively by measurements of the wave-lengths and intensities of spectral lines produced by suitable excitation procedures and dispersed by a suitable optical device.
Spectro-chemistry – It is the application of spectroscopy in several fields of chemistry. It includes analysis of spectra in chemical terms, and use of spectra to derive the structure of chemical compounds, and also to qualitatively and quantitively analyze their presence in the sample. It is a method of chemical analysis which relies on the measurement of wave-lengths and intensity of electro-magnetic radiation.
Spectrogram – It is a photographic or graphic record of a spectrum.
Spectrograph – It is an optical instrument with an entrance slit and dispersing device which uses photography to record a spectral range. The radiant power passing through the optical system is integrated over time, and the quantity recorded is a function of radiant energy.
Spectrometer – It is a scientific instrument which is used to separate and measure spectral components of a physical phenomenon. Spectrometer is a broad term frequently used to describe instruments which measure a continuous variable of a phenomenon where the spectral components are somehow mixed. In visible light, a spectrometer can separate white light and measure individual narrow bands of colour, called a spectrum. A mass spectrometer measures the spectrum of the masses of the atoms or molecules present in a gas.
Spectrometric oil analysis programme (SOAP) – It is a maintenance technique which analyzes used oil samples to monitor the health of machinery components by detecting wear metals and contaminants. It uses spectroscopy to identify and quantify submicroscopic particles, like metal fragments, in the oil, providing insights into potential component failures. This allows for proactive maintenance and predictive analysis.
Spectrometer tube – It normally refers to the sample holder or cuvette within a spectrometer or spectro-photometer. This transparent tube houses the liquid or solid sample being analyzed, allowing light to pass through it for spectral analysis.
Spectrometry – It is the measurement of the interactions between light and matter, and the reactions and measurements of radiation intensity and wavelength. In other words, spectrometry is a method of studying and measuring a specific spectrum, and it’s widely used for the spectroscopic analysis of sample materials. Mass spectrometry is an example of a type of spectrometry, and it measures masses within a chemical sample through their mass-to-charge ratio.
Spectrophotometer – It is a spectrometer which measures the ratio (or a function of the ratio) of the intensity of two different wave-lengths of light. These two beams can be separated in terms of time or space, or both.
Spectroscope – It is an instrument which disperses radiation into a spectrum for visual observation.
Spectroscopy – It is the study of the absorption and emission of light and other radiation by matter. It involves the splitting of light (or more precisely electro-magnetic radiation) into its constituent wave–lengths (a spectrum), which is done in much the same way as a prism splits light into a rainbow of colours. In fact, old style spectroscopy has been carried out using a prism and photographic plates. Modern spectroscopy uses diffraction grating to disperse light, which is then projected onto charge-coupled devices (CCDs), similar to those used in digital cameras. The 2D spectra are easily extracted from this digital format and manipulated to produce 1D spectra which contain an impressive amount of useful data. Recently, the definition of spectroscopy has been expanded to also include the study of the interactions between particles such as electrons, protons, and ions, as well as their interaction with other particles as a function of their collision energy.
Spectrum – It is the ordered arrangement of electro-magnetic radiation as per the wavelength, wave number, or frequency.
Spectrum analyzer – It is an instrument which graphically displays the amplitude of signals in a narrow bandwidth across a frequency band.
Specular reflection – It is the condition in which all the incident light is reflected at the same angle as the angle of the incident light relative to the normal at the point of incidence. The reflection surface then appears bright, or mirror-like, when viewed with the naked eye. It is sometimes termed regular reflection.
Specular transmittance – It is the transmittance value got when the measured radiant energy in emission spectroscopy has passed from the source to the receiver without appreciable scattering.
Speculative resources – These are undiscovered Resources which can occur either in known types of deposits in favourable geological settings where mineral discoveries have not been made, or in types of deposits as yet unrecognized for their economic potential. If exploration confirms their existence and reveals enough information about their quantity, grade, and quality, they are reclassified as Identified resources.
Speech processing – It is the techniques for improving the intelligibility of human speech in a communications system.
Speech signal – It is an acoustic wave, or a series of air pressure variations, generated by human speech which carries linguistic information and can be converted into an electrical signal for processing. These pressure changes are the result of vocal cord vibration and the shaping of the vocal tract, forming a one-dimensional function of time which is fundamental to human communication.
Speed – Speed of an object is the magnitude of the change of its position over time or the magnitude of the change of its position per unit of time. It is hence a non-negative scalar quantity. The average speed of an object in an interval of time is the distance travelled by the object divided by the duration of the interval. The instantaneous speed is the limit of the average speed as the duration of the time interval approaches zero. Speed is the magnitude of velocity (a vector), which indicates additionally the direction of motion. Speed has the dimensions of distance divided by time. The SI (International System of Units) unit of speed is the metre per second, but the most common unit of speed in everyday usage is the kilometer per hour.
Speed control – It refers to the ability to regulate or maintain the speed of a device, machine, or system, often to a specific value or within a desired range. This can be achieved through various mechanisms, including electronic circuits, physical devices like governors, and even human-driven adjustments.
Speed controller (SC) – The speed controller is in charge of regulating the stand speed. Obviously, in order to achieve the rolling stability, the speed reference is to be coordinated with the other operations of the rolling mill.
Speed tear – It is also called speed crack. It consists of series of surface cracks perpendicular to the extruding direction. Speed tearing normally occurs in corner radii or extremities of a section and is caused by localized high temperature.
Speed gauge sensor – It is also known as a speed sensor or tachometer. It is a device which measures and displays the speed of a rotating object. These sensors are necessary for providing accurate speed readings to various systems, including speedometers, automatic transmissions, and other control system. In cold rolling mill, Speed gauge sensors are based on laser technologies or are simply encoders. In general, the use of laser technology (much more expensive) is preferred when the needed measuring precision is to be ensured also in presence of fast acceleration / declaration periods, that is, when an encoder can lose contact with the material.
Speed limit – On road traffic, it sets the legal maximum speed at which vehicles can travel on a given stretch of road. Speed limits are normally indicated on a traffic sign reflecting the maximum permitted speed, expressed as kilometers per hour.
Speed Master – The speed of the stands and of the coilers is required to be coordinated in order to ensure the stability of the mill. This is done by feed -forward controller is known as ‘Speed Master’. In order to prevent instability problems for the hot rolling process, one stand is elected as ‘pivot stand’ and the speed variations of the pivot stand are compensated in feed-forward through suitable speed variations for the other stands. In order to do this, it is fundamental to know, as precisely as possible, the ‘forward slip’ (FS) for all the stands, that is, the following coefficient representing the relation between the stand motor ‘angular speed’ (As) and the exit strip speed (Vout). This is represented by the equation FS = Vout / RAs, where R is the radius of the work roll. Normally, the FS coefficients are estimated through suitable mathematical models installed in the level 2 automation system together with its sensitivities with respect to the tension set points and the strip speed.
Speed of rolling – It refers to the velocity at which the metal stock being rolled is passed through the rolls during the process of reducing its thickness or changing its cross-section. This speed is a critical factor influencing the efficiency and quality of the rolling process.
Speed of sound – It is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. More simply, the speed of sound is how fast vibrations travel. At 20 deg C, the speed of sound in air is about 343 meters per second. It depends strongly on temperature as well as the medium through which a sound wave is propagating. At 0 deg C, the speed of sound in dry air (sea level 0.1 MPa) is around 331 meters per second.
Speed of travel – In welding, it is the speed with which a weld is made along its longitudinal axis, normally measured in meters per second.
Speed reducer – It is a sophisticated power transmission apparatus meticulously engineered to furnish controlled velocity to the driven equipment, ensuring it operates at a speed lower than that of the prime mover. Encased in a protective housing to safeguard lubricants and thwart the infiltration of extraneous elements, these reducers demand periodic assessments to sustain lubrication efficacy and avert foreign material ingress.
Speed sensor – It is an integral sensory component seamlessly integrated into a conveyor system, tasked with precisely gauging the speed of the belt or other dynamic components. Regular calibrations and meticulous checks are imperative to uphold the accuracy of speed readings, contributing to the overarching operational efficiency of the system.
Speiss – It is metallic arsenides and antimonides which result from smelting metal ores such as those of cobalt or lead.
Spelter – It is the zinc of commerce, more or less impure, cast from molten metal into slabs or ingots.
Spent acid – It is the acid which has been weakened or contaminated by use in an industrial process, such as nitration of organic compounds or metal pickling. These mixtures are often composed of the original acid (like sulphuric acid or nitric acid), water, and other organic compounds. Since spent acid is highly corrosive, it cannot be discharged directly and is to be treated to recover the acid or disposed of safely, as it poses environmental hazards.
Spent liquor – It is also called the mother liquor. It is the solution remaining after a component has been removed by a process such as filtration or more commonly crystallization. It is encountered in chemical processes. In crystallization, a solid (usually impure) is dissolved in a solvent at high temperature, taking advantage of the fact that most solids are more soluble at higher temperatures. As the solution cools, the solubility of the solute in the solvent gradually becomes lesser. The resultant solution is described as super-saturated, meaning that there is more solute dissolved in the solution than is to be predicted by its solubility at that temperature. Crystallization can then be induced from this supersaturated solution and the resultant pure crystals removed by such methods as filtration and centrifugal separators. The remaining solution, once the crystals have been filtered out, is known as the spent liquor, and contains a portion of the original solute (as predicted by its solubility at that temperature) as well as any impurities which are not filtered out. Second and third crops of crystals can then be harvested from the spent liquor.
Spent lithium-ion battery – It is the battery which has reached the end of its useful life, containing high concentrations of heavy metals and toxic flammable electrolytes, which pose substantial environmental and health risks if not managed properly.
Spent nuclear fuel – It is also called depleted nuclear fuel. It is the irradiated nuclear reactor fuel which has reached the end of its useful life to the extent that it can no longer effectively maintain a chain reaction and generate sufficient heat. Spent nuclear fuel is fuel removed from a reactor after final use. Typically, spent fuel is made up of around 96 % un-reacted uranium, 1 % plutonium, and 3 % waste products. The precise composition depends largely on the type of reactor and the quantity of power produced by the fuel.
Spent oil – It is also known as used oil. It refers to a petroleum-based or synthetic oil which has been used and, as a result, has become contaminated with impurities or has lost its original properties, making it unsuitable for its intended purpose. It is a regulated material, and its management is important to prevent environmental harm.
Spessartine – It is a nesosilicate, manganese aluminium garnet species, (Mn2+)3Al2(SiO4)3. This mineral is sometimes mistakenly referred to as spessartite.
Sphalerite – It is a zinc sulphide mineral with the chemical formula (Zn, Fe)S. It is the most common ore mineral of zinc. It is the most important ore of zinc. Sphalerite is found in a variety of deposit types, but it is mainly in sedimentary exhalative, and volcanogenic massive sulphide deposits.
Sphere – It is a geometrical object which is a three-dimensional analogue to a two-dimensional circle. Formally, a sphere is the set of points that are all at the same distance ‘r’ from a given point in three-dimensional space. This given point is the centre of the sphere, and ‘r’ is the sphere’s radius.
Sphere of influence – It refers to a region or volume around a central object or molecule where its influence (e.g., gravitational pull or attractive forces) is dominant. It is a way of defining the area within which the central entity’s effects are most significant, and other influences become less relevant.
Spherical aberration – It is the zonal aberrations of a lens referred to an axial point. When rays from a point on the axis passing through the outer lens zones are focused closer to the lens than rays passing the central zones, the lens suffers positive spherical aberration. If the condition is reversed, that is, the outer zones have a longer focal length than the inner zones, the lens has negative spherical aberration. In the first instance, the lens is uncorrected or under-corrected; in the second, overcorrected.
Spherical bearing – It is a bearing which is self-aligning by virtue of its partially spherical form.
Spherical coordinate system – It specifies a given point in three-dimensional space by using a distance and two angles as its three coordinates. These are (i) the radial distance along the line connecting the point to a fixed point called the origin, (ii) the polar angle between this radial line and a given polar axis, and (iii) the azimuthal angle, which is the angle of rotation of the radial line around the polar axis. Once the radius is fixed, the three coordinates known as a 3-tuple, provide a coordinate system on a sphere, typically called the spherical polar coordinates. The plane passing through the origin and perpendicular to the polar axis (where the polar angle is a right angle) is called the reference plane (sometimes called fundamental plane).
Spherical joint – It also known as a ball-and-socket joint. It is a mechanical connection which permits three relative rotations between two connected components. It allows a connected object to pivot in any direction about a single point while restricting translation (movement along a line). This joint is used in several applications.
Spherical mirror – It is a mirror with a curved, reflective surface which forms a part of a hollow sphere, enabling it to reflect and manipulate light in predictable ways. The two main types are concave mirrors (curving inward) and convex mirrors (curving outward), each used in applications to control how light converges or diverges for specific optical functions.
Spherical powder – It consists of globular shaped particles.
Spherical pressure vessels – These pressure vessels are normally used as storage tanks, and are recommended for storing large volumes. Since the spherical shape is the ‘natural’ form which the materials normally adopt when subjected to internal pressure, and hence spherical vessels are the most economical way for the storage of the pressurized fluids. However, the manufacture of these vessels is much more complicated and expensive compared the cylindrical pressure vessels.
Spherical projection – It is a projection in which the orientation of a crystal plane is represented by the point at which the plane normal intersects a sphere drawn with the crystal as the centre.
Spherical roller bearings – These are spherical bearings containing rollers. These are roller bearings which have a barrel shaped or hour glass-shaped rollers riding on spherical (concave or convex) races to provide self-aligning capability. These bearings have medium friction, medium to heavy loads. They are normally used for very high load applications with misaligned shafts to housings. In rolling mills, these bearings are mainly used as roll neck bearings where the demands on axial guidance accuracy are not particularly high. Since the available height is restricted, spherical roller bearings which have a small section height are used. These bearings are self-aligning. They can support radial and axial forces. Since the axial internal clearance is between four and six times the radial internal clearance, their axial guidance accuracy is low. Spherical roller bearings can be used at low and moderate speeds.
Spheroidal graphite – It is the graphite of spheroidal shape with a polycrystalline radial structure. This structure can be obtained, e.g., by adding cerium or magnesium to the melt.
Spheroidal graphite (SG) cast iron – It, also known as nodular iron or ductile iron. It is a type of cast iron where the graphite is present in the form of small, rounded nodules or spheroids, rather than flakes like in gray cast iron. This spheroidal graphite structure improves the material’s ductility, strength, and toughness compared to gray cast iron.
Spheroidal graphite iron rolls – This is a type of alloy iron rolls where the structure is completely different from that of cast iron rolls. The graphite is present in the form of spheroids or nodules which increases the ductility and makes the roll more resistant to fracture. Nodularization is achieved by the addition of calcium silicide and magnesium or cerium. The nodular structure of carbon imparts better tensile strength than that of cast iron along with better wearing properties. The spheroidal graphite iron has much greater strength and toughness, the former being about twice that of a high duty flake graphite iron and the latter is increased about twelve times. Majority of the rolls have a pearlitic structure but the acicular structure is also available giving better wear resistance. A good finish can be achieved on the rolls though care in machining is necessary as noxious fumes are given off. The wear properties of spherical graphite iron rolls are that they wear evenly and at a similar rate to flake graphite iron. They are suitable for use where a normal iron roll is not strong enough and where steel rolls give poor life due to excessive wear but, as they are more expensive than both iron and steel rolls, care in the choice of application is necessary. Hardness can be achieved up to 80 deg Shore or more. These rolls are more prone to fire-cracking and need lot of external cooling.
Spheroidal powder – It refers to metal powder particles which are shaped into smooth, round or oval particles. This shape is achieved through specific processing methods like gas or plasma atomization. Spheroidal powders offer advantages like improved flowability, uniform size distribution, and higher packing density, making them ideal for several powder metallurgy processes.
Spheroidite – It is an aggregate of iron or alloy carbides of essentially spherical shape dispersed throughout a matrix of ferrite.
Spheroidize annealing – It is the term which describes a thermal process which results in a globular or spheroidal type of carbide after heating and cooling.
Spheroidized structure – It is a micro-structure consisting of a matrix containing spheroidal particles of another constituent.
Spheroidized Vementite – It is also called divorced pearlite. It is the globular condition of iron carbide after a spheroidizing treatment.
Spheroidizing – It consists of heating and cooling to produce a spheroidal or globular form of carbide in steel. Spheroidizing methods frequently used are namely (i) prolonged holding at a temperature just below Ae1 temperature, (ii) heating and cooling alternatively between temperatures which are just above and just below Ae1 temperature, (iii) heating to a temperature above Ae1 temperature or Ae3 temperature and then cooling very slowly in the furnace or holding at a temperature just below Ae1 temperature, (iv) cooling at a suitable rate from the minimum temperature at which all carbide is dissolved to prevent the reformation of a carbide network, and then reheating in accordance with method 1 or 2 above. It is applicable to hyper-eutectoid steel containing a carbide network.
Spheroidizing annealing – It results in carbide spheroids in a ferrite matrix. The degree of spheroidization varies as per the heat-treatment temperature and holding time. It is done to get spheroid structures in steel for the improvement of the machinability and ductility. It is frequently performed for those alloy steels and high carbon steels which are to be machined or cold formed in subsequent processes. The process improves the machinability of the steels by improving the internal structure of the steels. It is beneficial when subsequent machining and / or hardening is needed, since the micro-structure consists of rounded cementite particles in a ferrite matrix. Spheroidizing annealing is normally accomplished by prolonged heating at temperatures just below the Ac1 temperature, but can be facilitated by alternately heating to temperatures just above the Ac1 temperature and cooling to just below the Ac1 temperature. The final step, however, consists of holding at a temperature just below the critical temperature Ac1. The rate of cooling is immaterial after slowly cooling to around 540 deg C. The rate of spheroidization is affected by the initial structure. The finer the pearlite, the more readily spheroidization is accomplished. A martensitic structure is very amenable to spheroidization. This treatment is normally applied to the high carbon steels (0.6 % of carbon and higher). The purpose of the treatment is to improve machinability and it is also used to condition high-carbon steel for cold-drawing into wire.
SPICE – It is a set of computer programmes for modelling the behaviour of electronic circuits.
Spicer joint – It is also known as a universal joint (U-joint). It is a mechanical joint which allows two rotating shafts to be connected at an angle to each other, enabling the transfer of rotational power. It is a type of coupling normally used in drive-shafts, particularly in vehicles where the engine’s power needs to be transmitted to the wheels at varying angles because of the suspension movement.
Spider crack – It refers to a pattern of multiple, hairline cracks radiating outwards from a central point, resembling a spider’s web. These cracks can appear in several materials indicating stress or damage.
Spiegeleisen – It is also called Spiegel. It is a pig iron which contains 15 % to 30 % manganese and 4.5 % to 6.5 % carbon.
Spiegler–Kedem model – It is a mathematical framework which describes the transport of solutes through nano-filtration membranes by integrating both diffusive and convective effects, using equations which account for solute and water flux, membrane properties, and osmotic pressure.
Spigot – It is a device which controls the flow of liquid, typically from a pipe or container. It is essentially a tap, especially those found on the outside of a building or connected to a barrel or cask. The word spiral in this context does not directly relate to the definition of a spigot, but can be used to describe the shape of something related to a spigot, like a spiral welded pipe, which is a type of pipe where the seams are welded in a spiral pattern.
Spike – It is a very brief, sharp fluctuation in an electrical signal (a voltage spike). It is also a short, high-intensity pulse in signal processing used to detect events. A spike can also refer to a specific structural element like a spike screw used to anchor railway tracks.
Spike waveform – It is a known signal shape used to detect events within a noisy environment, where its characteristics, including the spike support and shape, are fully understood. This waveform is utilized in detection systems to measure correlation with observations while accounting for noise covariance.
Spillage – It is the inadvertent release or escape of material from the conveyor, frequently triggering cleanup procedures and introducing potential hazards. Systematic inspections are indispensable to pinpoint and rectify factors contributing to spillage, ensuring a clean and hazard-free conveyor environment.
Spill-over effect – It refers to the indirect or unintended consequences of an action, event, or policy which extends beyond its original intended scope. These effects can be positive or negative, and they can occur across different domains like economics, marketing, and even computer science.
Spin – In bearings, it is the rotation of a rolling element about an axis normal to the contact surfaces.
Spin angular velocity – It is a measure of how fast a rigid body rotates around its own centre of mass or axis of rotation. It is the rate at which the object’s angular displacement changes over time. Essentially, it describes how quickly the object is spinning around its internal axis.
Spin casting – It is a foundry technique. It also called centrifugal rubber mould casting (CRMC) which uses centrifugal force to fill a rubber mould with molten metal or liquid plastic to create a cast part. In the process, a rubber mould containing a master model is spun at high speed while liquid material is poured into it. The centrifugal force, along with other forces, ensures the material fills the mould cavities, where it then solidifies under pressure to create the final casting.
Spindle – It is a rotating shaft which holds either a tool or a work-piece. It serves as the machine’s rotating axis, providing the necessary power and speed for operations like drilling, milling, grinding, or turning, ensuring accuracy and precision in manufacturing processes. The term can also refer to the entire rotary unit, including the shaft, its bearings, and any attached components like chucks.
Spindle system – It is a key component in machine tools, consisting of a spindle, bearings, a driving system, a cooling system, and housing, which collectively determine the machining accuracy and productivity through parameters such as rotational speed, power, and torque.
Spinning disk – It is a type of intensified reactor where liquid is spread into a thin film on a rotating disk under high centrifugal forces to enhance mixing, heat, and mass transfer rates for applications like chemical processing and wastewater treatment.
Spinning extrusion – It is also known as melt spinning. It is a polymer manufacturing process where a polymer, typically in pellet form, is melted, pumped through a spinneret (a die with several fine holes), and then solidified into filaments, forming yarn or fibre. The process involves extruding the molten polymer under pressure, where it cools and solidifies into a continuous filament which is then drawn and oriented to achieve its desired strength and properties.
Spin quantum number – It describes a particle’s intrinsic angular momentum, or ‘spin’, which is a fundamental property like its electric charge. It has a fixed value for each type of particle, such as +1/2 or -1/2 for an electron, representing its ‘spin up’ or ‘spin down’ orientation. This quantum number is crucial for understanding electron behaviour and the structure of atoms and molecules.
Spin transistor – It is a type of transistor which utilizes the spin orientation of electrons, involving two ferro-magnetic layers for spin injection and analysis, with output characteristics that depend on the relative magnetization of these layers.
Spin velocity – It is also known as angular velocity. It is the rate at which an object rotates or revolves around an axis, measured as the change in angle per unit time, frequently in radians per second. It describes how fast a rigid body turns, with different points on the body having the same angular velocity but varying tangential (linear) velocities depending on their distance from the axis of rotation.
Spindle – It is a shaft of a machine tool on which a cutter or grinding wheel can be mounted. It is the metal shaft to which a mounted wheel is cemented.
Spindle oil – It is an oil of low viscosity which is used to lubricate high-speed light spindles.
Spinel – It is a group of natural or synthetic minerals with the general formula R’’R’’’2O4 (or the general oxide formula R’’O· R’’’2O3) in which the R’’ is one or more bivalent cations such as magnesium or ferrous iron and R’’’ is one or more trivalent cations such as aluminum, chromium, or ferric iron. Spinel in this usage refers mainly to the crystalline structure of the material rather than the specific cations
included. It is specifically the magnesium aluminate spinel, MgAl2O4 (or MgO·Al2O3), which is 28.3 % MgO and 71.7 % Al2O3 by weight. The term also applies in a general sense to a class of compounds with a cubic crystalline structure, composed of mixtures of di-valent and tri-valent metal oxides, e.g., chromite.
Spin glass – It is one of a wide variety of materials which contain interacting atomic magnetic moments and also possess some form of disorder, in which the temperature variation of the magnetic susceptibility undergoes an abrupt change in slope at a temperature normally referred to as the freezing temperature.
Spinning – It is the forming of a seamless hollow metal part by forcing a rotating blank to conform to a shaped mandrel which rotates concentrically with the blank. In the typical application, a flat-rolled metal blank is forced against the mandrel by a blunt, rounded tool, however, other stock (notably, welded or seamless tubing) can be formed. A roller is sometimes used as the working end of the tool. Spinning is a method of forming sheet metal into seamless, axisymmetric shapes by a combination of rotation and force. On the basis of techniques used, applications, and results obtainable, the method can be divided into two categories namely manual spinning and power spinning. In power generation, spinning refers to generators which are online and synchronized with the grid, ready to increase output immediately to meet demand or compensate for outages. This ‘spinning reserve’ capacity is crucial for maintaining grid stability and reliability by providing a quick response to sudden changes in electricity supply or demand.
Spinning, hollow ware – It is a relatively new method for the centrifugal production of hollow ware such as borosilicate glass columns in chemical plants, funnels, television tubes and other non-rotationally symmetrical items. Molten glass is fed into a steel mould which rotates at the required speed. At high speeds, the glass can assume almost cylindrical shapes. When the glass has cooled sufficiently, rotation stops and the glass is removed.
Spinning nozzle inert flotation (SNIF) – It is a method used in aluminum refining to remove hydrogen, inclusions, and other impurities from molten aluminum. It involves using a spinning nozzle to generate inert gas bubbles, which then float unwanted materials to the surface of the molten metal for removal. This process is highly efficient and environmentally friendly, making it a popular choice in aluminum refining.
Spinodal curve – It is a graph of the realizable limit of the super-saturation of a solution.
Spinodal hardening – It is same as aging.
Spinning reserve – In power systems, it refers to the extra generating capacity which is online, synchronized to the grid, and ready to quickly provide additional power (within seconds to minutes) to meet sudden increases in demand or to compensate for the unexpected outage of a generator. It’s a crucial component of grid stability and reliability.
Spinodal structure – It is a fine, homogeneous mixture of two phases which form by the growth of composition waves in a solid solution during suitable heat treatment. The phases of a spinodal structure differ in composition from each other and from the parent phase, but have the same crystal structure as the parent phase.
Spinoidal hardening – It is the strengthening caused by the formation of a periodic array of coherent face-centered cubic solid-solution phases on a sub-microstructural size level.
Spin wave – It is a sinusoidal variation, propagating through a crystal lattice, of that angular momentum associated with magnetism (mostly spin angular momentum of the electrons).
Spiral angle – It refers to the angle of the teeth in spiral bevel gears, which affects thrust loading depending on the direction of rotation and whether the angle is positive or negative.
Spiral bevel gears – In spiral bevels, curved teeth provide an action somewhat like that of a helical gear. This produces smoother, quieter operation than straight-tooth bevels. Thrust loading depends on the direction of rotation and whether the spiral angle at which the teeth are cut is positive or negative.
Spiral Bourdon tube – It is a specialized form of the Bourdon tube, a common mechanical pressure sensing element, where the tube is bent into a spiral shape rather than a C-shape. This design increases the displacement of the free end of the tube, allowing it to measure higher pressure ranges and reducing the need for mechanical amplification.
Spiral classifier – It is a mechanical device used in mineral processing to separate solid particles from a slurry based on their size and density. It works by using a rotating spiral within a tank to create a continuous flow, allowing coarser, heavier particles to sink and be discharged, while finer, lighter particles are carried away in the overflow.
Spiral concentrator – It is a curved-bottom trough, wound around a vertical axis in the form of a helix. When fed at the top with a slurry of iron ore and gangue, the less dense gangue, being more readily suspended by the water, attains greater tangential velocity than the iron minerals, and migrates toward the outer rim of the spiral trough. Wash water added along the inside rim helps wash away the lighter gangue. After a few turns, a band of iron mineral forms along the inner rim, and the gangue forms bands toward the outer rim. Ports are spaced along the inner rim to collect and remove the iron minerals. Spiral concentrators are flowing film separation devices. General operation is a continuous gravitational laminar flow down on an inclined surface. The mechanism of separation involves primary and secondary flow patterns. The primary flow is essentially the slurry flowing down the spiral trough under the force of gravity. The secondary flow pattern is radial across the trough. Here the upper-most fluid layers comprising higher density particles move away from the centre while the lower-most concentrate layers of higher density particles move towards the centre. Spirals need addition of water at various points down the spiral to assist washing of the iron ore, i.e., transporting away the light gangue from the dense ore. The quantity of wash water and its distribution down the spiral trough can be adjusted to meet the operating requirements. Point control minimizes the total water requirements by efficiently directing water into the flowing pulp at the most effective angle.
Spiral flow – It is a type of swirling, helical motion where a fluid moves in a spiral, or helix, pattern, frequently observed in bends of channels, and rivers. It is also known as helicoidal flow. It is also a method using a specialized, spiral-shaped mould to measure how far a molten plastic material flows under specific conditions, which indicates the material’s mouldability and is influenced by its viscosity, temperature, and pressure.
Spiral groove – It is a helical channel formed within a structure, such as the liner of an extruder barrel, which prevents material from slipping and improves conveying efficiency in single screw extruder designs.
Spiral pipe – It is defined as a hollow structural component characterized by a helical shape, which allows for a large heat exchange area and high heat exchange efficiency, normally used in several applications. Its tightness and structural properties are influenced by parameters such as spiral diameter and pitch.
Spirals – These are gravity concentrators that use a helical structure to separate mineral particles based on their density and size. They are normally used in the mineral processing industry to concentrate low-grade ores and other industrial minerals. Spirals need addition of water at different points down the spiral to assist washing of the iron ore, i.e., transporting away the light gangue from the dense ore. The quantity of wash water and its distribution down the spiral trough can be adjusted to meet the operating requirements. Point control minimizes the total water requirements by efficiently directing water into the flowing pulp at the most effective angle. Feed size applicability is in the range of 0.3 millimeter to 1 millimeter. Spirals are normally operated at a pulp density containing 25 % to 30 % of solids.
Spiral serrated finish – It is a finish of a flange. It is similar to a stock finish but the difference between them is the way the grove is made. A 90-degree inclined angle tool is used to make the grove. It makes a grove 0.4 millimeter deep and the feed is 0.2 millimeters.
Spiral strand – It is a rope construction consisting of concentric helical layers of wire, which provides high strength and stiffness for a given diameter, along with a high degree of torque balance. Its outer surface is cylindrical, allowing for polymer sheathing to improve corrosion resistance, although it is vulnerable to damage and has manufacturing challenges.
Spiral submerged arc welded (SSAW) pipe – It is also known as spiral welded pipe. It is a type of steel pipe manufactured by forming a steel coil into a spiral shape and then welding the edges together using the submerged arc welding (SAW) process. This process involves melting the edges of the steel coil with an electric arc, and then protecting the weld area with a layer of granular flux, which prevents impurities from contaminating the weld. The resulting weld seam runs helically around the pipe’s circumference.
Spiral test – It is a method of interpreting the fluidity of an alloy by pouring molten metal into a mold with a long narrow channel. The length of such casting, under standardized conditions, is taken as the fluidity index of that alloy.
Spiral torsion spring – It is a type of mechanical spring that stores and releases energy by twisting. It is essentially a flat strip of metal wound into a spiral, with one end fixed and the other attached to a rotating component. When the spring is twisted, it stores energy, and when the twisting force is removed, it unwinds, releasing the stored energy.
Spiral welded pipe – It is also known as helical welded pipe. It is a type of steel pipe manufactured by continuously forming a steel strip into a spiral shape and welding the edges together along the seam. This process results in a spiral seam that runs along the length of the pipe. It is produced using submerged arc welding and is normally used for water distribution and other applications.
Spirit level – It is a device consisting of a sealed glass tube partially filled with alcohol or other liquid, containing an air bubble whose position reveals whether a surface is perfectly level. It is a tool which is used to determine a horizontal or vertical reference line.
Spit – It is a non-standard term for flash.
Splash core – It is a core of tile placed in a mould to prevent erosion of the mould at places where metal impinges with more than normal force. Splash cores are normally used at the bottom of large rammed pouring basins, at the bottom of long down-sprues, or at the ingates of large moulds.
Splash lubrication – It is a system of lubrication in which the lubricant is splashed onto the moving parts.
Splash zone – In marine application, it is the portion above the level of mean high tide that is subject to wetting by large droplets of sea-water.
Splat powder – It is a rapidly cooled or quenched powder whose particles have a flat shape and a small thickness compared to the other dimensions, It is similar to the flake powder.
Splat quenching – It is the process of producing splat powder.
Splay – It is a fanlike surface defect near the gate on a part.
Splice – It is the juncture or linking point between two ends of a conveyor belt, necessitating routine inspections and meticulous repairs to fortify the structural integrity and resilience of the conveyor belt splices. Splice is also the joining of two ends of glass fibre yarn or strand, normally by means of an air- drying adhesive.
Splice allowance – It is the additional length needed to make a splice. Length depends on number of plies, rectangular or bias press, belt rating, steel cord diameter and pitch etc.
Splice bars – These are also known as reinforcing bar splices. These are used in reinforced concrete structures to join two or more reinforcing bars together, ensuring a continuous and strong connection. This is essential for maintaining the structural integrity of the concrete element, as the splice transfers forces from one bar to another, preventing weak points. There are several methods for splicing, including lap splicing, mechanical splicing, and welding, each with its own advantages and suitable applications.
Splicer – A field engineer to carry out the splicing.
Splicing – It is the intricate artistry of seamlessly amalgamating two extremities of a conveyor belt, demanding a discerning application of specialized splicing techniques and fastidious inspections. This methodical approach ensures the genesis of sturdy and dependable connections within the conveyor belt, promoting its longevity and reliability.
Spline – It is a series of longitudinal, straight projections on a shaft which fit into slots on a mating part to transfer rotation to or from the shaft.
Spline fit – It is a mathematical method to draw a smooth curve through a set of data points by connecting them with a series of piecewise, low-degree polynomial functions, ensuring the overall curve is continuous and smooth at the connection points, called knots. This approach avoids the undesirable oscillations of high-degree polynomial fits and provides a more natural-looking curve compared to simple linear interpolation.
Split capacitor motor – It is a type of single-phase induction motor which uses a capacitor to create a phase difference between its two stator windings, the main and auxiliary, to induce rotation. The capacitor is permanently connected in the circuit, unlike capacitor-start motors where it is only used during the starting phase. This permanent connection provides a consistent phase shift, enabling smooth and reliable operation.
Split die – It is a die which is made of parts that can be separated for ready removal of the work-piece. It is also known as segment die.
Split flow arrangement – It is a system where a single inlet fluid stream is divided into two or more separate paths or channels before being recombined or distributed to different outlets. This configuration is used in several applications, such as distillation trays, to improve heat transfer in fired heaters, and to manage fluid distribution in heat exchangers and micro-fluidic devices. The main goal is to increase capacity, improve efficiency, or control the distribution of fluid across multiple sections.
Split-Hopkinson pressure bar (SHPB) testing of soft materials – It is a dynamic mechanical testing method which is used to characterize the stress-strain response of materials under high strain rate impact. It is particularly valuable for soft materials because of the low impedance of these materials, which needs adjustments in the split-Hopkinson pressure bar setup and data analysis.
Split nut – It is a nut which is split lengthwise into two pieces (opposed halves) so that its female thread can be opened and closed over the male thread of a bolt or leadscrew. This allows the nut, when open, to move along the screw without the screw turning (or, vice versa, to allow the screw to pass through the nut without turning). Then, when the nut is closed, it resumes the normal movement of a nut on a screw (in which axial travel is linked to rotational travel). A split nut assembly is frequently used in positioning systems. It is one of the machine elements which makes single-point threading practical on manual lathes. The two halves of the nut have chamfered ends (60-degree to the axis), which helps the threads to find engagement during the closing action. Normally, the screw and nut are also oiled for lubrication. Such provisions prolong the service life of the threads by minimizing wear. Split nuts work best with trapezoidal threads. They do not engage and disengage with multi start threads because of the overlapping leads.
Split pattern – It is a pattern which is parted for convenience in moulding.
Split phase distribution – It is a type of distribution system which uses a centre tapped transformer to provide two voltages to a building wiring system.
Split phase motor – It is a type of single-phase motor which uses a resistor, inductor, or capacitor and two windings to obtain a rotating magnetic field.
Split pipe backing – It is the backing in the form of a pipe segment which is used for welding round bars.
Split punch – It is a segmented punch or a set of punches in a powder metallurgy forming press which allow(s) a separate positioning for different powder fill heights and compact levels in dual-step and multi-step parts.
Split seal – It is a seal which has its primary sealing elements split in a plane parallel to the axis of the shaft such that, instead of the rings being continuous, they are essentially two semi-circles. Modified designs of lip seals feature units with a single lip separation and with one or more separations of the metallic stiffening mechanisms.
SPM – It is the abbreviation of suspended particulate matter.
Sponge – It is a form of metal characterized by a porous condition which is the result of the decomposition or reduction of a compound without fusion. The term is applied to forms of iron, titanium, zirconium, uranium, plutonium, and the platinum-group metals.
Sponge iron – It is also known as direct-reduced iron (DRI). It. is a form of iron which is produced by directly reducing iron ore to metallic iron without melting it. This process, called direct reduction, uses a reducing gas like natural gas or coal gas to remove oxygen from the iron ore, resulting in a porous, sponge-like material. The porous structure is because of the removal of oxygen, which creates tiny pores in the ore body.
Sponge titanium – It is a porous, crude form of the metal got from the initial production stages, typically through the Kroll process, where titanium tetra-chloride is reduced by magnesium or sodium. This intermediate, high-purity titanium material serves as the primary raw material for producing pure titanium or alloys after being melted and refined into ingots. Its unique properties, including high strength, low density, and excellent corrosion resistance, make it valuable for applications in chemical processing.
Sponge iron powder – It is also known as direct reduced iron (DRI) powder. Sponge iron is a form of iron produced by directly reducing iron ore to metallic iron. Sponge iron powder is ground and sized iron which has been purified and annealed or both.
Sponge iron process – It is also known as direct-reduced iron (DRI) production process. It is a process which converts iron ore into metallic iron by removing oxygen through a reduction reaction in solid state, typically using a reducing gas or carbon. This process results in a porous, spongy material, hence the name, and is a key alternative to traditional blast furnaces for steel production.
Sponge titanium powder – It is a fine-grained titanium product derived from titanium sponge, a raw form of titanium. This powder is created by processing the sponge through methods like crushing, milling, and sieving. The titanium sponge itself is produced by reducing titanium tetra-chloride or titanium oxides with magnesium or sodium.
Sponginess – it is a defect which occurs during the early stages of solidification of a casting and has the appearance, as the name imply, of a sponge. It is normally local or general in extent. The major cause is failure to obtain directional solidification of the casting towards the desired heat centres, such as risers and ingates, insufficiently high pouring temperature and placing of ingates adjacent to heavy sections.
Spongy – It refers to a porous condition or structure in metal powders, frequently observed in those produced from reduced oxides. These powders, like sponge iron, are characterized by internal pores within individual particles. This porosity contributes to good ‘green strength’, allowing for easy handling of the compacted powder before sintering.
Spongy casting – It is a casting in which the metal is porous and dendritic.
Spongy condition – It is a porous condition in metal powder particles normally observed in reduced oxides.
Spontaneous combustion – It is also called spontaneous ignition. It is a type of combustion which occurs by self-heating (increase in temperature due to exothermic internal reactions), followed by thermal runaway (self-heating which rapidly accelerates to high temperatures) and finally, auto-ignition. It is distinct from (but has similar practical effects to) pyrophoricity, in which a compound needs no self-heat to ignite. The correct storage of spontaneously combustible materials is extremely important, as improper storage is the main cause of spontaneous combustion. Materials such as coal, cotton, hay, and oils are to be stored at proper temperatures and moisture levels to prevent spontaneous combustion. Spontaneous combustion can occur when a substance with a relatively low ignition temperature such as hay, straw, peat, etc., begins to release heat. This may occur in several ways, either by oxidation in the presence of moisture and air, or bacterial fermentation, which generates heat. These materials are thermal insulators which prevent the escape of heat causing the temperatures of the material to rise above its ignition point. Combustion begins when a sufficient oxidizer, such as oxygen, and fuel are present to maintain the reaction into thermal runaway.
Spontaneous emission – It refers to the process where excited atoms, molecules, or free radicals in a combustion flame decay to a lower energy state, emitting a photon corresponding to the energy difference. This emission spectrum provides insights into the flame’s temperature distribution and structure.
Spontaneous emulsification – It is a low-energy process where two immiscible liquids, such as oil and water, form an emulsion without external energy input, driven by a chemical potential gradient which leads to a negative free energy of emulsification. This phenomenon typically occurs in the presence of surfactants under non-equilibrium conditions, resulting in the spontaneous formation of micro-sized emulsion droplets.
Spontaneous fission – It is a type of radioactive decay where a heavy atomic nucleus, like those in superheavy elements, splits into two or more smaller nuclei and releases neutrons and energy, without any outside trigger like neutron bombardment. This purely probabilistic process occurs because of the quantum tunneling, a natural phenomenon of quantum mechanics, and is a dominant decay mode for the heaviest elements, limiting their stability.
Spontaneous magnetization – It is the inherent ability of ferro-magnetic and ferri-magnetic materials to become naturally magnetized without an external magnetic field, occurring at temperatures below their Curie temperature. This effect results from the strong alignment of the magnetic dipoles (spins) of the atoms within the material, creating magnetic domains and leading to a net magnetic moment even when no external field is present.
Spool – It is a cylindrical device, typically with a rim or ridge at each end, on which thread, wire, tape, or other material is wound. It is a way to store and organize flexible materials in a compact and manageable form. The verb ‘to spool’ means to wind something onto a spool or to unwind something from a spool. Spool is also an assembly of fittings, flanges, and pipes in a pipeline which can be pre-fabricated. It does not include bolts, gaskets, valves, or instruments.
Spool conveyor – It is an ingenious conveyor manifestation where spools orchestrate the motion of O-rings, propelling rollers to facilitate the fluid movement of products along the conveyor route. The complex synergy among spools, O-rings, and rollers necessitates periodic assessments to guarantee optimal functionality, ensuring the uninterrupted conveyance of products.
Spool drawing – It is an orthographic drawing of a spool drawn either from piping general arrangement (GA) drawing or from an isometric drawing sheet. Each spool drawing shows only one type of spool and carries out four details namely (i) instructions for welder to fabricate the spool, (ii) list of the cut lengths of pipe, fittings, and flanges etc. needed to make the spool, (iii) material of construction and any special treatment of finished piping, and (iv) number of same type of spools needed. Spool numbers are given to make the identification easy.
Spool valve – It is a directional control valve which utilizes a cylindrical barrel and a sliding plunger to manage fluid flow through different ports, enabling multi-way and multi-position switching. The valve’s design can include seals to prevent leakage and maintain operational efficiency, with options for materials such as stainless steel or aluminum.
Sporadic distribution – It refers to something which happens infrequently, irregularly, or in scattered instances, meaning it is not frequent or regular. It is not a continuous or patterned occurrence, but rather scattered or isolated instances. For example, exogenous inclusions in steel have sporadic distribution.
Sporadic problem – It refers to an issue which occurs infrequently, irregularly, and without a predictable pattern. It is not a constant or persistent problem, but rather happens occasionally or in isolated instances. Statistically, sporadic problem is a problem when the output of a process does not conform to specification requirements even when the process is known to be capable. Such a problem is caused by a special or an assignable cause.
Spot annealing – It refers to a localized heat treatment process where only a specific, small area of a material is heated and then cooled to alter its properties, such as reducing hardness or improving ductility. This technique is frequently used to modify a particular part of a component, like repairing a specific spot or preparing it for further processing.
Spot drilling – It is the making an initial indentation in a work surface, with a drill, to serve as a centering guide in a subsequent machining process.
Spot-facing – It consists of using a rotary, hole-piloted end-facing tool to produce a flat surface normal to the axis of rotation of the tool on or slightly below the work-piece surface.
Spot market – It is the market where commodities are sold and bought for immediate delivery, differing from the futures market, which involves delivery at a later date.
Spot price – It is the current delivery price of a commodity traded in the spot market.
Spotting out – It is the delayed appearance of spots and blemishes on plated or finished surfaces which is most prevalent on porous base metals or substrates.
Spot, lube – It is a non-uniform extraneous deposit of lube on the coated sheet.
Spot weld – It is a weld made between or upon overlapping members in which coalescence can start and occur on the faying surfaces or cany proceed from the surface of one member. The weld cross section is approximately circular.
Spot welding – It is a spot weld made by either arc spot welding process or resistance spot welding process.
Spout – It is a trough through which the metal flows from the furnace to the ladle.
Spragging – It is the intermittent motion arising from design features which allow an increase in tangential force or displacement to produce an increase in normal force.
Spray – It is a dynamic collection of drops of a liquid dispersed in a gas. The process of forming a spray is known as atomization. A spray nozzle is the device used to generate a spray. The two main uses of sprays are to distribute material over a cross-section and to generate liquid surface area. There are thousands of applications in which sprays allow material to be used most efficiently. The spray characteristics needed is to be understood in order to select the most appropriate technology, optimal device and size.
Spray angle – It is the angle included between the sides of the cone formed by liquid fuel discharged from mechanical, rotary atomizers and by some forms of steam or air atomizers.
Spray casting – It is also known as spray forming or spray deposition. It is a near-net shape casting process where semi-solid metal droplets are sprayed onto a substrate to form a solid preform. The process involves melting an alloy, forcing the melt through a nozzle, and atomizing it with compressed gas, creating small, semi-solid droplets that are deposited onto a substrate. This results in a metal preform with a homogeneous microstructure.
Spray cleaning – It is cleaning by means of spraying.
Spray combustion – It is a method of burning liquid fuels which involves the atomization of the fuel into small droplets to improve heat and mass transfer during combustion. This process is characterized by a non-uniform fuel composition, where discrete liquid droplets of varying sizes interact with the gas stream, leading to irregular flame propagation.
Spray deposit – It is a coating applied by any of the thermal spray methods.
Spray deposit density (thermal spraying) – It is the ratio of the density of the spray deposit to the theoretical density of a surfacing material. It is normally expressed as a percent of theoretical density.
Spray dryer – It is a device used in the powder production process where a slurry or solution is atomized into droplets within a chamber, through which heated gases, typically air, are passed to facilitate drying.
Spray drying – It is a process which converts a liquid or slurry into a dry powder by rapidly drying small droplets in a hot gas stream. This method is widely used to produce powders from solutions or suspensions. The process involves atomizing the liquid into tiny droplets, exposing them to hot air, and then collecting the dried powder.
Spray dry scrubber – It is a flue gas desulphurization technology which involves the reaction of sulphur di-oxide (SO2) with a lime suspension in a spray absorber, achieving sulphur di-oxide removal efficiencies of up to 90 %. The technology is more economical than wet scrubbers and typically need efficient particulate control devices.
Sprayed-metal moulds – These are moulds made by spraying molten metal onto a master until a shell of pre-determined thickness is achieved. The shell is then removed and backed up with plaster, cement, casting resin, or other suitable material. These moulds are used mainly as a mould in the sheet- forming process.
Spray head – It is also known as a spray nozzle or sprinkler head. It is a device which directs and disperses a liquid, such as water, into a fine spray. It is used in various applications, including irrigation, cleaning, fire protection, and industrial processes.
Spray nozzle – It is a nozzle from which a liquid fuel is discharged in the form of a spray. It is a device which disperses a liquid into a fine mist or spray pattern, frequently used to control the flow, direction, and pattern of liquids in different industrial processes. It does this by converting the liquid’s pressure energy into kinetic energy, creating a jet or stream of liquid droplets.
Spray painting – It is a technique where a liquid solution or suspension is atomized into fine droplets and sprayed onto a substrate, creating a uniform coating which can be adjusted in thickness and is compatible with a variety of functional materials.
Spray probe – It is a device which is used to apply a fluid or gas in a controlled, localized spray pattern. This can be used for different applications, such as leak detection, material deposition, or sample introduction in scientific instruments like mass spectrometers.
Spray quenching – It is a quenching process using spray nozzles to spray water or other liquids on a part. The quench rate is controlled by the velocity and volume of liquid per unit area per unit of time of impingement.
Spray roaster – It is simply a large refractory lined steel vessel with direct-fired burners near the bottom to heat the roaster contents. The number of burners and their positions depend on the size of the roaster and the heat needed. The flame temperatures can reach in the range of 1,200 deg C to 1,750 deg C depending on the air to fuel ratio. Because of the cooling effect of the feed spray, the average temperature in the reaction zone is typically between 600 deg C to 700 deg C. In this type of pyro-hydrolysis roaster, the metal chloride solution is sprayed into the freeboard of the empty cylindrical vessel, while the required energy is supplied by the up flow of hot gases generated in the bottom burners. The spray roaster is to be designed to allow enough drying time for the largest liquid droplet to hydrolyze before reaching the bottom of the vessel. Commercial spray roasters range from 5 meters to 8 meters in height to provide this drying time. Further, the roaster diameter is to be designed for an upward gas (space) velocity which is high enough to prevent droplets from wetting the bottom of the vessel, but low enough to prevent high dust losses to the off-gas system. The space velocity is typically 0.3 meter per second to 1 meter per second for commercial units and can be even lower for smaller units. Spray roasters typically have very large diameters to keep the gas velocities low. If the gas velocity becomes too high, too many particles are carried away with the roaster off-gas, and the product quality and the efficiency of the roaster drop. In the spray roaster, the off-gas and oxides leave the roaster counter-currently at around 400 deg C to 500 deg C. Because of the counter-current flow, the exit temperature in the spray roaster is less than the reaction zone temperature.
Spray roaster process – Among all known processes for hydrochloric acid regeneration such as crystallization and fluid bed pyro-hydrolysis, the spray roaster process is the most feasible in terms of energy consumption, operating cost, maintenance cost, availability, and by-product-marketability.The spray roaster process is a pyro-hydrolytic process in which the spent acid is spray atomized into a directly fired furnace (by contact with oxygen) and splitted into ferric oxide powder (solid phase) and hydrochloric acid (gas phase). The gaseous hydrochloric acid is absorbed in water to form regenerated hydrochloric acid of around 18 % strength which can be reused for pickling. It is common and attractive to use the slightly acidic rinse water from the pickling line as absorption liquid.
Spray saturator – It is a device which saturates a gas with the vapour of a liquid by spraying the liquid into the gas. The process involves spraying the liquid, typically through a nozzle, to increase the contact surface area between the liquid and the gas, facilitating efficient saturation. This is frequently used in applications like air humidification, gas conditioning, or ammonia recovery in coke oven by-product plant.
Spray torch – It is also known as a flame spray gun. It is a device used in thermal spraying which produces a high-temperature flame to melt or soften a feedstock material, such as a wire, powder, or ceramic cord. This molten material is then propelled onto a substrate to form a protective or functional coating. The flame is generated by combusting fuel gases like acetylene, propane, or hydrogen with oxygen, with the feedstock being introduced into the flame for melting and acceleration.
Spray transfer – In consumable-electrode arc welding, it is a type of metal transfer in which the molten filler metal is propelled across the arc as fine droplets.
Spray type saturator process – In this process, the coke oven gas is directed into the spray type saturator. The ammonium sulphate lye inside the saturator is continuously sprayed into the coke oven gas in order to wash out the ammonia. The water saturated coke oven gas containing hydrogen sulphide / hydrogen cyanide is leaving the saturator with a temperature of around 95 deg C at the top. After a downstream arranged vapour cooler with inside drop separators, the vapours are cooled down to a temperature of around 60 deg C and flow to the Stretford unit for the removal of hydrogen sulphide from the coke oven gas. The circulating ammonium sulphate lye inside the saturator is directed through overflow pots and circulating pumps back to the saturator to protect the lye inside the saturator against clogging. Discontinuously, a stream from the bottom of the saturator is taken out by means of an ejector and flows through the slurry cone to the centrifuge. Inside the centrifuge the sulphate grains are cleaned from the diluted sulphuric acid, dewatered and dried in a steam heated dryer and stored in a salt store.
Spray-up – It is a technique in which a spray gun is used as an applicator tool. In reinforced plastics, for example, fibrous glass and resin can be simultaneously deposited in a mould. In essence, roving is fed through a chopper and ejected into a resin stream which is directed at the mould by either of two spray systems. In foamed plastics, fast-reacting urethane foams or epoxy foams are fed in liquid streams to the gun and sprayed on the surface. On contact, the liquid starts to foam.
Spread – Deformation along the roll-axis or transverse direction is called spread. It depends on workability and width to thickness ratio of rolling / forging and frictional conditions. Excessive spread can cause edge cracking. In composites, spread is the quantity of adhesive per unit joint area applied to an adherend, normally expressed in kilograms of adhesive per thousand square meters of joint area. In statistics, spread means that majority of the data sets show variability i.e., all the values are not the same. Two important aspects of the distribution of values are particularly important, they are the centre, and the spread. The ‘centre’ is a typical value around which the data are located. The mean and median are examples of typical values. The spread describes the distance of the individual values from the centre. The range (maximum – minimum) and the inter-quartile range (upper quartile – lower quartile) are two summary measures of the spread of the data. The standard deviation is another summary measure of spread.
Spreader – It is an axial groove in a plain bearing designed to spread oil along the bearing.
Spreader pockets – These are depressions in a sliding surface designed to distribute lubricant.
Spread footing – It is also known as an isolated footing or pad footing. It is a type of shallow foundation which is used to support individual columns or isolated loads by distributing the structural load over a larger area of soil, preventing settlement or tilting.
Spreading coefficient – It is a thermodynamic quantity which indicates whether a liquid is going to spread on a surface (either another liquid or a solid). It is defined as the difference between the work of adhesion (the forces attracting the spreading liquid to the surface) and the work of cohesion (the forces within the spreading liquid itself). A positive spreading coefficient signifies that the liquid is going to spread, creating a thin film, while a negative value means the liquid is not gong to spread, instead forming a lens or droplet.
Spreadsheet analysis – It is the process of systematically using spreadsheet software to organize, manipulate, calculate, visualize, and interpret data to extract meaningful insights and support decision-making. It involves entering data into rows and columns, applying formulas for calculations, creating charts to visualize trends, and performing ‘what-if’ analyses to understand the impact of changing variables. This analytical approach is fundamental across several professional fields.
Spring – It is an elastic object which is used to exert a force or a torque and, at the same time, to store mechanical energy. Springs are elastic bodies (normally of metals) which can be twisted, pulled, or stretched by some force. They can return to their original shape when the force is released. In other words, a spring is also termed as a resilient member. The energy expended in deforming the spring is stored in it and can be recovered when the spring returns to its original shape. Normally, the quantity of the shape change is directly related to the quantity of force exerted. However, if too large a force is applied, then the spring permanently deforms and never returns to its original shape. Springs are crucial in different systems, providing stability, support, and motion control. They come in diverse types, such as coil, leaf, and torsion springs, each with unique characteristics and applications.
Spring adjuster – It is a fitting, normally threaded on the actuator stem or into the yoke, to adjust the spring compression.
Spring-back – It is the elastic recovery of metal after stressing. It is also the extent to which metal tends to return to its original shape or contour after undergoing a forming operation. This is compensated for by overbending or by a secondary operation of restriking. In flash, upset, or pressure welding, spring-back is the deflection in the welding machine caused by the upset pressure.
Spring balance – It is also known as a spring scale. It is a device which measures force or weight by using a spring’s proportional stretch or compression against a calibrated scale. An object hung on its hook causes the spring to stretch, and the pointer indicates the weight or force on the scale, which is calibrated in units like Newtons, grams, or kilograms. The principle behind a spring balance is Hooke’s law, which states that the extension of a spring is directly proportional to the force applied.
Spring constant – It is frequently denoted by ‘k’. It is a measure of a spring’s stiffness. It quantifies the force needed to stretch or compress a spring by a certain distance. Essentially, it describes how much resistance a spring offers to deformation. Spring constant is normally the number of kilograms needed to compress a spring or sample to 25 millimeters in a prescribed test procedure.
Spring force – It is the restoring force exerted by a spring when it is compressed or stretched. This force always opposes the displacement from the spring’s relaxed state, meaning it pulls back to the equilibrium position when compressed and pushes back when stretched. The magnitude of this force is directly proportional to the displacement, as described by Hooke’s Law.
Spring-loaded axle – It is a marvelously designed roller conveyor axle featuring ingenious spring-loaded attributes, allowing the facile removal of rollers from the conveyor sans the need for comprehensive disassembly. Routine checks are indispensable to validate the seamless operation of the spring-loaded axle, thereby streamlining efficient roller maintenance procedures.
Spring rate – It is the force change per unit change in length of a spring. In diaphragm actuators, the spring rate is normally stated in newtons per millimeter of compression.
Spring scale – It is also known as a spring balance or Newton meter. It is a device which measures the weight or force exerted on an object. It utilizes a spring which stretches or compresses in proportion to the applied force, and a calibrated scale or pointer indicates the measured value. Spring scales are normally used for many applications, including weighing items, measuring force, and in scientific and educational settings.
Spring seat – It is a plate to hold the spring in position and to provide a flat surface for the spring adjuster to contact.
Spring steels – These steels are used for the manufacturer of springs. Depending on the type and application of the spring, the steel composition can vary from a plain carbon type, to carbon-silicon type, to any of a range of alloy steels and if necessary to the use of a martensitic or austenitic stainless-steel grade. These steels are produced to very high yield strengths. Spring steels are also used when there are special requirements on rigidity or abrasion resistance. These steels are also to meet the different requirements from the technical point of view. These requirements are (i) high elastic limit which is the tension that can be applied on the steel material without a plastic deformation, (ii) high ultimate strain which is the value of the extension until rupture in relation to the original length, (iii) high contraction at fracture which is the change of the original cross section in comparison to the cross section at rupture, (iv) good creep rupture strength which is a kind of tensile strength taking in account temperature and time, (v) good endurance limit which is the reaction of the material on constantly changing maximum stresses till the plastic deformation begins, and (vi) low surface decarburization and a clean, free from fracture surface makes the outer shell of the material soft hence it is to be avoided. These special requirements of spring steels are being met by adding different alloying elements in the steels. These are silicon, manganese, chromium, vanadium, molybdenum and nickel (in case of stainless steels). Most of the spring steels are hardened and tempered to around 45 HRC (Rockwell hardness ‘C’ scale). The alloy steel springs are made from either alloy steels or from stainless steels. Alloy spring steels are used for conditions of high stress and shock or impact loadings. These steels can withstand a wider temperature variation than high carbon spring steels and are used in either the annealed or pre tempered conditions. Silicon is the key element in most of the alloy spring steels. A typical example of alloy spring steel contains 1.5 % to 1.8 % silicon, 0.7 % to 1 % manganese, and 0.52 % to 0.6 % carbon.
Spring stiffness – It refers to the proportional relationship between the elastic force or torque generated by a spring and its deformation, characterized as translatory spring stiffness for linear motion and rotary spring stiffness for rotational motion.
Spring temper – It is a temper of non-ferrous alloys and some ferrous alloys which is characterized by tensile strength and hardness around two-thirds of the way from full hard to extra spring temper.
Spring up offset tooling – It is a type of press brake tooling used to create offset bends (also known as jogs) in sheet metal, specifically when the bends are too close together for standard tooling. It is characterized by the material moving from a horizontal plane up to the bend angle, similar to a regular V-bend, but with the rear of the work-piece moving downwards instead of upwards. This design helps to minimize horizontal thrust forces during the bending process.
Spring washer – It is used to apply a constant tensile force along the axis of a fastener.
Sprinkler cooling system – It utilizes water sprayed as droplets to cool down an area or object. This method is used in several applications, including hot object cooling, fire suppression, and even cooling buildings or structures. The cooling effect is achieved through the evaporation of the water, which absorbs heat from the surrounding environment.
Sprinkler head – It is a component which sprays water to lower temperatures. This can be achieved through evaporation cooling or by directly wetting surfaces to dissipate heat. In fire suppression systems, sprinkler heads are specifically designed to detect and release water to extinguish fires, with some heads also having a cooling effect on the surrounding area.
Sprocket – It is an intricately toothed wheel seamlessly integrated into chain-driven conveyor systems, prompting the need for periodic evaluations to affirm its immaculate condition, precise alignment, and overarching functionality within the system. Sprockets for engineering steel chain are designed to accept chain elongation from wear of 3 % to 6 %. When the chain elongates beyond this point, it no longer fits the sprockets and the system does not operate properly.
Sprocket teeth – These are the individual, toothed projections or notches on the outer rim of a sprocket, which is a wheel designed to engage with the links of a chain or perforations in a belt to transfer motion and power. These teeth are critical for the functioning of chain drives in machinery, transferring rotational force from one sprocket to another through a common chain.
Sprue – It is the mould channel which connects the pouring basin with the runner or, in the absence of a pouring basin, directly into which molten metal is poured. It is a vertical passageway which takes the molten metal from the pouring basin to the runner. Sprue is sometimes used to mean all gates, risers, runners, and similar scrap which are removed from castings after shakeout. Sprue is the main feed channel which runs from the outer face of an injection or transfer mould to the mould gate in a single cavity mould or to runners in a multiple cavity mould. It is the piece of material formed or partially cured in the primary feed channel. In composites, sprue is a single hole through which thermoset moulding compounds are injected directly into the mould cavity.
Sprue (down-sprue, down-gate) – It is the channel, normally vertical, through which the molten metal enters. It is so-called since it conducts metal down into the mould. It is also the vertical channel connecting the pouring basin with the runner system and terminates in the sprue well at the bottom.
Sprue base or well – It is the rectangular or cylindrical block which receives metal from the sprue, reduces the velocity of the falling stream of metal and provides the transition from the vertical to the horizontal and send the metal into the runner system.
Sprue bottom – It is a print attached to the top or squeeze board of a mould to make an impression in the cope indicating where the sprue is to be cut.
Sprue cutter – It is a metal tool used in cutting the pouring aperture, the sprue hole.
Sprue hole – It is the opening through which the metal is poured into the cope to run into the casting cavity.
Sprue pin – In die-casting, it is a tapered pin with a rounded end projecting into a sprue hole, acting as a core which deflects the metal and aids in removal of the sprue from the die-casting.
Sprue plug – It is a tapered metal or wood pin used to form the sprue opening in a mould. It is also a metal or other stopper used in pouring basin to prevent molten metal from flowing into the sprue until a certain level has been reached. It prevents entry of dirt and dross.
Spruing – It is removing gates and risers from castings after the metal has solidified.
Sprue mark – It is a mark, normally elevated, left on the surface of an injection or transfer moulded part, after removal of the sprue.
Sprung mass – In a vehicle with a suspension, such as an automobile, It is the portion of the vehicle’s total mass which is supported by the suspension, including in most applications approximately half of the weight of the suspension itself. The sprung mass typically includes the body, frame, the internal components, passengers, and cargo, but does not include the mass of the components at the other end of the suspension components (including the wheels, wheel bearings, brake rotors, calipers, and / or continuous tracks, if any), which are part of the vehicle’s unsprung mass. The larger the ratio of sprung mass to unsprung mass, the less the body and vehicle occupants are affected by bumps, dips, and other surface imperfections such as small bridges. However, a large sprung mass to unsprung mass ratio can also be deleterious to vehicle control.
Spudding – It is the driving of a short and stout section of pile-like material into the ground to punch through or break up hard ground strata to permit pile driving. It is used extensively in the driving of timber piles.
Spun fibre – It is a continuous thread created by twisting together shorter, discontinuous lengths of fibre, known as staple fibres, which can be natural (like cotton or wool) or synthetic (like polyester). This process forms a cohesive yarn, which is then used to weave into fabrics or for other textile applications, resulting in a soft, textured product with good breathability.
Spun roving – It is a heavy, low-cost glass or aramid fibre strand consisting of filaments which are continuous but doubled back on themselves.
Spur – It is a designated segment within a conveyor system strategically designated for the seamless diversion of unit loads to and from the mainline. Regular inspections stand as a cornerstone to guarantee the peak performance and unwavering reliability of this specialized spur section. In railways, spur refers to a short branch track that connects to a main line, frequently used for accessing industrial or commercial areas. It is essentially a stub track which allows loading and unloading of railcars without interfering with the main line traffic.
Spur gears – These gears have straight teeth cut parallel to the rotational axis. These gears transmit rotation between parallel shafts. The tooth form is based on the involute curve. Practice has shown that this design accommodates mostly rolling, rather than sliding, contact of the tooth surfaces. The involute curve is generated during gear machining processes using gear cutters with straight sides. Near the root of the tooth, however, the tool traces a trochoidal path, providing a heavier, and stronger, root section. Because of this geometry, contact between the teeth occurs mostly as rolling rather than sliding. Since less heat is produced by this rolling action, mechanical efficiency of spur gears is high, often up to 99%. Some sliding does occur, however. And because contact is simultaneous across the entire width of the meshing teeth, a continuous series of shocks is produced by the gear. These rapid shocks result in some objectionable operating noise and vibration. Moreover, tooth wear results from shock loads at high speeds. Noise and wear can be minimized with proper lubrication, which reduces tooth surface contact and engagement shock loads. Spur gears are the least expensive to manufacture and the most commonly used, especially for drives with parallel shafts. The three main classes of spur gears are (i) external tooth, (ii) internal tooth, and (iii) rack-and-pinion.
Sputtering – It is also called sputter deposition. It is the bombardment of a solid surface with a flux of energetic particles (ions) that results in the ejection of atomic species. The ejected material may be used as a source for deposition.
Sputtering yield – It is the measure of how much material is removed from a target surface when bombarded by energetic particles. It’s defined as the average number of atoms ejected (sputtered) from the target per incident particle (like an ion). It is defined as the average number of atoms ejected (sputtered) from the target per incident particle (like an ion).
SQL – It stands for Structured Query Language. It is a domain-specific programming language designed for managing and manipulating relational databases. It provides a standardized way to interact with data stored in tables, allowing users to perform different operations.
Square – It is a two-dimensional geometric shape with four equal sides and four right angles (90-degrees). It is a special type of rectangle where all sides are equal. In mathematics, squares are fundamental in geometry, mensuration, and coordinate geometry.
Square bar – It is a solid metal bar with a square cross-section, meaning all four sides are equal in length. It is typically made of steel but can also be found in other materials like aluminum or brass. Square bars are known for their strength, versatility, and ease of fabrication, making them suitable for a wide range of applications.
Square channel – It is a conduit or hollow section with a square cross-section, meaning its width and height are equal. This geometry is used in several engineering fields, such as for structural steel tubes (hollow steel sections), prefabricated drainage systems, and in microfluidic devices for controlled liquid or gas flow, where the precise dimensions affect performance substantially.
Squared differences – These refer to the results got by taking the differences between each data point and the mean, squaring these differences to ensure they are positive, and emphasizing larger deviations. This concept is integral to calculating variance, which represents the dispersion of data from its mean value.
Squared error loss (SEL) – It is also known as mean squared error (MSE). It is a common loss function used in machine learning, particularly for regression tasks. It quantifies the average squared difference between predicted and actual values, penalizing larger errors more heavily.
Square drilling – It is the making of square holes by means of a specially constructed drill made to rotate and also to oscillate so as to follow accurately the periphery of a square guide bushing or template.
Square gears – Gears which are square have four lobes, so they produce eight periods of speed increase or decrease per revolution. Square gears have a smaller range of speed ratios than elliptical gears.
Square groove weld – It is a type of groove weld.
Squareness – It refers to the property of being shaped like a square, characterized by four equal sides and four right angles. It can also be used to describe the degree to which something is aligned or perpendicular to a reference plane or axis. In engineering, squareness can be used to assess the alignment of parts or components, with deviations indicating misalignment.
Square root – Square-root of a number is a value which, when multiplied by itself, equals the original number. It is the inverse operation of squaring a number.
Square wave – It is a waveform which spends equal times at the positive and negative peak values with rapid transitions between them.
Squaring arms – Squaring arms are extensions attached to the entrance side of a shearing machine which are used to locate long sections of work metal in the proper position for shearing. Each arm is provided with a linear scale and with stops for accurate, consistent positioning of the work metal. Squaring arms are reversible to allow use of the shear at either end and to more evenly distribute the wear on the shear blades. Power operation can be added to the squaring arm for increasing blank accuracy and reducing the set-up time. This type of squaring arm prevents the arm from moving from side to side.
Squaring shear – It is a machining tool, used for cutting sheet metal or plate, consisting essentially of a fixed cutting knife (normally mounted on the rear of the bed) and another cutting knife mounted on the front of a reciprocally moving crosshead, which is guided vertically in side housings. Corner angles are normally 90-degree.
Squeeze board – It is a board which used on the cope half of the mould to permit squeezing of the mould.
Squeeze casting – It is a hybrid liquid metal forging process in which liquid metal is forced into a permanent mould by a hydraulic press.
Squeeze effect – It is also called sponge effect. It is the production of lubricant from a porous retainer by application of pressure. It is also the persistence of a film of fluid between two surfaces which approach each other in the direction of their common normal.
Squeeze film effect – It describes the damping and resistance to motion which occurs when a thin film of fluid (like air) is squeezed between two moving surfaces. This effect is a result of pressure changes within the fluid film as the surfaces approach or recede from each other.
Squeeze forming – It is also known as squeeze casting. It is a metal forming process which combines casting and forging in a single step. It involves pouring liquid metal into a preheated, lubricated die and applying pressure as the metal solidifies, resulting in a near-net shape part with high mechanical properties. This process is also referred to as liquid forging because of the use of pressure on the liquid metal during solidification.
Squeeze head – In certain type of moulding machines, it is a stationary or movable plate against which a filled mould is compressed, in order to complete the compacting of the sand.
Squeeze pressure – It is the pressure applied by a moulding machine to press the flask and contained sand against the fixed squeeze head or board on a moulding machine.
Squeezer machine – It is a power-operated, normally pneumatic, device used to pack sand into a flask.
Squirrel cage induction motor – It is a type of alternating current induction motor where the rotor consists of a cylindrical structure of conductive bars short-circuited at both ends by end rings, forming a cage-like appearance. This simple, rugged design makes it the most common type of induction motor, known for its low cost and reliable operation, though it has limited starting torque and speed control capabilities.
SR-KCB process – It is a smelting reduction method which directly uses chromium ore sand to produce high-chromium steel. It is a process which offers a high scrap melting capability and does not rely on expensive ferro-chrome alloys. The SR-KCB process is particularly effective in rapidly decarburizing high-carbon melts, frequently exceeding 5 % carbon, through strong stirring and large dilution gas flow rates.
Stability – It refers to a structure or system’s ability to maintain its equilibrium state and resist deformation or collapse under external loads and disturbances. It is about a system’s tendency to return to its original state after being disturbed, or to remain relatively unchanged despite external forces. A stable system maintains bounded outputs for bounded inputs, meaning it doesn’t exhibit unbounded or diverging behaviour. Stability is crucial for the safe and reliable performance of structures like buildings, bridges, and other engineering systems.
Stability analysis – It refers to the evaluation of how a product’s properties (like purity, and physical characteristics) change over time and under different storage conditions. It helps determine the shelf life of a product by assessing the rate of degradation or change. Essentially, it is about understanding how stable a product is and predicting its shelf life.
Stability theory – It is the systematic study of control systems which deals with their response to disturbances.
Stabilization – It refers to processes which improve the structural and / or chemical stability of a metal or alloy, frequently by preventing unwanted transformations or changes. This can involve heat treatment, the addition of specific elements (stabilizers), or other techniques to achieve a desired micro-structure and / or chemical composition. It also refers to techniques used to modify and improve the engineering properties of soils, making them more suitable for construction or other applications. This involves improving strength, bearing capacity, and durability to withstand loads and environmental conditions. Stabilization can be achieved through different methods, including physical, chemical, or mechanical processes. In carbon fibre forming, stabilization is the process which is used to render the carbon fibre precursor infusible prior to carbonization.
Stabilization tank – It is also known as a stabilization pond or oxidation pond. It is a large, shallow basin used for waste-water treatment. It utilizes natural processes like sunlight, algae, and bacteria to remove organic matter and pathogens from waste-water. These ponds are cost-effective and energy-efficient, making them a popular choice for waste-water treatment in countries and areas with warm climates.
Stabilization treatment – It refers to the processes which stabilize hazardous wastes by reducing the leachability of contaminants through chemical or physical means.
Stabilized soil – It refers to soil which has undergone treatment through mechanical or chemical methods to improve its engineering properties, such as strength, compressibility, and durability, making it suitable for construction applications. This process frequently involves the addition of materials like lime or cement, which improve load-bearing capacity and reduce susceptibility to settlement.
Stabilizer – It is a chemical which is used to prevent or retard degradation of rubber polymer by heat, light, or atmospheric exposure.
Stabilizer element – It is a substance added to a material to prevent its degradation and maintain its physical and chemical properties over time and under different conditions. In chemistry, stabilizers protect plastics from heat, ultra-violet light, and mechanical stress, acting as antioxidants, or flame retardants. In other contexts, a stabilizer element can be a material like aluminum or gallium used in alloys to maintain a specific crystalline structure, or it can refer to a mathematical concept describing a subset of a group which leaves a specific element fixed under its action.
Stabilizing – It is a low-temperature thermal treatment designed to prevent age softening in certain strain-hardened alloys containing magnesium.
Stabilizing gas – In plasma spraying, it is the arc gas, which is ionized to form the plasma. Introduced into the arc chamber tangentially, the relatively cold gas chills the outer surface of the arc stream, tending to constrict the arc, raise its temperature, and force it out of the front anode nozzle in a steady, relatively unfluctuating stream.
Stabilizing treatment – Before finishing to final dimensions, it consists of repeatedly heating a ferrous or non-ferrous part to or slightly above its normal operating temperature and then cooling to room temperature to ensure dimensional stability in service. It is also transforming retained austenite in quenched hardenable steels, normally by cold treatment. It also consists of heating a solution-treated stabilized grade of austenitic stainless steel to 870 deg C to 900 deg C to precipitate all carbon as titanium carbide, niobium carbide, or tantalum carbide, so that sensitization is avoided on subsequent exposure to high temperature.
Stable polynomial – It is that class of polynomials representing the transfer functions of stable control systems.
Stable vapour film – It is a continuous, protective layer of vapour which forms on a hot surface immersed in a liquid, preventing direct contact between the liquid and the surface. This film forms at high surface temperatures, such as in the film boiling regime, and can be sustained by forces like surface tension and thermocapillary flow in certain conditions, such as microgravity.
Stack – It is a vertical conduit, which because of the difference in density between internal and external gases, creates a draft at its base. It refers to a tall, vertical structure (like a chimney) used to discharge combustion gases from industrial or power plants into the atmosphere. These gases, frequently called flue gas or stack gas, are the by-products of burning fuels like coal, oil, or natural gas. In computer science, it is a linear data structure which follows a LIFO (Last-In, First-Out) principle, meaning the last element added is the first one removed, like a stack of plates. In material storage, stack refers to the arranged materials in an orderly pile or heap, frequently on top of each other. In a blast furnace, stack is the furnace volume between belly and the throat.
Stack cutting – It is thermal cutting of stacked metal plates arranged so that all the plates are severed by a single cut.
Stack draft – It is the magnitude of the draft measured at the inlet to the stack.
Stack effect – It is that portion of a pressure differential which results from difference in elevation of the points of measurement.
Stack effluent – It is the gas and solid products discharged from stacks.
Stacker – It is conveyor piling bulk material. It is frequently being referred as stacker machine. The stacker is used for preparing the stockpile with the incoming material. The machine travels on rails with the material fed to it through the yard conveyor between the rails. It is provided with a boom with a belt conveyor which is moved up and down with the help of wire ropes or a hydraulic system. Depending on the application, the entire boom system can also be slewed on the sub-structure which travels on wheels running on the rails. The material coming on the yard conveyor is raised by a tripper attached to the stacker and discharged into the boom conveyor which carries the material up to its end and allows it to fall to form a stockpile. The stacker travels continuously to and fro so that the pile is built up layer by layer.
Stacker cum reclaimer – It is also called combined stacker and reclaimer. It can stack the material to form the stockpile or reclaim the stockpiled material and feed onto the main line conveyor. The stacker is mounted on the centre column, which allows rotation in both directions simultaneously with the vertical movement of the boom. Its height above the crest of the pile is kept at a minimum to reduce dust emission. Reclaiming takes place at the natural angle of slide. A raking harrow is mounted on the bridge reclaimer. The sweeping movements of the harrow system cause the material to slide to the base, where the chain system then conveys it to the centrally placed outlet hopper. The homogenized material leaves the stockyard by an underground belt conveyor. To loosen sticky and non-free flowing materials active live-harrows are available. Stacker cum reclaimer normally consist of seven main assembly groups namely (i) set of travel gear bogies, (ii) sub-structure, super-structure with slew assembly, (iv) bucket wheel boom and bucket wheel body, (v) pylon or mast and counter weight boom , (vi) tripper and intermediate conveyor structure, and (vii) conveyor systems for boom, tripper and intermediate conveyor. The stacker cum reclaimer is mounted on rails. The weight of the stacker cum reclaimer is shared by travel bogies, in accordance with permissible wheel load.
Stacking – In material storage, stacking refers to arranging materials in an orderly pile or heap, frequently on top of each other, for efficient storage and retrieval. This method, also known as block stacking, is a common approach for storing goods in warehouses and construction sites. In open pile storage for bulk materials, the most commonly used stacking methods for making longitudinal stockpiles are cone Shell, chevron and windrow. Basically, these methods consist of stacking a large number of layers on top of each other in the longitudinal direction of the pile. Stacking in a covered stockyard (A-frame building) can be done by a simple tripper car. The tripper car is installed in a structure suspended from the building roof. The travel of the tripper car is PLC (programmable logic controller) controlled and programmed to build either a cone shell or a chevron stockpile.
Stacking and bundling machines – After cooling, rolled bars / sections are typically straightened in a roller straightener and cut to sale length by a cold shear and then they are either stacked or bundled in stacking and bundling machines. In case of stacking of angles, they are stacked in a two down, one up arrangement.
Stacking factor – It is a measure of the efficiency of filling the space of a machine core or winding. It is the proportion of active material in any given unit cross section.
Stacking fault – It is a planar defect in a crystalline structure where the regular stacking sequence of atomic planes is interrupted, resulting in a local region where the lattice is out of sequence. This disruption can lead to various material properties, including the movement of partial dislocations, the ease of deformation, and the formation of twins.
Stacking fault energy (SFE) – It is a measure of the energy associated with a stacking fault in a crystal, specifically the energy increase per unit area caused by a local deviation in the stacking sequence of atomic layers. It’s a crucial parameter that influences how materials deform, especially in face-centered cubic (fcc) and hexagonal close-packed (hcp) structures.
Stacking fault tetrahedra (SFT) – These are structures formed by stacking faults on the four {111}-type tetrahedral faces, interconnected by stair rod dislocations, typically occurring in face-centered cubic (fcc) metals with low stacking-fault energy such as gold, silver, or copper. Their strain contrast is mainly influenced by the stacking-fault areas, which can result in a distinct fringe pattern under certain conditions.
Stacking methods – These are the methods which are used in building open storage piles. The most commonly used stacking methods for making longitudinal stockpiles are cone Shell, chevron and windrow. Basically, these methods consist of stacking a large number of layers on top of each other in the longitudinal direction of the pile. In open pile storage different methods of stacking can be used.
Stacking sequence – It is a description of a laminate which details the ply orientations and their sequence in the laminate.
Stack moulding – It is a foundry practice which makes use of both faces of a mould section, one face acting as the drag and the other as the cope. Sections, when assembled to other similar sections, form several tiers of mould cavities, all castings being poured together through a common sprue.
Staffing – It is a critical organizational function which consists of the process of acquiring, deploying, and retaining a work-force of sufficient quantity and quality to create positive impacts on the effectiveness of the organization. It is one of the significant functions of the management. Staffing is that part of the process of management which is concerned with acquiring, developing, employing, appraising, remunerating and retaining people so that right type of people is available at the right positions and at the right time in the organization. In the simplest terms, staffing in management is ‘putting people to jobs’. Staffing function of the management is an important function and it involves in the building of the organizational work-force. In staffing, the management is faced with the challenge of not only finding the right person for each job but also to match the personnel with the jobs identified and to provide for their long-range growth and welfare as members of the organization.
Stage – It is a device for holding a sample in the desired position in the optical path.
Staged air burner – In it, combustion air is introduced at different locations or times relative to the fuel, typically to reduce nitrogen oxides (NOx) emissions and improve combustion efficiency. This is achieved by dividing the combustion process into multiple stages, with varying fuel-to-air ratios in each stage.
Staged fuel burner – It involves introducing fuel in stages, creating separate fuel-rich and fuel-lean zones within the combustion chamber. This technique helps to reduce nitrogen oxides (NOx) emissions by lowering peak flame temperatures and optimizing the combustion process.
Staged combustion – It is a method which is used to reduce the emission of nitrogen oxides (NOx) during combustion. There are two methods for staged combustion namely air staged supply and fuel staged supply. Applications of staged combustion include boilers.
Stage evaporator – The stage evaporator is a long cylindrical vessel which has three stages, separated by two plates. Demister pads are provided at the top of the evaporator. Each stage has a mixing nozzle. There are two re-boilers for the second and first stage respectively. A gas pre-heater is also provided in which the recycle gas (85 % of the total gas) is pre-heated to 210 deg C from the main reactor effluent. The two re-boilers are heated by hot oil through tubes to a temperature of 250 deg C. Recycle gas mixed with feed is passed through the shell side. Downcomers are placed so that the liquid in the third stage enters the second and from second to first. Pressure inside the stage evaporator is around 2 mega-pascals.
Stage impeller – It is a component within a multi-stage pump system, where multiple impellers are arranged in series to improve pressure head capability and flow capacity, with configurations such as back-to-back being common for two-stage designs.
Staggered intermittent weld – It is an intermittent weld on both sides of a joint in which the weld increments on one side are alternated with respect to those on the other side.
Staggered-tooth cutters – These are milling cutters with alternate flutes of oppositely directed helixes.
Staging – In the context of fuel combustion, staging refers to a technique where the combustion process is divided into distinct stages, often with varying air or fuel ratios, to optimize efficiency and reduce emissions. This can involve staging air (introducing air at different points in the combustion chamber) or staging fuel (injecting fuel in multiple stages). In composites, staging is heating a premixed resin system, such as in a prepreg, until the chemical reaction (curing) starts, but stopping the reaction before the gel point is reached. Staging is frequently used to reduce resin flow in subsequent press moulding operations.
Stagnant zone – It is also known as a dead zone. It is an area where fluid flow is extremely slow or non-existent, leading to prolonged residence times for substances within it and impacting overall flow dynamics. These zones can occur in different contexts, such as in reactor vessels and porous media, and are detrimental since they can cause overheating, fuel damage, or poor mass transfer and transport. Another common type of stagnant zone is an oceanic dead zone, a water body with depleted dissolved oxygen levels which cannot sustain stagnant majority of the aquatic life.
Stagnation – It is the condition of being free from movement or lacking circulation. It refers to a period of decline or lack of progress in an organization or its performance. It can manifest in various ways, including slow or flat growth in key performance indicators (KPIs), lack of innovation, decreased employee engagement, and a failure to adapt to changing market conditions.
Stain – On an enameled surface, it is an iridescent spot caused by the action of fruit juice or chemicals.
Stain, heat treat – It is a discolouration because of the non-uniform oxidation of the metal surface during heat treatment.
Stain, oil – It is surface discolouration which can vary from dark brown to white and is produced during thermal treatment by incomplete evaporation and / or oxidation of lubricants on the surface.
Stain, saw lubricant – It is a yellow to brown area of surface discolouration at the ends of the extruded length. It is the residue of certain types of saw lubricants if they are not removed from the metal prior to the thermal treatment.
Stain, water – It is the superficial oxidation of the surface with a water film, in the absence of circulating air, held between closely adjacent metal surfaces.
Staining – It is precipitation etching which causes contrast by distinctive staining of micro-constituents. Different interference colours originate from surface layers of varying thickness. It is also known as colour etching.
Stainless steel –Stainless steels are characterized by corrosion resistance, aesthetic appeal, heat resistance, low life cycle cost, full recyclability, biological neutrality, ease of fabrication, cleanability and good strength to weight ratio. The selection of stainless steels is based on corrosion resistance, fabrication characteristics, availability, mechanical properties in specific temperature ranges, and product cost. However, corrosion resistance and mechanical properties are normally the most important factors in selecting a grade for a given application. Stainless steels are iron base alloys containing at least 10.5 % chromium. Few stainless steels contain higher than 30 % chromium or less than 50 % iron. These steels have chromium as the main alloying element and are valued for high corrosion resistance. These steels achieve their stainless characteristics through the formation of an invisible, self-healing, and adherent chromium rich oxide surface film. This oxide forms and heals itself in the presence of oxygen. Other elements added to improve particular characteristics include nickel, molybdenum, copper, titanium, aluminum, silicon, niobium, nitrogen, sulphur, and selenium. Carbon is normally present in quantities ranging from less than 0.03 % to over 1 % in certain martensitic grades. Stainless steels are normally divided into five groups namely (i) austenitic stainless steels, (ii) martensitic stainless steels, (iii) ferritic stainless steels, (iv) duplex (ferritic-austenitic) stainless steels, and (v) precipitation-hardening stainless steels. In each of the three original groups of stainless steels which are austenitic, martensitic, and ferritic, there is one composition which represents the basic, general-purpose steel. All other compositions derive from this basic steel, with specific variations in composition being made to impart very specific properties.
Stainless steel castings – These are parts produced by pouring molten stainless steel into a mould which has the desired shape. This process creates a solid, complex-shaped stainless-steel component with very good durability and corrosion resistance.
Stainless steel conveyor – It is a cutting-edge conveyor system meticulously fashioned from components of stainless steel, lauded for its unparalleled resistance to corrosion and exemplary durability. Stringent and unwavering maintenance practices are pivotal to repel corrosion, uphold hygiene standards, and elongate the operational life of these stainless-steel conveyors.
Stainless steel electrodes – These are commonly used electrode for welding purposes, especially in very high-temperature applications. These are made up of different qualities of stainless steels and provide good creep resistance when compared to other categories. Applied on a wide range of metals, these electrodes are one of the best options for welding differing materials e.g., stainless steel to mild and low alloy steels, joining metals with varying and unknown compositions, rough steels, etc.
Stainless steel reinforcement bars – These are also known as stainless steel rebars. These are steel bars used to reinforce concrete structures which are made of stainless steel instead of carbon steel. They are chosen for their excellent corrosion resistance, particularly in harsh environments where carbon steel might fail. These bars are typically ribbed or deformed to enhance the bond with concrete.
Stainless steel scrap – Stainless steel scrap consists of clean 18-8 type (300 series) stainless steel clips and solids containing a minimum of 16 % chromium, 7 % nickel, a maximum of 0.5 % phosphorous, and 0.03 % sulphur and is otherwise free of harmful contaminants. Typical scrap comes from the manufacture of sinks, tanks, and pipes, etc.
Stainless steel turnings – Stainless steel turnings consist of clean 18-8 type (300 series) stainless steel turnings containing a minimum of 16 % chromium, and 7 % nickel, and are free of non-ferrous metals, non-metallics, excessive iron, oil and other contaminants.
Stainless steel wire – It is a thin strand of stainless steel, an iron-based alloy containing at least 10.5 % chromium which forms a protective, rust-resistant layer on the surface. This material is prized for its strength, corrosion resistance, and durability, making it widely applicable in industries like construction, electronics, and manufacturing, where it is used for different components, devices, and structural elements.
Stakeholder management – It is the process of managing the expectation of the different groups of stakeholders. It is essentially stakeholder relationship management as it is the relationship and not the actual stakeholder groups that are managed. It is a critical component for the successful delivery of the products, programs or activities of the organization. Stakeholder management is also important because it helps identify positive existing relationships with stakeholders. These relationships can be converted to coalitions and partnerships, which go on to build trust and encourage collaboration among the stakeholders. Effective stakeholder management creates positive relationships with stakeholders through the appropriate management of their expectations and agreed objectives. It is a process and control that must be planned and guided by principles.
Stakeholders – Stakeholders refer to those people and groups who have a stake in some aspect of the organizational products, operations, markets, industry, or outcomes. Stake is an interest or a share in an undertaking and can be categorized as legal or moral. The stakeholders of an organization are the individuals, groups, or other organizations that are affected by and also affect the decisions and actions of the organization. Depending on the specific organization, stakeholders can include governmental agencies, statutory bodies, social activist groups, self-regulatory organizations, employees, shareholders, customers, suppliers, distributors, media and even the community in which the organization is located among many others. Stakeholders can be categorized into two groups namely (i) primary stakeholders, and (ii) secondary stakeholders. Primary stakeholders have direct stake in the organization and its success. They are fundamental to its operations and survival. These stakeholders include shareholders and investors, employees, customers, suppliers, and public stakeholders, such as government and the community. Secondary stakeholders influence and / or are affected by the organization but are neither engaged in transactions with the organization nor essential for its survival. These stakeholders are those that have a public or special interest stake in the organization. Stakeholders can also be categorized into two different groups namely (i) internal stakeholders, and (ii) external stakeholders. Internal stakeholders are those people who are closest to the organization and have the strongest or most direct claim on the organizational resources such as shareholders, management, and employees etc. External stakeholders are those people who neither own the organization (such as shareholders) and nor are employed by it, but they do have some interest in it or its activities. Customers, suppliers, the government, statutory bodies, trade and other unions, local communities, special interest groups, and the general public are some of the external stakeholders.
Staking – It is the fastening of two parts together permanently by recessing one part within the other and then causing plastic flow at the joint.
Stalked ciliates – These are a type of protozoan, specifically a ciliate, characterized by having a stalk-like structure that attaches them to a substrate, often floc or sludge in waste-water treatment systems. They are identified by their inverted bell-shaped head, also called a zooid, which is positioned at the top of the stalk. These ciliates use cilia (small hair-like structures) around their oral region (mouth) to create a water vortex, which helps them capture bacteria for feeding.
Stamp charging of coal – This is a technique of charge preparation for coke oven battery. It consists in preparing a cake with the coal blend in a metallic box, then charging it in the coke oven. The higher charge density implies better coke quality when compared with conventional charging. So, depending on the situation, either better coke quality can be achieved, or weakly coking coals can be included in the blend. Stamping of coals increases the bulk density of charge by 30 % to 35 % to around 1,150 kilograms per cubic meter. Crushing of coals to more than 90 % below -3 millimeters size and 40 % to 50 % below – 0.5 millimeters size is needed for a stable cake. With stamp charging, low rank, weakly coking, and high volatile coals can be used to the extent of around 20 %, but since the coal charge is compacted to high bulk density there can be problem of increased wall pressures. In order to ensure that the refractory oven walls are not damaged, the coal blend used is to be carefully chosen by optimum balancing between high and low volatiles coals.
Stamping – It is the general term used to denote all sheet metal press-working. It includes blanking, shearing, hot or cold forming, drawing, bending, or coining.
Stamping process – It is also known as pressing. It involves forming flat sheet metal into desired shapes and geometries using a punch and die under controlled force and velocity. This process is a fundamental technique in metalworking which is used to create a variety of components like automotive parts, appliances, and more
Stand – It is a piece of rolling mill equipment containing one set of work rolls. In the normal sense, it forms one of the passes of a cold-rolling mill or hot-rolling mill.
Stand-alone conveyor – It is a self-sufficient conveyor system which functions independently without integration into a larger network. Regular checks become imperative to uphold the autonomy and unwavering reliability of the stand-alone conveyor, ensuring its seamless solo operation.
Stand-alone process – It is a procedure, task, or system which operates independently, performing its function without relying on external connections, dependencies, or other systems to operate or complete its tasks. It is self-contained, self-sufficient, and can function on its own, much like a one-person operation which manages all its aspects without outside assistance.
Stand-alone system – It is a self-contained system, device, or programme which can function independently without needing external connections or dependencies on other systems, networks, or hardware to perform its primary function. Key characteristics include self-sufficiency, isolation, and the ability to operate on its own.
Standard – It is a recognized set of guidelines or specifications, developed through consensus by experts, which defines how to do something in a consistent and universally accepted way. The standards cover a wide range of areas, including quality, safety, environmental management, and more. They provide a framework for organizations to improve their processes, products, and services, ultimately leading to better quality, efficiency, and customer satisfaction. In case of inspection and testing, the testing of accuracy and precision of measuring device is made through a hierarchical system where each measuring device is compared against an external reference known as a ‘standard’. Each ‘standard’ is then tested against a higher level (more accurate and precise) ‘standard’, which is compared against an even higher ‘standard’, and so on.
Standard addition – It is a method in which small increments of a substance under measurement are added to a sample under test to establish a response function or, by extrapolation, to determine the quantity of a constituent originally present in the sample.
Standard air – It is a hypothetical, dry air at specific reference conditions for different engineering applications, frequently defined at sea level with specific pressure, temperature, and density. It is the dry air at 21.1 deg C temperature, 101.3 kilopascals of pressure, and a density of 1.204 kilograms per cubic metre. This allows for consistent measurement and comparison of air properties and airflow rates across different conditions.
Standard atmospheric conditions – These conditions define a reference set of pressure, temperature, and other atmospheric properties at a given altitude, used for calculations. The International Standard Atmosphere (ISA), a widely used model, sets a mean sea-level temperature of 15 deg C, pressure of 101,325 pascals, and relative humidity (60 %) with properties changing at set rates with increasing altitude.
Standard atmospheric pressure – It is the pressure exerted by the weight of air at sea level, typically approximated to 101.3 kilopascal, although it can vary because of weather conditions and altitude.
Standard Brayton cycle – It is an ideal thermodynamic cycle which consists of two isobaric processes and two isentropic processes, typically utilized in gas turbine systems to achieve maximum adiabatic thermal efficiency by approximating the isothermal compression and expansion of the Carnot cycle.
Standard depth of penetration – It refers to the depth at which a specific type of electro-magnetic radiation or a physical phenomenon (like eddy currents) has its intensity reduced to around 36.8 % (or 1/e) of its original value at the surface. This depth is a critical parameter in several applications, including non-destructive testing, electro-magnetic wave propagation, and materials science.
Standard deviation – It is a measure of how spread out or dispersed a set of data is around its mean (average). It is essentially the average distance of each data point from the mean. A lower standard deviation indicates that data points are clustered closely around the mean, while a higher standard deviation suggests they are more dispersed.
Standard electrode potential – It is an equilibrium electrode potential for an electrode in contact with an electrolyte in which all of the components of a specified chemical reaction are in their standard states. The standard for state for an ionic constituent is unit ion activity. It is the reversible for an electrode process when all products and reactions are at unit activity on a scale in which the potential for the standard hydrogen half-cell is zero.
Standard error – It is the standard deviation of the sampling distribution of a statistic. The positive square root of the variance of the sampling distribution of a statistic. The standard error is a measure of precision. It is a key component of statistical inference. The standard error of an estimator is a measure of how close it is likely to be, to the parameter it is estimating.
Standard error of estimate – It is the standard deviation of the observed values about a regression line.
Standard error of the ‘mean’ (SEM) – It is the standard deviation of the means of several samples drawn at random from a large population. It is an estimate of the quantity by which an obtained mean can be expected to differ by chance from the true mean. It is an indication of how well the mean of a sample estimates the mean of a population
Standard flow – For those rotary control valves having a separate seal ring or flow ring, it is the flow direction in which fluid enters the valve body through the pipeline adjacent to the seal ring and exits from the side opposite the seal ring. It is sometimes called forward flow or flow into the face of the closure member.
Standard flue gas – It is the gas weighing 1.25 kilogram per cubic metre at sea level (101 kilopascals pressure) and 20 deg C.
Standard Gibbs free energy – It is the change in Gibbs free energy which occurs when a process is carried out under standard conditions, where substances are in their most stable forms at a specified temperature and 1 atm (or 1 M for solutions). It represents the maximum quantity of non-mechanical work that can be done by a system at constant temperature and pressure, and its value indicates whether a reaction is spontaneous, non-spontaneous, or at equilibrium.
Standard gold – It is a gold alloy containing 10 % copper. At one time it was used for legal coinage in several countries.
Standard grade – It refers to a material which meets specific quality and performance requirements defined by a recognized organization or standard. It is a way of classifying materials based on their chemical composition, mechanical properties, and other characteristics, ensuring consistency and predictability in their use.
Standard grain-size micrograph – It is a micrograph taken of a known grain size at a known magnification which is used to determine grain size by direct comparison with another micrograph or with the image of a sample.
Standard hydrogen electrode (SHE) – It is a redox electrode which forms the basis of the thermo-dynamic scale of oxidation-reduction potentials. Its absolute electrode potential is estimated to be 4.44 +/- 0.02 volts at 25 deg C, but to form a basis for comparison with all other electro-chemical reactions, hydrogen’s standard electrode potential (E0) is declared to be zero volts at any temperature. Potentials of all other electrodes are compared with that of the standard hydrogen electrode at the same temperature.
Standard illumination conditions – These are specific, controlled lighting environments defined by a theoretical light source with a defined spectral power distribution, used to ensure consistent and comparable results in tasks like color measurement and scientific testing. By establishing these fixed reference points, they address inconsistencies in natural and artificial light which can alter colour perception and other measurements. For example, the AM 1.5G spectrum is a standard illumination condition for testing solar cells, while CIE standard illuminants are used for color evaluation.
Standardization – It is defined as an activity of establishing, with regard to actual or potential problems, provisions for common and repeated use, aimed at the achievement of the optimum degree of order in a given context. Important benefits of standardization are improvement of the suitability of products (including services) and processes for their intended purposes, prevention of barriers to trade and facilitation of technological co-operation. Standardization can be described as the ‘activity of establishing a standard’. Standardization in several standards is subject to specific rules. Standardization means creating uniform business processes across various divisions or locations. The expected results are processes which consistently meet their cost and performance objectives using a well-defined practice. Standardization, hence, reduces the risk of failure. The major aims of the process of standardization are (i) fitness for purpose, (ii) interchangeability, (iii) variety reduction, (iv) securing compatibility and interface consistency, (v) health and safety of consumers, (vi) environmental protection, (vii) improved utilization of resources, (viii) product quality standards, (ix) enhanced communication and understanding, (x) facilitating communication and learning, (xi) transfer of technology, (xii) improvement in the efficiency, (xiii) streamlining of procedures, (xiv) facilitating competitive environment, and (xv) removal of trade barriers.
Standardization and rationalization – It is a combined design and business approach which specifically targets reduction in the number of parts organization-wide. Standardization refers to the reduction in number of parts used in current and former designs. Rationalization is the identification of the fewest number of parts needed for use in future designs.
Standardization process – It refers to the systematic organization and uniformity of work practices and documentation within management systems, aiming to meet stakeholder expectations efficiently while minimizing costs, variability, and resource waste. It includes establishing procedures which dictate how tasks are to be performed and ensures consistent practices across the organization.
Standard leak – It is a device which permits a tracer gas to be introduced into a leak detector or leak testing system at a known rate to facilitate calibration of the leak detector.
Standard leakage rate – It is the rate of flow of atmospheric air under conditions in which the inlet pressure is 0.1 mega-pascal (MPa), outlet pressure is less than 1 kilopascal, temperature is 25 +/- 5 deg C and dew point is less than -25 deg C.
Standard module – It is a product manufactured in quantity for use in a number of other products. Examples are motors, clutches, switches, pumps, etc. Standard modules are normally offered for sale through the catalogs of their manufacturers.
Standard modulus – It refers to the modulus of elasticity. It also known as Young’s modulus, of a material. It is a measure of how stiff a material is, indicating its resistance to deformation under stress. Specifically, it refers to the slope of the stress-strain curve in the elastic region, which is the area where the material returns to its original shape after the stress is removed.
Standard normal distribution – It is also known as the z-distribution. It is a special case of the normal (bell-shaped) distribution with a mean (mu) of 0 and a standard deviation (sigma) of 1. It is a fundamental concept in statistics, allowing any normal distribution to be converted into a standard form using z-scores, which indicate how many standard deviations a data point is from the mean.
Standard normal transformation – Fortunately, the analyst can transform any normal distributed variable into a standard normal distributed variable by making use of a simple transformation.
Standard operating procedure (SOP) – It is defined as the established or prescribed methods to be followed routinely for the performance of designated operations or in designated situations. It is a document consisting of step-by-step information on how to execute a task. It is a set of written instructions that document a routine or repetitive activity which is followed by an organization. In a manufacturing organization, a standard operating procedure is the step-by-step production line procedures used to run a process for producing a product as well to train employees. The existence of documented procedures improves the value of an organization. It shows that the organization is a professional organization which is process driven, rather than top management driven.
Standard part – A standard part, like a screw or spring, has a generic function and is manufactured in quantity without the intention of being used in a particular product.
Standard pattern – It is a pattern of high-grade material and workmanship in daily use or at frequent intervals. A pattern used as a master to make or check production patterns.
Standard penetration test (SPT) – It is a common in-situ geotechnical test which determines the engineering properties of subsurface soils by driving a split-spoon sampler into the ground at the bottom of a borehole. The number of blows needed to drive the sampler a specific distance, known as the N-value, indicates the soil’s relative density and is used to estimate its shear strength and bearing capacity, which are vital for designing foundations and other structures.
Standard pipe – It is standard weight, extra strong, and double extra strong welded or seamless pipe of ordinary finish and dimensional tolerances, produced in sizes up to 650 millimeters nominal diameter, inclusive. This pipe is used for fluid conveyance and some structural purposes.
Standard pipe size – It is typically defined by two main components namely nominal pipe size (NPS) and Schedule. Nominal pipe size, a dimensionless designation, is a pipe standard which refers to the pipe’s approximate outside diameter, while the schedule indicates the wall thickness, influencing the pipe’s pressure rating and strength.
Standard power demand – It refers to the rate at which electrical energy is consumed, typically measured in kilowatts (kW), representing the quantity of power required to operate devices or systems at a given time. In simpler terms, it is how fast electricity is being consumed, rather than the total quantity consumed over a period.
Standard property – It is the property which is determined as part of the routine inspection and test requirements.
Standard reference material – It is a reference material, the composition or properties of which are certified by a recognized standardizing agency or group. Standard reference materials are discrete quantities of substances or minor artifacts which have been certified as to their composition, purity, concentration, or some other characteristic useful in the calibration of the measurement devices and the measurement processes normally used in the process control of those substances. Standard reference materials are the essential calibration standards in stoichiometry (the metrology of chemistry). Standard reference materials range from ores to pure metals and alloys. They also include many types of gases and gas mixtures as well as and many biochemical substances and organic compounds. Among the artifact devices available are optical filters with precise characteristics and standard lamps with known emission characteristics.
Standards – These are documents, established by consensus and approved by a recognized body, that provides, for common and repeated use, rules, guidelines or characteristics for activities or their results, aimed at the achievement of the optimum degree of order in a given context. Standards aim at achieving the optimum degree of order in a given context. The process of formulating, issuing, and implementing standards is called standardization. Standards aim at achieving the optimum degree of order in a given context.
Standard samples – It is a sample of know composition used to calibrate an instrument or method of analysis.
Standard scores – These are scores expressed in terms of standard deviations away from the mean.
Standard shapes – Refractory objects are manufactured in standard shapes and special shapes. Standard shapes have dimensions which conform to conventions used by refractory manufacturers and are normally applicable to kilns or furnaces of the same types. Standard shapes are normally bricks which have a standard dimension. Standard shapes are refractory units stocked by manufacturers or made from stock moulds.
Standards laboratory – It is a work space, provided with equipment and standards, a properly controlled environment, and trained personnel, established for the purpose of maintaining traceability of standards and measuring equipment used by the organization it supports. Standards laboratories typically perform fewer, more specialized and higher accuracy measurements than the calibration laboratories.
Standard solution – It is also called titrant or titrator. It is a solution containing an accurately known concentration. Standard solutions are normally prepared by dissolving a solute of known mass into a solvent to a precise volume, or by diluting a solution of known concentration with more solvent. A standard solution ideally has a high degree of purity and is stable enough that the concentration can be accurately measured after a long shelf time. Making a standard solution needs high attention to detail to avoid introducing any risk of contamination which can diminish the accuracy of the concentration. For this reason, glassware with a high degree of precision such as a volumetric flask, volumetric pipette, micro-pipettes, and automatic pipettes are used in the preparation steps. The solvent used is also to be pure and readily able to dissolve the solute into a homogenous solution.
Standard temperature and pressure (STP) – These are defined as a temperature of 0-drg C (273.15 K) and a pressure of 1 atmosphere (101.325 kPa), though definitions can vary by context. These reference conditions are used to ensure consistent and comparable measurements of gases and other substances. For instance, the density or molar volume of a gas is frequently reported at standard temperature and pressure to allow for easier comparison and calculations.
Standard test method – It is a documented procedure outlining the specific steps and conditions for conducting a test to measure a property or characteristic of a material or product, ensuring that the test results are consistent, comparable, and repeatable across different laboratories and over time. These methods are developed by experts in the relevant field, and standard organizations, to provide a reliable and objective basis for assessing product quality, performance, and safety.
Standard time – It is the time needed to perform a step in a manufacturing or assembly operation of a product. These times, normally in seconds, are obtained from empirical observations.
Standard title block – It is a rectangular area in engineering drawings, normally in the bottom right corner, which contains vital information about the drawing. It acts as a reference point, providing details of the drawing. The title blocks are locally standardized but are to be designed in such a way that it can be easily understood. The information normally included in any standard title block is normally (i) name of the organization along with its logo, (ii) name of the object, (iii) number of the drawing (particularly useful for reference where more than one drawing are concerned, typically in assembly drawings), (iv) revision number, (v) format of the paper used (paper size), (vi) scale used, (vii) dimensioning unit (normally millimetres), (viii) symbol for the method of projection used, (ix) date when the drawing has been finished, (x) name of the person who has prepared the drawing, , (xi) name of the person who has checked the drawing, and (xii) remarks.
Standard voltage – It is the voltage of the electric power which is normally distributed to the consumers. It is the value of the voltage of the electric power for which the holding electromagnet coil has been made.
Standby mode – It is an operational phase wherein a conveyor system temporarily remains inactive, poised to swiftly resume operation when the need arises. Routine checks are vital to guarantee the seamless transition between standby and active modes, contributing to operational efficiency.
Standing wave ratio – It is a measure of impedance mismatch for transmission lines in microwave engineering. It is the ratio of peak amplitude of a standing wave to its minimum.
Stand-off distance – It is the distance between a nozzle and the work-piece.
Standpipe – In coke ovens, It is a vertical pipe which connects a coking chamber to a gas collecting main. It is used to withdraw gases produced during the coking process. Specifically, stand-pipes are part of the gas offtake system, inter-connecting the individual coke ovens to a common collecting main. They facilitate the removal of these gases, which can be further processed or used as fuel.
Standpipe pressure (SPP) – It is the desired pressure in a vertical pipe used to supply water to fire hoses or to maintain a desired head pressure in a water supply system.
Stand stretch – It represents the elastic behaviour of the mechanical structure of the stand when a compressing force is generated by the main hydraulic cylinder (i.e., the hydraulic gap control cylinder). This characteristic is to be known in advance for implementing the automatic gauge control in hot strip mill and for this reason a suitable control sequence is implemented and executed off-line, that is, before rolling, known as the ‘stretch acquisition sequence (SAS). The SAS is obtained by putting the work rolls in contact and linearly modifying the position reference for the hydraulic gap control from a minimum value to a maximum value. For each position reference, the force measured by the load cells (or by the hydraulic gap control hydraulic force measurement) is recorded in order to build a stretch characteristic. The records are, in general, performed twice. The first records are made with increasing hydraulic gap control position references (up readings) and the second records are made with decreasing hydraulic gap control position references (down readings).
Stand support sintering – A new sintering technique called ‘stand support sintering’, to support the sinter cake with steel stands (bars or plates) attached to pallets has been developed in Japan. This technique improves shrinkage, porosity, and reducibility rates. Because of the stand support system, the productivity of sinter machine increases considerably and the machine runs more stably. In the stand support sintering method, the load of sinter cake in the upper portion of the sinter mix bed is supported by steel stands during the sintering process. The load of the sinter cake on the combustion melting zone below it makes the sinter mix bed shrink (bed compaction), and thus significantly deteriorates the permeability of the bed. The support stands installed inside the sintering pallets begin to support the load of the sinter cake above at the time when the sinter mix bed portion around the tops of the stands begins to solidify after heating and melting. The sintering process of the lower portion of the bed proceeds thereafter under a reduced load, and a permeation network develops well in the portion to improve permeability.
Staple fibre – It consists of short lengths of glass fibre, normally U-shaped, which intertwine and are used, in particular, to create insulation materials. Staple fibres are fibres of spinnable length manufactured directly or by cutting continuous filaments to short lengths (normally 12.5 millimeters to 50 millimeters long and 1 denier to 5 denier.
Starch adhesive – It is a natural, sustainable adhesive made from plant-based starches. It functions by creating strong molecular bonds between surfaces, forming a stable suspension in water which can be cooked and applied to bond different substrates, particularly paper-based materials for packaging.
Starch and dextrin – These are poly-saccharides used as adhesives, with starch being an ancient adhesive and dextrins offering improved properties such as faster tack development and increased production rates in several applications, including laminating and sealing.
Star connection – It is also called ‘Y’ connection. It refers to a method of wiring a three-phase electrical system where the windings of a load (like a motor) or the secondary windings of a transformer are connected at a common point, creating a ‘star’ or ‘Y’ shape. This common point is frequently referred to as the neutral point, which can be grounded to provide a return path for unbalanced currents.
Star cracks – These cracks are very fine and caused by fragile nature of the strand at high temperatures. They are visible only on scale free surface. The surface is normally ground locally to remove the defect. Intense local cooling and presence of copper at the austenitic grain boundary cause star cracks. To avoid the star cracks in the cast product it is necessary to have (i) correct correlation between the spray flow and the casting speed, (ii) a uniform layer of melted casting powder between the strand and the mould, and (iii) adequate secondary cooling of the strand for avoiding increase of the thermal stress.
Star dusting – It is an extremely fine form of roughness on the surface of a metal deposit.
Stark effect – It is a shift in the energy of spectral lines because of an electrical field which is either externally applied or is an internal field caused by the presence of neighboring ions or atoms in a gas, solid, or liquid.
Star marks – It is a defect which sometimes occurs in sheet steel or iron porcelain enamel cover coats where the dried ware is set down too hard on the firing fixture points and the enamel coating is fractured.
Star-mesh transform – It is a mathematical technique used in circuit analysis.
Stars – In porcelain enamel, it is a defect in the fired surface which appears as a series of small hairlines radiating from a common centre. It is similar to star marks. It is typical of porcelain enamel powder systems.
Starter motor – It is a powerful electric motor used in internal combustion engines to provide the initial torque needed to turn the engine’s crankshaft and initiate the combustion cycle. It engages with the engine’s flywheel through a small gear (pinion), which meshes with a larger ring gear. This action cranks the engine, allowing it to draw in a fuel-air mixture and start running on its own.
Starting current – It is also known as inrush current or locked rotor current. It is the high surge of electrical current which flows when a motor or other inductive load is first energized. It is the initial, large burst of current needed to overcome inertia and build up the magnetic field necessary for operation. This current is typically much higher than the normal running current of the device.
Starting sheet – It is a thin sheet of metal which is used as the cathode in electrolyte refining.
Starting structure defects– These defects include segregation, piping, and porosity of solidification structure.
Starting tension – It is the tension necessary to accelerate a belt from rest to normal operating speed.
Starting torque – It is the torque which is needed for initiating rotary motion.
Start/stop shears – These shears are very similar to clutch and brake shears, but in this case the motor and the shear gear box are permanently connected. This kind of shear needs very accurate blade position control to assure high precision and reliability. In the present applications of these shears, it is usually not necessary to replace the entire system, merely to apply a new motion control system to the existing drive.
Start-up sequence – It is the meticulously preordained series of actions executed when initiating the conveyor system. Consistent checks and vigilant monitoring are essential to orchestrate a flawlessly smooth and safe start-up sequence, averting potential issues like overload or misalignment.
Starvation – It means non-uniform coating application which results in the absence of coating in certain areas.
Starved area – It is an area in a plastic part which has an insufficient quantity of resin to wet out the reinforcement completely. This condition can be because of (i) improper wetting, impregnation, or resin flow, (ii) excessive moulding pressure, or (iii) improper bleeder cloth thickness.
Starved joint – It is an adhesive joint which has been deprived of the proper film thickness of adhesive because of insufficient adhesive spreading or to the application of excessive pressure during the lamination process.
Starved lubrication – It is a condition where insufficient lubricant is supplied to a machine’s friction interface, leading to a reduced lubricant film thickness which can hinder effective separation of contacting surfaces, increase wear, and potentially cause premature equipment failure. Unlike fully flooded lubrication, where enough lubricant ensures a stable film, starvation occurs when the availability of lubricant at the contact point is limited, preventing the generation of sufficient pressure and resulting in thinner films than occur under ideal conditions.
Statement of concern – It is a formal document expressing worry or anxiety about a specific situation, frequently with the intention of prompting change or improvement. It can be used in various contexts, including addressing workplace issues, expressing disagreement with a proposal, or highlighting potential problems with an action.
Statement of conformity – It is a declaration that a product, service, or process meets specific requirements, standards, or specifications. It can be a simple ‘pass / fail’ or ‘in specification’ evaluation provided by a testing laboratory, or it can be a formal document like a Declaration of Conformity (DoC) or Certificate of Conformity (CoC) issued by a manufacturer or a third party, confirming legal and technical compliance.
State observer – In control theory, it is that which discovers and reports the internal state of a controlled system.
State of the art – It means something which is of the highest current level of development or advancement in a particular field, using the most modern techniques and technology. It implies that the item or technology is the best and most up-to-date available at the present time.
State-of-the-art technology – It refers to the most advanced, modern, and cutting-edge technology available in a specific field or industry presently. It represents the highest level of development, frequently incorporating the most up-to-date techniques, methods, and features, making it the best or most effective option available presently.
State of cure – It is the cure condition of a vulcanizate relative to that at which optimum physical properties are obtained.
State of matter – It is one of the distinct forms in which matter can exist. Four states of matter are observable in everyday life. These are solid, liquid, gas, and plasma. Several intermediate states are known to exist, such as liquid crystal, and some states only exist under extreme conditions, such as Bose–Einstein condensates and Fermionic condensates (in extreme cold), neutron-degenerate matter (in extreme density), and quark–gluon plasma (at extremely high energy). Historically, the distinction is based on qualitative differences in properties. Matter in the solid state maintains a fixed volume (assuming no change in temperature or air pressure) and shape, with component particles (atoms, molecules or ions) close together and fixed into place. Matter in the liquid state maintains a fixed volume (assuming no change in temperature or air pressure), but has a variable shape that adapts to fit its container. Its particles are still close together but move freely. Matter in the gaseous state has both variable volume and shape, adapting both to fit its container. Its particles are neither close together nor fixed in place. Matter in the plasma state has variable volume and shape, and contains neutral atoms as well as a significant number of ions and electrons, both of which can move around freely.
State of strain – It is a complete description of the deformation within a homogeneously deformed volume or at a point. The description needs, in general, the knowledge of the independent components of strain.
State of stress – It is a complete description of the stresses within a homogeneously stressed volume or at a point. The description needs, in general, the knowledge of the independent components of stress.
State space representation – It is a mathematical technique to represent the internal state of a controlled system as a vector in a Euclidean space.
State transition – It is the movement of a system from one distinct condition or state to another in response to a specific event or input. It defines how a system’s configuration or status changes over time, frequently represented in a state-transition diagram as a directed arc connecting two states, indicating the trigger and the resulting change.
State variable – It is a variable used to describe the present ‘state’ or condition of a system. These variables are necessary for understanding a system’s behaviour since their values, combined with the inputs, determine the system’s future behaviour. Examples include temperature and pressure for a thermodynamic system or current and voltage for an electrical system.
Statically indeterminate – Bottom of Form A A structure is statically indeterminate when the equilibrium equations, force and moment equilibrium conditions, are insufficient for determining the internal forces and reactions on that structure.
Static characteristics – These characteristics of an instrument are those characteristics which do not vary with time and are normally considered to check if the given instrument is fit to be used for measurement. The static characteristics are checked by the process of calibration. These characteristics are normally considered for those instruments which are used to measure a stable process condition.
Static coefficient of friction – It is the coefficient of friction corresponding to the maximum friction force which is to be overcome to initiate macroscopic motion between two bodies.
Static conductivity – It is the inherent capacity of conveyor components to disperse static electricity and thwart the accumulation of static charges. Periodic assessments are critical to sustain optimal conductivity, hence preventing static-related challenges within the conveyor system.
Static dielectric constant – It is a measure of a material’s ability to store electrostatic energy in response to a static or very low-frequency electric field. It represents the ratio of the static electrical field in a vacuum to the static electrical field within the material when an external electric field is applied. A higher static dielectric constant indicates a higher ability of the material’s atomic or molecular structure to polarize and reduce the internal electric field.
Static electrode potential – It is the electrode potential measured when no net current is flowing between the electrode and the electrolyte.
Static end-point carbon prediction – It mainly relies on the mathematical model established based on mass and heat balance, which can calculate the end-point carbon content in the liquid steel based on the initial charge parameters (such as charged hot metal and scrap, and composition and temperature of hot metal). The key point of static end-point carbon prediction is the reasonable establishment of mathematical mode and acquisition of initial amount data. Compared with the randomness and uncertainty of end-point carbon prediction based on the experience and skill of the operator, the static end-point carbon prediction can perform a quantitative calculation of blown oxygen and end-point carbon content, which improves the prediction accuracy of the end point carbon. The normally used mathematical models for static end-point carbon prediction mainly include theoretical model, and statistical model.
Static equivalent load (Po) – In rolling-element bearings, it is the static load which, if applied, gives the same life as that which the bearing attains under actual conditions of load and rotation.
Static error – In a measuring instrument, it is the numerical difference between the true value of a quantity and its value as obtained by measurement, i.e., repeated measurement of the same quantity gives different indications. Static error occurs because of the shortcomings of, the instrument, such as defective or worn parts, or ageing or effects of the environment on the instrument. Static error is caused by limitations of the measuring device or the physical laws governing its behaviour. This error is sometimes referred to as bias. Static error influences all measurements of a quantity alike. Static errors are categorized as (i) instrument errors, (ii) environment errors, and (iii) random errors.
Static fatigue – It is a term which is sometimes used to identify a form of hydrogen embrittlement in which a metal appears to fracture spontaneously under a steady stress less than the yield stress. There almost always is a delay between the application of stress (or exposure of the stressed metal to hydrogen) and the onset of cracking. It is more properly referred to as hydrogen-induced delayed cracking. In composites, static fatigue means failure of a part under continued static load. It is analogous to creep rupture failure in metals testing, but frequently the result of aging accelerated by stress.
Static friction – It is the resistance which is to be overcome to start a body sliding down a belt surface.
Static hot pressing – It is a process which combines compaction and sintering in a single step by applying both heat and pressure simultaneously. This technique is used to create fully dense materials with improved properties, including high density and fine-grained microstructures.
Static loading – It means stationary or very slow loading. Frequently, it is used in connection with routine tension testing of metal samples.
Static load rating (Co) – In rolling-element bearings, it is the static load which corresponds to a permanent deformation of rolling element and race at the most heavily stressed contact of 0.00001 of the rolling-element diameters.
Static load testing – It is an in-situ type of load testing which is used in geotechnical investigation to determine the bearing capacity of deep foundations prior to the construction of a building. It differs from the statnamic load test and dynamic load testing in that the pressure applied to the pile is slower. Static load testings are performed in order to measure a design’s axial tension or axial compression. It can also be used to measure its deflected shape under lateral load.
Static magnetic field – It is a magnetic field which remains constant over time, not changing in intensity or direction. These fields are generated by sources like permanent magnets or a steady flow of direct current (DC) electricity. Unlike time-varying electro-magnetic fields, static magnetic fields have a frequency of 0 hertz and exert a force on moving charged particles.
Static modulus – It is the ratio of stress to strain under static conditions. It is calculated from static stress-strain tests, in shear, compression, or tension. It is expressed in force per unit area.
Static modulus of elasticity of concrete -It is frequently referred to as the chord modulus or secant modulus, is a measure of its resistance to deformation under stress. It’s calculated as the slope of the line connecting the origin of a stress-strain curve to a point representing a specific stress level, typically 1/3rd of the ultimate stress. This value is used to estimate deformations in concrete structural members.
Static operating loads – These loads include the weight of gas or liquid in the equipment during normal operation and forces, such as the drive torque developed by some equipments at the connection between the drive mechanism and driven equipment. Static operating loads can also include forces caused by thermal growth of the equipment and connecting piping. Time varying (dynamic) loads generated by equipments during operation are covered under dynamic loads.
Static pole – It is a normally single free-standing steel pole which creates a shield to protect all of the equipment inside a sub-station from lightning. Static poles may or may not have overhead shield wires attached to improve protection.
Static pressure – It refers to the pressure exerted by a fluid when it is at rest. It is also known as hydrostatic pressure. It is the pressure because of the weight or force of gravity acting on the fluid particles. This pressure is the same in all directions when the fluid is stationary. It is the measure of potential energy of a fluid.
Statics – It is the branch of classical mechanics which is concerned with the analysis of force, and torque acting on a physical system that does not experience an acceleration, but rather is in equilibrium with its environment.
Static stress – It is a stress in which the force is constant or slowly increasing with time, for example, test to failure without shock.
Static synchronous compensator (STATCOM) – It is a high-speed, power electronic device which provides dynamic reactive power control for a power grid by absorbing or generating reactive power to maintain voltage stability. As a type of ‘flexible alternating current transmission system’ (FACTS) device, it connects to the grid in parallel (shunt-connected) and uses a voltage-sourced converter to provide fast, controllable compensation, unlike passive devices like capacitors and inductors.
Static torque – It is the twisting force exerted on an which does not produce an angular acceleration, meaning the object remains at rest or is held in a state of equilibrium. This occurs when a force is applied, but the resulting rotation is either prevented or so small that no movement happens, such as when pushing on a closed door or trying to turn a stubborn bolt with a wrench.
Static unbalance – It is the net force produced on the valve stem by the process fluid pressure acting on the closure member and stem with the fluid at rest and with stated pressure conditions.
Static VAR (volt ampere reactive) compensator – It is a system which adjusts reactive power flow without moving parts, such as an electronically controlled capacitor bank.
Static viscosity – It is the bulk property of a fluid, semifluid, or semisolid substance which causes it to resist flow
Station – It is an enlargement of a shaft made for the storage and handling of equipment and for driving drifts at that elevation.
Stationary beam – It is a beam of radiation which remains in a fixed position relative to the object, without any movement or displacement. I
Stationary phase – In chromatography, it is a particulate material packed into the column or a coating on the inner walls of the column. A sample compound in the stationary phase is separated from compounds moving through the column as a result of being in the mobile phase.
Stationary ropes – These ropes are stay ropes (spiral ropes, mostly full-locked) and have to carry tensile forces. These ropes are therefore mainly loaded by static and fluctuating tensile stresses. Ropes used for suspension are frequently called cable.
Stationary source – It is a fixed-site producer of pollution, mainly power plants and other facilities using industrial combustion processes.
Stationary wave – In wave physics, a stationary or standing wave is a wave formed by the superposition of two identical waves traveling in opposite directions, resulting in a wave pattern which appears to be fixed in place rather than propagating forward.
Statistic – It is a summary value calculated from a sample of observations.
Statistical control – It consists of statistically holding other explanatory variables constant when looking at the effect of a given predictor on a study end point. It is designed to mimic the kind of control achieved with random assignment to levels of the predictor. However, it is no substitute for random assignment, as it only controls for measured characteristics.
Statistical data – It refers to the numerical or quantitative information which is systematically collected, organized, and analyzed to understand and optimize processes, products, or systems. These data points represent measurements, counts, or observations of characteristics like component dimensions, manufacturing tolerances, or process control, forming the basis for applying statistical methods to identify patterns, test hypotheses, and make informed decisions to improve performance and reliability.
Statistical distribution – It is a function describing how frequently different values of a variable occur within a dataset, showing where data points concentrate and how they spread. It is an important tool for engineers to analyze data, make predictions, design reliable systems by understanding potential variations, and select appropriate statistical methods for different engineering problems.
Statistical independence – In probability theory, two events are said to be statistically independent if, and only if, the probability that they both occur equals the product of the probabilities which each one, individually occur, i.e., one event does not depend on another for its occurrence or non-occurrence.
Statistical inference – It is also called inductive statistics, statistical inference is a form of reasoning from sample data to population parameters, that is, any generalization, prediction, estimate, or decision based on a sample and made about the population. There are two schools of thought in statistical inference, classical or frequentist statistics for which RA Fisher is considered to be the founding father, and Bayesian inference, discovered by a man bearing the same name.
Statistical interaction (also known as stratification effects) – It is the situation in which the nature of the association between a predictor and a study end point is different for different levels of a third variable.
Statistical methods – Statistical methods are similar to a glass lens through which the analyst inspects phenomenon of interest. The underlying mechanisms present in the population represents reality, the sample represents a blurry snap shot of the population, and statistical methods represent a means of quantifying different aspects of the sample.
Statistical model – It is a set of one or more equations describing the process or processes which generated the scores on the study end point. It concerns the relation between input variables and output variables using statistical analysis of collected data without considering the chemical reaction mechanism in the liquid bath, which is depicted by the equation X = F (W, S, T, t, Z), where ‘F’ is a linear or nonlinear function, ‘W’ is the charged weight of hot metal and scrap,’ S’ are the target values of end-point composition in liquid steel, ‘T’ is the initial temperature of hot metal, ‘t’ is the oxygen blowing time, and ‘Z’ are other important influential factors (such as top lance height and oxygen pressure).
Statistical power – It is the capability of a test to detect a significant effect or how frequently a correct interpretation can be reached about the effect if it is possible to repeat the test several times.
Statistical process control (SPC) – It is a technique which is used to predict when a steelmaking function’s quality can deteriorate. By tightly monitoring the product’s variance from specifications, the operator can determine when to apply preventative maintenance to a machine before any low-quality (secondary) steel is produced. Though utilized in several formats, statistical process control is simply the use of statistical techniques such as control charts to analyze a process or its output and hence enable appropriate actions to be taken to achieve and maintain a state of statistical control. The use of statistical process control instead of traditional quality control methods such as inspection / sorting is beneficial in a number of ways. Statistical process control (i) decreases scrap, rework, and inspection costs by controlling the process, (ii) decreases operating costs by optimizing the frequency of tool adjustments and tool changes, (iii) maximizes productivity by identifying and eliminating the causes of out-of-control conditions, (iv) allows the establishment of a predictable and consistent level of quality, and (v) eliminates or reduces the need for receiving inspection by the purchaser because it produces a more reliable, trouble-free product, resulting in increased customer satisfaction.
Statistical quality control (SQC) – The practice of controlling product quality against the specifications using statistical tools is known as statistical quality control. Statistical quality control is to be viewed as a kit of techniques which can influence decisions to the functions of specification, production, or inspection. It is defined as the technique of applying statistical methods based on the theory of probability and sampling to establish quality standard and to maintain it in the most economical manner. It is an economic and effective system of maintaining and improving the quality of outputs throughout the whole operating process of specification, production, and inspection based on continuous testing with random samples. Quality control includes quality of product or service given to customer, leadership, commitment of the management, continuous improvement, fast response, actions based on facts, employee participation and a quality driven culture. Objective of statistical quality control is to control (i) the material reception, internal rejections, and clients claims, (ii) evaluations of the same, and (iii) corrective actions and their follow-up. These systems and methods guide all quality activities. The development and use of performance indicators is linked directly or indirectly to the customer requirements and satisfaction as well as to the management. The seven basic techniques used for statistical quality control are (i) check sheets, (ii) histograms, (iii) Pareto analysis, (iv) control chart, (v) cause and effect diagram, (vi) stratification, and (vii) scatter diagram.
Statistical reliability – It is the probability that a system or component perform sits intended function without failure for a specified time interval under given conditions, using statistical methods and data to predict and quantify this likelihood. It relies on probability theory and statistical analysis to describe and forecast failure phenomena, which are inherently variable, even among seemingly identical systems. Key statistical concepts like failure rates, mean-time-to-failure (MTTF), and survival functions are used to model system behaviour, assess confidence levels, and predict future failures based on historical data and component lifetimes.
Statistical risk – It is a quantification of a situation’s risk using statistical methods. These methods can be used to estimate a probability distribution for the outcome of a specific variable, or at least one or more key parameters of that distribution, and from that estimated distribution a risk function can be used to obtain a single non-negative number representing a particular conception of the risk of the situation.
Statistical significance – It is the condition in which the ‘p’ value for a statistical test is below the alpha level for the test, leading to rejection of the null hypothesis.
Statistical tolerance model – It is also known as statistical tolerancing. It is a method of applying geometric dimensioning and tolerancing (GD&T) which uses statistical principles and data to determine appropriate tolerance limits for each feature. It aims to understand and manage variation in manufacturing processes and their impact on the overall quality and function of a product.
Statistics – It is the discipline which concerns the collection, organization, analysis, interpretation, and presentation of data. In applying statistics to a scientific, industrial, or social problem, it is conventional to begin with a statistical population or a statistical model to be studied. Populations can be diverse groups of people or objects such as ‘all people living in a country’ or ‘every atom composing a crystal’. Statistics deals with every aspect of data, including the planning of data collection in terms of the design of surveys and experiments. Statistics are becoming important tools in the operation of production shops, providing numerical process analysis capabilities which far exceed the more traditional recording of simple failure rates.
Stator – It is the stationary component of an electric motor or generator. It consists of a laminated core and windings of insulated wire, which create a rotating magnetic field when alternating current is applied. The stator is the part that does not move, while the rotor is the rotating part.
Stator coil – It refers to an insulated winding of wire installed within the stationary part (stator) of an electric motor or generator, designed to generate or receive a magnetic field. These coils are arranged in slots, frequently in halves, and secured with insulation and supports to withstand operational stresses. When alternating current power is applied, the coils create a rotating magnetic field, producing torque in a motor, or when a rotor’s magnetic field changes, it induces current in the stator coils to generate electricity in a generator.
Stator core – It is the stationary, iron-based component of an electric motor or generator which houses the stator windings and creates a magnetic field to interact with the rotor. It is constructed from stacked, thin sheets of electrical or silicon steel, known as laminations, which are coated with an insulating material to minimize eddy currents and hysteresis losses, hence improving the machine’s efficiency.
Stator voltage – It is the electrical potential difference applied to the windings of a motor’s stationary part (the stator), creating a magnetic field that interacts with the rotor to produce mechanical power. It can refer to the applied voltage in a motor, which controls its torque and speed, or, in the case of generators the voltage generated in the stator windings by a rotating magnetic field.
Status report – It is a document providing a regular, concise update on the current state of a project, including progress, completed tasks, risks, issues, and next steps, to keep stakeholders informed and allow for informed decision-making. It compares the project’s current position against its plan to monitor costs, time, and work, using charts and graphs to visualize data, and is important for maintaining alignment and identifying problems early.
Stave bearing – It is a sleeve bearing consisting of several axially held slats or staves on the outer surface of which the bearing material is bonded.
Stave cooler – Stave coolers with water circulating in them are installed between the shell of the blast furnace and the refractory lining in the upper part of the furnace to protect these components from heat radiation.
Stave construction – It consists of attaching staves to polygon-shaped heads in the building of cylindrical bodies. It is also standard method used in making semi-circular core boxes.
Steadite – It is a hard structural constituent of cast iron which consists of a binary eutectic of ferrite, containing some phosphorus in solution, and iron phosphide (Fe3P). The eutectic consists of 10.2 % phosphorus (P) and 89.8 % iron (Fe). The melting temperature is 1,050 deg C.
Stead’s brittleness – It is a condition of brittleness which causes transcrystalline fracture in the coarse grain structure that results from prolonged annealing of thin sheets of low-carbon steel previously rolled at a temperature below around 705 deg C. The fracture normally occurs at around 45-degee to the direction of rolling.
Steady flow – It is characterized by fluid properties like velocity, pressure, and density remaining constant over time at any given point within the flow field. This means that if people are to observe a specific location in a steady flow, they do not see any changes in these properties as time progresses. It is important to note that while steady flow implies no change with time at a point, the properties can still vary from one point to another within the flow field.
Steady loads – These are the loads which do not change in intensity or which change so slowly that they can be regarded as steady.
Steady-rate creep – It is that creep which is occurring at a minimum and almost constant rate.
Steady-state – It is the condition of a control system where changes because of some disturbances are no longer occurring at a significant rate.
Steady state analysis – It evaluates a system’s behaviour under conditions where all dynamic variables are constant over time. It involves observing the system’s behaviour as time approaches infinity or after transient effects (temporary fluctuations) have dissipated, assuming constant loads and parameters, to understand its long-term performance and stability. This simplifies analysis by allowing for the use of less complex equations and is applied in fields like electrical engineering to study alternating current circuits, structural analysis for constant loads, and control systems to assess long-term output.
Steady-state continuous casting – It refers to a condition where the continuous casting process is operating in a consistent and predictable manner, with no significant changes in key parameters like casting speed, mould temperature, or the solid-liquid interface. This means the process is in equilibrium, maintaining a stable output of solidified metal.
Steady-state crack propagation – It occurs when a crack grows at a constant speed under a constant driving force, leading to a stable and unchanging stress field at the crack tip. This condition simplifies fracture analysis since load and displacement become time-independent. It is frequently associated with a stable plastic zone and a constant crack growth resistance, although this can be fully yielded and uncontained in some cases, like thin metal sheets.
Steady state flow – It describes a condition where fluid properties at any given point within a system, such as flow rate and pressure, remain constant over time. This means the characteristics of the flow do not change with time, allowing for simplified analysis and calculation in engineering designs, though real-world systems can experience some temporal or spatial variations.
Steady-state model – It represents a system in which its key variables, such as pressure, temperature, flow rate, or composition, do not change over time. This means that all time-dependent terms in the system’s equations are zero, simplifying analysis by eliminating transients or dynamic responses and providing a snapshot of the system’s equilibrium behavior. Steady-state models are used to understand a system’s operational condition once initial disturbances have settled and it has reached a stable state.
Steam – It is the gaseous state of water, produced when liquid water is heated to its boiling point and transforms into a gas. It is often visible as a mist or cloud of condensed water droplets, especially when steam from boiling water encounters cooler air. It is the vapour phase of water, unmixed with other gases. It is the technical term used for water vapour, the gaseous phase of water, which is formed when water boils. Technically speaking water boils at a temperature of 100 deg C and at atmospheric pressure.
Steam atomizing oil burner – It is a burner for firing oil which is atomized by steam. It can be of the inside or outside mixing type.
Steam binding – It is a restriction in circulation because of a steam pocket or a rapid steam formation.
Steam boiler – A steam boiler is an enclosed container where water is heated under controlled conditions to convert it into steam. Boiler is basically a heat exchanger where heat is transferred to water. It is also sometimes referred to as steam generator.
Steam condensate – It is liquid water which forms when steam cools and loses its latent heat, typically after transferring its energy to a product or system. This liquid is frequently collected, either for re-use in boilers to save on water costs, or as a byproduct of heating processes. The quality of the condensate can vary, as it can contain dissolved gases like carbon di-oxide which can cause corrosion in piping systems, making purification processes like condensate polishing necessary.
Steam cooling – It involves using steam, or a water-steam phase change process, to remove heat from a component or system, frequently improving efficiency and performance by taking advantage of the latent heat of evaporation or the superior heat transfer effectiveness of steam compared to air. This can range from using steam directly as a coolant in high-temperature applications like gas turbines to using steam-jet or evaporative cooling systems which utilize the phase change of water to absorb heat.
Steam cure (open) – It is a method of vulcanizing rubber parts by exposing them directly to steam in a vulcanizer.
Steam curing – It is a process where concrete or other materials are exposed to steam, typically at atmospheric or higher pressures, to accelerate their hardening and strength development. This method involves maintaining a high humidity and high temperature, promoting faster hydration and strength gain.
Steam distribution system – It is a network of pipes, valves, and accessories which efficiently and safely transports steam from its source, like a boiler, to the equipment where its heat energy is needed for industrial processes, space heating, or power generation. It is to deliver steam at the correct pressure and quality while minimizing heat loss and managing the inevitable condensate (water formed as steam cools) to prevent issues like water hammer and corrosion.
Steam drum – A steam drum is a standard feature of a water tube boiler. It is a reservoir of water / steam at the top end of the water tubes. The drum stores the steam generated in the water tubes and acts as a phase separator for the steam / water mixture. The difference in densities between hot and cold water helps in the accumulation of the ‘hotter’-water / and saturated-steam into the steam-drum.
Steam drying – It refers to a convective drying process which uses super-heated steam (steam heated beyond its boiling point) to remove water from materials, offering advantages like faster drying rates, better heat transfer, energy savings, and often improved product quality compared to air drying. This method utilizes the high thermal conductivity and heat capacity of steam, allowing for more efficient and compact drying systems.
Steam ejector – It is a device which uses high-pressure steam as a motive fluid to create a vacuum, effectively removing gases or vapours from a system. It operates on the principle of Bernoulli’s equation, converting the steam’s pressure energy into high velocity through a nozzle. This high-speed jet entrains (draws in) the gas or vapour to be removed, mixing it within the ejector. The mixture then flows into a diffuser, where the velocity decreases, and the pressure increases, discharging the gases from the system.
Steam engine – It is a heat engine which performs mechanical work using steam as its working fluid. It is a heat engine which converts the thermal energy of steam into mechanical work, typically by expanding steam in a cylinder to drive a piston. This expansion of steam under pressure pushes a piston, which then uses connecting mechanisms to generate rotational force, hence powering several machines and vehicles.
Steam gasification – It is a high-temperature thermo-chemical process which converts carbon-containing materials into a gaseous fuel (synthesis gas) using steam as the primary agent, typically in an oxygen-deficient environment. This method is highly efficient for producing hydrogen-rich, nitrogen-free syngas from feedstocks like coal, biomass, or waste, which can then be used to generate heat, power, or valuable chemicals.
Steam gauge – It is a gauge for indicating the pressure of steam.
Steam generating unit – It is a unit to which water, fuel, and air are supplied and in which steam is generated. It consists of a boiler furnace, and fuel burning equipment, and can include as component parts water walls, superheater, reheater, economizer, air heater, or any combination thereof.
Steam generator – It is another name of steam boiler. It is a device which uses a heat source to convert water into steam, which can then be used for different applications like powering machinery or generating electricity.
Steam generator tube – It is a critical component, typically a tube or a bundle of tubes, within a steam generator which transfers heat from a high-temperature primary coolant to a secondary fluid (like water), converting it into steam under pressure. These tubes function as a heat exchanger and a safety barrier, most notably in nuclear power plants, to prevent the highly radioactive primary coolant from contaminating the secondary side used to power turbines.
Steam hammer – It is a type of drop hammer in which the ram is raised for each stroke by a double-action steam cylinder and the energy delivered to the work-piece is supplied by the velocity and weight of the ram and attached upper die driven downward by steam pressure. The energy delivered during each stroke can be varied.
Steam humidifier – It is a device designed to increase the moisture content (or water vapour) in an air stream or a specific volume of air, typically by using a steam source to boil water and then dispersing that steam into the air-stream to regulate the humidity levels in a building’s air conditioning system. These systems frequently rely on a humidistat or other sensors to monitor environmental conditions and activate the humidifier to meet a target humidity setpoint.
Steaming – When rain falls on hot briquetted iron (HBI) piles, the material absorbs some water (around 3 %) because of the capillary effects on the exposed surfaces and releases water vapour. This effect is called ‘steaming’. At a temperature above 50 deg C, hot briquetted iron re-oxidizes when heavily wetted and create heat, which in turn results in evaporation of the water. Hot briquetted iron piles steam until the water is evaporated, the reoxidation reaction stops, and the material cools to ambient temperature. Hence, water is not to be sprayed on steaming piles of hot briquetted iron.
Steam injection – It is a process where steam is introduced into a system to transfer heat or improve a process, such as oil recovery or heating liquids. In oil recovery, it is used to heat heavy crude oil and reduce its viscosity, making it easier to extract. In heating applications, steam is injected directly into a liquid or slurry to transfer heat and raise its temperature.
Steam methane reforming (SMR) – It is a process where methane, the primary component of natural gas, reacts with steam in the presence of a catalyst to produce hydrogen, carbon mono-oxide, and carbon di-oxide. It is a widely used method for hydrogen production, frequently used in industrial settings. The process is exothermic, meaning it needs an input of heat.
Steam phase diagram – It is the data provided in the steam tables which is expressed in the graphical form.
Steam piping system – It is a network of pipes, valves, fittings, and accessories designed to safely and efficiently transport steam from its generation source (like a boiler or reactor) to points of use for different applications, such as heating, power, or industrial processes. Key engineering considerations include managing high pressure and temperature, minimizing heat loss and condensate, preventing water hammer and corrosion, and ensuring the steam reaches the point of use at the required pressure, temperature, and dryness.
Steam power plant – It is a facility which generates electricity using steam as its primary working fluid, converting heat energy into mechanical and electrical energy. It typically consists of a boiler, turbine, generator, and condenser, working together to produce electricity.
Steam pre-heater – It is frequently called a steam coil air pre-heater (SCAPH). It is a device, typically a heat exchanger, which uses steam to heat a fluid, normally combustion air for boilers. Its main function is to improve energy efficiency and prevent issues like acid dew point corrosion by ensuring the incoming air is at a higher temperature, which can also help during low-load or start-up conditions.
Steam pressure – The conventions of low, medium, and high-pressure steam vary as defined by the various steam users around the country. Typically, steam below 350 kilo-pascals is termed as low-pressure steam. Steam above 350 kilo-pascals but below 1,750 kilo-pascals is termed as medium pressure steam. Steam above 1,750 kilo-pascals is termed as high-pressure steam. Some users define their steam above 4,000 kilo-pascals as ultra-high-pressure steam.
Steam pump – It is a pump powered by a steam engine, either directly or through a combined engine and pump mechanism. It can also refer to a type of pump which uses steam to create pressure, such as the Savery engine or the Pulsometer pump. These pumps have historical importance for applications like mine drainage and public water supply.
Steam purity – It is the degree of contamination. Contamination is expressed in parts per million (ppm).
Steam quality – It is the percent by weight of vapour in a steam and water mixture.
Steam Rankine cycle – The most frequently used system for power generation from waste heat involves using the heat to generate steam, which then drives a steam turbine. The traditional steam Rankine cycle is the most efficient option for waste heat recovery from exhaust streams with temperatures above 340 deg C. At lower waste heat temperatures, steam cycles become less cost effective, since low pressure steam needs larger equipment. Moreover, low temperature waste heat cannot provide sufficient energy to superheat the steam, which is a requirement for preventing steam condensation and erosion of the turbine blades. Hence, low temperature heat recovery applications are better suited for the organic Rankine Cycle or Kalina cycle, which use fluids with lower boiling point temperatures compared to steam.
Steam reforming – It is a widely used, mature industrial process that converts hydrocarbon-based feedstocks, such as methane or methanol, into a mixture of hydrogen (H2) and carbon mono-oxide (CO) using high-temperature steam and a catalyst. The main goal of this endothermic reaction is to maximize hydrogen production, which is frequently followed by a water-gas shift reaction to convert the carbon mono-oxide into more H2 and carbon di-oxide (CO2). The pure hydrogen is then separated for use in several applications like ammonia synthesis, and the process is carefully controlled by temperature, pressure, and steam-to-fuel ratio to optimize product yield.
Steam separator – It is a device for removing the entrained water from steam.
Steam space – Steam space is the space above the water line in a steam boiler where the boiling water and steam can separate from each other. The space also acts as a pressure reservoir to accommodate small load fluctuations.
Steam stop valve – Steam stop valve is the main valve on the steam line leaving the boiler. It is to be able to positively halt the flow of steam from a boiler.
Steam system – Steam moves from a high-pressure location to a lower pressure location. In doing so it uses some of its own energy which is seen as pressure drop. Additionally, heat losses during distribution causes a fraction of the steam to condense to form condensate. This is fundamental to understanding the operation of steam systems and how they are designed. There are a number of items of basic line equipment which are common to all steam systems such as different types of valves, pressure and temperature gauges, strainer and steam traps etc.
Steam tables – Steam tables are the compilation of experimental results of the thermodynamic properties (namely specific volume, internal energy, sensible heat, latent heat, and saturation temperature etc.) of 1 kilogram of steam in a tabular column. These are available either on pressure basis or on temperature basis. These tables are useful for steam engineering calculations, as vapours do not obey gas laws. The pressures in the steam tables are in bar (absolute). In case of gauge pressures, they are to be converted in to absolute pressure by adding atmospheric pressure to them. All the values given in the steam tables are reckoned above 0 deg C. If the initial temperature of water is other than 0 deg C, the enthalpy of steam is to be calculated from the steam tables by deducting the quantity of heat contained initially by the water.
Steam tracing – It is a heat tracing method which uses steam circulated through small-bore tubes (tracer lines) wrapped around or attached to a process pipe to maintain the process fluid’s temperature, preventing it from solidifying, freezing, or separating. By utilizing the latent heat of steam as it condenses into water, steam tracing efficiently transfers heat to the process fluid, ensuring it stays within a desired temperature range for optimal flow, viscosity, and reliable operation in industries like chemical processing and oil and gas.
Steam traps – These are devices which are used to discharge condensate and non-condensable gases with a negligible consumption or loss of live steam. Steam traps are devices which exist in low lying places within a pressurized steam line to release condensate and non-condensable gases from the system. Steam lines are normally used to open / close control valves, and heat trace pipelines to prevent cooling etc. These steam traps are generally used to save money on the prevention of corrosion and loss of steam. When these traps fail, it means loss of steam and hence the money. There can be several numbers of steam traps for a technological process, and hence it is important to maintain and check the condition of each trap at a planned interval. The checks can be done by visual, thermal, or acoustic techniques. There are several types of steam traps which differ in the properties they operate on including mechanical (density), temperature, and thermo-dynamic (pressure). Majority of steam traps are nothing more than automatic valves. They open, close, or modulate automatically.
Steam treatment – It is the treatment of a sintered ferrous part in steam at temperatures between 510 deg C and 595 deg C in order to produce a layer of black iron oxide (magnetite, or ferrous-ferric oxide, (FeO·Fe2O3) on the exposed surface for the purpose of increasing hardness and wear resistance.
Steam turbine – It is a device which extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Since the turbine generates rotary motion, it is particularly suited to be used to drive an electrical generator. It is a machine or heat engine which extracts thermal energy from the pressurized steam and uses it to do mechanical work on a rotating output shaft. Fabrication of a modern steam turbine involves advanced metalwork to form high-grade steel alloys. The steam turbine is a form of heat engine which derives much of its improvement in thermodynamic efficiency from the use of multiple stages in the expansion of the steam, which results in a closer approach to the ideal reversible expansion process.
Steam turbine blade – It is a component designed to convert the thermal and kinetic energy of high-pressure steam into mechanical, rotational energy. Blades are arranged in stages of stationary nozzles (which accelerate the steam) and rotating blades (which are driven by the steam) on a turbine rotor. They are to be engineered from advanced, high-temperature-resistant materials to withstand harsh operating conditions like high stress and extreme temperatures, ensuring efficient and durable power generation.
Steam valve – It is a mechanical device which regulates the flow, pressure, and temperature of steam within a system. These valves are designed to withstand high-temperature and high-pressure conditions and are crucial for controlling steam for different applications, including power generation, and industrial heating. Common types include globe, gate, and butterfly valves, each selected for specific applications based on their design and operating characteristics.
Steckel mill – It is a cold reducing mill having two working rolls and two back-up rolls, none of which is driven. The strip is drawn through the mill by a power reel in one direction as far as the strip allows and then reversed by a second power reel, and so on until the desired thickness is attained.
Steel – It is an iron-base alloy, malleable in some temperature ranges as initially cast, containing manganese, normally carbon, and frequently other alloying elements. In carbon steel and low-alloy steel, the maximum carbon is around 2 % and in high-alloy steel, around 2.5 %. The dividing line between low alloy and high-alloy steels is normally regarded as being at around 5 % metallic alloying elements. Steel is said to be differentiated from two general classes of ‘irons. Namely the cast irons, on the high carbon side and the relatively pure irons such as ingot iron, carbonyl iron, and electrolytic iron, on the low-carbon side. In some steels containing extremely low carbon, the manganese content is the principal differentiating factor, steel normally containing at least 0.25 % manganese and ingot iron considerably less.
Steel arch – It is a curved structural element made of steel which spans an opening, supporting vertical loads by converting them into axial compressive forces that are transferred to its supports. Unlike beams which mainly resist bending, steel arches efficiently redirect loads mainly through thrust, leading to substantial material savings and allowing for large, aesthetically pleasing, and durable structures like bridges, roofs, and large-span buildings.
Steel armour wire – It refers to galvanized steel wires helically stranded around an electrical cable core to provide robust mechanical protection, forming a type of steel wire armour (SWA) cable. This durable outer layer protects the internal conductors from impact, crushing, and rodent damage, making these cables ideal for heavy-duty, direct-burial applications, industrial settings, and other harsh or hostile environments requiring enhanced safety and long-term reliability.
Steel based rolls – Steel rolls can be cast or forged. They are much stronger and tougher than iron rolls and hence are used where an iron roll is considered not strong enough. They permit heavier draughts to be used especially where deep grooves are needed. Breakages due to shock loading are much less likely to occur and the properties can be varied considerably by suitable heat treatment. However, carbon steel rolls wear more quickly than iron rolls because of their low hardness.
Steel beams – These beams are important type of structural elements which play a key role in creating a safe load path to transfer the weight and forces on a structure to the foundations and into the ground. These beams are a member of the structure which is subjected primarily to transverse load and negligible axial load. The cross section of the beam provides superior load bearing support. The superior spanning capability of the steel beam means fewer columns and more usable space. Steel beam is a type of building material which is used to construct several structures. It can be used in many types of building applications.
Steel-bonded titanium carbide – It is a composite material where titanium carbide (TiC) particles are embedded within a steel matrix. This combination leverages the high hardness and wear resistance of titanium carbide with the toughness and ductility of steel. The materials are created using powder metallurgy techniques, where the titanium carbide and steel powders are combined, pressed, and then heated to form a dense, bonded structure.
Steel bridge – It is a structure designed to span physical obstacles, using steel as its primary structural material. These bridges are valued for steel’s high tensile strength, durability, and adaptability, allowing for different designs like truss, beam, or suspension bridges for different applications including highways, railways, and pedestrian use. Steel’s high strength-to-weight ratio enables longer spans and reduces construction costs, while its modularity facilitates quick assembly and repair.
Steel casting – It is a process of casting liquid steel into shapes. In this process, molten steel is poured into a mould to create a specific shape. Steel casting is used when strength is crucial.
Steel catenary riser (SCR) – It is a steel pipe which hangs freely from a floating offshore platform to the seabed, forming a natural catenary curve because of gravity and buoyancy. Steel catenary risers are a cost-effective choice for deepwater oil and gas production and water injection lines, providing a flexible conduit for fluids while self-compensating for the platform’s vertical movements. Key design considerations include managing fatigue at the touchdown point and the hang-off location.
Steel chain slings – These slings are made from steel chains. Chains are normally used because of their strength and ability to adapt to the shape of the load. However, care is needed to be taken, using alloy steel chain slings since these slings are subject to damage by sudden shocks. Misuse of steel chain slings can damage the sling, resulting in sling failure and possible accident.
Steel chemistry – It refers to its definition as an alloy of iron and carbon, where the specific proportions of carbon and added alloying elements (like chromium, nickel, or manganese) determine the material’s unique properties, such as strength, hardness, ductility, and corrosion resistance. This elemental composition dictates steel’s mechanical behaviour and microstructure, making it a fundamental and versatile material for structural and manufacturing applications.
Steel cleanliness – It refers to a steel’s purity, which is characterized by inclusions, like non-metallic particles, which occur during the steelmaking process. Minimizing inclusions is key to achieving clean, high-quality steel. It is an important factor of steel quality and the demand for cleaner steels increases every year. However, the term ‘clean steel’ is used with caution by the metallurgists. This is because of (i) the varying cleanliness demands for steels for different applications, (ii) varying cleanliness in steels produced in different operations, and (iii) the normal understanding of the term ‘clean steel’, which some literally interpret as meaning the absence of inclusions in the steel. Steel cleanliness has implications from both operational and product performance points of view.
Steel composition – It refers to the specific blend of iron and carbon, plus different alloying elements, which defines steel’s properties like strength, hardness, and corrosion resistance. Engineers select a specific composition by controlling the quantities of these elements to create steels suitable for diverse applications, such as the high strength needed for structural components or the improved toughness needed for impact resistance.
Steel conduit – It is a durable metal tube used to encase and protect electrical wiring, providing physical strength, earth continuity, and shielding from environmental factors like moisture, dust, and impact. Different types exist, including rigid (thick-walled) and intermediate (thinner-walled) metal conduit, each offering varying degrees of mechanical stiffness, corrosion resistance, and suitability for different applications.
Steel construction – It is a method of building structures mainly using a steel skeleton of fabricated components, (such as beams, columns, and bracing) connected by bolts or welds. These pre-fabricated steel parts are designed to withstand loads, forming a load-bearing system for several structures like buildings, bridges, and industrial facilities. Steel construction’s advantages include a high strength-to-weight ratio, rapid on-site assembly, flexibility in design, and sustainability because of the steel’s recyclability.
Steel-cord conveyor belt – Steel-cord conveyor belts are made with a single layer of parallel steel cords completely embedded in the rubber as the tension element. The carcass of steel-cord belt is available in two types of construction. The all-gum construction uses only the steel cords and rubber while the fabric-reinforced construction has one or more plies of fabric above and / or below the cords but separated from the cords by the cord rubber. Both types have appropriate top and bottom covers. Steel cord construction with breaker (reinforcing fabric) (i) prevents length-wise tearing by foreign substances or sharp objects, (ii) prevents broken steel cord from protruding through cover rubber, (iii) provides high withdrawal strength (in stationary tests), and (iv) reduces risks for belt breakage by impact.
Steel cord pullout strength – It is the adhesion between rubber and steel cord, normally determined in the ‘supply status’ (Fa) and after additional thermal treatment (Fv). A typical minimum requirement is 15d+15 for Fa and 15d+5 for ‘Fv’, e.g., 5 millimeters steel cord diameter times 15 + 15 = 90 Newtons per millimeter.
Steel core – It refers to a central structural or magnetic component made of steel which provides strength, channels magnetic flux, or serves as a backbone for other elements. The specific function and composition vary by application; for example, it can be a steel-wire ACSR (aluminium conductor steel reinforced) power cable core for strength, a silicon steel core in an electrical transformer to conduct magnetic fields efficiently, or even a foundational element in a building’s structure.
Steel corrosion – It is the electro-chemical process by which steel deteriorates because of a chemical reaction with its environment, mainly involving oxidation of the iron to form iron oxides (rust). This natural, but frequently undesirable, degradation of steel’s properties leads to a loss of strength and structural integrity, increasing maintenance costs and posing safety risks. The process needs the presence of both moisture and an oxidant, like oxygen, and can be influenced by factors such as temperature, humidity, and the presence of corrosive substances.
Steel fibre – It is a short, discrete piece of steel, typically with an aspect ratio (length-to-diameter) between 20 and 100, which is small enough to be randomly dispersed in a concrete mix. When added to concrete, these fibres improve substantially the material’s toughness, ductility, and resistance to cracking, impact, and fatigue. Common applications include industrial floors, roads, and structural elements, where they act as a supplementary reinforcement to conventional steel rebar to improve overall performance and durability
Steel fibre concrete – It is a composite material which combines traditional concrete with randomly dispersed, short, discontinuous steel fibres to improve its mechanical properties, including ductility, toughness, energy absorption, and resistance to cracking, impact, and fatigue. These fibres act by bridging cracks, transferring stresses, and developing post-crack strength, making the material suitable for applications needing high performance, such as industrial floors, roads, and tunnels.
Steel framed building – It uses a ‘skeleton’ of vertical steel columns and horizontal steel beams, frequently I-beams, connected by welding, bolting, or riveting to form a rigid structure which supports the floors, walls, and roof. This system transfers loads to the foundation and provides stability, forming the important structural core around which the rest of the building is assembled.
Steel grade – It is a classification which denotes a steel’s specific chemical composition and physical properties, such as strength, hardness, and corrosion resistance. These grades are defined by international and national standards organizations to ensure consistent material performance, allowing designers to select the right steel for a particular application based on its characteristics and needed mechanical qualities.
Steel heat treatment – It is a controlled process of heating and cooling steel in a solid state to alter its internal microstructure, thereby changing its physical and mechanical properties without changing its shape. This technique is used to improve specific characteristics such as hardness, strength, ductility, and impact resistance, making the steel suitable for its intended engineering application. Common methods include annealing, normalizing, quenching, and tempering, each achieved through precise heating, holding, and cooling cycles.
Steel H pile – It is a structural beam with an H-shaped cross-section, mainly used as a bearing pile in deep foundation applications. These piles are driven or drilled into the ground to transfer the weight of a structure to deeper, more stable soil layers. They are known for their strength, durability, and ability to handle significant loads.
Steel ingot – It is a solid, semi-finished block of steel cast from molten metal into a mould, serving as the main raw material for further shaping into finished steel products like bars, plates, and beams. Ingots are processed through hot or cold working, such as rolling and forging, to reduce their size and form them into the specific shapes and dimensions needed for several applications.
Steel intensity – It is the quantity of steel used per unit of gross domestic product. Intensity reflects the secular demand for steel, as opposed to cyclical demand. The quantity of steel used in vehicles and the popularity of alternative materials affect the intensity, or how much steel is needed per unit produced. The state of the economy, however, determines the number of units.
Steel-intensive products – These are consumer products such as automobiles and appliances which, because so much of their weight is from steel, show a high demand correlation with steel.
Steel jacket – It refers to a steel casing or framework used for two main purposes namely (i) to reinforce existing reinforced concrete columns by adding a protective steel shell to increase strength, ductility, and prevent failure, and (ii) to describe the lattice-like structural framework used to support offshore platforms and turbines in deep water, providing stability by connecting vertical legs with horizontal and diagonal bracing.
Steelmaking process – It refers to the transformation of raw materials like iron ore and scrap into steel by melting, purifying, and alloying them. This complex metallurgical process involves removing impurities such as excess carbon, silicon, sulphur, and phosphorus, and adding alloying elements to achieve desired steel properties. Major methods include basic oxygen furnace (BOF), which uses oxygen to refine molten iron, and electric arc furnace (EAF) as well as electric induction furnace (EIF), which use electricity to melt scrap.
Steelmaking slag – It is a by-product of steelmaking. It is produced during the separation of the liquid steel from impurities in steelmaking furnaces. It is a liquid product generated during the production of steel. It can be categorized as carbon steel slag, or stainless-steel slag as per the type of steel produced, or as primary steelmaking slag such as basic oxygen furnace slag, electrical furnace (electric arc furnace, and induction furnace) slag, secondary steelmaking slag, or continuous casting slag according to the steelmaking process. Steelmaking slag is defined as the solid material resulting from the interaction of flux and impurities during the smelting and refining of steels. The American Society for Testing Materials (ASTM) defines steelmaking slag as ‘a non-metallic product, consisting essentially of calcium silicates and ferrites combined with fused oxides of iron, aluminum, manganese, calcium and magnesium, that is developed simultaneously with steel in basic oxygen, electric arc, or open hearth-furnaces’.
Steelmaking slag scrap – Steelmaking slag scrap is normally considered to be a low-grade melting material. This material consists of irregular steel nuggets which have been separated magnetically from crushed slag. Melting yield with this category of scrap normally ranges from 70 % to 80 %.
Steel micro-structure – It defines the size, arrangement, and distribution of phases (like ferrite, pearlite, and martensite), grains, and defects within the material, visible at microscopic levels. This internal structure, determined by composition and processing, directly controls steel’s mechanical properties, such as strength, hardness, and ductility, allowing engineers to select or design steel for specific applications.
Steel mill – It is also called steel plant or steelworks. It is an industrial facility which manufactures steel by processing raw materials like iron ore and scrap metal through processes such as melting, refining, casting, and rolling. Engineers are crucial for the design, operation, and optimization of these energy-intensive plants, which produce steel (an alloy of iron and carbon) which serves as a foundational material for several industries and infrastructure projects.
Steel pile – It is a long, slender steel element driven or embedded into the ground to support loads and provide stable foundations for several structures like buildings, bridges, and coastal structures. They act as a foundation member, transferring the weight of the structure to deeper, more stable soil or rock layers.
Steel pipe pile – It is a cylindrical steel tube, typically driven or drilled into the ground, used as a structural support for foundations, retaining walls, and other civil engineering projects. These piles transfer loads from a structure to the soil or bedrock below, providing stability and resistance to ground movements.
Steel powder metallurgy – It is a manufacturing process which involves transforming steel into a powder, then compacting it into a desired shape and heating it (sintering) at a temperature below its melting point to bond the particles into a solid, complex part. This versatile technique allows for the precise production of intricate steel components with improved properties, frequently with lesser waste and lower material loss compared to traditional methods.
Steel processing technology – It refers to the methods and techniques used to transform raw materials, mainly iron ore and scrap, into steel, which is a versatile and durable material with a wide range of applications. This process involves melting, refining, and shaping to achieve desired properties and forms of steel.
Steel refining – It is the process of purifying crude iron (hot metal, pig iron), mainly by reducing its carbon content and removing other impurities, to produce steel with desired composition and properties. This involves several techniques like oxidation, the addition of alloying elements, and the removal of unwanted elements like sulphur, phosphorus, and oxygen. The final steel composition is determined by the specific grade of steel being produced.
Steel reinforced polymer (SRP) – It is a composite material consisting of ultra-high-tensile-strength steel cords embedded within a polymeric matrix, such as an epoxy or polyester resin. It is used for strengthening concrete and masonry structures, steel reinforced polymer combines the high tensile strength of steel with the corrosion resistance and flexibility of polymers, making it an effective solution for retrofitting and repairing civil engineering structures.
Steel reinforcement – In concrete structure, the steel reinforcement used can be in the form of bars or welded wire fabric. Reinforcement bars are referred to as plain or deformed. The deformed bars, which have ribbed projections rolled onto their surfaces (patterns differing with different manufacturers) to provide better bonding between the concrete and the steel, are used for almost all applications. Plain bars are not used very often except for wrapping around longitudinal bars, primarily in columns. Plain round bars are indicated by their diameters in mm. Reinforcement bars were formerly manufactured in both round and square cross sections, but today all bars are round. Welded wire fabric is also frequently used for reinforcing slabs, pavements, and shells, and places where there is normally not sufficient room for providing the necessary concrete cover required for regular reinforcement bars. The mesh is made of cold-drawn wires running in both directions and welded together at the points of intersection. The sizes and spacings of the wire may be the same in both directions or may be different, depending on design requirements. Wire mesh is easily placed and has excellent bond with the concrete, and the spacing of the wires is well controlled.
Steel reinforcement bar – It is also known as rebar, reinforcing bar, reinforcing steel and reinforcement steel. Steel reinforcement bar is a versatile constructional material which is widely used in the construction industry for making of the reinforced concrete. The steel reinforcement bars normally consist of such shape and size that they may easily be bent and placed in the concrete so as to form a monolithic structure. Steel reinforcement bars are also used to confer resistance to concentrated loads by providing enough localized resistance and stiffness for a load to spread through a wider area. They can also be used to hold other steel bars in the correct position to accommodate their loads.
Steel scrap – It also referred to as scrap comes from ‘end of life’ products (old or obsolete scrap) as well as scrap generated from the steel manufacturing processes (new, prime or prompt scrap). It is metal which contains iron. Steel scrap can be processed and re-melted repeatedly to form new products. Because of the value of metal in the steel scrap, it is recycled or reused wherever it is possible. In fact, steel scrap is being recycled long before present awareness of environmental concerns started. The primary sources for steel scrap are those products, for which steel is the main constituent. These are namely, vehicles (including ships and rail coaches and wagons), white goods, products of construction, machinery, electrical and electronic equipment, and packaging etc.
Steel shell – It refers to a protective outer layer made from steel, frequently utilized in the design of transport or storage packages for nuclear fuel because of its mechanical resistance and impact resistance. These shells are typically forged and machined, with thicknesses ranging from 200 milli-meters to 300 milli-meters and are treated to prevent corrosion.
Steel shot – It refers to spherical, hardened steel abrasive particles used for surface treatment processes like cleaning, rust removal, and shot peening to improve material properties such as fatigue resistance. These durable, dense, and reusable pellets are produced from molten steel and come in different sizes to suit different applications in several industries.
Steel slag – It is the non-metallic, solid by-product of the steel manufacturing process, mainly a complex mixture of metal oxides and silicates which forms when impurities are separated from molten steel. It is cooled and processed for use as an engineering material, such as an aggregate in asphalt and concrete, a supplementary cementitious material, or as a component in civil infrastructure.
Steel strapping – It consists of banding and packaging material which is used to close and reinforce shipping units, such as bales, boxes, cartons, coils, crates, and skids.
Steel structure – It is a framework composed mainly of interconnected structural steel components, such as beams, columns, and bracing, designed to carry loads, provide rigidity, and resist forces like torsion, bending, and compression. These structures are valued for steel’s high strength-to-weight ratio, durability, and suitability for different applications from high-rise buildings to bridges and industrial plants. Common components include I-beams, channels, angles, and hollow structural sections (HSS), connected by bolts or welding to form a complete system.
Steel stud – It is a vertical framing member, typically made from cold-formed steel channels, used to create the structural framework for interior and exterior walls and partitions in buildings. These non-combustible components provide strength, durability, fire resistance, and a non-load-bearing alternative to wood studs, especially in commercial and industrial projects. They are installed between horizontal metal tracks, spaced to support sheathing like drywall and resist forces like axial compression and wind loads.
Steel teeming ladle (STL) – It is needed in a steel plant to contain and transport liquid steel from the steelmaking furnace to the casting facility. These days, steel teeming ladle is used in a significantly more complex manner than the older steel melting shops where ladles have been used simply to transport liquid steel from a steelmaking furnace to the ingot moulds. Other functions carried out in the steel teeming ladle are temperature control, deoxidation, additions of carburizer and ferro-alloys and inclusion floatation. In the recent past, the demand for several grades of steel with stringent specifications has increased considerably. These steels are produced using secondary refining processes. The lining of the steel teeming ladle is required to withstand increasingly severe service conditions associated with the secondary refining processes. These severe conditions are longer holding time, higher liquid temperature and arc / chemical heating. Rinsing with inert gas and degassing of the liquid steel, alloying and use of synthetic slag also accelerate the wear of lining. Because of these activities the demand on the quality of steel teeming ladle refractories has increased very much.
Steel transmission towers – These are space steel structures made by the latticework of steel girders and diagonal braces. The individual pieces are made from rolled steel profiles and then bolted together at the site. Corrosion protection of all tower parts is made by hot dip galvanizing. Weathering steel is also used for corrosion protection. Steel transmission towers have higher mechanical strength, longer life, and permit the use of longer spans. The risk of interrupted service because of the broken or punctured insulation is considerably reduced owing to longer spans. Tower footings are normally grounded by driving steel rods into the earth. This minimizes the lightening troubles as each tower acts as a lightning conductor. Majority of the steel transmission towers are designed to support one or two circuits, although some have been designed to support three or four circuits. Each circuit consists of three phases.
Steel tubular products – These are hollow steel sections, normally used in several applications because of their strength, durability, and versatility. They can be round, square, or rectangular, and are produced through either seamless or welded methods. These products are used in construction, machinery, and automotive industries, among others.
Steel valve – It is a mechanical device, typically made from carbon, alloy, or stainless steel, which controls the flow, pressure, or direction of a fluid (liquid or gas) within a system. These valves are crucial components in pipelines and processing plants, functioning to block flow, regulate it precisely, or divert it to different paths, and are selected based on the specific needs of high-pressure, high-temperature, or corrosive environments.
Steel wire gauge (SWG) – It refers to a system used to measure the diameter of steel wire. It is a standardized method for classifying and identifying steel wire based on its thickness. Essentially, it is a numerical code which tells a people how thick or thin the wire is, with higher gauge numbers normally indicating thinner wire.
Steel wire rod – It is a semi-finished product which is rolled from steel billet in a wire rod mill and is used primarily for the manufacture of wire. For a steel plant it is a finished product. The steel for wire rod is produced by all the modern steelmaking processes, including the basic oxygen and electric furnace processes. Steel wire rod is usually cold drawn into wire suitable for further processing such as cold rolling, cold heading, cold upsetting, cold extrusion, cold forging, or hot forging.
Steel wire rope – It is also known as steel cable. It is a type of rope which consists of several strands of steel wire laid (twisted) into a helix. It is a preferred lifting device for several reasons. Its unique design consists of multiple steel wires which form individual strands laid in a helical pattern around a core. This structure provides strength, flexibility, and the ability to handle bending stresses. Different configurations of the material, wire, and strand structure provide different benefits for the specific lifting applications. These benefits include strength, flexibility, abrasion resistance, crushing resistance, fatigue resistance, corrosion resistance, and rotation resistance.
Steel wire rope slings – These slings are made of steel wire rope. Wire rope is composed of individual wires which have been twisted to form strands. The strands are then twisted to form a wire rope. When wire rope has a fibre core, it is normally more flexible but is less resistant to environmental damage. On the other hand, a core which is made of a wire rope strand has higher strength and is more resistant to heat damage. Wire rope slings with steel core are normally used in steel plants.
Steep – It describes a surface with a sharp upward angle or a high rate of change. While there’s no universal definition, steep slopes are often quantified by a slope gradient (angle), which can vary by context but typically exceeds 20-degree to 30-degree or a 20 % to 40 % grade, indicating a substantial vertical rise over horizontal distance. These slopes need careful design and construction to manage stability, water runoff, and erosion.
Steeped construction – In pattern-making, it consists of the courses of material which when fastened together resemble steps.
Steering – It is the control of the direction of motion or the components which enable its control. Steering is achieved through different arrangements.
Stefan–Boltzmann law – It describes the intensity of the thermal radiation emitted by matter in terms of that matter’s temperature. For an ideal absorber / emitter or black body, the Stefan–Boltzmann law states that the total energy radiated per unit surface area per unit time (also known as the radiant exitance) is directly proportional to the fourth power of the black body’s temperature.
Stefan flow – It refers to the weak convective hydrodynamic transport of air caused by a drop in vapour pressure at a condensing surface, which generates a dynamic equilibrium with a lower concentration of water vapour and a higher concentration of dry air. This phenomenon occurs simultaneously with other microphysical processes, particularly under conditions of condensation or evaporation.
Stefan number – It is the ratio of sensible heat to latent heat of bulk slurry, and it is a critical factor influencing the forced convective heat transfer in systems involving phase change materials. A lower Stefan number indicates greater utilization of latent heat.
Stellite – It is a proprietary name of a group of complex alloys retaining their hardness strength and resistance to oxidation at high temperatures. These alloys contain tungsten, cobalt, cobalt, chromium, and carbon.
Stem – It is a component of a valve. It connects the actuator and the disk. It is responsible for positioning the disk. It provides the necessary movement to the disk, plug, or the ball for opening or closing the valve, and is responsible for the proper positioning of the disk. It is connected to the valve handwheel, actuator, or the lever at one end and on the other side to the valve disc. In gate or globe valves, linear motion of the disk is needed to open or close the valve, while in plug, ball and butterfly valves, the disk is rotated to open or close the valve. Stems are normally forged, and connected to the disk by threaded or welded joints or other techniques.
Stem-and-leaf plot – It provides a graphical representation of a set of scores which can be used to examine the shape of the distribution, the range of scores, and where the scores are concentrated. The boxplot, which builds on the information displayed in a stem-and-leaf plot, is more concerned with the symmetry of the distribution and incorporates numerical measures of central tendency and location to study the variability of the scores and the concentration of scores in the tails of the distribution. The boxplot uses the median and quartiles of a distribution. Bedsides quartiles, there are lower quartile and upper quartile.
Stem connector – It is the device which connects the actuator stem to the valve stem.
Stem material – It refers to the specific material used for the stem of a valve, such as a hard alloy like Inconel, chosen for strength and corrosion resistance to withstand actuator and gearbox loads.
Stem packing – It is a sealing material which prevents leaks around the stem (or spindle) of a valve, where it passes through the valve’s bonnet or gland. It creates a tight seal to ensure no fluid or gas escapes when the valve is closed.
Stenciling – It is the process by which lettering or a design through which a substance (ink, paint, or metallic powder) is forced onto a surface to be printed. It is normally used to mark steel fabrications but generally does not remain after the galvanizing process.
Step – It is also called stage. It describes the number of steel cord steps in a conveyor belt splice such as 1-step, or 2-step etc.
Step aging – It is aging of metals at two or more temperatures, by steps, without cooling to room temperature after each step.
Step bearing – It is a plain surface bearing which supports the lower end of a vertical shaft. Other types of bearings can be thus described when they are mounted on a step or bracket.
Step-down converter – It is also known as a buck converter. It is a type of electronic circuit which reduces a higher input direct current voltage to a lower output direct current voltage. It accomplishes this by using a switching action with components like a transistor, inductor, and capacitor to efficiently transfer energy and regulate the voltage level. These converters are essential in several electronic devices and systems which need a lower voltage to operate correctly.
Step-down test – It is a test involving the preparation of a series of machined steps progressing inward from the surface of a bar for the purpose of detecting by visual inspection the internal laminations caused by inclusions segregates.
Step-down transformer – It is a transformer that reduces the voltage of alternating current electricity. It does this by having fewer turns of wire in its secondary winding compared to its primary winding. This means that when alternating current power is applied to the primary winding, it creates a magnetic field that induces a lower voltage in the secondary winding.
Step fracture – It is cleavage fractures which initiate on several parallel cleavage planes.
Step gate – It is a vertical sprue containing a number of side branches or entries at different levels into the casting cavity.
Step-ladder – It is defined as a self-supporting ladder with a hinged frame, wide horizontal steps, and a top platform for carrying tools, designed to be stable when fully opened.
Step nozzle – It is a new technique at sub-entry nozzle (SEN) which has reported to improve the fluid flow pattern and inclusion removal. The flow pattern at out-ports of conventional sub-entry nozzle is uneven or biased because of the sliding gate of sub-entry nozzle. This biased flow pattern (swirl flow at out-ports of sub-entry nozzle) increases the impingement of the jet, and hence worsens inclusion removal to top surface. By using inner annular steps, the biased flow in mould can be weakened. The calculation suggests that the removal fraction of 50 micro-meters inclusions to the top surface of the mould is 2 % with the conventional sub-entry nozzle, but increases to 7 % with the use of the stepped sub-entry nozzle.
Step-out drilling – It consists of holes drilled to intersect a mineralization horizon or structure along strike or down dip.
Stepped beam – It is a structural element whose cross-section changes in one or more places along its length, creating a profile with distinct step-like features, rather than a uniform, continuous shape. This non-prismatic design allows for load distribution, potential weight reduction, and the creation of larger clearances for mechanical systems in high-rise buildings, though analysis needs specific methods to account for the sudden changes in stiffness.
Stepped bearing – It is a thrust bearing in which the working face consists of one or more shallow steps. Bearings of this type have been originally described by Rayleigh. A distinction is to be drawn between a stepped bearing and a step bearing.
Stepped compact – It is a powder metallurgy compact with one (dual step) or more (multistep) abrupt cross-sectional changes, normally got by pressing with split punches, each section of which uses a different pressure and a different rate of compaction.
Stepped extrusion – It refers to a type of extrusion process where the cross-section of the extruded material changes in a stepwise manner, rather than a smooth transition, as the material is forced through a die.
Stepper motor – It is also known as step motor or stepping motor. It is an electric motor which rotates in a series of small angular steps, instead of continuously. Stepper motors are a type of digital actuator. Like other electro-magnetic actuators, these motors convert electric energy into mechanical energy to perform work. A stepper motor is a brushless direct current electric motor which divides a full rotation into a number of equal steps. The motor’s position can be commanded to move and hold at one of these steps without any position sensor for feedback (an open-loop controller), as long as the motor is correctly sized to the application in respect to torque and speed.
Step response – It is the behaviour of a control system in response to an abrupt change of input.
Step-up transformer – It is a device which increases the voltage from its primary winding to its secondary winding, while maintaining the same power and frequency. It effectively converts low voltage and high current to high voltage and low current. This is achieved by having more turns in the secondary winding compared to the primary winding.
Stepwise reaction – It is a reaction which occurs through a series of distinct, individual steps, each involving the breaking and forming of specific bonds, leading to the eventual transformation of reactants into products. These reactions are characterized by the involvement of reaction intermediates, which are species formed in one step and consumed in a subsequent step.
Stereo angle – It is one half of the angle through which the sample is tilted when taking a pair of stereoscopic micrographs. The axis of rotation lies in the plane of the sample.
Stereochemistry It is a sub-discipline of chemistry, studies the spatial arrangement of atoms which form the structure of molecules and their manipulation. The study of stereochemistry focuses on the relationships between stereoisomers, which are defined as having the same molecular formula and sequence of bonded atoms (constitution) but differing in the geometric positioning of the atoms in space. For this reason, it is also called as 3D chemistry. The prefix stereo means ‘three-dimensionality’. Stereochemistry applies to all kinds of compounds and ions, organic and inorganic species alike. Stereochemistry affects biological, physical, and supramolecular chemistry.
Stereographic projection – It is a method to represent three-dimensional orientation data, such as planes and lines, in a two-dimensional format, often on a circular chart called a stereo-net. It maps points from the surface of a sphere onto its equatorial plane from a specific pole, like the south pole. This angle-preserving technique is used in fields like structural geology, crystallography, and mathematics to visualize and analyze complex 3D relationships on a flat surface.
Stereolithography – It is a 3D printing process which builds objects layer by layer using photo-polymerization. It utilizes a liquid resin that is selectively cured by a ultra-violet light source, solidifying it into a solid shape. This process is frequently used for creating intricate and precise models and prototypes.
Stereolithography apparatus (SLA) – It consists of equipment used for computerized building of three-dimensional models and patterns. It enables the data representation of a CAD (computer aided design) solid model to be directly converted into a plastic model of a casting.
Stereolithography process – It is a 3D printing process which builds objects layer by layer by solidifying a liquid photopolymer resin with a computer-controlled ultraviolet (UV) laser. The laser selectively cures, or hardens, the liquid resin, tracing the cross-section of the 3D object’s design as specified in a digital CAD (computer-aided design) file. By repeating this process, creating one thin layer at a time, the full three-dimensional object is built.
Stereophonic sound – It is the sound reproduction systems intended to reproduce sound emanating from more than one direction.
Stereophotogrammetry – It is a method of generating topographic maps of fracture surfaces by the use of a stereoscopic microscope interfaced to a micro-computer which calculates the three-dimensional coordinates of the fracture surface and produces the corresponding profile map, contour plot, or carpet plot.
Stereoscopic microscope – It is also known as stereo microscope or dissecting microscope. It is an optical microscope which provides a three-dimensional (3D) view of a sample. It achieves this by using two separate optical paths with two objectives and eye-pieces, each providing a slightly different angle of view to the left and right eyes. This creates a stereoscopic image, allowing for detailed observation of solid samples with complex surface features.
Stereoscopic micrographs -These are a pair of micrographs (or fractographs) of the same area, but taken from different angles so that the two micrographs when properly mounted and viewed reveal the structures of the objects in their three-dimensional relationships.
Stereoscopic sample holder – It is a sample holder designed for the purpose of making stereoscopic micrographs. It makes possible the tilting of the sample through the stereo angle.
Sterling silver – It is a silver alloy containing at least 92.5 % silver, the remainder being unspecified but normally copper. Sterling silver is used for flat and hollow tableware and for different items of jewelry.
Stern-tube bearing – It is the final bearing through which a propeller shaft passes in a boat or ship.
Stewardship – It refers to the responsible and ethical management of resources entrusted to one’s care, frequently within an organization, to maximize value for stakeholders while adhering to ethical standards. It emphasizes the role of managers and leaders in acting as caretakers, ensuring resources are used wisely and sustainably.
Stewart platform – It is a type of parallel manipulator which has six prismatic actuators, normally hydraulic jacks or electric linear actuators, attached in pairs to three positions on the platform’s base-plate, crossing over to three mounting points on a top plate. All 12 connections are made through universal joints. Devices placed on the top plate can be moved in the six degrees of freedom in which it is possible for a freely-suspended body to move, three linear movements ‘x’, ‘y’. ‘z’ (lateral, longitudinal, and vertical), and the three rotations (pitch, roll, and yaw).
Stick electrode – It is a shop term for covered electrode. It is also known as shielded metal arc welding (SMAW) electrode. It is a consumable metal rod coated with flux, used as both the filler metal and the electrode in the welding process. The flux coating provides shielding gas and slag, protecting the weld from contamination. The arc is formed between the electrode and the base metal, melting both and fusing them together.
Stick electrode welding – It is also known as manual metal arc welding, flux shielded arc welding, or shielded metal arc welding. It is a manual arc welding process which uses a consumable electrode covered with a flux to lay the weld.
Sticker – It is a lump on the surface of a casting caused by a portion of the mould face sticking to the pattern. It is also a forming tool used in moulding.
Sticker breaks – These are arc-shaped coil breaks, normally located near the centre of sheet or strip.
Stickers – Stickers refer to a defect that appears as transverse lines on the surface of the steel strip after it has been uncoiled. These lines are caused by the steel wraps sticking together during the annealing process because of the factors like contaminated emulsion from cold rolling and excessive pressure.
Sticking – It is adherence of foil surfaces sufficient to interfere with the normal ease of unwinding.
Stick out – It is a non-standard term for electrode extension.
Stick-slip – It is a relaxation oscillation normally associated with a decrease in the coefficient of friction as the relative velocity increases. Stick-slip has been originally associated with formation and destruction of interfacial junctions on a microscopic scale. This is frequently the basic cause. The period depends on the velocity and on the elastic characteristics of the system. Stick-slip does not occur if the static friction is equal to or less than the dynamic friction. The motion resulting from stick-slip is sometimes referred to as jerky motion.
Stick-slip motion – It is defined as a phenomenon occurring during sliding motion where the friction force varies substantially, causing intermittent periods of adhesion and sliding between surfaces. This results in fluctuations in sliding velocity and can lead to issues such as wear and mechanical failure in engineering applications.
Stick-slip phenomenon – It is a type of jerky motion which occurs when two surfaces are sliding against each other. It is characterized by alternating periods of adhesion (sticking) and sudden movement (slipping), caused by the difference between static and kinetic friction, where static friction is typically higher than kinetic friction. This results in oscillations of velocity, vibrations, and potentially annoying sounds, and is seen in everyday phenomena like a squeaking door or chalk on a chalk-board.
Stiction – It is a term sometimes which is used to signify the condition in which the frictional resistance is sufficient to prevent macroscopic sliding.
Stiff arc – In welding, a stiff arc refers to an arc with a strong, focused, and forceful nature, frequently associated with deeper penetration into the base metal. It provides a lot of ‘dig’, meaning that it pushes the molten metal into the joint. While it can be beneficial for root passes and achieving deep penetration, it can also result in increased spatter.
Stiffness – It is a measure of modulus. It is the relationship of load and deformation. It is the ratio between the applied stress and resulting strain. It is a term frequently used when the relationship of stress to strain does not conform to the definition of Young’s modulus. It is the rate of stress with respect to strain. The higher is the stress needed to produce a given strain, the stiffer the material is said to be. It is also the ability of a material or shape to resist elastic deflection. For identical shapes, the stiffness is proportional to the modulus of elasticity. For a given material, the stiffness increases with increasing moment of inertia, which is computed from cross-sectional dimensions.
Stiffness tensor – It is also called elasticity tensor. It is a fourth-order tensor which mathematically relates stress and strain in a material, defining its stiffness and elastic response to applied forces. It essentially describes how a material deforms (strain) under an applied load (stress). For linear elastic materials, it can be used to derive the relationship between increments of stress and strain, and its components can vary depending on the material’s symmetry, with isotropic materials having simpler forms.
Stimulus – It is a signal, force, or condition which an engineered system is exposed to, causing a response or change in its behaviour. This input can be internal, like an internal pressure within a system, or external, like a user input or a change in the environment. The system’s response to the stimulus is frequently the focus of analysis and design in engineering. In an environmental context, a stimulus is any detectable change in the surrounding environment that triggers a reaction or response, like a change in temperature or light. These stimuli can be internal or external. The ability to detect and respond to these stimuli is called sensitivity.
Stippled finish – It is a pebbly textured porcelain enamel, frequently multi-coloured.
Stirred media mills – These mills are normally constructed in the form of a cylindrical drum inside which there are a series of rods, arms or perforated discs which are rotated on a central shaft. The drum is loaded with grinding media, such as metal balls or glass sand. The media and the charge are ‘stirred’ together and thus the grinding takes place. These mills are suited mainly for very fine grinding of soft materials. They are normally used with wet grinding but can also be used for dry grinding. Product size is as small as 0.005 millimeters.
Stirrer – It refers to an agitator which is a general type of mechanical device.
Stirrer motor – It is an electric motor which rotates a stirrer shaft and impeller to agitate and mix liquids or other substances in a laboratory, industrial, or domestic setting. It provides controlled rotational motion for achieving different levels of mixing, from gentle blending to high-speed agitation, ensuring uniformity and consistent quality of the final product. Key features frequently include adjustable speed settings, overload protection, and automatic shut-off capabilities for safety and efficiency.
Stirring – It is the process of mixing liquids or other substances by moving them around or agitating them frequently in a circular motion. It is used to achieve homogenization, evenly disperse temperature, and sometimes alter a liquid’s viscosity. In secondary steelmaking, stirring is done with argon gas. Gas stirring can aggravate refractory erosion. Too little stirring leads to superheating of the slag and surface layers of the steel, low heating efficiency, and also increased refractory erosion. Excessive stirring causes metal splashing, short-circuiting, carbon pickup, electrode ‘seeking’ and low heating efficiency. Higher stir rates are typically used to open the eye for alloy additions and desulphurization. Better thermal efficiency and inclusion floatation are normally achieved at lower stirring rates.
Stirring energy – It refers to the mechanical or electro-magnetic energy input used to set a liquid in motion through stirring, which aims to improve mixing, heat transfer, and mass transfer in industrial processes. It is a quantitative measure of the power applied to the fluid, with higher stirring energy normally resulting from higher stirring speeds or stronger electro-magnetic fields, though the exact relationship to process outcomes can be complex and depend on factors like the fluid’s viscosity and the stirrer’s design.
Stir zone (SZ) – It is also called nugget zone. It is the central region of friction stir welding (FSW) or friction stir processing (FSP), where the rotating tool generates intense heat and plastic deformation, resulting in a microstructure of fine, equiaxed grains which are considerably different from the original base material. This process softens the material and mixes it, creating a fine-grained structure and improving material properties without melting.
Stitching – It is a method of three-dimensional (translaminar) reinforcement in which a needle is used to insert a reinforcing thread (normally aramid or glass) through a two-dimensional laminate. Both dry preforms and prepreg laminates have been stitched.
Stochastic – The adjective ‘stochastic’ implies that a process or data generating mechanism involves a random component or components. A statistical model consists of stochastic and deterministic components.
Stochastic behaviour – It refers to the inherent variability in parameters and intrinsic behaviour of components, which includes random noise behaviour, such as thermal noise, and statistical variation from nominal values, affecting the performance of designs.
Stochastic optical reconstruction microscopy (STORM) – It is a super-resolution imaging technique which achieves high-resolution images by sequentially activating and localizing photo-switchable fluorophores over several cycles, creating a super-resolved image from the precise locations of these single fluorescent molecules. This process overcomes the diffraction limit of light, enabling the visualization of biological structures at the nanoscale with high detail.
Stochastic parameter – It is a variable in a model or system which incorporates randomness or uncertainty, meaning its value cannot be precisely known beforehand and is subject to random fluctuations or variability. These parameters are used to represent factors like random price changes, unpredictable customer arrivals, or the inherent uncertainty in factors like wind speed. By incorporating stochastic parameters, models can simulate different possible scenarios and analyze how these uncertainties affect outcomes, which is crucial for decision-making in fields such as finance, engineering, and optimization.
Stochastic search methods – These methods consist of a large group of optimization techniques which utilizes probabilistic methods. Two common methods are genetic algorithms and simulated annealing.
Stock – It is a general term which is used to refer to a supply of metal in any form or shape and also to an individual piece of metal which is formed, forged, or machined to make parts. Stock is also used as a synonym of inventory. It refers to all or the quantity of products which an organization has stored. Both raw materials and finished products can be considered products in stock, provided these materials are stored ready for their entry into production or final sale. It is also a term for unvulcanized, mixed rubber compound. In rolling mills, stock refers to the raw material, like a billet or slab of metal, which is being processed to reduce its thickness and shape. It is the piece of material which the rolling mill shapes into a desired final product.
Stock allowance – It is the material added to a part to allow for surface preparation or precise dimensioning by machining.
Stock bins – Stock bins are storage bins in the stock house in which the furnace charge materials are stored.
Stock cores – These are standard cores of common diameters which are kept ‘in stock’ for general use.
Stock finish – It is a finish of a flange. In this finish, the surface is created by a continuous spiral groove. The roughness of the finish is from 5 micro millimeters to 20 micro millimeters and is cut with a tool with an approximately 1.5 millimeters or larger radius.
Stock house – It is also called warehouse. It is a facility which is used for storing and managing raw materials, components, or finished goods. It is a crucial part of the supply chain, ensuring that materials are readily available for production or distribution. In a blast furnace, it is the place where furnace charge materials are stored, screened, and weighed before sending to the furnace top for charging.
Stock-house bins – Stock-house bins actually consist of a number of conventional bins grouped in an elevated structure for batch delivery of the materials to the process. A blast furnace has such stock-house bins its stock house. The bins are normally filled by belt conveyors. The discharge is through mechanical bin gates either into the skip or onto the conveyor belt.
Stock level – It refers to the quantity of a specific product an organization has in its inventory at a given time, managed to meet customer demand while minimizing costs. Maintaining the right stock level is crucial to avoid stockouts (running out of stock) or over-stocking (holding too much), as both extremes can disrupt operations and impact profitability.
Stock-line diameter – It is the diameter of the blast furnace at the stock-line measured from face to face of the brickwork, embedded armour, or inner face of movable armour.
Stock-line level – For blast furnace with the two-bell top, it is the horizontal line at the bottom of the large bell when closed, e.g., a 2 meters stock-line means the horizontal line located 2 meters below the large bell when closed. For blast furnace with bell less top, it is the horizontal line located 1 meter below the tip of the rotating chute in the vertical (90-degree) position.
Stock management system – It is also known as inventory management system. It is a system which tracks, manages, and maintains inventory levels, aiming to prevent understocking and overstocking. It provides real-time visibility into inventory, including location and condition, and aids in optimizing stock levels to meet demand efficiently.
Stock material – It is an item, raw or processed, kept on hand by an organization for future use in production or sale, contrasting with materials consumed immediately. It encompasses those things, which are tracked in inventory to prevent waste and ensure availability for business operations.
Stock verification – It means to verify that the material is available as per the details, specifications and balance quantity as mentioned in the material register / record. In other words, it is tallying of the up-to-date book balance with the actual physical balance of the material. It is a process of confirming the accuracy and integrity of inventory records stored in an organization’s database.
Stoichiometric compound – It is a chemical compound where the constituent elements are present in fixed, exact ratios, as defined by its chemical formula and conforming to the ‘law of definite proportions’, e.g., water (H2O) always has a fixed 2:1 ratio of hydrogen to oxygen atoms. Compounds which deviate from these exact ratios, frequently because of the defects in their crystal structure, are called non-stoichiometric compounds.
Stoichiometric equation – It is a balanced chemical equation which uses coefficients to represent the quantitative, or numerical, relationships between reactants and products in a chemical reaction. These coefficients establish mole ratios, which serve as conversion factors to determine the exact quantities of substances involved, ensuring the law of conservation of mass is upheld.
Stoichiometric oxidation – It is the complete oxidation of a known quantity of a substance where the quantity of the oxidant is precisely calculated to match the substance’s need as per the reaction’s balanced chemical equation, ensuring that the number of electrons lost in oxidation precisely equals the number of electrons gained in reduction. This concept is used in chemical analysis to correct for inorganic species and ensure accurate measurements, such as in chemical oxygen demand (COD) tests.
Stoichiometry – It is the relationships between the masses of reactants and products before, during, and following chemical reactions. Stoichiometry is founded on the law of conservation of mass where the total mass of the reactants equals the total mass of the products, leading to the insight that the relations between quantities of reactants and products typically form a ratio of positive integers. This means that if the quantities of the separate reactants are known, then the quantity of the product can be calculated. Conversely, if one reactant has a known quantity and the quantity of the products can be empirically determined, then the quantity of the other reactants can also be calculated.
Stoke (centi-stoke) – It is the centimeter-gram-second (cgs) unit of kinematic viscosity.
Stokes equation – It normally refers to Stokes’ Law, a formula describing the drag force on a spherical object moving slowly and steadily through a viscous fluid. In contrast, the term ‘Stokes equation’ can also refer to the more general Navier-Stokes equations, a system of partial differential equations which model the motion of viscous fluids in general, though Stokes himself refined the earlier work of Navier in this area.
Stokes’ law – It gives the frictional force, also called drag force, exerted on spherical objects moving at very small Reynolds numbers in a viscous fluid. It is an expression describing the resisting force on a particle moving through a viscous fluid and showing that a maximum velocity is reached in such cases, e.g., for an object falling under gravity through a fluid.
Stokes number – It is a dimensionless quantity which describes how a particle behaves in a fluid flow, comparing the particle’s characteristic response time to the fluid’s characteristic time. It is the ratio of the particle’s relaxation time to the fluid’s characteristic time. A low Stokes number means the particle closely follows the fluid’s flow, while a high Stokes number indicates the particle’s inertia dominates, causing it to deviate from the fluid streamlines.
Stokes Raman line – It is a Raman line which has a frequency lower than that of the incident mono-chromatic beam.
Stokes’ theorem – It is a theorem about integration of three-dimensional functions. It is much used in analysis of electric fields.
Stoking – It is also called continuous sintering. It is pre-sintering, or sintering, in such manner that the objects are advanced through the furnace at a fixed rate by manual or mechanical means.
Stomata – These are tiny, pore-like openings on the surface of plant leaves and stems that facilitate gas exchange, primarily the intake of carbon di-oxide for photosynthesis and the release of oxygen. They also play a crucial role in transpiration, the process of water vapour release from the plant.
Stone finish – This surface finish is grind-finish. In this type of finish the surface roughness (Ra) is aimed at 0.4 micro-meters. This type of finish makes printing and can making scratches less conspicuous.
Stone mastic asphalt (SMA) – It is a bituminous mixture characterized by gap aggregate gradation, designed to provide high durability, rutting resistance, and skid resistance for heavily trafficked roads. It consists of a high binder content which fills voids between coarse aggregates, improving performance and longevity while reducing maintenance costs over time.
Stool – It is a device used on moulding machine to hold pattern plate or refractory block used to support a crucible in a crucible furnace.
Stooling – It consists of supporting green sand cores in machine moulding while pattern is being withdrawn.
Stool plate – It is a plate on a mould machine on which stools are mounted.
Stop – It is a device for positioning of stock or parts in a die or in a mill.
Stop and dwell motion – Some machines are required to provide either stop and dwell motion or reverse motion. This is achieved by combining non-circular gears with round gears and a differential (epicyclic gear train). Stop and dwell motion is common in indexing mechanisms. Reverse motion is required where a transfer device must operate between two locations.
Stop-band attenuation – It refers to the reduction in signal amplitude within a specific frequency range which a filter is designed to suppress, typically measured in decibels (dB), to minimize unwanted signals or noise in high-speed analog-to-digital conversion applications.
Stop check valve – It is a combination of a lift check valve and a globe valve. It has a stem which, when closed, prevents the disk from coming off the seat and provides a tight seal (similar to a globe valve). When the stem is operated to the open position, the valve operates as a lift check. The stem is not connected to the disk and functions to close the valve tightly or to limit the travel of the valve disk in the open direction. It is like having two valves in one. The internal disc, which is not attached to the stem, performs as a lift check allowing it to freely move up and down when the stem is raised to adjust the opening and closing. This controls the flow rate, but when backflow occurs, the disconnected disc functions as a piston check and quickly closes, thus preventing reverse flow into the boiler. If needed, the stem can be manually lowered for flow to be stopped or completely shut off.
Stopcock – A stopcock is a form of valve used to control the flow of a liquid or gas. The term is not precise and is applied to many different types of valves.
Stope – It is an excavation in a mine from which ore is, or has been, extracted.
Stoping – It is the underground process of excavating ore, creating large open spaces called stopes. This technique is used when the surrounding rock is strong enough to remain stable, or with artificial support, to remove the valuable mineral from an ore body. Several methods exist, such as open stoping and cut-and-fill mining, with the choice depending on the ore body’s geology, rock strength, and economic factors.
Stop mark – It is a transverse peripheral ridge on a product arising from a stoppage during rolling, extrusion or drawing.
Stop-off – It is a material which is used on the surfaces adjacent to the joint to limit the spread of soldering or brazing filler metal. In foundry, it means to shorten or change a mould.
Stop-off strip – It is the reinforcing members on frail patterns. Impressions later filled with sand.
Stopper head – It is a rounded refractory shape, normally made from clay and graphite, providing a valve head seating into a nozzle brick, this assembly forming a metal flow control for bottom-pouring ladles.
Stopper rod – It is a device in a bottom-pour ladle for controlling the flow of metal through the nozzle into a mould. The stopper rod consists of a steel rod, protective refractory sleeves, and a graphite stopper head.
Stopping off – It means applying of a resist. It also means depositing a metal (e.g., copper) in localized areas to prevent carburization, decarburization, or nitriding in those areas. It is also filling in a portion of a mould cavity to keep out molten metal. It is the application of a resist to any part of an electrode namely cathode, anode, or plating rack. It is depositing a metal (copper, for example) in localized areas to prevent carburization, decarburization, or nitriding in those areas.
Stops – These consist of metal pieces inserted between die halves. Stops are used to control the thickness of a press-moulded part. It is not a desired practice, since the resin receives less pressure, which can result in voids.
Stopwatch – It is a timing device which can be mechanical or digital, used to measure short or long durations of time, and can include features such as split hands for recording elapsed time.
Storage – It is the area where finished products are stacked for pick-up or delivery.
Storage area – It is a specific space, location, or facility designated for temporarily holding or keeping items meant for storage. The purpose of a storage area is to provide a designated, frequently organized, place to put things in store, whether it’s a dedicated room for storing inventory items or a secure section for sensitive materials.
Storage life – It is the period of time during which a liquid resin, packaged adhesive, or prepreg can be stored under specified temperature conditions and remain suitable for use. It is also called shelf life.
Storage loss – It refers to the reduction in the quantity or quality of goods because of the deterioration, spoilage, theft, or other causes during the storage period. It can manifest as a physical loss of substance (quantitative loss) or a decrease in quality or usability (qualitative loss). Normal causes include environmental factors such as moisture and temperature.
Storage modulus – It is a quantitative measure of elastic properties in polymers, defined as the ratio of the stress, in phase with the strain, to the magnitude of the strain. The storage modulus can be measured in tension, flexure, compression, or shear.
Storage of carbon di-oxide – It refers to the injection of anthropogenic carbon di-oxide into deep underground rock formations, facilitating its permanent removal from the atmosphere. This process utilizes geological reservoirs with porous rocks which allow for the efficient storage and movement of carbon di-oxide, typically at depths of 800 meters or more.
Storage stability – It is a measure of the ability of a lubricant to undergo prolonged periods of storage without showing any adverse conditions because of oxidation, oil separation, contamination, or any type of deterioration.
Storage tube – It is a type of cathode ray tube which is used for storing images or data.
Storage yard – It is an open area which is used to store several materials, equipment, or vehicles outside an enclosed building, whether for temporary or permanent use. These yards are frequently used for storing construction materials, equipment, vehicles, or other goods. They can also function as a temporary buffer for inbound and outbound containers in container terminals.
Store – It is an important component of material management since it is a place that keeps the materials in a way by which the materials are well accounted for, are maintained safe, and are available at the time of requirement. Storage is an essential and most vital part of the economic cycle and store management is a specialized function, which can contribute significantly to the overall efficiency and effectiveness of the materials function. Literally store refers to the place where materials are kept under custody. Typically, a store has a few processes and a space for storage. The main processes of store are (i) to receive the incoming materials (receiving), (ii) to keep the materials as long as they are required for use (keeping in custody), and (iii) to move them out of store for use (issuing). The auxiliary process of store is the stock control also known as inventory control. In a manufacturing organization, this process of receiving, keeping in custody, and issuing forms a cyclic process which runs on a continuous basis. The organizational set up of the store depends upon the requirements of the organization and is to be tailor made to meet the specific needs of the organization.
Stored elastic energy – It is also called elastic potential energy. It is the energy held within an elastic object as a result of it being deformed by stretching, compressing, or twisting. This stored energy is released when the object returns to its original shape, converting into other forms of energy like kinetic or sound energy. Examples are a stretched rubber band and a compressed spring.
Storekeeper – Storekeeper is a person who manages and maintains a storage facility, responsible for receiving, storing, and distributing inventory, as well as maintaining accurate records, ensuring stock availability, and overseeing the overall organization and safety of the store or warehouse. Key duties include inventory management, receiving and inspecting deliveries, organizing stock using methods like first-in, first-out (FIFO), managing logistics, maintaining a clean and safe environment, and potentially supervising other store emploees.
Storekeeping – It relates to safe custody and preservation of the materials stocked, to their receipts, issue and accounting. The objective is to efficiently and economically provide the right materials at the time when it is required and in the condition in which it is required. The basic job of the store is to receive the materials and act as a caretaker of the materials and issue them as and when they are needed for the activity of the organization. Once the material has been received and cleared through inspection and accepted for use, it needs safe custody of the stores. The role of custody is to receive and preserve the material. A stage comes when the material is needed for use. Store at that time releases the material from its custody to the user department and the process is called ‘issue of goods. It might also happen that after partial use, some materials having useable value in future are returned to the store and thus they also become part of the custody again. Storekeeping activity does not add any value to the materials. In fact, it adds only to the cost. The organization is to spend money on space (expenditure on land, building passage and roads), machinery (store equipment), facilities (e.g., water, electricity, communication etc.), personnel, insurance, maintenance of store equipment, and stationary etc. All of these get added to the organizational overheads and finally get reflected in the costing of the finished product. However, it is an essential function in any organization.
Storey – It is any level part of a building with a floor which can be used by people for different purposes.
Storm – It is a disturbed state of an astronomical body’s atmosphere, especially affecting its surface, and strongly implying severe weather. It can be marked by strong wind, thunder and lightning (a thunder-storm), heavy precipitation, such as ice (ice storm) or wind transporting some substance through the atmosphere (as in a dust storm, snow-storm, and hail-storm etc.). Storms normally cause significant negative impacts to lives and property, such as storm surge, heavy rains, lightning, wildfires and vertical wind shear which can cause airplane crashes.
Storm drain – It is infrastructure designed to drain excess rain and ground water from impervious surfaces such as paved streets, car parks, parking lots, footpaths, sidewalks, and roofs. Storm drains vary in design from small residential dry wells to large municipal systems.
Storm-water – It is the water discharged from a surface as a result of rainfall or snowfall.
Storm-water drainage system – It is a structure for collecting, storing, or disposing of stormwater and the connections between them. The system includes stormwater sewers, pumping stations, storage areas, management facilities, treatment facilities, and outfall structures.
Stoves – These are used for heating the air blast for the blast furnace. They are constructed with checkers bricks. Normally three or four stoves are there for a blast furnace. They work as a counter-current regenerative heat exchangers.
Stradle milling – It consists of face milling a work-piece on both sides at once using two cutters spaced as needed.
Straight bevel gear – It is the simplest type of bevel gear, characterized by teeth which are cut straight across the face of the gear. They are normally used for applications with peripheral speeds up to 300 meters per minute where utmost quietness and smoothness are not critical.
Straight-blade shearing – In it, the flat work-piece is placed between a stationary lower blade and a movable upper blade. As the upper blade is forced downward, it cuts the metal into two parts. Straight-blade shearing is the most economical method of cutting straight-sided blanks from flat sheet, strip, and plate with thickness no more than 50 millimetres (mm). The process is also widely used for cutting sheet into blanks which are subsequently to be formed or drawn. Since shear gauging can be set within + 0.13 millimetres, the shearing process is normally limited to + 0.4 millimetres tolerances in 1.6 millimetres thick material.
Straight crack – It is a crack whose path maintains a linear trajectory, characterized by minimal deviation from its original orientation, particularly under conditions of stress where stability is assessed by the ratio of its displacement to its original length.
Straighteners – Straighteners are used for giving the rolled product certain specified degree of straightness. Several types of straightening machines are used and they are broadly classified in three groups. These are (i) cross-roll straighteners, (ii) section straighteners, and (iii) stretch straighteners. This categorization is based on the basic principles on which they operate. In the first two categories of straightening machines, the rolled product is made to pass through a set of staggered rolls, producing reverse kinematic loading of the rolled product, resulting in redistribution of the plastic strains, which secures the desired straightening. Multi line straighteners are used at high productivity rates. The concept is to straighten cooling bed lengths in order to have less feeding operations and better utilization of the straightening roll drives. Proper alignment and centering of the bars under the rolls is essential. The recent improvements in this area are (i) use of automatic section feeding to the straighteners, (ii) quick change of roll sets mounted on a stand by carriage, motorized roll gap arrangement, and (iv) the whole unit is mounted on a platform that can be shifted out of the line for maintenance without stopping mill production.
Straightening – It is the bending, twisting, or stretching operation to correct any deviation from straightness in bars, tubes, or similar long parts or shapes. This deviation can be expressed as either camber (deviation from a straight line) or as total indicator reading (TIR) per unit of length. It is a finishing operation for correcting misalignment in a forging or between different various sections of a forging.
Straight link chains -These chains have alternate ‘outside’ and ‘inside’ links. These include chains with rollers and chains which are similar to chains with rollers, but are roller-less.
Straightness – It is a form control that ensures a feature’s lines are within a specified tolerance of a true straight line. It is a 2-dimensional tolerance which can be applied to surfaces or axes. When applied to a surface, it controls the variance of lines within that surface, ensuring they remain straight. When applied to an axis, it controls the permissible curvature of the part’s axis.
Straightening machines – These machines fall into two basic categories. The first category of straightening machines is more common and is known as straighteners or flatteners. This arrangement is normally available in machines with between 5 work rollers and 11 work rollers. The roller diameters and centre distances vary depending on material thickness and width but straighteners and flatteners are normally distinguished by fairly large diameter, widely spaced rollers, usually not backed up. The second category of straightening machines is known as a ‘precision leveller’. Precision levellers are distinguished by small diameter closely spaced rollers with backups and the ability to flex those rollers. These machines normally have a far greater number of work rollers than do conventional straighteners. Since these machines work on the material much harder and their rollers can be flexed, precision levellers are used to remove camber, wavy edges, centre buckles, as well as trapped stresses within the material so that it stays flat. Levellers require drives with higher power than straighteners because of the greater amount of work being done to the material.
Straight line – It is a one-dimensional geometric object which is the shortest distance between two points and extends infinitely in both directions without any curvature or breadth. It can be thought of as a continuous series of points traveling in a constant direction, creating a path which never bends or curves.
Straightness – It is the absence of divergence from a right (straight) line in the direction of measurement.
Straight polarity – The preferred term direct current electrode negative (DCEN). It is the arrangement of direct current arc welding leads in which the work is the positive pole and the electrode is the negative pole of the welding arc.
Straight-running steel flat-top chain – It consists of a series of steel top plates with hinge-like barrels curled on each side. Pins are inserted through the barrels to make a joint. Pins are retained by press fits or heading in the barrels of one top plate and are free to articulate in the barrels of the next link. Hence. a continuous length of flat-top chain is formed. The joints in straight-running chain permit flexing in only one plane. The barrels mesh with the teeth of a sprocket to drive the conveyor. As straight-running chains operate, material is worn off the top plates and wear strips, and the top plates get thinner and weaker. As this type of wear progresses, the chain may start to malfunction or it may break.
Straight tooth bevel gears – These gears, also known as plain bevels, have teeth cut straight across the face of the gear. They are subject to much of the same operating conditions as spur gears in that straight tooth bevels are efficient but somewhat noisy. They produce thrust loads in a direction that tends to separate the gears.
Straight warp – It is normally made of high tenacity polyester yarns for the warp and polyamide yarns for the weft, both held together by binder yarns. The warp (lengthwise) yarns are essentially uncrimped.
Strain – It is a measure of the change in size or shape of a body under stress, referred to its original size or shape. Tensile or compressive strain is the change, because of force, per unit of length in an original linear dimension in the direction of the applied force. It is the unit of change in the size or shape of a body because of force. It is also known as nominal strain. The term is also used in a broader sense to denote a dimensionless number which characterizes the change in dimensions of an object during a deformation or flow process.
Strain-age embrittlement – It is a loss in ductility accompanied by an increase in hardness and strength which occurs when low-carbon steel (especially rimmed or capped steel) is aged following plastic deformation. It occurs principally in low-carbon and medium-carbon steels which have not been aluminum deoxidized. Embrittlement occurs for cold-worked materials which are subsequently heated to temperatures between room temperature and 300 deg C. The degree of embrittlement is a function of aging time and temperature, occurring in a matter of minutes at around 200 deg C but needing a few hours to a year at room temperature. The degradation which results is presumed to be because of nitrogen contents that exceed 0.009 %. There is likely a secondary embrittling effect because of the carbon. Strain-age embrittlement results in transgranular fracture. Its presence can be detected by a return of the yield point or a displacement of an indexed transition temperature to higher temperatures in an impact pendulum test.
Strain aging – It is the aging following plastic deformation. It also consists of the changes in ductility, hardness, yield point, and tensile strength which occur when a metal or alloy that has been cold worked is stored for some time. In steel, strain aging is characterized by a loss of ductility and a corresponding increase in hardness, yield point, and tensile strength.
Strain analysis – It is the study of how materials change in shape or size (deform) under applied forces or internal stresses, determining the quantitative aspects of this deformation. It quantifies deformation as a ratio of the change in length to the original length, or the change in angle, helping to understand a material’s response to external loads and predict potential failures or structural integrity.
Strain, axial – It is the linear strain in a plane parallel to the longitudinal axis of the sample.
Strain behaviour – It is a material’s characteristic response, or deformation, to an applied force (stress). It describes the fractional change in an object’s dimensions relative to its original dimensions and is quantified by relating stress to strain through experiments, such as a stress-strain curve. Understanding strain behaviour is vital in engineering to predict how materials behave under different loads and to design structures which can withstand those loads.
Strained casting – It is a phrase used to describe the result when molten metal is poured into the mould at too fast a rate or under too great metallostatic pressure, causing the cope to rise slightly from the drag and resulting in an oversize casting.
Strain data – It refers to information about the quantity of deformation or distortion an object undergoes in response to an applied force or stress, expressed as a ratio of the change in dimension (e.g., length) to the original dimension. This data is quantified by measuring strain, a dimension-less quantity which can indicate tensile (elongation), compressive (contraction), or shear (angular) deformation. Strain data is gathered using instruments like strain gauges to understand material behaviour, structural integrity, and potential failure under load.
Strained heterostructures – These refer to semiconductor structures where strain affects the alignment of band lineups, influencing their electronic properties.
Strain energy – It is the potential energy stored in a body by virtue of elastic deformation, equal to the work which is to be done to produce this deformation.
Strain energy density – It is the strain energy stored in a material per unit volume. It is calculated by dividing the total strain energy by the volume of the material and represents the energy needed to deform a unit volume of a solid. This quantity is frequently visualized as the area under the stress-strain curve up to a certain point of loading, and it provides insight into a material’s resistance to deformation and potential for yielding.
Strain energy release rate – It is the elastic energy per unit of new separation area which is made available at the front of an ideal crack in an elastic solid during a virtual increment of forward crack extension.
Strainer – It is a device which removes solid particles from a flowing liquid or gas, protecting downstream equipment from damage. It is a device, such as a filter, to retain solid particles allowing a liquid to pass. It functions by allowing the fluid to pass through a perforated or mesh straining element, trapping unwanted debris like sediment, rust, and pipe scale. Strainers are crucial for maintaining system efficiency and preventing costly repairs.
Strainer core – It is a perforated core placed at the bottom of a sprue or in other locations in the grating system to control the flow of the molten metal. To some extent, it prevents coarse particles of slag and dross from entering the mould cavity.
Strain etching – It is the metallographic etching that provides information on deformed and undeformed areas if present side by side. In strained areas, more compounds are precipitated.
Strain field – It is the continuous spatial distribution of strain, or deformation, throughout a material or body at a given moment. It is a tensor field which assigns a strain tensor (a mathematical description of deformation) to each point within the material, showing how much and in what direction the material is deforming in response to forces. Strain fields are used to understand and map how materials deform, which can help in structural health monitoring and predicting material failure.
Strain gauge – It is a sensor used to measure the strain or deformation of an object under external forces. It is a device that changes its electrical resistance when subjected to mechanical strain, allowing the quantification of stress experienced by a material.
Strain gradient – It is the rate at which the strain (deformation) changes over a given length or distance within a material. It describes how strain varies spatially, unlike traditional strain which measures overall deformation. As an example, a beam in bending has a strain gradient since the strain is highest at the edges and zero at the centre, while a beam in simple tension has no strain gradient. This concept is particularly important material in the fields of strain gradient plasticity and strain gradient theory to explain size-dependent properties and behaviours at microscopic scales.
Strain hardening – It is an increase in hardness and strength of metals caused by plastic deformation at temperatures below the recrystallization range. It is the modification of a metal structure by cold working resulting in an increase in strength and hardness with loss of ductility. It is also known as work hardening.
Strain-hardening coefficient – It is also known as strain-hardening exponent. It is the value of ‘n’ in the relationship S = K x E to the power ‘n’, where is the true stress, is the true strain, and ‘K’, which is called the strength coefficient, is equal to the true stress at a true strain of 1. The strain-hardening exponent, also called ‘n-value’, is equal to the slope of the true stress / true strain curve up to maximum load, when plotted on log-log coordinates. The n-value relates to the ability of as sheet metal to be stretched in metal-working operations. The higher is the n-value, the better is the formability (stretchability).
Strain-hardening exponent (n-value) – It is also known as strain-hardening coefficient.
Strain hardening rate – It is a quantitative measure of how quickly a material’s strength and hardness increase because of plastic deformation, specifically how the rate of strength increase (or flow stress) changes with increasing true strain. It is frequently represented by the slope of the true stress-true strain curve in the plastic deformation region after the yield point. A higher strain hardening rate means the material needs considerably tly more stress to achieve further plastic deformation as it becomes stronger.
Strain, initial – It is the strain produced in a sample by given loading conditions before creep occurs.
Strain limit – It is a critical value of plastic strain which a material or structure is designed to withstand before permanent failure. It serves as a maximum allowable deformation in engineering contexts, such as pipeline design, to prevent fracture and ensure safety by limiting irreversible shape changes or material damage. This limit is determined from material properties and frequently includes a safety factor to account for real-world conditions and variations.
Strain localizations – It is a generic name used for any plastic instability. These defects are both of process related origin and metallurgical origin. Strain localizations can be both microscopic as well as macroscopic. These can be identified through clear patterns of localized plastic flow and / or as distinct dislocation substructure. These are often responsible for the initiation of micro-cracks, ultimately leading to fracture. These are considered as deformation heterogeneities or plastic instabilities and the instability criteria can be used to describe the formation of strain localizations. For example, a suitable instability criterion is also used in identifying the safe process regimes in a processing map. The criterion can be formulated either from localized deformation or from softening. A much-cited example of the latter is the so-called Dillamore’s criteria. The criteria are simple in its approach and have been successfully used in describing the macroscopic angles of shear bands and also in describing their preferred appearance at certain orientation(s).
Strain markings – These are manifestations of prior plastic deformation visible after etching of a metallographic section. These markings may be referred to as slip strain markings, twin strain markings, and so on, to indicate the specific deformation mechanism of which they are a manifestation.
Strain range partitioning (SRP) – It is a method of dividing the total inelastic strain range experienced during cyclic loading into four components based on the direction of straining (tension or compression) and the type of strain (creep or time-independent plasticity). This approach helps in understanding and predicting the fatigue behavior of materials under complex loading conditions.
Strain rate – It is the time rate of straining for the normal tensile test. Strain as measured directly on the sample gauge length is used for determining strain rate. Since strain is dimensionless, the unit of strain rate is reciprocal time.
Strain-rate hardening – It is also known as dynamic hardening. It is the increase in flow stress with an increase in strain rate. It refers to the phenomenon where a material’s resistance to deformation increases as the rate of strain (deformation) increases. This means that a material under high strain rates needs more stress to deform than it would at lower strain rates.
Strain rate increase – It refer to a condition where the rate of deformation in a material rises, activating dislocation slip and twinning, which intensifies structure refinement and improves deformation heating.
Strain-rate sensitivity (m-value) – It quantifies a material’s tendency to creep and describes how much its flow stress changes with variations in strain rate during plastic deformation. It is the increase in stress (s) needed to cause a certain increase in plastic strain rate (e’) at a given level of plastic strain (e) and a given temperature (T). Strain-rate sensitivity = m =[(delta log s)/ (delta log e’)]eT.
Strain relaxation – It is the reduction in internal strain over time. In it, similar molecular processes occur as in creep, except that the body is constrained.
Strain relief – It is a mechanical apparatus or contrivance deployed to alleviate tension and forestall excessive stress on electrical cables within the conveyor system. Regular inspections stand as a protective measure, ensuring proper strain relief mechanisms are in place to avert cable damage.
Strain, residual – It is the strain associated with residual stress.
Strain rods – These are rods sometimes used on gap frame metal forming presses to lessen the frame deflection. These are also rods which are used to measure elastic strain and hence stresses, in frames of metal forming presses.
Strains, casting – These are the strains produced by internal stresses, resulting from unequal contraction of the metal as the casting cools.
Strain sensitivity – It describes how an output signal (like from a sensor) changes in response to a given strain, often quantified as the ratio of output change to strain change. For a strain gauge, this is represented by the gauge factor, which relates the relative change in electrical resistance (ΔR/R₀) to the applied strain (ε) using the formula ΔR/R₀ = kε, where ‘k’ is the strain sensitivity.
Strain, shear – It is the tangent of the angular change, caused by a force between two lines originally perpendicular to each other through a point in a body. It is also called angular strain.
Strain softening – It is the decrease in flow stress with strain, as during dynamic recrystallization.
Strain state – It is a complete description of the deformation within a homogeneously deformed volume or at a point. The description needs, in general, the knowledge of the independent components of strain.
Strain tensor – It is a mathematical representation to quantify the deformation of a continuous material at a specific point, describing both changes in length (linear strain) and changes in angles (shear strain) of the material in response to forces. It is a symmetric tensor which captures all aspects of deformation, allowing for the calculation of stress and displacement relationships within the material.
Strain, transverse – It is the linear strain in a plane perpendicular to the loading axis of a sample.
Strain, true – It is the natural logarithm of the ratio of gauge length at the moment of observation to the original gauge length for a body subjected to an axial force.
Strand – A strand of wire is several lengths of wire wrapped around a single wire which serves as the ‘core’ of the strand. A strand can have multiple layers of wire which wrap around each other, but the constituent parts of a strand are always going to be solid lengths of wire. 1×7 strand is two layers and is made of seven wires; 1×19 is three layers and is made of nineteen wires. In composites, strand is normally an untwisted bundle or assembly of continuous filaments used as a unit, including slivers, tows, ends, yarn, and so on. Sometimes a single fibre or filament is called a strand.
Strand casting – It is a generic term describing continuous casting of one or more elongated shapes such as billets, blooms, or slabs, if two or more shapes are cast simultaneously, they are frequently of identical cross-section.
Strand containment – The containment region is an integral part of the secondary cooling area. A series of retaining rolls contain the strand, extending across opposite strand faces. Edge roll containment can also be needed. The focus here is to provide strand guidance and containment until the solidifying shell is self-supporting. In order to avoid compromises in product quality, careful consideration is needed to be given to minimize stresses associated with the roller arrangement and strand unbending. Hence, roll layout, including spacing and roll diameters are to be carefully selected to minimize between roll bulging and liquid / solid interface strains. Strand support needs maintaining strand shape, as the strand itself is a solidifying shell containing a liquid core which possesses bulging ferro-static forces from head pressure related to machine height. The area of greatest concern is high up in the machine. Here, the bulging force is relatively small, but the shell is thinner and at its weakest. To compensate for this inherent weakness and avoid shell rupturing and resulting liquid steel breakouts, the roll diameter is small with tight spacing. Just below the mould all four faces are typically supported, with only the broad faces supported at regions lower in the machine.
Strand count – It is the number of strands in a plied yarn. It is the number of strands in a roving.
Stranded cable – It is an electrical cable which consists of multiple, thinner metal wires, known as strands, twisted or bundled together to form a single, larger conductor. This construction provides significantly more flexibility than a solid conductor of the same size, making stranded cables ideal for applications involving movement, such as patch cords, extension cords, or power transmission lines.
Stranded electrode – It is a composite filler metal electrode consisting of stranded wires which can mechanically enclose materials to improve properties, stabilize the arc, or provide shielding.
Stranded wire – It consists of multiple thin metal strands twisted together to form a single, more flexible conductor, unlike solid wire which has a single, solid core. This construction makes stranded wire ideal for applications needing repeated bending or movement, such as power cords for electronics, vehicles, and industrial machinery, since it resists breaking and fatigue.
Strand electro-magnetic stirring (S-EMS) – It refers to using electro-magnetic forces to stir liquid steel within a continuous casting strand. This technique, primarily installed in the secondary cooling zone of a continuous casting machine aims to improve the internal quality of the solidified steel and enhance productivity by promoting a more uniform structure and reducing defects like inclusions and surface cracking.
Strand integrity – It is the degree to which the individual filaments making up the strand or end are held together by the applied sizing.
Strands – Strands of the wire rope consist of two or more wires arranged and twisted in a specific arrangement. The individual strands are then laid in a helical pattern around the core of the wire rope. Strands made of larger diameter wires are more resistant to abrasion, while strands made of smaller diameter wires are more flexible. Strands are designed with various combinations of wires and wire sizes to produce the desired resistance to fatigue and abrasion. Normally, a small number of large wires are more abrasion resistant and less fatigue resistant than a large number of small wires. The required numbers of suitably fabricated strands are laid symmetrical with a definite length of lay around a core to form the finished wire rope.
Strand straightening forces – In continuous casting machines, as unbending occurs, the solid shell outer radius is under tension, while the inner radius is under compression. The resulting strain is dictated by the arc radius along with the mechanical properties of the cast steel grade. If the strain along the outer radius is excessive, cracks can occur, seriously affecting the quality of the steel. These strains are typically minimized by incorporating a multi-point unbending process, in which the radii become progressively larger in order to gradually straighten the product into the horizontal plane.
Strand tensile test – It is a tensile test of a single resin-impregnated strand of any fibre.
Strand wrapped over a drum – It means wrapping of a wire rope on a large cylindrical barrel called drum for storage purposes.
Strap joint – It is a mechanical or structural connection which uses one or more metal plates, called straps, to join two or more components, typically by riveting or bonding. The straps are applied to the components to reduce stress, bending, and other forces, and double-strap designs are frequently preferred over single-strap configurations for higher strength.
Strapping machines – These machines are used for coils, bundles, and piles. These machines are designed for continuous operation. These machines are pneumatically operated and use commercial steel straps of different available width. Strapping can be carried out either by clamping or welding.
Strata – In sampling, it consists of segments of a lot which can vary with respect to the property under study.
Strata method – The strata method needs a luffing and slewing stacker. In the strata stacking method, the stockpile is built up in inclined layers. The stacker builds the first layer travelling along the length of the storage area with its boom at a low elevation. The stacker then moves towards the stockpile centre in pre-set steps while gradually lifting the boom. The result is superimposed inclined layers, matching the angle of repose of the bulk material and providing a good blending as the reclaimer cuts into each of the many layers.
Strategy – It is a perspective, position, or plan developed and undertaken to achieve goals. It is the bridge between policy and concrete actions which outlines how a policy is implemented to achieve its goals. Strategy is a complex concept which involves several different processes and activities within the organization. It involves goals and objectives which the organization needs to achieve to be successful in the market-place. The development of these goals, however, needs a strategic management process to be done correctly and thoroughly.
Strategic business unit (SBU) – In business strategic management, it is a profit centre which focuses on product offering and market segment. Strategic business units typically have a discrete marketing plan, analysis of competition, and marketing campaign, even though they can be part of a larger organizational entity.
Strategic decision-making – It is the process of choosing significant actions which align an organization’s activities with its long-term goals and vision. It involves making high-impact choices based on the analysis of both internal factors (like organizational strengths and resources) and external factors (like market trends and risks) to gain a competitive advantage and ensure sustainable growth. Unlike routine or operational choices, strategic decisions are forward-looking, resource-intensive, and typically made by top management to guide the entire organizational direction over time.
Strategic decisions – These are the decisions which are concerned with whole environment in which the organization operates, the entire resources, and the people who form the organization and the interface between the two.
Strategic management – It is defined today as the art and science of formulating, implementing, and evaluating cross-functional decisions which enable the organization to achieve its objectives. As this definition implies, strategic management focuses on integrating management, marketing, finance, accounting, production, operations, research and development, and information systems for achieving the organizational success. The term strategic management is used sometimes synonymously with the term strategic planning. The latter term is more frequently used in the commercial organizations, whereas the former is frequently used in the corporate organizations. Sometimes the term strategic management is used to refer to strategy formulation, implementation, and evaluation, with strategic planning referring only to strategy formulation.
Strategic material – It is a sort of raw material which is important to an individual’s or organization’s strategic plan and supply chain management. Lack of supply of strategic materials cam leave an organization or government vulnerable to disruption of the manufacturing of products which need those materials. In government terms, if consists of materials, normally raw materials which have a particular strategic significance to the nation, frequently in time of war. Their strategic need is because of their crucial importance for either economic or military purposes. Some materials are relatively simple, but are needed in large quantities during wartime. Others are obscure and technically complex. Although not required in large quantities, their irreplaceability and critical need makes them especially valuable.
Strategic planning – It is the continuous process of making present managerial (risk-taking) decisions systematically and with the greatest knowledge of their futurity, organizing systematically the efforts needed to carry out these decisions, and measuring the results of these decisions against the expectations through organized, systematic feedback.
Stratification – It is the non-homogeneity existing transversely in a gas stream. It refers to the separation of a fluid or substance into distinct layers, typically based on density or temperature differences. This can be a natural phenomenon or a designed feature for specific applications like thermal energy storage. In statistics, stratification is defined as the act of sorting data, people, and objects into distinct groups or layers. It is the division of a population into parts, known as strata stratified random sampling. It is a method of sampling from a population whereby the population is divided into parts, known as strata, especially for the purpose of drawing a sample, and then assigned proportions of the sample are then sampled from each stratum. The process of stratification is undertaken in order to reduce the variability of stratification statistics. In other words, strata are normally selected such that inter-strata variability is maximized, and intra-strata variability is small. When stratified sampling is performed as desired, estimates of strata statistics are more precise than the same estimates computed on a simple random sample. Stratification is a technique used in combination with other data analysis tools. When data from a variety of sources or categories have been lumped together, the meaning of the data can be difficult to see. This data collection and analysis technique separates the data so that patterns can be seen and is considered one of the seven basic quality tools.
Stratification strategy – It involves dividing complex systems, populations, or processes into smaller, more manageable, and homogenous subgroups (strata) to improve analysis, design, or control. This is done by applying stratification to address issues like thermal stratification in heating ventilation and air conditioning systems, stratified sampling in data analysis to improve representativeness, and stratified approaches in evolutionary algorithms to optimize complex problems.
Stratified flow – It is a type of flow in which gas and liquid move separately with a distinct and relatively smooth interface, typically with gas flowing in the upper part and liquid in the lower part of a pipe.
Stratified sampling – It is the process of dividing a population into sub-populations based on shared characteristics to eliminate bias, ensuring that different segments are represented in the sample. This method involves randomly sampling from these sub-populations to prevent any single characteristic from dominating the results.
Stratigraphy – Strictly, it is the description of bedded rock sequences. It is used loosely, the sequence of bedded rocks in a particular area.
Stratosphere – It is the second layer of earth’s atmosphere, located above the troposphere and below the mesosphere, extending from roughly 10 kilometers to 50 kilometers above the surface. This layer is characterized by a stable temperature profile where temperature normally increases with height because of the absorption of ultraviolet radiation by the ozone layer. The ozone layer, a concentrated band of ozone molecules, is a key feature of the stratosphere and plays a crucial role in absorbing harmful solar ultraviolet radiation.
Stratospheric aerosol injection (SAI) – It is a proposed geo-engineering method which involves releasing aerosols into the lower stratosphere to reflect sunlight and cool the earth, mimicking the cooling effects of volcanic eruptions. Engineering aspects focus on developing and testing different delivery systems, such as specialized aircraft, balloons, and hoses, to effectively and safely deploy aerosol precursors like sulphur di-oxide (SO2) or sulphuric acid (H2SO4) into the stratosphere. The engineering challenges include designing vehicles which can operate in the low-density, low-pressure stratospheric environment and developing methods to ensure the aerosols are formed and distributed correctly to achieve the desired climate impact while mitigating potential negative side effects.
Stratospheric ozone – It is frequently referred to as the ozone layer. It is a naturally occurring region in earth’s stratosphere which absorbs majority of the sun’s harmful ultraviolet (UV) radiation, particularly ultraviolet-B radiation (UV-B). This layer, mainly found between 15 kilometers and 35 kilometers above the earth’s surface, acts as a protective shield, preventing majority of the sun’s ultraviolet radiation from reaching the earth’s surface.
Stratospheric ozone depletion – It is the thinning or destruction of the ozone layer in the earth’s stratosphere, mainly caused by man-made chemicals like chloro-fluoro-carbons (CFCs), which contain chlorine and bromine atoms that catalytically destroy ozone molecules. This depletion allows harmful ultraviolet-B (UV-B) radiation to reach the earth’s surface, posing risks to human health, eco-systems, and materials.
Stray capacitance – It is also known as parasitic capacitance. It is the unintended and unavoidable capacitance which forms between two conductors separated by a dielectric (like air or insulation) because of their physical proximity in an electronic circuit or component. This unintentional capacitance can interfere with a circuit’s intended function, especially at high frequencies, by storing energy, altering current flow, and causing measurement errors. It is a property of every conductor, when considered as a non-ideality.
Stray current – It is the current flowing through paths other than the intended circuit. It is also the current flowing in electro-deposition by way of an unplanned and undesired bipolar electrode which can be the tank itself or a poorly connected electrode.
Stray-current corrosion – It is the corrosion resulting from direct current flow through paths other than the intended circuit, e.g., by an extraneous current in the earth.
Streak – It is a diagnostic characteristic of minerals, where scratching a sample on a piece of unglazed porcelain leaves powder of a characteristic colour.
Streak, bearing – It is a longitudinal discolouration which can occur where there are large changes in wall thickness as a result of uneven cooling. These streaks normally appear lighter than the surrounding metal.
Streak, bright – It is a bright superficial band or elongated mark which produces a non-uniform surface appearance.
Streak, buff – It is a dull, continuous streak caused by smudge build-up on a buff used at shearing or other operations.
Streak burnish – It is a bright region on the sheet caused by excessive roll surface wear.
Streak, coating – It is a banded condition caused by non-uniform adherence of roll coating to a work roll. It can be created during hot and / or cold rolling. If generated in the hot rolling process, it is also called hot mill pick-up.
Streak, cold – It is the milky coloured band(s) parallel to the rolling direction which vary in both width and exact location along the length.
Streak, diffusion – It is surface discolouration which can vary from gray to brown and found only on alclad products.
Streak, dirt – It is surface discolouration which can vary from gray to black. It is parallel to the direction of rolling, and contains rolled-in foreign debris. It is normally extraneous material from an overhead location which drops onto the rolling surface and is shallow enough to be removed by etching or buffing.
Streak, grease – It is a narrow discontinuous streak caused by rolling over an area containing grossly excessive lubricant drippage.
Streak, grinding – It is a streak with a helical pattern appearance transferred to a rolled product from a work roll.
Streak, heat – It is the milky coloured band(s) parallel to the rolling direction which vary in both width and exact location along the length.
Streak, herringbone – It is elongated alternately bright and dull chevron markings.
Streak, leveller – It is a streak on the sheet surface in the rolling direction caused by transfer from the leveller rolls.
Streak-line – It is a curve connecting the momentary positions of all fluid particles which have passed through a single, fixed point in the flow field over time. It is visualized by injecting a tracer, such as dye or smoke, at a continuous, constant point, forming a line which shows the path of particles over time that originated from that point. A common example is the smoke from a chimney on a windy day, which forms a streak-line as the smoke moves with the wind over time.
Streak, mill buff – It is a non-uniform surface appearance parallel to the rolling direction.
Streak, pickup – It is a banded condition caused by non-uniform adherence of roll coating to a work roll. It can be created during hot and / or cold rolling. If generated in the hot rolling process, it is also called hot mill pick-up.
Streak, roll – It is a non-uniform surface appearance parallel to the rolling direction.
Streak (stripe) – It is a superficial band or elongated mark which produces a non-uniform surface appearance. A streak is frequently described by source.
Streak, structural – It is a non-uniform appearance on an etched or anodized surface caused by heterogeneities (variabilities) remaining in the metal from the casting, thermal processes, or hot-working stages of fabrication.
Stream degassing practice – In stream degassing, liquid steel is poured into another vessel which is under vacuum. Sudden exposure of liquid stream in vacuum leads to very rapid degassing due to the increased surface area created by break-up of stream into droplets. This process helps the hydrogen dissolved in steel, to be evacuated by a vacuum pump. The major quantity of degassing occurs during the fall of liquid stream. The height of the pouring stream is an important design parameter. Stream degassing technology has two variants in the practice. These variants are (i) ladle to ingot mould degassing, and (ii) ladle to ladle degassing.
Stream-flow – It refers to the volume and velocity of water moving through a stream channel. It is a key component of the water cycle, representing water flowing from land to water bodies. This flow is influenced by several factors, including precipitation, evaporation, and human activities like water withdrawals etc.
Streamline – In fluid mechanics, a streamline is the path followed by a fluid particle as it moves through a flow field, particularly in steady flow where the velocity of the fluid at any given point remains constant over time. It essentially represents a visualization of the flow path of a fluid particle, with the tangent at any point on the streamline indicating the direction of the fluid’s velocity at that point. Streamlines are most commonly associated with steady flow, where the fluid’s velocity at a given point does not change over time.
Streamline a process – It means to make the process more efficient and effective by simplifying it and removing unnecessary steps or activities. It involves identifying and eliminating redundancies, automating tasks, and improving work-flows to reduce waste and increase productivity.
Streamline flow – It is a steady flow of liquid without turbulence. It is normally, not experienced in metal casting.
Streamline pattern – It is a visual representation of fluid motion, where each streamline is an imaginary curve in the flow field whose tangent at any point indicates the direction of the instantaneous velocity of the fluid at that point. These patterns provide a snapshot of the flow’s characteristics, revealing features like vortex shedding, recirculation, and the overall direction and speed of the fluid. Streamline patterns are frequently used in engineering to analyze and design objects to minimize turbulence and drag, ensuring smooth and efficient flow.
Strehl ratio – It is the ratio of the measured on-axis intensity of a light source to that of an ideal hard aperture coherent source of the same size with uniform amplitude and phase. It quantifies the effects of aberrations in optical systems and is maximized when the amplitude and phase are uniform, reaching a value of 1.
Strength – It is the maximum nominal stress a material can sustain. It is always qualified by the type of stress (tensile, compressive, or shear).
Strength, baked – It means compressive, shear, tensile, or transverse strength of a moulded sand mixture when baked at a temperature above 110 deg C and then cooled to room temperature.
Strength coefficient – It is same as strain-hardening exponent (n-value).
Strength, compressive – The ability of a material to resist a force that tends to crush or buckle. The maximum compressive load sustained by a sample divided by the original cross-sectional area of the sample.
Strength criterion – It is a rule, principle, or mathematical formula which defines the conditions under which a material or structure fails or yields under applied stress. It establishes the boundary between elastic behaviour and permanent deformation or fracture by relating stress, strain, and material properties, serving as an important tool in engineering design to ensure stability and prevent failure.
Strengthened alloy – It is a metal alloy whose strength is deliberately increased beyond that of its constituent pure metals through the addition of alloying elements, a process called alloying. This is achieved by impeding the movement of dislocations (defects in the crystal structure) within the metal, making the material harder and more resistant to deformation. Common methods to strengthen alloys include solid solution strengthening, where alloying atoms disrupt the lattice, and precipitation hardening, where second-phase particles form within the matrix.
Strengthening effect – It is the increase in the strength or effectiveness of something through specific modifications, such as solid solution strengthening in materials where solute atoms hinder dislocation movement.
Strengthening mechanism – It refers to a process which increases a metal’s hardness, yield strength, or tensile strength by impeding or obstructing the movement of dislocations, which are linear defects in the crystal structure responsible for plastic deformation. Common strengthening methods include work hardening (strain hardening), grain size reduction, solid solution strengthening, and precipitation strengthening.
Strengthening of metal – It is the process of improving a metal’s mechanical properties, such as hardness and tensile strength, by hindering the movement of dislocations within its crystal lattice, making it more resistant to plastic deformation. This can be achieved through various methods including alloying, heat treatment, and cold working (deformation strengthening).
Strength, flexural – It is the maximum stress which can be borne by the surface fibres in a beam in bending. The flexural strength is the unit resistance to the maximum load before failure by bending. It is normally expressed in force per unit area.
Strength function – It refers to the ability to exert maximum force to overcome resistance, frequently measured as a maximal lift or a force applied to a material. In nuclear physics, a strength function describes the average electro-magnetic transition strengths between states in a nucleus, providing critical data for understanding nuclear reactions and the synthesis of elements.
Strength, impact – It is a material’s ability to absorb and resist energy from sudden, intense forces, preventing fracturing or cracking. It is a measure of toughness, indicating how much energy a material can absorb before it fails, and is crucial for designing cast components subjected to shock loads. Impact strength is quantified through standardized tests like the Charpy and Izod tests.
Strength of association – It is the degree to which knowledge of one’s status on one variable enables prediction of one’s status on another variable to which it is associated with. Measures of strength of association ideally range in absolute value from 0 to 1.
Strength of materials – It is determined using different methods of calculating the stresses and strains in structural members, such as beams, columns, and shafts. The methods used to predict the response of a structure under loading and its susceptibility to several failure modes takes into account the properties of the materials such as its yield strength, ultimate strength, Young’s modulus, and Poisson’s ratio. In addition, the mechanical element’s macroscopic properties (geometric properties) such as its length, width, thickness, boundary constraints and abrupt changes in geometry such as holes are considered. The theory began with the consideration of the behaviour of one- and two-dimensional members of structures, whose states of stress can be approximated as two dimensional, and was then generalized to three dimensions to develop a more complete theory of the elastic and plastic behavior of materials.
Strength reduction factor – It is also known as the phi factor. It is a safety factor applied to the nominal strength of a structural member to account for variations in material properties, construction, and potential inaccuracies in calculations. It effectively reduces the design strength to ensure a level of safety and account for uncertainties.
Strength, shear – It is the maximum shear stress which a material is capable of sustaining. Shear strength is calculated from the maximum load during a shear or torsion test and is based on the original cross-sectional area of the sample.
Strength, tensile – It is the maximum load or force per unit cross-sectional area, within the gauge length, of the sample. The pulling stress needed to break a given sample.
Strength-to-weight ratio – It is a measure of how much strength a material has for its given weight, frequently expressed as a ratio of a material’s load-carrying capacity to its density. It is a key concept in engineering, particularly in applications like aerospace and automotive manufacturing, where the goal is to use materials that are both strong and lightweight to improve efficiency and performance without sacrificing structural integrity.
Strength, wet – It is the strength of an organic matrix composite when the matrix resin is saturated with absorbed moisture, or is at a defined percentage of absorbed moisture less than saturation. (Saturation is an equilibrium condition in which the net rate of absorption under prescribed conditions falls essentially to zero). It is also the strength of an adhesive joint determined immediately after removal from a liquid in which it has been immersed under specified conditions of time, temperature, and pressure.
Strength, yield – It is the stress at the yield point. It is the stress at which a material shows a specified limiting deviation from the proportionality of stress to strain. It is the lowest stress at which a material undergoes plastic deformation. Below this stress, the material is elastic; above it, the material is viscous. It is frequently defined as the stress needed to produce a specified quantity of plastic deformation (normally a 0.2 % change in length).
Stress – It is the internal force per unit area which resists a change in size or shape of a body. It is expressed in force per unit area. It is the intensity of the internally distributed forces or components of forces which resist a change in the volume or shape of a material that is or has been subjected to external forces. Stress can be expressed in force per unit area as ‘nominal’, ‘engineering’, or ‘far stress’ and is calculated on the basis of the original dimensions of the cross section of the specimen. ‘True’ stress is calculated on the basis of the instantaneous rather than nominal area. Stress can be either axial (tension or compression) or shear. It is normally expressed in megapascals (MPa).
Stress amplitude – It consists of one-half the algebraic difference between the maximum and minimum stresses in one cycle of a repetitively varying stress. It refers to half the difference between the maximum and minimum stress experienced by a material during cyclic loading. It is also known as the alternating stress and represents the amount the stress deviates from the mean stress.
Stress analysis – It is the engineering process of evaluating the stresses, strains, and displacements within a piping system under different loading conditions. It is crucial for ensuring the safety, reliability, and longevity of the pipeline by identifying potential failure points and ensuring compliance with design codes. In case of structures, stress analysis is the process of evaluating the distribution of internal forces (stresses) within a material or structure when subjected to loads. It involves understanding how these stresses, which can cause deformation, impact the structure’s behaviour and ability to withstand its intended use.
Stress at work – It is the subjective feelings and physiological responses which result from the psycho-social work environment and put an individual in a position of being unable to cope or respond appropriately to demands being made upon the person. Physiological responses which characterize stress can also arouse due to the physical environment.
Stress concentration – On a macro-mechanical level, it is the magnification of the level of an applied stress in the region of a notch, void, hole, or inclusion.
Stress concentration factor (Kt) – It is the ratio of the maximum stress in the region of a stress concentrator, such as a hole, to the stress in a similar strained area without a stress concentrator. It is a multiplying factor for applied stress which allows for the presence of a structural discontinuity such as a notch or hole. ‘Kt’ equals the ratio of the highest stress in the region of the discontinuity to the nominal stress for the entire section. It is also called theoretical stress concentration factor.
Stress concentration point – It is a specific location in a material where stress levels are considerably higher than in the surrounding material, frequently occurring because of the geometric discontinuities like holes, notches, or sudden changes in cross-sectional area. These points, which can also result from factors like dents or welding, act as focal points for high stress, making the material more susceptible to failure, particularly fatigue cracks.
Stress condition – It is a descriptor of the nature of the stress configuration in a component or at a specific location in a component or test sample in terms of directionality and multiaxiality, hence indicating the degree of constraint on elastic and plastic deformation in the component or sample.
Stress corrosion – It is the preferential attack of areas under stress in a corrosive environment, where such an environment alone has not caused corrosion. It is the frequently rapid, sudden, failure of normally ductile alloys when experiencing tensile stresses in certain and specific corrosive environments. These stresses can be residual internal stresses or from external loading.
Stress-corrosion cracking (SCC) – It is a combined mechanical and electrochemical corrosion process which results in cracking of certain materials. It can lead to unexpected sudden brittle failure of normally ductile steels subjected to stress levels well below their yield strength. Internal stresses in a material can be sufficient to initiate an attack of stress corrosion cracking. Stress corrosion cracking is a cracking process which needs the simultaneous action of a corrodent and sustained tensile stress. This excludes corrosion-reduced sections which fail by fast fracture. It also excludes intercrystalline or transcrystalline corrosion, which can disintegrate an alloy without applied or residual stress. Stress-corrosion cracking can occur in combination with hydrogen embrittlement.
Stress-corrosion hydrogen-induced cracking – It is also known as stress-oriented hydrogen induced cracking (SOHIC). It is a type of sour corrosion where small cracks, oriented perpendicular to the principal stress, form in the presence of hydrogen and stress. This phenomenon can lead to catastrophic failure of materials. It is a form of hydrogen embrittlement where atomic hydrogen, generated from the corrosion of steel in sour environments, diffuses into the metal and combines with the stress to cause cracking.
Stress crack – It is incorrect term when used in metals, since all true cracks are because of the stresses. The term is used in polymers to refer to cracks which are not expected based on known values of applied stresses and can be facilitated by the presence of chemical substances to which the material in question is sensitive. In composites, stress crack means external or internal cracks in a plastic caused by tensile stresses less than that of its short-time mechanical strength, frequently accelerated by the environment to which the plastic is exposed. The stresses which cause cracking can be present internally or externally or can be combinations of these stresses.
Stress cracking – It is the failure of a material by cracking or crazing some-time after it has been placed under load. Time-to-failure can range from minutes to years. Causes include moulded-in stresses, post-fabrication shrinkage or warpage, and hostile environment.
Stress cycle – It is the smallest segment of the stress-time function which is repeated periodically.
stress cycles endured (N) – It is the number of cycles of a specified character (which produce fluctuating stress and strain) which a sample has endured at any time in its stress history.
Stressed skin – It is a rigid construction in which the skin or covering takes a portion of the structural load, intermediate between monocoque, in which the skin assumes all or most of the load, and a rigid frame, which has a non-loaded covering. Typically, the main frame has a rectangular structure and is triangulated by the covering, a stressed skin structure has localized compression-taking elements (rectangular frame) and distributed tension-taking elements (skin).
Stress equalizing – It is a low-temperature heat treatment used to balance stresses in cold-worked material without an appreciable decrease in the mechanical strength produced by cold working.
Stress failure mode – It is a specific, observable way a component or system fails because of the presence of stress, either from forces, temperature, or other factors. It describes the mechanism and physical path through which a failure occurs, rather than the underlying cause, and can manifest as fractures, fatigue, corrosion-induced cracking, buckling, or creep. Identifying these failure modes is crucial for reliability analysis and determining appropriate maintenance strategies.
Stress, fracture – It is the true, normal stress on the minimum cross-sectional area at the beginning of fracture.
Stress gradient – It is the variation of stress through the thickness of a material, which can influence the strength of a sample, particularly in bending tests, by impacting the effective stressed volume and the load redistribution during failure.
Stress, initial (instantaneous) – It is the stress produced by force in a sample before stress relaxation occurs.
Stress-induced leakage current (SILC) – It is an increase in the gate leakage current in a MOSFET (metal-oxide-semi-conductor field-effect transistor) that results from defects generated in the gate oxide because of the electrical stress. These defects, frequently caused by charge trapping within the oxide, create pathways for current flow, leading to higher leakage before the device fails catastrophically. Stress-induced leakage current is a critical factor limiting device miniaturization in modern semi-conductor technologies, affecting power dissipation and reliability.
Stress-intensity calibration – It is a mathematical expression, based on empirical or analytical results, which relates the stress-intensity factor to load and crack length for a specific sample planar geometry. It is also known as Kcalibration.
Stress-intensity factor – It is a scaling factor, normally denoted by the symbol ‘K’ which is used in linear-elastic fracture mechanics to describe the intensification of applied stress at the tip of a crack of known size and shape. At the onset of rapid crack propagation in any structure containing a crack, the factor is called the critical stress-intensity factor, or the fracture toughness. Different subscripts are used to denote different loading conditions or fracture toughnesses as given in Table 3.
| Table 3 – Different subscripts are used to denote different loading conditions or fracture toughnesses | |
| Kc | Plane-stress fracture toughness. The value of stress intensity at which crack propagation becomes rapid in sections thinner than those in which plane-strain conditions prevail. |
| Kl | Stress-intensity factor for a loading condition that displaces the crack faces in a direction normal to the crack plane (also known as the opening mode of deformation). |
| Klc | Plane-strain fracture toughness. The minimum value of Kc for any given material and condition. |
| Kld | Dynamic fracture toughness. The fracture toughness determined under dynamic loading conditions; it is used as an approximation of KIc for very tough materials. |
| Klscc | Threshold stress-intensity factor for stress-corrosion cracking. The critical plane-strain stress intensity at the onset of stress-corrosion cracking under specified conditions. |
| Kq | Provisional value for plane-strain fracture toughness. |
| Kth | Threshold stress intensity for stress-corrosion cracking. The critical stress intensity at the onset of stress corrosion cracking under specified conditions. |
| Delta K | The range of the stress-intensity factor during a fatigue cycle. The rate of crack extension caused by constant-amplitude fatigue loading, expressed in terms of crack extension per cycle of load application, and plotted logarithmically against the stress intensity factor range, delta K. |
Stress-intensity factor range (delta K) – In fatigue, it is the variation in the stress-intensity factor in a cycle, which is Kmax – Kmin. It is the rate of crack extension caused by constant-amplitude fatigue loading, expressed in terms of crack extension per cycle of load application, and plotted logarithmically against the stress intensity factor range, ‘K’.
Stress limit – It is a maximum allowable level of stress which a material or structure can withstand under specific conditions without causing damage, deformation, or failure. This limit can refer to different material properties, such as the elastic limit (the point beyond which a material deforms permanently) or the endurance limit (the stress level below which a material does not fail from fatigue). Choosing the appropriate stress limit is crucial in engineering to ensure safety and reliability in components subjected to loads.
Stress mechanical properties – These refer to the characteristics of a material which describe its response to applied forces, including the determination of stresses and deformation under varying environmental conditions. These properties are assessed through models which analyze the inhomogeneous stress state and the effects of moisture content on the material’s behaviour.
Stress, nominal – It is the stress at a point calculated on the net cross section without taking into consideration the effect on stress of geometric discontinuities, such as holes, grooves, fillets, and so on. The calculation is made by simple elastic theory.
Stress, normal – It is the stress component which is perpendicular to the plane on which the forces act.
Stress-number of cycles – It refers to the relationship between the applied stress and the number of cycles a material can withstand before failure under cyclic loading. It is frequently visualized as an S-N curve, which plots alternating stress (or stress amplitude) against the number of cycles to failure. This curve is a crucial tool for understanding and predicting fatigue life in materials.
Stressometers – In cold rolling mills, stressometers are devices which measure the force distribution and stress within the rolled strip, aiding in flatness control and strip shape optimization. They essentially provide real-time feedback on the stress state of the strip as it is being rolled, allowing for adjustments to be made to maintain the desired flatness and prevent defects like wavy edges or buckling.
Stress point – It refers to either a point of high stress concentration in a material, frequently leading to failure, or a specific point on a stress-strain curve representing a material’s properties, such as the yield point (where plastic deformation begins) or the ultimate tensile strength (the maximum stress before failure). The term’s meaning depends on the context, whether it is a physical location in a structure or a characteristic on a material’s load-bearing graph.
Stress propagation – It is the transmission of mechanical stress in the form of stress waves through a solid material. When a force is applied to a material, it generates stress waves which travel, or propagate, through the body of the material, undergoing changes in amplitude and direction because of reflections and interactions with other materials. This phenomenon is crucial in understanding how materials respond to dynamic loading conditions, such as impacts, and is fundamental to technologies like non-destructive testing and earthquake monitoring.
Stress raisers – These are the design features (such as sharp corners) or mechanical defects (such as notches) which act to intensify the stress at these locations.
Stress range (Sr) – It is the algebraic difference between the maximum and minimum stress in one cycle, i.e., Sr = Smax – Smin.
Stress rate – It refers to the rate at which stress changes over time. It generally describes how quickly a ‘stress’ condition is developing or changing.
Stress ratio (A or R) – It is the algebraic ratio of two specified stress values in a stress cycle. Two normally used stress ratios are namely (i) the ratio of the alternating stress amplitude to the mean stress, A = Sa/Sm, and (ii) the ratio of the minimum stress to the maximum stress, R = Smin/Smax.
Stress reduction factor (SRF) – It is a dimensionless parameter which quantifies how stress changes in a rock mass or soil during and after an excavation, particularly in underground structures. It indicates the presence and effect of geological weaknesses, like joints or faults, which can alter stress distribution and affect the stability of the surrounding ground, allowing for more accurate geo-technical design and risk assessment.
Stress relaxation – It is the decrease in stress under sustained, constant strain. It is also called stress decay. Stress relaxation in gaskets refers to the gradual loss of compression force (pushback) over time while the gasket material remains compressed. This phenomenon occurs because the molecules within the gasket material can slip and rearrange, reducing the pressure it exerts. This ‘pushback’ is crucial for effective sealing, and stress relaxation can lead to leaks and reduced sealing performance if not accounted for. Stress relaxation is also the time-dependent decrease in stress in a solid under constant constraint at constant temperature.
Stress-relaxation curve – It is a plot of the remaining or relaxed stress as a function of time. The relaxed stress equals the initial stress minus the remaining stress. It is also known as stress-time curve.
Stress relaxation testing – It is a method used to determine how a material’s stress decreases over time when subjected to a constant strain. This test is crucial for understanding the time-dependent behaviour of materials, especially viscoelastic materials like polymers and composites.
Stress, relaxed – It is the initial stress minus the remaining stress at a given time during a stress- relaxation test.
Stress relief – It is the removal or reduction of residual stress by thermal treatment, mechanical treatment (shot peening, surface rolling, stretching, bending, and straightening), or vibratory stress relief.
Stress relief annealing – The main objective of the stress relief annealing is to remove the internal stresses produced in the steel material because of (i) plastic deformation, (ii) non-uniform cooling, and (iii) phase transformation. Stress relief annealing process is used to ensure there is reduced risk of distortion of the work piece during machining, welding, or further heat treatment cycles. Stress relief annealing process involves heating the steel material to a temperature of around 600 C to 650 deg C. The temperature is maintained constantly for a few hours and then the steel material is allowed to cool down slowly in still air. No phase transformation takes place during stress relief annealing.
Stress-relief cracking – It is also known as stress rupture cracking and reheat cracking. It is the cracking in the heat-affected zone or weld metal which occurs during the exposure of weldments to high temperatures during post weld heat treatment, in order to reduce residual stresses and improve toughness, or high-temperature service. It is due to reheating of the concern when welding quenched and tempered steel grades and heat-resistant steels containing substantial amounts of carbide formers, such as chromium, molybdenum, and vanadium. When weldments of these steels are heated more than around 500 deg C, inter-granular cracking along the prior austenite grain boundaries can take place in the coarse grain heat affected zone (CGHAZ). Stress relief cracking is thought to be closely related to the phenomenon of creep rupture. Furthermore, during reheating, the re-precipitation of carbides is likely to occur, further increasing the hardness. The precipitation of carbides during stress relaxation alters the delicate balance between resistance to grain boundary sliding and resistance to deformation within the coarse grains of the heat affected zone (HAZ).
Stress-relief embrittlement – It is loss of toughness in heat-affected zone and / or weld metal as a result of stress relieving a welded structure. Stress-relief cracking leads to intergranular cracking of weld. It is also known as post weld heat treat cracking and reheat cracking.
Stress-relief heat treatment – It is the uniform heating of a structure or a portion thereof to a sufficient temperature to relieve the major portion of the residual stresses, followed by uniform cooling.
Stress relieving – It consists of heating to a suitable temperature, holding long enough to reduce residual stresses, and then cooling slowly enough to minimize the development of new residual stresses.
Stress, residual – It is the stress existing in a body at rest, in equilibrium, at uniform temperature, and not subjected to external forces. It is frequently caused by the forming and curing process.
Stress reversal – It is a phenomenon where the type of stress within a material or structural member changes, typically from tensile to compressive or vice versa. This reversal can be a result of fluctuating or repeated external forces, such as wind loads acting on a truss, or internal material changes like drying. It is a critical concept in fatigue analysis since repeated or completely reversed stress cycles significantly influence a material’s endurance and potential for failure.
Stress riser – It is also called or stress raiser. It is a physical feature in a component, such as a hole, groove, notch, or sharp corner, which concentrates stress in that localized area, creating a much higher stress level than in the surrounding material. These geometric irregularities interrupt the smooth flow of stress through the component, similar to how water flow increases around a rock in a river. Stress risers weaken a component by creating points of high stress where cracks can initiate and propagate, ultimately leading to failure.
Stress-rupture strength – It is also called creep-rupture strength. It is the stress which causes fracture in a creep test at a given time, in a specified constant environment.
Stress-rupture test – It is also called creep-rupture test. It measures how long a material can withstand a constant load at a high temperature before it fractures. Unlike creep tests, which focus on deformation over time, stress rupture tests are always performed to failure to determine the time to rupture. This data helps predict material performance and failure points in critical applications like power generation.
Stress, shear – It is the component of stress tangent to the plane on which the forces act.
Stress state – It is a complete description of the stresses within a homogeneously stressed volume or at a point. The description needs, in general, the knowledge of the independent components of stress.
Stress-strain – It is the stiffness at a given strain.
Stress–strain analysis – It is an engineering discipline which uses several methods to determine the stresses and strains in materials and structures subjected to forces. In continuum mechanics, stress is a physical quantity which expresses the internal forces that neighbouring particles of a continuous material exert on each other, while strain is the measure of the deformation of the material. In simple terms stress can be defined as the force of resistance per unit area, offered by a body against deformation. Stress is the ratio of force over area (S = R/A, where ‘S’ is the stress, ‘R’ is the internal resisting force and ‘A’ is the cross-sectional area). Strain is the ratio of change in length to the original length, when a given body is subjected to some external force (Strain= change in length ÷ the original length).
Stress-strain behaviour in bending – A characteristic feature of bending is the inhomogeneous (non-uniform) nature of the deformation. Hence, in a bent sample the strain and stress at a given point are dependent on the location of the point with respect to the neutral axis of the cross-sectional area of the sample. In cases where the applied bending moment varies along the length of the sample (as in three-point bending), the strains and stresses become dependent on axial location as well. Because of these inhomogeneities, a full appreciation of stress and strain distributions is of utmost importance in bending analyses and computations. Stress-strain relationships, strain curvature, and stress-moment equations are important. The formulations are for elastic, elastic plastic, and fully plastic bending conditions.
Stress-strain curve – It is simultaneous readings of load and deformation, converted to stress and strain, plotted as ordinates and abscissae, respectively, to get a stress-strain diagram. It is a graph in which corresponding values of stress and strain from a tension, compression, or torsion test are plotted against each other. Values of stress are normally plotted vertically (ordinates or y-axis) and values of strain horizontally (abscissas or x-axis). It is also known as deformation curve and stress-strain diagram.
Stress–strain diagram – For the reparation of stress-strain diagram, the sample is placed in the testing machine and a force ‘F’ is applied. A mechanical or electrical device – strain gauge or extensometer is used to measure the quantity which the sample stretches between the gauge marks when the force is applied until the sample fails. The stretch, both elastic (recoverable) and plastic (permanent), is converted into strain by division of the change in length (extension or elongation) by the original length. Using the original cross-sectional area of the sample, the load ‘F’ is converted into stress, and an engineering stress-strain diagram is obtained. Engineering stress, or nominal stress, ’S’ is defined as S = F/A0 where ‘F’ is the tensile force and ‘A0’ is the initial cross-sectional area of the gauge section. Engineering strain, or nominal strain, ‘e’, is defined as e = (L-L0)/L0 where ‘L0’ is the initial gauge length (original distance between the gauge marks), and ‘L’ is the distance between the gauge marks after force ‘F’ is applied. When force-elongation data are converted to engineering stress and strain, a stress-strain diagram which is identical in shape to the force-elongation diagram can be plotted. The advantage of dealing with stress versus strain rather than load against elongation is that the stress-strain curve is essentially independent of the dimensions of the sample.
Stress, tensile – It is the normal stress caused by forces directed away from the plane on which they act.
Stress tensor – It is a second-rank tensor which describes the internal forces within a solid body or fluid under external forces. It is a 3×3 matrix which represents the stress acting on a material at a specific point. The components of the stress tensor represent both normal (tension / compression) and shear stresses.
Stress-time curve – It is same as stress-relaxation curve.
Stress, torsional – It is the shear stress on a transverse cross-section caused by a twisting action.
Stress, true – It is the stress along the axis calculated on the actual cross section at the time of observation instead of the original cross-sectional area. It is applicable to tension and compression testing.
Stretch-bending test – It is a simulative test for sheet metal formability in which a strip of sheet metal is clamped at its ends in lock beads and deformed in the centre by a punch. Test conditions are chosen so that fracture occurs in the region of punch contact.
Stretcher leveling – It is the leveling of a piece of sheet metal (i.e., removing warp and distortion) by gripping it at both ends and subjecting it to a stress higher than its yield strength.
Stretcher straightening – It is a process for straightening rod, tubing, and shapes by the application of tension at the ends of the stock. The products are elongated a definite quantity to remove warpage.
Stretcher strains – These are elongated markings which appear on the surface of some sheet materials when deformed just past the yield point. These markings lie approximately parallel to the direction of maximum shear stress and are the result of localized yielding.
Stretch former – It is a machine which is used to perform stretch forming operations. It is also a device adaptable to a conventional press for accomplishing stretch forming.
Stretch forming – It is the shaping of a metal sheet or part, normally of uniform cross section, by first applying suitable tension or stretch and then wrapping it around a die of the desired shape.
Stretcher grip marks – These are transverse indentations left by the gripper jaws of the stretching machine on the ends of a product.
Stretcher levelling – It is a term used to describe both the levelling of rolled materials and the straightening of extruded and drawn materials by imparting sufficient permanent extension to remove distortion.
Stretcher strains – These are elongated markings that appear on the surfaces of some materials when they are deformed just past the yield point. These markings lie approximately parallel to the direction of maximum shear stress and are the result of localized yielding.
Stretcher strain markings – These are permanent surface distortions which can occur on stretching. They can appear as either flamboyant patterns or Luders lines. Their onset and extent depend on the type of material and the degree of stretching.
Stretch forming – It is the forming of sheet, bars, and rolled or extruded sections over a form block of the needed shape while the work-piece is held in tension. The work metal is frequently stretched just beyond its yield point (normally 2 % to 4 % total elongation) to retain permanently the contour of the form block. The four methods of stretch forming are (i) stretch draw forming, (ii) stretch wrapping, also called rotary stretch forming. (iii) compression forming, and (iv) radial draw forming.
Stretching – It is the extension of the surface of a metal sheet in all directions. In stretching, the flange of the flat blank is securely clamped. Deformation is restricted to the area initially within the die. The stretching limit is the onset of metal failure.
Stretch zone – It is a region of crack extension from a pre-existing cracklike imperfection caused by crack tip blunting and subsequent ductile tearing.
Stretford process – It is a liquid-phase redox process which is used to remove hydrogen sulphide (H2S) from gas streams and convert it into elemental sulphur. It involves oxidizing hydrogen sulphide in an alkaline solution containing vanadium as a catalyst. The process is particularly suitable for removing hydrogen sulphide from several gas streams, including coke oven gas, and has been widely adopted in commercial applications.
Striated – It is used to describe a wavelike or rippled pattern on a fracture surface. It can be caused by microstructural features (such as a lamellar eutectoid structure) or cyclic loading (fatigue striations).
Striation – It is a fatigue fracture feature, frequently observed in electron micrographs, which indicates the position of the crack front after each succeeding cycle of stress. The distance between striations indicates the advance of the crack front across that crystal during one stress cycle, and a line normal to the striations indicates the direction of local crack propagation. In geology, Striations consists of prominent parallel scratches left on bedrock by advancing glaciers.
Stribeck curve – Stribeck demonstrated that the coefficient of friction is directly proportional to the viscosity of the lubricant and the difference in the speeds of the contact surfaces, and inversely proportional to the pressure which is exerted on the contact surfaces. In the Stribeck curve, the coefficient of friction is plotted against the expression ZN/P (sometimes referred to as the Hersey number). ZN/P is defined as (lubricant viscosity Z × shaft speed N) / bearing contact pressure P. The Stribeck curve has three distinct zones known as (i) boundary lubrication, (ii) mixed lubrication, and (iii) hydrodynamic lubrication. There is also an overlapping regime of elasto-hydrodynamic lubrication.
Stribeck effect – It is a non-linear dependence of friction on sliding speed, particularly observed in tribological interactions, where it describes the transition from boundary to mixed friction conditions.
Stribeck friction – It refers to the variation in friction force in sliding contacts, particularly under lubricated conditions, where friction decreases with increased sliding speed until mixed or full-film lubrication is achieved, after which it can remain constant or vary due to viscous and thermal effects. This behaviour is modeled by the Stribeck friction model, which encompasses different friction types from static to viscous depending on the parameters used.
Strike – It is a thin electro-deposited film of metal to be overlaid with other plated coatings. It is a plating solution of high covering power and low efficiency designed to electroplate a thin, adherent film of metal. In geology, strike is the direction, or bearing from true north, of a vein or rock formation measure on a horizontal surface.
Strike off – It is a straight edge, or metal bar, to cut the sand level with the top of the drag or cope flask. It is also the operation of removing excess sand from top of core box or flask.
Striker plate – It is a steel plate placed immediately below the anvil. It is also known as an anvil.
Striking – It consists of electro-depositing, under special conditions, a very thin film of metal which facilitates further plating with another metal or with the same metal under different conditions.
Striking surface – It consists of those areas on the faces of a set of metal forming dies which are designed to meet when the upper die and lower die are brought together. The striking surface helps protect impressions from impact shock and aids in maintaining longer die life.
String – It is a long flexible tool made from fibres twisted together into a single strand, or from multiple such strands which are in turn twisted together. String is used to tie, bind, or hang other objects. It is also used as a material to make things. String can also be a component in other tools, and in diverse devices.
Stringer – In wrought materials, it is an elongated configuration of micro-constituents or foreign material aligned in the direction of working. The term is normally associated with elongated oxide or sulphide inclusions in steel. In geology, stringer is a narrow vein or irregular filament of a mineral or minerals traversing a rock mass.
Stringer bead – It is a continuous weld bead made without appreciable transverse oscillation (weaving motion).
Strip – It is a flat-rolled metal product of some maximum thickness and width arbitrarily dependent on the type of metal; narrower than sheet. It is a roll-compacted metal powder product. It is also the removal of a powder metallurgy compact from the die. It is an alternative to ejecting or knockout. In mining, strip means to remove the overburden or waste rock overlying an orebody in preparation for mining by open pit methods. It is also a process or solution used for the removal of a coating from a base metal or an undercoat. The term strip is also used to remove a coating from the base metal or undercoat.
Strip casting – It is a continuous casting process where molten metal is solidified directly into a thin, metallic strip by passing it between two counter-rotating, water-cooled rolls. This technique allows for rapid solidification, which refines the metal’s micro-structure and results in a product closer to its final form, reducing the number of downstream processing steps and saving energy and costs compared to conventional methods.
Strip cooling system – In hot strip mill, it is a crucial process which cools the hot steel strip to a desired temperature after it has been rolled. This cooling is important for achieving the desired final steel properties, facilitating handling and transportation, and controlling the microstructure of the steel. strip cooling system cools the strip rolled by the finishing mill and it is located on the run-out table between the finishing mill and the down coiler. The cooling system is designed as a laminar flow system on both top and bottom, incorporating a line side head tank system. The cooling zone is divided into the required cooling banks which consists of intensive cooling banks for faster cooling, normal cooling banks for regular cooling, and the cooling banks for fine temperature control in order to achieve the desired cooling patterns and coiling temperatures for dual phase and TRIP (transformation induced plasticity) steels. The combination of laminar cooling and edge masking system prevents excessive cooling of the strip edges, thereby minimizing stress differences across the strip width.
Strip mill – It is a type of metal rolling mill which processes metal slabs into long, continuous, flat strips of metal with a consistent width and thickness. These mills use a series of rolling stands and other components to continuously reduce the thickness of the metal and impart the desired width, producing long coils of steel or other metals.
Strip mine – It is an open-pit mine, normally a coal mine, operated by removing overburden, excavating the coal seam, then returning the overburden.
Strip mining – It is a form of surface mining which is used to strip away a layer or seam of soil, natural vegetation, and rocks (known as overburden) to extract the mineral deposits underneath.
Stripped die method – It is a specific method of removal of the compact after pressing, which keeps it in position between the punches while the die is retracted either upward or downward until the compact is fully exposed and freed by an upward withdrawal of the upper punch. The method is in in general use.
Stripper – It is a plate designed to remove, or strip, sheet metal stock from the punching members during the withdrawal cycle. Strippers are also used to guide small precision punches in close-tolerance dies to guide scrap away from dies and to assist in the cutting action. Strippers are made in two types namely fixed and movable.
Stripper pins – On certain moulding machines, these are a series of pins (normally four in number) which support the rammed flask-half at the parting surface so that the mounted pattern can be drawn by lowering.
Stripper punch – It is a punch which serves as the top or bottom of a metal-forming die cavity and later moves farther into the die to eject the part or compact.
Stripping – It is removing a coating from a metal surface. It is also removing a foundry pattern from the mould or the core box from the core. It also refers to the process of removing a formed part from a die or tool. This is a common step after a metal forming operation like drawing, stamping, or extrusion, where the produced component needs to be separated from the mold or equipment used to shape. Stripping is also a separation process where one or more substances are removed from a liquid by contacting it with a gaseous phase. This process is frequently used in industrial applications to remove contaminants from waste streams or to purify liquids. Stripping is also removing the pattern from the mould or core from core box.
Stripping agent – It is a chemical substance which removes unwanted layers or components from a surface or system. Depending on the application, a stripping agent can be used to remove paint and lacquer from surfaces, break down chemical complexes in liquid membrane systems, or prevent water from displacing asphalt binder from aggregate in road construction.
Stripping column – The product obtained at the bottom of the extractive distillation column consists of NFM in which the extracted aromatic substances are dissolved. The non-aromatic content is low (usually in parts per million) because of there is pressure drop. This flow is conveyed into the aromatics-column, which is operated under vacuum. In this column the pure aromatics are separated from the N-Formylmorpholine. N-Formylmorpholine depleted from the aromatic substances is collected as the bottom product. It is cooled in the heat exchanger system prior to be returned to the extractive distillation column. N-Formylmorpholine is sent to the extractive distillation column through (i) centre re-boiler on the extractive distillation, (ii) re-boiler on solvent recovery column, and (iii) N-Formylmorpholine re-boiler on the stripper column. Solvent cooler serves as a trim cooler for NFM. The bottom of the stripper column is heated by means of the two continuous re-boilers, which are heated by benzene-toluene vapours and heated by means of N-Formylmorpholine. The reflux to the stripping column serves to remove the solvent in the lower section of the column. The vapour liquid mixture discharges from the re boiler is fed below the chimney tray in the stripping column. Traces of the solvent flash are washed back by the aromatics reflux and directed into the lower part of the column. There are a number of trays and the feed tray is the fifth tray. The temperature at the top is 56 deg C while the temperature at the bottom is 119 deg C. Pressure is around 36 kilo-pascal.
Stripping machine – It is a device for removing the pattern from a mould or a core from the core box.
Stripping plate – It is a plate, formed to the contour of the pattern, which holds the sand in place while the pattern is drawn through the plate.
Stripping ratio – The ratio of tons removed as waste relative to the number of tons of ore removed from an open-pit mine.
Stripping time – In oil-oxygen and no bake mixture, it is the moment when the core box can be satisfactorily drawn from the core, or pattern from the sand.
Strip rolling – It is a metal forming process which reduces the thickness of a metal strip by passing it between rotating rollers. This process, also known as flat rolling, involves applying compressive forces in a specific area called the roll gap to plastically deform and thin the metal, increasing its length and altering its mechanical properties. The end result is a thin, flat metal product like sheets or coils, which are then used in several industries.
Stroke – It is length of fall of the ram in case of a pile hammer.
Stoker-fired boiler – Stoker firing method has been the most economical method for burning coal in almost all industrial boilers rated for less than 100 tons per hour of steam. This type of boiler has been capable of burning a wide range of coals, from bituminous to lignite, as well as by-products of waste solid fuels. However, over the years, this type of boiler has become less popular because of the technological advancement. In stoker-fired boiler, coal is pushed, dropped, or thrown on to a grate to form a fuel-bed. Stokers are divided into two general classes namely (i) overfeed, in which fuel is fed from the above, and (ii) underfeed, in which the fuel is fed from the bottom. Under the active fuel-bed, there is a layer of fuel ash, which along with air flow through the grate keeps metal parts at allowable operating temperatures. Stoker can be a chain-grate overfeed stoker, and a traveling grate overfeed stoker respectively.
Stroke restricted machines – In stroke-restricted machines, the quantity of deformation which can be done is fixed by the stroke of the machine. If sufficient force or energy to carry out the operation is not available, then the machine stalls and a larger machine is to be used. Mechanical presses fall into this category, as a crank or eccentric determines the amount of ram movement.
Stroke (up or down) – It is the vertical movement of a ram during half of the cycle, from the full open to the full closed position or vice versa.
Strong acid – It is a chemical compound which completely ionizes or dissociates into its constituent ions when dissolved in a solution, typically water. This means that virtually all the acid molecules break apart, releasing hydrogen ions (H+) and a conjugate base. Strong acid completely dissociates in solution as per the reversible reaction HA + S = HS+ + A-HA+S↽−−⇀SH++A−, or to such an extent that the concentration of the undissociated species HA is too low to be measured. Any acid with a pKa of less than approximately -2 is normally considered a strong acid. An example is hydrochloric acid (HCl).
Strong base – It is a substance which completely dissociates into ions when dissolved in water, producing a high concentration of hydroxide ions (OH-). This complete ionization leads to a substantial increase in the solution’s pH value. Strong bases are also characterized by their ability to neutralize acids effectively and their corrosive nature, especially at higher concentrations. Strong base is a basic chemical compound which remove a proton (H+) from (or deprotonate) a molecule of even a very weak acid (such as water) in an acid–base reaction. Common examples of strong bases include hydroxides of alkali metals and alkaline earth metals, like sodium hydroxide, calcium hydroxide respectively. Because of their low solubility, some bases, such as alkaline earth hydroxides, can be used when the solubility factor is not taken into account.
Strong stirring-vacuum oxygen decarburization (SS-VOD) process – This process has been developed by Kawasaki Steel Corporation (now JFE Steel Corporation). It is a steelmaking process where molten steel is treated under vacuum to remove impurities, including carbon, and improve its quality. This is achieved by combining oxygen blowing to react with and remove carbon, along with vigorous stirring (frequently with argon) to improve the reaction and ensure uniformity.
Strontium (Sr) – It is a chemical element having atomic number 38. It is an alkaline earth metal. It is a soft silver-white yellowish metallic element that is highly chemically reactive. The metal forms a dark oxide layer when it is exposed to air. Strontium has physical and chemical properties similar to those of calcium and barium. It occurs naturally mainly in the minerals celestine and strontianite, and is mostly mined from these.
Strontium-doped lanthanum manganite (LSM) – It is a perovskite ceramic material, represented by the chemical formula La(1-x)SrxMnO3, which is widely used as a cathode in solid oxide fuel cells (SOFCs) because of its high electrical conductivity, excellent electro-chemical activity for oxygen reduction, and thermal stability. The doping of strontium (Sr) into lanthanum (La) within the manganite perovskite structure improves its performance, generating oxygen vacancies for improved efficiency and leading to applications beyond solid oxide fuel cells, such as in water electrolysis, magnetic sensors, and catalysis.
Structural – It means steel member of specific cross-sectional dimensions used in fabrication and / or construction, (e.g., H-beam, angle, I-beam, and W-flange etc.).
Structural adhesive – It is the adhesive which is used for transferring needed loads between adherends exposed to service environments typical for the structure involved.
Structural analysis -It is a branch of solid mechanics which uses simplified models for solids like bars, beams and shells for engineering decision making. Its main objective is to determine the effect of loads on physical structures and their components. In contrast to theory of elasticity, the models used in structural analysis are frequently differential equations in one spatial variable. Structures subject to this type of analysis include all which withstand loads, such as buildings, bridges, aircraft and ships. Structural analysis uses ideas from applied mechanics, materials science and applied mathematics to compute a structure’s deformations, internal forces, stresses, support reactions, velocity, accelerations, and stability. The results of the analysis are used to verify a structure’s fitness for use, frequently precluding physical tests. Structural analysis is hence a key part of the engineering design of structures.
Structural assessment testing – It is a process where engineers evaluate a structure’s condition, typically focusing on identifying potential problems and assessing its ability to handle loads. This involves visual inspections, material testing, and load calculations to determine a structure’s strength and durability.
Structural behaviour – It describes how a structure responds to internal forces and external influences like loads and environmental factors, determining its performance, safety, and durability. It encompasses the study of a structure’s material properties, physical features, and mechanical characteristics under stress, including its deformations, stability, and strength over its service life. Understanding structural behaviour is crucial for the design of safe, functional, and efficient structures.
Structural bond – It is a bond which joins basic load- bearing parts of an assembly. The load can be either static or dynamic.
Structural ceramics – Ceramics are non-metallic, inorganic engineering materials processed at a high temperature. The general term ‘structural ceramics’ refers to a large family of ceramic materials used in an extensive range of applications. Included are both monolithic ceramics and ceramic-ceramic composites. Chemically, structural ceramics include oxides, nitrides, borides, and carbides. Several processing routes are possible for structural ceramics and are important since the micro-structure, and hence the properties, are developed during processing.
Structural channel – It is a type of (normally structural steel) beam with ‘C’ cross-section. It is used primarily in building construction and civil engineering. Its cross section consists of a wide ‘web’, normally but not always oriented vertically, and two ‘flanges’ at the top and bottom of the web, only sticking out on one side of the web. It is distinguished from I-beam or H-beam or W-beam type steel cross sections in that those have flanges on both sides of the web.
Structural damping – It refers to the process where mechanical energy is dissipated as heat within a vibrating structure, typically because of the internal friction within the material or at interfaces between components. This energy loss reduces oscillations by effectively converting some of the structure’s kinetic and elastic energy into thermal energy, which is lost to the surroundings. It is a form of hysteretic or solid damping, distinct from viscous damping, where the energy loss is related to the cycle amplitude rather than velocity.
Structural defects – These defects are because of the inappropriate structure causing inferior properties. These defects are mostly of metallurgical origin.
Structural design – It is the process of creating a safe, functional, and durable structure by analyzing and determining the appropriate materials, dimensions, and reinforcements to withstand different loads and forces. It involves understanding how forces act on a structure and designing it to resist those forces without failure. Basically, it bridges the gap between architectural design and the practical construction of a building or infrastructure.
Structural development defects – These defects are because of the development of inappropriate structure during processing (strain localizations etc.).
Structural drawing – It is a type of technical drawing which depicts the design and working drawings for building as well as technological structures. It includes a plan or set of plans for the building or other structures. Structural drawings are mainly concerned with the load-carrying members of a structure. They outline the size and types of materials to be used, as well as the general demands for connections. They do not address architectural details like surface finishes, partition walls, or mechanical systems. The structural drawings guide in detailing, fabricating, and installing parts of the structure. Structural drawings are of three types namely (i) design drawings, (ii) detail fabricating drawings, and (iii) erection drawings. Structural detail fabrication drawing includes all the details needed for the fabrication of the structures.
Structural engineer – Structural engineer designs, analyzes, and oversees the construction of structures to ensure they are safe, stable, and can withstand natural forces like wind and earthquakes. They apply principles of physics, mathematics, and engineering to determine how a structure’s components, such as foundations, beams, and columns, a5e going to function under different loads and stresses, ultimately ensuring the integrity and longevity of the entire structure.
Structural engineering – It is a sub-discipline of civil engineering in which structural engineers are trained to design the ‘bones and joints’ which create the form and shape of human-made structures. Structural engineers are also to understand and calculate the stability, strength, rigidity and earthquake-susceptibility of built structures for buildings and non–building structures. The structural designs are integrated with those of other designers such as architects and building services engineer and frequently supervise the construction of projects by contractors on site. They can also be involved in the design of machinery, medical equipment, and vehicles where structural integrity affects functioning and safety.
Structural equation modelling – The relationships between a series of inter-related and predictor variables can be handled using this method which is also known as linear structure relations (LISREL). The structural relationship between the variable which is measured and the latent construct can be defined using this tool. As a comprehensive method, it is beneficial for testing hypotheses as well as testing, presenting, and estimating, theoretical networks of relations which are mostly linear between variables. For measurement equivalence it can also be applied in complex analyses for first-order and higher-order constructs.
Structural failure – It refers to the loss of structural integrity, or the loss of load-carrying structural capacity in either a structural component or the structure itself. Structural failure is initiated when a material is stressed beyond its strength limit, causing fracture or excessive deformations. One limit state which is to be accounted for in structural design is ultimate failure strength. In a well-designed system, a localized failure does not cause immediate or even progressive collapse of the entire structure.
Structural fatigue – It is the progressive damage and potential failure of a material or component caused by repeated or cyclic loading, even at stress levels below its material strength. This damage initiates as microscopic cracks which grow with each stress cycle, leading to a sudden and frequently unpredictable failure. Common causes include stress concentrations, surface imperfections, and material discontinuities, while factors like the stress level, number of cycles, and material properties influence its occurrence and rate.
Structural formula – It is a graphical representation of the molecular structure and geometry of a particular chemical compound, showing how the atoms are arranged in real, three-dimensional space. Chemical bonding within the molecule is also shown, either implicitly or explicitly. When known with certainty, structural formulas are very useful since they allow chemists to visualize the molecules and the structural changes which occur in them during chemical reactions.
Structural fracture mechanics – It is the field of structural engineering concerned with the study of load-carrying structures that includes one or several failed or damaged components. It uses methods of analytical solid mechanics, structural engineering, safety engineering, probability theory, and catastrophe theory to calculate the load and stress in the structural components and analyze the safety of a damaged structure.
Structural integrity – It is the ability of an item, either a structural component or a structure consisting of several components, to hold together under a load, including its own weight, without breaking or deforming excessively. It assures that the construction performs its designed function during reasonable use, for as long as its intended life span. Items are constructed with structural integrity to prevent catastrophic failure, which can result in injuries, severe damage, death, and / or monetary losses.
Structural integrity and failure – These consist of an aspect of engineering which deals with the ability of a structure to support a designed structural load (weight and force etc.) without breaking and includes the study of past structural failures in order to prevent failures in future designs.
Structural isomer – It is a compound which contains the same number and type of atoms, but with a different connectivity (i.e. arrangement of bonds) between them, e.g., butanol H3C−(CH2)3−OH, methyl propyl ether H3C−(CH2)2−O−CH3, and diethyl ether (H3CCH2−)2O have the same molecular formula C4H10O but are three distinct structural isomers.
Structuralism – It is a method of interpretation and analysis of aspects of human cognition, behaviour, culture and experience, which focuses on relationships of contrast between elements in a conceptual system. It works to uncover the structures that underlie all the things which humans do, think, perceive, and feel. Since under the management, work is done within specific organizational patterns and since worker-superior roles imply authority relationships, the structure or framework within which these patterns and relationship occur is known as structuralism. It is based on bureaucratic or formal organization and gives particular attention to line and staff relationships, authority structure, the process of decision making, and the effect of organizational life on the individual worker.
Structural load – It is a mechanical load (more generally a force) applied to structural elements. A load causes stress, deformation, displacement or acceleration in a structure. Structural analysis analyzes the effects of loads on structures and structural elements. Excess load can cause structural failure, so this is to be considered and controlled during the design of a structure. Particular mechanical structures are subject to their own particular structural loads and actions. Engineers frequently evaluate structural loads based upon published regulations, contracts, or specifications. Accepted technical standards are used for acceptance testing and inspection.
Structural materials – These are substances chosen and used in construction, manufacturing, and engineering mainly for their mechanical properties, such as strength, stiffness, and durability, to support and bear loads and maintain the stability of structures. These materials can be natural or synthetic, including stone, wood, steel, concrete, polymers, and composites, and are selected based on their ability to withstand forces and external actions without excessive deformation or failure.
Structural mechanics – It is the computation of deformations, deflections, and internal forces or stresses (stress equivalents) within structures, either for design or for performance evaluation of existing structures. It is one subset of structural analysis. Structural mechanics analysis needs input data such as structural loads, the structure’s geometric representation and support conditions, and the materials’ properties. Output quantities can include support reactions, stresses and displacements. Advanced structural mechanics can include the effects of stability and non-linear behaviours.
Structural member – It is a fundamental component of a structure which supports and transfers loads safely to the ground. These components are designed to withstand specific forces, like tension, compression, or bending, and are connected to form a functional system. Examples of structural members include beams, columns, slabs, and braces, each serving a specific role in the overall structural integrity.
Structural panel – It is a thin, flat composite material which is strong enough to resist applied loads and is used in construction for walls, roofs, and floors.
Structural pipe fitting – It is also known as a slip-on pipe fitting, clamp or pipe clamp is used to build structures such as handrails, guardrails, and other types of pipes or tubular structure. They can also be used to build furniture and theatrical riggings. The fittings slip on the pipe and are normally locked down with a set screw. The set screw can then be tightened with a simple hex wrench. Because of the modular design of standard fittings, assembly is easy, only simple hand tools are required, and risks from welding a structure are eliminated. Other advantages of using structural pipe fittings are easy installation and reconfigurable design. Since there are no permanent welds in the structure, the set screws of the fittings can simply be loosened, allowing them to be repositioned. The project can be disassembled and stored if needed, or even taken apart with fittings and pipe recycled into a new project.
Structural quality – It is quality of steel which refers to the overall characteristics and attributes that ensure a steel material is suitable for use in building construction and other structural applications. These qualities include strength, ductility, toughness, weldability, and adherence to established standards and specifications. It is not just about the steel’s inherent properties, but also how it is fabricated and assembled to form a reliable and durable structure.
Structural quality steel – It is steel applicable to the different classes of structures, indicated by the standard specifications, which is suitable for the different mechanical operations employed for the fabrication of such structures. Structural quality steel represents the quality of steel produced under regular or normal manufacturing conditions.
Structural reaction injection moulding (SRIM) – It is a variation of reaction injection moulding (RIM) where a fibre mesh or other structural elements are added to the mould before the liquid polymers are injected. This process produces parts with improved strength and durability by incorporating the reinforcing material directly into the final product.
Structural robustness – It is the ability of a structure to withstand events like fire, explosions, impact or the consequences of human error, without being damaged to an extent disproportionate to the original cause. A structure designed and constructed to be is not to suffer from disproportionate collapse (progressive collapse) under accidental loading. Buildings of some kinds, especially large-panel systems and precast concrete buildings, are disproportionately more susceptible to collapse; others, such as in situ cast concrete structures, are disproportionately less susceptible. The method used in making a structure robust typically depends on and be tailored to the kind of structure it is, as in steel framed building structural robustness is typically achieved through appropriately designing the system of connections between the frame’s constituents.
Structurals – These are steel product group which includes I-beams, H-beams, wide-flange beams, and sheet piling. These products are used in the construction of multi-story buildings, industrial buildings, bridge trusses, vertical highway supports, and riverbank reinforcement.
Structural sandwich construction – It is a laminar construction comprising a combination of alternating dissimilar simple or composite materials assembled and intimately fixed in relation to each other so as to use the properties of each to attain specific structural advantages for the whole assembly.
Structural shape – It is a piece of metal of any of several designs accepted as standard by the structural branch of the iron and steel industries.
Structural stability – In grease lubrication, it refers to the ability of a grease to maintain its consistency and structure under operating conditions, such as shear forces, temperature changes, and prolonged use. This property is crucial for the grease to effectively reduce friction, protect lubricated surfaces, and perform its intended function.
Structural steel – Structural steel is a material used for steel construction, which is formed with a specific shape following certain standards of chemical composition and strength. They can also be defined as hot rolled products, with a cross section of special form like angles, channels, tees, rounds, squares, beams, and hollow pipes both round and square etc. There has been an increasing demand for structural steel for construction purposes mainly because the selection of structural steel for the framing system of a building brings numerous benefits to the construction projects. All other materials are measured against the standard of structural steel and hence structural steel is the material of choice for the architects, designers, and engineers. . Structural steel shapes, sizes, chemical composition, mechanical properties such as strengths, and storage practices etc., are regulated by standards. Structural steel shapes, such as I-beams, have high second moments of area, so can support a high load without excessive sagging.
Structural steel design – It is an area of structural engineering which is used to design steel structures. The design and use of steel frames are normally used in the design of steel structures. More advanced structures include steel plates and shells. In structural engineering, a structure is a body or combination of pieces of the rigid bodies in space which form a fitness system for supporting loads and resisting moments. The effects of loads and moments on structures are determined through structural analysis.
Structural steel shape – It is a steel member with a specific, standardized cross-sectional profile, such as an I-beam, H-beam, channel, or angle, designed to provide support, strength, and durability to construction projects like buildings and bridges. These shapes are formed through processes like rolling and are selected for their high strength-to-weight ratio and load-bearing capacity to ensure structural integrity.
Structural stiffness – It is the resistance of a structure to deformation under load, which is influenced considerably by its cross-sectional geometry and the material properties, such as Young’s modulus.
Structural steel work – It involves the processes of fabricating, fitting, welding, and erecting these steel components to form an integral, load-bearing part of a structure.
Structural streak – It is a non-uniform appearance on an etched or anodized surface caused by heterogeneities (variabilities) remaining in the metal from the casting, thermal processes, or hot-working stages of fabrication.
Structural system – It is also called structural frame. It refers to the load-resisting sub-system of a building or object. The structural system transfers load through inter-connected elements or members.
Structural tubing – It is a type of hollow metal or plastic product designed for use in construction and engineering, providing strength and stability to structures. It’s characterized by its ability to carry imposed loads and improve the overall structural integrity of buildings and other constructions. It is frequently referred to as ‘hollow structural sections’ (HSS) and is normally made of steel. It has high strength-to-weight ratio and provides substantial strength while being relatively lightweight compared to solid steel, it can be used in many shapes (round, square, rectangular) and sizes to suit different design requirements.
Structural weight – It is the combined weight of all structural components which make up a structure, such as beams, and columns etc., calculated by multiplying the material density and volume of each part. It is a critical factor in structural design, since this self-weight is one of the dead loads a structure is to withstand to maintain stability and safety against both its own weight and external forces.
Structural working drawing – The process of preparing working drawings for structural engineering work is normally referred to as structural detailing. The general principle followed is to break down the total structure into individual elements such as columns, beams, and floor slabs etc., and then to detail each element in turn. The three main groups of drawings for illustrating steelwork structures are general arrangement drawings, fixing details, and details of individual members. General arrangement drawings include steel framing plans, elevations and sections. Steel framing plans indicate the positions and sizes of beams at a specific floor or roof level, together with the positions and sizes of columns. Elevations and sections show columns and beams as well as additional members such as wind bracing. It is necessary to identify each steel member by a distinctive mark reference whenever it appears on a drawing. The same mark is painted on the actual member before it leaves the workshop for dispatch to the site. A common system is to mark the horizontal grid lines on the steel framing plans with numbers-1, 2, 3 etc. -and the vertical grid lines with letters – A, B, C etc.
Structure – A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as biological organisms, minerals and chemicals. Abstract structures include data structures in computer science. Types of structure include a hierarchy (a cascade of one-to-many relationships), a network featuring many-to-many links, or a lattice featuring connections between components that are neighbors in space. Structure also refers to a system of interconnected members designed to support external loads and maintain stability under various forces, including buildings, bridges, and infrastructure. As applied to a crystal, structure is the shape and size of the unit cell and the location of all atoms within the unit cell. As applied to micro-structure, structure is the size, shape, and arrangement of phases. In cast structure, it is the size and disposition of the constituents of a metal as cast.
Structured cabling – It is a system for design of the telephone and data communications cable systems of a building.
Structured illumination microscopy (SIM) – It is a super-resolution fluorescence microscopy technique which uses patterned light to achieve higher resolution than conventional wide-field microscopy. By illuminating a sample with multiple, shifted Moire fringes and computational reconstruction, SIM captures high-frequency spatial information that is otherwise undetectable, enabling two-to-threefold improvement in resolution.
Structured team approach – It is also known as a team-based structure. It is a method of organizing work where individuals are grouped into teams, each responsible for specific tasks or objectives, and work collaboratively to achieve them. This approach emphasizes teamwork, collaboration, and problem-solving, making it suitable for organizations with complex projects or rapid change.
Structure factor (F) – It is the ratio of the amplitude of the wave scattered by all the atoms of a unit cell to the amplitude of the wave scattered by a single electron. It is a mathematically formulated term that relates the positions and identities of atoms in a crystalline material to the intensities of X-ray or electron beams diffracted from particular crystallographic planes.
Structure failure – It is the loss of a structure’s ability to perform its intended design function, frequently resulting in the complete or partial inability to carry its intended load, leading to inadequate functionality, safety issues, or collapse. It can occur from several factors including design flaws, use of sub-standard materials, manufacturing errors, corrosion, repeated stress, human error in construction or maintenance, and instability from natural causes.
Structure-insensitive properties – These are material properties which are determined more by the composition of the material than by its structure. Examples are density, elastic modulus, and thermal conductivity.
Structure mills – These mills are also called shape mills or section mills. In these mills medium and smaller sizes of beam and channel sections and other structural shapes are rolled normally from billets or blooms.
Structure-sensitive properties – These are material properties which are strongly dependent on microstructural features and defect structure. Examples are yield-strength and fracture toughness.
Strukturbericht designation – It is a system of classifying crystal structures by analogy to other known structures, often used as a supplement to space group designations, especially historically. It goes beyond just the symmetry of the crystal structure by also describing the positions of individual atoms.
Strut – It is a structural member designed to resist axial compressive forces. It acts as a support, transferring loads and providing stability to structures like trusses, frames, and temporary supports during construction. Struts can be horizontal, inclined, or vertical, with vertical compression members frequently specifically referred to as columns. They are distinct from ties, which resist tension, and are crucial for preventing components from buckling under load.
Strut channel – It is a standardized formed structural system used in the construction and electrical industries for light structural support, frequently for supporting wiring, plumbing, or mechanical components such as air conditioning or ventilation systems. A strut is normally formed from a metal sheet, folded over into an open channel shape with inwards-curving lips to provide additional stiffness and as a location to mount interconnecting components. Increasingly, struts are being constructed from fiberglass, a highly corrosion-resistant material which is known for its lightweight strength and rigidity. Struts normally have holes of some sort in the base, to facilitate inter-connection or fastening strut to underlying building structures.
Stub – It typically refers to a track which branches off from a main line and has a single, non-connecting end. This end is normally secured with a bumping post or other obstruction. In essence, it is a side track which does not connect to another track at its terminating end.
Stud – It is a projecting pin serving as a support or means of attachment.
Stud arc welding – It is also known as arc stud welding. It is a normally used method for joining a metal stud, or a fastener, to a metal work piece. The process has been used as an alternative metal-fastening method since the 1940s. A large number of specially designed and manufactured metal studs are welded by this process regularly in such diverse industries as construction, shipbuilding, automotive, and hard goods, as well as in miscellaneous industrial applications. The stud arc welding process represents an alternative to other welding processes, and is also a substitute for other fastening procedures, such as drilling and tapping, bolting, and self-tapping screws. Stud arc welding is similar to many other welding processes, including arc and percussion welding, in that the base (weld end) of a specifically designed stud is joined to a base material by heating both parts with an arc which is drawn between the two. Equipment which is unique to this process regulates the arc length and arc dwell time. After an arc is struck, the stud weld end and the work piece surface are brought to the proper temperature for joining and, after a controlled period of time, the two heated surfaces are brought together under pressure, creating a metallurgical bond capable of developing the full strength of the stud. There are two basic types of stud arc welding, which are differentiated by the source of welding power. One type uses direct current power provided by a transformer / rectifier. The second type uses power discharged from a capacitor storage bank. The process based on a direct current power source is known as stud arc welding, whereas the process which utilizes capacitors is known as capacitor discharge stud welding (CDSW). Both the processes overlap in some areas of application. Normally, the stud arc welding process is used in applications which need similar stud and work piece metals, the work piece thickness is greater in relation to the stud diameter, and an accommodation is to be made for the stud flash (fillet). In contrast, the capacitor discharge stud welding process is used extensively when welding to thin sheet metal, and is used frequently with dissimilar work piece and stud alloys. It is also used in cases where marks on the opposite side of the work piece are to be avoided or minimized. With this process, the stud diameter is limited to smaller sizes. The factors on which process selection is to be based are fastener size, base-metal thickness, base-metal composition, and reverse-side marking requirements.
Stud welding – It is a welding process which joins a metal stud to a workpiece by creating an arc between the stud and the base material, melting both surfaces, and then pressing them together. It is a fast and reliable method for attaching fasteners without needing to access the backside of the work-piece. There are two main types namely capacitor discharge (CD) and drawn arc stud welding.
Student-Newman-Keuls (SNK) test – It is a non-parametric post ANOVA test, also called a post hoc test. It is used to analyze the differences found after the performed F-test (ANOVA) is found to be significant, for example, to locate where differences truly occur between means.
Student t-test (t) – It is a statistical hypothesis test in which the test statistic follows a student’s t-distribution if the null hypothesis is true, for example, a t-test for paired or independent samples.
Study endpoint (also known as outcome, dependent variable, criterion variable or response variable) – It is the ‘effect’ variable whose ‘behaviour’ one is trying to explain using one or more explanatory variables in the study.
Stuffing box – It is a mechanical seal which prevents fluid or gas leakage around a moving rod or shaft as it passes through a housing or cylinder. It consists of packing rings compressed by a gland nut within an annular space around the shaft, creating a seal. Stuffing boxes are used on pumps, valves, and in marine engines to keep fluids, gases, and contaminants from leaking out or into the engine’s crankcase.
Styrene – It is an organic compound with the chemical formula C8H8. It is a colourless liquid known for its sweet, pungent odour. It is a volatile substance, meaning it easily evaporates, and is widely used in the production of plastics and rubber. Styrene is a key component in poly-styrene, a common plastic found in several products, and is also used in the synthesis of synthetic rubber.
Styrene-butadiene rubber – It is a synthetic polymerization product consisting of styrene and butadiene whose characteristics are similar to natural rubber. Tensile and cut resistance are good. Abrasion, heat and ozone resistance are better than natural rubber.
Styrene-butadiene-styrene (SBS) – It is a synthetic thermoplastic elastomer composed of alternating blocks of polystyrene (hard) and butadiene (soft) segments, giving it rubber-like elasticity at room temperature and the ability to be processed like plastic when heated. This unique combination makes it a useful material which retains elasticity at low temperatures and is durable under high temperatures. Styrene-butadiene-styrene is used in a variety of applications, including asphalt modification for roads, adhesives, and sealants.
Styrofoam pattern – It is an expendable pattern of foamed plastic, especially expanded polystyrene, used in manufacturing castings by the lost foam process.
Sub-assembly – Assembly is the collection of two or more parts. The assembly process is a series of joining processes (either permanent or non-permanent) in which parts are oriented and added to the build. It is a mass-increasing process in which the macro-geometry is established by the positioning of the components. Sub-assembly is an assembly which is included within another assembly or sub-assembly.
Sub-assembly drawing – Several equipments are assembled with many pre-assembled components as well as individual parts. These pre-assembled units are known as sub-assemblies. A sub-assembly drawing is an assembly drawing of a group of related parts, which form a part in a more complicated equipment. Example of such drawings is the tail-stock in a lathe.
Sub-bituminous coal – It is a type of coal which falls between lignite and bituminous coal in terms of carbon content and energy value. It is characterized by a lower sulphur content and moderate heating value, making it a useful fuel source, particularly for rotary kilns and power generation.
Sub-boundary structure – It is also called sub-grain structure. It is a network or low-angle boundaries, normally with misorientations less than 1-degree within the main grains of a microstructure.
Sub-categories – These are criteria of environmental, social and economic viability, technical feasibility, and degree of confidence.
Sub-classes – These are optional subdivision of resource classification based on project maturity principles resulting from the combination of sub-categories.
Sub-classification on propensity scores – It is a means of performing propensity-score analysis in which the substantive analysis is repeated on different groups having roughly the same propensity scores. The analysis results from the different groups are then combined into one final result through weighted averaging.
Sub-contract – It is a contract entered into by the main contract to a contract (main contract) under which the main contractor agrees with the sub-contractors that the sub-contractor is going to perform their obligations under the main contract in return for consideration of some kind. In general, the other party to the main contract is obliged to accept the sub-contractor’s performance if the sub-contractor fulfils all that the main contractor had agreed to do under the main contract. Sub-contracts can hence be an effective way of delegating contractual obligations to a third party. The main contractor remains liable for the performance of the main contract, with the result that it is liable to the other party to the main contract for any default in performance by the subcontractor.
Sub-contracting – It is the practice of assigning, or outsourcing, part of the obligations and tasks under a contract to another party known as a sub-contractor. Sub-contracting is especially prevalent in areas where complex projects are the norm, such as construction.
Sub-contractor – It is an individual or organization appointed by a main contractor to perform part of a larger project or contract, typically for specialized skills or tasks that the main contractor is not equipped to handle. The sub-contractors work under a specific contract (a sub-contract) with the main contractor and is responsible for delivering their portion of the work as per the agreed-upon terms, while the main contractor retains overall responsibility for the project’s completion.
Sub-cooling – It is also known as undercooling. It is the process of cooling a liquid below its saturation point (the temperature at which it boils or condenses at a given pressure). In simpler terms, it is when a liquid is cooled to a temperature lower than what it js normally to be at a specific pressure. This is a common practice in refrigeration systems and steam turbine cycles.
Sub-criterion – It a is a secondary, subordinate, or subsidiary criterion which helps break down a main criterion into more specific, actionable components for making a judgment or decision. Sub-criteria serve as more detailed standards or requirements, guiding evaluations by providing specific aspects to consider within a broader category.
Sub-critical annealing – In sub-critical annealing, a degree of attention is to be exercised in selecting the annealing temperature since the rate of heating also has an effect. For rapid heating rates, the Ac1 temperature is to be higher than with slow heating rates. If Ac1 temperature has been incorrectly determined and the real value is exceeded, then austenite gets formed. This austenite is going to or is not going to transform upon subsequent cooling from the annealing temperature, resulting in unwanted retained austenite, untempered martensite, or both. When sub-critical (process) annealing large loads, it is expedient to use a furnace temperature which is somewhat higher than Ac1 temperature to speed up the process. Such a method, however, demands close control to prevent any of the charge from becoming austenitized. Prolonged annealing induces higher ductility at the expense of strength. A serious embrittlement problem can arise after prolonged treatment, with severe forming operations, cracks are liable to occur.
Sub-critical boiler – It is a boiler which operates at a pressure lower than the critical pressure of water (around 22.1 megapascals), where liquid and steam phases exist separately. This means the boiler produces a mixture of liquid water and steam, which is then separated before being used.
Sub-critical flow – It is an open channel flow condition characterized by a flow depth higher than the critical depth and a Froude number less than one. In this state, the flow is slow and stable, similar to a tranquil or streaming flow, where gravitational forces dominate and disturbances can travel both upstream and downstream.
Sub-critical crack growth (SCG) – It is a failure process in which a crack initiates at a pre-existing flaw and grows until it attains a critical length. At that point the crack grows in an unstable fashion leading to catastrophic failure. Typical examples of sub-critical crack growth processes are fatigue failure and stress corrosion.
Sub-critical heat-affected zone (SCHAZ) – It is a region within the heat-affected zone (HAZ) of a welded or thermally processed material where the temperature during the process remains below the critical transformation temperature (A1 temperature for steel). This region experiences thermal cycling, which can lead to changes in micro-structure and, in some materials, softening.
Sub-critical mass – It is the fissile material of a quantity insufficient in volume or geometrically arranged in such a way that no chain reaction can be maintained.
Sub-critical system – It is one where a nuclear fission chain reaction is not self-sustaining, meaning it needs an external neutron source to maintain the reaction. In such a system, the neutron multiplication factor (keff) is less than 1, preventing the chain reaction from repeating itself without continuous external neutron input. This concept applies to certain types of nuclear reactors, like accelerator-driven systems (ADS), and is also a condition achieved when a reactor is intentionally shut down.
Sub-cutaneous blow-hole – It consists of blow-holes at or near the surface of solidified metal, covered with a thin layer of metal. It can also be called pinhole porosity.
Sub-economic Demonstrated resources – Sub-economic Demonstrated resources are similar to Economic Demonstrated resources in terms of certainty of occurrence and, although considered to be potentially economic in the foreseeable future, these resources are judged to be Sub-economic at present. These resources are also at a proved and probable level of certainty.
Sub-grain – It is a portion of a crystal or grain, with an orientation slightly different from the orientation of neighbouring portions of the same crystal.
Sub-level – It is a level or working horizon in a mine between main working levels.
Sublimation – It is the transition of a substance directly from the solid to the gaseous state, without passing through the liquid state. The verb form of sublimation is sublime, or less preferably sublimate. Sublimate also refers to the product obtained by sublimation. The point at which sublimation occurs rapidly is called critical sublimation point, or simply sublimation point. Notable examples include sublimation of dry ice at room temperature and atmospheric pressure, and that of solid iodine with heating.
Sub-marginal Economic resources – Sub-marginal Economic resources are resources which require a substantially higher commodity price or a major cost-reducing advance in technology to render them economic.
Sub-marine communications cable – It is a telephone or telegraph cable which is substantially under water.
Submerged arc furnace (SAF) – It is an electric furnace which is used in smelting and reducing metals, where the electrodes are immersed in the charge, minimizing air exposure and maximizing heat transfer. This type of furnace is mainly used for producing ferroalloys and other metals like yellow phosphorus and silicon. In general, the furnace is constructed to have a hearth with carbonaceous materials and a shaft with refractory brick lining. The furnace charge, which consists of ore and reducing agents, is fed from the top, and the electrodes are buried in the charge. The furnace charge becomes a part of the electric circuit, and the resistive heating of the charge provides the necessary energy. Because of the submerged nature of the arc, it is known as submerged arc furnace. Electrodes are made of carbonaceous materials in order to withstand high temperature. They come as prebaked or self-baking types. Prebaked electrodes are more expensive than self-baking ones and are used for the production of alloys which cannot allow any contamination by iron. Self-baking electrodes, also known as Soderberg, make the carbon electrodes in situ by baking carbon paste with heat from the smelting process. They are used in furnaces with a large capacity. A submerged arc furnace for the production of ferroalloys operates at low secondary voltages and high secondary currents, and these electric requirements are provided by transformers
Submerged arc welding (SAW) – It is an arc welding process in which the arc is concealed by a blanket of granular and fusible flux. Heat for submerged arc welding is generated by an arc between a bare, solid-metal (or cored) consumable wire or strip electrode and the work piece. The arc is maintained in a cavity of molten flux or slag, which refines the weld metal and protects it from atmospheric contamination. Alloy ingredients in the flux can be present to improve the mechanical properties and crack resistance of the weld deposit. In a typical setup for automatic SAW process, a continuous electrode is being fed into the joint by mechanically powered drive rolls. A layer of granular flux, just deep enough to prevent flash through, is being deposited in front of the arc. Electrical current, which produces the arc, is supplied to the electrode through the contact tube. The current can be direct current with electrode positive (reverse polarity), with electrode negative (straight polarity), or alternating current. After welding is completed and the weld metal has solidified, the unfused flux and slag are removed. The unfused flux can be screened and reused. The solidified slag can be collected, crushed, resized, and blended back into new flux. Re-crushed slag and blends of re-crushed slag with unused (virgin) flux are chemically different from new flux. Blends of re-crushed slag can be classified as a welding flux, but cannot be considered the same as the original virgin flux. In this process, pressure is not used, and filler metal is obtained from the electrode and sometimes from a supplemental source (welding rod, flux, or metal granules).
Submerged arc welded (SAW) pipe – It is a type of steel pipe manufactured using a welding process where the arc is shielded by a blanket of granular flux, preventing atmospheric contamination and enabling deep weld penetration. This method is particularly suited for large-diameter, thick-walled pipes used in high-pressure and high-temperature applications like oil and gas pipelines.
Submerged belt conveyor – It is a special type of conveyor in which a portion of the belt moves through a metallic trough (casing) which is filled with free flowing, powdered material at the loading end. The moving belt with holes makes the material flow to the unloading end of the trough.
Submerged-electrode furnace – It is a furnace which is used for liquid carburizing of parts by heating molten salt baths with the use of electrodes submerged in the ceramic lining.
Submerged entry nozzle (SEN) – It is a refractory tube used in continuous casting to transport molten steel from the tundish to the mould, ensuring that the steel remains submerged and prevents re-oxidation. It plays a crucial role in controlling the steel flow, temperature, and the overall casting process.
Submerged entry nozzle (SEN) clogging – It refers to the build-up of solid inclusions and other materials on the inner wall of the submerged entry nozzle during continuous steel casting. This build-up obstructs the flow of molten steel, leading to several issues like uneven mould flow and potential steel quality problems. Short submerged entry nozzle life because of the clogging is normally an indicator of low level of steel cleanliness. Small alumina (Al2O3) inclusions in low carbon aluminum killed (LCAK) steel are known to cause nozzle clogging. Hence, submerged entry nozzle clogging frequency is another crude method to evaluate steel cleanliness.
Submerged structure – It is a man-made construction built and located entirely or partially underwater, serving purposes such as coastal protection, infrastructure, and resource extraction. These structures are designed to withstand water pressure and corrosive environments, and examples include underwater pipelines, tunnels, breakwaters, and platforms for offshore activities.
Submerged zone – In marine application, it is the portion of the structure from about 0.3 meters to 1 meter below mean low tide down to the mud line.
Submersible pump – It is a hermetically sealed pump designed to be fully submerged in the liquid it is pumping. It is normally used for several applications, including water supply, drainage, and irrigation, where it efficiently pushes fluids to the surface.
Sub-micron powder – It is the powder whose particles are smaller than 1 micro-meter.
Sub-microscopic – It means below the resolution of the microscope
Submission drawings – Submission drawings are prepared with reference to the by-laws drafted and implemented by an authority. These are sent to the authorities for their approval and include index plans, detailed drawings, elevation drawings, and other sectional plans.
Sub-optimization – It is the optimization of a part of a large, complex engineering system with several parameters. Sub-optimization of all sub-parts of a large system does not in general lead to optimization of the whole system. Sub-optimization is successful in improving quality only when the sub-systems are loosely coupled.
Sub-sample – It is a portion taken from a sample. A laboratory sample can be a sub-sample of a gross sample. Similarly, a test portion can be a sub-sample of a laboratory sample.
Subsidiary organization – It is an organization which is controlled or owned by another organization, known as the parent or holding organization. The parent organization typically owns more than 50 % of the subsidiary’s voting shares, allowing it to influence the subsidiary’s operations, finances, and strategic decisions. Subsidiaries can be wholly-owned (100 % ownership) or partially-owned.
Sub-sieve analysis – It refers to determining the average particle size of metal powders using methods finer than traditional sieving. This is frequently achieved by measuring the specific surface area of the powder, which is then related to the average particle size. Methods like the Fisher sub-sieve sizer use air permeability to determine this specific surface area.
Sub-sieve fraction – It consists of particles which pass through a 44 micrometers (325 mesh) screen.
Sub-sieve size – The preferred term is sub-sieve fraction.
Sub-soil condition – It refers to the physical characteristics, properties, and stability of the soil layer beneath the top soil. These conditions, including its density, compaction, water content, and the type of particles present (sand, silt, and clay), are critical for understanding how well the soil can support structures in construction.
Sub-soil zone – In marine application, it is the portion below the mud line, where the structure has been driven into the ocean bottom.
Sub-sonic diffuser – It is a device, typically a duct with an increasing cross-sectional area, which slows down a fluid’s velocity and increases its static pressure, converting kinetic energy into pressure energy. Normal in heating ventilation and air conditioning (HVAC) and aerodynamic applications, these diffusers achieve this by expanding the flow path, which decreases the flow speed and Mach number while increasing pressure.
Sub-sonic flow – It is defined as a flow field where the local Mach number is less than 1 at every point. It is characterized by smooth streamlines and disturbances which propagate both upstream and downstream throughout the entire flow field.
Sub-sonic speed – It refers to a speed which is less than the speed of sound in a given medium. This term is frequently used in aerodynamics to describe objects moving slower than the speed of sound, a condition measured by a Mach number less than 1.
Sub-sow block (die holder) – It is a block used as an adapter in order to permit the use of forging dies which otherwise does not have sufficient height to be used in the particular unit or to permit the use of dies in a unit with different shank sizes.
Substance – It refers to a material, or matter, of which something is made, and in its purest form, it can be either a single element or a compound with a fixed composition.
Sub-stations – They are components of the power transmission process. They transform voltage from high to low, or the reverse, or perform any of several other important functions. Substation varies in size and configuration. Between the generating station and consuming point, electric power can flow through several substations at different voltage levels. A substation consists of (i) outdoor switch yard, (ii) a building which houses the control equipment, and (iii) the fencing.
Substituent – It is an atom or a group of atoms which substitutes or replaces another atom or group of atoms within a larger molecule as the product of a chemical reaction, thereby becoming a moiety of the newly formed compound, generally without causing any significant change to other parts of the same molecule, e.g., a hydroxyl group can be substituted for any of the hydrogen atoms in benzene to form phenol.
Substitutional element – It is an alloying element with an atomic size and other features similar to the solvent which can replace or substitute for the solvent atoms in the lattice and form a significant region of solid solution in the phase diagram.
Substitutional solid solution – It is a type of solid solution where solute atoms replace solvent atoms within the crystal lattice of the solvent. This occurs when the solute and solvent atoms have similar sizes and properties. For example, brass (copper-zinc) and bronze (copper-tin) are substitutional solid solutions.
Substitution reaction – It is a type of chemical reaction in which one functional group or substituent within a larger compound replaces or is substituted for another functional group or substituent.
Substrate – It is the material, work-piece, or substance on which the coating is deposited. It is a material upon the surface of which an adhesive-containing substance is spread for any purpose, such as bonding or coating. It is a broader term than adherend. In electronic devices, it is a body, board, or layer of material on which some other active or useful material(s) or component(s) can be deposited or laid, e.g., electronic circuitry laid on an alumina ceramic board. In catalysts, it is the formed, porous, high-surface area carrier on which the catalytic agent is widely and thinly distributed for reasons of performance and economy.
Substrate hardness – It refers to the inherent resistance of a base material (the material beneath a coating or other layer) to local plastic deformation, a critical factor influencing the durability and performance of a coated system. As an example, in thin films, a harder substrate can considerably alter a film’s contact behaviour, and the interaction between the film and its underlying substrate impacts the overall measured hardness.
Substrate temperature – In thermal spraying, the temperature attained by the base material as the coating is applied. Proper control of the substrate temperature by intermittent spraying or by the application of external cooling minimizes stresses caused by substrate and coating thermal expansion differences.
Sub-structure – It is also called sub-boundary structure or sub-grain structure. It is a network or low-angle boundaries, normally with misorientations less than 1-degree within the main grains of a microstructure.
Subsumption architecture – It is a reactive robotic architecture heavily associated with behaviour-based robotics. It has been widely influential in autonomous robotics and elsewhere in real-time AI (artificial intelligence). Subsumption architecture is a control architecture. Instead of guiding behaviour by symbolic mental representations of the world, subsumption architecture couples sensory information to action selection in an intimate and bottom-up fashion.
Sub-surface corrosion – It is the formation of isolated particles of corrosion products beneath a metal surface. This results from the preferential reactions of certain alloy constituents to inward diffusion of oxygen, nitrogen, or sulphur.
Sub-surface porosity – It refers to the presence of void spaces (pores) within a material located beneath its surface. These pores can be discrete spherical or elongated holes, and their distribution can be uniformly scattered, in clusters, or in linear patterns. They can be difficult to detect visually, requiring specialized testing to identify.
Subsystem – It is a self-contained, functional unit that is part of a larger system. It has its own inputs, outputs, and internal structure, and it interacts with other subsystems to achieve the overall system’s goals. Subsystems can be further broken down into smaller subsystems or components.
Sub-zero treatment – It is cooling hardened steel to a temperature sufficiently below zero deg C to promote the transformation of any retained austenite to martensite.
Succession – It is the act or process of following in order or sequence.
Succession planning – It is defined as a purposeful, concentrated and systematic effort made by an organization to ensure leadership continuity, to retain and develop knowledge and intellectual capital for the future, and to encourage individual employee’s growth and development. The concept of succession planning includes identification and development of successors for the key position in the organization. Succession planning process is a continuous process in an organization. It is essentially about preparing future leaders and ensuring a strong talent pipeline for the organization’s long-term success.
Suck-blow process – It is a process used for glass container manufacturing with forming machines. Glass is sucked from the tank of molten glass into the parison mould and then cut by shears. A plunger inside the mould produces a hollow space in the glass which is then enlarged by blowing. Following this initial blow, and then reheating, the parison is transferred to the finishing mould for the finishing blow.
Suck-in – It is a defect caused when one face of a forging is sucked in to fill a projection on the opposite side.
Suction – It is the process of creating a vacuum, a space with reduced air pressure. It is a day-to-day term for the movement of gases or liquids along a pressure gradient with the implication that the movement occurs because the lower pressure pulls the gas or liquid. However, the forces acting in this case do not originate from just the lower pressure side, but also from the side of the higher pressure, as a reaction to the pressure difference. When the pressure in one part of a physical system is reduced relative to another, the fluid or gas in the higher-pressure region will exert a force relative to the region of lowered pressure, referred to as pressure-gradient force. If all gas or fluid is removed the result is a perfect vacuum in which the pressure is zero. Hence, no negative pressure forces can be generated. Accordingly, from a physics point of view, the objects are not pulled but pushed.
Suction cup – It is a semi-spherical cup of flexible material such as rubber. By pressing the cup onto a glass surface and removing air from inside the cup, the vacuum thus created holds the cup and glass together. Suction cups are used in both the manual and automatic handling and conveyance of glass.
Suction filter – It is a coarse filter located in the suction line of a pump to protect it from large particles of dirt and debris, preventing damage and extending its lifespan. Mounted on the suction side, it prevents contaminants from entering sensitive equipment, maintaining optimal performance by removing impurities before they reach the pump or other downstream components.
Suction nozzle – It is a specialized component with an opening which creates a vacuum to remove fluids, waste, or other substances, frequently by connecting to a vacuum source or pump. The design of a suction nozzle varies depending on its application, but it typically features a specifically shaped tip and can include features to prevent tissue damage or to control the flow of material being suctioned, such as vacuum cleaners, or industrial equipment.
Suction pipe – It is a pipe or flexible hose which transports fluids, air, or solid particles by creating a vacuum, drawing the material in from a source rather than pushing it out. It works by creating negative pressure to pull substances through the pipe, and is crucial for several applications, including water pumps, drainage systems, and industrial fluid transfer, where it is to be durable enough to withstand collapsing under the internal pressure created by the pump.
Suction port – It is a point or opening where a negative pressure (vacuum) is applied to draw in or remove fluids, gases, or other materials. It is a crucial component of suction devices used in several applications, including industrial processes.
Suction valve – It is also known as a foot valve or inlet valve. It is a valve on the inlet side of a pump, compressor, or engine which controls the intake of fluids or gases into the system. It opens because of a pressure difference, allowing flow in, and closes to prevent backflow or system pressure loss. Key functions include maintaining system pressure, ensuring proper operation, and preventing issues like pump depriming or vacuum collapse.
Suctorians – These are a type of protozoan frequently found in waste-water treatment systems, specifically within the activated sludge. They are characterized by their stalk-like appearance and the use of specialized tentacles (haptocysts) to capture and consume other protozoa and bacteria. The presence of suctorians normally indicates a healthy and stable waste-water treatment process with good oxygen levels and low organic matter.
Suggestion – It refers to employees’ proposals as to how their work-place are to be enhanced through improvements introduced into the organizational areas and processes. In order to encourage such feed-back among their employees, a number of organizations introduce specially-tailored organizational solutions called employee suggestion schemes / programmes, idea management systems or ‘kaizen teian’ (Japanese term).
Suggestion scheme – It is a management tool, which encourages employees to contribute ideas for improvement and innovation in the organization. It is based on rationale that creative talent exists in the employees and each of them has the ability and is well placed to make suggestions to improve the way the job is being done at the work-place. It is a formal mechanism, which encourages employees to contribute constructive ideas for improving their organization. It is a formal channel which encourages every employee to suggest ideas which can be helpful in solving or avoiding problems or improving work process or the work environment. Through the suggestion scheme, the employees can participate directly in the improvement of the productivity in the organization. The employees find their job more meaningful and interesting when they participate in the decision-making process involving their work.
Sulphate attack – It is a process where sulphate ions in the environment react with concrete, leading to its deterioration. This attack is mainly caused by sulphate-containing salts found in soil, groundwater, or seawater, which react with the cement paste in concrete. This reaction results in the formation of expansive products like ettringite and gypsum, causing cracking, expansion, and loss of strength in the concrete.
Sulphate resisting cement – Ordinary portland cement (OPC) is susceptible to the sulphate attack. Sulphate reacts with the free calcium hydroxide to form calcium sulphate and hydrate the tricalcium aluminate (C3A) to form calcium-sulpho-aluminates., the volume of which is around 227 % of the volume of the original aluminates. Sulphate resisting cement contains lower percentage of tricalcium aluminate and tetra calcium alumino ferrite (C4AF) which are considered as the most affected compounds by sulphates. This cement has higher percentage of silicates in comparison with ordinary portland cement. For this type of cement, di calcium silicate (C2S) represents a high proportion of the silicates. Some standards limit the maximum tricalcium aluminate content to 3.5 % minimum and fineness to 2,500 square centimeters per gram. The cement has low early strength. Its resulted heat of hydration is little higher than that resulted from low heat cement. Its cost is higher than ordinary portland cement because of the special requirements of material composition, including addition of iron powder to the raw materials.
Sulphidation – It is the reaction of a metal or alloy with a sulphur-containing species to produce a sulphur compound which forms on or beneath the surface on the metal or alloy.
Sulphide – It is a compound of sulphur and some other element.
Sulphide capacity – It is the ability of metallurgical slags to extract sulphur from a gas phase, expressed through the relationship between the partial pressures of oxygen and sulphur in the gas and the percent of sulphur in the slag. It is influenced by slag composition and temperature, and is important for controlling sulphur content during steelmaking operations.
Sulphide flotation – It is a mineral processing method which uses collectors to make hydrophobic sulphide mineral surfaces attach to air bubbles, allowing them to be separated from hydrophilic gangue materials in a slurry. This technique is used in the mining industry to recover valuable metals like copper, nickel, and zinc from crushed ore by creating a froth containing the desired sulphide minerals, which are then skimmed off for further processing.
Sulphides inclusions – These are iron sulphide (FeS), manganese sulphide (MnS), aluminum sulphide (Al2S3), calcium sulphide (CaS), magnesium sulphide (MgS), zirconium sulphide (Zr2S), and others. The sulphides are frequently the consequence of the calcium treatment applied in order to modify the oxide inclusions, but the little and finely dispersed calcium sulphide highly refractory inclusions can be detrimental for the casting procedure (nozzle clogging) and for the damaging effect on steel. On the contrary the manganese sulphide non-metallic inclusions (frequently modified by the combination with calcium sulphide) are exploited for improving the cutting tool workability. In this case the manganese sulphide non-metallic inclusions are intentionally formed within the metal matrix in order to make the chipping brittle) during the tool working. This role implies that the volume fraction of the inclusions has to be significant.
Sulphide dust explosions – It is an underground mining hazard involving the spontaneous combustion of airborne dust containing sulphide minerals.
Sulphide ore – It is a type of ore where the principal ore minerals contain sulphur combined with one or more metals. These ores are essential sources of several metals, including copper, lead, and zinc. Basically, a sulphide ore is a mineral deposit where a metal is chemically bonded to sulpuur.
Sulphides modification by calcium addition – Sulphur has almost unlimited solubility in liquid steel. However, solubility of sulphur in solid steel approaches zero. During solidification, sulphides precipitate in various forms at the grain boundaries producing characteristic steel defects. The chemical affinity of calcium to oxygen is higher than that of sulphur. It is estimated that for calcium to react with sulphur, the sulphur activity is to be around 19 times higher than the oxygen activity in steel, a condition which is difficult to achieve. Hence, the purpose of introducing calcium for sulphur modification is to change the sulphur release mechanism in a way such that the sulphur is bound to or precipitated around calcium containing oxide and do not deposit at grain boundaries as free sulphides during solidification. In calcium free treated steels, sulphur precipitates as small particles of manganese sulphide in the last liquid to freeze. The manganese sulphide particles are deformed to form stringers when hot rolled. However, sulphide inclusions containing calcium have a globular shape which does not deform during hot rolling.
Sulphide spheroidization – It is a stage of overheating in which sulphide inclusions are partly or completely spheroidized.
Sulphide stress cracking (SSC) – It is the brittle fracture by cracking under the combined action of tensile stress and corrosion in the presence of water and hydrogen sulphide.
Sulphide-type inclusions – In steels, nonmetallic inclusions composed essentially of manganese iron sulfide solid solutions (Fe,Mn)S. They are characterized by plasticity at hot-rolling and forging temperatures and, in the hot-worked product, appear as dove-gray elongated inclusions varying from a thread-like to oval outline.
Sulphite – It is a salt of sulphurous acid which contains the anion [(SO3)2-].
Sulpho-chlorinated lubricant – It is a lubricant containing chlorine and sulphur compounds, which react with a rubbing surface at high temperatures to form a protective film. There can be a synergistic effect, producing a faster reaction than with sulphur or chlorine additives alone.
Sulphonation – It is a chemical process which involves introducing a sulphonic acid group (-SO3H) into an organic compound, typically by replacing a hydrogen atom on the molecule with the ‘-SO3H’ group. This reaction is normally carried out by treating an organic compound with a sulphonating agent, such as concentrated sulphuric acid, oleum, or sulphur tri-oxide, and is an important step in synthesizing various industrial chemicals and derivatives.
Sulphonic acid – It is an organo-sulphur compound with the general formula R-SO3H, where ‘R’ is an organic group and ‘−SO3H’ is the sulphonyl hydroxide (or sulphonate) group. These are strong organic acids similar in acidity to inorganic acids, and their salts and derivatives are widely used in several products, e.g., dyes.
Sulphur (S) – It is a chemical element having atomic number 16. It is abundant, multivalent, and non-metallic. Under normal conditions, sulphur atoms form cyclic octatomic and molecules with the chemical formula S8. Elemental sulphur is a bright yellow, crystalline solid at room temperature. Sulphur normally occurs as sulphide and sulphate minerals. Almost all elemental sulphur is produced as a by-product of removing sulphur-containing contaminants from natural gas and petroleum. The maximum commercial use of the element is the production of sulphuric acid for sulphate and phosphate fertilizers, and other chemical processes. Almost all elemental sulphur is produced as a by-product of removing sulphur-containing contaminants from natural gas and petroleum. The maximum commercial use of the element is the production of sulphuric acid for sulphate and phosphate fertilizers, and other chemical processes.
Sulphur deposits – These are natural accumulations of elemental sulphur found in geological formations, frequently as yellow, crystalline deposits in volcanic areas, near hot springs, or within underground salt domes. They form when hydrogen sulphide gas from volcanic activity or deep sub-surface environments reacts with oxygen or is acted upon by bacteria, oxidizing to form elemental sulphur. These deposits are commercially valuable and are extracted for several uses.
Sulphur di-oxide – is the chemical compound with the formula SO2. It is a colourless gas with a pungent smell that is responsible for the odour of burnt matches It is a gas liberated during the smelting of majority of the sulphide ores. It is either converted into sulphuric acid or released into the atmosphere in the form of a gas. It is produced as a by-product of metals refining and the burning of sulphur-bearing fossil fuels. Sulphur di-oxide is somewhat toxic to humans, although only when inhaled in relatively large quantities for a period of several minutes or more.
Sulphur dome – It is an inverted container, holding a high concentration of sulphur di-oxide gas, used in die casting to cover a pot of molten magnesium to prevent burning.
Sulphur emissions – These refer to the release of sulphur compounds, mostly sulphur di-oxide (SO2) , into the atmosphere, mainly from the burning of sulphur-containing fossil fuels like coal and oil. These emissions are a significant air pollutant, contributing to environmental issues such as acid rain, which damages ecosystems, and particulate matter, which harms human health by affecting the respiratory system.
Sulphur hexa-fluoride (SF6) – It is a synthetic, colourless, odourless, and non-flammable gas used in several applications, including electrical power systems for insulation and arc quenching, and also as an etching gas in manufacturing. It is also a potent green=house gas, contributing significantly to global warming.
Sulphur hexa-fluoride circuit breaker – It is a kind of automatic circuit protection switch that breaks current in an atmosphere of pressurized sulfur hexafluoride gas to extinguish the arc.
Sulphuric acid – It is also called oil of vitriol. It is a mineral acid composed of the elements sulphur, oxygen, and hydrogen, with the molecular formula HSO4. It is a colourless, odourless, and viscous liquid which is miscible with water. Pure sulphuric acid does not occur naturally due to its strong affinity to water vapour. It is hygroscopic and readily absorbs water vapour from the air. Concentrated sulphuric acid is a strong oxidant with powerful dehydrating properties, making it highly corrosive towards other materials, from rocks to metals. Phosphorus pentoxide is a notable exception in that it is not dehydrated by sulphuric acid but, to the contrary, dehydrates sulphuric acid to sulphur trioxide. Upon addition of sulphuric acid to water, a considerable quantity of heat is released. Hence, the reverse procedure of adding water to the acid is normally avoided since the heat released can boil the solution, spraying droplets of hot acid during the process.
Sulphuric acid refining – It refers to a method of refining of the crude benzol (CB). It comprises the purification of the crude benzol and its subsequent separation into the desired commercial products. This entails chemical washing and fractional distillation. The crude benzol is washed with concentrated sulphuric acid which sulphonates the more undesirable compounds and allows easier separation and recovery of the benzene, toluene and xylene (BTX) fractions. The sulphuric acid washing removes unsaturated compounds, olefins, dienes etc. together with any pyridine and some sulphur compounds. The olefins, dienes and other unsaturated compounds are removed by the sulphuric acid, partly by polymerization and resinification, and partly by solution in the acid.
Sulphur-iodine cycle (SI cycle) – It is a thermo-chemical cycle which utilizes sulphuric acid (H2SO4) and hydrogen iodide (HI) for the production of hydrogen, characterized by specific chemical reactions, including the decomposition of sulphuric acid and the Bunsen reaction, making it suitable for integration with high-temperature nuclear reactors.
Sulphurized lubricant – It is a lubricant containing sulfur or a sulfur compound that reacts with a rubbing surface at high temperatures to form a protective film. The shear strength of the sulphide film formed on ferrous materials is lower than that of the metal but higher than that of the film formed by reaction with a chlorinated lubricant.
Sulphur oxides (SOx) – Sulphur oxides (SOx) are a group of compounds made up of sulphur (S) and O2 molecules. The most common sulphur oxide is SO2 (sulphur di-oxide). Sulphur di-oxide is a chemical compound with the formula SO2. It is a major component of SOx. Sulphur di-oxide is a gas formed from the oxidation of sulphur contained in fuel as well as from certain industrial processes which utilize sulphur-containing compounds. Anthropogenic emissions of sulphur di-oxide result almost exclusively from stationary point sources. A small fraction of SOx is emitted as primary sulphates, gaseous sulphur trioxide (SO3), and sulphuric acid (H2SO4).
Sulphur print – It is a macrographic method of examining for distribution of sulphide inclusions by placing a sheet of wet acidified photographic paper in contact with the polished sheet surface to be examined.
Sulphur vulcanization – It is a chemical process where raw rubber is heated with sulphur to form a network of sulphur cross-links between polymer chains, transforming it into a more durable and elastic material with improved strength and temperature resistance. This process improves the rubber’s hardness, elasticity, and mechanical durability by preventing polymer chains from slipping past each other when stretched.
Sumitomo top and bottom (STB) blowing process – It is a steelmaking method which combines top and bottom blowing techniques to improve refining efficiency and steel quality. It was developed by Sumitomo Metal Corporation of Japan. The Sumitomo top and bottom (STB) blowing process utilizes both top-blown oxygen for decarburization (reducing carbon content) and bottom-blown gas (like carbon di-oxide) for stirring and mixing the molten steel, as well as other impurities.
Summation sign – It is denoted by the uppercase Greek letter Sigma. It is a mathematical notation which represents the sum of a sequence of numbers or terms which follow a specific pattern. It acts as a compact shorthand, indicating that one is to add up a series of terms by taking a variable index, starting from a specified lower limit, and continuing until a specified upper limit is reached.
Sump – It is an underground excavation where water accumulates before being pumped to surface.
Sump tank – It is a reservoir, frequently a pit or underground tank, used to collect and store liquids such as water, wastewater, lubricating oil, or fuel, which is then removed or pumped out by a sump pump. These tanks are common in industrial systems for hydraulic fluid or waste oil, and in rain-water harvesting systems for water storage and reuse.
Sum peak – It is an artifact encountered during pulse pileup where two X-rays simultaneously entering the detector are counted as one X-ray, the energy of which is equal to the sum of both X-rays.
Sun checking – It is the surface deterioration in the form of cracks, checks, or crazing caused by exposure to direct or indirect sunlight.
Super-abrasives – These are exceptionally hard and abrasion-resistant synthetic materials which are used for a wide variety of abrasive or cutting applications. Synthetic diamond and cubic boron nitride (CBN) are the two super-abrasives which are used for grinding applications. Diamond is the hardest material known, and cubic boron nitride is the second hardest.
Super-abrasives and ultra-hard tool materials – The principal super-hard materials are found as phases in the boron-carbon-nitrogen-silicon family of elements. Of these, the super-hard materials of commercial interest include silicon nitride (Si3N4), silicon carbide (SiC), boron carbide (B4C), diamond, and cubic boron nitride (CBN). Silicon nitride provides the base composition for the important category of Si-AI-O-N ceramics, which are used in structural applications and as high-speed cutting tool materials. The carbides of the metalloids like boron and silicon (B4C and SiC) are also of considerable industrial significance and enjoy such diverse applications as super-hard tools and electrical resistor heating elements. These compounds are processed and used both with or without metallic binder phases. When these two metalloid carbides are used without a metallic binder phase, the resultant material most likely falls within the material group of ceramics. If silicon carbide (SiC) and boron carbide (B4C) are used with a metallic binder phase, then the resultant material is considered a cermet. Super-abrasives are synthetically produced diamond and cubic boron nitride (CBN) used in a wide variety of cutting and grinding applications.
Super-alloys – These are heat-resistant alloys based on nickel, iron-nickel, or cobalt which show high strength and resistance to surface degradation at high temperatures.
Supramor – It is an electro-magnetic flaw detection ink for the rapid detection of subcutaneous and surface flaws in ferrous metals.
Super annealing – It is an annealing cycle for heat treatable alloys which utilizes a slow, controlled, cooling rate to produce a structure with maximum ductility and the minimum tendency to natural ageing.
Super-austenitic stainless steels – These are advanced alloys with a complex chemical composition, specifically high concentrations of nickel, molybdenum, and sometimes nitrogen and copper, which provide superior resistance to different forms of corrosion, including pitting, crevice, and acid attacks, even in harsh industrial environments. Their high pitting resistance equivalent number (PREN), which is higher than 35, is a key indicator of this improved corrosion performance, setting them apart from standard austenitic stainless steels.
Super-computer – It is a computer with a substantially higher level of performance than a general-purpose machine. It is especially adapted for high intensity calculation on large data sets.
Super-conducting electric machine – It is an experimental type of generator or motor which has part of its electric circuits in the super-conducting state.
Super-conducting magnet – It is an electro-magnet which is made from coils of super-conducting wire. They are to be cooled to cryogenic temperatures during operation. In its super-conducting state, the wire has no electrical resistance and hence can conduct much larger electric currents than ordinary wire, creating intense magnetic fields. Super-conducting magnets can produce stronger magnetic fields than all but the strongest non-superconducting electro-magnets, and large super-conducting magnets can be cheaper to operate since no energy is dissipated as heat in the windings.
Super-conducting magnetic energy storage (SMES) – It is a technology which stores electrical energy in the form of a magnetic field within a super-conducting coil. This is achieved by passing direct current (DC) through a super-conducting wire, which shows virtually no electrical resistance, allowing the energy to be stored for extended periods.
Super-conducting materials – These are the substances which show the property of zero electrical resistance when cooled below a specific temperature known as the critical temperature. They also expel magnetic fields, a phenomenon called the Meissner effect, when in this superconducting state. This means electricity can flow through them without any energy loss.
Super-conducting quantum interference device (SQUID) – It is a highly sensitive magnetometer used to measure extremely small magnetic fields. It is based on the principles of super-conductivity and quantum mechanics, allowing for the detection of minute magnetic signals. Essentially, a super-conducting quantum interference device consists of a super-conducting loop interrupted by one or more Josephson junctions, which are weak links that allow current to flow through by quantum tunneling.
Super-conducting super collider (SSC) – It was a proposed particle accelerator project in Texas, designed to be the world’s largest and most energetic. It aimed to accelerate protons to extremely high energies and bring them into head-on collisions to study the fundamental building blocks of matter. The super-conducting super collider’s design relied on super-conducting magnets to bend and focus the proton beams.
Super-conductivity – It is the loss of all electrical resistance at inconveniently low temperatures. It is a property of several metals, alloys, compounds, oxides, and organic materials at temperatures near absolute zero by virtue of which their electrical resistivity vanishes and they become strongly diamagnetic.
Super-conductor-insulator-super-conductor (SIS) junction – It is a device where two super-conductors are connected by a thin insulator layer, allowing for quantum tunneling of Cooper pairs. This configuration is used in several applications like detectors and quantum computing circuits. Super-conductors are materials which show zero electrical resistance below a critical temperature, allowing electricity to flow without energy loss. Insulators, on the other hand, have a high resistance to electrical current flow. The super-conductor-insulator-super-conductor junction leverages the properties of both to create specific functionalities, such as quantum tunneling in the insulator region.
Super-cooling – It is cooling of a substance below the temperature at which a change of state ordinarily takes place without such a change of state occurring, e.g., the cooling of a liquid below its freezing point without freezing taking place. This results in a metastable state.
Super-critical boiler – It is a type of boiler which operates at pressures above the critical point of water (22.1 mega-pascals), where water directly transforms into superheated steam without a distinct phase transition. Unlike sub-critical boilers, there is no separate boiling stage. Instead, water is heated directly into superheated steam. This technology offers higher efficiency compared to sub-critical boilers because of the ability to operate at higher pressures and temperatures.
Super-critical flow – It is a type of fluid flow characterized by a Froude number higher than 1, meaning the flow velocity exceeds the speed of surface gravity waves (or wave celerity). This condition results in rapid, high-velocity, low-depth flow that is influenced mainly by inertial forces and behaves as a rapid or unstable flow. Super-critical flow is also known as torrential or shooting flow.
Super-critical fluid (SCF) – It is a substance existing at a temperature and pressure above its critical point. At this state, it has properties which are a blend of both liquids and gases. It has the low viscosity and high diffusivity of a gas, allowing it to penetrate solids, and the solvent power of a liquid, enabling it to dissolve substances. Super-critical fluids have no distinct liquid / gas surface tension, and their density can be finely tuned by adjusting temperature and pressure.
Super-critical fluid chromatography (SFC) – It is a chromatographic technique which uses a super-critical fluid, typically carbon di-oxide, as the mobile phase to separate and analyze compounds. It combines the characteristics of both gas and liquid chromatography, offering unique advantages for analyzing thermally labile or non-volatile compounds.
Super-critical water oxidation (SCWO) – It is a process where organic waste is oxidized in water that is at temperatures and pressures above its critical point (374.3 deg C and 22.12 megapascals). Under these conditions, water becomes a supercritical fluid, showing properties of both a liquid and a gas. This allows for the complete destruction of organic waste into harmless byproducts like carbon di-oxide and water.
Super duty fireclay bricks – These bricks having pyrometric core equivalent (PCE) above 33 with less than 1 % linear shrink in the 1,600 deg C reheat test, and less than 4 % loss in panel spalling test preheated at 1,650 deg C.
Super duty refractories – These refractories have pyrometric cone equivalent (PCE) value ranging from 33 to 38.
Superficial hardness test – It is also called Rockwell superficial hardness test. It is the same test as used to determine the Rockwell hardness number except that smaller minor and major loads are used. In Rockwell testing, the minor load is 10 kgf (kilogram-force), and the major load is 60 kgf, 100 kgf, or 150 kgf. In superficial Rockwell testing, the minor load is 3 kgf, and major loads are 15 kgf, 30 kgf, or 45 kgf. In both tests, the indenter can be either a diamond cone or a steel ball, depending principally on the characteristics of the material being tested.
Super-fines – It consists of the portion of a metal powder which is composed of particles smaller than a specified size, normally 10 micrometers.
Super-finishing – It is also known as micro-finishing or short-stroke honing. It is a metalworking process which refines the surface of a component to achieve an ultra-smooth, uniform finish. It involves removing the thin, amorphous layer left by previous machining processes using an abrasive stone or tape with fine grains. This process considerably reduces surface roughness, leading to improved friction, wear, noise, and heat generation. It is a low-velocity abrading process very similar to honing. However, unlike honing, superfinishing processes focus mainly on the improvement of surface finish and much less on correction of geometric errors (dimensional accuracy). It is also known as micro-honing.
Super fluxed sinter – It is the sinter in which sufficient flux is added in the sinter mix for producing slags of desired basicity in blast furnace taking also into account the acidic oxides in the coke ash in addition to the other acidic oxides in the blast furnace burden.
Super grid – It is a wide area power transmission network which allows interchange over continental distances.
Super-hard material – It is a material with a hardness value exceeding 40 giga-pascals (GPa) when measured by the Vickers hardness test. These materials are virtually incompressible solids with high electron density and high bond covalency. As a result of their unique properties, these materials are of high interest in several industrial areas including, but not limited to, abrasives, polishing and cutting tools, disc brakes, and wear-resistant and protective coatings.
Superheat – It is an increment of temperature above the melting point of a metal. It is sometimes construed to be any increment of temperature above normal casting temperatures introduced for the purpose of refining, alloying or improving fluidity.
Super heat duty refractory – It is a specialized material designed to withstand extremely high temperatures and maintain its structural integrity in those demanding environments. It is characterized by its high refractoriness, meaning it resists softening and deformation at high temperatures.
Super-heated gas – It is a gas whose temperature is above its saturation temperature (or boiling point) for a given pressure, meaning it is no longer in a saturated state and does not condense without losing the extra heat. It has absorbed more heat than was necessary to convert the substance from a liquid to a gas, ensuring only gas (no liquid droplets) enters components like a compressor.
Super-heated liquid – It is a liquid heated above its normal boiling point without undergoing vapourization. This metastable state is possible when a liquid is kept in a perfectly smooth container, free from impurities or air bubbles, which act as nucleation sites for boiling to begin. A super-heated liquid can erupt violently and explosively if disturbed by factors like vibrations, the introduction of a foreign object, or even the presence of a single impurity.
Super-heated steam – When more heat energy is added to steam that has reached saturation, and no liquid water is present to consume that energy through evaporation, the temperature of the steam increases. In this condition, steam is said to be ‘superheated’. Super-heated steam is the steam with its temperature raised above that of saturation. The temperature in excess of its saturation temperature is referred to as super-heat. When all the water is vapourized, any subsequent addition of heat raises the temperature of steam. Steam heated beyond the saturated steam level is called super-heated steam. Super-heated steam obeys gas laws.
Super-heated steam drying – Drying of lignite coal with steam is a recent process. In this process there is direct contact between lignite and superheated steam. The possibility of ignition and explosion during lignite drying process can be avoided due to the inertia of superheated steam. During the process there is no mass transfer resistance between moisture in lignite and superheated steam even though there is a high drying rate. In case of power plants using lignite coal as fuel in boiler, steam from turbine can be used as drying medium. If the latent heat of vaporization in off‐gas can be entirely recovered, the energy consumption of drying by superheated steam is only around 20 % of that dried by hot air. Hence, drying by superheated steam has energy saving potential.
Super-heater – The purpose of the superheater is to remove all moisture content from the steam by raising the temperature of the steam above its saturation point. The steam leaving the boiler is saturated, that is, it is in equilibrium with liquid water at the boiler pressure (temperature). The superheater adds energy to the exit steam of the boiler. It can be a single bank or multiple banks or tubes either in a horizontal or vertical arrangement which is suspended in the convective or radiation zone of the boiler. The added energy raises the temperature and heat content of the steam above saturation point. In the case of turbines, excessive moisture in the steam can adversely affect the efficiency and integrity of the turbine.
Super-heating – It is the heating of a substance above the temperature at which a change of state ordinarily takes place without a change of state occurring, e.g., the heating of a liquid above its boiling point without boiling taking place; this results in a meta-stable state. It is also an increment of temperature above the melting point of a metal, which is sometimes construed to be any increment of temperature above normal casting temperatures introduced for the purpose of refining, alloying, or improving fluidity.
Super-heavy elements – These elements are also known as transactinide elements. These are those with an atomic number higher than 104 (Rutherfordium), artificially produced and highly radioactive, existing only in laboratories.
Super-hetero-dyne receiver – It is a radio receiver which changes incoming frequencies to a fixed intermediate frequency for processing.
Super-lattice – It is also called ordered structure. It is a periodic structure, frequently composed of alternating layers of different materials, particularly semi-conductors, with dimensions on the nano-meter scale. These structures are designed to show unique electronic and optical properties because of the quantum mechanical effects, particularly carrier tunneling between layers. The term can also refer to other ordered nano-scale arrangements, like arrays of quantum dots or quantum wells. Super-lattice is the crystal structure of a solid solution in which the atoms of different elements seek preferred lattice positions.
Super micro-pore carbon block – It is made of calcined anthracite under high temperature and other additives by extruding, baking and processing. Typical properties are high thermal conductivity, high micro-pore porosity and good permeability which can reduce erosion to the body of blast furnace, and avoid the iron liquid erosion and permeability. Super micro-pore carbon block can meet the needs of the large blast furnaces.
Super-plastic deformation – It is a phenomenon where certain fine-grained materials, particularly metals, can be deformed to extremely large elongations (frequently 400 % or more) at high temperatures and relatively low strain rates without necking or fracture. This occurs because the material’s micro-structure facilitates uniform plastic flow, allowing it to withstand significant deformation before failure.
Super-plastic forming (SPF) – It is a strain rate sensitive sheet metal forming process which uses characteristics of materials showing high tensile elongation. During super-plastic forming, gas pressure is imposed on a super-plastic sheet, causing the material to form into the die configuration.
Super-plastic forming / diffusion bonding (SPF/DB) – It is a manufacturing process which combines superplastic forming (a metal forming process) with diffusion bonding (a joining process) to create complex, hollow structures. It utilizes the material’s super-plasticity to form parts, then diffusion bonding to join multiple layers together, resulting in lightweight and strong components.
Super-plasticity – It is the ability of certain metals (most notably aluminum-base and titanium-base alloys) to develop extremely high tensile elongations at high temperatures and under controlled rates of deformation.
Super-plasticizers – These are admixtures materials for concrete which are made from organic sulphonates. Their use enables the reduction of the water content in concretes substantially while at the same time increasing their slumps. Although superplasticizers can also be used to keep water-cement ratios constant while using less cement, they are more commonly used to produce workable concretes with considerably higher strengths while using the same quantity of cement. A relatively new product, self-consolidating concrete, uses superplasticizers and modifications in mix designs to produce an extremely workable mix that requires no vibration, even for the most congested placement situations.
Super-position theorem – It is the useful property of a system where the response to the sum is the sum of the responses.
Super-saturated – It is a metastable solution in which the dissolved material exceeds the quantity which the solvent can hold in normal equilibrium at the temperature and other conditions that prevail.
Super saturated steam – The steam having lesser temperature and greater density with respect to the steam table values for a particular saturation pressure is called super saturated steam. This condition is obtained when it is cooled by its own expansion in a nozzle. It is very unstable and the steam soon resumes the saturated condition.
Supersonic reflectoscope – It is an instrument for sending, receiving, and measuring sound waves over 20,000 cycles per second.
Supersonic flow – It is a fluid flow where the speed of the fluid is higher than the speed of sound in that fluid, frequently characterized by the formation of shock waves. It refers to the high-speed flow of gas around a body where shock waves are formed, resulting in low drag forces. In this type of flow, the body is to be long and pointed at both ends with small angles to minimize drag.
Supersonic speed – It refers to the speed of an object which is faster than the speed of sound in a given medium, typically air. This speed is measured in Mach, where Mach 1 is equivalent to the speed of sound. At sea level in dry air at 20 deg C, the speed of sound is around 343.2 meters per second, so any object exceeding this speed is traveling supersonically.
Super stainless steel – It consists of stainless-steel alloys with significant additions of chromium, nickel, molybdenum, or copper. Super stainless steel is used in chemical processing, petroleum refining, marine, heat treating, pollution, and waste control industries where there are requirements for extra corrosion protection, strength, or heat resistance.
Super stone finish – This surface finish is rough grind finish. In this type of finish the surface roughness (Ra) is aimed at 0.6 micro-meters.
Super sulphated cement – It is produced by grinding together a mixture of 80 % to 85 % of the granulated slag, 10 % to 15 % of the hard burnt gypsum, and 5 % of the portland cement clinker. This cement is high sulphate resistant. Because of this property, it is used for the foundations where chemically aggressive conditions exist.
Supervised area – It is an area which has radiation and contamination present at levels below controlled areas. Access to such an area is limited by the licensee or responsible organization.
Supervisors – Supervisors are leaders for their team. They play very important role in the organizational functioning. They are persons who are in charge of, and coordinates the activities of a group of employees engaged in related activities within a unit of an organization. They are front-line managers and are responsible for getting the non-executive employees to carry out the plans and policies set by the management. Supervisors are also sometimes being called as front-line supervisors since they are the first link between the management and the non-executive employees. Supervisors plan, direct, motivate, and monitor the work of non-executive employees at the operational level of the organization. Supervisors are the first-level executives, since they have only non-executive employees reporting to them. Supervisors can also be second-level supervisors when they supervise a combination of other supervisors and non- executive employees.
Supervisory control – It is a higher-level control system which monitors, coordinates, and adjusts lower-level control systems or processes to optimize overall performance. It can be human-centered, where an operator provides commands to a computer, or computer-based, like a supervisory control and data acquisition (SCADA) system, which collects data and allows for remote monitoring and control of distributed hardware. Key aspects include real-time data collection, integration of multiple controllers, and providing a comprehensive overview for better decision-making and efficiency in complex systems.
Supervisory control and data acquisition (SCADA) – It is a control system architecture comprising computers, networked data communications and graphical user interfaces for high-level supervision of machines and processes. It also covers sensors and other devices, such as programmable logic controllers, which interface with process plant or machinery. The operator interfaces which enable monitoring and the issuing of process commands, such as controller setpoint changes, are handled through the supervisory control and data acquisition computer system. The subordinated operations, e.g., the real-time control logic or controller calculations, are performed by networked modules connected to the field sensors and actuators.
Supplemental operations– These are also called secondary operations. These are additional processes performed on sintered parts to improve their dimensional accuracy, surface finish, or to add specific features which cannot be easily achieved through the initial powder compacting and sintering steps. These operations can be broadly categorized as traditional machining techniques (turning, milling, grinding, and tapping etc.) or powder metallurgy improving techniques (sizing, deburring, and plating etc.).
Supplier base – It consists of the organizational overall supply network which includes all the current suppliers an organization actively manages for purchasing parts, materials, and services to support its operations. It serves as the foundation for the organizational procurement processes and includes long-term strategic partners as well as minor or potential suppliers. Effective management of the supply base is crucial for ensuring quality, optimizing costs, and maintaining supply chain efficiency.
Supplier evaluation and assessment – It is the systematic process of analyzing potential and current suppliers to determine their ability to meet the organization’s needs, goals, and risks through quantitative and qualitative criteria. It is an essential task for procurement teams and involves assessing suppliers before signing contracts to choose the best one. Supplier evaluation also includes measuring the performance of present vendors to identify and eliminate risks. The aim is to develop a list of high-performing suppliers, mitigate supply chain risks, reduce costs, and improve overall business performance. This process uses tools like questionnaires, scorecards, financial analysis, and site visits to measure and monitor suppliers against criteria such as quality, delivery, cost, financial stability, and corporate social responsibility.
Supplier relationship management (SRM) – It is a comprehensive approach to managing interactions with suppliers, aiming to optimize value through strategic partnerships and collaborative relationships. It goes beyond simple transactions, focusing on building mutually beneficial relationships to improve innovation, reduce risks, and achieve competitive advantages.
Supply air – It is the conditioned air which is delivered to the spaces or zones within a building. This air is typically heated, cooled, or dehumidified by the heating, ventilation, and air-conditioning (HVAC) system’s air handling unit (AHU) or fan coil unit (FCU). The conditioned supply air is then distributed through a network of ducts or air distribution channels and exits into rooms through diffusers, grilles, or registers.
Supply chain – It is a complex logistics system which consists of facilities that convert raw materials into finished products and distribute them to end consumers or end customers, while supply chain management deals with the flow of goods in distribution channels within the supply chain in the most efficient manner. In sophisticated supply chain systems, used products can re-enter the supply chain at any point where residual value is recyclable. Supply chains link value chains. Suppliers in a supply chain are frequently ranked by ‘tier’, with first-tier suppliers supplying directly to the client, second-tier suppliers supplying to the first tier, and so on.
Supply chain management (SCM) – A supply chain is composed of all the organizations which are involved in the design, production, and delivery of a product to market. Supply chain management is the coordination of production, inventory, location, and transportation among the participants in a supply chain to achieve the best mix of responsiveness and efficiency for the market being served. The goal of supply chain management is to increase sales of goods and services to the final, end use customer while at the same time reduce both inventory and operating expenses. Supply chain management integrates several activities of the organization ranging from manufacturing operations, purchasing, transportation, and physical distribution into a unified programmed action. Successful supply chain management coordinates and integrates all of these activities into a seamless process. It embraces and links all of the partners in the chain. In addition to the departments within the organization, these partners include suppliers, customers, transporters, third-party organizations, and information systems providers.
Supply chain (nuclear) – It consists of the system of organizations, people, technology, activities, information and resources involved in moving nuclear energy from generator / supplier to customer.
Supply chain risk management (SCRM) – It is a strategic process which involves identifying, assessing, and mitigating potential disruptions within the organizational supply chain. It aims to minimize the negative impact of risks on the organization’s operations, financial performance, and reputation. This proactive approach helps the organization to stay ahead of potential disruptions, ensuring the smooth flow of goods and services from suppliers to customers.
Supply frequency – It is the rate at which alternating current (AC) voltage and current change direction per second, measured in hertz (Hz). It represents the number of full cycles an alternating current waveform completes in one second. This frequency is established at the generation source, typically at 50 hertz or 60 hertz for power systems, and is crucial for operating electronic devices correctly and for ensuring the synchronism of electrical equipment with a main system.
Supply management – It refers to the process of acquiring and managing the resources, materials, and suppliers an organization needs to operate. This includes everything from purchasing goods and services to managing inventory and logistics. Essentially, it is about ensuring an organization has what it needs to operate efficiently and profitably.
Supply voltage – It is the electrical potential, measured in volts, provided by a power source (like a battery or the mains) to operate an electronic device or circuit. It represents the constant electrical ‘pressure’ needed to drive the current which enables the device’s functionality. This voltage level determines the operational limits and performance characteristics of the device.
Support – It is the systematic arrangement of structural elements dedicated to preserving the elevation or alignment of conveyors. Supports can manifest as hangers, floor supports, or brackets, offering both stationary and portable configurations. Periodic inspections are crucial to uphold their effectiveness and ensure the overall stability of the conveyor system.
Support function – It is a department or activity within an organization which provides essential services to enable the core operational functions to operate effectively, rather than directly generating revenue or producing the main product / service. Common examples include human resource management, information technology (IT), finance and accounting, and legal departments etc., which offer critical infrastructure, expertise, and processes which ensure overall operational efficiency and success.
Supporting electrode – It is an electrode, other than a self-electrode, on which the sample is supported during spectro-chemical analysis.
Supporting process – It is an internal organizational process which facilitates and enables the core processes of an organization, such as producing a product or delivering a service. While supporting processes do not directly generate revenue or provide value to external customers, they are crucial for maintaining efficiency, managing resources, ensuring compliance, and allowing core processes to function effectively.
Supporting structure – It is also called structural support. It is a component or system which holds a structure in place, resists applied loads (like gravity, wind, or seismic forces), and transfers these forces safely to the foundation. These supports provide the necessary strength and stiffness to prevent collapse, ensuring the stability, safety, and functionality of engineered system.
Support pins – These are rods or pins of precise length which are used to support the overhang of irregularly shaped punches in metal forming presses.
Support plate – It is a plate which supports a draw ring or draw plate in a sheet metal forming press. It also serves as a spacer. It is also called draw plate and draw ring.
Support rolls – These rolls refer to rollers in continuous casting machine which provide support to the solidified metal strand (or billet, bloom, or slab) as it exits the mould and moves through the cooling and shaping stages of the casting process. These rolls prevent the strand from sagging, bulging, or deforming, ensuring a consistent and uniform shape.
Suppression – It means the intentional reduction or elimination of an unwanted signal, phenomenon, or effect to achieve acceptable levels or prevent adverse impacts. This concept applies broadly, such as in fire suppression systems that control or extinguish fires, noise suppression to reduce unwanted electrical interference, or arc suppression to minimize energy from electric arcs in electrical contacts.
Suppression system – It is an integrated set of equipment and materials designed to detect, control, and extinguish fires by preventing their spread or growth, thereby protecting people, property, and assets. These systems can be active (automatic) or passive and use several agents, such as water, foam, or chemical compounds, released through integrated detection and alarm components like heat or smoke sensors to respond to a fire threat.
Surface acoustic wave (SAW) – It is a mechanical wave which propagates along the surface of a solid material. It is characterized by an amplitude which decays exponentially with depth into the material, meaning the wave’s energy is mainly concentrated near the surface. Surface acoustic waves are frequently generated and detected using piezo-electric materials and inter-digital transducers (IDTs).
Surface activation – It is a surface modification process which alters a material’s surface chemistry, physical structure, or energy to improve properties like adhesion, wettability, and reactivity for specific applications. Normal methods include plasma treatment, etching, and introducing functional groups to create a surface more receptive to bonding, painting, varnishing, or other manufacturing processes.
Surface active agent – It is a substance which affects markedly the interfacial or surface tension of solutions even when present in very low concentrations.
Surface aeration – It is the process of increasing dissolved oxygen in a liquid, normally water, by agitating its surface using mechanical devices or natural processes like high-velocity flow. This agitation, or splashing, creates more surface area for air to mix with the water, promoting gas exchange, and helps circulate the liquid to distribute oxygen and suspend micro-organisms. Surface aeration is crucial in waste-water treatment to support aerobic micro-organisms which break down organic matter, as well as in ponds and lakes to maintain healthy oxygen levels for aquatic life and to help remove soluble metals like iron and manganese through oxidation.
Surface alterations – These are Irregularities or changes on the surface of a material because of the machining or grinding operations. The types of surface alterations associated with metal removal practices include mechanical (e.g., plastic deformation, hardness variations, and cracks etc.), metallurgical (e.g., phase transformations, twinning, recrystallization, and untempered or over-tempered martensite), chemical (e.g., inter-granular attack, embrittlement, and pitting), thermal (heat-affected zone, recast, or redeposited metal, and resolidified material), and electrical surface alterations (conductivity change or resistive heating).
Surface area (A) – It is a measure of the total area of a solid object which the surface of the object occupies. It is the total extent of the outer surfaces of a three-dimensional object, encompassing all its faces and curved surfaces. It is a fundamental concept used in designing and analyzing objects, determining material needs for structures, optimizing processes like heat transfer, and evaluating factors like stress distribution and reaction rates. Engineers calculate surface area using specific geometric formulas to optimize designs, ensure efficient material usage, and understand how surfaces interact with their environment.
Surface asperity – It is a microscopic, high-spot projection or bump on a real-world surface which causes two contacting surfaces to touch only at a very small number of localized points. These imperfections are crucial in the field of tribology (the study of friction, wear, and lubrication) since they contribute to friction, wear, and material deformation when surfaces move against each other, even when they appear smooth at a macroscopic level.
Surface bloom – It is a general term for any surface discolouration caused by thermal treatment or from exposure to moist atmospheres.
Surface blow-off – It is the removal of water, foam, etc. from the surface at the water level in a boiler.
Surface checking – It is also called checks. It consists of several, very fine cracks in a coating or at the surface of a metal part. It can appear during processing or during service and are very frequently associated with thermal treatment or thermal cycling. It is also minute cracks in the surface of a casting caused by unequal expansion or contraction during cooling.
Surface coating – It is the application of a layer of material to a substrate to modify its surface properties, improving performance, durability, and appearance without altering the bulk material. These coatings can provide protection against corrosion and wear, reduce friction, improve adhesion, and add decorative or functional characteristics, such as electrical, thermal, or optical properties. Common applications include automotive and construction, utilizing techniques like painting, plating, and vapour deposition to achieve specific functional or aesthetic goals for a product.
Surface condition – It refers to the physical characteristics and properties of a material’s outermost layer, encompassing its texture, finish, and any contaminants or imperfections present. This can include features like smoothness, roughness, brightness, and reflectivity, which can be affected by manufacturing processes, wear, or environmental factors. For example, a smooth, glossy surface has a different condition than a rough, matte surface, or a surface with rust.
Surface contact points – These are also called necks. These are the areas where individual powder particles come into contact and form the initial bond during sintering. These contact points are crucial for densification and the overall strength of the final product.
Surface contamination – It refers to any undesired substance, such as particles, molecules, or biological agents, which adheres to or deposits onto a material’s surface. This presence of impurities can drastically alter the material’s intrinsic properties, affecting its performance, durability, and safety by negatively impacting adhesion, corrosion resistance, catalytic activity, and overall functionality.
Surface corrosion – It is the irreversible chemical or electro-chemical degradation of a material’s surface because of the interaction with its environment, frequently forming a more stable compound like an oxide, hydroxide, or sulphide. This process involves a gradual deterioration and loss of material properties, which can affect the structural integrity and service life of components, with common examples including the rusting of iron or the formation of green films on copper.
Surface crack – It is a crack which is open to the inside of a component and does not penetrate through it. A surface crack refers to a crack line in a 2D case or a crack surface in a 3D case that can be mapped to a minimum energy surface. Surface or sub-surface cracks are formed around some pre-existing defects and flaws induced in a mechanical component during service.
Surface crazing – It is a network of hairline cracks confined to the surface of a coherent refractory.
Surface damage – In tribology, it is damage to a solid surface resulting from mechanical contact with another substance, surface, or surfaces moving relatively to it and involving the displacement or removal of material. In certain contexts, wear is a form of surface damage in which material is progressively removed. In another context, surface damage involves a deterioration of function of a solid surface even though there is no material loss from that surface. Surface damage can hence precede wear.
Surface defects – These defects are restricted to surface or near surface regions. They are both of process related origin and metallurgical origin. Surface defects are normally characterized as (i) deformation or forming process induced, (ii) environment induced, (iii) coating related, and (iv) induced by solidification structure. Examples of surface defects are (i) lap which appears as seam across the surface of the metal and occurs when a corner or fin is folded over and rolled but not welded into the metal, (ii) mill shearing which occurs as a feather-like lap, (iii) rolled in scale which occurs when mill scale is rolled into the steel, (iv) scabs which are long patches of loose metal that have been rolled into the surface of the steel, (v) seams which are open, broken lines that run along the length of the rolled steel and caused by the presence of scale as well as due to pass roughness of roughing mill, and (vi) slivers which are prominent surface ruptures.
Surface deformation – It refers to a change in the shape or size of an object’s outer boundary because of the external forces, which can involve elastic (temporary) or plastic (permanent) changes. This process results in a new surface topography and can occur in different engineering fields, such as mechanical deformation of metals, impacting properties like stress distribution, material properties, and even biological interactions.
Surface diffusion – It refers to the movement of atoms or molecules across the surface of a powder particle or a sintered compact. It is a crucial mechanism in processes like sintering, where it facilitates the densification and shaping of materials from powders. Essentially, it is the migration of atoms along the surface to find low-energy sites and facilitate bonding between particles.
Surface distress – In bearings and gears, it is damage to the contacting surfaces which occurs through intermittent solid contact involving some degree of sliding and / or surface fatigue. Surface distress can occur in several forms depending on the conditions under which the bearing or gear has been operated and on the nature of the interaction between the contacting surfaces.
Surface engineering – It is the science and technology of modifying the surface properties of materials to improve their performance, durability, and functionality. It involves techniques which alter the surface characteristics of a material, such as its composition, microstructure, and topography, to achieve specific desired properties, such as increased wear resistance, corrosion resistance, improved adhesion, or improved bio-compatibility.
Surface-enhanced Raman spectroscopy (SERS) – It is a technique which considerably amplifies Raman scattering signals from molecules near nanostructured metal surfaces. This enhancement is achieved through the excitation of localized surface plasmons (LSPs), which amplify the electromagnetic field at the surface, making it easier to detect molecular vibrations. Surface-enhanced Raman spectroscopy is highly sensitive and can detect molecules at extremely low concentrations, making it useful in several fields like materials science, and forensics.
Surface expulsion – It is the expulsion occurring at an electrode-to-work-piece contact rather than at the faying surface.
Surface film – It refers to a thin layer of material (like an oxide or adsorbed organic compound) which forms on the surface of metal powder particles. These films can interfere with the bonding process during sintering, affecting the final properties of the powder metallurgy product.
Surface finish – It is the geometric irregularities in the surface of a solid material. Measurement of surface finish does not include inherent structural irregularities unless these are the characteristics being measured. It is also the condition of a surface as a result of a final treatment.
Surface finishing – It is the process of applying a surface treatment to clean the surface, to improve its appearance, or to give it a special property such as corrosion or wear resistance.
Surface force apparatus (SFA) – It is a scientific instrument which used to precisely measure the forces and distances between two surfaces, typically in contact or separated by a thin film. It allows the study of interfacial phenomena at the molecular level, including van der Waals forces, electrostatic forces, and other interactions. The surface force apparatus can measure forces with a sensitivity of a few nano-newtons (nN) and resolve distances down to around 1 Angstrom (0.1 nanos-meter).
Surface friction – It is the resistive force which acts at the interface between two surfaces in contact, opposing their relative motion. This force is a result of the interlocking of surface irregularities and attractive molecular forces, needing energy to shear these bonds or overcome the rougher surface plowing through the softer surface. Friction can also refer to the phenomenon of fluid layers sliding against each other or material elements within a solid.
Surface grinding – It means producing a plane surface by grinding.
Surface hardening – It is a generic term covering several processes applicable to a suitable ferrous alloy which produces, by quench hardening only, a surface layer which is harder or more wear resistant than the core. There is no significant alteration of the chemical composition of the surface layer. The processes normally used are carbonitriding, carburizing, induction hardening, flame hardening, nitriding, and nitro-carburizing. Use of the applicable specific process name is preferred.
Surface hardness test – It is a method to measure a material’s resistance to permanent deformation, such as indentation, scratching, or compression. This is typically done by pressing a known, harder object called an indenter into the surface of the material being tested under a prescribed force. The resulting impression’s depth or size, or the recovery of the material from the indentation, is then measured to determine the material’s hardness.
Surface integrity – It is a technology which involves the specification and manufacture of unimpaired or improved surfaces through the control of the several possible alterations produced in a surface layer during manufacture. Surface integrity is achieved by the proper selection and control of manufacturing processes and the ability to estimate their effects on the significant engineering properties of work materials.
Surface layer activation – It refers to the process of modifying the surface properties of a material, typically to enhance its reactivity, adhesion, or other desirable characteristics. This can be achieved through various methods, including introducing chemical groups, physically altering the surface (e.g., roughening or etching), or employing techniques like plasma treatment.
Surface preparation – It refers to the process of treating the surface of a material before applying coatings, adhesives, or undergoing processes like welding or assembly. It involves cleaning, preparing, and frequently roughening the surface to improve adhesion and ensure optimal performance of subsequent processes. This can involve mechanical methods like abrasive blasting or chemical treatments. It consists of physical and / or chemical preparation of an adherend to make it suitable for adhesive bonding.
Surface protection air liquid (SPAL) – It is the use of liquid argon, liquid nitrogen, or carbon di-oxide snow to minimize the reaction of air and molten metal which normally occurs in an induction furnace. The liquid or snow is fed onto the surface of the molten metal where it vapourizes, displacing the air hence reducing slag and oxygen levels.
Surface tear – It is minute surface cracks on rolled products which can be caused by insufficient ingot scalping.
Surface texture – It is the roughness, waviness, lay or other characteristics of the surface of a part.
Surface topography – It is the fine-scale features of a surface as defined by the size and distribution of asperities. Surface topography is measured by surface roughness and the direction of surface features (lay).
Surface treatment – It refers to the processes applied to the surface of a material to modify its properties, frequently for functional or decorative purposes. This can involve adding coatings, hardening the surface, or altering its chemical composition to improve resistance to corrosion, wear, or other environmental factors. In composites, it a material (size or finish) applied to fibrous material during the forming operation or in subsequent processes. For carbon fibre surface treatment, it is the process used to improve bonding capability of fibre to resin.
Surfacing – It is the application by welding, brazing, or thermal spraying of a layer or layers of material to a surface to get desired the properties or dimensions, as opposed to making a joint.
Surfacing mat – It is a very thin mat, normally 180 micrometers to 510 micrometers thick, of highly filamentized fibre-glass, used mainly to produce a smooth surface on a reinforced plastic laminate, or for precise machining or grinding.
Surfacing material – It is the material which is applied to a base metal or substrate during surfacing.
Surfacing metal – It is the metal which is applied to a base metal or substrate during surfacing.
Surfacing weld – It is a weld applied to a surface, as opposed to making a joint, to get desired properties or dimensions.
Surface meter per minute (m/min) – It is a unit of measurement for cutting speed, specifically the linear distance a cutting tool travels across the surface of a work-piece per minute. It is a crucial factor in machining, impacting tool life, surface finish, and overall productivity.
Surface modification – It is the alteration of surface composition or structure by the use of energy or particle beams. Two types of surface modification methods normally used are ion implantation and laser surface processing. The alteration of surface composition or structure by the use of energy or particle beams. Elements can be added to influence the surface characteristics of the substrate by the formation of alloys, metastable alloys or phases, or amorphous layers. Surface-modified layers are distinguished from conversion or coating layers by their greater similarity to metallurgical alloying versus chemically reacted, adhered, or physically bonded layers. However, surface structures are produced which differ significantly from those obtained by conventional metallurgical processes. This latter characteristic further distinguishes surface modification from other conventional processes, such as amalgamation or thermal diffusion. Two types of surface modification methods normally used are ion implantation and laser surface processing.
Surface moisture – It is also known as external moisture. The moisture adheres to the surface of coal particulates or in the bigger capillary cavities. It is the moisture, which can be removed by the coal drying in air at ambient temperature (around 25 deg C). It depends on water conditions in deposit.
Surface morphology – It is the study of the physical features and structure of a material’s surface, which can show different forms such as porous or dense morphologies, depending on the material and coating method used.
Surface permeability – It defines a material’s property to allow fluids (like water) or particles to pass through its surface. This ability depends on the material’s porous structure, which contains inter-connected voids or pores. The permeability of a surface can also refer to the flow of molecules through a capillary membrane.
Surface preparation – It refers to the processes used to clean and modify the surface of a metal before applying coatings, adhesives, or undergoing other operations. This process is crucial for ensuring proper adhesion, corrosion resistance, and overall durability of the final product.
Surface processing – It refers to the range of industrial techniques used to alter or improve a material’s surface to improve its properties, such as wear resistance, corrosion resistance, appearance, and adhesion. These processes can involve adding layers of material (coating or alloying), removing material, reshaping the surface, or modifying its chemical or physical characteristics to meet specific performance requirements.
Surface resistance – It is the measure of a material’s opposition to electrical current flow along its surface. It is frequently expressed as the ratio of applied voltage to the current flowing between two electrodes on the surface, measured in ohms. A related concept, sheet resistance, is a more fundamental property for thin films, representing the resistance of a thin square of material and being independent of the square’s size.
Surface resistivity – It is the resistance to leakage current along the surface of an insulating material. It is a measure of a material’s inherent electrical resistance along its surface. It is expressed in ohms per square and represents the resistance between two opposite sides of a square of material. This measurement helps determine how well a material resists the flow of current along its surface.
Surface roughness – These are fine irregularities in the surface texture of a material, normally including those resulting from the inherent action of the production process. Surface roughness is normally reported as the arithmetic roughness average, ‘Ra’, and is given in micrometers.
Surface run-off – It is the water which travels over the soil surface to the nearest surface stream or other surface water on land depression.
Surface temperature – It refers to the temperature of the outermost layer of an object or material. It is the temperature the people feel if they touch the surface of something, and it can vary depending on factors like the object’s material, time of day, and weather conditions.
Surface tension – It is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension is what allows objects with a higher density than water such as razor blades and insects to float on a water surface without becoming even partly submerged. At liquid-air interfaces, surface tension results from the higher attraction of liquid molecules to each other (because of the cohesion) than to the molecules in the air (because of the adhesion). There are two main mechanisms in play. One is an inward force on the surface molecules causing the liquid to contract. Second is a tangential force parallel to the surface of the liquid. This tangential force is normally referred to as the surface tension.
Surface texture – It is the roughness, waviness, lay, and flaws associated with a surface.
Surface topography – It refers to the physical features and texture geometry of a surface, including its roughness, waviness, and overall shape. It describes the small deviations of a surface from being perfectly flat, characterized by the height differences which form peaks and valleys. Surface topography is important since it influences substantially a material’s function, such as its ability to be lubricated, resist wear and corrosion, and interact with other surfaces or fluids etc.
Surface void – It is a void which is located at the surface of a material and is a consequence of processing, i.e., a surface reaction layer, as distinguished from a volume distributed flaw such as a pore or inclusion.
Surface water – It consists of water bodies such as lakes, ponds, wetlands, rivers, and streams, as well as groundwater with a direct and immediate hydrological connection to surface water.
Surfacing – It is the deposition of filler metal (material) on a base metal (substrate) to get desired properties or dimensions, as opposed to making a joint.
Surfacing weld – It is a type of weld composed of one or more stringer or weave beads deposited on an unbroken surface to get desired properties or dimensions.
Surfactant – It is a chemical substance which is characterized by a strong tendency to form adsorbed interfacial films when in solution, emulsion, or suspension, hence producing effects such as low surface tension, penetration, boundary lubrication, wetting, and dispersing. It is a substance which lowers the surface tension of the medium in which it is dissolved, and / or the interfacial tension with other phases, and, accordingly, is positively adsorbed at the liquid–vapour and / or other interfaces.
Surge – It is the sudden displacement or movement of water in a closed vessel or drum.
Surge arrester – It is a device intended to absorb brief transient over voltages to protect machines or apparatus.
Surge protection – It is the measures taken to protect machines and apparatus from transient over voltages.
Surveying – It is the science and art of determining the relative positions of points on or near the earth’s surface, including their elevations, and representing them on a plan or map. It involves making measurements of distances, directions, and elevations, and then using these measurements to create a representation of the area surveyed, which is necessary for planning and executing different engineering projects.
Surveyor – It is a highly skilled professional who measures and maps land, structures, and other three-dimensional objects, using mathematics, physics, and specialized technology to accurately determine the position of points, distances, and angles. They interpret this spatial information for planning and administration of projects like land development, construction, water infrastructure, and mapping.
Survival analysis – It is the analysis of time-to- event data, i.e., the length of time until an event occurs to subjects. The most popular multi-variable technique, Cox regression, is a model for the log of the hazard of the event.
Survival function – It is the probability of surviving to a particular point in time without experiencing the event of interest. This changes over time and is hence a function of time.
Suspended idlers – These are also called garland idlers. These are load-bearing rollers which are hung from the conveyor frame. They are designed to support the conveyor belt and its load, particularly in areas where the conveyor alignment needs to be modified frequently, like in coal mining or open-cut applications. These idlers are available as two-roll, three-roll, or five-roll units. These idlers are also sometimes referred to as catenary idlers. Normally, two-roll units are utilized as return idlers and serve to aid in belt training due to the trough which is formed. Three-roll and five-roll units are used as carrying or impact units. Rubber discs can be utilized on three-roll units to provide additional cushioning. Five-roll units do not use rubber discs. All garland idlers are suspended from the conveyor framework by means of various devices such as hooks or chains. The suspended design aids in belt alignment and handles large, irregular lumps because of the flexible connections and available vertical move. Five-roll designs offer a deep trough configuration and greater load capacities than conventional three-roll units. Suspended idlers can be furnished with quick release suspensions which allow the unit to be lowered away from belt contact in case of roll failure. Suspended design idlers can be utilized on rigid frame or wire rope supported conveyor systems.
Suspended particulate matter (SPM) – It is also known as particulate matter (PM). It refers to tiny solid or liquid particles suspended in the air, which can be hazardous to human health and the environment.
Suspended pollutants – These are frequently referred to as particulate matter (PM). These are microscopic solid or liquid particles suspended in the air. These particles can be natural, like dust and pollen, or anthropogenic, like smoke from combustion and industrial activities. The smaller the particles, the more hazardous they can be to human health because they can penetrate deeper into the respiratory system.
Suspended solids – These are solid particles which are not dissolved in water but remain in suspension, either as a colloid or due to water movement. They can include a variety of materials like sediment, silt, sand, organic matter, and even pollutants which have attached to the particles. Suspended solids are an important indicator of water quality and can impact factors like turbidity and the health of aquatic ecosystems. Suspended solids are also undissolved solids in boiler water.
Suspended solids and sediments – These are pollutants (substances, particles and chemicals) which do not easily dissolve in water. These materials are called particulate matter. These are solids in water which can be trapped by a filter. These solids can include a wide variety of materials. These comprise of silt, sand, minerals, ash, and flue dust recovered from various gas cleaning units in the plants. These appear in the water as fine suspended solids. High concentrations of suspended solids can cause many problems. Some suspended pollutants later settle under the water body. This can lead to the siltation, reduces storage capacities of reservoirs. Presence of suspended solids can block the sunlight penetration in the water, which is required for the photosynthesis by bottom vegetation. This can harm and even kill aquatic organisms which live at the bottom of water bodies. Deposition of the solids in the calm stretches of the stream can impair the normal aquatic life and affect the diversity of the aquatic ecosystem. If the deposited solids are organic in nature, they will undergo decomposition leading to development of anaerobic conditions. Finer suspended solids can injure the gills of fishes and cause asphyxiation.
Suspended tray conveyor – It is also known as ‘swing-tray conveyor’. These conveyors consist of two strands of chains between which are pivot mounted a series of trays to carry in-process movement of various unit loads (forged components, boxes etc.) along complex contours comprising horizontal and vertical paths in one vertical plane. As the trays are pivot mounted from the links of the chains, the trays along with their loads always remain suspended vertically irrespective of the path of the chain. Suspended tray conveyors are loaded on vertical sections manually or automatically by specially designed loading devices. These conveyors are particularly used for raising / lowering of loads between floors, convey materials between processing equipment, carry loads without transfer between inter-linked horizontal and vertical sections. The conveyor can be used for carrying load through processing stations like drying, and pickling chambers etc. The design of the trays is adapted to the requirements of loads and method of loading / unloading. The trays can be flat or curved. When the trays are made of steel plates in the shape of buckets for carrying powdered or granular bulk load, the particular conveyor is called ‘pivoted bucket conveyor’. The bulk material is fed into the buckets on the lower horizontal section and carried through various sections without transfers, and hence is not crushed en-route. The pivoted buckets are discharged at the upper horizontal section automatically by tippers or dischargers. The buckets are fitted with projecting curved cams or guide rollers, which on coming in contact with the arms of tippers, tip the buckets. Pivoted bucket conveyors are used in power plants in carrying coal and ashes, in cement mills, ceramic industry, and stone crushing plants etc.
Suspension – It is a heterogeneous mixture which contains solid particles which are sufficiently large for sedimentation to occur, by which such particles separate from and settle out of the fluid over time if left undisturbed. In a suspension, the solute does not dissolve but remains dispersed or suspended throughout the fluid solvent only transiently and with mechanical agitation. Suspension is also the system of tires, tire air, springs, shock absorbers and linkages which connects a vehicle to its wheels and allows relative motion between the two. Suspension systems are to support both road holding / handling and ride quality, which are at odds with each other. The tuning of suspensions involves finding the right compromise. The suspension is crucial for maintaining consistent contact between the road wheel and the road surface, as all forces exerted on the vehicle by the road or ground are transmitted through the tires’ contact patches. The suspension also protects the vehicle itself and any cargo or luggage from damage and wear. The design of front and rear suspension of an automobile can be different.
Suspension based ironmaking – Suspension based ironmaking is also known as ‘flash ironmaking technology’. This process begins with the ultrafine grinding of low-grade iron ore to produce iron ore concentrate. The iron ore is to be ground to particles of less than 100 micrometers in diameter. The ultra-fines are then reduced using hydrogen in a high-temperature ‘flash’ reactor for just a few seconds, directly producing iron once carbon is added. The iron ore concentrate can also be pre-reduced at a lower temperature in a separate reactor before being added to the flash reactor.
Suspension bridge – is a type of bridge in which the deck (the load-bearing portion) is hung below suspension cables on vertical suspenders.
Suspension cable – It is a main load-carrying member in a suspension bridge, made of high-strength steel, which is suspended between towers and supports the weight of the bridge deck through vertical suspenders.
Suspension flow – It is a type of flow where solid particles are dispersed within a fluid, showing several patterns such as fully suspended flow, two-layer flow with a moving bed, and three-layer flow with a stationary bed. These patterns are characterized by the distribution and concentration of solid particles throughout the flow.
Sustainable business models – These are defined as frameworks which create competitive advantage through superior customer value while contributing to sustainable development for both the organization and society. They incorporate a systems perspective, include a wide range of stake-holders, and consider environmental and social impacts as key factors in their operations.
Sustainability – It is a social goal for people to co-exist on earth over a long period of time. Definitions of this term are disputed and have varied with literature, context, and time. Sustainability normally has three dimensions (or pillars): environmental, economic, and social. Several definitions emphasize the environmental dimension. This can include addressing key environmental problems, including climate change and bio-diversity loss. The idea of sustainability can guide decisions at the global, national, organizational, and individual levels. A related concept is that of sustainable development, and the terms are frequently used to mean the same thing.
Sustainability engineering – It is an approach to engineering which focuses on designing and implementing solutions that minimize environmental impact and resource depletion, while also considering social and economic factors. It aims to meet the needs of the present without compromising the ability of future generations to meet their own. Basically, it is about creating a balance between environmental protection, social responsibility, and economic viability.
Sustainable development – It consists of industrial development which does not detract from the potential of the natural environment to provide benefits to future generations.
Sustainable energy – It is the energy which meets the present needs for power without compromising the ability of future generations to meet their own needs. It encompasses both renewable energy sources and energy efficiency measures, aiming to minimize environmental impact and promote social equity.
Sustainable growth – It means achieving economic expansion in a way which benefits both the present and future. It is about balancing economic progress with environmental responsibility and social well-being, ensuring resources are not depleted and future generations can also prosper.
Sustainable production – It is a way of creating goods and services which minimizes negative impacts on the environment, conserves natural resources, and promotes social and economic well-being, ensuring that present needs are met without compromising the ability of future generations to meet their own needs. This holistic approach considers the entire product lifecycle, from sourcing and design to production, distribution, and disposal, focusing on reducing waste, lowering emissions, and using renewable energy and ethical labour practices.
Sustainable supply chain (SSC) – It integrates ethical and environmentally responsible practices across the entire process of creating and delivering a product or service, extending from raw material sourcing to final disposal, with a goal to minimize negative social and environmental impacts while achieving organizational goals. It balances the ‘triple bottom line’ (planet, people, and profit) by considering the social, environmental, and economic impacts of the supply chain network.
Sustainable use – It is defined as the use of components of biological diversity in a way and at a rate which does not lead to the long-term decline of biological diversity, thereby maintaining its potential to meet the needs and aspirations of present and future generations. This assessment notes that sustainable use is also an outcome of social-ecological systems which aim to maintain biodiversity and ecosystem functions in the long term, while contributing to human well-being.
Swab pressure – It is a reduction in well-bore hydrostatic pressure which occurs when a drill string or casing is pulled out of the hole too quickly, creating a piston-like effect that removes fluid from the wellbore. This pressure decrease can lower wellbore pressure to a point where formation fluids can enter the well-bore, potentially causing a well control issue like a kick.
Swabbing – It is the wiping of the sample surface with a cotton ball saturated with etchant to remove reaction products simultaneously.
Swage – It is the operation of reducing or changing the cross-sectional area of stock by the fast impact of revolving dies. It is also the tapering of bar, rod, wire, or tubing by forging, hammering, or squeezing, reducing a section by progressively tapering lengthwise until the entire section attains the smaller dimension of the taper.
Swaging – It is tapering bar, rod, wire, or tubing by forging, hammering, or squeezing, reducing a section by progressively tapering lengthwise until the entire section attains the smaller dimension of the taper.
Swamp – It is a general term that is defined as spongy land, low ground filled with water, soft wet ground, hence its association with a wide variety of terrestrial ecosystems. It is a forested wetland. Swamps are considered to be transition zones since both land and water play a role in creating this environment. Swamps vary in size and are located all around the world. The water of a swamp can be fresh water, brackish water, or seawater.
Swarf – It consists of intimate mixture of grinding chips and fine particles of abrasive and bond resulting from a grinding operation.
Swash-plate – It is a mechanical device, normally an angled plate on a rotating shaft, which translates rotary motion into reciprocating (back-and-forth) motion, or vice versa. It is important in applications like pumps, and motors.
Sweat soldering – It consists of soldering process variation in which two or more parts that have been precoated with solder are reheated and assembled into a joint without the use of additional solder.
Sweating – It is exudation of bearing material or lubricant due to high temperature. It is the action by which all or a portion of the low melting constituent of a compact is forced to the surface during sintering. It is sometimes referred to as ‘bleed out’. It is also called exudation.
Sweep – It is a type of foundry pattern which is a template cut to the profile of the desired mould shape that, when revolved around a stake or spindle, produces that shape in the mould. It is used to remove excess material from a mould or core. It also means to form a mould or core by scraping the sand with a form sweep having the desired profile.
Sweeping gas membrane distillation (SGMD) – It is a membrane distillation process which uses a cold inert gas, like air, to actively sweep water vapour across a hydrophobic membrane and into an external condenser for collection as purified liquid. This method improves vapour flux and reduces mass transfer resistance by combining features of air gap and direct contact membrane distillation. By reducing heat and mass transfer resistance and utilizing low-grade heat sources, sweeping gas membrane distillation is a promising technology for desalination, removing volatile organic compounds (VOCs), and concentrating solutions.
Sweep velocity – It is the mean of the surface velocities of two bodies at the area of contact. Occasionally the sum of the velocities is quoted instead of the mean. In rolling, the sweep velocity is also called the rolling velocity.
Sweep work – It means forming of moulds or cores by the use of jigs or templates instead of patterns.
Swell – It is a casting defect consisting of an increase in metal section because of the displacement of sand by metal pressure. It can also refer to the increased volume of excavated earth or material because of the presence of air voids, or a temporary increase in root mean square (RMS) voltage in an electrical system. A swell factor, which is the ratio of loose to in-place volume, is used to calculate the additional space needed for excavated soil, while in electrical engineering, swells are momentary over voltages on power lines that can damage equipment.
Swelling – In coal, it is an increase in coal’s volume because of either in-situ thermal decomposition, where heating causes gas bubbles within the coal’s plastic state to expand its volume, or sorption by solvents or gases (like carbon di-oxide), which can penetrate and expand the cross-linked macro-molecular structure of the coal.
Swelling behaviour – It is the process where a solid material expands in volume after absorbing a fluid, such as water. This expansion is driven by the interaction and diffusion of fluid molecules into the material’s structure, which is influenced by the material’s properties and the fluid’s chemical potential. The equilibrium degree of swelling is reached when a balance forms between the forces which cause swelling (like solvent-polymer interactions) and the forces which esist it (like elastic retractive forces from the material’s network).
Swelling index of coal – It is also called, or free swelling index (FSI). It is a measure of how much coal expands in volume when heated without restriction, indicating its caking ability and suitability for coke manufacturing. A standard test, often performed as per standards, involves heating coal in a crucible and comparing the resulting ‘button’ shape to a visual scale from 0 to 9. Higher free swelling index values (typically 4-9) suggest good caking properties, while low values (0-2) indicate a non-caking or poorly caking coal, impacting its use in the production of metallugical coke.
Swift cup test – It is a simulative test for determining formability of sheet metal in which circular blanks of different diameters are clamped in a die ring and deep drawn into a cup by a flat-bottomed cylindrical punch. The ratio of the largest blank diameter which can be drawn successfully to the cup diameter is known as the limiting drawing ratio (LDR) or deformation limit.
Swing bridge – It is a type of movable bridge whose deck rotates horizontally around a vertical pivot point, allowing it to swing open and closed to permit the passage of tall ships or other vessels, or to enable multiple traffic routes across a canal or river. When closed, it functions as a standard road or railway bridge for traffic to cross.
Swing check valve – It is a check valve in which the closure element is a hinged clapper which swings or rotates about a supporting shaft. Swing check valves contain a disk which is hinged at the top. The disk seals against the seat, which is integral with the body. This type of check valve normally has replaceable seat rings. The seating surface is placed at a slight angle to permit easier opening at lower pressures, more positive sealing, and less shock when closing under higher pressures. Swing check valves are normally installed in conjunction with gate valves since they provide relatively free flow. They are desired for lines having low velocity flow and are not to be used on lines with pulsating flow when the continual flapping or pounding is destructive to the seating elements. This condition can be partially corrected by using an external lever and weight.
Swing forging – It is also known as swing-hammer forging or drop forging. It is a method of shaping metal by applying compressive forces to a billet or work-piece using a hammer which swings or is dropped onto it. This process frequently utilizes heated metal to make it more malleable and easier to shape. The hammer’s blows, either manually or mechanically, deform the metal into the desired form.
Swing forging machine – It is the equipment for continuously hot reducing ingots, blooms, or billets to square flats, rounds, or rectangles by the crank-driven oscillating action of paired dies.
Swing frame grinder -It is a grinding machine suspended by a chain at the centre point so that it can be turned and swung in any direction for grinding of billets, large castings, or other heavy work. Principal use is removing surface imperfections and roughness.
Swinging load – It is a load which changes at relatively short intervals.
Swirl burner – It is a combustion device which utilizes guiding vanes to create a swirling flow of secondary combustion air, improving the mixing of fuel and oxidant, improving heating efficiency, and reducing emissions compared to conventional burners.
Swirl flow meter – It is a type of flow meter which measures fluid velocity by detecting the frequency of a swirling flow pattern created by a guide on the flowmeter’s inlet. This swirling flow pattern is similar to the vortices created in a vortex flowmeter, but swirl flowmeters do not need the same long, straight pipe runs as vortex flowmeters. The frequency of the swirl is directly proportional to the fluid’s flow rate, allowing for accurate measurement.
Swirling flow – It is a fluid motion characterized by a rotational component, which generates different flow structures and is utilized in applications such as flame stabilization in combustion systems by improving the mixing of fuel and air.
Swirl-nozzle technique – It is a new technique at sub-entry nozzle (SEN) which has reported to improve the fluid flow pattern and inclusion removal. A fixed blade placed at the upstream end of the sub-entry nozzle induces a swirl flow in nozzle. Centrifugal force generated by the swirling flow in the nozzle can distribute the liquid steel equally to its two spouts. Since liquid steel stream with centrifugal force has the maximum velocity in the vicinity of the wall inside the nozzle, it tends to flow out of the upper part of the spout. Hence, the velocity distribution which tends to have higher values toward the lower part of the spout with a conventional nozzle can become uniform. It has been reported that by using this swirl nozzle for the continuous casting, the defect ratio of finish products (coils) has decreased to 25 % of the conventional nozzles, and casting speed has risen by 30 %. Its cost is higher only by 20 % than the cost of the conventional and hence it is cheaper than using an ‘electro-magnetic brake’. This swirl flow pattern can also be generated by the ‘electro-magnetic stirring’ at the nozzle, which can also improve the solidification structure of the cast steel as well.
Switch – It is an electrical component which opens and closes a circuit. can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. A switch can be manually operated, automatically operated by some other electrical circuit, or operated by the change in some physical condition such as flow, level, or temperature. In case of conveyor systems, switch is a contrivance facilitating the connection of two or more adjacent package conveyor lines. It is frequently an electrical control device governing the flow of materials.
Switched reluctance motor – It is a motor that relies on induced magnetism in salient poles, instead of a rotor winding.
Switched-mode power supply – It is a power converter which regulates voltage by adjusting the time duration of a switching device. This gives reduced heat dissipation compared to an equivalent linear regulator device.
Switch-gear – It is an array of switches, circuit breakers and related apparatus for power distribution.
Switching control – It is a control strategy which switches between different control laws or strategies to manage complex systems, frequently those with multiple operating modes or uncertainties. The core principle is to change the control signal or method based on the system’s current state or performance requirements to maintain stability and achieve optimal performance, as seen in sliding mode control, power electronics converters, and network systems.
Switching frequency – It is the rate at which an electronic component, like a transistor or sensor, turns on and off per second, measured in Hertz (Hz). In power electronics, it is the speed at which a power semi-conductor is switched for processes like pulse width modulation (PWM), directly impacting power losses and circuit efficiency. Higher frequencies normally lead to more power loss but allow for smaller, lighter components, creating a trade-off in design.
Switching sequence – It is the specified order in which electrical or electronic switches are opened and closed to achieve a desired outcome, such as transforming a network into a spanning tree or controlling the operation of devices like power converters. It defines the precise timing and arrangement of switching operations to ensure a system transitions from an initial state to a final, restored state.
Switch-over time – It refers to the period taken to transition from one state, operation, or product to another, which can vary considerably depending on the context, from a few minutes for a manufacturing changeover to a period for shifting systems or duties in engineering or technology. It basically means the duration of the switch-over or change-over process itself.
Switch-room – It is a specially designed room that houses electrical switching and distribution equipment, such as switch-boards, circuit breakers, and control panels, to manage and distribute electricity within a facility. These rooms frequently need restricted access to authorized personnel, have environmental controls for temperature and humidity, and are crucial for maintaining the safe and efficient operation of a facility’s electrical systems.
Swivel ring flange – In the swivel ring flange, a hub is butt welded to the pipe as in the case of the lap joint flange. A swivel ring sits over the hub and allows the joint to be bolted together. Swivel ring flanges are normally found on sub-sea services where the swivel ring facilitates flange alignment. The flange is sealed using a ring type joint (RTJ) metal gasket.
SWOT analysis – SWOT is the acronym for Strengths (S), Weaknesses (W), Opportunities (O), and Threats (T). By definition, strengths and weaknesses are considered to be internal factors over which there are some measures of control. On the other hand, by definition, opportunities and threats are considered to be external factors over which there are essentially no controls. SWOT analysis is a simple but powerful tool for sizing up the organizational resource capabilities and deficiencies, its market opportunities, and the external threats to its future. It is also referred to as SWOT matrix and can also be formulated as TOWS analysis or Weihrich’s TOWS matrix. SWOT is a strategy analysis tool. It combines the study of the strengths and weaknesses of an organization, a geographical area, a sector, an industry, a product or a project with the study of the opportunities and threats to their environment.
Syenite – It is an intrusive igneous rock composed chiefly of orthoclase.
Sylvite – It is potassium chloride, which is the principal ore of potassium mined for fertilizer manufacturing.
Symbolic circuit analysis – It is analytical circuit analysis in terms of expressions with variables, instead of numerical solutions for a particular case of values.
Symmetric – It is said of distributions which shows no skewness, and for which exactly 50 % of cases lie above and below the mean of the distribution.
Symmetrical – A list of numbers is symmetrical if the data values are distributed in the same way, above and below the middle. Symmetrical data sets are (i) easily interpreted, (ii) allow the presence of outliers to be detected similarly (i.e., using the same criteria), whether they are above the middle or below and (iii) allow the spread (variability) of similar data sets to be compared. Some statistical techniques are appropriate only for data sets which are roughly symmetrical, (e.g., calculating and using the standard deviation). Hence, skew data are sometimes transformed, so they become roughly symmetric.
Symmetrical components – It is a technique to simplify analysis of unbalanced polyphase systems.
Symmetrical edge wave – It is a flatness defect in which the edges on both sides of the steel piece are ‘wavy’ because of the steel material at the edges are longer than the material in the centre.
Symmetrical laminate – It is a composite laminate in which the sequence of plies below the laminate midplane is a mirror image of the stacking sequence above the midplane.
Symmetric flow – It refers to flow properties which are uniform across parallel geometric planes in planar flows or around a common axis in axial flows, allowing for a reduction in the number of independent geometry variables needed for design and analysis.
Symmetric membranes – These are synthetic membranes which have uniform structures throughout their cross section, maintaining consistent flux regardless of variations in thickness, typically ranging between 100 micro-meters and 300 micro-meters. These membranes are normally used in processes such as micro-filtration.
Symmetric operation – It is defined as a transformation applied to a physical system which does not alter any of its physical properties, allowing for the analysis of the system’s parameters while maintaining their invariance under the operation.
Symmetric structure – It is an assembly in which individual sub-units are arranged in a manner which needs the fewest number of distinct interfacial contacts, facilitating easier evolution and design, as shown in naturally occurring macro-molecular assemblies.
Symptom based emergency response guidelines (SBERGs) – These guidelines provide advisory guidance to nuclear operators following a beyond design basis accident in an advanced gas cooled reactor.
Synchro – It is a synchro-motor, a class of electrical motors which follows the rotation of a source.
Synchronization – It is the aligning the timing of two or more sources, such as synchronizing a generator before connecting it to a grid.
Synchronous circuit – It is a logic circuit where internal state changes only propagate in step with a master clock signal.
Synchronous generator – It is a generator which operates at synchronous speed, determined by the frequency of the connected grid, and does not need reactive magnetizing current. It can utilize either permanent magnets or conventional field windings to create its magnetic field and is normally used in applications such as wind turbines.
Synchronous motor – It is an alternating current motor which operates at a constant speed, known as synchronous speed, which is directly proportional to the frequency of the supply current and inversely proportional to the number of poles of the motor. The rotor of a synchronous motor rotates at the same speed as the rotating magnetic field produced by the stator.
Synchronous rectification – It is a converter from alternating current to direct current, where switching devices actively are operated in step with the positive and negative excursions of the supply.
Synchronous speed – It is the speed at which a rotating magnetic field (RMF) in an alternating current electrical machine, like a synchronous motor or generator, rotates. It is a constant speed determined by the frequency (f) of the power supply and the number of poles (P) in the machine, calculated using the formula Ns = 120 f/P, where ‘Ns’ is the synchronous speed in revolutions per minute (rpm).
Synchronous system – It is one which operates based on a common, shared timing reference, such as a global clock signal, ensuring that events occur in a coordinated and predictable manner over time. This shared timing allows processes to run in step, information to be transferred between components at regular intervals, and all parts of the system to be ‘locked’ to the same time base. Key characteristics include defined time bounds for events, the use of clock signals for data transfer, and mechanisms like setup and hold times to ensure reliability.
Synchronous timing (resistance welding) – It is the initiation of each half cycle of welding transformer primary current on an accurately timed delay with respect to the polarity reversal of the power supply.
Synchroscope – It is an instrument which is used to bring an alternating current generator into synchronization with a grid, which uses a moving pointer or set of lamps.
Synchrotron – It is a device for accelerating charged particles by directing them along a roughly circular path in a magnetic guide field. As the particles pass through accelerating cavities placed along their orbit, their kinetic energy is increased repetitively, multiplying their initial energy by factors of hundreds or thousands.
Synchrotron radiation -It is an electromagnetic radiation which is emitted by charged particles in circular motion at relativistic energies.
Syncline – It is a down-arching fold in bedded rocks.
Syneresis (of a grease) – It is the separation of oil (or other fluid) from a grease.
Synergy – It is the interaction or cooperation of two or more organizations, substances, or other agents to produce a combined effect higher than the sum of their separate effects.
Synectics – It is a creative problem-solving process in which the problem statement or product design specification is transformed through the use of analogies.
Syngas – It is also called synthesis gas. It is a fuel gas mixture mainly composed of carbon mono-oxide (CO) and hydrogen (H2), frequently with carbon di-oxide (CO2) and nitrogen (N2) as well. It is produced from carbon-containing feedstocks like natural gas, bio-mass, or coal through a gasification process. Syngas serves as an important intermediate for creating chemicals such as methanol and hydrocarbons through the Fischer-Tropsch synthesis.
Syngenetic – It is a term which is used to describe when mineralization in a deposit has been formed relative to the host rocks in which it is found. In this case, the mineralization has been formed at the same time as the host rocks. It is the opposite of epigenetic.
Syntactic foams – These are composites made by mixing hollow microspheres of glass, epoxy, phenolic, and so on, into fluid resins (with additives and curing agents) to form a mouldable, curable, lightweight, fluid mass, as opposed to foamed plastic, in which the cells are formed by gas bubbles released in the liquid plastic by either chemical or mechanical action.
Syntectic equilibrium – It is a reversible univariant transformation in which a solid phase which is stable only at lower temperature decomposes into two conjugate liquid phases which remain stable at higher temperature.
Syntectic system – It is the three-phase equilibrium. It consists of two liquid phases and one solid phase, which is similar in this sense to the monotectic equilibrium.
Synthesis Energy Systems (SES) gasification technology – Synthesis Energy Systems has a worldwide exclusive license for the U-Gas gasification technology, which is a single stage fluidized bed system and which can provide a low-to-medium heating value syngas. Synthesis Energy Systems gasification technology is particularly suitable for gasifying low quality fuels, including all ranks of coal. Dried and ground coal is fed via a lock-hopper into the gasifier, which is fluidized by a mixture of steam and oxygen. These reactant gases are introduced at the bottom of the gasifier through a distribution grid, and at the ash discharge port in the centre of the distribution grid. The bed is maintained at temperatures ranging from 840 deg C to 1,100 deg C depending on the softening temperature of the ash within the fuel. At such conditions, the concentration of fuel ash (mineral content) particles within the gasifier increases such that they begin to agglomerate and form larger particles, which are selectively removed from the fluidized bed by gravity. This design allows for 95 % or more of the fuel’s carbon getting gasified.
Synthetic chemicals – These are substances created by humans through chemical processes or bio-synthesis, as opposed to those made by nature. These man-made compounds can be either entirely new, or they can be chemically identical to naturally occurring substances but produced artificially. These man-made compounds are frequently not easily degradable or bio-degradable and can contain hazardous substances, posing potential health risks to humans and the environment.
Synthetic cold-rolled sheet – It is a hot-rolled pickled sheet given a sufficient final temper pass to impart a surface approximating that of cold-rolled steel.
Synthetic esters – These are chemical compounds created through esterification, a reaction between an alcohol and a carboxylic acid. They are known for their versatile properties, including bio-degradability and high moisture tolerance, making them suitable for several applications like lubricants and insulating liquids in transformers
Synthetic fibres – These fibres are man-made fibres which are produced through chemical processes, as opposed to natural fibres which are derived directly from living organisms. These fibres are typically created from polymers, which are long chains of molecules formed by chemically joining smaller units called monomers.
Synthetic fluids – These are man-made liquids produced through chemical synthesis, rather than derived from natural sources like petroleum. They are designed to have specific, predictable properties and are often used in applications where superior performance, durability, or resistance to extreme conditions is required. Synthetic fluids are selected since a mineral oil is deficient in some respect for a particular application. They are used where mineral oils are inadequate due to (i) oxidation and viscosity loss at high temperature, (ii) combustion or explosion, and (iii) solidification at low temperature. They are engineered specifically in uniformly shaped molecules with shorter carbon chains which are much more resistant to heat and stress. Synthetic fluids are expensive, but normally are more available in good quality than even the more stable of the mineral oils.
Synthetic fuel – They are also known as synfuel. It is a man-made fuel created through chemical processes, typically by reacting hydrogen with carbon sources like carbon di-oxide or bio-mass, and powered by renewable energy sources. These fuels are engineered to mimic the properties of traditional fossil fuels such as gasoline, diesel, and natural gas, making them compatible with existing infra-structure.
Synthetic gas – It is also called syngas. It is a fuel gas mixture primarily composed of carbon mono-oxide (CO) and hydrogen (H2). It is an artificially produced mixture that can be made from different carbon-containing feedstocks, such as bio-mass, coal, natural gas, or waste. Syngas is a crucial intermediate in the chemical industry, used in the Fischer-Tropsch synthesis to produce liquid fuels like gasoline, diesel, and jet fuel, as well as other chemicals and products like methanol.
Synthetic hydrocarbon – It is a hydrocarbon, an organic compound composed of only carbon and hydrogen atoms, which is produced artificially rather than naturally. This includes synthetic fuels and oils, which can be made from several raw materials through chemical processes like the Fischer-Tropsch process or by combining hydrogen and carbon di-oxide.
Synthetic hydrocarbon fluids (SHF) – These are man-made lubricants created through chemical synthesis, offering controlled molecular structure and predictable properties. Unlike mineral oils, they are not derived from petroleum but are instead manufactured from well-defined chemical compounds, frequently starting with petroleum-based materials. Synthetic hydrocarbon fluids, like polyalphaolefins (PAOs), are known for their excellent low-temperature performance, stability, and broader temperature range compared to conventional oils.
Synthetic lubricants – These are man-made lubricants which are not derived from petroleum but are produced through chemical synthesis. They offer improved performance and stability compared to conventional lubricants, especially in extreme temperature conditions. The process of creating synthetic lubricants involves carefully controlling the chemical composition to achieve specific desired properties.
Synthetic moulding sand – It is the sand compounded from selected individual materials which, when mixed together, produce a mixture of the proper physical and mechanical properties from which to make foundry moulds.
Synthetic oils – These are artificially developed substitutes for mineral oils. They are specifically developed to provide lubricating oils with superior properties than the mineral oils. Synthetic lubricating oils have viscosity which does not vary as much with temperature as in mineral oil. Their rate of oxidation is much slower but they are having high cost. The temperature resistant synthetic oils are used in high performance machinery operating at high temperatures. Synthetic oils for very low temperature applications are also available.
Synthetic organic chemical (SOC) – It is man-made (anthropogenic) organic chemicals. Some synthetic organic chemicals are volatile. Others tend to stay dissolved in water instead of evaporating.
Synthetic organic compounds – Synthetic organic compounds pollute water when they enter the water through various manmade activities such as production of these compounds, spillage during transportation, and their uses in different applications. These include synthetic pesticides, synthetic detergents, food additives, pharmaceuticals, insecticides, paints, synthetic fibers, plastics, solvents and volatile organic compounds (VOCs). Most of these compounds are toxic and bio-refractory organics i.e., they are resistant to microbial degradation. Even concentration of some of these in traces can make water unfit for different uses. The detergents can form foams and volatile substances can cause explosion in sewers. Polychlorinated biphenyls (PCBs) are used in the industries since 1930s which are complex mixtures of chloro-biphenyls. Being a fat soluble they move readily through the environment and within the tissues or cells. Once these compounds enter water, these compounds are exceedingly persistent and their stability to chemical reagents is also high.
Synthetic resin – It is a complex, substantially amorphous, organic semisolid or solid material (usually a mixture) built up by chemical reaction of comparatively simple compounds, approximating the natural resins in luster, fracture, comparative brittleness, insolubility in water, fusibility or plasticity, and some degree of rubberlike extensibility, but commonly deviating widely from natural resins in chemical constitution and behaviour with reagents.
Synthetic sands – These sands are synthetic mixture of silica sand and exact proportions of binders and additives instead of using natural sands.
Synthetic slag – It consists of prepared mixture of several individual oxides which is used during secondary steelmaking to assist the steel treatment in the ladle from the viewpoint of effective refinement. Synthetic slag practice is normally used to get clean steels and also for the desulphurization of the liquid steel.
Synthetic substance – It is also called synthetic compound. It refers to a substance which is man-made by synthesis, rather than being produced by nature. It also refers to a substance or compound formed under human control by any chemical reaction, either by chemical synthesis (chemo-synthesis) or by bio-synthesis.
Synthetic zeolite – It is an artificially created crystalline alumino-silicate material, engineered in a laboratory with specific, controllable pore sizes and structures. Unlike natural zeolites, which vary in purity and size, synthetic zeolites offer uniformity, high purity, and customized properties for industrial use as molecular sieves, adsorbents, and catalysts in several applications.
Syphon – Syphon is a protective device used to prevent steam from entering the internal works of a steam gauge. Frequently a syphon only consists of a single coil of high-pressure pipe with threaded ends.
System – It is a group of interacting or interrelated elements which act as per a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its boundaries, structure and purpose and is expressed in its functioning. Systems have several common properties and characteristics, including structure, function(s), behaviour and interconnectivity.
System architecture – It is the total plan for the design or product which lays out the type of sub-systems and ensures that they are properly related. A complex system contains the following levels namely total system, module, sub-system, sub-assembly, piece part, and piece-part feature.
Systematic analysis – It refers to a structured and methodical approach to examining or studying something, with the goal of understanding its components or drawing conclusions. It involves a defined process, ensuring all relevant aspects are considered and minimizing bias. This approach is used across several fields including organizational strategy, to improve decision-making and improve understanding.
Systematic error – It is an error, which is in some sense biased, having a distribution with a mean that is not zero (as opposed to a random error). Systematic error is a constant uniform deviation of the operation of an instrument is known as systematic error. It is because of the problems with instruments, environment effects, or observational errors. There are two types of systematic errors namely (i) static error, (ii) dynamic error.
System block diagram – It is a simplified, high-level visual representation of a system, process, or project using rectangular blocks for components and lines with arrows to show the flow of information or signals between them. It provides a functional overview of how different parts of a system interact, illustrating inputs, outputs, and relationships without showing excessive detail, making complex systems easier to understand, analyze, and design.
System (crystal) – It is one of seven groups into which all crystals can be divided namely triclinic, monoclinic, orthorhombic, hexagonal, rhombohedral, tetragonal, and cubic.
System design – It is the process of defining the architecture, components, modules, interfaces, and data for a system to meet specific requirements. It involves creating a blueprint which outlines how different parts of a system are going to work together to achieve a desired functionality, ensuring a coherent and efficient system. This includes defining the system’s structure, behaviour, and the interactions between its different elements. System design is the primary product-development stage in which the basic architecture of the product or process is determined. It is the first stage of robust design, as defined by Genichi Taguchi.
System failure probability – It is the likelihood that a system is going to stop functioning as intended within a specific timeframe or under certain conditions. It is a key metric in reliability engineering, used to assess safety and performance, and is calculated by considering the number of failures against the total operating time or demand. Understanding this probability helps engineers and decision-makers design more reliable systems, implement effective maintenance, and manage risks.
Systeme International d’Unites – It is internationally recognized system of measurement and the modern form of the metric system. Prefixes and units are created and unit definitions are modified through international agreement as the technology of measurement progresses, and as the precision of measurements improves. It is abbreviated to SI.
System identification – It is the process of creating a mathematical model of a system from collected input and output data. This involves selecting a model structure, estimating parameters within that structure to best fit the observed data, and then validating the model’s adequacy. The resulting model can then be used for simulation, controller design, or analysis in a wide range of fields.
Systematization – It is the act of arranging or organizing something according to a system or a rationale to make it orderly, coherent, and more effective. It involves breaking down a task into orderly steps, sorting concepts into logical order, or formalizing processes to ensure they run smoothly and efficiently.
System noise – It refers to unwanted, random fluctuations in an electronic system which can interfere with the desired signal. It essentially represents the sum of all noise sources present within a system, including those generated by its components and external interference. This noise can degrade signal quality and affect the accuracy of measurements or data transmission. In statistics, system noise which is also called statistical noise, refers to the unexplained variability or randomness within a data sample. This noise can be thought of as the error term in a statistical model, representing the deviation of individual observations from the expected value. It is a random process which can interfere with the analysis of meaningful data.
System on a chip – It is an integrated circuit which combines multiple significant subsystems of a product on one die, for example, analog signal processing and digital controls.
System on module – It is a packaging of significant functions of a complete product in a form which can be used in more than one product.
Systems – These refer to complex industrial processes which involve the control, optimization, and modeling of metallurgical furnaces and reactors, with the objectives of maximizing product quality, minimizing energy consumption, and reducing environmental impact while addressing the challenges posed by heterogeneous conditions and poorly defined parameters.
System safety assessment (SSA) – It is a risk management process which uses a systematic methodology to verify that a system’s design meets safety requirements and achieves acceptable risk levels by analyzing hazards, their causes, and their potential consequences throughout the system’s life cycle. The assessment identifies potential risks, develops mitigation strategies, and ensures ongoing compliance with established safety objectives and standards.
System safety engineering – It is a discipline which uses engineering and management principles to identify, evaluate, and control hazards and risks within a system throughout its entire life cycle, aiming to prevent accidents and mishaps which can result in injury, death, property damage, or environmental harm. It involves analyzing potential risks, their causes, and their potential severity to reduce or eliminate them, ensuring a system can operate safely and effectively.
System sand – It is the foundry sand used in making moulds and which eventually becomes the bulk of the sand used in the mechanical system or mechanized unit.
Systems approach to management – System approach to management concentrates on the organization as a whole which includes (i) the internal and external components, (ii) people working in the organization, (iii) work processes of the organization, and (iv) overall environment under which the organization is functioning. It makes use of computer technology and provides the manager a framework within which internal and external factors influencing the decision making can be visualized. System approach to the management emphasizes total environment under which the organization is functioning. In system approach to management, the management cycle consists of input, transformation to output, and renewed input. During the management cycle, environment changes are assessed continually in a structured manner for the determination of their impact. System approach to management considers organization as a total system where a change in any one aspect of the environment has an effect on the other components of the organization. In this approach, the specifics are analyzed considering the complete organizational environment. The whole organization is considered as one entity which functions in a specific environment where essential parts are interdependent.
Systems design stage – It is the initial stage. In it, systems design (the available science, technology, and experience bases) is used to develop and select the basic design alternative to meet customer needs. A variety of techniques can be useful in specifically mapping the relationship between customer needs and the selection of design configuration and parameters which effectively meets those needs. The methods of quality function deployment can be most useful at this stage of the design process.
Systems engineering – It is an interdisciplinary field focused on creating, managing, and integrating complex systems to meet specific needs throughout their entire lifecycle. It involves a holistic approach, viewing the system as a whole rather than isolated parts, to ensure all components work together effectively. Systems engineers manage the entire process, from defining customer needs and designing the system to its implementation, verification, and ongoing support, resolving conflicts between different engineering disciplines and stakeholders along the way. Systems engineering focuses on defining a system’s requirements, architecture, and overall structure in the early stages of a project. It involves identifying the system’s purpose, stakeholders’ needs, and the functional and physical characteristics needed to meet those needs.
System structure – It is the arrangement and organization of technical elements within a system, including their functional relationships, operational parameters, and constraints which influence system performance and reliability.
System verification test – It is a final verification of robustness of the system which is normally performed on the first total-system prototypes, which are made after the detail design has been completed.
System voltage – It refers to the overall voltage level of an electrical system, typically the nominal or rated voltage that the system operates at. In the context of renewable energy systems, it often designates the battery bank’s voltage. Common system voltages include 12 volts, 24 volts, and 48 volts.
S-Z lay – In a steel cord conveyor belt, Z and S lay steel cords are used alternately to ensure a straight running behaviour of the belt.
Leave a Comment