Glossary of technical terms for the use of metallurgical engineers Terms starting with alphabet ‘P’
Glossary of technical terms for the use of metallurgical engineers
Terms starting with alphabet ‘P’
P2 etch – It uses ferric sulphate (FeSO4) in place of the toxic sodium dichromate as the oxidizer (15 % ferric sulphate, 37 % sulphuric acid (H2SO4). and 48 % water and produces an oxide with a similar morphology to those got using the different chromic-sulphuric etches. The P2 etch produces similar initial bond strengths and durability to that of FPL (forest products laboratory) etch.
Package – It is a bundle of things packed and wrapped. In case of composites, package consists of yarn, roving, and so on in the form of units capable of being unwound and suitable for handling, storing, shipping, and use.
Packaged boiler – It is a boiler supplied with all of its components i.e., burner, controls and auxiliary equipment, designed as a single engineered package, and ready for on-site installation.
Package flow conveyor – It is a conveyor system installed within racking, featuring either a wheel bed or roller configuration.
Package stop – It consists of different devices, whether manual or mechanical which are utilized to halt the movement on a conveyor.
Packaging – It can be described as a coordinated system of preparing goods for transport, warehousing, logistics, sale, and end use. Packaging contains, protects, preserves, transports, informs, and sells.
Packaging and bundling machines – These machines provide steel mills with efficient methods of packaging to protect their products when they are being shipped. Using packaging machines improves packaging speed, efficiency, and ensures proper calibration.
Packaging films – These refer to materials used for enclosing or protecting products. These films include industrial liners and bubble packing. These films are designed to improve product preservation and facilitate storage and transportation.
Packaging machines – These refer to different types of machinery used in the packaging process, including but not limited to blister, vacuum, capping, cartoning, filling, and sealing machines, designed to improve efficiency, productivity, and quality in packaging operations.
Packaging materials – Thee refer to substances used to enclose and protect products during storage and transportation, ensuring their preservation and providing essential product information. These materials can include several options, with a growing emphasis on environmentally friendly and bio-degradable alternatives to traditional plastics.
Packaging, nuclear fuel – It is a special way of processing spent fuel for temporary storage or final disposal.
Packaging radioactive waste – It is an operation whereby waste is converted into a form suitable for transportation and/or storage and/or final disposal. Very low-level radioactive waste (vinyl, cleaning rags, etc.) is placed in steel drums. Low-level wasted and intermediate-level waste is first compacted to reduce its volume as far as possible, then encapsulated in a special material (concrete, bitumen or resin matrix) to form solid blocks capable of withstanding all environmental conditions. High-level waste is placed in a glass mixture (vitrification process). Once vitrified, the waste is placed in stainless steel canisters.
Pack carburizing – It is a method of surface hardening of steel in which parts are packed in a steel box with a carburizing compound and heated to high temperatures. In this process low carbon steel components are packed in an environment with high carbon content such as cast-iron shavings or carbon powder. The components are heated with the production of carbon monoxide, which is a reducing agent. The reduction occurs on the steel surface with the release of carbon that is diffused into the surface because of high temperatures. With the carbon absorption inside the component, the steel components are hardened. The surface carbon is in the range of 0.7 % to 1.3 % depending on the process environment. The case depth is around 0.1 millimeter to 1.5 millimeter. Control of pack carburizing is difficult since it is difficult to maintain uniform temperatures. Pack carburizing is effective in introducing carbon but this method is exceedingly slow. Common carburizing compounds contain 10 % to 20 % alkali or alkaline earth metal carbonates (for example, barium carbonate, BaCO3) bound to hardwood charcoal or to coke by oil, tar, or molasses. This process has been largely supplanted by gas and liquid carburizing processes.
Pack cementation – It is a coating process akin to pack carburizing which involves packing the parts to be coated into a retort with a carefully blended mixture of powders and then exposing the pack under hermetically sealed conditions or an inert atmosphere to elevated temperatures. Pack cementation is principally used for the application of aluminum diffusion coatings and ceramic coatings.
Packed-bed scrubbers –They consist of a chamber containing layers of variously-shaped packing material, such as Raschig rings, spiral rings, or Berl saddles, that provide a large surface area for liquid-particle contact.
Packed density – It is the density of a powder when the volume receptacle is tapped or vibrated under specified conditions while being loaded.
Packed tower – It is a type of chemical processing column filled with packing material instead of trays, used to facilitate mass transfer between gas and liquid phases. Liquid is typically sprayed from the top and flows downward, while gas flows counter-currently from the bottom, creating a high-surface-area environment, where absorption, distillation, or other separation processes can occur efficiently.
Pack hardening – It is also known as case hardening. It is a heat treatment process which increases the hardness of a metal’s surface layer while leaving the core relatively soft and tough. This is achieved by introducing a high concentration of carbon into the surface of the metal, normally through diffusion at high temperatures. The process involves packing the metal part in a carbon-rich material like charcoal inside a sealed container and heating it.
Packing – It is the process of placing items into the packaging container. In case of a valve, packing is the deformable sealing material inserted into a valve stem stuffing box, which, when compressed by a gland, provides a tight seal about the stem.
Packing box (assembly) – It is the part of the bonnet assembly used to seal against leakage around the closure member stem. Included in the complete packing box assembly are various combinations of some or all of the component parts such as packing, packing follower, packing nut, lantern ring, packing spring, packing flange, packing flange studs or bolts, packing flange nuts, packing ring, packing wiper ring, felt wiper ring, Belleville springs, and anti-extrusion ring.
Packing density – It is the ratio of the volume occupied by particles or fibres to the total volume of a bulk material, indicating how compactly they are arranged. A higher packing density means fewer voids and a more efficient use of space, which can reduce the need for expensive binders or increase the efficiency of a system by maximizing the quantity of functional material in a given volume. Factors like particle shape, texture, and size distribution significantly influence packing density. In case of powders, it is the weight of a unit volume of powder, normally expressed as grams per cubic meter, determined by a specified method.
Packing device – It is also known as a packaging machine. It is a piece of equipment which automates the process of placing products into protective containers, preparing them for sale, transport, or storage by filling, sealing, labeling, and boxing them. These devices vary in complexity from simple sealing mechanisms to fully integrated, high-speed automated systems which use robotics and artificial intelligence (AI) for handling different tasks.
Packing material – It is a material in which compacts are embedded during the pre-sintering or sintering operations. The material can act as a getter to protect the compacts from contamination.
Pack nitriding – It is a method of surface hardening of steel in which parts are packed in a steel box with a nitriding compound and heated to high temperatures.
Pack rolling – It is the hot rolling a pack of two or more sheets of metal. Scale prevents their being welded together.
Pad – It is the general term which is used for that part of a die which delivers holding pressure to the metal being worked. In casting, it is the metal added deliberately to the cross section of a casting wall, normally extending from a riser, to ensure adequate feeding to a localized area in which a shrink can occur without the addition.
Padding – It is the process of adding metal to the cross section of a casting wall, normally extending from a riser, to ensure adequate feed metal to a localized area during solidification where a shrink occurs if the added metal is not present.
Paddle mixture – It is a mixer which uses paddles mounted on a rotating shaft or disk to move and mix the powder.
Pad lubrication – It is a system of lubrication in which the lubricant is delivered to a bearing surface by a pad of felt or similar material.
Padmount transformer – It is a kind of metal enclosed distribution transformer which is suitable for mounting on grade.
Paint – It is a material or mixture which, when applied as a liquid to a surface forms a solid film for the purpose of decoration and / or protection. As art, this is used to create an image or images known as a painting. Normally, a paint contains a binder(s), solvent(s), and a pigment(s). Frequently other materials are present to give special properties to the paint film. Examples of such additives are rust inhibitors, light stabilizers, and softening agents (plasticizers). Paint can be made in several colours and types. Majority of the paints are either oil-based or water-based, and each has distinct characteristics.
Painting – It is defined as the process of applying paint, or another medium, to a solid surface. Paints or other forms of colour are normally applied to using a paintbrush.
Paint strippers – These are chemical formulations used to remove paint, frequently containing strong solvents like methylene chloride, which can act quickly but pose safety risks to eyes and skin. To improve effectiveness and slow evaporation, they can contain wax and need precautions such as protective gear and covering to maintain their liquid state.
Paired electron – It is one of two electrons which together form a valence bond between two atoms.
Paired t test – It is a test for the difference between means for two groups when the groups are not independently sampled.
Pairwise comparisons – These refer to a technique where experts assess the relative importance of criteria within a hierarchical structure by comparing two criteria at a time, which simplifies the decision-making process and allows for consistency checks.
Palladium – It is a chemical element, with symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal. Palladium, platinum, rhodium, ruthenium, iridium and osmium form a group of elements referred to as the platinum group metals (PGMs). They have similar chemical properties, but palladium has the lowest melting point and is the least dense of them.
Palladium barrier leak detector – It is a leak detector using hydrogen as the tracer gas and using the principle of hydrogen diffusing rapidly through a hot palladium barrier into an evacuated vacuum gauge.
Palladium-based membrane – It is a metallic membrane composed mainly of palladium (Pd) and its alloys, designed to selectively separate hydrogen from gas mixtures through a dissolution-diffusion process. These membranes are characterized by their high hydrogen permeability and selectivity, allowing for the production of ultra-pure hydrogen. However, they are expensive and can be susceptible to poisoning by contaminants like sulphur, needing careful process design and manufacturing to maintain performance in different industrial applications.
Palladium coating – It is a thin, protective, or functional layer of the silvery-white precious metal palladium (Pd) applied to the surface of a substrate, frequently a different metal or ceramic. This coating is created using methods such as electroless plating or electroplating, resulting in a chemically bonded surface which improves the substrate’s properties, such as its corrosion resistance, electrical conductivity, or catalytic activity, depending on the application and the specific characteristics of the palladium layer.
Palladium nitrate – It is chemically known as palladium(II) nitrate with the formula Pd(NO3)2. It is an inorganic compound which appears as a yellow to green crystalline solid. It is used as a source for preparing palladium-based catalysts, particularly in organic synthesis, and as a chemical modifier in electrothermal atomization atomic absorption spectroscopy (ETA-AAS). It is also a precursor for palladium films and nano-particles and can be a source for palladium in other chemical applications.
Pallet boxes – These are large industrial boxes fixed to or on top of pallets, which can be used to transport products in bulk.
Pallet flow conveyor – It is a conveyor specifically designed for the smooth movement of pallets, containers, and heavy loads, typically within a rack structure.
Pallet lifters – They use forks to lift pallets from underneath.
Pallets – It consists of a flat transport structure which supports goods stably, frequently in the form of wood. It allows for easy lifting and movement by forklifts.
Palm oil methyl ester (POME) – It is a methyl ester produced through the trans-esterification of crude palm oil with alcohol, resulting in a fuel additive which has lower viscosity and reduced emissions compared to conventional diesel. It is used in fuel blends to improve combustion efficiency and reduce nitrogen, sulphur, and carbon oxide emissions.
Pan – It is used to wash gravel, sand or crushed rock samples in order to isolate gold or other valuable metals by their higher density. The typical pan is a light but rugged circular metal dish with a flat bottom and sides which slope out at about 45-degree. Its inner surface is required to be smooth and free from grease and rust.
Pan-cake forging – It is a rough forged shape, normally flat, which can be got quickly with minimal tooling. Considerable machining is normally needed to achieve the finish size.
Pan-cake grain structure – It is a metallic structure in which the lengths and widths of individual grains are large compared to their thicknesses.
Panchromatic (PAN) image – It is a single-band, grayscale image with high spatial resolution which captures a broad range of the electro-magnetic spectrum, frequently the entire visible light range. Unlike multi-spectral (MS) images, which have multiple narrow bands and show colour, a Panchromatic image has only one band and hence lacks colour information but provides much finer spatial detail, like a detailed black-and-white photograph.
Panel – It is normally a flat, frequently prefabricated, component of a larger structure or system, serving purposes like support, enclosure, insulation, or control, and made from different materials. The term can also refer to an entire panelized assembly, such as an electrical control panel containing breakers and monitoring equipment, or a specific mathematical / numerical method called the panel method used in fluid dynamics.
Panel buildings – These refer to buildings which are (i) built of structural insulated panels, and (ii) built of pre-fabricated concrete blocks. Panel buildings can be either frameless (column-less), or the panels can be fitted to (i) timber-framed, steel-framed, or reinforced concrete-framed buildings, (ii) over common blockwork, or (iii) over existing masonry products.
Panel spalling test – It is a test using a panel of the refractory being tested to provide a reference to spalling behaviour.
Panning – It is one of the principal techniques of the individual prospector for recovering gold and diamonds in placer (alluvial) deposits.
Panoramic analyzer – It is an instrument for analyzing sounds and displaying the results either on an oscilloscope or a graph.
Pan or apron conveyor – This is the most common type of chain conveyor. It consists of one or more strands of endless chain, normally link plate roller type, running in steel guides. Rollers ensure minimum pulling effort in the chain, while roller guides supported on the super-structure of the conveyor, carry the entire load of the materials and chains. The carrying surface of the conveyor is composed of a series of plates or shapes called ‘apron’, which are attached to the links of the chains through cleats. The bed created by the aprons is used for carrying bulk materials as well as unit loads. When the conveyor aprons have vertical flanges on all sides to form a pan like shape, if is specifically called a ‘pan conveyor’. Material carried by the apron is discharged over the sprockets at the driven end, and the conveyor chain with aprons comes back empty on its return journey. These are normally slow speed conveyors with a speed range of 20 meters per minute to 35 meters per minute.
Pantograph – It is a linkage which supports the current collector of an electric locomotive.
Paper – It is produced from moist fibres of cellulose pulp and dried into flexible sheets with a variety of uses.
Paper-based analytical devices (PADs) – These are low-cost, disposable platforms which use paper as a substrate to perform analytical tests, leveraging capillary action for fluid transport to enable chemical and biological assays at the point-of-need. Engineering these devices involves designing hydrophobic barriers to create microchannels and integrating different detection techniques, such as electro-chemical or colorimetric methods, to monitor health, environmental, and food safety issues.
Paper clip – It is defined as a small, typically wire-formed, fastener which uses the principles of material elasticity and torsion to temporarily hold sheets of paper together, designed with considerations for the material’s yield stress, corrosion resistance, durability, and cost-effectiveness. The design exploits the material’s inherent properties to provide a secure grip on papers without causing permanent damage, with variations including different finishes, sizes, and materials like plastic.
Paper coatings – These consist of coatings which are applied during the manufacturing process of paper to improve its finish and printability. The coating is designed to improve certain characteristics of the paper so that the finished paper product has the properties needed for its intended application, which includes its opacity, brightness, whiteness, colour, surface smoothness, gloss, and ink receptivity.
Paper marks – These are impressions of release paper, which is being used for preventing the unvulcanized belt stick to the press platens during the vulcanization process. The impressions look like small cracks on the cover surface. Normally they are abraded after a short time and do not affect the belt’s life expectancy or performance.
Papping plate – It is a metal plate attached to a pattern to prevent injury to the pattern and assist in loosening it from the sand.
Parabolic – It refers to the U-shaped curve or surface of a parabola, defined by points equidistant from a focus and a directrix, and is utilized in applications like parabolic reflectors (such as solar power collectors) and in analyzing projectile motion. The parabolic shape allows for the efficient focusing or collection of waves or particles, or for precise prediction of trajectories influenced by gravity.
Parabolic antenna – It is a type of high-gain, directional antenna which uses a curved parabolic reflector to focus or direct electro-magnetic waves. It consists of a parabolic dish and a feed antenna at the dish’s focal point. When transmitting, the feed horn reflects waves into a parallel beam and when receiving, it focuses incoming waves to the feed horn.
Parabolic dish -It is a three-dimensional, bowl-shaped reflective surface, mathematically a paraboloid, used to concentrate or project energy like light, radio waves, or heat to a single focal point. Its shape is a critical engineering feature which enables high gain and directivity by precisely focusing parallel incoming rays or creating a narrow beam of outgoing waves, making it ideal for applications such as concentrated solar power systems.
Parabolic trough solar collector – It is a type of concentrating solar thermal collector which uses a long, parabolic-shaped reflector to focus direct sunlight onto a receiver tube running along its focal line. A heat transfer fluid circulates through this tube, heating up and then transporting the thermal energy to be used for industrial processes, heating, or to generate electricity through a steam turbine.
Paradigm – It is a distinct set of concepts or thought patterns, including theories, research methods, postulates, and standards for what constitute legitimate contributions to a field.
Paradigm shift – It is frequently a change in the perception of how things are to be thought about, done, or made. A paradigm shift can replace old processes, technologies, and products with new ones eliminating industry connected with the old processes, technologies, and products. Reacting well in time to key paradigm shifts have a lot to do with the long-term success. Paradigm shift is a popular, or perhaps, not so popular shift transformation of the way the humans perceive events, people, environment, and life altogether. It can be a national or international shift, and can have dramatic effects, which can be whether positive or negative, on the way the things are being done today and in the future.
Paraffin – It is a trivial name for an alkane. It is another name for kerosene which is a combustible hydrocarbon liquid. It is derived from petroleum.
Paraffin wax – It is a soft colourless solid derived from petroleum, coal, or oil shale which consists of a mixture of hydrocarbon molecules containing between 20 and 40 carbon atoms. It is solid at room temperature and begins to melt above around 37 deg C, and its boiling point is above 370 deg C. Common applications for paraffin wax include lubrication, electrical insulation, and candles. Dyed paraffin wax can be made into crayons.
Paraformer – It is a device similar to a transformer which couples energy between two circuits by varying magnetic parameters.
Parallax error – It is a measurement error which occurs when an observer’s line of sight to a scale or instrument is not perpendicular to it, causing an apparent shift in the position of the measurement marking or object being viewed. This misalignment results in an inaccurate reading that is either higher or lower than the true value.
Parallel lines – Parallel lines are coplanar infinite straight lines which do not intersect at any point. Parallel planes are planes in the same three-dimensional space that never meet. Parallel curves are curves that do not touch each other or intersect and keep a fixed minimum distance.
Parallel circuits – If two or more components are connected in parallel, they have the same difference of potential (voltage) across their ends. The potential differences across the components are the same in magnitude, and they also have identical polarities. The same voltage is applied to all circuit components connected in parallel. The total current is the sum of the currents through the individual components, in accordance with Kirchhoff’s current law.
Parallel connection – It links multiple components side-by-side so that current splits and flows through each component, resulting in the same voltage across all of them. The total current in the system is the sum of the currents through each parallel component, while the total resistance is less than any individual resistance because there are multiple paths for current.
Paralleling three-phase transformers – Two or more three-phase transformers, or two or more banks made up of three single-phase units, can be connected in parallel for additional capacity. In addition to requirements for parallel operation of single-phase transformers, phase angular displacements (phase rotation) between high voltages and low voltages are to be the same for both. The requirement for identical angular displacement is required to be met for paralleling any combination of three-phase units and / or any combination of banks made up of three single-phase units.
Parallelism – It is a term encountered in geometric dimensioning and tolerancing (GD&T) / geometrical product specifications (GPS). It controls a requirement for two features to be geometrically parallel, within a certain acceptable tolerance. As such it is a relative control i.e., no one feature in isolation can be parallel.
Parallelism gauge – It is a dial gauge or a coordinate measuring machine for the measurement of parallelism.
Parallel laminate – It is a laminate of woven fabric in which the plies are aligned in the same position as originally aligned in the fabric roll. It is also a series of flat or curved cloth-resin layers stacked uniformly on top of each other.
Parallel offset – It means that the axes of connected shafts are parallel but not in the same straight line. It is also called radial misalignment.
Parallel operation of single-phase transformers – This is done for additional capacity. In perfect parallel operation of two or more transformers, current in each transformer is directly proportional to the transformer capacity, and the arithmetic sum is equal to one-half of the total current. In practice, this is seldom achieved because of small variations in transformers. However, there are conditions for operating transformers in parallel. In the first condition, any combination of positive and negative polarity transformers can be used. However, in all cases, numerical notations are to be followed on both primary connection and secondary connection. It is to be noted that each subscript number on a transformer is to be connected to the same subscript number on the other transformer. With positive and negative polarity transformers, the location of connections on the tanks are reversed. Hence, care is to be exercised for ensuring that terminals are connected. The second condition is that the tap settings is to be identical. The third condition is that the voltage ratings are to be identical, which, of course, makes the turns ratios also identical. The fourth condition is that the percent impedance of one transformer is to be between 92.5 % and 107.5 % of the other. Otherwise, circulating currents between the two transformers are excessive. The fifth condition is that the frequencies are to be identical. Standard frequency of 50 hertz or 60 hertz which are normally used in several countries do not present a problem. It can be noticed from the above requirements, that paralleled transformers do not have to be the same size. However, to meet the percent impedance requirement, they are to be nearly of the same size. Majority of the utilities do not parallel transformers if they are more than one standard kVA size rating different from each other, since otherwise circulating currents are excessive.
Parallel plate capacitor – It is a passive electronic component with two flat, parallel conducting plates separated by a small distance and an insulating dielectric material, designed to store electrical energy in the electric field between the plates.
Parallel plate heat exchanger – It is a compact device with a series of stacked, thin metal plates separated by gaskets to create alternating channels for hot and cold fluids. Heat transfers between the fluids through the plate walls, which have embossed patterns to increase turbulence and efficiency. These exchangers prevent fluid cross-contamination, making them suitable for applications like HVAC (heating, ventilation, and air conditioning) and cryogenic systems, though specific flow configurations (parallel, counterflow, crossflow) are determined by design to optimize heat transfer.
Parallel roller conveyor – It is a type of conveyor system which is characterized by multiple rollers aligned parallel to each other, requiring regular checks for roller health, alignment, and efficient material flow.
Parallel slide valve or parallel gate valve – Parallel slide valve or parallel gate valve is a slide valve with a parallel-faced gate-like closure member. This closure member can consist of a single disk or twin disks with a spreading mechanism in between. Parallel slid gate valve is ideal for high temperature and pressure line to prevent thermal binding.
Parallel welding – It is a resistance welding secondary circuit variation in which the secondary current is divided and conducted through the work-pieces and electrodes in parallel electrical paths to simultaneously form multiple resistance spot, seam, or projection welds.
Para-magnet – It is a body or substance which, placed in a magnetic field, possesses magnetization in direct proportion to the field strength. It is a substance in which the magnetic moments of the atoms are not aligned.
Para-magnetic material – It is a material whose specific permeability is higher than unity and is practically independent of the magnetizing force. It is also a material with a small positive susceptibility because of the interaction and independent alignment of permanent atomic and electronic magnetic moments with the applied field.
Para-magnetism – It is a property shown by substances which, when placed in a magnetic field, are magnetized parallel to the field to an extent proportional to the field (except at very low temperatures or in extremely large magnetic fields).
Parameter – It is a characteristic which can help in defining or classifying a particular system (meaning a process, event, project, object, and situation, etc.). That is, a parameter is an element of a system that is useful, or critical, when identifying the system, or when evaluating its performance, status, condition, etc. Parameter has more specific meanings within various disciplines. In statistics, parameter is a summary measure of some characteristic for the population, such as the population mean or proportion. This word occurs in its customary mathematical meaning of an unknown quantity which varies over a certain set of inputs. In statistical modelling, it most normally occurs in expressions defining frequency or probability distributions in terms of their relevant parameters (such as mean and variance of normal distribution), or in statistical models describing the estimated effect of a variable or variables on a response. Of utmost importance is the notion that statistical parameters are merely estimates, computed from the sample data, which are meant to provide insight as to what the true population parameter value is, although the true population parameter always remains unknown to the analyst. The population values are frequently modelled from a distribution. Then the shape of the distribution depends on its parameters. For example, the parameters of the normal distribution are the mean, and the standard deviation. For the binomial distribution, the parameters are the number of trials, and the probability of success. Parameter in crystal is the length of any side of a unit cell of a given crystal structure. The term is also used for the fractional coordinates, ‘x’, ‘y’, ‘z’ of lattice points when these are variable.
Parameter design – It is the second stage of the robust design process in which a robust design is achieved by optimizing performance of the system through experimentation which minimizes variation in the presence of uncontrolled user and environmental factors (noise).
Parameter estimation – In estimation theory, it is the practice of assigning values to a process model so it accurately predicts the process’s behaviour.
Parametric analysis – It is a technique to study the impact of changing specific input variables (parameters) on a system’s performance by varying one parameter at a time while keeping others constant. It involves asking ‘what if’ questions by changing design parameters, geometry, or boundary conditions to observe the effects on outputs like stress, cost, or efficiency. This allows engineers to compare different design configurations, identify design trade-offs, and understand how a product’s behaviour changes with its characteristics.
Parametric design – It is the third stage of the engineering design process, normally called detail design. In this stage of design, detailed analysis determines the final shape, dimensions, and properties of parts. Optimization methods, especially those employed in robust design are used to enhance quality. Final decisions are made on materials and manufacturing processes, and the part cost is determined.
Parameterization: In climate models, this term refers to the technique of representing processes which cannot be explicitly resolved at the spatial or temporal resolution of the model (sub-grid scale processes) by relationships between the area or time-averaged effect of such sub-grid-scale processes and the larger scale flow.
Parasitic capacitance – It is also known as stray capacitance. It is an unavoidable and typically unwanted electrical capacitance which occurs between two conductive parts of an electronic circuit simply because they are close to each other. This unintentional capacitance causes unintended charge storage, which can interfere with the normal operation of a circuit, especially at high frequencies.
Parasitic load – It refers to the energy consumed by auxiliary systems and components that are necessary for the operation of a larger system but do not contribute to its primary purpose or output, hence reducing overall efficiency. Examples include cooling fans in an engine, pumps in an electricity generation facility, or even the standby power drawn by an appliance when it is off.
Paratoluosulphonic acid (PTS) – It is used in foundries as a hardening catalyst for sand.
Para-xylene – It is an aromatic hydrocarbon. It is one of the three isomers of di-methyl-benzene known collectively as xylenes. The p– stands for para–, indicating that the two methyl groups in p-xylene occupy the diametrically opposite substituent positions 1 and 4. It is in the positions of the two methyl groups, their arene substitution pattern, that it differs from the other isomers, o-xylene and m-xylene. All have the same chemical formula C6H4(CH3)2. All xylene isomers are colourless and highly flammable. The odour threshold of p-xylene is 0.62 parts per million.
Parent coil – It is a coil which has been processed to final temper as a single unit. The parent coil can subsequently be cut into two or more smaller coils or into individual sheets or plates to provide the needed width and length.
Parent metal – It is a non-standard term for base metal.
Parent plate – It is a plate which has been processed to final temper as a single unit. The parent plate can subsequently be cut into two or more smaller plates to provide the needed width and length.
Pareto analysis – It is a decision-making technique which uses the Pareto principle (the 80/20 rule) to prioritize problems by identifying the ‘vital few’ causes which produce the ‘trivial many’ effects, thereby focusing limited resources on the most impactful areas for improvement. This method involves gathering data, arranging it into a Pareto chart, and identifying the top causes or issues that contribute to the majority of problems, such as the few component defects causing most operational faults or the few significant features providing most system value.
Pareto chart – It is a quality tool which combines a bar and line graph to visually identify and prioritize the ‘vital few’ causes that contribute to the majority of a problem, based on the Pareto principle or 80/20 rule. Bars, in descending order of frequency, represent the individual causes, while a line graph shows the cumulative percentage of the total problem, helping engineers focus efforts on the most significant factors to achieve the highest improvement.
Pareto plot – It is a graphical tool, basically a combination bar and line graph, which displays the frequency or impact of different factors (like defects or causes) in descending order. It is based on the Pareto principle, which suggests that a small percentage of causes (frequently 20 %) account for a large majority of effects (frequently 80 %). The plot’s bars represent individual problem frequencies, while a cumulative line shows the total percentage, enabling engineers to identify and prioritize the ‘vital few’ issues which yield the highest improvements.
Pareto principle – It is also known as 80/20 rule. It states that around 80 % of effects (e.g., machine downtime, defects, problems) stem from only 20 % of causes (e.g., causes, inputs, raw materials). Engineers use this principle with Pareto analysis and charts to identify the ‘few’ causes which contribute most significantly to a problem, allowing them to prioritize efforts and resources to achieve the highest improvement in quality, efficiency, and problem resolution.
Paris Convention – It is the main international convention on third party nuclear liability alongside the Brussels Convention. The Paris Convention provides for compensation for injury to or loss of life of any person, and for damage to, or loss of any property caused by a nuclear accident in a nuclear installation or during the transport of nuclear substances to and from installations. It does not cover damage to the nuclear installation itself.
Parison – It is the hollow plastic tube from which a plastic component is blow molded.
Parity – It normally refers to the state of equality or equivalence between two or more things, such as people, prices, purchasing power and mathematical functions. In mathematics, parity is the property of an integer of whether it is even or odd. An integer is even if it is divisible by 2, and odd if it is not. For example, −4, 0, and 82 are even numbers, while −3, 5, 7, and 21 are odd numbers. The above definition of parity applies only to integer numbers; hence, it cannot be applied to numbers like 1/2 or 4.201.
Parkerizing – It is a proprietary method of producing a protective phosphate coating on ferrous metals. Parker is a treatment which involves immersing in a bath of acid manganese phosphate. The Parker D is a modification using acid zinc phosphate with a nitrate iron as accelerator.
Parkes process – It is a process which is used to recover precious metals from lead and based on the principle that if 1 % zinc to 2 % zinc is stirred into the molten lead, a compound of zinc with gold and silver separates out and can be skimmed off.
Park-transform – It is a mathematical technique which is useful in the analysis of three-phase systems.
Parlanti casting process – It is a proprietary permanent mould process using dies of aluminum with a controlled rate of heat transfer.
Parsons Duncan process – It is a method of casting steel ingots wherein the top layer of the mould is heated and the last to solidify.
Part – It is the designed object which has no assembly operations in its manufacture. Parts can be either standard or special purpose. 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. A special purpose part is designed and manufactured for a specific purpose in a specific product.
Part drawing – It is a detailed drawing of a component to facilitate its production. All the principles of orthographic projection and the technique of graphic representation are followed to communicate the details in a part drawing. A part drawing with production details is rightly called as a production drawing or working drawing.
Parted pattern – It is a pattern made in two or more parts.
Partial annealing – It is an imprecise term which is used to denote a treatment given cold-worked metallic material to reduce its strength to a controlled level or to effect stress relief. To be meaningful, the type of material, the degree of cold work, and the time-temperature schedule is to be stated.
Partial de-oxidation – It takes place because of insufficient additions of ferro-alloys and other deoxidizing agents in liquid steel. This results into incomplete removal of dissolved oxygen from liquid steel.
Partial discharge – It is the breakdown of insulating gas or solid material by an electric field, but without formation of an arc.
Partial graphite carbon block – It is made of calcined anthracite under high temperature and graphite. Medium pitch acts as binder. Main processes are extruding, baking and processing. Typical properties are with good thermal conductivity and anti-alkaline. Partial graphite carbon block is used in bottom of the blast furnace.
Partial joint preparation – It means joint penetration which is intentionally less than complete.
Partial (journal) bearing – It is a bearing in which the bore extends not more than half the circumference of the journal.
Partial differential equation (PDE) – It is a mathematical equation relates an unknown function of multiple variables to its partial derivatives with respect to those variables. Partial differential equations are used to model complex physical, chemical, engineering, and economic systems where quantities depend on several factors, such as space and time. An example is the wave equation, which describes phenomena like wave propagation and sound.
Partial hydrodynamic lubrication – It is a loosely defined regime of lubrication, especially in metal-working, where thin-film lubrication predominates.
Partial likelihood estimation – It is the estimation method for the Cox regression model. It uses only the part of the likelihood function which is based exclusively on the regression coefficients.
Partially graphitized cast iron – It is a blackheart malleable casting only partly graphitized in annealing, giving a mixture of black and white fracture.
Partially melted zone (PMZ) – In welding, it is a region of the base metal located immediately adjacent to the fusion zone (FZ), where partial melting occurs because of the heat from welding. This melting is frequently caused by the formation of low-temperature eutectics, and can lead to grain boundary liquation, potentially weakening the material and causing cracking. The partially melted zone is situated between the fully melted fusion zone and the unaffected base metal.
Partially observable Markov decision process (POMDP) – It is a mathematical framework for decision-making under uncertainty, where an agent takes actions in an environment but only receives noisy or incomplete observations about the true underlying state. Unlike a standard Markov decision process, where the agent knows the exact state, a partially observable Markov decision process needs the agent to maintain a belief about the state based on its observations to maximize long-term expected rewards.
Partially premixed burners – In these burners a portion of the fuel is mixed with the oxidizer. This is normally done for stability and safety reasons. The partial premixing helps anchor the flame, but not fully premixing lessens the chance for flashback. This type of burner normally has a flame length and temperature and heat flux distribution which is between the fully premixed and diffusion flames.
Partially stabilized zirconia (PSZ) – It is a type of zirconium oxide (ZrO2) ceramic material which has been stabilized with an additive material, typically yttrium oxide (Y2O3), magnesium oxide (MgO), or calcium oxide (CaO). The addition of these additive materials prevents the transformation of zirconia from its tetragonal to its monoclinic phase, which can cause cracking and failure of the material. The properties of partially stabilized zirconia make it an attractive material for various industrial applications. Some of its key properties include high strength and toughness, good wear resistance, low thermal conductivity, and high thermal shock resistance.
Partial oxidation (Pox) – It is a chemical process where a fuel (like natural gas or a hydrocarbon) reacts with a limited quantity of oxygen, producing a mixture of hydrogen, carbon mono-oxide, and sometimes carbon di-oxide. This reaction is exothermic, meaning it releases heat, and is used in several applications, including hydrogen production and as a step in gasification processes. Partial oxidation occurs when a sub-stoichiometric fuel-air mixture is partially combusted in a reformer, creating a hydrogen-rich syngas which can then be put to further use, for example in a fuel cell.
Partial oxidation gasification – It is a thermo-chemical process which converts carbon-containing feedstocks, like biomass or coal, into a gaseous fuel known as syngas (mainly carbon mono-oxide and hydrogen) by reacting them with a controlled amount of an oxidant, such as air or pure oxygen, at high temperatures. It is a ‘partial’ oxidation since it uses less oxidant than needed for complete combustion, generating enough heat to drive endothermic reactions and break chemical bonds in the feedstock to produce the desired syngas mixture.
Partial premix gas burner – It is a type of burner where the fuel gas and oxidizer (normally air) are partially mixed before combustion, rather than fully mixed as in a premixed burner or not mixed at all as in a diffusion burner. This partial mixing creates a mixture with varying fuel gas-to-oxidizer ratios within the flame zone, leading to a more complex combustion process.
Partial pressure – In a mixture of gases, each constituent gas has a partial pressure which is the notional pressure of that constituent gas as if it alone occupied the entire volume of the original mixture at the same temperature. The total pressure of an ideal gas mixture is the sum of the partial pressures of the gases in the mixture. The partial pressure of a gas is a measure of thermo-dynamic activity of the molecules of the gas. Gases dissolve, diffuse, and react as per their partial pressures but not as per their concentrations in gas mixtures or liquids.
Partial regression coefficient (also known as partial slope) – It is the coefficient for a predictor in a regression model which contains more than one explanatory variable. It represents the effect of that predictor controlling for all other predictors in the model.
Participatory management – It is a management approach where employees at all organizational levels are actively involved in decision-making processes to leverage their knowledge and motivate them for better performance and productivity. This approach shifts from traditional vertical structures by empowering employees to contribute ideas, skills, and opinions, fostering a more engaged, innovative, and fulfilling work environment.
Particle – It is a minute portion of matter. A metal powder particle can consist of one or more crystals.
Particle accelerator – It is a device which raises the velocities of charged atomic or sub-atomic particles to high values.
Particle composite material – It is a type of composite material where small particles are dispersed within a matrix material to enhance the overall properties of the composite. These particles, which can be of different shapes and sizes, act as reinforcement, improving strength, stiffness, and other properties of the matrix material. Concrete and cermets are common examples of particulate composites, where aggregate is embedded in a cement matrix and ceramic particles are embedded in a metal matrix, respectively.
Particle finite element method (PFEM) – It is a numerical technique which combines the Lagrangian (particle-based) description of motion with the finite element method (FEM) to simulate problems with evolving geometries and large deformations, such as fluid-structure interaction. It uses a moving set of particles to discretize the computational domain, applies the finite element method to solve the governing equations on a dynamically updated mesh connecting these particles, and employs efficient remeshing techniques to handle large material deformations, fragmentation, and topological changes.
Particle image velocimetry (PIV) – It is a non-intrusive optical technique in fluid mechanics which quantifies instantaneous velocity fields within a transparent fluid by tracking the displacement of microscopic particles illuminated by a laser sheet. The method involves seeding the fluid with tracer particles, illuminating a plane of the flow with a pulsed laser, capturing images of the particles’ movement with a high-speed camera, and then using image cross-correlation to determine the velocity vectors of the fluid flow.
Particle impact angle – It is the angle between the particle’s velocity and the surface it strikes, or a surface it encounters, such as the wall of a pipe. This angle is a crucial parameter in fields like pneumatic conveying and erosion studies since it influences considerably outcomes like particle degradation and material wear.
Particle impact noise detection (PIND) – It is a test which is designed to identify the presence of loose particles inside a device cavity that can impact the functionality, reliability or even personal safety. The particle impact noise detection test provides a non-destructive means of identifying those devices containing unattached particles with sufficient mass which, upon impact with the device case or enclosure, excite the transducer and produce a signal for detection.
Particle growth – It take place in three stages namely nucleation, coalescent coagulation, and agglomeration.
Particle hardness – It is the hardness of an individual particle as measured by a Knoop or Vickers type micro-hardness indentation test.
Particle-induced X-ray emission – It is a method of trace elemental analysis in which a beam of ions (normally protons) is directed at a thin foil on which the sample to be analyzed has been deposited. The energy spectrum of the resulting x-rays is measured.
Particle morphology – It is the form and structure of an individual particle.
Particle-reinforced metal-matrix composite – It consists of the materials produced which are produced by adding reinforcement in the form of particles (ceramic or metal), fibres, whiskers or even a sheet metal to a metal or alloy matrix. It is a material where small particles of a reinforcing material are dispersed within a metallic matrix, creating a composite material with improved mechanical properties like increased strength, stiffness, and wear resistance compared to the base metal alone. It is essentially a metal matrix composite where the reinforcing phase is in the form of discrete particles.
Particle shape – It is the appearance of a metal particle, such as spherical, rounded, angular, acicular, dendritic, irregular, porous, fragmented, blocky, rod, flake, nodular, or plate.
Particle size – It is the controlling lineal dimension of an individual particle as determined by analysis with screens or other suitable instruments. Particle size is also a measure of dust size, expressed in micro-meters or per cent passing through a standard mesh screen.
Particle size analysis – It consists of particle size distribution, normally expressed as the weight percentage retained on each of a series of standard screens of decreasing mesh size and the percentage passed by the screen of finest size. It is also called screen classification or sieve analysis.
Particle size distribution – It is the percentage, by weight or by number, of each fraction into which a powder or sand sample has been classified with respect to sieve number or particle size.
Particle size range – It consists of the limits between which a variation in particle size is allowed.
Particle sizing – It means segregation of granular material into specified particle size ranges.
Particle spacing – It is the distance between the surfaces of two or more adjacent particles in a loose powder or a compact.
Particle-stimulated nucleation (PSN) – It is a recrystallization mechanism where large second-phase particles in a deformed alloy act as nucleation sites for new grains during annealing or other heat treatments. This process is driven by the high density of dislocations and local lattice rotations that form around these particles during deformation.
Particle strengthening – It is a common form of strengthening in metals, in which small second-phase particles are distributed in a ductile matrix. Examples are precipitation-hardening (age-hardening) systems and dispersion-hardened alloys.
Particle suspension – It is a type of heterogeneous mixture where solid particles are dispersed within a fluid medium (liquid or gas), but these particles do not dissolve. Since the particles are relatively large and do not dissolve, they eventually settle to the bottom of the container over time because of the gravity if left undisturbed, a process called sedimentation. Examples include muddy water, where dirt particles are suspended in water, or a chalk and water mixture.
Particulate composite – It is the material which consist of one or more constituents suspended in a matrix of another material. These particles are either metallic or non-metallic.
Particulate filter respirators – These consist of a face piece and a filter unit. Filters of various pore sizes are available for different type and size of particulate matter. They do not offer any protection against gases or vapours and are generally used for non-emergency exposures.
Particulate fluidization – It is a state in which solid particles are individually suspended and uniformly dispersed in a fluid (gas or liquid), leading to a homogeneous bed which expands smoothly without forming bubbles. structure and increased particle-to-fluid contact, making it desirable for chemical reactions.
Particulate loading – It is the quantity of particles in a given volume of air or water. It is normally measured in milligrams per litre.
Particulate matter (PM) – Particulate matter is also known as aerosols and is a term used to describe very small solids. Smoke, ash, soot, dust, metals, and other particles from burning fuels are examples of some of the materials which make up particulate matter. It can consist of hundreds of different chemicals, including carbon, sulphur, nitrogen, and metal compounds. In fact, it refers to everything emitted in the form of a condensed (liquid or solid) phase. Particulate matter originates from several different sources, including construction sites, vehicle exhausts, industrial plants, unpaved roads, and come in many shapes and sizes. Some are large enough to be seen with the naked eye, whereas others can only be seen through powerful microscopes. Particulate matter in the atmosphere typically measures between 0.01 micrometers to 10 micrometers in diameter. Majority of the particulate matter is found in the lower troposphere, where it has a residence time of a few days. The particulate matter is removed when rain or snow carries it out of the atmosphere or when larger particles settle out of suspension because of the gravity. Large particulate matter particles (normally 1 micrometer to 10 micrometers in diameter) are generated when winds blow sea salt, dust, and other debris into the atmosphere. Fine particulate matter particles with diameters less than 1 micrometer are mainly produced when precursor gases condense in the atmosphere. Major components of fine particulate matter are sulphate, nitrate, organic carbon, and elemental carbon.
Particulate matter-10 (PM10) – It is that particulate matter which measures 10 micrometers or less.
Particulate matter-2.5 (PM2.5) – It is the particulate matter which measures 2.5 micrometers or less. It is a major pollutant source which is generated by smoke from wildfires, prescribed burns and fireplace activity.
Particulate matter emissions – These are emissions which mean the release of tiny solid or liquid particles into the atmosphere from sources like vehicles, industry, and natural events. These particles, which include soot, dust, and aerosols, are categorized by size (e.g., PM10, PM2.5) and are a significant component of air pollution, posing risks to health and the environment.
Particulate reinforced ceramic-matrix composite – It is a ceramic-matrix composite in which the reinforcing components are particles of equiaxed or platelet geometry (in contrast to whiskers or short fibres).
Particulate removal – It consists of the removal of particulate air pollutants from their gaseous media by using gravitational, centrifugal, electro-static and magnetic forces, thermal diffusion, or other techniques.
Particulates – These are microscopic particles of solid or liquid matter suspended in the air. The term aerosol refers to the particulate / air mixture, as opposed to the particulate matter alone, though it is sometimes defined as a subset of aerosol terminology. Sources of particulate matter can be natural or anthropogenic. They have impacts on climate and precipitation which adversely affect human health, in ways additional to direct inhalation.
Particulate silica – It refers to fine particles of silicon di-oxide (SiO2) which can occur in both crystalline and amorphous forms, such as silica dust, silica fume, or silica nano-particles. These fine particles are generated from different natural and industrial processes, including the grinding of rocks containing quartz or the production of cement.
Parting – In the recovery of precious metals, it is the separation of silver from gold. It also the zone of separation between cope and drag portions of the mould or flask in sand casting. It is a composition sometimes used in sand moulding to facilitate the removal of the pattern. It is the joint, dividing line, where mould separates to permit removal of the pattern. It is the cutting simultaneously along two parallel lines or along two lines that balance each other in side thrust. It is also a shearing operation used to produce two or more parts from a stamping.
Parting agent – It is a lubricant, liquid, or powder (frequently silicone oils and waxes) which is used to prevent sticking of moulded articles in the cavity.
Parting compound – It is a material dusted or sprayed on foundry (casting) patterns to prevent adherence of sand and to promote easy separation of cope and drag parting surfaces when the cope is lifted from the drag.
Parting line – It is a mark on a moulded piece where the sections of a mould have met in closing. It is the intersection of the parting plane of a casting or plastic mould or the parting plane between forging dies with the mould or die cavity. It is a raised line or projection on the surface of a casting, plastic part, or forging that corresponds to said intersection.
Parting plane – In forging, it is the dividing line between dies. It is the plane which includes the principal die face and is perpendicular to the direction of ram travel. When parting surfaces of the dies are flat, the parting plane coincides with the parting line. In casting, it is the dividing line between mould halves.
Parting sand – In foundry practice, it is a fine sand for dusting on sand mould surfaces which are to be separated.
Partition coefficient – It is the ratio of concentrations of a compound in a mixture of two immiscible solvents at equilibrium. This ratio is hence a comparison of the solubilities of the solute in these two liquids. The partition coefficient normally refers to the concentration ratio of un-ionized species of compound, whereas the distribution coefficient refers to the concentration ratio of all species of the compound (ionized plus un-ionized).
Partitioning – It refers to the act of dividing a system, process, data, or physical space into smaller, distinct components to improve efficiency, manage complexity, or achieve separation. The specific application dictates the type of partitioning namely data partitioning organizes datasets, chemical partitioning distributes solutes between phases, partition walls divide physical spaces, and partitioning in computing allocates resources or processes.
Partitions – Partition consist of a sectioning device within a container. Partitions can be corrugated, scored or interlocking. They provide cushioning as well as separation.
Partnership – It is a relationship in which individuals or organizations share resources and responsibility to achieve a common objective, as well as any resulting rewards or recognition. It frequently includes a formal contract, new resources and shared risks and rewards. The structure includes a central body of decision-makers whose roles are defined. The links are formalized. Communication is frequent, the leadership is autonomous and the focus is on specific issues. Partnerships are a form of collaboration.
Parts accumulator – It is a component in a conveyor system which temporarily holds and accumulates products or materials, necessitating periodic inspections for proper functioning and capacity management.
Parts conveyor – It is the conveyor system which is used to catch and gather smaller parts and debris away from the production areas in a warehouse.
Parts list – It is also called bill of materials. It is a document which is used to track the parts in an assembly. It consists of the part number, part name, and quantity needed for the complete assembly. It can also contain information on procurement tracking or special assembly instructions.
Parts per billion – It is a measure of proportion by weight, equivalent to one unit weight of a material per billion (10 to the power 9) unit weights of compound. One part per billion is equivalent to 1 nanogram per gram.
Parts per million – It is a measure of proportion by weight, equivalent to one unit weight of a material per million (10 to the power 6) unit weights of compound. One part per million is equivalent to 1 milligram per kilograms. Parts per million means that how many parts a certain molecule or compound makes up within the one million parts of the whole solution. It is typically used to describe concentrations of chemicals dissolved in a solvent (typically water) or compounds in soil.
Pascal – It is the unit of pressure in the International System of Units (SI). It is also used to quantify internal pressure, stress, Young’s modulus, and ultimate tensile strength. The unit is an SI coherent derived unit defined as one newton per square metre.[
Pascal’s law – It is a principle in fluid mechanics which states that a pressure change at any point in a confined incompressible fluid is transmitted throughout the fluid such that the same change occurs everywhere.
Pascal’s principle – It is defined as ‘a change in pressure at any point in an enclosed incompressible fluid at rest is transmitted equally and undiminished to all points in all directions throughout the fluid, and the force due to the pressure acts at right angles to the enclosing walls.
Pass – It is a single transfer of metal through a stand of rolls. It is also the open space between two grooved rolls through which metal is processed. It is also the weld metal deposited in one trip along the axis of a weld. In boiler terminology, pass is a confined passage-way, containing heating surface, through which a fluid flows in essentially one direction.
Passivation – It is a reduction of the anodic reaction rate of an electrode involved in corrosion. It is also the process in metal corrosion by which metals become passive. It is the changing of a chemically active surface of a metal to a much less reactive state. It is also the formation of an insulating layer directly over a semiconductor surface to protect the surface from contaminants, moisture, and so forth.
Passivator – It is a type of corrosion inhibitor which appreciably changes the potential of a metal to a more noble (positive) value.
Passive – It is a metal corroding under the control of a surface reaction product. It is also the state of the metal surface characterized by low corrosion rates in a potential region which is strongly oxidizing for the metal.
Passive-active cell – It is a corrosion cell in which the anode is a metal in the active state and the cathode is the same metal in the passive state.
Passive air preheaters – These preheaters are gas to gas heat recovery devices for low to medium temperature applications where cross contamination between gas streams are required to be prevented. Passive preheaters are usually of two types namely (i) the plate type and (ii) the heat pipe type. The plate type preheater consists of multiple parallel plates which create separate channels for hot and cold gas streams. Hot and cold flows alternate between the plates and allow significant areas for heat transfer. The heat pipe heat exchanger consists of several pipes with sealed ends. Each pipe contains a capillary wick structure which facilitates movement of the working fluid between the hot and cold ends of the pipe. Hot gases pass over one end of the heat pipe causing the working fluid inside the pipe to evaporate. Pressure gradients along the pipe cause the hot vapour to move to the other end of the pipe, where the vapour condenses and transfers heat to the cold gas. The condensate then cycles back to the hot side of the pipe through capillary action.
Passive design – It uses natural ambient energy sources and design strategies like orientation, insulation, thermal mass, shading, and natural ventilation to create comfortable, energy-efficient buildings by reducing or eliminating the need for mechanical heating, cooling, and lighting systems. Its goal is to achieve human comfort using minimal purchased energy, promoting sustainability and reducing greenhouse gas emissions.
Passive device – It is an electronic component or system which cannot generate power, amplify signals, or control the flow of electricity by another electrical signal. Instead, it can only store, dissipate, or transfer energy. Common passive devices in electrical circuits include resistors, capacitors, and inductors. They do not need an external power source to operate, and they can be connected in either direction within a circuit.
Passive extreme pressure – These are extreme pressure additives which function by adsorbing a film of carbonate particles at the tool-work-piece interface in metalworking operations. These films have low shear strengths and high melting points. They reduce friction and minimize metal transfer from the work-piece to the tool. Passive extreme pressure additives do not contain phosphorus, sulphur, or chlorine, but are synergistic with sulphur containing extreme pressure additives. They offer advantages over conventional extreme pressure additives in that they are less corrosive, are more easily disposed of after use, are low foaming, and are easily cleaned from the work-piece surface. They can be used with both ferrous and non-ferrous metals.
Passively safe – It is a passively safe facility can be safely shut down automatically, without any operator intervention and without any external power supply from the grid or from backup generators to drive instruments or equipment.
Passive roller – It consists of a conveyor system where rollers are arranged perpendicular to the direction of material flow, needing routine checks for roller health, alignment, and efficient material movement.
Passive tag – It is a wireless device, normally an RFID (radio-frequency identification) tag, that does not have an internal power source (like a battery). Instead, it receives energy from the radio-frequency identification reader’s radio waves to power its internal circuitry and transmit data back to the reader. Passive tags are typically smaller, lighter, more cost-effective, and have a shorter read range than active tags, making them ideal for tracking items in applications like retail inventory and access control.
Passivity – It is a condition in which a piece of metal, because of an impervious covering of oxide or other compound, has a potential much more positive than that of the metal in the active state.
Paste – It refers to a mixture of solid particles (like cement, tailings, or solid lubricants) suspended in a liquid or binder, resulting in a viscous, frequently non-Newtonian fluid with properties like the ability to flow, act as an adhesive or lubricant, and fill gaps. The specific composition and resulting rheological properties of a paste, such as its flow characteristics and consistency, determine its application in different fields, including construction (cement paste), mining (paste backfill), and electronics (solder paste).
Paste adhesive – It is a type of high-viscosity adhesive, similar to a thick paste, designed to bond surfaces together by adhering strongly to them and resisting separation. Its high viscosity prevents dripping or sagging when applied, making it suitable for use on vertical surfaces. Paste adhesives also have the functional advantages of acting as a gap filler and a sealant, which are useful in different repairs, and industrial applications.
Paste compound – It is a metal powder mixed with a thin binder for use as a brush-on brazing filler metal.
Pasteurization – It is a method in which the micro-organisms are killed by heat treatment, and usually involves the application of temperature below 100 deg C. The heating can be generated by hot water, dry heat, or electric current, and products are rapidly cooled at 4 deg C just after the heat treatment. Industrial methods using pasteurization utilize two approaches namely (i) utilization of a high temperature for a short time, or (ii) a low temperature for a longer time.
Patch cables – These are short cables with connectors, which are used to make connections between outlets of a patch panel or for temporary connections to a system under test.
Patching – It means repair of a furnace lining or repair of a mould core.
Patch repair – It is a method for fixing localized damage in a structure by applying a new material (the patch) over the compromised area, restoring functionality and integrity without replacing the entire component. This technique involves removing the damaged or deteriorated material, preparing the surface, and then bonding or filling the area with a suitable repair material, such as cementitious mortars, composite materials, or resinous materials, depending on the application and structure type. The goal is to carry loads through the repaired section and extend the structure’s life.
Patent – It is a grant made by a government to inventors which permits them the sole right to make, sell, and use the invention for a period of time.
Patent drawing – When new equipments or devices are invented, patent drawings come into existence, to illustrate and explain the invention. These are normally axonometric drawings and are to be self-explanatory. It is necessary that the patent drawings are mechanically correct and include complete information of every detail of the invention. However, these drawings are not useful for production purposes. The salient features on the drawing are numbered for identification and complete description
Patenting – In wire-making, it is a heat treatment applied to medium-carbon or high-carbon steel before drawing of wire or between drafts. This process consists of heating to a temperature above the transformation range and then cooling to a temperature below Ae1 temperature in air or in a bath of molten lead or salt.
Patent 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.
Path – It is a sequence of activities which follows a set of arcs from the start node to the finish node of a network. It is a route through a project network. The length of the path is defined as the sum of the durations of the activities of the path.
Pathogenic bacteria – These are the bacteria capable of causing disease in a host, frequently by invading tissues, reproducing within the host’s body, and producing harmful substances like toxins. They are significant in water quality monitoring, where their presence indicates potential ecological instability and health risks.
Pathogens – These are micro-organisms which cause, or can cause, disease. Communicable diseases can be transmitted by the pathogenic organisms in wastewater.
Pathway – It a line of communication over interconnecting two places or terminals. It is also a way or a course of action for achieving a specified result.
Patina – It is the coating, normally green, which forms on the surface of metals such as copper and copper alloys exposed to the atmosphere. The term is also used to describe the appearance of a weathered surface of any metal.
Pattern – It is a form of wood, metal, or other material around which moulding material is placed to make a mould for casting metals. It is an original used as a form to produce duplicate pieces. Pattern dimensions are slightly enlarged to counteract the shrinkage of the casting as it solidifies and cools in the mold. Although patterns can be made in one piece, a complicated casting may consist of two or more parts. Pattern is also a form of wax-base or plastic-base material around which refractory material is placed to make a mould for casting metals. It is a full-scale reproduction of a part used as a guide in cutting. In statistics, pattern is a characteristic of data. A good statistical analysis is one which takes account of all the ‘pattern’ in the data. In inference this can be expressed or ‘modelled’ as data = pattern + residual. The idea is that the data has variability, i.e., the values differ from each other. Some of the variability can be understood, and hence, it is part of the ‘pattern’ or ‘signal’ in the data. What is left over is not understood and is called the residual, (or ‘noise’ or ‘error’). A good analysis is one which explains as much as possible. Hence if one can still see any patterns in the residual part, then consider how it can be moved over into the pattern (or model). Even with a descriptive-statistics, it is important that the analysis reflects the possible patterns in the data. At least the obvious patterns in the data are to be considered when doing the analysis. In case of X-rays, pattern is the spatial arrangement and relative intensities of diffracted beams.
Pattern coating – It is the coating material applied to wood patterns to protect them against moisture and abrasion of moulding sand.
Pattern draft – It is the taper allowed on the vertical faces of a pattern to permit easy withdrawal of the pattern from the mould or die.
Patterned light – It refers to the visible arrangement and distribution of illumination, creating discernible shapes, lines, or shadows on a surface or within a space. It can describe the light’s physical form, such as a projected diffraction pattern, the designed distribution of a headlight beam, or the shadows cast by a light source on a subject in a photograph.
Pattern layout – It is full-sized drawing of a pattern showing its arrangement and structural features.
Pattern letters – These are metal or plastic letters or figures in different sizes which are affixed to patterns for identification purposes.
Patternmaker – Patternmaker is a craftsman engaged in production of foundry patterns from wood, plastic, or metals, such as aluminum, brass, etc.
Patternmaker’s shrinkage – It is the shrinkage allowance made on all patterns to compensate for the change in dimensions as the solidified casting cools in the mould from freezing temperature of the metal to room temperature. Pattern is made larger by the quantity of shrinkage characteristic of the particular metal in the casting and the quantity of resulting contraction to be encountered. Rules or scales are available for use.
Patternmaking – It is the highly skilled creation of an accurate, physical model or pattern of a part, frequently made oversized to account for material shrinkage, which then serves as a template to create moulds for casting or vacuum forming a final product. This process bridges design and manufacturing, allowing for the mass production of intricate metal, glass, ceramic, or fiberglass components through methods like casting or vacuum forming.
Pattern shrinkage – It is the shrinkage allowance made on all patterns to compensate for the change in dimensions as the solidified casting cools in the mould from freezing temperature to room temperature. Pattern is made larger by the quantity of shrinkage characteristic of the particular metal in the casting and the quantity of resulting contraction to be encountered. Rules or scales are available for use.
Pattern, split – Pattern are normally made in two parts, sometimes in more than two.
Patterned sheet – It consists of raising a design in relief against a surface.
Pawl – It is a movable lever which engages a fixed component to either prevent movement in one direction or restrain it altogether. As such, it is a type of latch and can also be considered a type of dog. It typically consists of a spring-loaded lever which engages a mating component at a steep enough angle to restrain it. Pawls are frequently tapered, being widened at their pivot for anchoring and narrow at their tip.
Payback period – It refers to the time needed to recoup the funds expended in an investment, or to reach the break-even point.
Payload – It is the part of a vehicle or system which performs the main mission or function and is carried by it, excluding the vehicle’s own operational components. This definition varies by field such as for a satellite, the payload is the scientific instruments, for a cargo truck, it is the goods being transported, and in computer networks, it is the actual data being sent, separate from the network protocol’s header information.
Payload ratio – It is a measure of efficiency which indicates the proportion of a vehicle’s or system’s mass that is dedicated to carrying the useful cargo, or ’payload’. It is calculated as the payload mass divided by the total mass of the system, and a higher ratio signifies higher efficiency in carrying a given payload for a specific mission.
Payment – A payment is the transfer of wealth from one party (such as a person or organization) to another. A payment is normally made in exchange for the provision of goods, services or both or to fulfill a legal obligation.
Payne effect – It is observed under cyclic loading conditions with small strain amplitudes, and is manifest as a dependence of the viscoelastic storage modulus on the amplitude of the applied strain.
Pb concentration – It is a measure of the quantity of lead (Pb) present in a specific sample or medium, such as soil, or water. It indicates the level of lead contamination and is typically quantified in units like micrograms per gram or milligrams per kilogram
p-chart – In statistical quality control, p-chart is a type of control chart which used to monitor the proportion of non-conforming units in a sample, where the sample proportion non-conforming is defined as the ratio of the number of non-conforming units to the sample size ‘n’. The p-chart only accommodates pass / fail type inspection as determined by one or more go-no go gauges or tests, effectively applying the specifications to the data before they are plotted on the chart. Other types of control charts display the magnitude of the quality characteristic under study, making troubleshooting possible directly from those charts.
PDCA cycle – PDCA stands for plan, do, check, and act. PDCA cycle is a project management frame-work which organizations can use to implement incremental change. It is a four-step approach which is the most widely used methodology for implementing continuous improvement. That is why the four steps are arranged in a circle. Organizations which take this approach aim to continually repeat the process, always identifying new opportunities to use the cycle to improve.
Pd cathode – It is an electrode made of palladium (Pd) used in electro-chemical applications, such as fuel cells and batteries, to catalyze reactions like the oxygen reduction reaction or to absorb deuterium (isotope of hydrogen). As a cathode, it is the site where reduction occurs and electrons are gained, or where negative charge flows into the electrolyte.
PDES / STEP – It is a standard data protocol for the transfer of digital data between different software and machines. PDES is more comprehensive than the Initial Graphics Exchange Standard (IGES) in that it includes product attributes such as material type and form features in addition to solid model topology.
P-diagram – It is also known as a parameter diagram. It is a graphical tool used in quality management, particularly in Failure Mode and Effects Analysis (FMEA), to visually represent the inputs (signal factors) to a system, how they interact with potential noise factors, and how they ultimately affect the desired outputs, helping to identify critical control points and design robust systems against variations and potential failures. It is essentially mapping out the relationship between controlled and uncontrolled variables that influence a system’s function. Key aspects of a P-diagram methodology include (i) identifying system boundaries, (ii) defining the ideal function, (iii) identifying control factors, (iv) identifying noise factors, and (v) mapping interactions.
Peak demand – It is the maximum rate at which energy is consumed from an electrical grid. It can be either an instantaneous measure or the maximum energy transferred in some interval such as 15 minutes.
Peak overlap – It is the formation of a single peak when two closely spaced X-ray peaks cannot be resolved; the energy (or wave-length) of the peak is some average of the characteristic energies (or wave-lengths) of the original two peaks.
Pearlite – Pearlite is a mixture of ferrite and cementite in which the two phases are formed from austenite in an alternating lamellar pattern. It is a metastable lamellar aggregate of ferrite and cementite resulting from the transformation of austenite at temperatures above the bainite range. Formation of pearlite needs relatively slow cooling from the austenite region and depends on the steel composition. Pearlite forms at temperatures below the lower critical temperature of the steel in question and can be formed isothermally or by continuous cooling. As the hardenability of the steel decreases, the cooling rate can be increased without the formation of other constituents. As isothermal reaction temperature decreases or the cooling rate increases, the inter-lamellar spacing decreases. The strength and toughness of pearlitic steels increase as the inter-lamellar spacing decreases.
Pearlite micro-structure – It is a composite microstructure in iron and steels which consists of alternating, thin layers of two distinct phases namely ferrite (alpha-iron), a soft and ductile iron-carbon solid solution, and cementite (Fe3C), a hard and brittle iron carbide. This lamellar (layered) structure forms through a eutectoid reaction during the slow cooling of austenite, the high-temperature gamma phase of iron. The characteristic pearly appearance under a microscope gives the micro-structure its name.
Pearlitic malleable iron – It is a cast iron made by prolonged annealing of white iron in which decarburization, graphitization, or both take place to eliminate some or all of the cementite. The graphite is in the form of temper carbon. If decarburization is the predominant reaction, the product shows a light fracture surface, hence whiteheart malleable. Otherwise, the fracture surface is dark, hence blackheart malleable. Ferritic malleable has a predominantly ferritic matrix. Pearlitic malleable can contain pearlite, spheroidite, or tempered martensite, depending on heat treatment and desired hardness.
Pearlitic stainless steel – It is a type of steel which has a pearlitic lattice structure. This type of steel is known for its excellent thermal stability and outstanding resistance to corrosion, making it ideal for use in industrial settings which expose it to harsh environments, such as high temperatures, high pressures, and strong corrosion. Because of its exceptional performance, pearlitic stainless steel is used in several fields, including aviation, aerospace, nuclear industry, petrochemical, medical equipment, and more.
Pearlitic steel – It is a steel with pearlitic microstructure which is normally found in steels having around 0.8 % carbon. It is characterized by a layered structure of ferrite and cementite (an iron carbide compound). While pearlite can be found in plain carbon steels, the term ‘pearlitic steel’ frequently refers to steels where this microstructure is intentionally developed and utilized for its desirable mechanical properties.
Pearlitic structure – It is a micro-structure which is resembling that of the pearlite constituent in steel. Hence, it is a lamellar structure of varying degrees of coarseness.
Pearlitic transformation – It is a diffusion-controlled process in iron-carbon alloys where high-temperature austenite decomposes into a lamellar (layered) microstructure of ferrite and cementite upon slow cooling below the eutectoid temperature. This transformation needs the cooperative diffusion of carbon atoms to form distinct layers of carbon-poor alpha ferrite and carbon-rich cementite, resulting in a two-phase micro-structure with properties different from the initial austenite.
Pearl mill – It is also known as a bead mill or sand mill. It is industrial grinding equipment which uses small beads or ‘pearls’ to reduce the particle size of several materials, especially in liquids. It operates by creating high shear forces between the beads and the material within a grinding chamber, making it essential for industries like paint and coatings to achieve desired particle fineness and efficiency.
Pearson correlation coefficient (r) – This is a measure of the correlation or linear relationship between two variables ‘x’ and ‘y’, giving a value between +1 and −1 inclusive. It is widely used in the sciences as a measure of the strength of linear dependence between two variables.
Pearson’s linear correlation coefficient (r) – It is a statistical measure which quantifies the strength and direction of a linear relationship between two continuous variables. It ranges from -1 to +1, where +1 indicates a perfect positive linear relationship, -1 indicates a perfect negative linear relationship, and 0 means there is no linear relationship between the variables. This coefficient is used in different fields to identify patterns and make predictions.
Pearson’s product moment correlation coefficient – It is denoted as ‘r’ij, where i and j refer to two variables, Pearson’s product moment correlation coefficient reflects the degree of linear association between two continuous (ratio or interval scale) variables, and is bounded between +1 for perfect positive correlation and –1 for perfect negative correlation.
Peat – It occurs in waterlogged areas, such as swamps or bogs, where plant matter is accumulated and buried by sediment, then compacted.
Peat-land – It is permanent wetlands characterized by a bed made of highly organic soil (higher than 50 % combustible) composed of partially decayed plant material.
Peat soil – It refers to a type of soil which is formed through the accumulation and decomposition of organic materials under waterlogged conditions with a lack of oxygen. It has a high organic content, typically above 75 %, and shows a dark brown to black colour with a spongy consistency.
Pebble bed reactor (PBR) – It is a graphite-moderated, gas-cooled nuclear reactor design characterized by spherical fuel elements (‘pebbles’) which continuously move through the core, providing fuel and removing spent material. These reactors, frequently of the ‘Generation IV Very-High-Temperature Reactor (VHTR) class’, use highly resistant TRISO (tri-structural isotropic) fuel particles encased in a graphite matrix and are cooled by a helium gas, leading to improved safety and high thermal efficiency for power generation.
Pebbles – The preferred term is orange peel which means a surface roughening in the form of a pebble-grained pattern where a metal of unusually coarse grain is stressed beyond its elastic limit.
Peclet number (Pe) – It is a class of dimensionless numbers relevant in the study of transport phenomena in a continuum. It is defined to be the ratio of the rate of advection of a physical quantity by the flow to the rate of diffusion of the same quantity driven by an appropriate gradient. In the context of species or mass transfer, the Peclet number is the product of the Reynolds number and the Schmidt number (Re × Sc). In the context of the thermal fluids, the thermal Peclet number is equivalent to the product of the Reynolds number and the Prandtl number (Re × Pr).
Pedestal bearing – It is a bearing that is supported on a column or pedestal rather than on the main body of the machine.
Peel – It is free removal of burnt moulding sand from casting.
Peeling – It is the detaching of one layer of a coating from another, or from the substrate, because of poor adherence. Peeling is one of the abnormalities in the rolls. During rolling, a thin layer of oxide is formed on the roll surface within the rolling width. Partial removal of just this oxide layer is known as peeling. This peeling can be easily identified when observed as silvery circumferential streaks of parent roll material, intermingled with blue / black oxide streaks still adhering to the roll surface.
Peel ply – It is a layer of open-weave material, normally fibre-glass or heat-set nylon, applied directly to the surface of a prepreg lay-up. The peel ply is removed from the cured laminate immediately before bonding operations, leaving a clean, resin-rich surface which needs no further preparation for bonding, other than application of a primer where one is needed.
Peel strength – It is the adhesive bond strength, as in kilograms per square centimeter of width, got by a stress applied in a peeling mode.
Peel test – It is a destructive method of inspection which mechanically separates a lap joint by peeling.
Peen – It is the peening action achieved by impact of metal shot, frequently used to improve fatigue properties by putting the surface in compression. It is also the small end of a moulder’s hammer.
Peening – It is the mechanical working of metal by hammer blows or shot impingement.
Peen forming – It is a die-less, flexible manufacturing technique for forming sheet metals. It is used to make large plan-area parts which are produced in small lot sizes. Forming relies on the deformation imparted by the impact of balls, which replace conventional forming dies. Unlike shot peening, in which deformation is normally limited to very shallow depths (around 100 micrometers to 200 micro-meters) in a bulk work-piece, peen forming introduces plastic deformation to depths which correspond to a large portion of or the entire cross section of a sheet. At modest shot velocities, only the surface layers are elongated, resulting in a convex curvature of the sheet. At higher shot velocities, the entire cross section is deformed. The deformation is highest on the surface opposite to the impact surface, and, in these cases, a concave curvature is developed in the sheet. A number of major advances and new applications have recently been made. These include double-sided, simultaneous peen forming, which enables the formation of curvatures which are either more complex or with considerably smaller radii.
Peening wear– It consists of removal of material from a solid surface caused by repeated impacts on very small areas.
Peep-hole – It is a small hole in the furnace refractories which can be looked through for observation of inside of the furnace.
Pegmatite – It is a coarse-grained, intrusive igneous rock characterized by exceptionally large, interlocking crystals, typically larger than 1 centimeter, and a granitic composition of quartz, feldspar, and mica. It forms from the final, water-rich stages of a magma’s crystallization, where dissolved volatiles allow for rapid crystal growth and the formation of rare minerals, frequently within veins or dikes in other igneous rocks.
Pellet – It is similar to a shotted particle. It is generally, a small rounded or spherical solid body. In case of ironmaking, it is a type of agglomerated iron ore fines which has better tumbler index when compared with that of the parent iron ore. Pellets are widely used as a substitute of lump ore for the production of direct reduced iron and in the blast furnace for the production of hot metal.
Pelletization processes – There are several iron ore pelletizing processes/technologies which are available for the production of the pellets. Some of these are (i) shaft furnace process, (ii) straight travelling grate process, (iii) grate kiln process, (iv) cement bonded processes (Grangcold process, MIS Grangcold Process, and char process etc.), and (v) hydrothermal processes, (COBO process, MTU process, and INDESCO process etc.). However, at present, only the straight travelling grate (STG) process and the grate kiln (GK) process are more popular processes.
Pelletizer – It is a mechanical machine used to transform raw materials into small, rounded, and uniform pellets by compressing them into a specific shape and size. These machines are used across different industries to create compact and dense pellets from diverse substances like plastic, and fly ash etc.
Peltier coefficient (Pi) – It is symbolized by the Greek letter pi. It quantifies the quantity of heat energy absorbed or released at the junction of two different conductors when an electric current passes through it. It essentially represents the rate of heat transfer per unit charge, or per unit of current. The unit of the Peltier coefficient is volts (V), derived from the relation where heat (H) equals the Peltier coefficient (Pi) multiplied by the current (I) and time (t), with Pi then being H/(It). This effect is fundamental to Peltier coolers and thermoelectric generators.
Peltier effect – It is a thermoelectric phenomenon where an electric current flowing through a circuit made of two dissimilar materials causes heat to be absorbed at one junction and released at the other. This means one side of the circuit gets cooler while the other gets hotter, and reversing the current reverses the heating and cooling effects.
Peltier–Seebeck effect – It is the thermoelectric effect, movement of heat because of the electric current flow.
Pencil core – It is a core projecting to the centre of a blind riser allowing atmospheric pressure to force out feed metal.
Pencil glide -It is the glide on multiple slip planes in a common direction in all of the planes.
Pencil graphite electrode (PGE) – It is a cost-effective, carbon-based electrode made from graphite pencil leads, used as a working electrode in several electrochemical and electroanalytical applications. These electrodes are valued for their simplicity, low cost, ready availability, and disposability. While bare pencil graphite electrodes can be modified and activated for specific sensing tasks, their intrinsic properties frequently need surface treatments to improve their sensitivity, selectivity, and electron transfer for complex analyses.
Pendant group – It is an offshoot or side chain of the backbone of a polymeric molecule, especially one which is itself neither oligomeric or polymeric.
Pendants – These are the operator’s connection to the crane. They provide the controls to make the crane do the job. A pendant control hangs down from the hoist or off of a separate festoon track and allows the operator to control the crane. Although pendant controls can be used on almost any type of overhead crane, they are ideal for cranes that are in lower duty cycle classes. Because it is hardwired into the electrification system, the crane controls will always have power, so the operator doesn’t have to worry about replacing or charging batteries for a crane that doesn’t get used too often. Often, pendant controls are the preferred control method for explosion proof cranes.
Pendulum – It is a device made of a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced sideways from its resting, equilibrium position, it is subject to a restoring force because of gravity which accelerates it back toward the equilibrium position. When released, the restoring force acting on the pendulum’s mass causes it to oscillate about the equilibrium position, swinging back and forth. The time for one complete cycle, a left swing and a right swing, is called the period. The period depends on the length of the pendulum and also to a slight degree on the amplitude, the width of the pendulum’s swing. The regular motion of pendulums has been used for timekeeping and has been the world’s most accurate timekeeping technology until the 1930s.
Pendulum angle – It is also known as angular displacement. It is the angle between the pendulum’s rod and its vertical equilibrium position at any given moment. It quantifies how far the pendulum has swung from its resting position and is measured in radians or degrees. This angle determines the pendulum’s position and potential energy and is crucial for describing its motion, especially when using the small-angle approximation for simple harmonic motion.
Pendulum shears – These shears consist of cutting systems suspended in an ‘oscillating’ configuration. The cut can be performed for material which is travelling or stopped. These shears are used for cropping head end or tail end or dividing the hot input material conveyed to the rolling mill.
Penetrameter – It is a strip of metal with stepped thickness variation and with holes at varying depths. It is used in radiography to indicate the sensitivity of the radiograph.
Penetrant – It is a liquid with low surface tension used in liquid penetrant inspection to flow into surface openings of parts being inspected.
Penetrant inspection – It is a type of non-destructive inspection which locates discontinuities that are open to the surface of a metal by first allowing a penetrating dye or fluorescent liquid to infiltrate the discontinuity, removing the excess penetrant, and then applying a developing agent which causes the penetrant to seep back out of the discontinuity and register as an indication. It is suitable for both ferrous and non-ferrous materials, but is limited to the detection of open surface discontinuities in non-porous solids.
Penetrant testing – It is a non-destructive testing (NDT) method which uses a coloured or fluorescent liquid (the penetrant) to find surface-breaking defects, such as cracks and pores, in non-porous materials. The penetrant seeps into flaws through capillary action, and after excess penetrant is removed and a developer is applied, the penetrant is drawn out of the flaws, creating a visible indication of the defect. This process makes otherwise invisible hairline cracks and other surface irregularities visible for inspection.
Penetration – In founding, it is an imperfection on a casting surface caused by metal running into voids between sand grains. It is normally referred to as metal penetration. In welding, it is the distance from the original surface of the base metal to that point at which fusion ceased. In case of piles, penetration is the downward movement of the pile per blow. In shearing, blanking and piercing, penetration is the sum distance of the deformation and vertical burnish height. It is expressed as a percentage of the material thickness and is defined as the distance the punch is to travel before the metal fractures. The percentage of penetration varies with the type and hardness of the material. As the material becomes harder, the percentage of penetration decreases. Penetration increases where holes are less than 1.5 times the material thickness due to the high compressive stress in the material cut zone.
Penetration depth – It is the distance at which the strength or power of an incident wave or particle decreases to around 36.8 % (1/e) of its initial value at the surface of a material, or the maximum depth it can reach while still having substantial impact. The specific definition can vary depending on the type of wave or particle (e.g., electromagnetic waves against electrons) and the material it interacts with.
Penetration drawing – It is designed for structural, mechanical, electrical, plumbing, and fire protection systems. This drawing is dimensionally locating all sleeve / cores and shaft penetration through floors and walls including the size of the actual opening and rough-in dimensions.
Penetration hardness – It is the resistance of a material to indentation. This is the normal type of hardness test, in which a pointed or rounded indenter is pressed into a surface under a substantially static load. It is also the resistance of a solid surface to the penetration of a second, normally harder, body under prescribed conditions. Numerical values used to express indentation hardness are not absolute physical quantities, but depend on the hardness scale used to express hardness.
Penetration hardness number – It is the numerical value expressing the resistance of a body to the penetration of a second, normally harder, body.
Penetration of a grease – It is the depth in 1/10 millimeter that a standard cone penetrates the sample in a standard cup under prescribed conditions of weight, time (5 second), and temperature (25 deg C). The result depends on whether or not the grease has been subjected to shear. In unworked penetration, the grease is transferred with as little deformation as possible or is tested in its container. In worked penetration, the grease is subjected to 60 double strokes in a standard device. In prolonged worked penetration, the grease is worked for a specified period before the 60 strokes. The results can be quoted as penetration number or penetration value.
Penetration resistance – It is a measure of a material’s ability to withstand deformation or intrusion from a pointed object, frequently used to assess soil compaction and its impact on root growth or the load-bearing capacity of different materials. It is a form of hardness test, while in construction, it is a mechanical property measured by the force needed for a probe to enter a soil or a barrier.
Penetrometer – In grease technology, it is an instrument for measuring the consistency of a grease by allowing a cone to penetrate into the grease under controlled conditions.
Penning gauge – It is a type of vacuum gauge comprising a means of ionizing the gas molecules, electrodes to facilitate the collection of the positive ions formed, and means of indicating the magnitude of the collected ion current.
Pen recorder – It is a multi-pen device which produces continuous analog records by displaying data as a coloured graph of values against time, which is useful for monitoring trends and rates of change in several applications.
Penstock – It is a pipe which channels water from a dam to a turbine, equipped with valves or gates to control the water flow. It can be made of materials such as cement, poly-vinyl chloride (PVC), or steel, designed with specific dimensions to accommodate the flow rate and head.
Penta-basic – It means having five hydrogen atoms which can be replaced by metals or bases.
Pentaerythritol – It is a white, crystalline, polyhydric alcohol with the chemical formula C(CH2OH)4. It is a tetraol, meaning that it has four alcohol (hydroxyl) groups attached to a central carbon atom. Pentaerythritol is a crucial chemical intermediate used in the production of various materials like alkyd resins, explosives, and plastics.
Penta-erythritol tetra-nitrate (PENT) – It is an explosive material. It is the nitrate ester of penta-erythritol, and is structurally very similar to nitro-glycerin. Penta refers to the five carbon atoms of the neopentane skeleton.
Penta-ethylene-hexamine (PEHA) – It is a high-performance, acyclic organic polyamine with five ethylene groups and six amine groups (two primary and four secondary), making it a strong chelating agent and an organic base. It is used in applications such as epoxy curing agents, where it enhances adhesion and chemical resistance, and as a corrosion inhibitor in metalworking applications. Its ability to form stable complexes with metal ions and react with acids is key to its industrial importance.
Pentagon – It is a two-dimensional geometric shape that is a polygon with five sides and five angles. It can be regular, with all sides and angles equal, or irregular, with sides and angles of varying lengths.
Pentagrid converter – It is a type of self-oscillating vacuum tube (radio receiving valve) with five grids used as the frequency mixer stage of a superheterodyne radio receiver.
Pentenes – These are alkenes with the chemical formula C5H10. Each molecule contains one double bond within its molecular structure. Six different compounds are in this class, differing from each other by whether the carbon atoms are attached linearly or in a branched structure and whether the double bond has a cis or trans form. 1-Pentene is an alpha-olefin. Very frequently, 1-pentene is made as a byproduct of catalytic or thermal cracking of petroleum or during the production of ethylene and propylene through thermal cracking of hydro=carbon fractions. 2-Pentene has two geometric isomers namely cis-2-pentene and trans-2-pentene. Cis-2-pentene is used in olefin metathesis.
Pentlandite – It is nickel iron sulphide which is the most common nickel ore. It is a metallic, brownish-yellow sulphide mineral composed of iron and nickel, with the chemical formula (Fe,Ni)9S8. It is typically found alongside pyrrhotite in magmatic rocks.
Pentode – It is an electronic device having five electrodes. The term normally applies to a three-grid amplifying vacuum tube or thermionic valve.
Pentoxide – It is a binary compound containing five atoms of oxygen, e.g., iodine pentoxide (I2O5).
Pentyl – It is an alkyl functional group containing five carbon atoms, with the generic chemical formula C5H11. It is the substituent form of the alkane pentane.
Penultimate stage – It refers to the second-to-last stage or next-to-last phase in a series or sequence of events.
Penumbra – It is the partially shadowed outer region of a shadow, where the light source is only partially obscured, creating a transition between full light and complete darkness. It can also refer to a shadowy, indefinite, or borderline area in other contexts, such as a sunspot.
People strategy – Proper people strategy helps the management to know how people feel, behave and perform in the organization. This knowledge provides the basis to increase productivity, solve issues and celebrate achievements.
Per- – It is a prefix in IUPAC (International Union of Pure and Applied Chemistry) chemical nomenclature meaning complete, exhaustive, or extreme, as in a completely substituted hydrocarbon, or indicating the presence of a peroxy group.
Peracid – It is an acid containing an acidic peroxy group (–O–O–) e.g., periodic acid.
Percentage (pct) – It is a number or ratio expressed as a fraction of 100. It is frequently denoted using the ‘percent sign’ (%). It is a dimensionless number (pure number) which is mainly used for expressing proportions, but percent is nonetheless a unit of measurement in its orthography and usage. In statistics, percentage means that for a variable with ‘n’ observations, of which the frequency of a particular characteristic is ‘r’, the percentage is 100*r/n. For example, if the frequency of an activity is 11 times in 55 years, then the percentage is 100*11/55 = 20 % of the years. Percentages are widely used (and misused). Whenever percentages are used it is to be made clear what is the 100 %. In the example above it is the value 55.
Percentage elongation after fracture (A) – It is the gauge length elongation after fracture expressed as a percentage of the original gauge length.
Percentage deviation – It is a measurement which expresses the difference between an observed or individual value and an accepted or baseline value, as a percentage of that accepted value. It is calculated by finding the absolute difference between the two values, dividing by the accepted value, and then multiplying by 100 % to express the result as a percentage.
Percentage saturation – It is a general term for a value that indicates how much of a substance has been taken up by a system, expressed as a percentage of its maximum capacity. Common examples include air humidity (ratio of current moisture to moisture at 100 % saturation and soil moisture (percentage of pore volume filled with water).
Percent error – For testing machines, it is the ratio, expressed as a percentage, of the error to the correct value of the applied load.
Percent strain – It is a unitless measurement of material deformation expressed as a percentage, calculated by dividing the change in a material’s dimension (e.g., length) by its original dimension and multiplying by 100. It indicates how much a material has stretched or compressed relative to its initial size when a force is applied, offering a clear way to quantify the extent of deformation.
Percentile – It is the value in a distribution such that a certain percentage of cases are lower than that value. For example, the 75th percentile is the value such that 75 % of cases have lower values. The ‘p’th percentile of a list is the number such that at least ‘p’ % of the values in the list are no larger than it. So, the lower quartile is the 25th percentile and the median is the 50th percentile. One definition used to give percentiles, is that the ‘p’th is the 100/p*(n+1)’th observation. For example, with 7 observations, the 25th percentile is the 100/25*8 = 2nd observation in the sorted list. Similarly, the 20th percentile = 100/20*8 = 1.6th observation. An approximate value for the ‘p’th percentile can be read from a cumulative frequency graph as the value of the variable corresponding to a cumulative frequency of ‘r’ %. So, the lower quartile is the 25th percentile and the median is the 50th percentile. The term ‘percentile’ was introduced by Galton in 1885.
Percent theoretical density – It is also known as density ratio. It is the ratio of the determined density of a compact to the absolute density of metal of the same composition. It is normally expressed as a percentage.
Perchlorate – It is a chemical compound containing the perchlorate ion, ClO4-, the conjugate base of perchloric acid. As counterions, there can be metal cations, quaternary ammonium cations or other ions, for example, nitronium cation (NO2)+. The term perchlorate can also describe perchlorate esters or covalent perchlorates. These are organic compounds which are alkyl or aryl esters of perchloric acid. Perchlorate contamination of water endangers human health.
Perchloro-ethylene – It is also known as tetrachloroethylene, or under the systematic name tetrachloroethene, and abbreviations such as perc, and PCE. It is a chlorocarbon with the formula Cl2C=CCl2. It is a colorless, nonflammable liquid solvent with a sweet, ether-like odour. It is mainly used in industrial settings and for dry cleaning fabrics and degreasing metals.
Percolate – It means to cause (a solvent) to pass through a permeable substance in order to extract a soluble constituent.
Percolation – It is the process of a liquid slowly passing through a filter or porous material. It can also refer to the movement of water through soil and rock.
Percolating filter – It is also called trickling filter is a type of waste-water treatment system. It consists of a fixed bed of some material, such as rocks, coke, gravel, slag, poly-urethane foam, sphagnum peat moss, ceramic, or plastic media, over which sewage or other waste-water flows downward and causes a layer of microbial slime (bio-film) to grow, covering the bed of media. Aerobic conditions are maintained by splashing, diffusion, and either by forced-air flowing through the bed or natural convection of air if the filter medium is porous. The treatment of sewage or other waste-water with percolating filters is among the oldest and most well characterized treatment technologies.
Percolation reactor – It is a type of packed-bed, flow-through reactor where a solvent or liquid continuously flows through a bed of solid catalyst particles or biomass to facilitate a chemical reaction, such as hydrolysis. This continuous flow enables immediate removal of reaction products, minimizing decomposition and achieving high product concentrations. Key features include a tubular design filled with solid catalyst or material, a perforated holding basket, and a pump for liquid recirculation.
Percussion cone – It is the damage produced by contact stresses generated by mechanical contact of a hard, blunt object with a glass surface. Typically, it has the appearance of a semicircular or circular crack on the damaged surface, propagating into the glass, flaring out with increasing depth into a cone-shaped crack. It is also called impact bruise, butterfly bruise, bump check, and Hertzian crack.
Percussion welding – It is a resistance welding process which produces coalescence of abutting surfaces using heat from an arc produced by a rapid discharge of electrical energy. Pressure is applied percussively during or immediately following the electrical discharge.
PERED technology for direct reduced iron production – PERED technology is also known as ‘Persian Reduction’ technology. It is the direct reduction technology invented and patented by ‘Mines and Metals Engineering GmbH’. The PERED direct reduction process converts iron oxides, in the form of pellets or lump ore, to highly reduced product suitable for steel making. The reduction of iron oxide takes place without its melting with the help of reducing gases in solid state in a vertical shaft furnace. This technology improves the process of direct reduction for the production of direct reduced iron (DRI). The process is a gas based direct reduction process which has been developed by a team of specialists having experience in different areas of the direct reduction process to ensure that all the flows of different processes are taken care in the main process to obtain optimum and efficient results. The most popular gas used for reduction is reformed natural gas though other gases such as Corex gas and coke oven gas etc. can also be used. PERED technology lowers capital cost, water consumption, maintenance cost, and energy consumption. In PERED, the reduction process takes place at a lesser temperature due to the improved cooling methods and reduced pollutant gas emissions. With less heat, more homogeneous reducing gas, more controllable pellet feed and use of centrifugal compressors, PERED requires less water, electricity and gas to operate, alongside less operational and maintenance expenditure.
Perennial water body – It normally refers to mainly liquid fresh water, as opposed to sea and glaciers or other ice. Most frequently the term refers to running water as in perennial streams and large rivers. Simplistically a perennial water body is one which keeps full or flowing throughout the year.
Perfect combustion– It is the complete oxidation of all the combustible constituents of a fuel, utilizing all the oxygen supplied.
Perfect dislocation – It is a linear crystal defect where a perfect dislocation. It is also known as a unit lattice vector, causes a displacement of atoms within the crystal lattice, leaving behind a perfectly ordered crystal structure. This defect’s Burgers vector is equal to a lattice translation vector, and it can split into partial dislocations, which create a stacking fault.
Perfect gas – It is a gas which obeys Boyle’s law, Charle’s law and has zero heat of free expansion. It is also known as an ideal gas.
Per-fluoro-alkoxy (PFA) – It is a type of fluoropolymer similar to poly-tetra-fluoro-ethylene (Teflon), known for its exceptional chemical resistance, high temperature tolerance, and non-stick properties. It is a copolymer of tetra-fluoro-ethylene and a per-fluoro-alkyl vinyl ether, giving it excellent melt processability compared to poly-tetra-fluoro-ethylene. Per-fluoro-alkoxy is widely used in several industrial applications, including tubing, linings, and coatings, where its unique combination of properties is highly valued.
Per-fluoro-alkyl vinyl ethers – These are a class of fluorinated organic compounds characterized by a vinyl ether group (a carbon-carbon double bond attached to an oxygen atom) where the alkyl group is fully fluorinated (all hydrogen atoms are replaced by fluorine atoms). They are important precursors for making different fluoropolymers, especially those used in high-performance applications like heat and solvent resistant seals, and other specialized uses.
Per-fluoro-carbons (PFCs) – They are man-made compounds containing just fluorine and carbon. They are normally colourless, odourless non-flammable gases at environmental temperatures and for the most part chemically unreactive. They are among the six greenhouse gases to be abated under the Kyoto Protocol. These are by-products of aluminum smelting and uranium enrichment. They also replace chloro-fluoro-carbons in manufacturing semi-conductors. The Global Warming Potential of PFCs is 6,500 – 9,200 times that of carbon di-oxide.
Perfluoro-poly-alkyl-ether (PFPAE) oils – These are synthetic oils. These oils and oil-based greases have become popular since their development for spacecraft applications. Their increasing use results from their favourable properties, which include a wide-application temperature range, low vapour pressure, a good viscosity index, and general chemical inertness. Under boundary lubrication conditions, conventional hydrocarbon lubricants rely on antiwear additives to minimize the effects of metal-to-metal interaction and to extend the performance of lubricants. Unfortunately, the Perfluoro-poly-alkyl-ether oils, because of their chemical composition, show very limited solvent power and dissolve very few materials.
Perfluoro-poly-ethers (PFPEs) – These are a class of organo-fluorine compound. The main properties of perfluoro-poly-ethers are being temperature resistant between −58 deg C (215 K) and 257 deg C (530 K) (depending on specific composites), having very low outgassing compared to other fluids (vapour pressure of 0.000008 pascal) and having a dielectric strength of around 15.7 millivolt per meter. The thermal and chemical stability of perfluoro-poly-ethers along with a vapor–liquid equilibrium of 230 deg C when mixed with the right composites make it a suitable candidate for vapour phase soldering technologies.
Perforated liner – It is a pipe or sheet with pre-made holes or perforations, the specific definition depending on its application. In oil and gas wells, it is a wellbore tubular with holes to allow reservoir fluids to flow into the wellbore.
Perforated panel – It is a sheet or plate, frequently made of metal like steel or aluminum, which has a pattern of holes, slots, or other shapes mechanically punched, stamped, or cut into its surface. These openings allow for passage of light, air, and sound while maintaining the panel’s structural integrity, and can be customized in size, shape, and density for specific aesthetic and functional purposes.
Perforated plate – It is a sheet of metal or other material that has a pattern of holes or slots punched, drilled, or cast into it, creating a screen-like surface for different applications such as ventilation, filtration, sound reduction, and heat dissipation. The specific material, shape, and pattern of the perforations determine the plate’s function and suitability for different uses, ranging from architectural designs to industrial processes.
Perforating – It is a more specific term used in the stamping industry for die cutting of holes in material. It is the punching of several holes, normally identical and arranged in a regular pattern, in a sheet, work-piece blank, or previously formed part. The holes are normally round, but can be of any shape. The operation is also called multiple punching.
Perforations – These are small holes in a material which are organized in a fashion making it easier for consumers to open.
Performance – It is defined as the action or process of carrying out or accomplishing an action, task, or function. It is the act of performing, of doing something successfully, and the use of knowledge as distinguished from merely possessing it. Performance involves several factors, such as task performance and contextual performance. Task performance is evaluated based on the objectives, contextual performance reveals the softer skills, such as relationship with coworkers, with customers or ability to solve problems.
Performance analysis – It is the systematic evaluation of performance using data to measure efficiency and effectiveness, identify strengths and weaknesses, and ultimately improve outcomes. It involves collecting and analyzing data through metrics and ‘key performance indicators’ (KPIs) to understand how well something (like a person, process, or organization) is doing against its goals, with the aim of making data-driven decisions for future improvement.
Performance assessment – It is the linkage of inputs (e.g., funding, manpower, equipment, and supplies), actions (e.g., advice, projects, programmes, and services) and outputs (e.g., reports, plans, policies, and products) to outcomes or results (e.g., an increase in awareness, a change in behaviour, or the achievement of an outcome or end result, such as a healthy environment).
Performance based incentive – It refers to performance-based pay programmes where an employee is incentivized and rewarded for achieving higher goals and objectives. Organizations have several incentives with some tying pay to individual performance and some pay to organization wide performance.
Performance constraint – It is a restriction, limitation, or requirement which sets boundaries on a system’s performance, frequently related to its capabilities, resources, or execution efficiency, ensuring that specified performance levels are met. These constraints guide how systems or projects operate, like establishing timing budgets for high-speed chip design or managing bottlenecks in manufacturing processes to achieve desired outcomes and optimize overall throughput.
Performance criteria – These are specific, measurable standards or benchmarks used to evaluate the effectiveness, success, or quality of an individual, project, or organization’s performance. They act as clear expectations and define what is needed to achieve success, aligning efforts with goals and allowing for progress tracking and identification of areas for improvement. Examples are productivity, quality of work, timeliness, customer satisfaction, or financial targets like revenue growth and cost reduction.
Performance guarantee test – It is a process to verify that a product, service, or system meets the performance criteria specified in a contract or agreement. It ensures the item in question performs as promised by the provider and that the agreed-upon standards are met. If the performance falls short, the provider is typically obligated to take corrective actions.
Performance indices – These indices are derived based on the trade-off between a constraint and the free variable; they characterize the performance of a particular geometry as a function of material properties. Each combination of function, objective and constraint leads to a particular performance index defined by a material property or a combination of material properties.
Performance management – It includes activities in the organization which ensure that goals are consistently being met in an effective and efficient manner. It focuses on the performance of the organization, department, employees, or even the production processes which produces the product or service, as well as many other areas. It is also known as a process by which the organization aligns the resources, systems and employees to strategic objectives and priorities. An organization aspiring for success needs in place the process of performance management. Aims of the performance management in the organization are (i) to make the performance of the organization visible, (ii) to drive the management and the employees to take actions, and (iii) to provide timely feedback on the effect of the actions for taking corrective measures.
Performance measure – It is a qualitative or quantitative measure of an outcome, intended to gauge the performance of the organization, its initiatives, policies, and / or activities. A performance measure tracks the degree to which the organization’s performance can influence change (i.e., the progress towards a target).
Performance monitoring – It is the systematic process of collecting and analyzing data to evaluate how well a system, process, or individual is performing against predefined objectives and standards. It involves tracking key metrics, identifying issues and bottlenecks, making informed decisions, and implementing improvements to enhance efficiency, achieve goals, and ensure desired outcomes. This practice is applied in different fields, from production processes and applications to employee productivity.
Performance parameters – These are measurable criteria which define and evaluate the effectiveness, efficiency, and overall quality of a system, process, or product. They provide objective ways to understand how well something is functioning, with examples including accuracy, speed, reliability, resource utilization, and output metrics.
Performance rating scale – It is a tool which evaluates the job performance of the employees. It is a systematic way to assess how well an employee is meeting their job responsibilities.
Performance standards – These are standards which state design requirements but not the methods that are to be used to achieve the objective.
Performance testing – It is defined as the process of evaluating a system’s or application’s ability to perform its designated functions efficiently and reliably under different load conditions. This type of testing focuses on non-functional characteristics such as speed, responsiveness, scalability, stability, and resource utilization.
Perform maintenance – It is to undertake planned actions—including inspection, cleaning, lubrication, adjustment, and part replacement—to keep equipment, machinery, and systems in optimal operating condition, thereby preventing breakdowns, maximizing lifespan, and ensuring reliable, uninterrupted service. It is a crucial discipline aimed at optimizing equipment reliability, availability, and maintainability through systematic engineering principles and processes.
Periclase – It is a magnesium mineral which occurs naturally in contact metamorphic rocks and is a major component of most basic refractory bricks. It is a cubic form of magnesium oxide (MgO). In nature it normally forms a solid solution with wustite (FeO) and is then referred to as ferro-periclase or magnesio-wustite.
Periclase grain – It is a crystalline magnesium oxide in granular form. It contains at least 85 % by weight magnesia.
Perimeter – It is the length of a closed boundary which encompasses, surrounds, or outlines either a two-dimensional shape or a one-dimensional line. The perimeter of a circle or an ellipse is called its circumference. Calculating the perimeter has several practical applications. A calculated perimeter is the length of fence needed to surround a yard. The perimeter of a wheel / circle (its circumference) describes how far it will roll in one revolution.
Period – It is a horizontal row of the periodic table of the elements and the elements which share it.
Periodic reverse plating – It is a method of plating in which the current is reversed periodically. The cycles are normally no longer than a few minutes and may be much less.
Periodic table of the elements – It is also simply known as the periodic table. It is a tabular arrangement of the chemical elements organized by their atomic number, electron configuration, and other chemical properties, whose adopted structure shows periodic trends and is used by people to derive relationships between different elements as well as to predict the properties and behaviours of undiscovered or newly synthesized elements. In the periodic table of the elements, the horizontal rows are called periods and the vertical columns are called groups or families.
Peripheral – It is an external device that connects to a computer or system to expand its capabilities, such as input / output or storage, without being part of the core functional components. While not essential for a computer’s basic operation, peripherals enhance user interaction and functionality, including examples like keyboards, mice, printers, scanners, and external storage devices.
Peripheral activity – It is one which is not essential or central to an organization’s main function or goals, but rather, it exists on the periphery, frequently supporting or related to core activities. It is something which is considered less important or significant compared to the main or core activities of an organization.
Peripheral coarse grain, peripheral grain band – It is an effect shown in extruded products and also forgings made from extruded stock. It is an area of recrystallized grains at the periphery which has lower properties than the non-recrystallized core.
Peripheral discharge – In grinding mills, it refers to a discharge method where the ground material exits the mill through openings around the circumference of the mill’s shell, rather than through the trunnion (the hollow shaft at the end of the mill). This method is particularly useful for dry grinding and when minimizing fines is desired, allowing for a quick passage of material through the mill.
Peripheral discharge grinding mill – It discharges ground product through openings in the side (periphery) of the mill shell, rather than through the end trunnion like traditional overflow mills. This design is desired for applications needing a free, gravity-assisted discharge and is particularly useful in dry grinding or when high percent of fines are detrimental. By using bushings with desired hole sizes and external flanges to attach a stationary hopper, the peripheral discharge prevents pulp splash or excessive dust.
Peripheral milling – It consists of milling a surface parallel to the axis of the cutter.
Peripheral segregation – It is a casting defect which is normally found in the peripheral zone of the casting. It is characterized by an above-average high concentration of alloying elements and a sharp concentration jump to the adjacent structure. There are also frequently alloying element impoverished zones below the peripheral segregation zones. The occurrence of peripheral segregations has to be considered in relationship to the solidification of the peripheral shell. Peripheral segregation forms during the dwell of the peripheral shell in the air gap region. Transport of residual melt regions enriched in the alloying elements towards the surface of the cast log takes place. The main transport mechanism is the metallo-static pressure of the melt before the peripheral shell. This is referred to as air gap segregation. A further mechanism for the formation of peripheral segregation is the residual melt enriched with alloying elements overflowing the meniscus curvature of the peripheral shell. This is referred to as meniscus segregation. Different segregation formation shapes can be differentiated in peripheral segregation.
Peripheral speed – It is the linear speed of a point on the outer edge or circumference of a rotating object, calculated by multiplying its circumference by its rotational speed. It is measured in units of distance per time, such as meters per second. Peripheral speed differs from rotational speed (revolutions per minute) and is an important factor in processes like atomization, milling, and fluid machinery, where it impacts performance, safety, and material interaction.
Peripheral velocity – It refers to the velocity of a point located on the outer edge of a rotating circle or disc. It is the speed at which the outermost point of the object moves in a circular path.
Periphery – It is a boundary or outer part of any space or body. It means a circumference or outer surface.
Perishable – It refers to goods which have a limited shelf life and can spoil or decay quickly if not stored properly. These products need specific handling and transportation methods to maintain their freshness, often involving temperature control or refrigeration.
Perishable goods – It means goods which rapidly decay because of their natural characteristics, in particular in the absence of appropriate storage conditions.
Perishable tooling – It refers to tools used in manufacturing processes which are designed to wear out or break down over time due to repeated use or exposure to demanding conditions. These tools are typically designed to be replaced rather than repaired or refurbished after a certain period of use.
Peristaltic motion – It is a fluid transport mechanism which uses progressive waves of contraction and relaxation in a flexible tube or channel to move fluids or solids. This technique uses external forces, such as rotating rollers or external pressures, to generate these waves, which then create localized regions of higher pressure to propel the fluid forward, making it particularly useful for applications involving shear-sensitive, viscous, or sterile fluids.
Peristaltic pump It is also normally known as a roller pump. It is a type of positive displacement pump used for pumping a variety of fluids. The fluid is contained in a flexible tube fitted inside a circular pump casing. Majority of the peristaltic pumps work through rotary motion, though linear peristaltic pumps have also been made. The rotor has a number of ‘wipers’ or ‘rollers’ attached to its external circumference, which compress the flexible tube as they rotate by. The part of the tube under compression is closed, forcing the fluid to move through the tube.
Peritectic – It is an isothermal reversible reaction in metals in which a liquid phase reacts with a solid phase to produce a single (and different) solid phase on cooling.
Peritectic equilibrium – It is a reversible univariant transformation in which a solid phase stable only at lower temperature decomposes into a liquid and a solid phase that are conjugate at higher temperature, or conversely.
Peritectic point – It is the point on a phase diagram where a reaction takes place between a previously precipitated phase and the liquid to produce a new solid phase. When this point is reached, the temperature remains constant until the reaction has run to completion. A peritectic point is also an invariant point.
Peritectic reaction – It is a phase transformation where a liquid phase and a main solid phase react at a constant temperature to form a new, secondary solid phase, frequently with a different crystal structure. This reaction is represented on a phase diagram by the equation Liquid + Solid A = Solid B. It is important in the processing of alloys, like iron-carbon and copper-zinc, for controlling their micro-structure, properties, and the development of specific alloy phases such as austenite and dela-ferrite.
Peritectic temperature – It is the specific temperature at which a peritectic reaction occurs, where a solid phase reacts with a liquid phase to form a new, different solid phase upon cooling. This transformation is important for understanding and controlling the micro-structural development and mechanical properties of alloys during processes like casting and heat treatment, as it represents a point of phase equilibrium and stability.
Peritectoid – It is an isothermal reversible reaction in which a solid phase reacts with a second solid phase to produce a single (and different) solid phase on cooling.
Peritectoid equilibrium – It is a reversible univariant transformation in which a solid phase stable only at low temperature decomposes with rising temperature into two or more conjugate solid phases.
Peritectoid point – It is similar in appearance to a peritectic, being an inverted ‘V’ corresponding to an upper limit of formation of a single solid phase. But the difference is that the two-phase field above is formed of two solid phases (whereas in a peritectic, one is liquid).
Perlite – It is a highly siliceous volcanic rock which can be expended by heating into a porous mass of particles. Perlite can be used as an insulation in foundry sand mixtures. It is not to be confused with pearlite.
Permafrost – It is the ground (soil or rock and included ice and organic material) which remains at or below 0 deg C for at least 2 consecutive years.
Permanence – It is the property of a plastic which describes its resistance to appreciable changes in characteristics with time and environment.
Permanent – It refers to a state, structure, or characteristic which is designed to be lasting, enduring, and unchanging, maintaining its form, function, and integrity over a long period or indefinitely, contrasting with temporary elements. Examples include permanent structures like bridges, permanent loads (dead loads) such as a building’s weight, and permanent joints like welded connections.
Permanent deformation – It is the irreversible change in an object’s shape or size which remains after the applied forces are removed, also known as plastic deformation. This occurs when the forces exceed a material’s yield strength, causing its internal structure to rearrange and its bonds to break and reform, resulting in a lasting alteration to its geometry.
Permanent dipole – It refers to a molecule with a fixed, inherent separation of positive and negative charges, resulting in a constant electric dipole moment. This permanent polarity arises from a substantial difference in electro-negativity between covalently bonded atoms or an uneven distribution of lone pairs of electrons within the molecule’s structure, making one end partially positive (delta+) and the other partially negative (delta-). These dipoles interact through the strongest van der Waals forces, known as Keesom forces. Molecules possessing a permanent dipole are known as polar molecules and are important in several applications, such as acting as dielectric materials in capacitors and influencing chemical and physical properties like solubility and inter-molecular forces.
Permanent elongation – It is also known as plastic elongation or deformation. It refers to the irreversible lengthening of a material after it has been subjected to a force beyond its elastic limit. When a material is stretched, it initially deforms elastically, returning to its original shape when the force is removed. However, if the force exceeds a certain threshold (the yield strength), the material undergoes plastic deformation, resulting in a permanent change in its length.
Permanent hardness – It is non-carbonate hardness. It is because of the presence of dissolved chlorides, sulphates, and nitrates of calcium and magnesium. Unlike temporary hardness, permanent hardness is not destroyed on boiling. It is removed by special methods. it can be removed by the use of chemical agents.
Permanent joint – It is a connection between components which cannot be disassembled without causing damage or destruction to the joint elements or the parts themselves. These joints are designed to be fixed and lasting, offering high strength, structural integrity, and frequently a leak-proof connection, though they sacrifice ease of disassembly for maintenance or repair. Examples of permanent joints include welded joints, riveted joints, and glued joints.
Permanent linear change (PLC) – It consists of dimensional expansion or contraction which remains in a refractory which is heated with no externally applied force to a specified temperature for a specified time and then cooled to ambient temperature.
Permanent magnet – It is an object made from a material which is magnetized and which creates its own persistent magnetic field. It is a magnet which retains its polarization after an external field is removed.
Permanent magnet material – It is a ferro-magnetic metal or alloy capable of being magnetized permanently because of its ability to retain induced magnetization and magnetic poles after removal of externally applied fields, i.e., a metal or alloy with high coercive force. The name is based on the fact that the quality of the early permanent magnets has been related to their hardness. The ferro-magnetic metal or alloy include the elements iron, nickel and cobalt and their alloys, some alloys of rare-earth metals, and some naturally occurring minerals such as lodestone. Although ferro-magnetic materials are the only ones attracted to a magnet strongly enough to be normally considered magnetic, all other substances respond weakly to a magnetic field, by one of several other types of magnetism.
Permanent magnet (PM) motor – It is an electric motor which uses permanent magnets to create a magnetic field, rather than electro-magnets, to generate rotational mechanical force. This design results in high efficiency, good power density, and a compact size, making them suitable for applications such as robotics, electric vehicles, and various automation systems. Permanent magnet motors can be either direct current (DC) or alternating current (AC) synchronous motors, with the key differentiator being the use of permanent magnets for the stationary or rotating magnetic field.
Permanent magnet synchronous generator – It is an alternating current generator which uses a permanent field magnet instead of an electro-magnet.
Permanent magnet synchronous motor (PMSM) – It is an alternating current electric motor which uses permanent magnets on its rotor to create a rotating magnetic field, which the stator’s rotating field then locks onto. Operating at a constant synchronous speed, the permanent magnet synchronous motor offers high efficiency, high power density, and high torque, making it ideal for applications from appliances to robotics and electric vehicles. Key components include a stator with windings and a rotor with permanent magnets, eliminating the need for a field winding and direct current supply on the rotor, which simplifies construction and reduces rotor current losses.
Permanent mould – It is a metal, graphite, or ceramic mould (other than an ingot mould) of two or more parts which is used repeatedly for the production of several castings of the same form. Liquid metal is normally poured in by gravity.
Permanent mould casting – Here, the two halves of the mould are made of metal, normally cast iron, steel, or refractory alloys. The cavity, including the runners and gating system are machined into the mould halves. For hollow parts, either permanent cores (made of metal) or sand-bonded ones can be used, depending on whether the core can be extracted from the part without damage after casting. The surface of the mould is coated with clay or other hard refractory material. This improves the life of the mould. Before moulding, the surface is covered with a spray of graphite or silica, which acts as a lubricant. This has two purposes namely (i) it improves the flow of the liquid metal, and (ii) it allows the cast part to be withdrawn from the mould more easily. The process can be automated, and hence yields high through-put rates. Also, it produces very good tolerance and surface finish. It is normally used for producing pistons used in car engines, gear blanks, cylinder heads, and other parts made of low melting point metals, e.g., copper, bronze, aluminum, and magnesium etc.
Permanent set – It is the deformation remaining after a sample has been stressed a prescribed quantity in tension, compression, or shear for a specified time period and released for a specified time period. For creep tests, it is the residual unrecoverable deformation after the load causing the creep has been removed for a substantial and specified period of time. It is also the increase in length, expressed as a percentage of the original length, by which an elastic material fails to return to its original length after being stressed for a standard period of time.
Permeable medium – It is a porous material, such as soil or a rock formation, which allows fluids (liquids or gases) to flow through its interconnected pore spaces. The permeability of the medium is a measure of its ability to transmit fluids, a property that depends on the size, shape, and connectivity of these pore spaces. This concept is crucial in fields like civil engineering for assessing ground conditions.
Permeable structure – It allows fluids (like water or air) to flow through its porous solid matrix, enabling analysis of flow within media such as soils, porous dams, or permeable pavements. These structures frequently feature a network of interconnected voids or pores within the solid material, facilitating passage of liquids or gases while potentially trapping sediments or managing storm-water.
Permeable surface – It is a material or ground-cover which allows water to pass through it, rather than runoff over it, enabling stormwater to infiltrate into the underlying layers of soil and aggregate. These surfaces, such as permeable concrete, porous asphalt, or interlocking pavers, are designed to manage water by reducing urban runoff, preventing flooding, improving water quality by filtering pollutants, and recharging the groundwater table.
Permeability – It is the passage or diffusion (or rate of passage) of a gas, vapour, liquid, or solid through a material (frequently porous) without physically or chemically affecting it, i.e., the measure of fluid flow (gas or liquid) through a material. It is also a general term used to express different relationships between magnetic induction and magnetizing force. These relationships are either ‘absolute permeability’, which is a change in magnetic induction divided by the corresponding change in the magnetizing, or ‘specific (relative) permeability’, which is the ratio of the absolute permeability to the permeability of free space. In metal casting, it is the characteristics of moulding materials which permit gases to pass through them. In case of refractories, it is the capacity of a refractory for transmitting a fluid (gas or liquid)’ ‘Permeability number’ is determined by a standard test.
Permeability coefficient – It is the steady-state rate of flow of gas through unit area and thickness of a solid barrier per unit pressure differential at a given temperature.
Permeable surface – It is the surface which allow rain water to soak into the surface. The water is stored temporarily under the surface in the sub-base layer which is located below the surfacing (a storage layer). It is then allowed to slowly seep into the ground, or if the ground is unsuitable for this it flows to the drains. Even when connected to the drains, the permeable surfaces act as a buffer to slow the rate of water flow and reduce the volume of water entering the drainage system. Permeable surfaces reduce the total volume, the frequency, and the peak flow rate of rainwater which enters drains and water courses. Hence, they can help to reduce the impact of rainfall on the drainage system. If sufficient area is covered by permeable surfaces it can help to reduce the risk of flooding from sewers and water courses.
Permian rock – It refers to sedimentary and sometimes igneous rocks formed during the Permian Period (roughly 299 million years to 251 million years ago), known for geological properties important for to resource development and construction. These formations, which include siliciclastics, carbonates, and siliceous rocks. These are analyzed for their aggregate properties (strength, durability).
Permissible error – It is the maximum quantity by which a measurement or calculation is allowed to deviate from its true or accepted value to ensure it remains within acceptable standards and meets the needed accuracy for a specific application or instrument. It serves as a critical threshold to maintain the trustworthiness and functionality of measurements, calculations, and manufactured parts within a given process or regulation.
Permissible pressure – It is normally referred to as ‘maximum allowable working pressure’ (MAWP), which is the highest pressure a component or vessel can safely withstand in its normal operating position at a specific temperature. It is a critical safety value, normally calculated based on the weakest part of the structure, and is used to prevent failures by defining the upper limit for system operation.
Permissible range – It is also known as tolerance. It is the acceptable limit of variation for a dimension, property, or parameter of a product or system, which allows it to function as intended without compromising its quality or safety. This range is defined by upper and lower limits, and any measurement outside these limits is considered out of tolerance. Tolerances are crucial for ensuring parts fit together, systems operate correctly, and manufacturing processes are consistent.
Permissible stress design – It is a design philosophy used by engineers. The designer ensures which the stresses developed in a structure because of the service loads do not exceed the elastic limit. This limit is normally determined by ensuring that stresses remain within the limits through the use of factors of safety. In structural engineering, the permissible stress design approach has normally been replaced internationally by limit state design (also known as ultimate stress design) as far as structural engineering is considered, except for some isolated cases.
Permissible variation – For testing machines, it is the maximum allowable error in the value of the quantity indicated. It is convenient to express permissible variation in terms of the percent error.
Permit – It is an authorization, license, or equivalent control document issued by a regulatory authority to implement the requirements of a regulation or to operate a facility. For example, in case of environment regulation, it is normally to limit the quantity of pollutants discharged into the environment. Other example is permit to operate a wastewater treatment plant.
Permit to work – It is a formal written or verbal authority to operate a planned procedure, which is designed to protect personnel, working in hazardous areas or activities, or when performing maintenance on a safety-related system. It is authority for a safe system of work.
Perm-selective membranes – These are defined as specialized membranes which selectively allow the passage of specific gases, such as hydrogen, while blocking others. They can be composed of different materials, including dense metallic, polymeric, ceramic, and porous carbon membranes, with metallic membranes, particularly palladium-based alloys, being noted for their high selectivity and ability to produce ultra-pure hydrogen.
Perm selectivity – It is the preferential permeation of certain ionic species through ion-exchange membranes, influenced by factors such as charge, individual mobility, and the presence of solvated protons in different cell configurations. In the absence of a liquid electrolyte, the perm-selectivity of the membrane can be considered unity.
Permutation – It is the arrangement of a set of objects or elements in a specific order, where the order of selection matters and different sequences lead to different outcomes. Permutations are used to determine the total number of configurations or possible orderings of elements, which helps in solving problems related to scheduling, coding, and data structures in different engineering fields.
Permutit process – It is also known as the zeolite process. It is an ion-exchange method in chemical engineering which softens hard water by exchanging calcium (Ca2+) and magnesium (Mg2+) ions for sodium (Na+) ions using sodium permutit (sodium zeolite). This process uses a bed of permutit material to filter hard water, capturing the hardness-causing ions and releasing sodium ions into the water, which then becomes soft. After the permutit becomes saturated, it can be regenerated with a concentrated brine (NaCl) solution to restore its sodium content for continued use.
Perot Interferometer – It is also called Fabry-Perot interferometer (FPI). It is an optical device consisting of two parallel, partially reflective mirrors that form a resonant cavity. Light reflects multiple times within this cavity, creating interference patterns that can precisely measure changes in the optical path length within the cavity. This sensitivity makes it highly valuable in engineering for applications such as strain, pressure, temperature, and gas concentration sensors, particularly in geotechnical monitoring and remote sensing.
Perovskite – It is a class of materials which share the same crystal structure as the mineral calcium titanate (CaTiO3), which is also called perovskite, and has the general chemical formula ABX3. These materials can be designed with a wide range of physical properties by varying the chemical elements in the ‘A’, ‘B’, and ‘X’ positions, making them useful for applications in solar cells, fuel cells, memory devices, and LED (light-emitting diode) screens.
Perovskite solar cells – These are thin-film solar cells composed of multiple layers of materials applied to a substrate, achieving efficiencies exceeding 25 % in laboratory settings. These solar cells are hetero-junction solar cells which utilize organometal trihalide perovskite materials (CH3NH3PbX3, where X = I, Br, Cl) sandwiched between an electron transporting layer and a hole transporting layer, configured in either n-i-p or p-i-n structures.
Peroxide – It is a class of compounds which contain a peroxy group, having the generic structural formula R–O–O–R, where ‘R’ is any element or functional group, e.g., hydrogen peroxide (empirically H2O2, structurally H–O–O–H). It is another name for the peroxy group itself. It is also a salt of the anion (O2)2-.
Peroxy – It is also known as peroxide and sometimes peroxo. It is a functional group consisting of two oxygen atoms directly connected to each other by a single bond and each also connected to one other atom. Peroxides have the general structural formula –O–O–.
Peroxyacetyl nitrate (PAN) – It is a secondary pollutant present in photochemical smog. It is thermally unstable and decomposes into peroxyethanoyl radicals and nitrogen di-oxide gas. It is an oxidant which is more stable than ozone. Hence, it is more capable of long-range transport than ozone. It serves as a carrier for oxides of nitrogen (NOx) and causes ozone formation in the global troposphere. It is a toxic air pollutant which can cause eye irritation, lung damage, and genetic damage. It is also considered a potential contributor to skin cancer.
Peroxy acid – It is a type of chemical compound known as an acid that contains a functional group with two adjacent oxygen atoms, specifically the perhydroxyl group (-OOH), which includes a peroxy bond (-O-O-). These compounds act as strong oxidizing agents and are sometimes called peracids. Examples of peroxy acids include peracetic acid and peroxy-mono-sulphuric acid.
Perpendicular anisotropy (PA) – It is frequently seen as ‘perpendicular magnetic anisotropy’ (PMA). It is a property of magnetic thin films where the preferred direction of magnetization aligns perpendicular (out-of-plane) to the film’s surface, rather than within the plane of the film. This orientation is driven by factors like interfacial effects and spin-orbit coupling, which can overcome the demagnetization energy which normally favours in-plane magnetization, leading to a stable, out-of-plane magnetic state.
Perpendicular section – It is a section cut perpendicular to a surface of interest in a sample.
Perseveration – It is defined as the tendency to continue a particular behaviour, even when it ceases to be effective or rewarding.
Persistence – It is defined as the ability to keep going with a behaviour to reach a goal, even when the task is difficult or takes a long time.
Persistent organic pollutants (POPs) – These are organic compounds which are resistant to degradation through chemical, biological, and photolytic processes. These pollutants are toxic and adversely affect human health and the environment. Since these pollutants can be transported by wind and water, majority of these pollutants generated at one place can and do affect people and wild-life far from where they are used and released.
Persistent slip lines – These are small steps contained within a grain and visible at the microscale on free surfaces or in metallographic cross sections of parts which have been subject to a number of cyclic loads slightly below the number needed to initiate a crack. The precursor to a fatigue crack.
Personal area networks (PANs) – They are defined as short-range wireless networks which interconnect two or more devices, typically within a distance of around 10 meters, and are frequently set up temporarily for specific purposes. An example of a personal area network is the connection between a cell phone and a Bluetooth headset.
Personal computer (PC) – It is a computer designed for individual use. It is typically used for tasks such as word processing, internet browsing, email, multimedia playback, and gaming. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or technician.
Personal protective equipment (PPE) – It is the equipment or a device which is intended to be worn or otherwise used by an employee at work and which protects the employee against one or more risks arising from the operation to the employee’s safety or health. It includes any addition or accessory to the equipment designed to meet a similar objective. It protects the employee from hazards and any harmful conditions (existing and potential) which can result in injury, illness, or possibly fatal injury. PPE can be an item worn on the body, such as gloves, or a device, such as a protective shield or barrier. Besides face shields, safety glasses, helmets, and safety shoes, personal protective equipment also includes a variety of devices and garments such as goggles, coveralls, gloves, vests, earplugs, and respirators.
Person-period data format – It is a type of dataset for statistical analysis in which each subject contributes to the dataset as many records as there are occasions on which that subject is measured. Datasets in this format are frequently necessary in survival analysis and growth-curve analysis.
Personnel – These are a group of people who are employed in an organization or engaged in an organized undertaking.
Personnel training – It is the process of teaching employees the knowledge and skills they need to perform their jobs. It can also refer to the ongoing process of improving their skills and competencies.
Perspective drawing – A perspective drawing highlights the spatial aspects of a building along with showing its three-dimensional volumes. It is the realistic image of the project which is under construction. In addition to this, there are different types of perspectives based on vanishing points. Perspective drawing is a technique for depicting three-dimensional volumes and spatial relationships based on the eye level and vanishing point (or points) of the viewer. It can give a realistic impression of what a volume or space is going to look like in reality. Constructing perspective drawings of projects is extremely complicated, but has been much simplified recently because of the development of computer aided design (CAD), building information modelling (BIM), and other forms of computer-generated imagery (CGI).
Pervaporation (PV) – It is defined as an emerging membrane desalination technology that utilizes thermal energy and phase change processes to efficiently produce drinking water, offering high salt rejection and the potential for waste heat reuse.
Pervaporation membrane reactor (PVMR) – It is a hybrid system which combines a chemical reaction with a pervaporation separation process within a single unit. In this reactor, a membrane selectively removes one or more products or byproducts from the reaction mixture as a vapour, which drives the reaction forward by overcoming thermodynamic equilibrium limitations. This integrated approach offers advantages such as increased conversion rates and improved operational performance, making it a promising technology for several chemical processes.
Pervious concrete – It is also known as porous or permeable concrete. It is a special, high-porosity concrete with a highly interconnected void structure which allows water to pass directly through it, reducing stormwater runoff and recharging groundwater. It is composed of cement, coarse aggregates, and a minimal quantity of water, with little to no fine aggregate (sand), to maintain the void interconnectivity needed required for water flow.
Pessimistic scenario – It refers to a theoretical situation which represents the worst-case outcome in scenario analysis, used to forecast the performance of a system under adverse conditions and assess potential impacts on system parameters.
Pessimistic time – It is the time needed to complete an activity under the most unfavourable conditions.
PEST analysis – PEST (political, economic, social and technological) analysis is a framework of external macro-environmental factors which are used in strategic management and market research. This analysis is an environmental scanning framework for organizations to understand the external conditions and 0perations of the organization in order to assist managers in strategic planning. It has also been termed ETPS analysis. PEST analyses give an overview of the different macro-environmental factors to be considered by the organization, indicating market growth or decline, organizational position, as well as the potential of and direction for operations.
PESTLE analysis – It is a framework used to assess the macro-environmental factors which can affect an organization. It stands for Political, Economic, Social, Technological, Legal and Environmental factors. By analyzing these external factors, organizations can identify opportunities and threats, helping them make informed strategic decisions. Political factor includes government policies, regulations, and political stability which can impact an organization. Economic factor considers economic growth, inflation, interest rates, and other economic indicators which affect the organizational operations. Social factor involves analyzing social trends, demographics, cultural norms, and consumer behaviour. Technological factor looks at technological advancements, innovation, and the adoption of new technologies which can impact an organization. Environmental factor examines the impact of environmental regulations, sustainability concerns, and natural resources on the organizational practices. Legal factor considers the legal framework, including laws and regulations which govern the organizational operations.
Pesticide – It is a chemical compound which is used to control unwanted species which attack crops, animals, or people. This diverse group of chemicals includes herbicides, fungicides, and insecticides.
Petch effect – It is also known as the Hall–Petch effect. It is the observation that a material’s strength (specifically, its yield strength) increases as its grain size decreases. This is since smaller grains mean a higher proportion of grain boundaries, which act as barriers to dislocation movement, needing more stress to initiate plastic deformation. Beyond a certain critical grain size, this relationship can reverse, leading to a decrease in strength as grains become so small they can move readily with each other, a phenomenon known as the inverse Hall–Petch effect.
Petrochemical fuels – These are liquid hydrocarbon fuels directly derived from petroleum which are used for powering transportation and industry. While the term ‘petrochemical’ technically refers to chemicals made from petroleum and natural gas, ‘petrochemical fuels’ specifically denotes those refined fractions of crude oil used for fuel, differentiating them from the wide array of petrochemical products like plastics, fertilizers, and solvents which are also made from these same raw materials.
Petrography – It is a branch of petrology which focuses on detailed descriptions of rocks. Someone who studies petrography is called a petrographer. The mineral content and the textural relationships within the rock are described in detail. The classification of rocks is based on the information acquired during the petrographic analysis. Petrographic descriptions start with the field notes at the outcrop and include macroscopic description of hand-sized specimens. The most important petrographer’s tool is the petrographic microscope. The detailed analysis of minerals by optical mineralogy in thin section and the micro-texture and structure are critical to understanding the origin of the rock.
Petrographic analysis – It is the microscopic study of rocks, coal, and even ceramics or concrete to determine their composition, texture, and microstructural features, using a polarizing microscope on thin sections. This analysis helps to understand the origin of a rock, predict its mechanical behaviour and durability in construction, characterize materials like coal for resource potential.
Petroleum – It is also called crude oil. It is a naturally occurring liquid found beneath the earth’s surface which can be refined into fuel. A fossil fuel, petroleum is created by the decomposition of organic matter over time and used as fuel in furnaces and to power vehicles, heating units, and machines, and can be converted into plastics.
Petroleum-based metal working lubricants -This family of metal working lubricants provides the users with broadest range of choices of various lubricant properties both chemical and physical in nature. The primary vehicle in the make-up of this family of lubricants is the blending oil (which can be of varying viscosities). For obtaining additional physical properties additives such as fats, polymers, and wetting agents can also be added. If necessary, chemical extreme pressure agents such as sulphur, chlorine, and phosphorous can be added to the formulation. In special cases, additives can be added for the rust prevention. Also, cleaning inducers can be included to provide for easier cleaning. Petroleum-based lubricants are used in metal working processes on a selective basis. Cosmetic-type piece parts of stainless steel and some heavy-duty formed sections can require petroleum-based lubricants.
Petroleum coke – It is also called pet coke. Itis a final carbon-rich solid material which is derived from oil refining, and is one type of the group of fuels referred to as cokes. Pet coke is the coke which, in particular, derives from a final cracking process, a thermo-based chemical engineering process which splits long chain hydro-carbons of petroleum into shorter chains. The process takes place in units termed coker units. Other types of coke are derived from coal. Stated briefly, petroleum coke is the carbonization product of high-boiling hydro-carbon fractions obtained in petroleum processing (heavy residues.
Petroleum-coke-base carbon refractory – It is a manufactured refractory comprised substantially of calcined petroleum coke.
Petroleum engineering – It is a field of engineering which is concerned with the activities related to the production of hydrocarbons, which can be either crude oil or natural gas. Exploration and production are deemed to fall within the upstream sector of the oil and gas industry. Exploration, by earth scientists, and petroleum engineering are the oil and gas industry’s two main subsurface disciplines, which focus on maximizing economic recovery of hydrocarbons from subsurface reservoirs. Petroleum geology and geophysics focus on provision of a static description of the hydrocarbon reservoir rock, while petroleum engineering focuses on estimation of the recoverable volume of this resource using a detailed understanding of the physical behaviour of oil, water and gas within porous rock at very high pressure.
Petroleum oil – It is a refined hydro-carbon oil without animal or vegetable additives.
Petroff equation – It is an equation describing the viscous power loss in a concentric bearing full of lubricant. The resisting torque on the shaft (To = shear stress × shaft radius × bearing area) is given by ‘To = (pi square x n x N x L x D square)/2c’ where pi = 3.1416, ‘n’ is the dynamic viscosity, ‘N’ is the shaft speed, ‘L’ is the bearing length, ‘D’ is the shaft diameter, and ‘2c’ is the diametral clearance.
Pewter – It is a tin-base white metal containing antimony and copper. Originally, pewter has been defined as an alloy of tin and lead, but to avoid toxicity and dullness of finish, lead is excluded from modern pewter. These modern compositions contain 1 % to 8 % antimony and 0.25 % to 3 % copper.
PFD – it is ‘Probability of Failure on Demand’ which is applied normally to a plant protection system.
pH – It is the hydrogen ion concentration of a water to denote acidity or alkalinity. This pH number is the negative exponent of 10 representing hydrogen ion concentration in grams per litre. For example, a pH of 7 represent (10)-7 grams per litre. It is the negative logarithm of the hydrogen-ion activity. It denotes the degree of acidity or basicity of a solution. At 25 deg C, a pH of 7 is the neutral value. Decreasing values below 7 indicates increasing acidity, while increasing values above 7 indicates increasing basicity. The pH values range from 0 to 14.
Phaneritic – It is a term used to describe the coarse-grained texture of some igneous rocks.
PHAR (Pickliq hydrochloric acid regeneration) – It is a process for regeneration of spent hydrochloric acid from steel pickling. The process is applicable to any size pickling operation. PHAR technology eliminates the disposal problem, creating considerable reductions in operating, environmental, and capital costs. The process uses sulphuric acid to restore hydrochloric acid for reuse. PHAR produces ferrous sulphate crystals (sulphate hepta-hydrate), an economically viable by-product, which can be sold for the industrial purposes. By eliminating transportation and / or treatment of spent pickling liquor, along with costs associated with generating hydrochloric acid to replace the spent liquor solution, PHAR produces energy savings of 95 %, cost savings of 52 %, and a 91 % reduction in CO2 emissions, compared to the existing technology.
Phase – It is a physically homogeneous and distinct portion of a material system. It is a region of material which is chemically uniform, physically distinct, and (frequently) mechanically separable. In a system consisting of ice and water in a glass jar, the ice cubes are one phase, the water is a second phase, and the humid air is a third phase over the ice and water. The glass of the jar is a different material, in its own separate phase. More precisely, a phase is a region of space (a thermodynamic system), throughout which all physical properties of a material are essentially uniform. Examples of physical properties include density, refraction index, magnetization, and chemical composition. In electricity, phase refers to the distribution of alternating current electric power. It describes the position of a point in time on a wave-form cycle. It is defined by the electric load distribution corresponding to the type of unit, which could be a single-phase or a three-phase electrical system. Single-phase has less power, requiring two wires, whereas three-phase (3-phase) requires more, such as three or four.
Phase change – It is the transition from one physical state to another, such as gas to liquid, liquid to solid, gas to solid, or vice versa. It is defined as a change in the arrangement of atoms, molecules, or particles of a substance with a fixed chemical composition, induced from the outside, resulting in the presence of new properties of matter. This physical phenomenon is reversible and manifests through the emergence of distinct material properties
Phase change / bi-state sensors – These low-cost non-electric sensors are made from heat-sensitive fusible crystalline solids which change decisively from a solid to a liquid with a different colour at a fixed temperature depending on the blend of ingredients. They are available as crayons, lacquers, pellets, or labels over a wide range of temperatures from 38 deg C to 1,650 deg C. They offer a very inexpensive method for surface temperature visual verification within around 0.5 deg C. Monitoring minimum and maximum temperatures during shipment of perishable goods is a common application.
Phase change lubrication – It is the lubrication provided by steady melting of a lubricating species. It is also known as melt lubrication.
Phase contrast – It is the contrast in high-resolution transmission electron microscopy (TEM) images arising from interference effects between the transmitted beam and one or more diffracted beams.
Phase contrast illumination – It is a special method of controlled illumination ideally suited to observing thin, transparent objects whose structural details vary only slightly in thickness or refractive index. This can also be applied to the examination of opaque materials to determine surface elevation changes.
Phase converter – It is an electrical apparatus which converts power from a system of phases to another system, for example, converting single-phase power to three-phase.
Phase diagram – It is a graphical representation of the temperature and composition limits of phase fields in an alloy or ceramic system as they actually exist under the specific conditions of heating or cooling. A phase diagram can be an equilibrium diagram, an approximation to an equilibrium diagram, or a representation of metastable conditions or phases. It is synonymous with constitution diagram. In a binary system, temperature is normally the ordinate and composition the abscissa. Ternary and more complex systems need several two-dimensional diagrams to show the temperature-composition variables completely. In alloy systems, pressure is normally considered constant, although it can be treated as an additional variable. Phase diagram is a graphical representation of the equilibrium temperatures and the composition limits of phase fields and phase reactions in an alloy system.
Phase fault level – It refers to the maximum current which can flow during a fault condition in a power system, which can vary depending on the type of fault and the sequence impedances involved. It indicates that two-phase to earth and single-phase to earth faults can result in higher fault levels than three-phase symmetrical faults when the zero-sequence impedance is low compared to the positive sequence impedance.
Phase-field model – It is a mathematical model for solving interfacial problems. It has mainly been applied to solidification dynamics, but it has also been applied to other situations such as hydrogen embrittlement. It needs information on the structures and properties of individual structural features in a microstructure as input and predicts the microstructure evolution based on fundamental thermodynamic and kinetic principles.
Phase-fired controllers – It is an alternating current power controller which adjusts the effective value of output by switching on at a variable time phase in the alternating current cycle.
Phase locked loop – It is an oscillator circuit which produces an output signal that is in a fixed timing relation to a reference input.
Phase modulation – It means impressing information on a carrier wave by advancing or delaying the waveform slightly. It is related to frequency modulation.
Phase motor – It is an electric motor that operates on a multi-phase power supply, with the most common types being single-phase and three-phase motors. Three-phase motors are naturally self-starting, using a rotating magnetic field created by the power supply to drive the rotor. Single-phase motors, on the other hand, need an additional starting mechanism, such as a capacitor or auxiliary winding, to create a rotating field because the power supply does not inherently produce one.
Phase noise – It is a term for short-term, random fluctuations in the phase or frequency of a signal over time. It represents a deviation from perfect periodicity in the time domain, appearing as unwanted sidebands or a ‘noise hill’ around a signal’s carrier frequency in the frequency domain. This phenomenon is caused by factors like thermal noise, shot noise, and 1/f noise, and it negatively impacts signal quality by reducing sensitivity, increasing bit errors, and causing spectral regrowth in RF (radio frequency) systems.
Phase reactions – These refer to chemical reactions that typically occur in fluid phases, such as liquid or gas, rather than solid phases, unless insoluble solids are involved. These reactions may require specific conditions, such as temperature and pressure, to maintain the desired phase and maximize efficiency in processes.
Phase rule – It is a general principle governing multi-component, multi-phase systems in thermodynamic equilibrium. For a system without chemical reactions, it relates the number of freely varying intensive properties (F) to the number of components (C), the number of phases (P), and number of ways of performing work on the system (N) i.e., F = N + C – P + 1. F=N+C−P+1Examples of intensive properties which count toward ‘F’ are the temperature and pressure. For simple liquids and gases, pressure-volume work is the only type of work, in which case N = 1. The number of degrees of freedom ‘F’ (also called the variance) is the number of independent intensive properties, i.e., the largest number of thermodynamic parameters such as temperature or pressure that can be varied simultaneously and independently of each other. An example of a one-component system (C = 1) is a pure chemical. A two-component system (C = 2) has two chemically independent components, like a mixture of water and ethanol. Examples of phases which count toward ‘P’ are solids, liquids and gases.
Phase saturation – It describes the point where a substance exists in two or more phases (e.g., liquid and vapour) at a specific temperature and pressure, such that further addition of energy does not change the temperature but causes more phase change.
Phase separation – It is the process where a uniform mixture or single-phase solution spontaneously separates into two or more distinct, non-mixing phases with different compositions, properties, or concentrations.
Phase structure – It describes the physical state and arrangement of matter within a metal or alloy, where a phase is a physically homogeneous region with a distinct chemical composition, atomic bonding, and structure. The properties of a material are determined by the types of phases present, their quantities, and how they are distributed, which can be controlled through composition and processing like heat treatment.
Phase supply – It refers to a method of delivering alternating current (AC) power using multiple conductors, or ‘phases’, with each phase’s voltage wave shifted in time by a specific electrical angle from the others. A single-phase supply uses one conductor and a neutral, suitable for residential loads, while a three-phase supply uses three conductors with a 120-degree phase shift, providing more efficient and constant power for industrial use.
Phase titanium alloys – These are defined as titanium alloys which contain both alpha and beta phases, characterized by their distinct crystal structures, which are critical for their mechanical properties and applications, particularly in high-performance components.
Phase transformation kinetics – It is the study of the rates and mechanisms by which one phase of a material changes into another phase. It involves the processes of nucleation (the formation of small particles of the new phase) and growth (the increase in size of these nuclei). These processes are not instantaneous and are influenced by factors like temperature and the required diffusion of atoms, determining how quickly a transformation occurs and the final microstructural outcome.
Phase transformations – These transformations occur through a two-stage process of nucleation and growth, in which nucleation can be spontaneous (homogeneous), or take place on some kind of interface (heterogeneous).
Phase transition – It is a transformation of a chemical substance between solid, liquid, and gaseous states of matter and, in rare cases, plasma. It is also the measurable values of the external conditions at which such a transformation occurs.
Phase transformer – It is a type of transformer classified by the number of phases it operates with, including single-phase, two-phase, three-phase, and even six-phase configurations.
Phase voltage – It is the voltage measured between a single-phase conductor and the neutral point in a polyphase alternating current system. In a star (or Wye) connected system, this is the voltage supplied to an individual load. In a delta connection system, where no neutral exists, the phase voltage is equivalent to the line voltage, or the voltage between any two-phase conductors.
Phasor – It is a vector representing a signal of a given frequency in phase space.
Phasor diagram – It is a graphical representation of a phasor, which is a complex number depicted as a vector in the complex plane, where the vector’s length represents the magnitude and its direction indicates the phase angle.
Phasor measurements – These refer to the implementation of technologies which improve the monitoring of power systems over large geographic areas, facilitating efficient responses to disturbances and preventing cascading blackouts.
Phasor measurement unit – It is a system which measures the timing and amplitude of voltages and currents on an electrical grid, synchronized over a wide geographic area. The resulting measurements can be used to manage power flow on the grid.
pH control – It refers to the process of regulating and stabilizing the hydrogen ion concentration in a solution to maintain a specific pH level, which is a measure of acidity or alkalinity. This is achieved by adding a neutralizing agent, either an acid or a base, to bring the pH within a desired range. pH control is crucial in several applications, including water treatment, and industrial processes, since it impacts chemical reactions, microbial growth, and overall process efficiency.
pH electrode – It is a sensor which measures the acidity or alkalinity of a solution by generating an electrical potential difference across a special glass membrane which is sensitive to hydrogen ions (H+). This potential difference, a measure of hydrogen ion activity, is then read by a pH meter and converted into a pH value, indicating the solution’s acidity (pH lesser than 7) or alkalinity (pH higher than 7).
Phenolic adhesives – These are adhesive materials derived from the reaction of phenol and formaldehyde, which can be formulated as either novolac or resole resins. Novolac phenolic adhesives need an external curative for curing, while resole phenolics can cure themselves and are frequently used in applications such as wood bonding and high-temperature-resistant settings.
Phenolic compounds – These compounds are among the major contaminants of the environment and water sources. Their origin can be from natural or anthropogenic activities.
Phenolic esters cold box systems – Ester-cured phenolic cold box process uses two components namely a resin and a curing agent. The resin (beta-set) is an alkaline phenolic resole in water, and the curing agent is the vapour of a volatile ester, methyl formate. The beta-set resin offers higher strength development and excellent dimensional stability, both highly desirable traits in making high valued castings.
Phenolic resins – Phenolics are thermosetting resins produced by the reaction of phenol or substituted phenol with an aldehyde, normally formaldehyde, in the presence of a catalyst. Phenolic resin composites offer superior fire resistance, excellent high-temperature performance, long-term durability, and resistance to hydro-carbon and chlorinated solvents.
Phenolics – These are organic compounds characterized by one or more hydroxyl (-OH) groups directly bonded to an aromatic ring. They are a diverse group of natural substances, frequently classified as phenolic acids, flavonoids, or tannins. These compounds show important biological activities.
Phenolic urethane cold box systems – The phenolic urethane cold box process utilizes an amine gas to catalyze the reaction between a phenolic resin and an isocyanate resin to produce a urethane bond. Phenolic urethane cold box resins are good for high core strengths, long mixed sand bench life, humidity resistance, and release characteristics.
Phenolic water – It is generated in the by- product plant of coke oven battery and has substantial quantity of dissolved phenol in it. In the steel plant with wet quenching, this water is used for quenching of hot coke. In plant with dry quenching, this water is treated in mechanical, biological, chemical treatment plants before its discharge.
Phenol–formaldehyde – It is one of the oldest commercial synthetic polymers. The polymer is the result of a step-growth polymerization of two simple chemicals: phenol or a mixture of phenols and formaldehyde using an acidic or basic catalyst. Phenol is reactive towards formaldehyde at the ortho and para sites, allowing up to three units of formaldehyde to attach to the aromatic ring. The main product of the reaction between them is the production of methylene bridges between aromatic rings.
Phenol formaldehyde resins – These are synthetic polymers obtained by the reaction of phenol or substituted phenol with formaldehyde. These are used as the basis for Bakelite. Phenolic formaldehyde has been the first commercial synthetic resins. They have been widely used for the production of moulded products such as billiard balls, laboratory countertops, and as coatings and adhesives. They have been at one time the primary material used for the production of circuit boards but have been largely replaced with epoxy resins and fibre glass cloth, as with fire-resistant FR-4 circuit board materials.
Phenol-resorcinol-formaldehyde – It a type of adhesive which is known for its strength and durability. It is mainly used in the structural application area. The dark glue line is strong and resistant to both weather and water.
Phenols – Phenols are organic compounds which have a hydroxyl group attached to one or more aromatic rings in their chemical structure.
Phenomenological laws – These are empirical scientific laws which describe observed phenomena and their relationships without attempting to explain the underlying mechanisms or theoretical causes. Unlike theoretical laws derived from fundamental principles, phenomenological laws capture relationships between macroscopic quantities, such as Fourier’s law of heat conduction or Fick’s law of diffusion. They are useful for modeling and predicting phenomena based on experimental data, even when the exact physical processes are not fully understood.
Phenomenological model – It describes the relationship between material behaviour and process parameters without directly relying on detailed knowledge of the underlying physical mechanisms. It focuses on empirical relationships between observable phenomena, like stress, strain, temperature, and resulting microstructural changes, often using mathematical equations fitted to experimental data.
Phenomenon – It is an observable fact, event, or effect in the real world which the engineers study, measure, and explain to solve problems or create new technologies. It provides the context for engineering work and can be physical (like heat transfer), mechanical (like material creep), or even random, influencing the outcome of processes.
Phenyl – It is a functional group consisting of a cyclic ring of six carbon atoms with the chemical formula –C6H5. It is the substituent form of the cyclo-alkane benzene.
Phenyl ether polymers – These are a class of polymers that contain a phenoxy or a thiophenoxy group as the repeating group in ether linkages. Commercial phenyl ether polymers belong to two chemical classes namely polyphenyl ethers (PPEs) and polyphenylene oxides (PPOs). The phenoxy groups in the former class of polymers do not contain any substituents whereas those in the latter class contain 2 to 4 alkyl groups on the phenyl ring.
Phenyl-silane resins – These are thermosetting copolymers of silicone and phenolic resins. These resins are furnished in solution form.
Phi bonds – These are normally covalent chemical bonds, where six lobes of one involved atomic orbital overlap six lobes of the other involved atomic orbital. This overlap leads to the formation of a bonding molecular orbital with three nodal planes which contain the inter-nuclear axis and go through both atoms.
Phlogopite – It is a magnesium-rich mineral belonging to the mica group, typically having a yellowish-brown to reddish-brown colour. It is a hydrous silicate of potassium, magnesium, and aluminum, and it is frequently found in metamorphic rocks like crystalline limestones and ultrabasic igneous rocks. Phlogopite is also known for its use as an electrical insulator due to its resistance to electricity.
pH meter – It is a device which measures the acidity or alkalinity of a solution by determining its hydrogen ion concentration. It uses a pH electrode, which is a glass probe, and a reference electrode to generate an electrical potential proportional to the solution’s pH level. This reading is then displayed on a digital meter, normally on a scale of 0 to 14, where 7 is neutral, values below 7 are acidic, and values above 7 are alkaline.
pH monitoring – It refers to the process of measuring and tracking the acidity or alkalinity (pH level) of a substance.
pH neutralization – It refers to a chemical reaction where an acid and a base react to form a salt and water, ideally resulting in a solution with a pH closer to 7 (neutral). This reaction effectively reduces the acidity of an acidic solution or the alkalinity of a basic solution, bringing the pH towards neutrality.
Phonograph – It is a record player which is a device that converts the mechanical movements of a stylus in a disk or cylinder recording groove into sound.
Phonon – It is a quasi-particle, collective excitation in a periodic, elastic arrangement of atoms or molecules in condensed matter, specifically in solids and some liquids.
Phosam process – It is a process for ammonia removal from coke oven gas. This process absorbs the ammonia from the coke oven gas using a solution of mono-ammonium phosphate (NH4H2PO4). The process produces saleable anhydrous ammonia. In the Phosam process, ammonia is selectively absorbed from the coke oven gas by direct contact with an aqueous solution of ammonium phosphate in a two-stage spray absorption vessel. Phosam process selectively absorbs ammonia from the coke oven gas through direct contact with an aqueous solution of phosphate, which is added only in minimal quantities. The absorption solution actually contains a mixture of (i) phosphoric acid (H3PO4), (ii) mono ammonium phosphate, (iii) di-ammonium phosphate [(NH4)2HPO4], and (iv) tri-ammonium phosphate [(NH4)3PO4]. The reversible absorption reactions which take place are (i) H3PO4 + NH3 = NH4H2PO4, (ii) NH4H2PO4 + NH3 = (ΝΗ4)2HPO4, and (iii) (NH4)2HPO4 + NH3 = (ΝΗ4)3PO4. The ammonia absorbed is recovered by steam stripping. This regenerates the absorption solution which is returned to the spray absorber. The steam stripping is performed at high pressure of around 1.3 mega pascals. The reason for this is that the reversible reactions which liberate the ammonia from solution are favoured by higher temperatures. Hence, by operating at high pressure (and hence higher temperature), the consumption of stripping steam is minimized. The overhead vapours from the stripper are virtually only water vapour and ammonia. These vapours are condensed and then fed to a fractionating column where anhydrous ammonia is recovered as the condensed overhead product. The fractionator bottoms product, mainly water, leaves the system as effluent.
Phosphate – It is a chemical compound containing phosphorus. It is a key ingredient in fertilizers. Its chemical structure features a tetrahedral arrangement of one phosphorus atom surrounded by four oxygen atoms.
Phosphate-bonded mould – This inorganic binder system, which consists of an acidic, water-soluble, liquid phosphate binder and a powdered metal oxide hardener, has been designed to comply with air quality control regulations. Since its components are inorganic, fumes, smoke, and odour are reduced at pouring and shakeout. The phosphate no-bake binder system has shakeout properties superior to those of the silicate / ester catalyzed no-bake systems. The bonded sand can be reclaimed easily by either shot blast or dry-attrition reclamation units. The hardener component is an odourless, free-flowing powder. It is to be kept dry. In contact with water, it slowly undergoes a mildly alkaline hydration reaction which alters its chemical reactivity and physical state. Under normal ambient conditions, the material is not hydroscopic. Flow properties of the powdered hardener are good. Standard powder feeding equipment can be used to disperse the hardener into sand mixers. Curing characteristics of the phosphate no-bake binder system depend on the ratio of hardener to binder. Varying the level of hardener can typically control strip times from 25 minutes to more than 1 hour Recommended phosphoric acid-base binder levels are from 2.5 % to 3 % for moulds and 3.5 % to 4 % for core production. The hardener level is to be kept within 18 % to 33 % of the binder weight for better results. Sand type also affects cure speed. Strongly alkaline sands such as olivine tend to accelerate the cure rate. Zircon forms an extremely strong and stable bond with phosphate binders, and as a result shakeout is more difficult. High-quality defect-free castings can be produced using the phosphate binder system for moulds and cores with a variety of metals, including gray and ductile irons and different steels. Erosion resistance of both washed and unwashed moulds is very good. Veining resistance is good on unwashed surfaces and can be controlled with the proper coating selection.
Phosphate coating – It is a protective layer applied to steel and zinc surfaces to improve corrosion resistance. It is normally used as a base for paint and in applications to reduce wear in sliding parts. Adherent phosphate coating is formed on a metal by immersion in a suitable aqueous phosphate solution. It is also called phosphatizing.
Phosphate conversion coating – It is a chemical treatment which is applied to steel parts that creates a thin adhering layer of iron, zinc, or manganese phosphates to improve corrosion resistance or lubrication or a foundation for subsequent coatings or painting. It is one of the most common types of conversion coating. The process is also called phosphate coating, phosphatization, phosphatizing, or phosphating. It is also known by the trade name Parkerizing.
Phosphate deposits – These are substantial accumulations of phosphate rock, a sedimentary rock rich in phosphate minerals like apatite, which can be economically extracted for the production of phosphorus. These deposits are an important source for the fertilizer industry.
Phosphate ester – It is an ester derived from an alcohol and phosphoric acid. It is also called organo-phosphate compounds since these molecules have a phosphate group bonded to carbon. Phosphate esters are a class of organic compounds characterized by a central phosphorus atom bonded to three alkoxy or aryloxy groups. They are essentially esters of phosphoric acid and can be represented by the general formula O=P(OR)3, where R represents an alkyl or aryl group. These compounds are widely used in several applications, including as flame retardants, surfactants, and pesticides.
Phosphate glasses – These are a type of inorganic glass mainly composed of phosphorus pentoxide (P2O5) and other chemical components, forming chain-like or crosslinked structures of phosphate anion tetrahedra. They are characterized by their unique properties, including high solubility for rare earth ions, chemical durability, and ability to be used in low-temperature sealing applications.
Phosphate rock – It is a sedimentary rock containing high concentrations of phosphorus, mainly in the form of apatite minerals. It is an important natural resource formed from the accumulation of organic matter on the ocean floor over millions of years and is mined for producing phosphate fertilizers and other chemical products.
Phosphate solution – It is a mixture of metal phosphates dissolved in phosphoric acid, used to create corrosion-resistant coatings on metals such as ferrous metals and zinc, cadmium, and aluminum. These solutions result in the precipitation of metal phosphates which form a chemically bonded film on the metal surface.
Phosphating – It is the forming an adherent phosphate coating on a metal by immersion in a suitable aqueous phosphate solution. It is also called phosphatizing.
Phosphazene – It is a unique class of inorganic-organic materials characterized by high nitrogen and phosphorus content, which improve the thermal and flame-retardant properties of reinforced polymer composites.
Phospho-gypsum – It is a large-volume industrial waste product created during the manufacturing of phosphoric acid. It is a key component in phosphate fertilizers. It is a hydrated calcium sulphate (CaSO4·2H2O), but unlike natural gypsum, it contains impurities such as phosphates, fluorides, heavy metals, and radionuclides, which pose environmental concerns during disposal. While much of it is discarded, phosphor-gypsum has potential uses for soil amendment, and in the construction industry for cement and building materials.
Phosphor bronze, leaded phosphor bronze – It is a hard and strong cast and wrought copper / tin alloys with small, deliberate, phosphorus additions. Wrought alloys contain 4 % to 8 % tin, whilst cast alloys contain 9 % to 12 % tin. Leaded phosphor bronzes, with lead contents up to 20 %, are normally available only as castings. Phosphor bronzes are used for bearing applications. Two common types of bearing bronzes are copper-base alloys containing 5 % to 20 % tin and a small quantity of phosphorus (phosphor bronzes) and copper-base alloys containing up to 10 % tin and up to 30 % lead (leaded bronzes).
Phosphorescence – Phosphorescence is a type of photoluminescence related to fluorescence. When exposed to light (radiation) of a shorter wavelength, a phosphorescent substance glows, absorbing the light and reemitting it at a longer wave-length. It is a type of photo-luminescence in which the time period between the absorption and re-emission of light is relatively long (of the order of 10 to the power -4 to 10 seconds or longer).
Phosphoric acid – It is also known as orthophosphoric acid, or mono-phosphoric acid It is a colourless, odourless phosphorus-containing solid, and inorganic compound with the chemical formula H3PO4. It is normally come across as an 85 % aqueous solution, which is a colourless, odourless, and non-volatile syrupy liquid. It is a major industrial chemical, being a component of several fertilizers.
Phosphoric acid fuel cell (PAFC) – It is a type of fuel cell which uses liquid phosphoric acid as its electrolyte, with porous carbon electrodes and a platinum catalyst to facilitate electrochemical reactions. It is a commercially available. First generation fuel cell which operates at moderately high temperatures (150 deg C to 220 deg C) uses a variety of fuels, and is well-suited for stationary power applications like commercial buildings, though it also has lower efficiency than some other fuel cell types when generating only electricity.
Phosphorized copper – It is the general term applied to copper deoxidized with phosphorus. The normally used term is deoxidized copper.
Phosphor layer – It is the photoactive layer of an intensifying screen which contains tiny phosphor crystals, which emit light when energized by X-rays.
Phosphorus (P) – It has atomic number 15 and atomic weight 30.974. It has density of 1.82 per cubic centimeters. It has a melting point of 44.1 deg C and boiling point of 280 deg C. It is normally considered an undesirable impurity in steels. It is present in varying concentrations in iron ore, is retained in hot metal, but is eliminated early in the steelmaking process. Phosphorus oxidizes readily and is removed from steel as P2O5, which is taken up by the oxidizing slag, before the oxidation of carbon takes place. Phosphorus has embrittlement effects. It increases machinability. It is an undesirable element. It increases strength and hardness and decreases ductility and notch impact toughness of steel. The adverse effects on ductility and toughness are greater in quenched and tempered high carbon steels. Phosphorus levels are normally controlled to low levels. Higher phosphorus is specified in low carbon free-machining steels to improve machinability.
Phosphorus coating – It refer to a phosphor coating, which is a layer of phosphorescent material applied to a surface to emit light after absorbing and re-emitting other wavelengths, such as the yellow phosphor on blue LEDs (light emitting diodes). Alternatively, it can refer to phosphating, a chemical process which forms a protective and adhesive phosphate conversion coating on metal surfaces to provide corrosion resistance and a base for paint.
Phosphorus reversion – It is the reversion of phosphorus from slag to steel which can take place when heating to the aimed temperature, close to the end of the steelmaking process. Phosphorus reversion phenomenon also occurs during slag foaming if the high phosphorus slag has not been removed prior to this operation.
Phosphorus slag – It is a solid, vitrified industrial byproduct from the high-temperature, electric furnace production of yellow phosphorus, mainly composed of calcium and silicon oxides, with trace quantities of phosphorus and fluorine. It is generated in large quantities and, while mostly considered waste, has potential uses as a building material, although its low early strength and long setting times can pose challenges for comprehensive utilization.
Photoacoustic spectroscopy (PAS) – It is an analytical technique which measures the absorption of modulated electromagnetic radiation (like light) by a sample, which is then converted into heat, creating pressure fluctuations detected as acoustic waves (sound). The technique relies on the photoacoustic effect, where absorption leads to thermal expansion and contraction, generating sound waves that can be sensed by a microphone or piezoelectric transducer. Photoacoustic spectroscopy provides a highly sensitive way to study the absorption spectra of both gases and condensed matter, with applications in gas detection and the analysis of opaque or scattering samples.
Photocatalytic coating – It is a surface treatment containing a photocatalyst material, very frequently titanium di-oxide (TiO2), which uses light energy (like jltra-violet or visible light) to trigger chemical reactions, such as the breakdown of organic pollutants, bacteria, and viruses, and to create self-cleaning surfaces. Upon absorbing light, the photocatalyst generates reactive species, like hydroxyl radicals, that are responsible for the degradation of contaminants and the inactivation of microorganisms.
Photocatalytic carbon di-oxide (CO2) reduction – It is the process of converting carbon di-oxide into valuable chemical products, such as methanol, using a photocatalyst and energy from light, often involving water as a reductant in the presence of semiconductor materials like titanium di-oxide (TiO2).
Photocatalytic reactor – It is a device which harnesses the power of light and a photocatalyst to drive chemical reactions, typically to degrade pollutants like organic compounds or produce hydrogen. It works by having a semiconductor catalyst absorb light energy, which then initiates a redox reaction involving photogenerated electrons and holes on the catalyst’s surface to break down pollutants into simpler, less harmful substances such as water and carbon di-oxide.
Photo-cell – It is a light sensor which produces or alters a voltage when light is present.
Photo-chemical degradation – It is the process where materials break down into smaller molecules because of the absorption of light, particularly ultra-violet (UV) radiation, leading to chemical and physical changes. This degradation can cause effects like hardening, embrittlement, and loss of mechanical properties in polymers. It contributes to the breakdown of organic pollutants in the environment.
Photo-chemical machining (PCM) – It is a chemical milling process which is used to fabricate sheet metal components using a photoresist and etchants to corrosively machine away selected areas. This process emerged as an offshoot of the printed circuit board industry. Photo etching can produce highly complex parts with very fine detail accurately and economically. This process offers economical alternatives to stamping, punching, laser or water jet cutting, or wire electrical discharge machining (EDM) for thin gauge precision parts. The tooling is inexpensive and quickly produced. It maintains dimensional tolerances and does not create burrs or sharp edges. It can make a part in hours after receiving the drawing.
Photochemical ozone creation – It refers to the process by which emissions of substances like acetylene (C2H2) and carbon mono-oxide (CO) lead to the formation of ozone, particularly in stages associated with transportation and production. This phenomenon contributes to the formation of photochemical smog and can have detrimental effects on human health and the environment when ozone levels exceed certain thresholds.
Photo-chemical pollution – It refers to the formation of smog, particularly in urban areas, because of the reaction of volatile organic compounds from liquid fuels with sunlight, leading to the production of nitrogen dioxide and high ozone concentrations.
Photochemical smog – It is a brownish-gray haze caused by the action of solar ultraviolet radiation on atmosphere polluted with hydrocarbons and oxides of nitrogen. It contains anthropogenic air pollutants, mainly ozone, nitric acid, and organic compounds, which are trapped near the ground by temperature inversion. These pollutants and also some others can affect human health and cause damage to plants. Photochemical smog often has an unpleasant odor due to some of its gaseous components.
Photocopier – It is a machine which makes copies of documents and other visual images onto paper or plastic film quickly and cheaply. Modern photocopiers use a technology called xerography, a dry process which uses electrostatic charges on a light-sensitive photoreceptor to first attract and then transfer toner particles (a powder) onto paper in the form of an image. The toner is then fused onto the paper using heat, pressure, or a combination of both.
Photocopying – It is dry printing using an electrostatic process to directly or indirectly attract toner, a carbon black pigment in some form of binder to a substrate.
Photo-detection – It is the process of converting light or electro-magnetic radiation into an electrical signal, allowing for the detection and measurement of light intensity or the presence of radiation. This fundamental process is carried out by devices called photo-detectors (or photo-sensors) and is necessary for different applications, including optical communication, imaging, and scientific instrumentation.
Photo-detector – It is a device which detects visible light.
Photo-diode – It is a two-terminal device whose terminal voltage or current changes in response to light.
Photodiode array – It consists of an array of photodiodes of microscopic dimensions, each capable of being coupled to a signal line in turn through an associated transistor circuit adjacent to it on the chip.
Photo-elasticity – It is an optical method for evaluating the magnitude and distribution of stresses, using a transparent model of a part, or a thick film of photoelastic material bonded to a real part.
Photo-electrochemical (PEC) cell – It is device which converts light energy into electrical energy or chemical energy by using a photoactive semiconductor electrode in an electrolyte solution to absorb light, generate electron-hole pairs, and facilitate redox reactions. These cells are used for solar energy conversion, water splitting to produce hydrogen and oxygen, and other photocatalytic applications.
Photo-elastic modulator (PEM) – It is an optical device used to modulate the polarization of a light source. The photoelastic effect is used to change the birefringence of the optical element in the photoelastic modulator. The basic design of a photoelastic modulator consists of a piezoelectric transducer and a half wave resonant bar; the bar being a transparent material (now most commonly fused silica). The transducer is tuned to the natural frequency of the bar. This resonance modulation results in highly sensitive polarization measurements. The fundamental vibration of the optic is along its longest dimension.
Photo-electric effect – It is the emission of electrons from a material caused by electro-magnetic radiation such as ultra-violet light. Electrons emitted in this manner are called photo-electrons. The phenomenon is studied to draw inferences about the properties of atoms, molecules and solids. The effect has found use in electronic devices specialized for light detection and precisely timed electron emission.
Photo-electric sensor – It is a sensor in a conveyor system which uses light beams for material detection, demanding regular inspections for accurate sensing and preventing false readings.
Photo-electric electron-multiplier tube – – It is a device in which incident electromagnetic radiation creates electrons by the photoelectric effect. These electrons are accelerated by a series of electrodes called dynodes, with secondary emission adding electrons to the stream at each dynode. It is also called photomultiplier tube.
Photo-emission electron microscope – It is also known as a photoelectron microscope. It is a surface-sensitive imaging technique which creates contrast by measuring differences in the emission of photoelectrons from a material’s surface, which are generated when the sample is exposed to light or X-rays. Photoemission electron microscope is a type of electron microscope which uses these emitted photoelectrons to form magnified images of the sample’s surface, revealing information about its chemical, electronic, and magnetic properties with high spatial resolution.
Photo-emission electron microscopy – It is also called photo-electron microscopy (PEM). It is a type of electron microscopy which utilizes local variations in electron emission to generate image contrast. The excitation is normally produced by ultraviolet light, synchrotron radiation or X-ray sources. Photo-emission electron microscopy measures the coefficient indirectly by collecting the emitted secondary electrons generated in the electron cascade which follows the creation of the primary core hole in the absorption process. Photo-emission electron microscopy is a surface sensitive technique since the emitted electrons originate from a shallow layer.
Photo eye – It is a sensor which is designed to identify the presence of a load within a conveyor system.
Photography – It is the application and practice of creating images by recording light, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is used in several fields. Typically, a lens is used to focus the light reflected or emitted from objects into a real image on the light-sensitive surface inside a camera during a timed exposure. With an electronic image sensor, this produces an electrical charge at each pixel, which is electronically processed and stored in a digital image file for subsequent display or processing.
Photolithography – It is a microfabrication technique used to transfer geometric patterns onto a substrate. It involves using light to create a pattern on a light-sensitive material (photoresist) on a substrate, which is then used to selectively remove material from the substrate through processes like etching. This allows for the creation of intricate patterns, particularly in the fabrication of microelectronic circuits and other microdevices. Photolithography is a crucial process in semiconductor manufacturing, enabling the creation of transistors and other components on integrated circuits. It is also used in other fields like MEMS (micro-electro-mechanical systems) and microfluidics.
Photolithographic patterning – It is a microfabrication process which uses light to transfer a geometric design from a photomask to a photoresist-coated substrate, such as a silicon wafer. Light exposure creates a pattern in the photoresist, which is then developed by chemically removing either the exposed (positive photoresist) or unexposed (negative photoresist) areas. This patterned photoresist then acts as a stencil for subsequent etching or deposition steps to create micro-electronic circuits and other small, intricate devices.
Photo-luminescence – It is the re-emission of light absorbed by an atom or molecule. The light is emitted in random directions. There are two types of photo-luminescence namely fluorescence and phosphorescence.
Photo-macrograph – It is a macrograph produced by photographic means.
Photo-meter – It is a device so designed that it measures the ratio of the radiant power of two electro-magnetic beams. It is an instrument which measures light.
Photo-micrograph – It is a micrograph made by photographic means.
Photo-microscopy – Prior to the development of photographic attachments, microstructures were to be sketched. Although the need for such documentation is no more there, sketching remains useful as a teaching method. Photo-microscopy is important in metallography, since the photo-micrograph can faithfully reproduce the detail observed for others to view. With the equipment presently available, high-quality micrographs are easily produced. However, this needs careful attention to sample preparation, etching, and use of the microscope. Reproduction of false microstructures is all too common and has caused inaccurate interpretations, rejection of good materials, and faulty conclusions in failure analyses.
Photo-multiplier tube – It is a device in which incident electromagnetic radiation creates electrons by the photoelectric effect. These electrons are accelerated by a series of electrodes called dynodes, with secondary emission adding electrons to the stream at each dynode. It is also known as multiplier phototube, electron multiplier phototube, and photoelectric electron-multiplier tube.
Photon – It is a carrier of electro-magnetic radiation of all wave-lengths (such as gamma rays and radio waves).
Photonic devices – These devices refer to technologies which utilize photons for tasks such as high-speed data transmission and routing, capitalizing on their large optical frequencies and corresponding information bandwidths which are significantly higher than those of electronic devices.
Photonics – It refers to technologies which utilize photons, or light beams, to store, transfer, and manipulate information, analogous to how electronics use electrons. This includes devices such as photonic switches, P-gates, amplifiers, modulators, and integrated circuits. It is the technology of conveying information through light or infrared radiation.
Photon scanning tunneling micro-scope (PSTM) – It is analogous to the operation of an electron scanning tunneling microscope, with the primary distinction being that photon scanning tunneling micro-scope involves tunneling of photons instead of electrons from the sample surface to the probe tip. A beam of light is focused on a prism at an angle higher than the critical angle of the refractive medium in order to induce total internal reflection within the prism. Although the beam of light is not propagated through the surface of the refractive prism under total internal reflection, an evanescent field of light is still present at the surface.
Photophoresis – It is the phenomenon where particles in a liquid are accelerated in the direction of a laser beam when irradiated, with the migration velocity being proportional to the particle size and dependent on the particle’s refractive index.
Photo-resist – It is a radiation-sensitive material which, when properly applied to a variety of substrates and then properly exposed and developed, masks portions of the substrate with a high degree of integrity. It is also a photo-sensitive coating which is applied to a laminate and subsequently exposed through a photo tool (film) and developed to create a pattern that can be either plated or etched.
Photo-resistor – It is a resistor whose resistance varies when light strikes it.
Photosynthesis – It is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabolism. Photosynthesis normally refers to oxygenic photosynthesis, a process which produces oxygen. Photosynthetic organisms store the chemical energy so produced within intracellular organic compounds (compounds containing carbon) like sugars, glycogen, cellulose, and starches. For use this stored chemical energy, an organism’s cells metabolize the organic compounds through cellular respiration. Photosynthesis plays a critical role in producing and maintaining the oxygen content of the earth’s atmosphere, and it supplies most of the biological energy necessary for complex life on earth.
Photo-transistor – It is a transistor which is sensitive to light.
Photovoltaic cell (PV cell) – It is also known as solar cell. It is an electronic device which converts the energy of light directly into electricity by means of the photovoltaic effect. It is a form of photoelectric cell, a device whose electrical characteristics (such as current, voltage, or resistance) vary when it is exposed to light. Individual photovoltaic cell devices are frequently the electrical building blocks of photovoltaic modules, known as solar panels. Photovoltaic cells consist of crystalline silicon, or cadmium telluride thin-film solar cells. The common single-junction silicon solar cell can produce a maximum open-circuit voltage of around 0.5 volts to 0.6 volts. Photovoltaic cells can operate under sunlight or artificial light. In addition to producing energy, they can be used as a photodetector (for example infrared detectors), detecting light or other electromagnetic radiation near the visible range, or measuring light intensity.
Photovoltaic effect – It is the generation of voltage and electric current in a material upon exposure to light. It is a physical phenomenon. The photovoltaic effect is closely related to the photoelectric effect. For both phenomena, light is absorbed, causing excitation of an electron or other charge carrier to a higher-energy state. The main distinction is that the term photoelectric effect is now normally used when the electron is ejected out of the material (normally into a vacuum) and photovoltaic effect used when the excited charge carrier is still contained within the material. In either case, an electric potential (or voltage) is produced by the separation of charges, and the light has to have a sufficient energy to overcome the potential barrier for excitation.
Photovoltaic (PV) cell efficiency – It is the ratio of the electrical power output to the incident solar energy input which a solar cell converts into usable electricity. It is expressed as a percentage and indicates how effectively the cell transforms sunlight into a useful electrical current. A higher efficiency rating means more electricity is produced from the same amount of sunlight, making the technology more effective.
Photovoltaic (PV) cell materials – These are semiconductor substances, mainly silicon, which are used to build solar cells, which convert sunlight directly into electricity. When photons from sunlight strike these materials, they excite electrons, causing them to flow and create an electric current through the photovoltaic effect. Other semiconductor materials used include cadmium telluride (CdTe) and copper indium gallium diselenide (CIGS), as well as emerging technologies like perovskites and organic photovoltaics.
Photovoltaic (PV) junction box – It is also known as the solar panel junction box. It is a box which enables electrical connections to be made between the solar cell array and the solar charge control device composed of solar cell modules. The Photovoltaic junction box is a specific structural form which combines electrical design, mechanical design, and material science into one complete design. It connects the power generated by solar cells to the external line.
Photovoltaic (PV) module – It is also known as a solar panel. It is an assembly of interconnected solar cells which converts sunlight directly into electricity. These cells are typically made of semiconductor materials, such as silicon, which absorb photons from sunlight to generate a flow of electrons, producing direct current (DC) electricity through the photovoltaic effect. Encased in protective materials like tempered glass and a robust frame, photovoltaic modules are designed to withstand environmental conditions and provide a usable output of power.
Photovoltaic (PV) panels – These are normally known as solar panels. These are devices which convert sunlight directly into electricity using the photovoltaic effect. They consist of several individual solar cells, typically made of semiconducting materials like silicon. When light strikes these cells, it dislodges electrons, which are then captured by metal contacts to generate direct current (DC) electricity. This direct current electricity is then converted to alternating current (AC) by an inverter.
Photovoltaics (PV) – It is the conversion of light into electricity using semi-conducting materials which show the photovoltaic effect.
Photovoltaic system – It uses solar modules, each comprising a number of solar cells, which generate electrical power. Photovoltaic installations can be ground-mounted, rooftop-mounted, wall-mounted or floating. The mount can be fixed or use a solar tracker to follow the sun across the sky.
Phyllite – It is a foliated metamorphic rock characterized by a silky, golden sheen from fine-grained mica, and it forms as a result of the further metamorphism of slate, representing a stage between slate and schist in the metamorphic process. Composed mainly of quartz, fine-grained mica (such as sericite), and chlorite, it shows a texture with a preferred orientation of mica crystals, giving it excellent fissility (tendency to split into thin sheets).
Phyllosilicates – These are also known as sheet silicates. These are a group of silicate minerals characterized by a layered structure where silicate tetrahedra are arranged in sheets. These minerals are important in various geological and environmental contexts, including weathering, sedimentary rocks, and even technological applications.
Physical absorption – For physical absorption, carbon di-oxide is physically absorbed in a solvent as per Henry’s Law. The absorption capacity of organic or inorganic solvents for carbon di-oxide increases with increasing pressure and with decreasing temperatures. Absorption of carbon di-oxide occurs at high partial pressures of carbon di-oxide and low temperatures. The solvents are then regenerated by either heating or pressure reduction. The advantage of this method is that it needs relatively little energy, but the carbon di-oxide is to be at high partial pressure.
Physical access – It refers to the ability to enter and interact with a physical location, asset, or device, and in the context of security, it means controlling who can physically enter a restricted space or gain hands-on control of a system. Physical access control systems use different mechanisms, such as keys, access cards, or biometrics (like fingerprints), to restrict entry to authorized individuals and prevent unauthorized intrusions.
Physical accounting – It is the practice of accounting for natural resources and the environment using physical units like weight, area, or number. It is used to assess the environmental impact of economic activities.
Physical adsorption – It is also called physisorption. It is the binding of an adsorbate to the surface of a solid by forces whose energy levels approximate those of condensation.
Physical assets – These are tangible items which can be seen, touched, and used. They are a necessary part of the operations of the organization. They include buildings, plant and equipment, facilities, vehicles, and land.
Physical beneficiation – It is a process which separates and removes impurities (gangue minerals) from raw materials, like coal or ore, by using differences in their physical properties, such as density, magnetic susceptibility, or electric conductivity. This process does not alter the chemical composition of the material but rather uses physical forces like gravity, magnetism, or electricity to concentrate the desired valuable minerals, resulting in a higher-grade product.
Physical catalyst – It is the radiant energy capable of promoting or modifying a chemical reaction.
Physical chemistry – It is the study of macroscopic and microscopic phenomena in chemical systems in terms of the principles, practices, and concepts of physics such as motion, energy, force, time, thermodynamics, quantum chemistry, statistical mechanics, analytical dynamics and chemical equilibria. Physical chemistry, in contrast to chemical physics, is predominantly (but not always) a supra-molecular science, as the majority of the principles on which it was founded relate to the bulk rather than the molecular or atomic structure alone (for example, chemical equilibrium and colloids).
Physical crack size (ap) – In fracture mechanics, it is the distance from a reference plane to the observed crack front. This distance can represent an average of several measurements along the crack front. The reference plane depends on the sample form, and it is normally taken to be either the boundary or a plane containing either the load line or the centre-line of a sample or plate.
Physical etching – It is the development of microstructure through removal of atoms from the surface or lowering the grain surface potential.
Physical law – It is also called scientific law, or law of nature. It is a scientific generalization based on empirical observations of physical behaviour. Empirical laws are typically conclusions based on repeated scientific experiments over several years, and which have become accepted universally within the scientific community. The production of a summary description of nature in the form of such laws is a fundamental aim of science. Physical laws are distinct from the law, either religious or civil, and are not to be confused with the concept of natural law. Nor are the ‘physical law’ be confused with ‘law of physics’ – the term ‘physical law’ normally covers laws in other sciences (e.g., biology) as well.
Physical metallurgy – It is the science and technology dealing with the properties of metals and alloys, and of the effects of composition, processing, and environment on those properties.
Physical modelling – Physical modelling of the continuous casting process such as using water to simulate liquid steel enables considerable insight into the flow behaviour of the liquid steel during the continuous casting process. Previous understanding of fluid flow in the continuous casting process has come about mainly through experiments using physical water models. This technique is a useful way to test and understand the effects of new configurations before implementing them in the process. A full-scale model has the important additional benefit of providing operator training and understanding.
Physical objective aperture – In electron microscopy, it is a metal diaphragm centrally pierced with a small hole used to limit the cone of electrons accepted by the objective lens. This improves image contrast, since highly scattered electrons are prevented from arriving at the Gaussian image plane and hence cannot contribute to background fog.
Physical parameters – These are numerical values which describe the size, energy output, and other characteristics of an object or system. These parameters can be used to measure the strength of magnetic fields, temperatures, and densities.
Physical phenomenon – It refers to observable events or occurrences in the nature which cannot be explained by classical theory. As an example, heat is a physical phenomenon, which is defined as the transfer of thermal energy across a well-defined boundary around a thermodynamic system.
Physical pollution – It consists of the introduction or presence of harmful substances or forces in the environment which cause damage to the environment and its processes because of their material actions, as through vibration, thermal alteration, or electro-magnetic radiation.
Physical properties – It is the properties of a metal or alloy which are relatively insensitive to micro-structure and can be measured without the application of force, e.g., density, electrical conductivity, coefficient of thermal expansion, magnetic permeability, and lattice parameter. It does not include chemical reactivity. It does not include chemical reactivity. The modulus of elasticity can be considered a physical property, since it is structure-insensitive at the engineering scale of measurement. The modulus of elasticity is controlled by interatomic binding forces, and it can be determined from physical testing (e.g., by the speed of sound and density of a material).
Physical quality – It is also called structural quality, which is applicable when specified strength and elongation values are needed in addition to bend tests.
Physical quantity – It is a property of a material or system that can be quantified by measurement. A physical quantity can be expressed as a value, which is the algebraic multiplication of a numerical value and a unit of measurement. For example, the physical quantity mass, symbol ‘m’, can be quantified as ‘m=n’ kilogram, where ‘n’ is the numerical value and kilogram is the unit symbol. Quantities which are vectors have, besides numerical value and unit, direction, or orientation in space.
Physical solvent process – It is a type of industrial gas purification technique where acid gases or other contaminants are removed from a gas stream by dissolving them into a physical solvent, rather than through a chemical reaction. These processes work based on the solubility of gases, which is driven by high partial pressures and low temperatures. After absorption, the solvent is regenerated to release the captured gases, typically by reducing the pressure, which is an energy-efficient method compared to heating-intensive chemical processes.
Physical stores – Physically stores can be centralized stores or decentralized stores. These stores are named based on the size and location of the store. Examples are central store, sub store, department store, site store, transit stores, receipt store, intermediate store, open yard store, and covered store etc.
Physical testing It consists of methods which are used to determine the entire range of the material’s physical properties of a material. In addition to density and thermal, electrical, and magnetic properties, physical testing methods can be used to assess simple fundamental physical properties such as colour, crystalline form, and melting point.
Physical vapour deposition (PVD) – It is a coating process whereby the deposition species are transferred and deposited in the form of individual atoms or molecules. The most common physical vapour deposition methods are sputtering and evaporation. Sputtering, which is the principal physical vapour deposition process, involves the transport of a material from a source(target) to a substrate by means of the bombardment of the target by gas ions which have been accelerated by a high voltage. Atoms from the target are ejected by momentum transfer between the incident ions and the target. These ejected particles move across the vacuum chamber to be deposited on the substrate. Evaporation, which has been the first physical vapour deposition process used, involves the transfer of material to form a coating by physical means alone, essentially vapourization. The streaming vapour is generated by melting and evaporating a coating material source bar, by an electron beam in a vacuum chamber. Since both of these methods are line-of-sight processes, it is necessary to use specially shaped targets or multiple evaporation sources and to rotate or move the substrate uniformly to expose all areas. Physical vapour deposition coatings are used to improve the wear, friction, and hardness properties of cutting tools and as corrosion-resistant coatings.
Physical work environment – It is the part of the work-place facility which can be detected by human senses or by physical, chemical, biological, or ergonomic assessment including the structure, air, machines, furniture, products, chemicals, materials and processes which are present or which occur in the workplace, and which can affect the physical or mental safety, health, and well-being of workers. If the workers perform their tasks outdoors or in a vehicle then that location is their physical work environment.
Physicochemical characterization – It is the systematic evaluation and definition of a material’s physical and chemical properties, encompassing aspects like size, shape, composition, purity, stability, surface characteristics, and structure. This process uses several analytical techniques to understand how these properties influence a material’s behaviour, function, and interactions with its environment, which is crucial for applications in nano-materials, and other fields.
Physicochemical interaction – It is a reaction, association, or phenomenon which involves both the physical and chemical properties of substances or systems, leading to altered behaviour, stability, or function. These interactions stem from the unique physicochemical characteristics (like chemical structure, solubility, and charge) of the involved components.
Physics – It is the scientific study of matter, its fundamental constituents, its motion and behaviour through space and time, and the related entities of energy and force. It is one of the most fundamental scientific disciplines.
Physisorption – It is the binding of an adsorbate to the surface of a solid by forces whose energy levels approximate those of condensation.
Pi – It is a mathematical constant which is approximately equal to 3.14159, i.e., the ratio of a circle’s circumference to its diameter. It appears in several formulae, and some of these formulae are normally used for defining pi, to avoid relying on the definition of the length of a curve.
Pi bonding – It consists of covalent bonding in which the atomic orbitals overlap along a plane perpendicular to the sigma bond(s) joining the nuclei of two or more atoms.
Pi bonds – These are covalent chemical bonds, in each of which two lobes of an orbital on one atom overlap with two lobes of an orbital on another atom, and in which this overlap occurs laterally. Each of these atomic orbitals has an electron density of zero at a shared nodal plane which passes through the two bonded nuclei. This plane also is a nodal plane for the molecular orbital of the pi bond. Pi bonds can form in double and triple bonds but do not form in single bonds in most cases.
Pick – It is an individual filling yarn, running the width of a woven fabric at right angles to the warp. It is also called fill, woof, and weft.
Pick count – It consists of the number of filling yarns per centimeter of woven fabric.
Picket line – A reference line, marked by pickets or stakes, established on a land for mapping and survey purposes.
Pickle – It means the chemical removal of surface oxides (scale) and other contaminants such as dirt from iron and steel by immersion in an aqueous acid solution. The most common pickling solutions are sulphuric acid and hydrochloric acid.
Pickle liquor – It is a spent acid-pickling bath.
Pickle stain – It is the discolouration of metal because of the chemical cleaning without adequate washing and drying.
Pickling – It is the most common of several processes used to remove the scale from steel surfaces. The term pickling refers to the chemical removal of scale by immersion in an aqueous acid solution. Pickling is the chemical removal of surface oxides (scale) and other contaminants such as dirt from iron and steel by immersion in an aqueous acid solution. The most common pickling solutions are sulphuric acid and hydrochloric acid.
Pickling cracks – Pickling is chemical surface cleaning operation (using acids) used to remove unwanted scale. Picking cracks are hydrogen induced cracks caused by the diffusion of the hydrogen generated at the surface into the base metal. Such cracks mostly occur in materials having high residual stresses such as hardened or cold worked metals.
Pickling line – It is a manufacturing process which uses acid solutions to remove scale from the surface of hot strips which has been rolled in hot strip mill. In this process, hot strip undergoes through a series of value-added processing steps. The first of which involves unwinding the hot rolled coil and the strip running it through a series of acid tanks and rinse tanks. Basically, there are three types of pickling lines. These are (i) push and pull type pickling line, (ii) semi-continuous pickling line, and (iii) continuous pickling line. This process prepares the metal for further manufacturing steps
Pickling solutions – For carbon steel, sulphuric (H2SO4) acid is used in most batch pickling operations, whereas hydrochloric (HCl) acid has become the pickling agent of choice, as of 1994, for continuous operations with hot rolled strip. Pickling with hydrochloric acid started in 1964 and slowly many picking installations have switched over to hydrochloric acid pickling. Mixtures of hydrochloric and sulphuric acids have also been used in batch pickling, frequently by adding rock salt (NaCl) to a sulphuric acid pickling bath. Such practices are expected to give the bright, pickled steel surface characteristics associated with hydrochloric acid and to increase pickling rates, but not without some drawbacks. The proportion of hydrochloric to sulphuric acids which is needed to achieve the rapid scale removal rate that is possible with hydrochloric alone is too high to be economical, and the mixed acids cannot be properly handled by many of the spent pickle liquor disposal methods now in use. The advantages of sulphuric acid pickling are (i) acid can be renewed more frequently, (ii) raising temperature allows lower acid concentrations to pickle effectively, (iii) ease of recovering iron sulphate (FeSO4), and (iv) the rate of pickling can be controlled by varying the temperature. The disadvantages of sulphuric acid pickling are (i) higher acid attack on base steel, (ii) higher hydrogen diffusion into the steel, (iii) pickling residues are more adherent, and (iv) acid solution is to be heated. The advantages of hydrochloric acid pickling are (i) reduction in heating costs since pickling solutions are used at room temperature, (ii) more extensive removal of scale, (iii) lesser penetration of hydrogen by diffusion, and (iv) lesser deposition of iron salts on the pickled surface. The disadvantages of hydrochloric acid pickling are (i) generation of fumes when heated above ambient temperatures, (ii) acid recovery systems are expensive, (iii) more corrosive toward equipment, and (iv) higher disposal costs than sulphuric acid.
Pick-off – It is an automatic device for removing a finished part from the press die after it has been stripped.
Pick-up – It is the transfer of metal from tools to part or from part to tools during a forming operation. It also consists of small particles of oxidized metal adhering to the surface of a mill product. It is also irregular surface roughness or damage caused by adhesion and subsequent fracture or tearing between the forming tools and the work-piece.
Pick-up, repeating – It is repeating depression caused by a particle adhering to a rotating roll over which the metal has passed.
Pick-up, roll – It consist of small particles of metal and metal oxide generated in the roll bite, which subsequently transfer to the rolled product. It can be distributed uniformly and / or in streaks.
Picogram – It is one trillionth of a gram.
Picosecond laser – It is a type of ultrafast laser which emits optical pulses with durations lasting only a few picoseconds (trillionths of a second). This extremely short pulse duration allows picosecond lasers to deliver high peak power.
Picral – It is a metallurgical etchant for the microscopic study of heat-treated steels. It is an excellent etchant for revealing certain micro-structural constituents in steel. It is recommended for steels with ferrite and carbide structures. Picral consists of 4 grams picric acid, 100 milli-litre ethanol or methanol (95 % or absolute, use of absolute alcohol only when acid contains 10 % or more moisture), and 4 drops or 5 drops 17 % zephiran chloride (wetting agent).
Picric acid – It is an organic compound with the formula (O2N)3C6H2OH. Its IUPAC name is 2,4,6-trinitrophenol (TNP). It has bitter taste. It is one of the most acidic phenols. Like other strongly nitrated organic compounds, picric acid is an explosive, which is its main use. It is used in picral etchant. It has also been used as medicine (antiseptic, burn treatments) and as a dye.
Pictorial diagram – It refers to a visual representation of a process plant, which can include different types such as block flow diagrams (BFD), process flow diagrams (PFD), and piping and instrumentation diagrams (P&ID), each providing different levels of detail about the plant’s operations.
Pidgeon process – It is a process for production of magnesium by reduction of magnesium oxide with ferro-silicon under vacuum. It is a silico-thermic process, meaning silicon is used as the reducing agent. The process involves heating a mixture of calcined dolomite and ferrosilicon in a retort at high temperatures (around 1,150 deg C to 1,200 deg C) under vacuum. Magnesium vapour is produced, which is then condensed and collected. This process is known for its labour-intensive nature and reliance on several small retorts.
Pie chart – It is used to represent nominal data (in other words, data classified in different categories). It visually represents a distribution of categories. A pie chart needs a list of categorical variables and the numerical variables. Here, the term ‘pie’ represents the whole and the ‘slices’ represents the parts of the whole. The pie chart is also is known as ‘circle graph’ since it divides the circular statistical graphic into sectors or slices in order to illustrate the numerical data. The pie chart is normally the most appropriate format for representing information grouped into a small number of categories. It is also used for data which have no other way. The application of 3D effects on a pie chart makes distinguishing the size of each slice difficult. Even if slices are of similar sizes, slices farther from the front of the pie chart can appear smaller than the slices closer to the front because of the false perspective. Pie chart contains different segments and sectors in which each sector forms a certain portion of the total (percentage). Each sector denotes a proportionate part of the whole. The total of all the data is equal to 360-degree. The total value of the pie is always 100 %. Fig 3 shows pie charts. It also shows comparison of simple pie chart versus 3D pie chart.
Pi electron – It is an electron that participates in pi bonding.
Pier – It is a raised structure which rises above a body of water and normally juts out from its shore, typically supported by piles or pillars, and provides above-water access to offshore areas.
Pierce and draw process – It is similar to the push bench process. This process is designed for the manufacture of seamless hollow components combining large dimensions with large wall thicknesses. The starting materials are ingots which are heated to forming temperature and then formed into a cylinder on a vertical hydraulic piercing press. This is then elongated to its final size on a horizontal hydraulic drawing press using a mandrel which corresponds to the requisite inside diameter of the hollow component. Together with the mandrel, the hollow shell is sequentially pushed through a series of drawing dies of decreasing diameter until the requisite diameter is attained.
Pierce and pilger process –In this process input rounds are heated in a rotary hearth furnace to a temperature in the range of 1,250 deg C to 1,300 deg C. From the furnace the rounds are descaled by high pressure water jets and fed to the cross-roll piercing mill where they are pierced to produce a thick-walled hollow shell. In this process the material is elongated to between 1.5 times and 2 times and cross section reduces between 33 % and 50 %. The piercing mill features two specially contoured work rolls which are driven in the same direction of rotation. The axes are inclined by approximately 3-degree to 6-degree in relation to the horizontal stock plane. The roll gap is normally closed by a non-driven support roll at the top and a support shoe at the bottom. A piercing point which functions as an internal tool is located at the centre of the roll gap and is held in position by an external thrust block through a mandrel. The thick-walled hollow shell after the cross-roll piercing operation is rolled out further in the pilgering stand to produce the finished pipe. The elongation ratio during the pilgering process lies between 5 and 10, and is accompanied by a reduction in cross section of around 80 % to 90 %. The pilgering stand has two rolls (sometimes called dies because of their forging action) with a tapered pass around their circumference. The rolls rotate counter to the direction of the material flow. The work pass encompasses between 200-degree to 220-degree of the roll circumference and consists of the tapered inlet, an even, cylindrical polishing pass which blends into a larger clearance for releasing the work piece. Pilgering process is a stepwise rolling cum forging process with its recurring backward and forward motion. After the completion of the pilgering process, the finished pipe is stripped from the mandrel. The unworked part of the hollow shell known as pilger head is cut off by a hot saw. The pipe is then fed into a sizing or a reducing mill after reheating it in a furnace. The sizing mill produces a precise outside diameter as well as improves the concentricity of the pipe. It normally consists of three stands with two high or three high roll arrangements. The work rolls form a closed pass, with (in multi stand configurations) each stand pass being off set at an angle to the previous pass.
Pierced cylinder – It refers to a cylinder which has been specifically designed to create a precise hole or opening in a work-piece. It is frequently used in piercing or forming operations where a non-shock force is desired to minimize tool wear and part deformation. These cylinders utilize an air-over-oil intensification principle to achieve the needed force, offering advantages like low impact, force control, compact design, and automatic compensation for varying part positions.
Piercing – It is the general term for cutting (shearing or punching) openings, such as holes and slots, in sheet material, plate, or parts. This operation is similar to blanking. The difference is that the slug or pierce produced by piercing is scrap, while the blank produced by blanking is the useful part.
Piercing and draw process – In this process, the heated mould cast polygonal ingots are formed into a cylinder with integral bottom on a vertical, hydraulic piercing press. This is then elongated to its final size on a horizontal hydraulic drawing press using a mandrel which corresponds sequentially pushed through a series of drawing die of decreasing diameter until the requisite outside diameter has been attained.
Piezoelectric ceramic materials – These are a type of piezoelectric material which can generate electrical signals in response to mechanical stress and can undergo changes in size when subjected to an electric field. They show characteristics such as high response speed and small strain, making them suitable for applications in sensors and actuators. These are based on modified lead zirconate titanate (PZT) and barium titanate. The designations of ‘soft’ and ‘hard’ piezo ceramics refer to the mobility of the dipoles or domains and hence also to the polarization and depolarization behaviour. For actuator applications, ferroelectrically soft piezoceramics with low polarity reversal field strengths are used. Ferroelectrically hard piezoceramics materials are mainly used in high-power acoustic applications.
Piezoelectric coefficient – It is the measure of volume change in a piezoelectric material when subjected to an electric field.
Piezo-electric effect – It is the reversible interaction, shown by some crystalline materials, between an elastic strain and an electric field. The direction of the strain depends on the polarity of the field or vice versa. It is the production of a voltage in response to mechanical pressure or mechanical deformation. The piezo-electric effect results from the linear electro-mechanical interaction between the mechanical and electrical states in crystalline materials with no inversion symmetry. The piezoelectric effect is a reversible process, i.e., the materials showing the piezo-electric effect also show the reverse piezo-electric effect, the internal generation of a mechanical strain resulting from an applied electric field. As an example, lead zirconate titanate crystals generate measurable piezo-electricity when their static structure is deformed by around 0.1 % of the original dimension. Conversely, those same crystals change around 0.1 % of their static dimension when an external electric field is applied. The inverse piezo-electric effect is used in the production of ultra-sound waves.
Piezo-electricity – It is the electric charge which accumulates in certain solid materials, such as crystals, certain ceramics, and biological matter, and different proteins in response to applied mechanical stress.
Piezoelectric materials – These are defined as substances which generate an electric charge differential along an axis of polarization when subjected to mechanical strain (direct piezoelectric effect) and deform when an electric field is applied along the same axis (converse piezoelectric effect).
Piezo-electric motor – It is a type of motor which uses piezoelectric elements to generate force.
Piezo-electric pressure measurement – The principle of piezo-electric pressure measurement is based on the physical effect of the same name, only found in some non-conductive crystals, e.g. mono-crystalline quartz. If such a crystal is exposed to pressure or tensile force in a defined direction, certain opposed surfaces of the crystal are charged, positive and negative, respectively. Because of a displacement in the electrically charged lattice elements, an electric dipole moment results which is indicated by the (measurable) surface charges. The charge quantity is proportional to the value of the force. Its polarity depends on the force direction. Electrical voltage created by the surface charges can be measured and amplified. The piezo-electric effect is only suitable for the measurement of dynamic pressures. In practice, piezo-electric pressure measurement is restricted to specialized applications.
Piezo-resistive effect – It is the change in electrical resistance of a material, such as a semiconductor or metal, when it is subjected to mechanical stress or strain. This change in resistance occurs because of two primary factors namely changes in the material’s physical dimensions (like length and cross-sectional area) and, more significantly in semiconductors, changes in the material’s intrinsic electrical resistivity because of the altered energy band structures and carrier mobility.
Piezo-resistive pressure measurement – The principle of piezo-resistive pressure measurement is similar to the principle of resistive pressure measurement. However, since the strain gauges used for this measuring principle are made of a semi-conductor material, their deflection because of the elongation or compression results primarily in a change in resistivity. As per the equation of the resistance of an electric conductor, the electrical resistance is proportional to the resistivity. While the piezo-resistive effect in metals is negligible and hence effectively insignificant within resistive pressure measurement, in semi-conductors such as silicon it exceeds the effect of the variation of length and cross-section by a factor between 10 and 100. Because of the magnitude of the piezo-resistive effect, piezo-resistive sensors can also be used in very low-pressure ranges. However, due to strong temperature dependency and manufacturing process-related variation, individual temperature compensation of every single sensor is needed.
Piezo-resistive sensor – A piezo-resistive sensor has a far more complex structure. The sensor element is made of a silicon chip. This chip consists of a diaphragm, structured with piezo-resistive resistors, which deflects under pressure. The chip has a surface area of only a few square millimeters and is thus much smaller than, for example, the diaphragms of metal thin-film or ceramic thick film sensors. The piezo chip is very susceptible to environmental influences and, hence, is to be hermetically encased in majority of the cases. For this reason, it is installed into a stainless-steel case which is sealed using a thin flush stainless-steel diaphragm. The free volume between the piezo chip and the external diaphragm is filled with a transmission fluid. Synthetic oil is normally used for this. In an encased piezo-resistive sensor, the pressure medium is only in contact with the stainless-steel diaphragm, which then transmits the pressure through the oil to the internal chip’s diaphragm.
Piezo-resistive pressure transducer – It is a device which measures pressure by exploiting the piezo-resistive effect, where the electrical resistance of a material changes when mechanical strain is applied. It consists of a diaphragm that flexes under pressure, a piezo-resistor (a strain gauge) attached to it which changes resistance with the strain, and a Wheatstone bridge circuit that converts this resistance change into a measurable electrical output voltage.
Piezo-resistors – These are materials whose resistance changes because of the alterations in their band structure, leading to variations in resistivity, normally observed in silicon and germanium.
Pig – It is a metal casting used in remelting. In nuclear power plant, pig is a container used to ship or store radioactive materials. The thick walls of this shielding device, which are normally made of lead or depleted Uranium, protect the person handling the container from radiation. Large containers used for spent fuel storage are normally called casks. It is also an implement which is used for cleaning rust and alien substances from a piping system.
Pig casting machine (PCM) – It is a piece of equipment, normally an inclined chain conveyor system, which solidifies hot metal (liquid iron) from a blast furnace into smaller, manageable ingots called ‘pigs’. The machine works by continuously pouring hot metal into a series of moulds attached to a circulating conveyor belt, which then cools the metal with air and water before the solidified pieces are automatically released for transport and storage. Pig casting machine consists of four main parts namely (i) machine head, (ii) machine tail, (iii) rollers and link chain, and (iv) device to handle stickers. The machine head has the driving system which is composed of the set of variable speed-controlled motor, gear reducer and sprocket. At the machine tail take-up device is provided on the tail sprocket shaft to give appropriate tension to the link chain. The pig casting machine strand is an endless chain carrying the pig moulds. The strands are placed at an inclination. The level of the inclination is decided on the height needed for receiving the hot metal and for discharging the cast pig iron into the flat cars. The hot metal is poured in the metal transfer launder of the pig casting machine, through which the hot metal is discharged into the traveling moulds for casting. The rate of pouring of hot metal and the take up rate of hot metal by the pig casting machine are equalized by adjusting the rate of tilting of the ladle and the speed of the conveyor chain of the pig casting machine strand.
Pig iron – It is the high-carbon iron made by reduction of iron ore in the blast furnace. It is the cast iron in the form of pigs. It is a high Fe (iron), low residual metallic material which is used for the production of high-quality iron and steel products in a wide variety of furnaces engaged in steelmaking and foundries. The material is not a scrap substitute but rather as a source of clean iron units which can be used to supplement and enhance the scrap charge. Pig iron is an intermediate product and the first product of ironmaking produced during the smelting of iron ore. It is produced when liquid iron (hot metal) is cast in the pig moulds. Pig iron is basically an alloy of iron (Fe), carbon (C), silicon (Si), and manganese (Mn). It also contains some percentage of sulphur (S) and phosphorus (P) as impurity elements, along with some titanium (Ti) and other trace elements. The C content of pig iron is high, typically in the range of 3.5 % to 4.5 %. With its defined and closely controlled specification and the absence of metallic impurities, pig iron is a reliable and consistent charge material for both the electric steelmaking as well as the ferrous castings production. The various grades of pig iron have specific chemical properties designed for their end use. The pig iron also contains valuable alloying elements and reduces the energy consumption of a melt.
Pig Iron, basic – Basic grade of pig iron has less than 1.0 % of silicon, and lower than 1 % of manganese. This type of pig iron is mainly used for steel making. There are several grades specified in different standards based on silicon and manganese content of the pig iron.
Pig Iron, foundry – Foundry grade of pig iron is mostly being used in iron foundries for remelting and casting into cast iron products. It contains higher quantity of silicon. Different standards specify composition limits for silicon and manganese for different grades of this type of pig iron. Silicon content in foundry grade pig iron is much higher and normally it is in the range of 1.5 % to 3.5 %. It can be as high as 4.25 %.
Pig Iron, nickel – Nickel (Ni) pig iron is a ferro-nickel pig iron containing 3 % to 13 % of Ni. It is a low grade ferro-nickel invented in China as a cheaper alternative to pure nickel for the production of stainless steel. The alternative has been developed as a response to high price of pure nickel. It contains much less nickel than the conventional ferro-nickel (25 % to 40 % Ni) and has higher concentrations sulphur and phosphorus. Nickel pig iron is presently being used to produce 200 series stainless steels, with limited application to the 300 series. There is considerable upside potential for nickel pig iron to be used more widely in the production of 300 series stainless steels with improvements in technology. The production process of nickel pig iron utilizes laterite Ni ores instead of pure Ni.
Pig launchers and receivers – These are specialized components in pipeline systems designed for the controlled introduction and removal of ‘pigs’ (pipeline inspection gauges). Launchers initiate the pig’s journey through the pipeline, while receivers retrieve it at the end, frequently after cleaning, inspection, or product separation tasks.
Pigment – It consists of small particles which are added to the paint to influence properties such as colour, corrosion resistance, and mechanical strength.
Pig moulds – These moulds are engineered to shape hot metal (liquid iron) into specific forms, allowing for efficient cooling and solidification. They have different sizes and shapes. These moulds are anchored to the chain of the pig casting machine. The pig mould has cavities for dividing the castings into 3 or 4 parts. It is designed with varying section thickness to maintain optimum heat transfer during the casting campaign. Two numbers of support brackets are provided in a mould at opposite ends for anchoring the mould to the chain of pig casting machine. The support brackets are kept tilted to match the inclination of pig casting machine strand so that the mould surface remains horizontal. The moulds anchored to the pig casting machine chain forms the train. The moulds are operational consumable for pig casting machine. The life of the mould depends upon the consistency and uniform filling of mould during casting campaign. For preventing sticking of pig iron to the moulds, the moulds are coated with lime powder.
PILC cables – PILC stands for ‘paper insulated lead cover’. For several years, the superior insulation material for power cables from low voltage to high voltages was oil-impregnated paper with lead sheath. Oil-impregnated paper has very good electrical properties and a high degree of thermal overload capacity without excessive deterioration. However, PILC cables have some disadvantages namely (i) they are prone to moisture and damage, (ii) they have low current carrying capacities, (iii) they need low operating temperatures, (iv) they have heavier weight and they are difficult to handle during installation, and (v) there is migration of impregnating compound which do not permit laying cables vertically or on steep slopes. Because of these disadvantages, the use of PILC cables is limited.
Pile – It is relatively long and slender member which is used to transmit the load to deeper soil or rock of high bearing capacity avoiding shallow soil of low bearing capacity. The main types of materials used for piles are wood, steel, and concrete. Piles made from these materials are driven, drilled, or jacked into the ground and connected to pile caps. Depending upon type of soil, pile material and load transmitting characteristic, piles are classified accordingly. Piles are also sometimes used to resist heavy uplift and lateral forces. Piles are normally used for (i) to carry structure loads into or through a soil stratum, (ii) to resist uplift or overturning forces, (iii) to control settlements when spread footings are on marginal or highly compressible soil, (iv) to control scour problems on bridge abutments or piers, (v) in offshore construction to transmit loads through the water and into the underlying soil, and (vi) to control earth movements, such as land-slides.
Pile butt – Pile butt is a member of the pile crew other than the operator and oiler.
Pile cap – It is a thick concrete mat which rests on concrete or timber piles that have been driven into soft or unstable ground to provide a suitable stable foundation. It normally forms part of the deep foundation of a building, typically a multi-story building, structure or support base for heavy equipment, or of a bridge. The cast concrete pile cap distributes the load of the building into the piles. A similar structure to a pile cap is a ‘raft’, which is a concrete foundation floor resting directly onto soft soil which can be liable to subsidence.
Pile driving – It is the operation of forcing a pile into the ground thereby displacing the soil mass across the whole cross section of the pile. Historically, the oldest method of driving a pile, and the method most frequently used today, is by use of an impact type hammer.
Pile foundation – It is defined as a series of columns inserted into the ground to transmit loads to a lower level of sub-soil. A pile is a long cylinder made up of a strong material, such as concrete. Piles are pushed into the ground to act as a steady support for structures built on top of them. Piles transfer the loads from structures to hard strata, rocks, or soil with high bearing capacity. The pile plays an important role as a key component in moving the base load through low-bearing soil strata to strata or rocks with high bearing capacity. In normal soil conditions, pile foundations are used to withstand elevations such as offshore platforms, foundations below groundwater levels, or basic transmission towers. Pile foundations are also used in soft soil to withstand horizontal loads, such as wind power and earth-quake bending forces. Soils which are easy to grow and shrink and which are sensitive to soil moisture change also need a pile foundation. In addition, construction works on water such as jetty and bridge piers, it also needs a pile foundation.
Pile gate – It is a hinged section attached to the pile leads, at the lower end, which acts to keep the pile within the framework of the pile leads.
Pile hammer – It is the unit which develops the energy used to drive piles, the two main parts of which are the ram and the anvil.
Pile monkey – It is a device used to position the pile in the leads beneath the hammer.
Pile rig – It is the crane used to support the leads and pile driving assembly during the driving operation.
Pile splice – It joins two segments of a driven pile, using either a weld (typical for H beams), grout or mechanical means (typical for precast concrete piles). Pile splices enable the use of shorter segments, which allows for driving piles in low-headroom situations such as under bridges or inside buildings. Reducing length of pile segments to under around 20 meters long also means the trailers which haul them to job sites can stay within state length limits.
Pile storage – Bulk ores and coals are frequently stored in open storage piles. A number of different methods and types of equipments are used for handling these plied materials. The main types of equipments used in the open pile storage are (i) stacking equipment, (ii) reclaiming equipment, and (iii) belt conveyors. Materials which are not weathered easily and need to be stored and reclaimed at substantial high hourly rate are kept in the open pile storage. The piles can contain materials from 5,000 tons to some million tons, while handling rate can vary from 100 tons per hour to 2,000 tons per hour. The capacity of the open pile storage normally ranges from 7 days to 45 days requirement of the consuming unit of the plant. Such wide variation of pile size and handling rate has influence on the selection of type and size of materials handling plant and equipments needed. The two basic open pile storage layouts are (i) longitudinal pile arrangement, and (ii) circular pile arrangement. The longitudinal arrangement allows easy future expansion but needs more space. The circular arrangement prevents any future expansion but has a more compact storage area. Longitudinal pile arrangement is used for high storage capacity. 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. These methods are cone shell method, chevron method, window method, and strata method.
Pile storage layout – It is a documented plan, typically a floor plan, which shows how materials are arranged in a pile storage facility, especially when exceeding a specific height threshold (e.g., 4 meters) set by fire codes. It details the location, dimensions, and height of the high-piled storage areas, the type of commodities stored, and the crucial clearance between the top of the storage and sprinkler deflectors to ensure dust suppression.
Pilger tube-reducing process – It is a process of reducing both the diameter and wall thickness of tubing with a mandrel and a pair of rolls.
Piling (sheet piling) – It is a structural steel product with edges designed to interlock. It is used in the construction of cofferdams or riverbank reinforcement. Sheet piling is differentiated according to its cross-sectional shape or its application such as (i) ‘S’, ‘U’, ‘Z’ and omega sheet piling, (ii) flat sheet piling, (iii) fabricated sheet piling (built up from sheet piles, angles and other sections), (iv) lightweight sheet piling (trench sheeting), (v) interlocking ‘H’ sheet piling, and (vi) box and tubular sheet piling.
Piling pipe – It is welded or seamless pipe for use as piles, with the cylinder section acting as a permanent load carrying member or as a shell to form cast-in-place concrete piles. There are normally three grades, which have different minimum tensile strengths, a variety of diameters, ranging from 150 millimeters to 750 millimeters, and a variety of wall thicknesses. Ends can be plain or beveled for welding.
Pillar – It is a block of solid ore or other rock left in place to structurally support the shaft, walls or roof of a mine.
Pillar extraction – It is also known as depillaring or pillar robbing It is a secondary underground mining technique where coal or ore is removed from the pillars which have been left standing during the primary development of a mine, such as a bord-and-pillar operation. The process involves removing material from these pillars and allowing the overburden (the overlying rock and earth) to collapse into the resulting void (goaf), which is a hazardous but necessary part of reclaiming resources and leaving the mine panel.
Pillar reinforcement – It is the process of strengthening structural pillars (columns) to improve their structural integrity and load-bearing capacity, typically by incorporating materials like steel bars or composites into the pillar. This is crucial in construction for handling heavy loads, preventing structural failure from forces like earthquakes or wind, and increasing the overall durability and safety of buildings and other structures.
Pillow block – A pillow block normally refers to a light duty housing, frequently in one piece and frequently with an integral anti-friction bearing.
Pillow block bearing – It is a mounting used to support a rotating shaft, using a bearing in a housing which is bolted to a foundation with the mounted shaft in a parallel plane to the mounting surface and perpendicular to the center line of the mounting holes, as contrasted with various types of flange blocks or flange units.
Pilot arc (plasma arc welding) – It is a low current continuous arc between the electrode and the constricting nozzle to ionize the gas and facilitate the start of the welding arc.
Pilot burner – It is a small, auxiliary burner which provides a continuous or intermittent flame to ignite a larger main burner in gas appliances like furnaces, stoves, or water heaters. It is essentially a small, stable flame which acts as a reliable ignition source for the main burner, ensuring consistent and safe operation.
Pilot casting – It is also called sample casting. It is a casting made from a pattern produced in a production die to check the accuracy of dimensions and quality of castings which is going to be made in quantity.
Pilot design – It refers to the structured plan for conducting a preliminary, small-scale trial of a new idea, process, or product to test its feasibility, identify potential problems, and gather data for a larger, full-scale implementation. The goal is to learn how to design and build the final solution successfully by assessing performance targets, refining methods, and establishing clear success criteria before substantial investment is made.
Pilot flame – It is a flame which is utilized to ignite the fuel at the main burner or burners.
Pilot fuel – It is a small quantity of combustible liquid injected into an engine’s combustion chamber to initiate or improve the ignition of a primary gaseous fuel, like natural gas, during dual-fuel engine operation. This pilot fuel creates a high-temperature zone, shortening the ignition delay of the main fuel and improving combustion performance, especially under low-load conditions where the primary gaseous fuel does not auto-ignite effectively on its own.
Pilot light -It is a small gas flame, normally natural gas or liquefied petroleum gas, which serves as an ignition source for a more powerful gas burner. Originally a pilot light was kept permanently alight, but this wastes gas. Now it is more common to light a burner electrically, but gas pilot lights are still used when a high energy ignition source is necessary, as in when lighting a large burner.
Pilot-operated relief valves (PORV) – These valves are also called pilot-operated safety valve (POSV), pilot-operated pressure relief valve (POPRV), or pilot-operated safety relief valve (POSRV). Like other pressure relief valves (PRV), pilot-operated relief valves are used for emergency relief during over-pressure events (e.g., a tank gets too hot and the expanding fluid increases the pressure to dangerous levels). Technically, pilot-operated pressure relief valve is the most generic term, but pilot-operated relief valve is frequently used generically even though it refers to valves in liquid service. In conventional pressure relief valves, the valve is normally held closed by a spring or similar mechanism that presses a disk or piston on a seat, which is forced open if the pressure is higher than the mechanical value of the spring. In the pilot-operated relief valve, the valve is held shut by piping a small amount of the fluid to the rear of the sealing disk, with the pressure balanced on either side. A separate actuator on the piping releases pressure in the line if it crosses a threshold. This releases the pressure on the back of the seal, causing the valve to open. The essential parts of a pilot-operated relief valve are a pilot valve (or control pilot), a main valve, a pilot tube, the dome, a disc or piston, and a seat. The volume above the piston is called the dome.
Pilot plant – It is a scaled-down, intermediate-sized facility used to test and refine new processes or products before investing in large-scale commercial production. It acts as a bridge between laboratory research and full-scale manufacturing, helping to identify and resolve potential issues and optimize designs before substantial resources are committed. A pilot plant is essentially a smaller version of a planned or existing full-scale production plant.
Pilot plant scale-up – It is the process of transitioning a laboratory-scale process or formulation to a larger, pre-commercial scale, aiming to refine the process for efficient and reproducible manufacturing before full-scale production. It involves optimizing production parameters, equipment, and procedures to ensure consistent quality and yield at a larger scale.
Pilot project – It is a small-scale, preliminary trial of a project or idea designed to test its feasibility, effectiveness, and potential challenges before full-scale implementation. It is a way to assess if a new concept or approach is viable and to gather valuable data for improvements before committing to a larger, more resource-intensive project.
Pilot signal – It is a dedicated signal transmitted over a communications system for different control and coordination purposes, serving as a reference point to improve system performance.
Pilot survey – It consists of a study, normally on a minor scale, carried out prior to the main survey, primarily to gain information about the appropriateness of the survey instrument, and to improve the efficiency of the main survey. Pilot surveys are an important step in the survey process, specifically for removing unintentional survey question biases, clarifying ambiguous questions, and for identifying gaps and / or inconsistencies in the survey instrument.
Pilot valve – It is a small, low-flow valve which controls the operation of a larger, main valve. It uses a fluid (like air, gas, or liquid) to activate the main valve, allowing a small input to control a high-pressure or high-flow system efficiently and remotely. Pilot valves are used to provide precision control, improve safety in hazardous environments, and allow for automation in industrial processes.
Pimples – These are small lumpy inclusions which can sometimes occur in galvanized coatings, caused by dross stirred up from the bottom of the galvanizing pot.
Pin – It is a machine element which secures the position of two or more parts of a machine relative to each other. A large variety of types has been known for a long time; the most commonly used are solid cylindrical pins, solid tapered pins, groove pins, slotted spring pins and spirally coiled spring pins.
Pincer – It is a tool made of two pieces of metal with blunt concave jaws which are arranged like the blades of scissors, used for gripping and pulling things. Pincers are a hand tool used in many situations where a mechanical advantage is required to pinch, cut or pull an object. Pincers are first-class levers, but differ from pliers in that the concentration of force is either to a point, or to an edge perpendicular to the length of the tool. This allows pincers to be brought close to a surface, which is frequently needed when working with nails.
Pinchers – It is the surface disturbances on metal sheet or strip which result from rolling processes and which ordinarily appear as fernlike ripples running diagonally to the direction of rolling.
Pinch marks – These are elongated markings, normally running with the grain and resulting from a folding-over of the metal during rolling. Such folds occur at the entry side of the rolling mill and are consequently rolled over and smoothed out in the subsequent rolling. It also consists of a sharp deviation from flat in the sheet which is transferred from processing equipment subsequent to the roll bite.
Pinch pass – It is a pass of sheet metal through rolls to affect a very small reduction in thickness.
Pinch rolls – The function of pinch roll in rolling mills is to drive the bar through dividing shear after it leaves the finishing stand. These are used one each for crop and cobble shears. The pinch rolls assemblies rotate in chocks housed in fabricated frames and are driven through D C Motors through gear box and the Cardan shafts. The roll size varies depending upon the requirement of the mill. The top roll is normally raised pneumatically or lowered with bottom roll in the adjustable to pass-line. The pinch roll housing has sturdy welded construction, which feature wear resistant surface with anti-friction bearing mounting support and the use of sensors that allows precision breaking up to the speed of hot bar material.
Pinch trimming – It is the trimming of the edge of a tubular metal part or shell by pushing or pinching the flange or lip over the cutting edge of a stationary punch or over the cutting edge of a draw punch.
Pinch valves – These valves are mainly used in order to regulate the flow of slurries in certain processes and systems. Pinch valves have flexible bodies which can be shut by pinching them. These valves are frequently used when it is necessary for the slurry to pass straight through when the valve is not pinched. Pinch valves can be controlled mechanically or with fluid pressure.
Pin connector – It is a component or assembly consisting of one or more electrical contacts in the form of pins, used to connect and transmit signals or power between two or more electronic devices or components. Pin connectors are characterized by the presence of physical pins, frequently in a row or matrix, which insert into corresponding sockets or contacts on another device to complete a circuit or connection.
Pin-cushion distortion – It is the distortion in the image which results when the magnification in the centre of the field is less than that at the edge of the field. It is also termed positive distortion.
PIN diode – It is a multilayer semi-conductor diode with a thin region of intrinsic material between its p-doped and n-doped regions.
Pin expansion test – It is a test for determining the ability of a tube to be expanded or for revealing the presence of cracks or other longitudinal weaknesses, made by forcing a tapered pin into the open end of the tube.
Pin (for bend testing) – It is the plunger or tool used in making semi-guided, guided, or wrap-around bend tests to apply the bending force to the inside surface of the bend. In free bends or semi-guided bends to an angle of 180-degree, a shim or block of the proper thickness can be placed between the legs of the sample as bending is completed. This shim or block is also referred to as a pin or mandrel.
Pinhole – It is small hole left in a weld area which allows low viscosity liquids to enter and become pressurized under the high temperature conditions of the molten zinc bath. It also consists of small cavities that penetrate the surface of a cured part.
Pin-hole porosity – It is the porosity consisting of several small gas holes (pin-holes) distributed throughout the metal. It is found in weld metal, castings, and electro-deposited metal.
Pinion – It is a round gear normally the smaller of two meshed gears which is used in several applications, including drive train and rack and pinion systems.
Pinion shaft – It is a mechanical component that transfers rotational motion and torque. It’s a round rod with teeth that mesh with a larger gear. Pinion shafts are used in several mechanical systems which include industrial equipment and machinery.
Pin joint – It is a mechanical connection between two parts which allows them to rotate relative to each other around a single axis, like a door hinge, while preventing any translation or rotation about other axes. It is a one-degree-of-freedom kinematic pair, also known as a revolute joint or pivot point, and is constructed by inserting a pin through aligned holes in the connected parts. Pin joints are used in mechanisms such as linkages and are a fundamental concept in the analysis of trusses and other structures.
Pin mill – It is a type of size reduction equipment, specifically a mechanical mill, which grinds materials by impact and attrition. It consists of rotating disks with pins, which collide with the material being processed, reducing its particle size. Pin mills are known for their ability to produce a narrow particle size distribution and are used in several industries for grinding, de-agglomeration, and homogenization. In pin mills, material is reduced in size through repeated collisions with the pins on the rotating disks and through attrition between the pins.
Pin mixer – It is a horizontal, medium-shear industrial mixer used in a wide variety of settings. It is well known for its ability to densify and de-dust, from chemical processing to energy production. It is the equipment of choice when pelletizing or agglomerating ultra-fine materials. A diverse machine, the pin mixer can be used as a stand-alone agglomeration device, or as part of a larger agglomeration process, where it preconditions material for downstream processing. The pin mixer is a key piece of equipment in the several applications including, de-dusting of coal, micro-pelletizing of specialty chemicals, and limestone and gypsum soil amendment production. Because of substantial flexibility, pin mixers are very effective when they are designed around the characteristics of the material to be processed.
Pinned dislocation – It is a dislocation which has been prevented from moving by an obstacle or impurity cluster. This makes the material harder and stronger.
Pinning – It refers to the phenomenon where local chemical and / or geometrical defects on a surface modify the contact angle, preventing a droplet from moving even when capillary or electro-capillary forces are applied.
Pinning points – In a crystalline material, a dislocation is capable of traveling throughout the lattice when relatively small stresses are applied. This movement of dislocations results in the material plastically deforming. Pinning points in the material act to halt a dislocation’s movement, needing a higher quantity of force to be applied to overcome the barrier. This results in an overall strengthening of materials.
Pin-on-disk machine – It is a tribometer in which one or more relatively moving styli (i.e., the ‘pin’ sample) is loaded against a flat disk sample surface such that the direction of loading is parallel to the axis of rotation of either the disk or the pin-holding shaft, and a circular wear path is described by the pin motion. The typical pin-on-disk arrangement resembles that of a traditional phonograph. Either the disk rotates or the pin sample holder rotates so as to produce a circular path on the disk surface. An arrangement wherein the pin sample is loaded against the curved circumferential surface of a flat disk is not normally considered to be a pin-on-disk machine.
Pin-on-disk tests – These tests are preferably used to determine two-body sliding wear. In pin-on-disk, the pin is attached with the polymeric material which is slid against the metallic disk or the metallic pin is slid against the disk made of polymer material.
Pin on disk tribometer – It is a type of wear testing machine which measures friction and wear between a stationary pin or ball and a rotating disk. It is a widely used apparatus in tribology (the study of friction, wear, and lubrication) for evaluating the performance of materials, coatings, and lubricants under controlled conditions. The machine applies a normal load to the pin, pressing it against the rotating disk, and measures parameters like friction force, wear rate, and temperature during the test.
Pins, flask – These are hardened steel locating pins used on flasks to ensure proper register of cope and drag moulds.
Pin shear test – It consists of any of several tests to get shear strength of a metal. These common tests which are used on mill products include the double-shear test, single-shear test, the blanking shear test (also known as the punching shear test) and the torsion test.
Piobert lines – These lines are also called Luders lines. These are elongated surface markings or depressions in sheet metal, frequently visible with the unaided eye, caused by discontinuous (inhomogeneous) yielding’.
Pipe – It is the central cavity formed by contraction in metal, especially ingots, during its solidification. It is also an imperfection in wrought or cast products resulting from such a cavity. It is a cast or wrought tubular product of metal or other materials.
Pipe anchor – It is a rigid pipe support designed to restrict all movement and rotation of a pipe, fixing it firmly to a supporting structure. It is used to manage forces such as thermal expansion, contraction, vibration, and external pressures, ensuring the pipe’s stability and protecting surrounding equipment and structures from stress, damage, and unwanted movement.
Pipe bend drawing – It establishes, by pictorial or tabular description or a combination thereof, end product definition for a single, multi-plane, pipe or pipe assembly along with the identification for the bent pipe or pipe assembly. It is prepared to specify complete requirements and configuration of rigid or semi-rigid piping for direct use in forming on a draw bending machine. It is prepared as a detail, assembly, or detail assembly drawing. It includes (i) pipe material, (ii) end types, (iii) identification and quantity of fittings, (iv) dimensional requirements including bend radii, angles, intersection points, intermediate and overall lengths, and (v) other data necessary to define design requirements.
Pipe bore – It refers to the internal diameter of the pipe. It is the diameter of the hollow space inside the pipe. The term is used to specify the approximate, or nominal, internal diameter for standard pipe sizes, which is important for determining flow rate and other performance characteristics.
Pipe classes – Pipe class is a document which specifies the type of the components such as a type of pipe, schedule, material, flange ratings, branch types, valve types and valve trim material, gasket, and all the other components specific requirements to be used for different fluids under different operating conditions in a plant. Pipe class is developed considering operating pressure, operating temperature, and corrosive environment. Piping specifications are technical documents which are generated by organizations for addressing additional requirements applicable to a specific product or application. These specifications provide specific / additional requirements for the materials, components, or services which are beyond requirements specified in standards and codes.
Pipe conveyor belt – It is a closed conveyor belt for tight curves and for protection of the environment.
Pipe defect – In case of forging of ingot, if there has been insufficient discard from the original ingot, remnant primary pipe normally shows up axially. Secondary pipe which has never been exposed to the atmosphere gets welded-up if there is sufficient forging.
Piped natural gas (PNG) – It is a form of natural gas which is distributed through a network of under-ground pipelines directly to residential, commercial, and industrial consumers. It is a clean-burning fossil fuel composed primarily of methane and is considered a more environmentally friendly alternative to other conventional fuels.
Pipe, drawn – It is the pipe brought to the final dimensions by drawing through a die.
Pipe, extruded -It is a pipe formed by hot extruding.
Pipe fittings – They allow pipes to be joined or installed in the appropriate place and terminated or closed wherever necessary. They can be expensive, need time, and different materials and tools to install. They are an essential part of piping systems. There are thousands of specialized fittings manufactured. Each type of pipe or tube needs its own type of fitting, but usually all pipe fittings share some common features. The basic purpose of using pipe fittings in pipe systems is to connect the bores of two or more pipes or tubes. Pipe fittings are used in piping systems normally (i) to connect straight pipe or tubing sections, (ii) to adapt to different sizes or shapes, (iii) to branch or re-direct the piping system, (iv) if necessary to provide a jointing method if two dissimilar piping materials are used in the one system, and (v) for other purposes, such as regulating, measuring or changing the direction of the fluid flow or to connect up threaded pipe and equipment. They are also used to close or seal a pipe. Fittings for pipe and tubing are very frequently made from the same base material as the pipe or tubing being connected, e.g., stainless steel, steel, copper or plastic. However, any material which is allowed by code can be used, but is to be compatible with the other materials in the system, the fluids being transported, and the temperatures and pressures inside and outside of the system.
Pipe flange – It is a disc, collar or ring that attaches to pipe with the purpose of providing increased support for strength, blocking off a pipeline or implementing the attachment of more items.
Pipe forming dies – These are specialized tools used in metal forming to shape metal pipes into desired forms. They are typically part of a larger machine, such as a press brake, and consist of a punch (the male portion) and a cavity (the female portion). These dies can be designed for different operations like bending, curving, and creating specific shapes in pipes and tubes.
Pipe for nipples – It is standard weight, extra strong, or double extra strong welded or seamless pipe, produced for the manufacture of pipe nipples. Pipe for nipples is generally produced in random lengths with plain ends, in nominal sizes from 3 millimeters to 300 millimeters. Close outside diameter tolerances, sound welds, good threading properties, and surface cleanliness are necessary in the pipes used for nipples. Pipe for oil country tubular goods (OCTG) couplings is to be manufactured from seamless pipe. It is normally coated with oil or zinc and is well protected before dispatch.
Pipe heat exchanger – It is a mechanical device that transfers heat between two fluids (either liquid or gas) without them mixing. This is achieved by using a physical barrier, typically metal pipes, to create a boundary for thermal energy transfer, allowing one fluid to heat or cool the other as they flow past each other. Common types include double-pipe heat exchangers, which feature one pipe inside another, and shell-and-tube exchangers, where tubes are housed within a larger shell.
Pipe joint – It is the connection point where two or more sections of pipe are joined to create a continuous pipeline, ensuring a secure and leak-free path for fluids or gases to flow. These connections are necessary for constructing any pipeline, as pipes are typically manufactured in shorter lengths which are to be joined to achieve the necessary system length and provide structural integrity. Pipe joints are formed using different methods, such as threading, soldering, welding, flanging, and compression, with the specific type chosen based on the pipe material, the application’s pressure and temperature requirements, and the need for strength or flexibility.
Pipeline – It is a system of pipes for long-distance transportation of a liquid or gas, typically to a market area for consumption. Pipelines are used to transport materials between equipment. In general, pipelines can be classified in three categories depending on purpose. These categories are (i) gathering pipelines consisting of group of smaller interconnected pipelines forming complex networks, (ii) transportation pipelines consisting mainly of long pipes with large diameters, and (iii) distribution pipelines which are composed of several interconnected pipelines with small diameters.
Pipeline conveyor – Classification of pipeline conveyors is made on the basis of air pressure used. In low pressure system, the operating air pressure is normally limited to 0.1 megapascal gauge. This system is restricted to short distances (up to 500 meters) and small flow rate. This system is further sub-classified into (i) positive pressure system, (ii) negative pressure (or suction) systems, and (iii) combined negative-positive pressure (or combination) system. In medium pressure system the air pressure is in the range of 0.1 megapascal gauge to 0.3 megapascal gauge. In high pressure system the air pressure is in the range of 0.4 megapascal gauge to 0.7 megapascal gauge. Medium-pressure and high-pressure systems are essentially positive pressure type systems.
Pipeline engineering – It is a specialized field of engineering focused on the design, construction, operation, and maintenance of pipeline systems used to transport fluids like water, oil, gas, and chemicals over long distances. It encompasses a wide range of activities, including material selection, route planning, stress analysis, safety protocols, and leak detection. Core aspects of pipeline engineering include (i) design and planning which involves determining the optimal route, selecting appropriate materials (steel, plastic, etc.), and designing the pipeline’s dimensions to handle the needed flow rate and pressure, (ii0 construction stage which includes excavation, pipe laying, welding, coating, and testing to ensure the pipeline is built to the required standards and specifications, (iii) operation and maintenance which involves monitoring the pipeline’s performance, conducting regular inspections, and implementing maintenance procedures to prevent failures and ensure safe and efficient operation, and (iv) prioritization of safety and environmental protection which includes designing for leak detection, implementing emergency shut-off systems, and adhering to strict environmental regulations.
Pipeline leak detection – It is an engineering system and set of techniques used to identify the occurrence and location of leaks in pipelines which transport liquids and gases, enabling operators to respond quickly to minimize risks and prevent incidents like environmental damage or accidents. These systems utilize different technologies, such as pressure monitoring, fibre optics, and acoustic sensors, to detect changes in the pipeline’s condition, such as pressure drops or temperature fluctuations, which indicate a leak.
Pipeline network – Bedsides pipes, tubes, and hoses, it consists of several components which can be categorized into (i) equipments, (ii) pipelines, (iii) fittings, (iv) instruments, and (v) structures. Equipment is a component which provides power, process, and stores materials. Common equipments includes pumps, tanks, vessels, heat exchangers, and towers etc. The individual components necessary to complete a piping system are (i) pipe, (ii) piping flanges and fittings, (iii) valves, (iv) bolts and gaskets (fasteners and sealing), and (v) piping special items, such as steam traps, pipe supports, and valve interlocking etc. Pipes come in different materials and sizes, but steel pipes are the most popular type of pipes. Fittings are components attached to the pipelines and equipments. Pipelines can be of different pipe sizes. They provide means of changing flow directions and allow branches and connections. Fittings include connectors and joints. Instruments and field devices are auxiliary equipment and tools used to measure, monitor and control parameters of piping processes. Instruments include meters and gauges, indicators and recorders, control valves and actuators, and controllers. Meters and gauges are used to measure process variables like flow, temperature, and pressure etc., indicators and recorders are used to monitor process variables, valves and actuators are used to regulate the variables while controllers are used to make appropriate changes in variables for ensuring proper operating conditions and prevent hazards.
Pipe piles – These piles are made of steel pipes and are installed by driving pipes to the desired depth and filling them with concrete. These piles are provided with a driving point or shoe at the lower end. These piles are driven into the ground with their ends open or closed. A pipe can be driven with the lower end closed with a plate or a steel driving point, or the pipe can be driven with the lower end open. Pipes vary in diameter from 150 millimeters to 750 millimeters and the length can reach 60 meters. A closed-end pipe pile is driven in any conventional manner, normally with a pile hammer. If it is necessary to increase the length of a pile, two or more sections can be welded together. An open-end pipe pile is installed by driving the pipe to the needed depth, removing the material from inside, by burst of compressed air, a mixture of water and compressed air, and filling the space with concrete. Since the open-end pipe piles offer lesser driving resistances than closed-end piles, a smaller pile hammer can be used. Epoxy coatings are applied during the pipe manufacture for reducing the pipe corrosion. Sometimes concrete encasement at the construction site is done as a protection against corrosion. An additional thickness of the steel section is normally desired for taking into account the corrosion.
Pipe rack – It is an elevated, frame-like structure, typically made of steel or concrete, which supports and routes multiple pipes, cable trays, and sometimes mechanical equipment within a plant. These structures serve as the ‘main arteries’ of a process plant, connecting different pieces of equipment and facilitating the safe and organized transport of fluids, cables, and other materials while also allowing for thermal expansion of the pipes.
Pipe reactor – It is also called pipe cross reactor. It is an acid-base reaction vessel which can be integrated into a granulation drum for the production of some fertilizer products. Initially developed to produce ammoniated phosphate fertilizer, in the right setting, it can add substantial value to an operation. The pipe reactor has been shown to substantially reduce plant energy costs by utilizing the reaction heat as the primary method of drying, reducing the burden on the dryer.
Pipe rolling mills – These mills are used for the production of different types of pipes. Pipe mills can be for the production of welded pipes or for the production of seamless pipes. Welded steel pipes are produced with either a longitudinal seam or a spiral (helical) seam. The starting material for the production of the welded pipes is rolled flat product which depending on the pipe production process, pipe dimensions and application, can be hot rolled or cold rolled steel strip /skelp, and hot rolled wide strip or plate. This starting material can be formed into pipe shape in either hot or cold condition. The forming process can be either a continuous process or a single pipe forming process. In continuous pipe forming process, uncoiled strip material is taken from an accumulator, with the leading end and the trailing end of the consecutive coils being welded together. In single pipe forming process, the pipe forming and welding operation is carried out in single pipe length. There are two types of welding processes which are mainly used for the welded pipe production. These are (i) pressure welding processes, and (ii) fusion welding processes. The commonly used pressure welding processes are (i) pressure welding process e.g. Fretz-Moon process, (ii) direct current electric resistance welding, (iii) low frequency electric resistance welding, (iv) high frequency induction welding, and (v) high frequency conduction welding. The commonly used fusion welding processes are (i) submerged arc welding, and (ii) gas shielded welding. Seamless pipes are made from round billet, which is pierced through the centre to make it a hollow shell and then rolled or extruded and drawn to size. The seamless pipe manufacturing process consists of three stages namely (i) making of a hollow pipe shell in the piercing or extrusion operation, (ii) elongating the hollow pipe shell by reducing its diameter and wall thickness, and (iii) making of a final pipe in the hot or cold rolling process. As the manufacturing process does not include any welding, seamless pipe is perceived to be stronger and more reliable. Seamless pipe is regarded as withstanding pressure better than other types of pipes.
Pipes and tubes – This term is used to cover all hollow products. Although these products are normally produced in cylindrical form, they are frequently subsequently altered by various processing methods to produce square, oval, rectangular, and other symmetrical shapes. Such products have applications which are almost innumerable, but they are most commonly used as conveyors of fluids and as structural members. One of the major applications of the pipe is in the process and the metallurgical industries. The rolling mills for pipes are normally multi stand continuous mills. Pipe is normally produced to several long-standing and broadly applicable industrial standards. While similar standards exist for specific industry application tubing, tube is frequently made to custom sizes and a broader range of diameters and tolerances. Several industrial and government standards exist for the production of pipes and tubes. Tubes are frequently made to custom sizes and can often have a large number of specific sizes and tolerances than pipes. The term ‘tube’ is also normally applied to non-cylindrical sections (square or rectangular tube). Both pipes and tubes are associated with a level of rigidity and permanence while a hose is usually portable and flexible.
Pipe schedule – It is a standard which measures the nominal wall thickness of a pipe. The pipe schedule number is non-dimensional and depends on the nominal pipe size, internal pipe working pressure, and the material used for the pipe wall.
Pipe, seamless – It is the extruded or drawn pipe which does not contain any line junctures resulting from the method of manufacture.
Pipe sleeve – It is also called pipe casing. It is a protective outer pipe section or ring used to provide a pathway for, protect, or support an inner pipe. Common uses include creating openings in concrete structures, protecting pipes from damage during construction or heavy loads, offering support and movement for pipes, providing barriers against heat and fire, or even serving as a temporary repair on a leaking pipeline.
Pipe, structural – It is the pipe which is normally used for structural purposes.
Pipe tap – It is a tap for making internal pipe threads within pipe fittings or holes.
Pipe threads – These are internal or external machine threads, normally tapered, of a design intended for making pressure tight mechanical joints in piping systems.
Pipette – It is also spelled as pipet. It is a type of laboratory tool to transport a measured volume of liquid, frequently as a media dispenser. Pipettes come in several designs for different purposes with differing levels of accuracy and precision, from single piece glass pipettes to more complex adjustable or electronic pipettes. Several pipette types work by creating a partial vacuum above the liquid-holding chamber and selectively releasing this vacuum to draw up and dispense liquid. Measurement accuracy varies greatly depending on the instrument.
Piping – It is a system of pipes which is used to convey fluids (liquids and gases) from one location to another. In castings, piping is the defect encountered in risers or within the casting proper. In weld metal, blow holes are normally gas pores larger in dimension while piping is an elongated or tubular cavity. Piping is normally almost perpendicular to the weld surface. It can result from the use of wet powdered flux or from inadequate control of the welding current. Another typical form of pipes has the appearance of a branch of a tree.
Piping and instrument diagram – It is sometimes called process and instrument diagram. It is more technical, describing mechanical details for piping designers, electrical engineers, instrument engineers, and other technical experts who need this detail more than they need process details. Piping and instrument diagrams take the conceptual aspects of a process flow diagram and add detail about the equipment, process sequence, process and utility piping, bypass lines, instruments, valves, vents, drains and other items. Piping and instrument diagrams are the drawings showing piping and communications as schematic (unscaled) lines and control features as symbols. Piping and instrument diagrams show the functional relationship of piping, instrumentation, equipment, and controllers. They are normally a part of the instrumentation drawings in a project drawing set. Piping and instrument diagrams are normally made by process engineers, controls engineers, and electrical engineers. The main purpose of a piping and instrument diagram is to indicate if the equipments are automatically controlled, and if so, how they are inter-locked with instruments. Piping and instrument diagrams convey the inter-connectivity of automated equipments. Piping and instrument diagram is based on the process flow diagram and depicts the technical realization of a process by means of graphical symbols representing equipment and piping, together with graphical symbols for process measurement and control functions. All equipment, valves, and fittings are represented as per ISO 10628-2. The process measuring and control tasks are represented as per IEC 62424. Auxiliary systems can be represented by rectangular frames with references to separate flow diagrams.
Piping design – It is the engineering process of planning, designing, constructing, and maintaining piping systems, which are used to transport fluids (liquids, gases, solid powders, and slurries) within industrial facilities. It involves creating layouts, selecting materials, ensuring safety and compliance with codes, and collaborating with other engineering disciplines.
Piping design and pipeline engineering – It refers to the creation and documentation of industry standard layout for pipes, equipment, instruments, and controls. Application areas are plumbing, civil, process, and transportation.
Piping diagrams and drawings – Diagrams and drawings are graphic models of objects. Diagrams are refined sketches which are created without scale. However, good proportion is encouraged in diagrams since it improves aesthetics. Drawings are made to scale and hence bear direct relationship to the physical size and spatial orientation of the object represented. There are five types of piping diagrams which are normally used. These are (i) schematic or block flow diagrams (BFD), (ii) process flow diagrams (PFD), (iii) piping (process) and instrumentation diagram (P&ID), (iv) piping isometric diagram, and (iv) piping spool diagram.
Piping drawings – These are scaled graphic representations of piping systems and devices. They include plans (top views), elevations (frontal or profile views) and sections (internal frontal or profile views). Piping drawings can be very complex sometimes as they show all equipment, fittings, instrumentations, dimensions and notes. Data for piping drawings are derived from process flow diagrams, structural, mechanical, instrumentation drawings, and catalogues / manuals of the suppliers. Piping drawings include (i) plot or site plan, (ii) unit plan, (iii) zone plan, (iv) equipment drawings, (v) equipment layout drawings, (vi) piping plans and elevations, and (vii) 3D (three dimensional) plant model.
Piping engineering – It is a discipline which focuses on designing, analyzing, and laying out piping systems. Piping systems are the circulatory pathways for fluids and gases in industrial facilities.
Piping isometric drawing – It is a pseudo-3D diagram of a single pipe run. All fittings and attachments on the pipe are shown.
Piping layout – It refers to the strategic arrangement and routing of pipes, along with associated components like valves, fittings, and instrumentation, within a facility. Piping layout drawing is developed in both plan view and elevation view and section / details are added for clarity wherever necessary. These drawings are called the ‘general arrangement’ (GA) of piping. For representing a three-plane piping in two dimensions of the paper, certain symbols as given in the national and international standards are followed. Orthographic symbols are available in templates which are used for speeding up the manual drafting and also in the symbol library for computer aided design (CAD). Piping layout is a crucial aspect of piping design, aiming to ensure efficient, safe, and reliable fluid or gas transportation while also considering factors like maintenance, cost, and regulatory compliance.
Piping spool drawings – These are detail section drawings of pipes and fittings used by pipe fitters and welders during construction. A spool diagram is a sub-section of a piping isometric drawing which can be assembled in a shop and shipped to the plant site.
Piping structures – They provide support to all the elements in a piping system and help hold them together. These include foundations, racks and sleepers, platforms, and ladders and different types of local supports and locators. Pipes need supports for rigidity, hence, hangers, clamps, saddles, and anchors etc. are used.
Pips, pip-lines, pip-marks, ident pips – It is a marking on an extrusion (on a non-visible surface) placed there by the extrusion mill’s die to allow the mill to identify extrusions produced by that mill.
Pirani gauge – It is an instrument used to measure the pressure inside a vacuum chamber. The gauge measures electrical resistance in a wire filament which changes in temperature depending on atmospheric pressure.
Piston – It is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft through a piston rod and / or connecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the fluid in the cylinder. In some engines, the piston also acts as a valve by covering and uncovering ports in the cylinder. In case of a valve, a piston is a rigid movable pressure responsive element which transmits force to the piston actuator stem.
Piston check valve – It is also known as a lift check valve. It is a type of check valve which uses a piston (or disc) to prevent backflow in a pipeline. It allows fluid to flow in one direction and automatically closes to prevent flow in the opposite direction. The piston is typically guided within the valve body to ensure proper alignment and sealing.
Piston compressor – It is also known as a reciprocating compressor. It is a type of air compressor which uses a piston moving back and forth within a cylinder to compress air. This reciprocating motion, driven by a crankshaft, creates alternating high and low-pressure areas, drawing in air and then compressing it. The compressed air is then stored in a tank for various applications. Piston compressors utilize the back-and-forth movement of a piston inside a cylinder to compress air. As the piston moves down, it creates a vacuum, drawing air into the cylinder through an intake valve. Then, as the piston moves up, it compresses the air, forcing it out through a discharge valve into a storage tank.
Piston displacement – It is the total volume an engine’s piston sweeps from its bottom-most to top-most position during a single stroke, representing the space cleared by the piston as it moves within a cylinder. This ‘engine displacement’ is a key factor in an engine’s size and power potential, with larger displacement indicating the capacity to draw in more air and fuel, normally leading to higher power. It is calculated by multiplying the piston’s swept volume by the total number of cylinders in the engine.
Piston-pin bearing – It is a bearing at the smaller (piston) end of a connecting rod in an engine.
Piston pin boss – It is a reinforced area on each side of a piston, designed to accommodate and support the piston pin (also known as a wrist pin). This pin connects the piston to the connecting rod, allowing the piston to move up and down within the cylinder.
Piston press – It is a mechanical press consisting of a ram (piston) and a die and it is driven by either by an electric or a hydraulic drive. The feedstock is punched into a die by a reciprocating ram with a very high compaction pressure to get a briquette. The achieved briquette densities are normally in the range between 1,000 kilograms per cubic meter to 1,200 kilograms per cubic meter.
Piston pump – It is a type of positive displacement pump where the high-pressure seal reciprocates with the piston. These pumps can be used to move liquids or compress gases. They can operate over a wide range of pressures. High pressure operation can be achieved without adversely affecting flow rate. These pumps can also deal with viscous media and media containing solid particles. This pump type functions through a piston cup, oscillation mechanism where down-strokes cause pressure differentials, filling of pump chambers, where up-stroke forces the pump fluid out for use. Piston pumps are frequently used in scenarios needing high, consistent pressure and in water irrigation or delivery systems. The two main types of piston pump are the lift pump and the force pump. Both types can be operated either by hand or by an engine.
Piston ring – It is a metallic split ring which is attached to the outer diameter of a piston in an internal combustion engine or steam engine. The main functions of piston rings in engines are (i) sealing the combustion chamber so that there is minimal loss of gases to the crank case, (ii) improving heat transfer from the piston to the cylinder wall, (iii) maintaining the proper quantity of the oil between the piston and the cylinder wall, and (iv) regulating engine oil consumption by scraping oil from the cylinder walls back to the sump. Majority of the piston rings are made from cast iron or steel.
Piston rod – It is the component which drives the piston to compress gas within a cylinder, typically attached to the piston by a single extension or multiple through-bolts, which help maintain uniform loading and adequate prestress levels.
Piston stroke – It is the linear distance the piston travels within a cylinder, from its uppermost point (top dead centre or TDC) to its lowermost point (bottom dead centre or BDC). This movement is a fundamental part of an engine’s operational cycle, defining the swept volume of the cylinder and crucial for processes like intake, compression, power, and exhaust.
Piston-type actuator – It is a fluid powered device in which the fluid, normally compressed air, acts upon a movable piston to provide motion of the actuator stem and provide seating force upon closure. Piston-type actuators are classified as either double-acting, so that full power can be developed in either direction, or as spring-fail so that upon loss of supply power, the actuator moves the valve in the needed direction of travel.
Piston valves – These valves have a closure member shaped like a piston. When the valve opens, no flow is observed until the piston is fully moved from the seat bore, and when the valve closes, the piston removes any solids which might be deposited on the seat. Hence, piston valves are used with fluids which have solid particles in suspension.
Pit – It is a small, regular or irregular crater in the surface of a material created by exposure to the environment, e.g., corrosion, wear, or thermal cycling. It is also a small, regular or irregular crater in the surface of a plastic, normally of a width approximately the same order of magnitude as its depth.
Pitch – It is a viscoelastic polymer which can be natural or manufactured, derived from petroleum, coal tar, or plants. Pitch produced from petroleum can be called bitumen or asphalt, while plant-derived pitch, a resin, is known as rosin in its solid form. In sound, the sensation of a frequency is normally referred to as the pitch of a sound. A high pitch sound corresponds to a high frequency sound wave and a low pitch sound corresponds to a low frequency sound wave. Pitch is a perceptual property which allows sounds to be ordered on a frequency-related scale, or more commonly, pitch is the quality that makes it possible to judge sounds as ‘higher’ and ‘lower’. Pitch can be quantified as a frequency. The sensation of a frequency is commonly referred to as the pitch of a sound. A high pitch sound corresponds to a high frequency sound wave and a low pitch sound corresponds to a low frequency sound wave. In case of screw gauge, pitch is defined as the linear distance covered by the screw in each rotation. In other words, it can be defined as the axial distance between the two threads of the main scale. In case of fasteners, it is the linear distance from a point on the thread to a corresponding point on the next thread which is measured parallel to the axis of the thread. Pitch in a conveying the distance between the centre points of adjacent components, necessitating periodic assessments to maintain proper pitch dimensions for optimal system performance. Pitches are used as base materials for the manufacture of certain high-modulus carbon fibres and as matrix precursors for carbon-carbon composites.
Pitch bearing basic ramming mix – It is a pitch bearing refractory which has suitable properties to permit ramming into place to form a monolithic structure.
Pitch bearing basic refractories – These are refractories consisting mainly of basic grains to which pitch has been added during manufacture.
Pitchblende – It is an important uranium ore mineral. It is black in colour, possesses a characteristic greasy lustre and is highly radioactive.
Pitch-bonded basic brick – It consists of unburned basic refractory shapes which are bonded with pitch. If subsequently heat-treated sufficiently to minimize softening of the bond on reheating, they are referred to as tempered.
Pitch-bonded basic ramming mix – It is a type of refractory material, specifically designed for furnace linings, that uses a basic aggregate (like magnesia or dolomite) bonded with pitch (a carbonaceous material). Upon heating, the pitch decomposes, leaving behind a carbon bond which provides strength and resistance to high temperatures, corrosion, and thermal shock. These mixes are used in different steelmaking processes, particularly in basic oxygen furnaces (BOF), where they form monolithic linings which can withstand the harsh conditions of steel production.
Pitch bonded basic refractories – These are a type of refractory material which are normally used in steelmaking and other high-temperature applications. These refractories utilize pitch as a binder to hold together basic oxide grains like magnesia (MgO) or dolomite (CaO.MgO). The pitch, which can be coal tar or petroleum-based, provides initial strength and a degree of slag resistance. During use, the pitch decomposes under heat, leaving behind a carbon matrix which further improves the refractory’s properties, particularly its resistance to slag penetration and thermal shock.
Pitch-bonded dolomite refractories – These are a type of refractory material used in steelmaking, particularly in the barrel region of secondary steelmaking ladles for silicon-killed steels. They are composed of burnt dolomite aggregate bonded with a carbonaceous material, normally pitch (either coal tar pitch or petroleum pitch), and frequently include a cure accelerator. These refractories are chosen for their compatibility with calcium-silicate slag and other techno-economic factors.
Pitch-bonded magnesite bricks – These are used in several applications, but mainly in basic oxygen furnaces and steel ladles. These bricks have excellent thermal shock resistance and high temperature strength, and good slag resistance. These bricks were the principal working lining materials for basic oxygen furnaces for many years. Although in severe service environments they have been replaced to a large extent by more erosion resistant graphite-containing magnesite- carbon brick, they continue to play an important role in, for example, lower wear areas of basic oxygen furnaces.
Pitch bonding – It is the use of pitch or tar to produce a bond in a pressed unfired refractory.
Pitch-based carbon fibre – It is a high-performance material made from pitch, a residue of carbon-based materials like petroleum or coal. This synthetic fibre is produced through melt extrusion, stabilization, and high-temperature carbonization processes, resulting in unique structures like isotropic (filler) or mesophase (reinforcing) types. Unlike Polyacrylonitrile-based carbon fibres, pitch-based fibers are known for achieving superior Young’s modulus (stiffness), low thermal expansion, and high thermal conductivity, making them ideal for demanding applications.
Pitch circle diameter (PCD) – It is the diameter of that imaginary circle which passes through the centre of all the bolt holes or wheel bolts or wheel rim holes or studs.
Pitch creosote mixture (PCM) – It is a black, semi-liquid substance produced during coal tar distillation, consisting of a blend of creosote oil and pitch. It is used industrially as a binder for making carbon bricks, and in the manufacturing of silicon carbide blocks, heating elements, crucibles, and ramming masses. The composition of PCM includes polycyclic aromatic hydrocarbons (PAHs), which can have harmful health effects, requiring careful handling and appropriate safety measures.
Pitch diameter – It is, also known as the effective diameter. It is the imaginary half way point of the thread form and is based completely on thread features, the thread groove i.e., minor diameter and the thread crest i.e., major diameter.
Pitch drop experiment – It is a long-term experiment which measures the flow of a piece of pitch over many years. ‘Pitch’ is the name for any of a number of highly viscous liquids which appear solid, most commonly bitumen, also known as asphalt. At room temperature, tar pitch flows at a very low rate, taking several years to form a single drop.
Pitch error – It is the difference between the actual pitch and the nominal pitch on the gear reference circle.
Pitch impregnation – It is the use of liquid pitch or tar to impregnate a refractory after forming or firing.
Pitch-impregnated basic brick – It consists of burned basic refractory shapes impregnated with pitch after firing.
Pitch ratio – It is a dimensionless quantity defined as the ratio of the pitch of a propeller or gear to its diameter, with a nominal pitch frequently quoted at a specific radius (typically 70 % of the maximum) for propellers. It indicates the theoretical forward distance a rotating blade or gear tooth moves in one revolution, adjusted by the diameter of the device.
Pit mould – It is a mould in which the lower portions are made in a suitable pit or excavation in a foundry floor.
Pit moulding – It is a moulding method in which the drag is made in a pit or hole in the floor.
Pitot tube – It is an instrument which measures the stagnation pressure of a flowing fluid, consisting of an open tube pointing into the fluid and connected to a pressure-indicating device. It is also known as impact tube.
Pitted surfaces – These are the areas of steel where small, sharp cavities exist, normally formed by the corrosion.
Pitting – It is corrosion of a metal surface, confined to a point or small area, which takes the form of cavities. It is the forming small sharp cavities in a surface by corrosion, wear, or other mechanically assisted degradation. It is also localized corrosion of a metal surface, confined to a point or small area, which takes the form of cavities. In tribology, it is a type of wear characterized by the presence of small, sharp surface cavities formed by processes such as fatigue, local adhesion, wear, corrosion, or cavitation.
Pitting corrosion – It is the non-uniform corrosion of the surface which causes small pits or craters to develop. It is a localized form of corrosion which leads to the creation of small holes (pits) in the metal. This form of corrosion is mainly found on passive metals. Passive metals and alloys, such as aluminum, titanium and stainless steel owe their corrosion resistance to a thin oxide layer on the surface with a thickness of only a few nanometers. The corrosion initiating process starts with a local break-down of the passive layer. Local corrosive attack can be initiated on stainless steels, for example, by chloride ions. Pitting corrosion can be quite problematic. Whereas uniform corrosion can be seen clearly on the surface, pitting corrosion often appears only as small pinholes on the surface. The amount of material removed below the pinholes is generally unknown, as hidden cavities may form, making pitting corrosion more difficult to detect and predict. Technically, there is no reasonable way to control pitting corrosion. This form of corrosion is required to be excluded right from the start through proper designing and use of the right material. In addition, pitting corrosion can often be the starting point for more severe forms of corrosion such as stress corrosion cracking (SCC).
Pitting corrosion resistance – It is a material’s inherent ability to resist pitting corrosion, a highly aggressive and destructive form of localized corrosion where small holes or cavities form on a metal surface. Materials with high pitting resistance can withstand this type of attack, which frequently occurs in chloride-containing environments, and are characterized by higher pitting potential and critical pitting temperature.
Pitting factor – t is the ratio of the depth of the deepest pit resulting from corrosion divided by the average penetration as calculated from weight loss.
Pitting resistance equivalent numbers (PREN) – These are a theoretical way of comparing the pitting corrosion resistance of different types of stainless steels, based on their chemical compositions. Pitting resistance equivalent numbers are useful for ranking and comparing the different grades, but cannot be used to predict whether a particular grade will be suitable for a given application, where pitting corrosion may be a hazard. These are linear formulas, where the molybdenum and nitrogen levels are weighted to take account of their strong influence on pitting corrosion resistance. They typically take the form PREN = Cr + mMo + nN, where ‘m’ and ‘n’ are the factors for molybdenum and nitrogen.
Pivot – It is the point of rotation in a lever system. More generally, it is the centre point of any rotational system.
Pivot bearing – It is an axial-load, radial-load type bearing which supports the end of a rotating shaft or pivot.
Pivoted-pad bearing – It is a pad bearing in which the pads are free to take up a position at an angle to the opposing surface as per the hydrodynamic pressure distribution over its surface.
Pivot plate – It is the gusset which attaches the conveyor to the support leg.
Pivot point – It is the specific point, axis, or location around which an object rotates or oscillates. This point acts as a fixed centre for rotational motion, allowing forces applied at a distance to create a torque, causing the object to turn. It is a fundamental concept in mechanical systems, visible in levers, robotic arms, and the turning of large vessels.
piw – It means pounds per inch of width. It is a term used in some countries, indicating a belt’s working tension.
Pixel – It is also called picture element. In digital imaging, a pixel is the smallest addressable element in a raster image, or the smallest addressable element in a dot matrix display device. In majority of the digital display devices, pixels are the smallest element which can be manipulated through software. Each pixel is a sample of an original image. More samples typically provide more accurate representations of the original. The intensity of each pixel is variable. In colour imaging systems, a colour is typically represented by three or four component intensities such as red, green, and blue, or cyan, magenta, yellow, and black.
Placer – It is a deposit of sand and gravel containing valuable metals such as gold, tin, or diamonds.
Plain bearing – It is the simplest type of bearing, comprising just a bearing surface and no rolling elements. Hence, the part of the shaft in contact with the bearing slides over the bearing surface. The simplest example of a plain bearing is a shaft rotating in a hole. A simple linear bearing can be a pair of flat surfaces designed to allow motion, e.g., a drawer and the slides it rests on or the ways on the bed of a lathe. Plain bearings, in general, are the least expensive type of bearing. They are also compact and lightweight, and they have a high load-carrying capacity.
Plain carbon steel – It is steel where the main alloying constituent is carbon. Steel is considered to be plain carbon steel where minimum content is not specified or required for chromium, cobalt, molybdenum, niobium, nickel, tungsten, vanadium, or zirconium, or any other element to be added to get a desired alloying effect or when the specified minimum for copper does not exceed 0.40 % or when the maximum content specified for manganese and silicon does not exceed 1.65 % and 0.60 % respectively. The plain carbon steels are classified based on carbon percentage as (i) ultra low carbon steels which contain very low carbon normally less than 0.005 %, (ii) low carbon steels which contain carbon from 0.005 % up to 0.1 %, (iii) mild steels which contain carbon from 0.1 % up to around 0.3 %, medium carbon steels which contain carbon from 0.35 % to 0.6 %, (iv) high carbon steels which contain carbon from 0.61 % to 1 %, and (v) ultra high carbon steels which contain carbon from 1 % to 1.2 %. Ultra high carbon steels are made by powder metallurgy technique.
Plain journal bearing – It is a plain bearing in which the relatively sliding surfaces are cylindrical and in which there is relative angular motion. One surface is normally stationary and the force acts perpendicularly to the axis of rotation.
Plain thrust bearing – It is a plain bearing of the axial-load type, with or without grooves.
Plain weave – It is a weaving pattern in which the warp and fill fibres alternate, i.e., the repeat pattern is warp / fill / warp / fill, and so on. Both faces of a plain weave are identical. Properties are considerably reduced relative to a weaving pattern with fewer crossovers.
Plan – It consists of a list of steps with details of timing and resources, used to achieve an objective to do something. It is normally understood as a set of intended actions through which one expects to achieve a goal. Plans can be formal or informal. Structured and formal plans, used by multiple people, are more likely to occur in projects, or organizations, or in the conduct of an activity. In most cases, the absence of a well-laid plan can have adverse effects. Informal or ad hoc plans are created by people in all of their pursuits. Plan is also a graphical depiction of characteristics on or under the earth’s surface as portrayed in a horizontal position. Plan is also the overall design of a building. In addition to the design, it offers notes with detailed specifications regarding important components to the plan such as materials which are to be used, area calculations, and more.
Planar – It is a microstructure-related defect. Planar consists of stacking faults, solid–vapour interface, grain and phase boundaries. Because of this defective structure, there is inability of steel to achieve a desired microstructure and hence required microstructure related property during thermo mechanical processing. Planar also means lying essentially in a single plane.
Planar anisotropy – It is a variation in physical and / or mechanical properties with respect to direction within the plane of material in sheet form.
Planar defects – These are two-dimensional imperfections or irregularities which occur within the crystal structure, specifically along a plane. These defects are characterized by their extension in two dimensions (length and width) while having a relatively small thickness. Common examples of planar defects include grain boundaries, stacking faults, and twin boundaries. Planar defects are essentially interfaces or boundaries between regions of different crystal orientations or stacking sequences within a material. They are two-dimensional since they extend over a plane while having a limited thickness.
Planar graph – In network theory, it is a set of nodes and interconnecting lines which can be given in one plane without crossing lines.
Planar helix winding -It is a winding in which the filament path on each dome lies on a plane which intersects the dome, while a helical path over the cylindrical section is connected to the dome paths.
Planar kinematics – It is the study of the motion of rigid bodies confined to a two-dimensional plane, describing their position, velocity, and acceleration without considering the forces which cause the motion. It involves analyzing different types of planar motion, including rectilinear translation, curvilinear translation, and rotation about a fixed axis, as well as the general plane motion that combines these types.
Planar magnetron – It is a device which used in the sputtering of thin films, in which a magnet system on the back of the cathode deflects the electrons, lengthening the ionization path. The accelerated ions transfer their momentum to particles of the coating material, which are then deposited on the substrate.
Planar winding – It is a winding in which the filament path lies on a plane which intersects the winding surface.
Planck’s constant (h) – It is a fundamental physical constant, the elementary quantum of action, the ratio of the energy of a photon to its frequency. It is equal to 6.62620 +/- 0.00005 × 10 to the power -34 Joule-seconds or joules per hertz.
Plane anisotropy – It is a directional property of a material, specifically a difference in a physical property within the plane of a sheet or surface, rather than through its thickness. This means the material behaves differently when measured in different directions aligned with that plane. For example, a sheet metal can have different strengths or deformation behaviours along its rolling direction compared to its transverse direction. This phenomenon is important in manufacturing processes like sheet metal forming, where it can lead to phenomena like ‘earing’ (forming of radial crests) in drawn circular parts.
Plane bending – It describes a structural element bending along a specific plane, frequently characterized by its relation to in-plane (within the plane) and out-of-plane (perpendicular to the plane) stresses and deflections. The phrase ‘plane section remains plane’ is a key assumption in the theory of bending, meaning that a flat cross-section of a beam remains flat after it is been bent, although it can rotate. This assumption is important for calculating stresses and strains within the structure.
Plane bending moment – It is the internal, rotational force within a structural element which causes it to bend mainly in a single plane, such as a beam or a plate. It is a result of external forces applied in a manner which induces a torque, or moment, around an axis, causing a deformation which occurs within a defined, two-dimensional plane.
Plane boundary condition – It refers to a type of boundary condition which is applied to a flat or planar surface within a simulated system, such as a computational fluid dynamics (CFD) simulation or a structural analysis. These conditions specify how the system interacts with the flat boundary, using values like zero velocity for a solid wall, a fixed temperature, or a specific force or stress to define the behaviour at that interface.
Plane deformation – It refers to a 2-dimensional state of strain in which all shape changes of a material occur within a single plane. In a state of plane strain, the third-dimension strain is assumed to be zero, meaning the material deforms only in the x-direction and y-direction while remaining un-deformed in the z-direction. This is a simplification frequently used in engineering to analyze the behaviour of long objects with a large thickness compared to their other dimensions, or for objects like forging where the die walls constrain deformation to a single plane.
Plane grating -It is an optical component which is used to disperse light into its component wave-lengths by diffraction off a series of finely spaced, equidistant ridges. A plane grating has a flat substrate.
Plane of projection – It is an imaginary flat plane upon which the image is projected.
Plane of reference – It is a conceptual or physical flat surface used as a fixed point for measurements, calculations, or descriptions within a specific field or context. In engineering and design, reference planes are used to construct models and define spatial relationships, while in electronics, they can be reference-points for voltage and current.
Plane Poiseuille flow – It is the flow of a Newtonian fluid between two parallel plates, characterized by a parabolic velocity profile and governed by the Navier-Stokes equations under a constant axial pressure gradient.
Planers – They are machine tools which develop the cutting action from the straight-line reciprocating motion between the tool and the work-piece. On a planer, the work is reciprocated longitudinally while the tools are fed sideways into the work. The feed in planning is intermittent and represents width of cut. Planer tables are reciprocated by either mechanical or hydraulic drives. Majority of the planers, however, are mechanically driven by such means as variable-voltage, constant-torque drives.
Plane shear stress – It is the stress state where forces act parallel to a surface, causing layers within a material to slide past each other, or distorting the material along a plane parallel to the applied force. It is quantified by the force applied parallel to the surface divided by the area of that surface. It is the stress state which occurs within a material when it is subjected to loading conditions that mainly induce shear, such as torsion in unidirectional composites. This stress condition can lead to brittle failure mechanisms influenced by maximum tensile stress on inclined planes relative to the fibre direction.
Plane shear test – It is a method for evaluating the shear strength of materials, especially composite laminates, by applying forces parallel to a sample’s surface, causing internal layers to slide against each other. During the test, a material is subjected to in-plane shear stress, and the maximum stress it can withstand before failing is measured. This test is crucial in material characterization and quality assurance for industries like automotive, and construction.
Plane strain – It is the condition in which one of the principal strains is zero. It is the stress condition in linear elastic fracture mechanics in which there is zero strain in direction normal to both the axis of applied tensile stress and the direction of crack growth (i.e., parallel to the crack front)’ It is most nearly achieved in loading thick plates along a direction parallel to the plate surface. Under plane-strain conditions, the plane of fracture instability is normal to the axis of the principal tensile stress.
Plane-strain compression (PSC) test – It is a specialized compression test used to evaluate the flow stress and deformation behaviour of materials, particularly under conditions which mimic flat rolling processes. It involves compressing a rectangular sample between two platens, with the sample’s width being considerably higher than its thickness, hence restricting lateral spread and inducing a state of plane strain (where strain in one direction is negligible).
Plane-strain deformation – It is the deformation because of a two-dimensional strain state. All components of the strain tensor lie in a common plane. Stress-strain constitutive equations then predict a three-dimensional state of stress. The term is used in linear elastic fracture mechanics to indicate a lower value of fracture toughness than plane-stress fracture toughness and a fracture which is macroscale brittle.
Plane-strain fracture toughness (KIc) – It is the crack extension resistance under conditions of crack-tip plane strain. Fracture toughness measured for opening mode loading conditions in which plane-strain conditions exist. Determination of plane-strain fracture toughness is defined as per standards. It is a minimum value of toughness and often identified as KIc.
Plane-strain loading – It is a condition of plastic flow in which there is no normal strain in some direction. In analytical mechanics, it is a statement that there is no displacement in some direction, for example, in the ‘z’ direction, and that displacements in other directions do not depend on ‘z’.
Plane stress – It is the condition in which one of the principal stresses is zero. It is the stress condition in linear elastic fracture mechanics in which the stress in the thickness direction is zero. It is most nearly achieved in loading very thin sheet along a direction parallel to the surface of the sheet. Under plane-stress conditions, the plane of fracture instability is inclined 45-degree to the axis of the principal tensile stress.
Plane-stress fracture toughness (Kc) – In linear elastic fracture mechanics, it is the value of the crack-extension resistance at the instability condition determined from the tangency between the R-curve and the critical crack-extension force curve of the sample.
Plane-stress loading – It is a loading condition in which all force vectors lie in a common plane. The two-dimensional stress state leads to three-dimensional strain.
Planetary gear – It is a gear system which is also called an epicyclic gear. It consists of a central sun gear, surrounding planet gears, and an outer ring gear. The planet gears orbit the sun gear and mesh with the ring gear, with a movable carrier holding the planets. This arrangement provides a compact, high-torque solution with multiple gear ratios by controlling which component rotates, making it suitable for automotive transmissions, and industrial machinery.
Planetary mill roll configuration – In this type of roll configuration, there are a pair of heavy back-up rolls surrounded by a large number of planetary rolls. Each planetary roll gives an almost constant reduction to the feed material as it sweeps out of a circular path between the backup roll and the feed material. As each pair of planetary rolls ceases to have contact with the work piece, another pair of rolls makes contact and repeat the reduction. This configuration is used for giving high reduction in a single pass.
Planetary mixer – It is a machine which allows materials to flow up, down, and around, thereby achieving a mixing effect in a short period of time. (1) The planetary mixer has multiple layers of foldable blades inside the tank, which rotate on their own during revolution, allowing the material to flow up, down, and around the tank, achieving the effect of mixing. The inner wall of the tank is processed by a large vertical lathe and automatically polished by a large polishing machine, ensuring that the movable scraper on the planetary frame can completely scrape off the material on the inner wall of the tank when rotating. The planetary mixer is particularly suitable for dissolving, mixing, mixing, and reaction processes from powder to high viscosity and density materials. Different stirring paddles can be selected as per different production processes and material characteristics, such as multi blade type. In addition, the planetary mixer is also equipped with low-speed mixing components and high-speed dispersion components. The low-speed mixing components use planetary gear transmission to achieve the ideal mixing effect of materials in a short time.
Plane truss – It is a structure composed of slender members which are pin-connected at nodes and undergo axial deformation only, with external loads applied exclusively at these nodes.
Planimetric method – It is a method of measuring grain size in which the grains within a definite area are counted.
Planing – It is a machining process for removing metal from surfaces in horizontal, vertical, or angular planes. It consists of producing flat surfaces by linear reciprocal motion of work and the table to which it is attached, relative to a stationary single-point cutting tool. Although planing is widely used for producing flat, straight surfaces on large work-pieces, the process can also be used to produce contours and a variety of irregular configurations, such as deep slots in large rotors, helical grooves in large rolls, and internal guide surfaces in large valves. It is frequently possible to produce one or two parts on a planer in less time than is needed merely to set up for machining by an alternative method. Hence, planing is frequently used for machining parts to meet production emergencies.
Planishing – It means producing a smooth finish on metal by a rapid succession of blows delivered by highly polished dies or by a hammer designed for the purpose, or by rolling in a planishing mill.
Planishing hammer – It is a tool with a smooth, slightly convex face used for shaping and smoothing metal, particularly in sheet metal work. It is characterized by its ability to refine the surface of metal after initial shaping, often after welding, by flattening and smoothing out any distortions or imperfections. Planishing hammers can be hand-held or power-driven machines.
Planned maintenance – It is that maintenance which is organized and carried out with fore-thought, control, and the use of records to a pre-determined plan.
Planning – It means looking ahead and preparing the organization for the future course of actions which need to be followed. It is a preparatory step and consists of chalking out an activity plan for doing the things in an orderly manner for the achievement of the desired targets and objectives. It is a mental predisposition to think before acting and to act in the light of facts rather than guesses. It is a detailed programme regarding future course of action. It is a systematic activity which determines why an action is needed, what is to done, who has to carry out the action, how it is to be done and when to be done. It bridges the gap between where we are, and where we want to go. It makes possible things to occur which would not otherwise occur. Planning takes into consideration of available and prospective human and physical resources so as to get effective co-ordination, contribution as well as perfect adjustment. It includes formulation of one or more detailed plans to achieve optimum balance of needs or demands with the available resources. Through planning, it is possible to make policies, programmes, procedures, budgeting and other related elements. There are several steps involved in the process of planning. These steps include (i) choosing of goals, (ii) identification of actions, (iii) allocation of responsibilities, (iv) reviewing the performance, and (v) making adjustment in the plan.
Plan of action – It consists of a detailed plan outlining action needed to reach one or more goals. Alternatively, it can be defined as a ‘sequence of steps which are to be taken, or activities which are to be performed well, for a strategy to succeed’.
Plans – Plans are a set of drawings or two-dimensional diagrams which are used to describe a place or object, or to communicate building or fabrication instructions.
Plant – It consists of a building or group of buildings in which different processes or functions are carried out. It is an industrial facility, frequently a complex consisting of several buildings filled with machinery, where workers manufacture items or operate machines which process input raw material into a product.
Plant and equipment – It consists of tangible long-term assets vital to the operations. It means permanent plant, equipment, machinery, apparatus, articles and things of all kinds to be provided and incorporated in the facilities.
Plant commissioning – It refers to the activities from the point in the project when construction is complete (or equipment is installed) until the equipment is placed into service and handed over to the operational team for continued operation and maintenance.
Plant layout – It refers to the arrangement of physical facilities such as machines, equipment, tools, utilities, furnaces, and control rooms etc. in such a manner so as to have quickest flow of material at the lowest cost and with the least quantity of handling in the production of the product from the receipt of the input materials to the dispatch of the finished products. The word ‘plant’ in the plant layout can refer to a production unit of a plant or a complete plant consisting of several production units. Plant layout refers to arrangement of equipments and facilities or plant design. It is a blue print of internal structure and arrangement in a plant. It is a plan for proper and effective utilization of equipments and facilities for the production of the products. It provides smooth flow of materials, and facilitates smooth running of the technological processes in the plant.
Plant operation – It i s the specialized task of managing and optimizing the functioning of plant facilities, which differs considerably from the design of such plants. It also refers to the daily management, maintenance, and optimization of industrial facilities and equipment to ensure efficient, safe, and productive production of goods or services. It involves a wide range of tasks, from monitoring and operating machinery in a control room to performing maintenance and troubleshooting mechanical issues, ultimately ensuring that a plant meets its production targets while adhering to safety and environmental standards.
Plant utilities – These are provided services which are necessary for the efficient operation of the production units. The requirement of utilities is specific to the process and varies depending on the process. Some important plant utilities are water, gases, steam, condensates, fuel oil, air, drains, and flares. Plant utility piping is designed along with product piping. Colours are used to identify different utilities.
Plan view – It is an orthographic projection of a 3-dimensional object from the position of a horizontal plane through the object. In other words, a plan is a section viewed from the top. In such views, the portion of the object above the plane is omitted to reveal what lies beyond. Basically, a plan view is just another name for the top view of a 3D object.
Plasma – It is one of four fundamental states of matter (the other three being solid, liquid, and gas) characterized by the presence of a considerable portion of charged particles in any combination of ions or electrons. It is the most abundant form of ordinary matter in the universe. Plasma can be artificially generated, for example, by heating a neutral gas or subjecting it to a strong electromagnetic field. The presence of charged particles makes plasma electrically conductive, with the dynamics of individual particles and macroscopic plasma motion governed by collective electromagnetic fields and very sensitive to externally applied fields. The response of plasma to electromagnetic fields is used in several modern devices and technologies. Depending on temperature and density, a certain number of neutral particles can also be present, in which case plasma is called partially ionized. Neon signs and lightning are examples of partially ionized plasmas. Unlike the phase transitions between the other three states of matter, the transition to plasma is not well defined and is a matter of interpretation and context. Whether a given degree of ionization suffices to call a substance ‘plasma’ depends on the specific phenomenon being considered.
Plasma arc cutting – It is an arc cutting process which severs metals by melting a localized area with heat from a constricted arc and removing the molten metal with a high-velocity jet of hot, ionized gas issuing from the plasma torch.
Plasma arc cutting torch – It is a tool which utilizes a stream of ionized gas (plasma) to cut electrically conductive materials. It works by creating a concentrated, high-temperature plasma jet which melts and removes material from the work-piece, allowing for precise and efficient cuts.
Plasma arc welding (PAW) – It is an arc welding process which produces coalescence of metals by heating them with a constricted arc between an electrode and the work-piece (transferred arc) or the electrode and the constricting nozzle (non-transferred arc). Shielding is got from hot, ionized gas issuing from an orifice surrounding the electrode and can be supplemented by an auxiliary source of shielding gas, which can be an inert gas or a mixture of gases. Pressure may or may not be used, and filler metal may or may not be supplied.
Plasma-assisted chemical vapour deposition – It is also known as plasma-enhanced chemical vapour deposition. It is a chemical vapour deposition process which uses low-pressure glow-discharge plasmas to promote the chemical deposition reactions. It is also called plasma-enhanced chemical vapour deposition. It is an important technique used for depositing films of a wide variety of crystalline and non-crystalline materials. Examples of films which are normally deposited using this process are non-crystalline materials such as oxides, nitrides, and oxy-nitrides of silicon, and crystalline materials such as poly-crystalline silicon, epitaxial silicon, and refractory metals and their silicides. All of these materials are extensively used in micro-electronic device fabrication, and plasma-assisted chemical vapour deposition is a critical process step in the fabrication of modern silicon devices. Plasma-assisted chemical vapour deposition is also used in depositing optical coatings and other crystalline compounds such as titanium nitride, which is used in highly wear-resistant coatings on cutting tools. Thermally driven atmospheric-pressure and low-pressure chemical vapour deposition (APCVD and LPCVD respectively) are well understood and established methods for depositing films in integrated circuit (IC) fabrication technology. in a thermally driven chemical vapour deposition process can be quite high (e.g., 700 deg C to 900 deg C, for low pressure chemical vapour deposition silicon nitride deposition) and hence are detrimental to modern silicon devices. Plasma enhancement of the chemical vapour deposition process makes it possible to lower the deposition temperature considerably (e.g., to 250 deg C to 300 deg C for plasma assisted chemical vapour deposition of silicon nitride) while maintaining a reasonable rate of deposition and film quality. Hence, some of the advantages of plasma assisted chemical vapour deposition are (i) films can be deposited on substrates which are be unstable at higher temperatures (e.g., intermetallic dielectric layers deposited on aluminum or the encapsulation of integrated circuits), (ii) lower-temperature film deposition in microelectronic circuits allows precise control of dopant migration. The dimensions of modern microelectronic devices are getting smaller, increasing the importance of this control.
Plasma-assisted physical vapour deposition – It is an advanced thin-film coating technique which combines the principles of physical vapour deposition with plasma activation. This method improves the deposition process by using plasma to ionize and excite the vapourized material, improving adhesion, uniformity, and film quality. Plasma-assisted physical vapour deposition is widely used in industries needing high-performance coatings, such as aerospace, automotive, and electronics, because of its ability to produce durable, corrosion-resistant, and temperature-tolerant films at relatively low temperatures. The process uses a plasma discharge as the source of ions for a sputter process, or the sputter process is driven by ions from an ion source. In both cases the ions are accelerated to a solid target, which is the source of the material to be deposited, the film-forming material.
Plasma carburization – In plasma carburization method, plasma impinges positive carbon ions on the surface of a steel part (the cathode). The main difference between conventional and plasma carburization is the reduced carburizing times achieved in plasma methods. The quickly attained surface saturation also results in faster diffusion kinetics. Furthermore, plasma carburizing produces very uniform case depths, even in parts with irregular surfaces. Plasma carburization is increasingly being used in major industrial establishments to improve the surface characteristics (such as wear and corrosion resistance, hardness and load bearing capacity, in addition to quality-based variables) of various steels, especially stainless steels. The process is used as it is environmentally friendly (in comparison to gaseous or solid carburizing). It also provides an even treatment of components with complex geometry (the plasma can penetrate into holes and tight gaps), making it very flexible in terms of component treatment. Plasma carburizing has found applications because of the absence of oxygen in the furnace atmosphere.
Plasma carburizing – It is a method of surface hardening in which carbon ions are diffused into a work-piece in a vacuum through the use of high-voltage electrical energy. It is synonymous with ion carburizing or glow discharge carburizing.
Plasma emission monitor (PEM) – It uses the optical emission spectra from the target material to produce a feedback signal to control the reactive gas flow and more directly monitor the conditions at the target surface. The optical emission spectra from the plasma near the target is collected using a collimator connected to a quartz fibre. This signal is fed into a mono-chromator which is linked to a photo-multiplier. The photo-multiplier outputs an amplified electrical signal to a control unit where the incoming signal level is compared to a preset ‘optimum’ signal level. A control signal is then sent from the control unit to a piezo-electric gas-control valve which is opened or closed in response to a change in the spectral signal. Typically, the optimum reactive gas level is set as some fraction of the spectral peak height of the metallic species. The spectral peak height of pure metal is to be measured for each run just prior to the introduction of the reactive gas, and a thin metallic layer can be deposited before the reactive process attains stoichiometry. In some applications this thin metallic underlayer can create a problem. However, this difficulty can be overcome. The primary advantage of the plasma emission monitor technique is that neither a mass spectrometer nor differential pumping of the sensor is needed, so it is less expensive. This and several similar systems are now commercially available.
Plasma furnaces – Plasma is a partially ionized (up to 50 %) gas which contains electrons, ions, energized molecules, dissociated molecules, neutral molecules, and atoms. The plasma operates at atmospheric pressure and is sufficiently conducting to permit stable transfer of electric power between two or more electrodes. The principal difference between plasma furnaces and arc furnaces is the use of a plasma torch instead of electrodes. In a plasma torch thermionic electrons are emitted from a cathode and accelerated towards the anode. They collide with gas molecules and ionize them. The positively charged gas ions are accelerated in the opposite direction towards the cathode with which they collide, releasing their energy and hence sustaining the thermionic emission. Depending on the type of torch and its construction materials, water cooling can be applied. Several types of alternating current and direct current torches are available. They include transferred arc, non-transferred arc, and superimposed arc. Furnace construction is similar to that of arc resistance and arc furnaces. Refractories and other components are selected to suite the specific application. Plasma furnaces are recent addition into primary and secondary metallurgy.
Plasma immersion ion implantation (PIII) – It is a surface modification technique where a target material is immersed in a plasma and subjected to high-voltage negative pulses to extract and accelerate ions from the plasma, implanting them into the target’s surface layers. This process modifies the material’s near-surface region, altering its physical, chemical, or electrical properties, and is used to improve wear resistance in metals, modify semiconductor properties, and treat different 3-dimensional geometries.
Plasma ion deposition – It is an ion implantation technique in which ion beams are used to create coatings having special phases, especially ion beam formed carbon coatings in the diamond phase or ion beam formed boron nitride coatings.
Plasma-jet excitation – It is the use of a high-temperature plasma jet to excite an element in a sample, e.g., atomic emission spectroscopy. It is also known as direct current plasma excitation.
Plasma-metal inert gas (MIG) welding – Plasma-metal inert gas welding can be defined as a combination of plasma arc welding (PAW) and gas-metal arc welding (GMAW) within a single torch, where a filler wire is fed through the plasma nozzle orifice. The process can be used for both welding and surfacing. Separate power supplies are used for the plasma arc welding and the gas-metal arc welding elements of the equipment. An arc is struck between the tungsten electrode and the work piece in a similar fashion to that of a PAW system. The filler wire can be fed to the plasma arc, either with or without the gas-metal arc welding arc established. Without power supplied to the filler wire, the system can be operated as a plasma arc welding system with concentric feed of filler wire. Later versions of the system incorporated an annular electrode to replace the offset tungsten electrode in the welding torch.
Plasma metallizing – It is a non-standard term for plasma spraying.
Plasma nitriding – It is a method of surface hardening in which nitrogen ions are diffused into a work-piece in a vacuum through the use of high-voltage electrical energy. It is synonymous with ion nitriding or glow discharge nitriding.
Plasma (ion) nitro-carburizing – It is a surface-hardening process using glow discharge technology to introduce nitrogen and carbon into the surface of a part. As in gaseous nitriding, parts are typically heated to a temperature below Ac1 temperature on the nitrogen–carbon–steel phase diagram.
Plasma polymerization – It is a method which uses energy from a plasma to activate monomer gases, which then react to form new, highly crosslinked polymer films on a variety of substrates. This process is a form of chemical vapour deposition (CVD) which creates thin, uniform, and strongly adhering coatings without the need for high temperatures, high pressures, or solvents. The resulting plasma polymers can have their properties, such as surface energy and chemical nature, controlled by adjusting the plasma parameters and monomers used.
Plasma process – It is a set of industrial techniques which use a high-energy electrical discharge to create and utilize a plasma, the fourth state of matter, to modify, treat, or process surfaces of solids, liquids, or gases. This process generates reactive species within the plasma that chemically and physically interact with the target material, enabling applications such as etching, cleaning, coating, and the synthesis of new materials.
Plasma processing – It is a plasma-based material processing technology which aims at modifying the chemical and physical properties of a surface.
Plasma refining – It is a process used to reduce sulphur and oxygen to very low levels.
Plasma rotating electrode process (PREP) – It is a variant on the rotating electrode process (REP). In it, instead of a tungsten electrode, a plasma arc is used to melt the superalloy electrode surface.
Plasma source ion‐implantation (PSII) – It is an ion‐implantation technique which has been optimized for surface modification of materials such as metals, plastics, and ceramics. It departs radically from conventional implantation technology by circumventing the line‐of‐sight restriction inherent in conventional ion implantation. In this technique, targets to be implanted are placed directly in a plasma source and then pulse biased to a high negative potential. A plasma sheath forms around the target and ions bombard the entire target simultaneously. The technique (i) efficiently implants ions to concentrations and depths needed for surface modification, (ii) produces material with improved microhardness and wear properties, and (iii) dramatically improves the life of manufacturing tools in actual industrial applications.
Plasma spray coating – It is a thermal spraying process in which the coating material is melted with the heat of a plasma torch, and the molten melt droplets are propelled against a substrate by the hot, ionized gas of the torch.
Plasma spraying – It is a thermal spraying process in which a non-transferred arc of a plasma torch is utilized to create a gas plasma which acts as the source of heat for melting and propelling the surfacing material to the substrate.
Plasma surface engineering of plastics – Cold gas plasma technology is a preferred industrial process for several applications needing surface chemical modification. Plasma surface treatment, which is conducted in a vacuum environment, affords a wide latitude of possibilities in chemically changing the surface of a plastic to suit a particular application. Three mechanisms which contribute to improvement in the adhesion of two components and the adhesion of coatings are (i) removal of surface contaminants and weakly bound polymer layers. (ii) improvement of wettability through incorporation of polar groups which facilitate spontaneous spreading of adhesive or matrix resin, and (iii) formation of functional groups on the surface which permit covalent bonding. When specialized surface characteristics are needed, coatings with unique chemical and physical characteristics can be deposited by plasma polymerization. Examples include anti-scratch or anti-fog coatings, lubricious coatings, bio-compatible coatings, and chemical and vapour barrier coatings. Since plasma treatment is a process of surface modification, the bulk properties of the material are retained. The nature of the process also allows precise control of the process parameters and ensures repeatability of the process in industrial applications. Also, these surface modifications can be achieved with minimal impact on the environment.
Plasma techniques – These techniques refer to the application of plasma, a state of matter composed of ionized gas, to various processes like surface treatment, melting, cutting, and material recovery. These techniques leverage plasma’s high temperature and energy to modify material properties, facilitate melting and vaporization, and enable efficient separation of metals from waste or ores.
Plasma transferred arc welding – It is a surface welding method, which enables a metallurgical bonding with the base material. It is versatile since it can be used on majority of the alloys. The high-energy plasma transferred arc melts the surface of the base material.
Plasmon – It is a quantum of a collective longitudinal wave in the electron gas of a solid.
Plaster moulding – It is moulding in which a gypsum-bonded aggregate flour in the form of a water slurry is poured over a pattern, permitted to harden, and, after removal of the pattern, thoroughly dried. This technique is used to make smooth non-ferrous castings of accurate size.
Plaster mould casting – Plaster mould casting is a specialized casting process used to produce non-ferrous castings which have high dimensional accuracy, smoother surfaces, and more finely reproduced detail than can be achieved in sand moulds or coated permanent moulds. The four normally recognized plaster mould processes are (i) conventional plaster mould casting, (ii) match plate pattern plaster mould casting, (iii) the Antioch process, and (iv) the foamed plaster process.
Plaster of Paris – It is a fine white powder, which, when mixed with water gets a clay-like consistency and can be shaped around the pattern. The plaster cast can be finished to yield very good surface finish and dimensional accuracy. However, it is relatively soft and not strong enough at temperature above 1,200 deg C, so this method is mainly used to make castings from non-ferrous metals such as zinc, copper, aluminum, and magnesium.
Plastic – It is a material which contains as an essential ingredient an organic polymer of large molecular weight. Plastic is solid in its finished state, and, at some stage in its manufacture or its processing into finished articles, can be shaped by flow. Although materials such as rubber, textiles, adhesives, and paint can also in some cases meet this definition, they are not considered plastics. The terms plastic, resin, and polymer are somewhat synonymous, but the terms resins and polymers very frequently denote the basic material as polymerized, while the term plastic encompasses compounds containing plasticizers, stabilizers, fillers, and other additives.
Plastic deformation – It is the permanent (inelastic) distortion of materials under applied stresses which strain the material beyond its elastic limit. Plastic deformation is observed in most materials, particularly metals and alloys, soils, rocks, concrete, and foams. However, the physical mechanisms which cause plastic deformation can vary widely. At a crystalline scale, plasticity in metals is normally a consequence of dislocations. Such defects are relatively rare in majority of the crystalline materials, but are many in some and part of their crystal structure. In such cases, plastic crystallinity can result. In brittle materials such as rock, and concrete, plasticity is caused predominantly by slip at microcracks. In cellular materials such as liquid foams, plasticity is mainly a result of bubble rearrangements. For several ductile metals, tensile loading applied to a sample causes it to behave in an elastic manner. Each increment of load is accompanied by a proportional increment in extension. When the load is removed, the piece returns to its original size. However, once the load exceeds a threshold, the yield strength, the extension increases more rapidly than in the elastic region, and now when the load is removed, some degree of extension remains.
Plastic fireclay refractory – It is a fireclay refractory material tempered with water and suitable for ramming into place to form a monolithic furnace lining which attains satisfactory physical properties when subjected to the heat of furnace operation.
Plastic flow – It is the phenomenon which takes place when metals are stretched or compressed permanently without rupture. It refers to the irreversible deformation of a material under stress, where the material does not return to its original shape after the stress is removed. It is a type of plastic deformation which occurs when a material is stressed beyond its elastic limit, causing a permanent change in shape. This flow is characterized by the material behaving like a viscous fluid under stress, and it can occur under sustained forces (creep) or high forces.
Plastic hinge – It is the deformation of a section of a beam where plastic bending occurs. In earthquake engineering plastic hinge is also a type of energy damping device allowing plastic rotation (deformation) of an otherwise rigid column connection.
Plastic instability – It is the stage of deformation in a tensile test where the plastic flow becomes nonuniform and necking begins.
Plasticity – It is the property of a material which allows it to be repeatedly deformed without rupture when acted upon by a force sufficient to cause deformation and which allows it to retain its shape after the applied force has been removed. Plasticity is the ability of a solid material to undergo permanent deformation, a non-reversible change of shape in response to applied forces. For example, a solid piece of metal being bent or pounded into a new shape displays plasticity as permanent changes occur within the material itself. In engineering, the transition from elastic behaviour to plastic behaviour is known as yielding.
Plasticity, coal – It refers to the melting and bonding behaviour of the coal. It is the ability for coal to soften and become plastic when heated, and then to re-solidify into a coke. It is an indication of the initial softening, chemical reaction, gas liberation, and re-solidification process within the coke oven. It is an important requirement in the coal blend and is required for the strength of the end product coke. The fluidity of the plastic stage is a major factor in determining what proportions of a coal is used in a blend.
Plasticity-induced crack closure (PICC) – It is a phenomenon where plastic deformation in the material around a fatigue crack tip causes the crack surfaces to remain closed or partially closed even when the applied load decreases during a loading cycle. This closure, caused by a ‘wedge’ of plastically deformed material behind the crack tip, reduces the effective stress acting on the crack and hence slows the crack growth rate.
Plasticizer – It is a substance that is added to a material to make it softer and more flexible, to increase its plasticity, to decrease its viscosity, and / or to decrease friction during its handling in manufacture. Plasticizers are also frequently added to concrete formulations to make them more workable and fluid for pouring, hence allowing the water contents to be reduced.
Plastic lubricants – These lubricants are semi-liquids such as grease.
Plastic memory – It is the tendency of a thermoplastic material which has been stretched while hot to return to its unstretched shape upon being reheated.
Plastic or bond fireclay – It is a fireclay of sufficient natural plasticity to bond non-plastic materials.
Plastic pattern – It is a pattern made from any of the several thermosetting-type synthetic resins such as phenol formaldehyde, epoxy, etc. Small patterns can be cast solid, but large ones are normally produced by laminating with glass cloth.
Plastic pipes – Plastic pipe is widely used for its light weight, chemical resistance, non-corrosive properties, and ease of making connections. Different type of plastic materials can be used for plastic pipes.
Plastic pollution – It is the excessive accumulation of synthetic plastic objects and particles in the environment, stemming from human activities like increased production and improper disposal of plastic products. Since plastics are durable and resist natural decomposition, they persist for decades, harming wildlife, ecosystems, and human health through physical entanglement, ingestion, and chemical release. This form of environmental contamination is found world-wide, from oceans and land to air and soil, and is a substantial global challenge.
Plastic refractory material – It is a refractory material, tempered with water, which can be extruded and which has suitable workability to be pounded into place to form a monolithic structure’
Plastic refractory – It is the unshaped refractory, supplied ready for use, with a high workability, made up of aggregate, bond and liquid, and which hardens after placing by the action of heat. As per the type of product, the main bond can be ceramic, chemical, or organic. Plastic refractory materials are normally supplied in soft, pre-formed blocks or slices and placed by ramming (mechanical or manual).
Plastic replica – In fractography and metallography, a reproduction in plastic of the surface to be studied. It is prepared by evaporation of the solvent from a solution of plastic, polymerization of a monomer, or solidification of a plastic on the surface.
Plastic strain – It consists of dimensional change which does not disappear when the initiating stress is removed. It is normally accompanied by some elastic deformation.
Plastic strain rate – It is the rate at which a material undergoes permanent (plastic) deformation over time, meaning how quickly it changes shape in a non-recoverable way after its elastic limit has been exceeded. It quantifies the speed of plastic deformation and is an important parameter, influencing material behaviour under stress, particularly in models of elasto-viscoplasticity.
Plastic-strain ratio (r-value) – In formability testing of metals, it is the ratio of the true width strain to the true thickness strain in a sheet tensile test, r = Ew.Et. A formability parameter which relates to drawing, it is also known as the anisotropy factor. A high r-value indicates a material with good drawing properties.
Plastic yield point – It is the stress level on a material’s stress-strain curve where it transitions from elastic deformation (returning to its original shape) to plastic deformation (permanently changing its shape). Below this yield point, the material behaves elastically, while above it, the material undergoes irreversible changes and does not fully recover its original form when the stress is removed.
Plastic-zone adjustment, rY – It is an addition to the physical crack size to account for plastic crack-tip deformation enclosed by a linear elastic stress field.
Plastisol – It is a suspension of a finely divided resin in a plasticizer which can be converted to a continuous film by the application of heat. Distinct from baking enamels etc. in that substantially all the original mixture becomes a part of the film; there is no significant evaporation of solvent. The films are normally much thicker than obtainable from coatings that depend on the evaporation of a volatile solvent.
Plastisol coating – It is the polyvinyl chloride (PVC) covering on materials. On roller tubes on a conveying system, it is done to prevent product damage or marking. It is normally green, blue, or red in colour.
Plasto-hydrodynamic lubrication – It is a condition of lubrication in which the friction and film thickness between two bodies in relative motion are determined by plastic deformation of the bodies in combination with the viscous properties of the lubricant at the prevailing pressure, temperature, and rate of shear.
Plate – Plate is a structural element which is characterized by a three-dimensional solid whose thickness is very small when compared with other dimensions. It is a flat-rolled metal product of some minimum thickness and width arbitrarily dependent on the type of metal. Plate thicknesses commonly range from 6 millimeters to 300 millimeters and widths from 200 millimeters to 2,000 millimeters.
Plate, alclad – it is the composite plate composed of an aluminum alloy core having on both surfaces (if on one side only, alclad one-side plate) a metallurgically bonded aluminum or aluminum alloy coating that is anodic to the core, hence electrolytically protecting the core against corrosion.
Plate bending – It is the deformation of a flat plate under lateral (perpendicular) load, causing it to deflect and develop internal stresses and moments. It is also a manufacturing process which shapes a flat metal plate into a curved or angled form using machines like a press brake.
Plates, bottom – These are plates, normally of steel, on which moulds are set for pouring.
Plate circle – It is a circle cut from plate.
Plate cooler – It is also known as a plate heat exchanger. It is a device which transfers heat between two fluids using a series of thin, corrugated metal plates. These plates are stacked together, creating channels for the hot and cold fluids to flow through, separated by the plates. This design maximizes the surface area for heat transfer, making it highly efficient.
Plates, core drying – These are flat plates of metal on which cores are placed for baking.
Plate girder – It is a large, I-shaped beam made from separate steel plates which are welded or bolted together to form a strong structure for carrying heavy loads over long spans. It consists of a central vertical web plate to resist shear forces and two horizontal flanges (top and bottom) which resist bending, much like a standard I-beam. Plate girders are used in bridges and large buildings when standard rolled I-beams are insufficient to support the required loads.
Plate heat exchanger is a type of heat exchanger that uses metal plates to transfer heat between two fluids. This has a major advantage over a conventional heat exchanger in that the fluids are exposed to a much larger surface area because the fluids are spread out over the plates. This facilitates the transfer of heat, and greatly increases the speed of the temperature change. Plate heat exchangers are now common and very small brazed versions are used in the hot-water sections of millions of combination boilers. The high heat transfer efficiency for such a small physical size has increased the domestic hot water (DHW) flowrate of combination boilers. The small plate heat exchanger has made a great impact in domestic heating and hot-water. Larger commercial versions use gaskets between the plates, whereas smaller versions tend to be brazed. The concept behind a heat exchanger is the use of pipes or other containment vessels to heat or cool one fluid by transferring heat between it and another fluid. In most cases, the exchanger consists of a coiled pipe containing one fluid that passes through a chamber containing another fluid. The walls of the pipe are usually made of metal, or another substance with a high thermal conductivity, to facilitate the interchange, whereas the outer casing of the larger chamber is made of a plastic or coated with thermal insulation, to discourage heat from escaping from the exchanger.
Platelets – These are also known as plates. These are flat particles of metal powder having considerable thickness. The thickness, however, is smaller when compared to the length and width of the particles.
Platelet shaped inclusions – These are manganese sulphides and oxy-sulphides inclusions in form of thin films (platelets) located along the steel grain boundaries. These inclusions are formed because of deoxidation of steels by aluminum. Such inclusions are formed as a result of eutectic transformation during solidification. Platelet shaped inclusions are not desirable. They considerably weaken the grain boundaries and cause adverse effects on the mechanical properties particularly in hot condition (hot shortness).
Plate martensite – It is the martensite formed partly in steel containing more than around 0.5 % carbon and solely in steel containing more than around 1 % carbon which appears as lenticular-shape plates (crystals).
Plate mills – These are flat mills for the rolling of heavy plates. These mills normally include on-line heat treatment of the rolled plates.
Platen – It is the mounting plates of a press, to which the entire mould assembly is bolted. It is the sliding member, slide, or ram of a metal forming press. It is a part of a resistance welding, mechanical testing, or other machine with a flat surface to which dies, fixtures, back-ups, or electrode holders are attached and which transmits pressure or force.
Plate orifice – It is a thin plate with a precisely sized circular hole, installed in a pipeline to measure fluid flow, reduce pressure, or restrict the flow rate. By forcing fluid through the narrow opening, the velocity of the fluid increases, and the pressure drops, a phenomenon explained by Bernoulli’s principle. Measuring the resulting pressure difference allows for the calculation of the fluid’s volumetric or mass flow rate.
Plate rolling – It is a metalworking process which bends flat metal sheets / plates into cylindrical or conical shapes using a plate rolling machine, which passes the sheet /plate through sets of rollers to apply pressure and deformation. This fabrication technique is used to create large-diameter pipes, tanks, pressure vessels, and other structural components across industries.
Plate specification – It is a document or set of criteria which details the needed characteristics of a metal plate, including its material grade, chemical composition, mechanical properties (like strength and hardness), dimensions (thickness, width, and length), surface finish, manufacturing process, and any applicable standards or certifications. These specifications ensure the plate is suitable for its intended application, such as in construction, shipbuilding, or pressure vessels, by guaranteeing it meets specific performance and safety requirements.
Plate tectonics – It is a geological theory which postulates that the earth’s crust is made up of a number of rigid plates which collide, rub up against and spread out from one another.
Platform – It is a raised structural surface designed to hold or provide access to the equipment or machinery.
Platform crane – It is a broad term referring to a crane mounted on a stable structure or platform, such as a ship, an offshore oil rig, or a railway platform, to facilitate lifting and loading operations in that specific environment. The term can also refer to a platform crane tower, a type of tower crane mounted on a mobile, rail-based platform for movement at a construction site.
Plating – It is forming an adherent layer of metal on an object. It is frequently used as a shop term for electroplating.
Plating cracks – Plating cracks are surface discontinuities which can develop due to the penetration of hydrogen or hot plating material into the base metal. Also, some plating materials (such as chromium, copper, or nickel) produce residual tensile stress which can reduce the fatigue strength of a component.
Plating process – It involves applying a thin metal layer to a substrate to improve its properties or appearance. The main methods are electroplating, which uses electricity and a chemical solution to deposit the metal, and electroless plating, which relies on simultaneous chemical reactions. This process improves characteristics like corrosion resistance, wear, solderability, and conductivity, and provides decorative finishes.
Plating rack – It is a fixture used to hold work and conduct current to it during electro-plating.
Plating thickness – It is the measurement of the depth of a metal layer applied to a substrate material through methods like electroplating or electroless plating. It is a crucial quality control parameter which ensures a coating provides necessary properties such as corrosion resistance, hardness, electrical conductivity, or decorative appeal. The thickness, frequently measured in micro-meters. It is controlled by factors like plating time and solution temperature, with variations leading to issues like poor coverage or premature failure.
Platinum (Pt) – It is a chemical element having atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. It is a member of the platinum group of elements and group 10 of the periodic table of elements. It has six naturally occurring isotopes. It is one of the rarer elements in earth’s crust. Platinum is one of the least reactive metals. It has remarkable resistance to corrosion, even at high temperatures, and is hence considered a noble metal.
Platinum acetyl-acetonate – It is a yellow solid coordination compound of platinum(II) with two acetyl-acetonate ligands, with the chemical formula Pt(C5H7O2)2, or Pt(acac)2. It is a stable, organic platinum precursor used as a source of platinum in various applications, including the preparation of platinum nano-particles, catalysts for organic synthesis, and thin films through methods like chemical vapour deposition (CVD) and atomic layer deposition (ALD).
Platinum catalyst – It is a platinum-containing substance which increases the rate of a chemical reaction without being permanently consumed in the process. Platinum’s unique electronic properties allow it to bind reaction intermediates, lower activation energies, and facilitate chemical transformations, making it highly effective in various industrial and automotive applications, such as catalytic converters for reducing exhaust emissions and in organic synthesis.
Platinum crystal – It is a solid, periodic, three-dimensional arrangement of platinum (Pt) atoms which forms a crystal structure, such as the face-centered cubic (fcc) structure it adopts at room temperature. This precise atomic arrangement can give rise to a defined crystal class and symmetry, forming the basis of the material’s properties.
Platinum electrode – It is an electrically conductive surface made from platinum, a noble and chemically inert metal, which serves as a conductor and catalyst in electro-chemical processes. Its key property is its high resistance to corrosion and its ability to facilitate electron transfer without participating in the main chemical reactions of a cell, making it ideal for applications like fuel cells, electrolysis, and as a reference electrode.
Platinum-group metals (PGMs) – These are six noble, precious metallic elements clustered together in the periodic table. These elements are all transition metals in the d-block. The six platinum-group metals are ruthenium, rhodium, palladium, osmium, iridium, and platinum. They have similar physical and chemical properties, and tend to occur together in the same mineral deposits.
Platinum nanoparticles – These are incredibly small particles of platinum, typically ranging from 2 nanometers to 100 nanometers in size. These inorganic nanoparticles are frequently dispersed in a liquid, forming a colloidal suspension, and are used for different applications, including catalysis, and creating novel materials. Their effectiveness in these roles is influenced by their size, shape, and stability within different environments
Platinum resistance thermometer – It is a temperature sensor which functions on the principle that the electrical resistance of a pure platinum element changes predictably with temperature. By measuring this change in resistance, normally for a platinum coil or thin film with a standard resistance of 100 ohms at 0 deg C, the device provides accurate and stable temperature readings, frequently with high repeatability and a linear resistance-temperature relationship.
Platinum resistance thermometer (PRT) detector – It is also known as a resistance temperature detector (RTD). It is a temperature-measuring device which uses the principle that the electrical resistance of pure platinum changes predictably with temperature. It consists of a platinum wire or thin film whose resistance is measured when a current passes through it, allowing for highly accurate, stable, and reproducible temperature readings over a wide range.
Platinum rhodium alloy – It is a mixture of the metals platinum and rhodium, forming a solid solution which is used in high-temperature applications like thermocouples and furnace windings, and in catalytic processes. Rhodium improves platinum’s resistance to oxidation, corrosion, and heat, particularly at temperatures above 1,000 deg C, making the alloy stable and robust for demanding environments such as the glass industry.
Platinum sensor – It is a sensing device, frequently a platinum resistance thermometer (PRT), which uses the predictable, linear change in platinum’s electrical resistance with temperature to accurately measure and control temperature. Since platinum is stable, resistant to corrosion, and shows excellent linearity, it provides precise and reproducible temperature readings across a wide range. These sensors are constructed using platinum wire or thin films on ceramic substrates and are critical in industrial and scientific applications needing high accuracy, such as process control and safety monitoring.
Platinum thermocouple – It is a high-precision temperature sensor made from platinum, frequently alloyed with rhodium, which measures temperature by generating a voltage proportional to the temperature difference between its two junctions. Its exceptional stability, resistance to corrosion, and high melting point make it ideal for high-temperature industrial applications, such as n semiconductor, glass, and steel manufacturing.
Platonic solids – These are a special type of convex, regular polyhedron in three-dimensional space. They are characterized by having identical, regular polygons as faces and the same number of faces meeting at each vertex. There are only five such solids namely the tetrahedron, cube, octahedron, dodecahedron, and icosahedron.
Plenum – It is a space completely filled with matter.
Plenum cable – It is the electrical cable permitted in plenum spaces per building codes. It is a fire-resistant data communications cable which is permitted to be installed in the air handling spaces of a modern building.
Plenum chamber – It is a chamber intended to contain air, gas, or liquid at positive pressure. In case of plasma arc welding and cutting, and plasma spraying, it is the space between the inside wall of the constricting nozzle and the electrode.
Plenum (meeting) – It is a meeting of a deliberative assembly in which all members are present; contrast with quorum.
Plenum space – It is enclosed spaces (in buildings) used for airflow.
Plexiglas – It is a type of acrylic plastic, known chemically as poly-methyl-methacrylate (PMMA), which offers high transparency (93 %), low weight (50 % less than glass of equal thickness), and excellent durability, making it suitable for a variety of applications such as lenses, lighting fixtures, and outdoor signs.
Plied yarn – It is the yarn made by collecting two or more single yarns. Normally, the yarns are twisted together, though sometimes they are collected without twist.
Plinth level – In construction, plinth level refers to the level at which the foundation of a building transitions into the superstructure, typically the ground floor. It is the base upon which the walls and other structural elements of the building are constructed, and it is normally several centimeters above the surrounding ground level.
Plot plan – It is a detailed, scaled, top-down drawing which shows the physical layout of a facility or project, showing the placement of equipment, buildings, roads, and other essential infrastructure within a designated boundary. This important document serves as a roadmap for design, construction, and operations, ensuring efficient use of space and addressing safety, accessibility, and operational considerations.
Plow – It is also spelled as plough. It is a mechanism strategically positioned across the conveyor path at the appropriate angle to discharge or divert objects.
Plowing – It is also written as ploughing. In tribology, it is the formation of grooves by plastic deformation of the softer of two surfaces in relative motion. The contribution of plowing to frictional resistance is to be distinguished from the contribution of shearing, especially in the classical hemisphere-on-flat model system. In plowing, local solid-phase welding is ignored.
Ploughing component of friction – It originates from the deformation force acting during the ploughing of the softest material in contact by the surface asperities of the harder material and is related to the surface topography. Also, deformation hardened wear particles attached in the interface act in a ploughing way. One additional part to the ploughing component is the asperity deformation which is related to the deformation of the asperities on micro level.
Ploughing friction – It is also written as plowing friction. It is a component of the total frictional force which arises when hard asperities (microscopic irregularities) on one surface penetrate and displace the material of a softer contacting surface during relative sliding motion. This deformation of the softer material, which can create grooves or piled-up material, needs a force to overcome, contributing to the resistance to motion. The magnitude of this contribution is influenced by factors such as the hardness difference between the two surfaces, the cross-sectional area of the groove formed, and the material properties of the softer surface.
Ploughing force – It is a resistance force which occurs when a sharp object, such as a tool’s cutting edge or a hard asperity, penetrates and deforms a softer material, displacing it rather than cutting it away. It is a parasitic force, analogous to agricultural plowing, which contributes to overall cutting forces, increased energy consumption, and impacts surface quality and tool wear in machining processes, especially at micro-scales where the tool’s edge radius is substantial.
Plug – It is a rod or mandrel over which a pierced tube is forced. It is a rod or mandrel which fills a tube as it is drawn through a die. It is a punch or mandrel over which a cup is drawn. It is a protruding portion of a die impression for forming a corresponding recess in the forging. It is a false bottom in a die. In geology, plug is a common name for a small offshoot from a large body of molten rock. In case of valve, plug is the rotating closure element of a plug valve. It is also, a threaded fitting used to close off and seal an opening into a pressure-containing chamber, e.g., pipe plug. Plug is also the connector attached to an electrically operated device, frequently through a cable. It is a device attached to the end of a flexible cable with metal pins that fits into a socket or receptacle to connect an electrical device to a power source.
Plug, eccentric – It is a style of rotary control valve with an eccentrically-rotating plug which cams into and out of the seat, which reduces friction and wear. This style of valve is well suited for erosive applications.
Plug gauge – It is a precision measuring tool which used to verify the size and shape of a hole or bore, ensuring it meets specified tolerances. It is essentially a cylindrical piece with two gauging surfaces namely (i) a ‘Go’ end which represents the minimum acceptable size and a ‘No-Go’ end which represents the maximum acceptable size.
Plugged chute switch – It is a safety device which is integrated into a conveyor system to identify and address material blockages in chutes, necessitating routine inspections for proper functionality and system safety.
Plugged pile – It refers to an open-ended pile where the internal soil column moves with the pile, forming a soil plug which impedes further soil entry. This condition, which can be fully or partially plugged, considerably affects the pile’s installation behaviour and load-bearing capacity, increasing end-bearing resistance and reducing the reliance on shaft friction compared to an unplugged or partially unplugged pile.
Plug quenching – It is a specialized heat treatment process where a metal component, typically a ring or sleeve, is rapidly cooled (quenched) while its bore is restrained by a plug. This technique is used to control the final dimensions of the bore after hardening, minimizing distortion, especially in thin-walled components.
Plug rolling process – This rolling process is used for rolling seamless pipes in the diameter range from around 60 millimeters to 406 millimeters with wall thicknesses from around 3 millimeters to 40 millimeters and pipe lengths ranging between 12 meters and 16 meters. In this mill piercing is done in a cross-roll piercing mill to produce a thin wall hollow shell which is elongated to between 3 times and 4.5 times of its original length, corresponding to a deformation level of 65 % to 75 %. The cross-roll piercing mill has two driven work rolls featuring a biconical pass. The axes of the rolls are parallel to the stock and are inclined to the horizontal by between 6-degree and 12-degree. The gap between the work-rolls is adjusted extensively by a top and bottom guide shoe. These guide shoes contribute to the elongation process by acting as stationary rolls, so enabling production of a thin-walled hollow shell. The stock follows a helical line as it passes through the roll gap, so enabling the piercing mandrel, acting as an internal tool, to displace the material more effectively. Owing to the relatively large angle of roll inclination, and higher rolling speeds, stock exit speed is considerably faster. This is necessary owing to the cycle time of the downstream plug strand. In case of large pipe diameters, there is a second piercing mill (also called an elongator) before the plug stand. Recent heavy-duty plug mills have only one cone piercing unit with work rolls featuring a biconical design. They are each angled at around 30-degree to the hollow stock axis and inclined at around 10-degree to 12-degree to the horizontal. The roll gap is closed by means of two side discs which are also driven. The process of forming the hollow shell into the finished pipe is carried out in the downstream plug stand with around two fold elongation (50 % cross sectional reduction), with normally two rolling passes being applied. In the plug stand are mounted the two cylindrical work rolls which are provided with approximately circular grooves, and also the two separately driven stripper rolls. A plug, which is located at the roll pass centre, is held in position by a mandrel supported by a thrust block located downstream of the rolling stand. The resultant annular gap between the rolls and plug correspond to the finished pipe wall thickness.
Plug tap – It is a tap with chamfer extending from three to five threads.
Plug valves – Plug valves are valves with cylindrical or conically-tapered ‘plugs’ which can be rotated inside the valve body to control flow through the valve. The plugs in plug valves have one or more hollow passage ways going sideways through the plug, so that fluid can flow through the plug when the valve is open. Plug valves are simple and often economical. There are two types of plug valves. One has a port through a cylindrical plug which is perpendicular to the pipe and rotates to allow the fluid to proceed through the valve if in an open configuration. In the closed configuration, the cylinder rotates about its axis so that its port is no longer open to the flow of fluid. An advantage of these types of valves is that they are excellent for quick shut-off. The high friction resulting from the design, however, limits their use for accurate modulating / throttling.
Plug weld – It is a weld made in a circular hole in one member of a joint, fusing which member to another member.
Plug welding – It is a technique where a weld is made through a hole in one piece of overlapping metal, fusing it to the piece below. It is essentially a spot weld performed within a hole, and is frequently used when spot welding equipment cannot reach the area. The resulting weld can be stronger than a spot weld.
Plumbage – It is a special quality of powdered graphite which is used to coat moulds and, in a mixture of clay, to make crucibles.
Plumbago – It is older term for natural graphite which is used for drawing, typically as a lump of the mineral without a wood casing. It is used in making pencils.
Plumber – Plumber is a tradesperson who specializes in installing and maintaining systems used for potable (drinking) water, hot-water production, sewage and drainage in plumbing systems. Plumbers are skilled professionals.
Plumbing – It deals with piping in buildings which carry water, gas, and wastes in the industrial buildings. Here, pipes sizes are normally small and are made from materials such as copper, steel, cast iron, and plastic.
Plumbing pipe – It is a cylindrical component within a plumbing system designed to transport fluids, such as potable water or wastewater, and manage stormwater discharge. These pipes are engineered from different materials, including copper, cast iron, and different types of plastics, with their design and material selection based on factors such as pressure, temperature, fluid type, and longevity needs.
Plumb line – It is a cord with a heavy weight (a plumb bob) attached to one end, used to establish a true vertical line by suspending it so it hangs directly towards the earth’s centre of gravity. This vertical reference is necessary for checking that a structure or component, such as a wall, is perfectly straight and perpendicular to the horizontal.
Plume – It is a vertical body of one fluid moving through another. Several effects control the motion of the fluid, including momentum (inertia), diffusion and buoyancy (density differences). Pure jets and pure plumes define flows which are driven entirely by momentum and buoyancy effects, respectively. Flows between these two limits are normally described as forced plumes or buoyant jets.
Plummer block – It normally refers to a heavy or very heavy-duty housing, always in two pieces. The lower piece is bolted to the base plate or foundation, then the bearing and shaft are rested on it, and the cap is bolted down to the lower piece. Plummer block bearings may be designed for more corrosive environments.
Plunge – It is the vertical angle which a linear geological feature makes with the horizontal plane.
Plunge grinding – It is the grinding wherein the only relative motion of the wheel is radially toward the work.
Plunger – It is the ram or piston which forces molten metal into a die in a die casting machine.
Plunger diameter – It is the measured dimension across the circular face of a plunger, a component which moves in relation to another part to transmit force or pressure. This diameter is crucial for calculating and defining the plunger’s performance, especially in systems like plunger pumps (e.g., for hydrodemolition) or hydraulic presses, where it influences the quantity of force generated or the pressure applied. It is a key parameter for designing and analyzing how these components function.
Plunger machines – These are those machines which are having a plunger in continuous contact with molten metal.
Plunger pump – It is a type of positive displacement pump where the high-pressure seal is stationary and a smooth cylindrical plunger slides through the seal. This makes them different from piston pumps and allows them to be used at higher pressures. A reciprocating plunger pushes the fluid through one or two open valves, closed by suction on the way back.
Pluralize – In the records continuum – a spacetime model, pluralize is the fourth dimension which embeds the records into the organization in which they reside and ensures that the records can be added beyond the service period of the people of the organization to the organizational memory.
Plus-mesh – It is the powder sample retained on a screen of stated size, identified by the retaining mesh number.
Plus-sieve – It is the portion of a sample of a granular substance (such as metal powder) which is retained on a standard sieve of specified number. It is contrast with minus sieve.
Plutonic – It refers to rocks of igneous origin which have come from great depth.
Plutonium (Pu) – It is a heavy, radioactive, man-made metallic element with atomic number 94. There are thirteen known isotopes of plutonium, the most important of which in the nuclear industry is isotope Pu-239 which undergoes fission with slow-moving neutrons.
Ply – It is a layer of material which has been combined with other layers in order to provide strength. The number of layers is indicated by prefixing a number, e.g., 4-ply, indicating material composed of 4 layers. In general, fabrics or felts consisting of one or more layers (laminates, and so on). It also consists of the layers which make up a stack. It also consists of yarn resulting from twisting operations (three-ply yarn, and so on). It is a single layer of prepreg. It is also a single pass in filament winding (two plies forming one layer).
Ply-metal – It is the sheet consisting of bonded layers of dissimilar metals.
P-matrix – It can refer to at least two different concepts: a P-matrix is a square matrix where all its principal minors are positive, a property used in certain mathematical applications, while a P-matrix in the context of Markov chains is a state transition probability matrix (a ‘P’ for ‘probability’) where each entry represents the probability of transitioning from one state to another.
P/M – It is the acronym for powder metallurgy.
P/M part – It is a shaped object which has been formed from metal powders and bonded by heating below the melting point of the major constituent. It is a structural or mechanical component, bearing or bushing made by the powder metallurgy process
PMR polyimides – It consists of a novel class of high-temperature-resistant polymers. PMR represents in situ polymerization of monomer reactants.
P-network – It is a type of artificial neural network which uses a Bayesian decision strategy for classifying input vectors, featuring a feed-forward architecture with specific input and output neuron configurations.
Pneumatic actuator – It is a device which converts energy typically in the form of compressed air into mechanical motion. Within the industry, pneumatic actuators are recognized by several different names including pneumatic cylinders, air cylinders, and air actuators. Consisting of a piston, cylinder, and valves or ports, a pneumatic actuator can convert energy into linear or rotary mechanical motions. This is dependent on whether the application is using a pneumatic rotary actuator or a linear actuator.
Pneumatic chisel – It is a handheld power tool which uses compressed air to drive a chisel bit. It is designed for different tasks like cutting, shaping, and removing materials like metal, stone, or concrete. The compressed air powers a piston inside the tool, which rapidly strikes the chisel bit, creating a hammering action.
Pneumatic component – It is a part of a pneumatic system which uses compressed air or gas to perform work, control motion, or regulate the system. These components include power sources (air compressors), air treatment units (filters, regulators), control elements (valves, sensors), and actuators like cylinders and motors which convert air pressure into mechanical movement. They are necessary for automation in several industries because of their safety, cleanliness, and reliability in performing tasks like lifting, clamping, and material handling.
Pneumatic control – It is an automated system which uses compressed air or other gases to transmit signals and generate mechanical motion to operate machinery and processes. These systems are used in different industries to provide reliable, clean, and cost-effective control of mechanical components like valves and actuators. Key components include air compressors, storage tanks, treatment units, and control devices, which work together to convert air pressure into precise mechanical actions.
Pneumatic conveying systems – Pneumatic conveying is the process of conveying granular / powdered materials by floating the materials in a gas, mainly air, and then allowing it to flow to the destination through a closed pipe. The operating principle common to all types of pneumatic conveying is that motion is imparted to the material by a fast-moving stream of air. Hence, any pneumatic conveyor consists of an air supply equipment (blower or compressor), pipelines, product storages, air lock feeders and dust filters. Pneumatic conveying system is used for delivery of non-sticky, dry materials via pipelines to various storage or process points which are economically inaccessible by conventional conveyors.
Pneumatic conveyor – It is a conveyor system employing air pressure for material transport, needing regular assessments of pneumatic system integrity, pressure levels, and overall efficiency.
Pneumatic cylinder – It is a constituent of a conveyor system utilizing compressed air for generating linear motion, calling for periodic inspections to check for leaks, pressure levels, and overall cylinder performance. It is also known as air cylinder. It is a mechanical device which uses the power of compressed gas to produce a force in a reciprocating linear motion.
Pneumatic drive – It is a system which uses compressed air to convert energy into controlled mechanical motion, typically linear or rotational. These systems work by directing pressurized air through components like compressors, control valves, and actuators (e.g., cylinders or motors) to move machinery, or other devices. Pneumatic drives are valued for their safety, speed, simplicity, and low maintenance, making them suitable for several industrial applications.
Pneumatic hammer – It is also known as an air hammer or power hammer, is a tool which uses compressed air to drive a reciprocating piston, which then delivers a forceful impact. This impact can be used for several tasks, such as driving rivets, breaking rocks (jack-hammer), or shaping metal in forging.
Pneumatic hoists – These are also called air hoists. These are powered by pneumatically driven motors. When equipped with a chain as the lifting mechanism, they are called pneumatic chain hoists. Likewise, when equipped with a wire rope as the lifting medium, they are called pneumatic wire rope hoists. These hoists are frequently used in environments which need electric spark avoidance because of a potentially explosive atmosphere.
Pneumatic press – It is a press which uses air or a gas to deliver the pressure to the upper and lower rams.
Pneumatics – It is an application of fluid power. It is the use of gas or pressurized air in mechanical systems. Pneumatic systems used in industry are commonly powered by compressed air or compressed inert gases. A centrally located and electrically-powered compressor powers cylinders, air motors, pneumatic actuators, and other pneumatic devices. A pneumatic system controlled through manual or automatic solenoid valves is selected when it provides a lower cost, more flexible, or safer alternative to electric motors, and hydraulic actuators. Pneumatics also has applications in construction, mining, and other areas.
Pneumatic shears – These are cutting tools powered by compressed air, designed for efficient and precise cutting of different materials like sheet metal, plastic, and rubber. They are normally used in industrial settings, automotive repair, and metal fabrication because of their speed and power. The cutting mechanism typically involves two blades powered by a pneumatic motor, which move rapidly back and forth when activated.
Pneumatic system – It is a system which uses compressed air to transmit and control energy. Pneumatic systems are used extensively in different industries. Pneumatic system is a collection of interconnected components using compressed air to do work for automated equipment. This work is produced in the form of linear or rotary motion. The compressed air or pressurized gas is normally filtered and dried to protect the cylinders, actuators, tools and bladders performing the work. Some applications need a lubrication device which adds an oil mist to the closed pressurized system. Majority of the pneumatic systems rely on a constant supply of compressed air to make them work. This is provided by an air compressor. The compressor sucks in air from the atmosphere and stores it in a high-pressure tank called a receiver. This compressed air is then supplied to the system through a series of pipes and valves.
Pneumatic tools – These are power tools driven by compressed air. They are used in different industries for their power, durability, and efficiency, especially in applications where electric tools are less suitable or where a high power-to-weight ratio is needed.
Pneumatic transport – It is also known as pneumatic conveying. It is a method of moving bulk materials like powders or granules through a pipeline using the flow of air or other gases. It is a common industrial process which relies on pressure differences or airflow to transport materials efficiently and reliably from one point to another.
Pnictogen – It consists of a chemical element belonging to Group (V) of the periodic table namely nitrogen, phosphorus, arsenic, antimony, bismuth, and moscovium. These elements are united by their common penta-valency, i.e., in their non-ionized states, atoms of these elements all have exactly five valence electrons in their outermost electron shell, three short of a complete octet.
P-N junction – It is a combination of two types of semiconductor materials, p-type and n-type, in a single crystal. The ‘n’ (negative) side contains freely-moving electrons, while the p (positive) side contains freely-moving electron holes. Connecting the two materials causes creation of a depletion region near the boundary, as the free electrons fill the available holes, which in turn allows electric current to pass through the junction only in one direction. p–n junctions represent the simplest case of a semi-conductor electronic device; a p-n junction by itself, when connected on both sides to a circuit, is a diode. More complex circuit components can be created by further combinations of p-type and n-type semi-conductors, e.g., the bipolar junction transistor (BJT) is a semi-conductor in the form n–p–n or p–n–p. Combinations of such semiconductor devices on a single chip allow for the creation of integrated circuits.
PNP transistor – It is a bipolar junction transistor (BJT) consisting of a thin layer of N-type semiconductor sandwiched between two P-type semiconductors. Its terminals are the emitter, base, and collector. In a PNP transistor, the central N-type layer is the base, while the two outer P-type layers serve as the emitter and collector. The primary charge carriers are holes (positive charges), and the transistor operates by allowing these holes to flow from the emitter to the collector when a negative voltage is applied to the base relative to the emitter.
Pocket – In a rolling-element bearing, it is the portion of the case which is shaped to receive the rolling element. It is also a body of sand surrounded on all but one side by molten metal.
Pocket-thrust bearing – It is an externally pressurized thrust bearing having three or more hydrostatic pads with central relieved chambers of pockets supplied with pressurized oil.
Pohland method – It is a technique for the ultrasonic testing of steel in which a visible image of the defects present in the steel can be shown on a screen.
Point – It is a microstructure-related defect. Point consists of vacancies both of interstitial and substitutional atoms. Because of this defective structure, there is inability of steel to achieve a desired microstructure and hence required microstructure related property during thermo mechanical processing.
Point analysis – It refers to methods which examine specific conditions or locations, such as detecting leaks by monitoring pressure at a single point in a pipeline, calculating the bias point of a circuit under steady-state conditions, or performing ‘function point analysis’ (FPA) to estimate software size and complexity based on user-requested functions.
Point angle – In general, it is the angle at the point of a cutting tool. Normally, it is the included angle at the point of a twist drill, the general-purpose angle being 118-degree.
Point bending – It refers to applying a force to a material or structure at a specific, concentrated point, or a small number of points, to induce bending and test its properties. Common examples are the three-point bending test and four-point bending test, which are used to determine a material’s flexural strength (its ability to resist bending), modulus of elasticity (stiffness), and flexural strain.
Point bending technique – It refers to methods like three-point bending and four-point bending, where a material or structure is supported and subjected to concentrated forces applied at specific points, mainly to determine its mechanical properties such as flexural strength, stiffness, and modulus of elasticity. These tests involve measuring the material’s response to these controlled forces to understand how it bends and ultimately fails.
Point concentrators – These refer to systems in concentrated solar power (CSP) technologies which utilize mirrors to focus sunlight onto a single point, typically to achieve high temperatures for heating a fluid. These concentrators can achieve temperatures very close to that of the sun.
Point defect – It is a type of crystal defect where there is an irregularity or imperfection at a single, specific point within the crystal lattice structure. These defects involve either missing atoms, extra atoms in interstitial positions, or impurities substituting for regular atoms. Point defects (as well as stationary dislocations, jogs, and kinks) present in a material create stress fields within a material that disallow traveling dislocations to come into direct contact. Much like two particles of the same electric charge feel a repulsion to one another when brought together, the dislocation is pushed away from the already present stress field.
Point estimate – It is the best single estimated value of a parameter. It is the estimate of a parameter given by a single statistic.
Point estimation – In statistics, it involves the use of sample data to calculate a single value (known as a point estimate since it identifies a point in some parameter space) which is to serve as a ‘best guess’ or ‘best estimate’ of an unknown population parameter (e.g., the population mean). More formally, it is the application of a point estimator to the data to obtain a point estimate.
Point of contact (POC) – It is sometimes called single point of contact (SPOC). Point of contact is a person or a department serving as the coordinator or focal point of information concerning an activity or program. A point of contact is used in many cases where information is time-sensitive and accuracy is important.
Point of sale (POS) – It is the physical or digital location where a customer completes a transaction by paying for goods or services. It is a system that includes hardware, like card readers and barcode scanners, and software to process payments, manage inventory, and generate invoices, facilitating the entire transaction process for both the customer and the organization.
Point-source pollution – It is the pollution which originates from one, easily identifiable cause or location, such as a sewage treatment plant.
Point to point (P2P) – It describes a circuit which connects two points directly, where there are normally no intermediate processing nodes, although there can be switching facilities.
Point to point protocol (PPP) – It is a data link layer (layer 2) communication protocol between two routers directly without any host or any other networking in between It can provide loop direction, authentication, transmission, and data compression.
Point to point (P2P) topology – It is a network topology which connects two nodes or devices directly using a dedicated line.
Poise (P) – It is the centimeter-gram-second (cgs) unit of dynamic viscosity.
Poisseuille (Pl) – It is the meter-kilogram-second (mks) or International System of Units (SI) unit of dynamic viscosity. 1 Poisseuille is equal to 10 Poise.
Poiseuille flow – It is the particular case of laminar viscous flow through a long pipe of circular cross section.
Poison – It is a chemical substance which is harmful or lethal to living organisms. The term is used in a wide range of industries, where it is frequently specifically defined. Whether something is considered a poison or not can depend on the quantity, the circumstances, and what living things are resent. Poisoning can be accidental or deliberate, and if the cause can be identified there can be ways to neutralize the effects or minimize the symptoms.
Poisson bracket – In Hamiltonian mechanics, it is a mathematical operation which defines a relationship between two functions (frequently representing dynamical variables) of a system’s phase space. It is a binary operation, meaning it takes two inputs and produces one output. This output, the Poisson bracket, essentially describes how the first function evolves with time under the influence of the second function (frequently the Hamiltonian, which represents the total energy of the system).
Poisson burr – It is a burr which is formed predominantly by the phenomenon that is responsible for Poisson’s ratio. It is sometimes called a flow-type burr. Poisson burr is a type of burr (a raised edge or small piece of material) which forms because of the material’s lateral deformation during machining, particularly when a cutting tool compresses the material sideways. This phenomenon is named after the Poisson effect, which describes a material’s tendency to expand perpendicularly to the direction of compression.
Poisson contraction – It is also known as the Poisson effect. It describes the phenomenon where a material, when stretched or compressed in one direction, tends to contract or expand, respectively, in the perpendicular directions. This is a consequence of the material’s Poisson’s ratio, which quantifies this relationship between strains in different directions.
Poisson distribution – It is a probability distribution for an integer variable representing an event count. The Poisson distribution is frequently referred to as the distribution of rare events. It is typically used to describe the probability of occurrence of an event over time, space, or length. In general, the Poisson distribution is appropriate when such conditions hold as the probability of ‘success’ in any given trial is relatively small, the number of trials is large, and the trials are independent.
Poisson effect – It describes the phenomenon where a material deforms in directions perpendicular to the applied force. When a material is compressed, it tends to expand in the directions perpendicular to the compression. Conversely, when stretched, it tends to contract in the transverse directions.
Poisson process – It is a fundamental stochastic model which describes the occurrence of random, independent events over time or space at a constant average rate. It is characterized by (i) no events at time zero, (ii) independent increments (events in one time interval don’t affect another), and (iii) stationary increments (the probability of an event depends only on the length of the interval, not when it occurs). Engineers use it for modeling random phenomena like component failures, customer arrivals at a service point, or data requests in a network.
Poisson’s ratio – It is the absolute value of the ratio of transverse (lateral) strain to the corresponding axial strain resulting from uniformly distributed axial stress below the proportional limit of the material.
Poisson regression – It is a type of regression analysis in which the study end point is a count of the number of occurrences of an event which has happened to subjects in some fixed period of time.
Polar boss – In filament winding, it is a metal end fitting located in the center of each dome that describes the pole about which winding bands are wrapped.
Polar winding – It is a winding in which the filament path passes tangent to the polar opening at one end of the chamber and tangent to the opposite side of the polar opening at the other end. A one-circuit pattern is inherent in the system.
Polaris membrane – It is a proprietary, carbon di-oxide-selective polymeric membrane developed by MTR Industrial Separations which achieves considerably higher carbon di-oxide permeance (flow rate) and selectivity compared to conventional membranes, allowing for more efficient capture of carbon di-oxide from industrial gas streams, such as syngas and post-combustion flue gas, without the need for chemical solvents or high-temperature heat.
Polarity – It is a separation of electric charge leading to a molecule or its chemical groups having an electric dipole moment, with a negatively charged end and a positively charged end. In welding, it consists of direct current electrode negative and direct current electrode positive. In case of direct current electrode negative, 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. It is also referred to as straight polarity. In case of direct current electrode positive, it is the arrangement of direct current arc welding leads in which the work is the negative pole and the electrode is the positive pole of the welding arc.
Polarity gap – It is the difference in charge-transfer properties (tribo-electric polarity) between two materials, which is important for optimizing tribo-electric nano-generators (TENGs) by improving their output performance. It is also the difference in voltage needed to cause breakdown in an electrical gap with either a positive or negative electrode, which is influenced by space charge effects and is a critical parameter for designing electrical equipment operating in high-voltage conditions.
Polarity reversal – It is the process of flipping the north and south poles of a magnetic field or the positive and negative terminals of an electrical current, causing a change in direction. This term is very frequently used in geology to describe the earth’s magnetic field flipping, but can also refer to reversing electrical current in power systems, switching electrodes in welding, or reversing the direction of direct current motors.
Polarization – It is the change from the open-circuit electrode potential as the result of the passage of current. It is a change in the potential of an electrode during electrolysis, such that the potential of an anode becomes more noble, and that of a cathode more active, than their respective reversible potentials. It is equal to the difference between the static electrode potential and the dynamic electrode potential. It is frequently accomplished by formation of a film on the electrode surface.
Polarization admittance – It is the reciprocal of polarization resistance.
Polarization curve – It is a plot of current density against electrode potential for a specific electrode-electrolyte combination.
Polarization density – It is a measure of the increase of the intensity of an electric field over that in free space, owing to the separation of atomic-scale electric dipoles.
Polarization field – It is also called polarization vector. It refers to the dipole moment per unit volume within a dielectric material caused by an external electric field. It describes the alignment and displacement of charges within the material, leading to an internal electric polarization which opposes and reduces the external field. The polarization field is a measure of how strongly a material is polarized and is expressed in units of coulombs per square meter.
Polarization resistance – It is the slope at the corrosion potential of a potential / current density curve. It is also used to describe the method of measuring corrosion rates using these slopes.
Polarized light – Polarized light, as used in metallography, has normally been limited to observation of certain optically anisotropic metals, such as beryllium, alpha-titanium, zirconium, and uranium, which are difficult to etch but respond well to the polarized light when properly polished. Before development of the electron micro-probe analyzer (EMPA) and energy dispersive spectroscopy (EDS), polarized light examination was an integral part of the method for identifying inclusions. Since the development of these instruments, polarized light has been used less frequently for this purpose, since identification with the electron micro-probe analyzer or energy dispersive spectroscopy techniques is more definitive. Majority of the metallurgical microscopes now use synthetic Polaroid filters. The ‘polarizer’ is placed in the light path before the objective, and the ‘analyzer’ is placed in the light path after the objective, normally just below the eyepiece.
Polarized light microscopy – It consists of a number of optical microscopy techniques involving polarized light. Simple techniques include illumination of the sample with polarized light. Directly transmitted light can, optionally, be blocked with a polarizer oriented at 90-degree to the illumination. More complex microscopy techniques which take advantage of polarized light include differential interference contrast microscopy and interference reflection microscopy. Frequently a device called a polarizing plate is used to convert natural light into polarized light. These illumination techniques are normally used on birefringent samples where the polarized light interacts strongly with the sample and so generating contrast with the background. Polarized light microscopy is used extensively in optical mineralogy.
Polarized optical microscope – It is a specialized microscope which uses polarized light to observe and analyze the internal structure and optical properties of materials, particularly anisotropic ones like polymers, ceramics, and crystals. It uses a polarizer and an analyzer to interact with the sample’s birefringence, or double refraction, revealing its molecular alignment, crystal orientation, and micro-structure to provide insights into material properties, defects, and degradation.
Polarizing element – It is a general term for a device for producing or analyzing plane-polarized light. It can be a Nicol prism, some other form of calcite prism, a reflecting surface, or a polarizing filter.
Polar moment of inertia – It is the moment of inertia where the distance is measured from an axis perpendicular to the plane of the area.
Polarography – It is an electro-analytical technique in which the current between a dropping mercury electrode (DME) and a counter-electrode (both of which are immersed in electrolyte) is measured as a function of the potential difference between the dropping mercury electrode and a reference electrode.
Pole – It is a structural element such as a utility pole used for distributing power lines. It is also a mathematical concept in control systems and signal processing representing frequencies where a system’s transfer function becomes infinite, hence influencing system stability and dynamic response. Pole also refers to the geographic centre of a spherical mirror’s reflecting surface. Pole also refers to one of the two extreme points of a physical object or a system, frequently characterized by opposite properties or actions. Common examples include the North and South Poles on a magnet or the earth, where magnetic field lines emerge or converge, and the poles of a battery, which are the points of positive and negative electrical charge. Pole is also a means of designating the orientation of a crystal plane by stereographically plotting its normal. For example, the north pole defines the equatorial plane. It is either of the two regions of a permanent magnet or electro-magnet where most of the lines of induction enter or leave.
Pole figure – It is a stereoscopic projection of a poly-crystalline aggregate showing the distribution of poles, or plane normal, of a specific crystalline plane, using sample axes as reference axes. Pole figures are used to characterize preferred orientation in poly-crystalline materials.
Pole piece – It is a structure composed of material of high magnetic permeability which serves to direct the magnetic field produced by a magnet. A pole piece attaches to and in a sense extends a pole of the magnet, hence the name. Pole pieces are used with both permanent magnets and electromagnets. In the case of an electromagnet, the pole piece or pieces simply extend the magnetic core and can even be regarded as part of it, particularly if they are made of the same material. In the case of a permanent magnet, the distinction between the magnet itself and the pole piece or pieces is more-clear cut.
Pole pitch – It refers to the distance between the centres of two adjacent poles in a magnetic field, frequently influencing the design of components such as the pole shoes in a permanent magnet generator to improve output voltage wave-form and reduce electrical noise.
Policy – It is a governing principle, plan, or consistent course of action developed in order to meet recognized needs and to achieve specific measurable outcomes. Policies are normally broad, conceptual documents which outline approaches and / or considerations to be taken into account by decision makers. Policies do not act as constraints, but provide information. Policy is also a statement of intent which is not legally binding. It sets direction and expectations for activities.
Policy analysis – It is the comparison of the viability and effects of an existing or proposed set of operating rules to the impact of some other option.
Policy base – It is a fundamental layer or system of rules which governs the behaviour of another system, providing a set of principles for decision-making and management. In short, it is a defined collection of policies which serve as the foundation or operating framework for network management, data management, access control, and other areas, enabling flexibility, automation, and adherence to specific goals.
Policy control – It is the process of creating, implementing, and enforcing policies to manage and govern the behaviour of a system or network, frequently by defining rules and conditions for access, resource allocation, or service quality. It ensures that actions and resource usage align with predefined objectives, like those in network resource management (e.g., Quality of Service and gating) or security (e.g., policy-based access control), by specifying how, when, and by whom resources can be accessed or used.
Policy decision – It is a deliberate, high-level choice made by an individual or organization to guide future actions and achieve specific objectives, establishing a consistent approach to addressing an issue or set of principles. These decisions are frequently value-loaded and consider potential outcomes, resource implications, and underlying assumptions, forming a coherent framework to be implemented as procedures or protocols.
Policy deployment – It is frequently known as Hoshin Kanri. It is a management process that translates a company’s high-level strategic goals into specific, actionable policies and tasks that are understood and pursued by every level of the organization. It uses systematic planning, communication, and review to align everyone towards common objectives, ensuring that daily work supports the long-term strategy and fosters continuous improvement.
Policy development – It is the process of shaping policy, from issue recognition and analysis to implementation and evaluation. Organizational management role is to undertake the necessary steps to develop policy options as well as to decide policy.
Policy instruments – These are tools, techniques, or mechanisms used by authorities to implement policies and achieve specific goals or solve problems within society, the economy, or the environment. These tools are basically the ‘how’ of governance, linking policy goals to practical outcomes through different interventions, such as laws, financial incentives, information campaigns, or direct government action.
Policymakers – They are the individuals or entities responsible for creating and implementing policies, needing collaboration with different stakeholders such as financial institutions, government ministries, and commercial bankers to ensure effective governance and project development.
Polished surface – It is a surface which is prepared for metallographic inspection that reflects a large proportion of the incident light in a specular manner.
Polishing – It is the smoothing of metal surfaces, frequently to a high lustre, by rubbing the surface with a fine abrasive, normally contained in a cloth or other soft lap. It is the results in microscopic flow of some surface metal together with actual removal of a small quantity of surface metal. It is the removal of material by the action of abrasive grains carried to the work by a flexible support, normally either a wheel or a coated abrasive belt. It is also a mechanical, chemical, or electrolytic process or combination thereof used to prepare a smooth, reflective surface suitable for microstructural examination that is free of artifacts or damage introduced during prior sectioning or grinding.
Polishing machine – It is a device which utilizes fine particle abrasives and soft pads to produce mirror-like surfaces through sliding friction between the abrasives and the treated surface, frequently used in surface preparation for further treatments.
Polishing pond – It is the last in a series of settling ponds through which plant effluent flows before being discharged into the natural environment.
Polishing process – It uses mechanical, chemical, or electrochemical effects to reduce a material’s surface roughness, creating a smooth, bright, and reflective finish by removing imperfections like scratches and marks. It involves using abrasive tools and media to wear down peaks and valleys on the surface, progressing from coarse to fine materials for optimal results. After polishing, surfaces are frequently cleaned to maintain their reflective properties.
Polishing wear – It is an extremely mild form of wear for which the mechanism has not been clearly identified, but that can involve extremely fine-scale abrasion, plastic smearing of micro-asperities, and / or tribo-chemical material removal.
Pollutant – It is a contaminant in a concentration or quantity which adversely alters the physical, chemical, or biological properties of the natural environment.
Pollutant gas – It is a harmful gaseous substance, such as carbon mono-oxide (CO) or sulphur di-oxide (SO2), released into the environment by natural or human activities (like industrial processes) which can negatively affect environmental quality and human health. These harmful gases can be main pollutants, emitted directly into the atmosphere, or secondary pollutants, formed from the reaction of main pollutants with other atmospheric components.
Pollutant load – It is the quantity of pollutant entering an environment. Loads are normally expressed in terms of a weight and a time frame, such as kilograms per day.
Pollutant removal – It is the process of eliminating or significantly reducing harmful substances from the environment, such as air, water, or soil, to improve environmental quality and protect public health and ecosystems. This reduction is achieved through several techniques and technologies designed to separate pollutants from their carrying medium, such as physical filtration, chemical reactions, or biological degradation, ensuring compliance with environmental standards and promoting sustainability.
Polluted air – It is the air which has become contaminated with harmful gases, dust, smoke, chemicals, or other particulate matter that alters its natural characteristics and makes it unsafe for living beings to breathe. These pollutants, which can originate from natural events like volcanic eruptions or human activities such as industrial processes, pose substantial health risks to humans and animals and can also damage ecosystems and infrastructure.
Polluting emission – it is a substance, frequently a gas or particle, released into the environment which has a negative impact on human health, the ecosystem, or the climate. These harmful emissions originate from both natural and human-made sources, such as industrial processes, vehicle exhaust, volcanic activity, and wildfires. Common examples include carbon di-oxide (CO2), nitrogen oxides (NOx), sulphur di-oxide (SO2), particulate matter (PM), and volatile organic compounds (VOCs), which contribute to problems like acid rain, smog, and respiratory illnesses.
Pollution – It is the introduction of harmful materials into the environment. These harmful materials are called pollutants. Pollutants can be natural, such as volcanic ash. They can also be created by human activity, such as trash or runoff produced by industrial activities. Pollutants damage the quality of air, water, and land.
Pollution abatement – It consists of the technology applied or measure taken to reduce pollution and / or its impacts on the environment. The normally used technologies are scrubbers, noise mufflers, filters, incinerators, waste-water treatment facilities and composting of wastes.
Pollution control – It refers to the scientific methods and techniques which are used to manage and reduce pollution in the environment, aiming to protect human health and eco-systems.
Pollution control device (PCD) – It is any system, equipment, or process designed to capture, reduce, convert, or eliminate pollutants from their source, such as industrial smokestacks or vehicle exhausts, before they enter the environment. These devices are necessary for improving air and water quality, protecting public health, achieving regulatory compliance, and preventing ecological damage by removing or mitigating harmful particulate matter, gases, and other emissions.
Pollution prevention – It means working at the source of pollutants to prevent them from being generated or to reduce the amount generated.
Polyacetals – These are also known as acetal resins or poly-oxy-methylene (POM). These are a family of engineering thermoplastics known for their high strength, stiffness, excellent dimensional stability, and good lubricity, making them suitable for precision mechanical parts. They are characterized by an oxygen-containing functional group in their polymer chain, formed from formaldehyde and often stabilized to prevent degradation.
Polyacrylates – These are synthetic resins produced by the polymerization of acrylic esters. Forming plastic materials of notable clarity and flexibility under certain methods, the polyacrylates are used mainly in paints and other surface coatings, in adhesives, and in textiles. The most common poly-acrylates are polyethyl acrylate and polymethyl acrylate.
Polyacrylo-nitrile (PAN) – It is a synthetic, semi-crystalline organic polymer resin, with the linear formula (CH2CHCN)n. Almost all poly-acrylo-nitrile resins are copolymers with acrylonitrile as the main monomer. Poly-acrylo-nitrile is used to produce large variety of products including ultra filtration membranes, hollow fibres for reverse osmosis, fibres for textiles, and oxidized poly-acrylo-nitrile fibres. Poly-acrylo-nitrile fibres are the chemical precursor of very high-quality carbon fibre. Poly-acrylo-nitrile is first thermally oxidized in air at 230 deg C to form an oxidized poly-acrylo-nitrile fibre and then carbonized above 1,000 deg C in inert atmosphere to make carbon fibres found in a variety of both high-tech and common daily applications.
Polyalkylene glycol (PAG) – It consists of a range of ethylene oxide and propylene oxide derivatives built off different initiators, giving a product family with a wide range of solubility and viscosity properties. Poly-alkylene glycol is versatile polymers which are widely used across a range of industries.
Polyalkylene oxides – These also known as polyethers. These are a class of versatile polymers formed by repeating units of alkylene oxides, such as ethylene oxide and propylene oxide. They are used in a variety of applications, including lubricants, and as stabilizers for organic materials like wood. Key examples include polyethylene glycol, which is highly water-soluble, and polypropylene oxide, which is water-insoluble but flexible.
Polyalpha-olefin (PAO) – It is a synthetic hydrocarbon (SHC) and the most common synthetic base oil used in industrial and automotive lubricants, created by polymerizing alpha-olefins. Polyalpha-olefins mimic the hydrocarbon structure of mineral oils but offer superior properties such as higher thermal stability, a high viscosity index, and excellent low-temperature performance. They are produced from ethylene and are used in engine oils, hydraulic fluids, compressor oils, and several industrial applications.
Polyalpha-olefin (PAO) oil – It is a synthetic oil that is produced by alpha-olefin monomers. It is characterized by its high purity, pour-point characteristics. Poly-alpha-olefins are used in lubricants which have to meet the highest requirements, e.g., in applications with large temperature fluctuations.
Polyamide – It is a thermoplastic polymer in which the structural units are linked by amide or thio-amide groupings (repeated nitrogen and hydrogen groupings). Several polyamides are fibre-forming.
Polyamideimide – It is a polymer containing both amide (nylon) and imide (as in polyimide) groups. Its properties combine the benefits and disadvantages of both.
Polyamide plastic – These are plastics which are based on a resin composed principally of a long-chain synthetic polymeric amide which has recurring amide groups as an integral part of the main polymer chain. Numerical designations (nylon 6, nylon 6/6, and so on) refer to the monomeric amides of which they are made. This plastic is characterized by high toughness and elasticity.
Polyamide resins – Polyamide materials can be categorized by their temperature capabilities into those with an upper limit of 230 deg C for extended time periods, and those capable of extended use up to 315 deg C. Bismaleimides, phenyl-ethynyl-containing polyimides, and some condensation polyimides such as Avimid-K3 belong in the former category, while those materials such as PMR-15, LARC-TPI, Avimid-N and BPDA/TFMB belong in the latter. In terms of chemistry, there are two general types of commercial polyimides namely thermoplastic polyimides, derived from a condensation reaction between anhydrides or anhydride derivatives and diamines, and cross-linked polyimides, derived from an addition reaction between unsaturated groups of a preformed imide monomer or oligomer. The imide monomers or oligomers are also derived from the typical condensation reaction to form the imide group, but polymer formation stems from the addition reaction.
Polyaniline – It is a versatile and environmentally stable conductive polymer known for its high electrical conductivity, ease of synthesis, and ability to be doped with acids. It shows unique electrochemical properties, is lightweight and flexible, and finds diverse applications in sensors, optoelectronic devices, corrosion protection, and energy storage devices like supercapacitors and batteries. Despite its advantages, it can have poor mechanical properties and processability, which is frequently addressed by creating composites with other materials.
Polyaromatics – These are more formally known as polycyclic aromatic hydrocarbons (PAHs). These are organic compounds consisting of two or more fused aromatic rings, typically benzene rings, containing only carbon and hydrogen atoms. They are found in different forms and arrangements and are known environmental pollutants and carcinogens, produced by incomplete combustion of organic matter from sources like fossil fuels.
Polyarylate – It is an amorphous, high-performance thermoplastic polymer in the family of aromatic polyesters, formed by linking aromatic dicarboxylic acids and aromatic dihydroxy compounds (diphenols). Key characteristics include high strength, toughness, excellent thermal stability, and good resistance to ultraviolet (UV) light, making them suitable for demanding applications like automotive parts and electronic devices.
Polyaryletherketone (PAEK) – It is a family of high-performance, semi-crystalline thermoplastic polymer known for excellent high-temperature stability, mechanical strength, chemical resistance, and bio-compatibility. The family includes PEEK (polyetheretherketone) and PEKK (polyetherketoneketone), among others, differentiated by the ratio and arrangement of their alternating aromatic, ether, and ketone functional groups. These durable materials are widely used in demanding fields like aerospace, and automotive components.
Polyarylsulfone (PAS) – It is a high-temperature-resistant thermoplastic with ‘Tg’ (glass transition temperature) values ranging from 190 deg to 275 deg C. The term is also occasionally used to describe the family of resins which includes polysulfone and polyethersulfone.
Polyatomic – It is composed of two or more atoms, of the same or different elements.
Polyatomic ion – It is a molecule which is composed of two or more covalently bonded atoms which collectively bear a net electric charge and therefore act as an ion.
Polybenzimidazole (PBI) – It is a condensation polymer of diphenyl isophthalate and 3,3’- diaminobenzidine. It is extremely high-temperature resistant. It is available as adhesive and fibre.
Polybutadiene (PB) rubber – It is a synthetic rubber. It offers high elasticity, high resistance to wear, good strength even without fillers, and excellent abrasion resistance when filled and vulcanized. ‘Polybutadiene’ is a collective name for homopolymers formed from the polymerization of the monomer 1,3-butadiene. The International Union of Pure and Applied Chemistry (IUPAC) refers to polybutadiene as ‘poly(buta-1,3-diene)’. Historically, an early generation of synthetic polybutadiene rubber produced in Germany by Bayer using sodium as a catalyst was known as ‘Buna rubber’. Polybutadiene is typically crosslinked with sulphur. However, it has also been shown that it can be ultra violet cured when bis-benzophenone additives are incorporated into the formulation.
Polybutylene terephthalate (PBT) – It is a thermoplastic engineering polymer which is used as an insulator in the electrical and electronics industries. It is a thermoplastic (semi-)crystalline polymer, and a type of polyester. Poly-butylene terephthalate resists solvents, shrinks very little during forming, is mechanically strong, is heat-resistant up to 150 C (or 200 deg C with glass-fibre reinforcement), and can be treated with flame retardants to make it non-combustible. Poly-butylene terephthalate is closely related to other thermoplastic polyesters. Compared to polyethylene terephthalate (PET), poly-butylene terephthalate has slightly lower strength and rigidity, slightly better impact resistance, and a slightly lower glass transition temperature.
Polycarbonate (PC) – It is a thermoplastic polymer which is derived from the direct reaction between aromatic and aliphatic dihydroxy compounds with phosgene, or by the ester exchange reaction with appropriate phosgene-derived precursors. It has highest impact resistance of any transparent plastic.
Polycarbonate polyol – It is a polyol (a molecule with multiple hydroxyl groups) which contains a carbonate group in its molecular backbone, which can be derived from the reaction of a diol with a carbonate or phosgene. These polyols are used as a component in polyurethane formulations, providing improved performance characteristics such as high impact resistance, flexibility, hydrolysis resistance, and sustainability by sequestering carbon di-oxide directly into their structure.
Polycarboxylate – It is an organic compound characterized by a carbon-carbon backbone with multiple carboxylic acid groups (-COOH) attached, making it a polymer. The term frequently refers to specific types of polymers like polycarboxylate superplasticizers used in concrete, which are ‘comb-shaped’ with a primary backbone and pendant polyethylene glycol chains. However, it can also refer to water-soluble polymers, such as those derived from acrylic acid and maleic acid.
Polycarboxylic acid (PCA) – It is an organic compound containing two or more carboxyl groups (-COOH) per molecule. These compounds have diverse applications, including being used as textile finishing agents, water treatment chemicals to inhibit scale formation, and complexing agents in chemical applications.
Polychlorinated bi-phenyls (PCBs) – These are organochlorine compounds with the formula C12H(10-x)Clx. They have been once widely used in the manufacture of carbonless copy paper, as heat transfer fluids, and as dielectric and coolant fluids for electrical equipment. They are highly toxic and carcinogenic chemical compounds, formerly used in industrial and consumer electronic products, whose production has been banned internationally by the Stockholm Convention on Persistent Organic Pollutants in 2001.
Polychloroprene (PCP) – It is also known as Neoprene. It is a synthetic rubber made by polymerizing chloroprene. It is known for its good chemical stability and flexibility across a wide temperature range. PCP is used in several applications, including cable sheathing.
Polychloroprene rubber – It is commercially known as neoprene. It is defined as a special purpose rubber which is structurally similar to isoprene, with chlorine atoms replacing methyl groups, providing properties such as heat and ozone stability, fire retardancy, and high mechanical strength.
Polychromator – It is an optical device which is used to disperse light into different directions to isolate parts of the spectrum of the light. A prism or diffraction grating can be used to disperse the light. Unlike a mono-chromator, it outputs multiple beams over a range of wave-lengths simultaneously. Mono-chromators have one exit slit and one wave-length at a time can pass through that slit. Poly-chromators have multiple exit slits, each of which allows a different wavelength to pass through it. A detector is placed after each slit so that the light at each wave-length is measured by a different detector. Poly-chromators are frequently used in spectroscopy.
Polycondensation – It is a chemical reaction in which two or more molecules combine, with the separation of water or some other simple substance. If a polymer is formed, the process is called polycondensation.
Polycondensation reaction – It is a step-growth polymerization process where monomers with two or more reactive functional groups link together to form a long polymer chain, with the simultaneous elimination of small molecules, such as water or alcohol. This reaction forms polymers like polyesters, polyamides, and polyurethanes, and it requires the effective removal of these byproducts to drive the reaction forward to produce high-molecular-weight polymers.
Polycrystal – It is a solid material composed of several smaller, individual crystals called grains, which are separated by regions called grain boundaries. These grains typically have different crystallographic orientations, though their size can vary greatly. The presence of grain boundaries, where atomic packing is less ordered, influences the material’s physical properties, making it a common structure in several natural and synthetic materials like metals, ceramics, and solar panels.
Polycrystalline – It is pertaining to a solid comprised of many crystals or crystallites, intimately bonded together. It can be homogeneous (one substance) or heterogeneous (two or more crystal types or compositions).
Polycrystalline alumina (PCA) – It is a ceramic material composed of aluminum oxide (Al2O3) which is formed by multiple, small crystal grains, rather than a single large crystal. Its physical properties, such as strength, transparency, and dielectric strength, are influenced considerably by its microstructure, specifically the size of these grains and the presence of pores. While inherently an electrical insulator, its microstructure can be optimized through techniques like doping and controlled sintering to achieve properties suitable for high-performance applications, such as transparent armour, and high-voltage insulation.
Polycrystalline cast superalloys – These are superalloys which are a group of nickel-iron-nickel-, and cobalt-base materials. These superalloys show outstanding strength and surface stability at temperatures up to 85 % of their melting points (0.85 Tm). They are normally used at temperatures above 540 deg C compositions.
Polycrystalline ceramics – These are nonmetallic, inorganic materials composed of many small, densely packed crystal grains (or crystallites) with a random crystallographic orientation and no glassy phase. Their microstructure of interlocking crystals leads to high strength, hardness, and fracture toughness by hindering crack propagation, making them suitable for applications requiring high mechanical performance
Polycrystalline cubic boron nitride (PcBN) – It is the second hardest material after diamond. It is used as a cutting material from which indexable inserts are manufactured for machining. It is produced synthetically and is a composite material made of cubic boron nitride and a mostly ceramic binder phase. The ratio of cubic boron nitride to binder content and the cubic boron nitride grain size determines the application. Polycrystalline cubic boron nitride cutting materials are used in the machining of hard and / or highly abrasive workpiece materials. The high hardness and the extremely high hot hardness (up to temperatures above 1,000 deg C), the edge stability and inertness towards ferrous materials as well as the basically good chemical resistance give cubic boron nitride cutting materials a high potential for use in machining.
Polycrystalline diamond – It is a composite comprising diamond particles, which are formed by sintering together with a metallic binder.
Polycrystalline material – It is a solid composed of several tiny, randomly oriented single crystals, or grains, separated by grain boundaries. Each grain has a consistent internal crystal structure, but the orientations of the grains are different from one another. This arrangement influences the material’s overall physical properties, such as strength, hardness, and optical or electrical behaviour, which depend on the size and characteristics of these grains and boundaries.
Polycrystalline metal – It is a solid metal composed of many tiny, randomly oriented single crystals, or grains, which are bonded together at their boundaries. These grains all have the same crystal structure but differ in their crystallographic orientation, with the grain boundaries influencing the material’s overall properties, such as its strength and hardness. Several common engineering metals, like stainless steel, are polycrystalline.
Polycrystal scattering topography (PST) – It is a new kind of X-ray topography which has been devised to observe polycrystalline, amorphous materials. In this method, X-ray is scattered from a poly-crystal produce a topographical image. Poly-crystal scattering topography enables, in principle, to make tomographic observations.
Polycyclic aromatic hydrocarbons (PAHs) – These are hydrocarbons with two or more benzene rings formed by the incomplete combustion of organic materials such as wood, coal, and refuse. They are found in petroleum products and creosote and include such compounds as naphthalene, anthracene, and benzo-a-pyrene. When carried in water, they can pose a threat to human health and aquatic life.
Polydimethylsiloxane (PDMS) – It is a silicon-based organic polymer known for its optically transparent, inert, nontoxic, and inflammable properties, and is widely used because of its rheological characteristics. It is obtained from the hydrolysis of dimethyldichlorosilane.
Polydispersity – It describes the degree of non-uniformity in particle sizes or molecular weights within a sample, particularly common in polymer and nano-particle systems. It is quantified by the polydispersity index (PDI), which is a ratio of a higher-average value to a lower-average value (e.g., weight-average molecular weight to number-average molecular weight for polymers). A polydispersity index closer to 0 indicates a uniform, mono-disperse sample, while a polydispersity index closer to 1 signifies a broad, polydisperse distribution.
Polydispersity index (PDI) – It is also known as dispersity (Đ). It is a measure of the heterogeneity of a sample’s size distribution or molecular weight distribution. A polydispersity index value of 0 indicates a perfectly mono-disperse (uniform) sample, while higher polydispersity index values (closer to 1 or even higher) indicate a broader, more polydisperse (non-uniform) distribution of sizes or molecular weights. This value is important in fields like polymer science and nano-particle analysis to understand the variability within a sample.
Polyelectrolyte membrane – It is a membrane composed of polyelectrolytes, which are water-soluble polymers with several charged functional groups. These membranes are frequently created using the layer-by-layer (LbL) technique, where oppositely charged polyelectrolyte layers are sequentially deposited onto a support. They are designed for selective ion transport and separation applications, such as in fuel cells, water treatment, and other filtration processes, with their properties influenced by the types of polyelectrolytes used, their molecular weight, and the number of deposited layers.
Polyepoxy – It is a compound or polymer which contains multiple reactive epoxide (or oxirane) groups, which are three-membered rings with one oxygen atom. These compounds, also known as epoxy resins or polyepoxides, are typically two-part systems consisting of a resin and a hardener (or crosslinker) which react chemically to form a strong, rigid, three-dimensional thermosetting polymer with excellent adhesion, chemical, and mechanical properties.
Polyester – It is low-elongation fibre which is normally used as belt warp. It has almost no moisture absorption, and good dimensional stability.
Polyester diol – It is an aliphatic polyester (a type of polyol) formed by the reaction of a dibasic acid and a glycol, resulting in a polymer with multiple hydroxyl (-OH) groups. These hydroxy-terminated polymers serve as essential base materials for manufacturing durable polyurethane products used in applications such as adhesives, coatings, and flexible foams.
Polyester fibre – It is a man-made, petroleum-based synthetic fiber formed from the polymerization of long-chain polymers, primarily polyethylene terephthalate (PET). It is produced by melting polyester pellets and extruding the liquid through small holes to form strings, which are then woven into durable, resilient, and wrinkle-resistant fabrics. It is used in a wide array of applications, including clothing, home furnishings, and industrial products, polyester fibres are known for their strength, shape retention, and quick-drying properties, though they contribute to microplastic pollution during washing.
Polyester polymer – It is a synthetic polymer containing ester functional groups (-CO-O-) in its molecular backbone. These polymers are formed through condensation reactions, typically between a dicarboxylic acid and a diol, and exist as long chains of repeating units. Common polyesters include polyethylene terephthalate (PET), used in bottles and textiles, and they are utilized in applications from packaging to engineering devices.
Polyester polyols – These are polymers containing both hydroxyl (-OH) and ester (R-COO-R’) groups, formed by the condensation reaction of dicarboxylic acids with polyols (like glycols or tri-methylol-propane) or lactone polymerization. These versatile compounds are key components in producing polyurethanes, where their ester groups provide high adhesion, strength, wear resistance, and chemical stability, making them ideal for coatings, foams, and elastomers.
Polyester resins – These are unsaturated polyester resins. These resins are the group of polyesters in which the acid component part of the ester is partially composed of fumaric acid, a 1,2-ethylenically unsaturated material. Maleic anhydride is the predominant source of this fumarate. Maleic anhydride is incorporated into the polyester backbone and then isomerized to provide fumarate esters (commonly referred to as unsaturated polyesters).
Polyesters – Polyesters are macro-molecules which are prepared by the condensation polymerization of difunctional acids or anhydrides with difunctional alcohols or epoxy resins. Polyesters have high strength, exceptionally good abrasion, and fatigue resistance. They have extremely low moisture absorption and hence have good dimensional stability. They are unaffected by mildew.
Polyesters, thermoplastic – These are a class of thermoplastic polymers in which the repeating units are joined by ester groups. The two important types are (i) polyethylene terephthalate (PET), which is widely used as film, fibre, and soda bottles, and (ii) polybutylene terephthalate (PBT), mainly a moulding compound.
Polyesters, thermosetting – These are a class of resins produced by dissolving unsaturated, normally linear, alkyd resins in a vinyl-type active monomer such as styrene, methyl styrene, or diallyl phthalate. Cure is carried out through vinyl polymerization using peroxide catalysts and promoters or heat to accelerate the reaction. The two important commercial types are (i) liquid resins which are cross linked with styrene and used either as impregnants for glass or carbon-fibre reinforcements in laminates, filament-wound structures, and other built-up constructions, or as binders for chopped-fibre reinforcements in moulding compounds, such as sheet moulding compound (SMC), bulk moulding compound (BMC), and thick moulding compound (TMC), and (ii) liquid or solid resins cross linked with other esters in chopped-fiber and mineral-filled moulding compounds, for example, alkyd and diallyl phthalate.
Polyester urethane – It is a type of polyurethane created using a polyester polyol, which gives it superior sliding abrasion and chemical resistance compared to polyether-based polyurethanes. It is a versatile material known for its elasticity and used in applications like chute liners, wear pads, and high-quality, durable product finishes that require resistance to weathering.
Polyether ether ketone (PEEK) – It is a special polymer material which is composed of repeated units of one ketone bond and two ether bonds in the backbone of the aromatic ring. It is a semi-crystalline, linear, and aliphatic polymer. It is a colourless organic thermoplastic polymer which is used in engineering applications. It has a high melting point of 334 deg C. A composite with a polyether ether ketone matrix can have a continuous use temperature as high as 250 deg C.
Polyether-imide – It is an amorphous engineering thermoplastic. It has a number of desirable properties including a high heat-distortion temperature. Poly-ether-imide has reported ‘Tg’ of 215 deg C and continuous-use temperature of around 170 deg C. Unlike majority of the amorphous resins, poly-ether-imide is resistant to a wide range of chemicals including most hydrocarbons, alcohols, and fully halogenated solvents. Only partially halogenated hydrocarbons such as methylene chloride and tri-chloro-ethane dissolve polyetherimide, and these compounds are not to be used for cleaning.
Polyether-ketones – These are polymers whose molecular backbone contain alternating ketone (R-CO-R) and Ether (R-O-R) functionalities. The most common are Poly-aryl-ether-ketones, in which there is an aryl group linked in the (1–4)-position between each of the functional groups. The backbone, which is hence very rigid, gives the materials very high glass transition and melting temperatures compared to other plastics.
Polyether-sulfones (PES) – These are a class of engineered polymers with very high thermal oxidative resistance, hydrolytic stability and excellent strength and flexibility. They are amorphous, transparent thermoplastics which can be moulded, extruded, or thermoformed into a wide variety of shapes. The backbone flexibility of this polymer is provided by ether linkages.
Polyethylene – It is the most produced plastic. It is a polymer, mainly used for packaging. Several kinds of poly-ethylene are known, with most having the chemical formula (C2H4)n. Polyethylene is normally a mixture of similar polymers of ethylene, with various values of ‘n’. It can be low-density or high-density and several variations thereof. Its properties can be modified further by cross-linking or co-polymerization. All forms are non-toxic as well as chemically resilient, contributing to polyethylene’s popularity as a multi-use plastic. However, poly-ethylene’s chemical resilience also makes it a long-lived and decomposition-resistant pollutant when disposed of improperly. Being a hydro-carbon, poly-ethylene is colourless to opaque (without impurities or colorants) and combustible.
Polyethylene glycol (PEG) – It is a synthetic polymer made by linking ethylene oxide molecules together. It is known for its water solubility and is used in several applications, including industrial processes. Polyethylene glycol can be a liquid or a waxy solid, depending on its molecular weight.
Polyethylene pellet – It is a small, spherical or granular form of polyethylene, used as the raw material for manufacturing several plastic products. These small plastic pieces, also called particles or nurdles, are the basic building blocks for several items. They are produced through a polymerization process and are designed for efficient use in moulding and extrusion machinery.
Polyethylene terephthalate (PET) – It is the most common thermo-plastic polymer resin of the polyester family and is used in fibres for clothing, containers for liquids and foods, and thermoforming for manufacturing, and in combination with glass fibre for engineering resins. In the context of textile applications, poly-ethylene terephthalate is referred to by its common name, polyester, whereas the acronym PET is normally used in relation to packaging. Poly-ethylene terephthalate consists of repeating (C10H8O4) units. Poly-ethylene terephthalate is normally recycled.
Poly-ethyl-oxazoline – It is also written a poly(2-ethyl-2-oxazoline) and frequently abbreviated as PEtOx or PEOx. It is a synthetic polymer known for its biocompatibility and water solubility, particularly at temperatures below its cloud point (around 60 deg C). It is a type of poly(2-oxazoline), a class of polymers synthesized through cationic ring-opening polymerization of 2-oxazoline monomers. PEtOx is considered a ‘pseudo polypeptide’ because of its structural similarity to polypeptides.
Polyformaldehyde – It is also known as polyoxymethylene (POM) or acetal. It is a formaldehyde-based thermoplastic engineering plastic prized for its high stiffness, low friction, excellent dimensional stability, and abrasion resistance, making it a common replacement for metal parts in applications like gears, bearings, and precision components. It is a high-density, crystalline polymer which can be formed into homopolymers (acetal homopolymer) or copolymers, with different structures affecting thermal stability and resistance to acids and bases.
Poly-generation systems – These are energy generation or conversion systems with multiple input energy sources and multiple output energy produces.
Polyglycerol – It is a synthetic, branched polymer of repeating glycerol units linked by ether bonds. It is known for being biocompatible, viscous, and water-soluble, with applications in biodegradable plastics and lubricants.
Polygon – It is a two-dimensional closed shape formed by connecting three or more straight line segments, end-to-end, where no two segments intersect except at their endpoints. Polygons are defined by their sides (the line segments) and vertices (the points where the sides meet).
Polygonal chain – It is a connected series of line segments. More formally, a polygonal chain P is a curve specified by a sequence of points (A1,A2,…,An) called its vertices. The curve itself consists of the line segments connecting the consecutive vertices. A simple polygonal chain is one in which only consecutive segments intersect and only at their endpoints. A closed polygonal chain is one in which the first vertex coincides with the last one, or, alternatively, the first and the last vertices are also connected by a line segment. A simple closed polygonal chain in the plane is the boundary of a simple polygon. Frequently, the term polygon is used in the meaning of closed polygonal chain, but in some cases, it is important to draw a distinction between a polygonal area and a polygonal chain. A space closed polygonal chain is also known as a skew polygon. A polygonal chain is called monotone, if there is a straight line ‘L’ such that every line perpendicular to L intersects the chain at most once. Every nontrivial monotone polygonal chain is open. In comparison, a monotone polygon is a polygon (a closed chain) which can be partitioned into exactly two monotone chains. The graphs of piecewise linear functions form monotone chains with respect to a horizontal line.
Polygonal curve – It is a curve made up of a sequence of connected, straight line segments. It is a simple closed curve, meaning it does not cross itself and forms a complete loop. A polygon has at least three sides and is classified by the number of its straight sides.
Polyhedral inclusions – These are inclusions whose morphology of dendrite shaped inclusions has been improved by addition (after deep deoxidation by aluminum) of small quantities of rare earth (cerium, lanthanum) or alkaline earth (calcium, magnesium) elements. Since their shape nearing the globular shape, polyhedral inclusions cause less effect on the steel properties than dendrite shape inclusions.
Polyhedron – It is defined as a three-dimensional solid bounded by a finite number of polygons called faces, with points where three or more faces meet referred to as vertices, and line segments where exactly two faces meet called edges.
Polyimide (PI) – It is a polymer produced by reacting an aromatic dianhydride with an aromatic diamine. It is a highly heat-resistant resin. It is similar to a polyamide, differing only in the number of hydrogen molecules contained in the groupings. It is suitable for use as a binder or adhesive. It can be either thermoplastic or thermoset. Polyimide resins are available with a maximum hot / wet in-service temperature of 232 deg C and above (up to 370 deg C for single use short periods). These resins cure by a condensation reaction which releases volatiles during cure at 315 deg C and higher.
Polyionic polymers – These are polymers with an ionic functional group. The ionic charges prevent the formation of tightly coiled polymer chains. This allows them to contribute more to viscosity in their stretched state, since the stretched-out polymer takes up more space. This is also the reason gel hardens.
Polyisobutylene (PIB) – It is a synthetic polymer and a type of synthetic rubber, formed by the polymerization of isobutylene. It is a versatile material known for its excellent elasticity, chemical resistance, and gas impermeability. Depending on its molecular weight, it can range from a viscous liquid to a sticky, gummy solid or a rubbery material. Polyisobutylene is used in a wide array of applications, including lubricants, adhesives, sealants for insulating glass, and in the production of synthetic rubber, sometimes called butyl rubber.
Polyisoprene rubber – It is a natural or synthetic elastomer, a polymer formed from isoprene units, which functions similarly to natural rubber and shares its elastic properties. Natural polyisoprene is the primary component of natural rubber, while synthetic polyisoprene is engineered to mimic its properties, offering high strength, resilience, and resistance to tearing and abrasion. It is a crucial material in the production of tires, various medical devices, and consumer goods due to its elasticity and strength.
Polymer – It is a high-molecular-weight organic compound, natural or synthetic, with a structure which can be represented by a repeated small unit, the mer. Examples include polyethylene, rubber, and cellulose. Synthetic polymers are formed by addition or condensation polymerization of monomers. Some polymers are elastomers, some are plastics, and some are fibres. When two or more dissimilar monomers are involved, the product is called a copolymer. The chain lengths of commercial thermo-plastics vary from around 1,000 to higher than 100,000 repeating units. Thermo-setting polymers approach infinity after curing, their resin precursors, frequently called prepolymers, can be relatively short (6 to 100 repeating units) before curing. The lengths of polymer chains, normally measured by molecular weight, have very considerable effects on the performance properties of plastics and profound effects on processibility. Polymers, both natural and synthetic, are created through polymerization of several small molecules, known as monomers. Their consequently large molecular mass, relative to small molecule compounds, produces unique physical properties including toughness, high elasticity, viscoelasticity, and a tendency to form amorphous, and semi-crystalline structures rather than crystals.
Polymer binder – It is a polymeric material which acts as a glue to hold particles or components together, forming a cohesive structure in a variety of applications, including batteries, ceramic parts, electrode materials. These polymers, such as vinyl and acrylics, work by forming inter-particle bonds through mechanical interlocking, chemical bonding, or other forces, ensuring structural integrity and improving the performance and durability of the final product.
Polymer blend -It is a mixture of different types of polymer chains. In miscible blends the polymers mix on a molecular level to produce a single phase, as in the blend of poly-phenylene oxide and poly-styrene. In immiscible blends the polymers cannot mix on a molecular level and separate into two phases, as in blends of acrylonitrile butadiene styrene (ABS) and polystyrene.
Polymer casting – To form a ‘plastic’ object by pouring a fluid monomer-polymer solution into an open mould where it finishes polymerizing. Forming plastic film and sheet by pouring the liquid resin onto a moving belt or by precipitation in a chemical bath.
Polymer chain – It is a long molecule formed by monomers (smaller units) which are linked together by chemical bonds in a repeating sequence, similar to a chain of connected paperclips. These long, repeating chains, which can be linear, branched, or networked, give polymers their large molecular size and determine several of their properties, such as their flexibility, strength, and behaviour in different environments.
Polymer composite – It is a material formed from two or more constituent materials with different chemical and physical properties, where at least one is a polymer, which combine to create a new material with superior properties not achievable by the individual components alone. These composites typically consist of a polymer matrix which binds and protects a dispersed reinforcement material, such as fibres or particles, creating a strong, lightweight material with tailored characteristics for specific applications.
Polymer conveyor chain – It is a conveyor chain made from polymer materials, delivering advantages such as corrosion resistance and reduced noise. Regular evaluations are essential to monitor wear, tension, and overall chain integrity.
Polymer derived ceramics – These are the ceramics which are produced from polymers by pyrolysis.
Polymer electrolyte membrane (PEM) – It is also known as a proton exchange membrane. It is a solid-state ionic conductor, typically a polymeric material, which selectively facilitates the transport of specific ions (normally protons) while acting as an electronic insulator and a barrier to reactants like gases.
Polymer electrolyte membrane (PEM) fuel cell – It is an electro-chemical device which converts chemical energy from fuel, typically hydrogen, directly into electrical energy, producing water as the only by-product. It operates at low temperatures using a solid polymer membrane as the electrolyte, which conducts protons from the anode, where fuel is oxidized, to the cathode, where oxygen is reduced. Polymer electrolyte membrane fuel cell are known for their high-power density, compact size, and quick start-up, making them suitable for transportation and portable power applications.
Polymer electrolyte membrane (PEM) process – It refers to the operation of devices, most notably polymer electrolyte membrane fuel cells, where a solid, proton-conducting polymer membrane selectively allows protons (hydrogen ions) to pass from an anode to a cathode while preventing the passage of other gases and electrons. This key component facilitates the electro-chemical reaction between hydrogen and oxygen to produce electricity, heat, and water by conducting protons to react with oxygen at the cathode, while electrons are routed through an external circuit, generating usable current.
Polymer exchange membrane (PEM) – It is also known as a proton exchange membrane. It is a thin, solid polymer-based material which acts as an electrolyte in fuel cells and electrolyzers. Its primary function is to selectively conduct positively charged ions protons) between the anode and cathode while blocking the direct passage of electrons and other reactant gases like hydrogen and oxygen. This selective ion transport is crucial for enabling the electrochemical reactions which produce electricity from hydrogen and oxygen, with the protons moving through the membrane and reacting with oxygen and electrons to form water.
Polymeric coating – It is a protective or functional layer of polymer material applied to a substrate’s surface to improve its properties. These coatings can provide protection against corrosion, wear, and environmental hazards, or be used for decorative, functional, and surface-modification purposes. Common applications include protecting metal structures, and several textiles and paper products.
Polymeric membrane process for air separation – The process is based on the membrane separation technology. It makes use of the different rates at which air gases diffuse through a polymer membrane. Membrane processes using polymeric materials are based on the difference in rates of diffusion of oxygen and nitrogen through a membrane which separates high-pressure and low-pressure process streams. Membrane separation technology uses tube bundles made of special polymers, frequently configured in a manner similar to a shell and tube heat exchanger. The air separation principle is that different gases have different permeation rates through the polymer film.
Polymeric process – It means the use, injection or application of a polymeric chemical product.
Polymer infiltration and pyrolysis (PIP) – It is the method of fabrication of ceramic matrix composites comprising an infiltration of a low viscosity polymer into the reinforcing ceramic structure (e.g., fabric) followed by pyrolysis i.e., heating the polymer precursor in the absence of oxygen when it decomposes and converts into a ceramic. The ceramics produced from polymers by pyrolysis are called polymer derived ceramics.
Polymer injection technology – It is an exciting new patented process, which partially substitutes the use of coke with polymers, including rubber (used tires), as an alternate carbon injectant to produce foaming slag in electric arc furnace steelmaking. The benefits include (i) reduced specific electrical energy consumption of around 3 %, (ii) reduced carbon injectant of around 12 %, (iii) increased furnace productivity (tons per minute) of 4 %, (iv) slag FeO (ferrous oxide) levels are maintained within the needed range, and (v) reduced emission levels for nitrogen oxides (NOx), carbon mono-oxide, and sulphur di-oxide.
Polymerization – It is the chemical bonding of two or more individual monomer molecules to form a polymer chain or network, or any reaction which produces such a bonding. It is a chemical reaction in which the molecules of a monomer are linked together to form large molecules whose molecular weight is a multiple of that of the original substance. When two or more monomers are involved, the process is called copolymerization.
Polymer matrix – It is the resin portion of a reinforced or filled plastic.
Polymer matrix composite – It is a composite material composed of a variety of short or continuous fibres bound together by a matrix of organic polymers. Polymer matrix composites are designed to transfer loads between fibres of a matrix.
Polymer processing – It involves creating structures using polymers by changing their viscosity and rheological properties and shaping them.
Polymer quenchants – These are water-based solutions used in heat treatment processes to cool heated metal. They offer a cooling rate which is between that of water and oil, hence providing flexibility and safety advantages. They are typically polyalkylene glycol (PAG) or polyvinyl pyrrolidone (PVP) based.
Polymer quenching – It is a heat treatment process where heated metal is rapidly cooled in a bath containing a water-soluble polymer solution. This method offers a controlled cooling rate, typically falling between that of water and oil quenching, making it suitable for materials that may be sensitive to the faster cooling of water or the slower cooling of oil. Polymer quenchants, frequently polyalkylene glycol (PAG) or polyvinyl pyrrolidone (PVP), provide a more flexible approach to heat treatment than traditional methods.
Polymers – They consists of a high molecular weight organic compound, natural or synthetic, with a structure which can be represented by a repeated small unit, the mer. Synthetic polymers are formed by addition or condensation polymerization of monomers. When two or more dissimilar monomers are involved, the product is called a copolymer. The lengths of polymer chains, normally measured by molecular weight, have very significant effects on the performance properties of plastics and profound effects on processability.
Polymethyl methacrylate (PMMA) – It is a synthetic polymer derived from methyl methacrylate. It is a transparent thermoplastic, used as an engineering plastic. It is also known as acrylic, and acrylic glass. It is frequently used in sheet form as a lightweight or shatter-resistant alternative to glass. It can also be used as a casting resin, in inks and coatings, and for several other purposes. It is frequently technically classified as a type of glass, since it is a non-crystalline vitreous substance.
Polymorph – In crystallography, it is one crystal form of a polymorphic material.
Polymorphism – · In crystallography, it is the property of a chemical substance whereby it crystallizes into two or more forms having different crystallographic structures, such as diamond against graphite or face centred cubic iron against body centred cubic iron. It is a general term for the ability of a solid to exist in more than one form. In metals, alloys, and similar substances, this normally means the ability to exist in two or more crystal structures, or in an amorphous state and at least one crystal structure.
Polynomial basis function – It is a mathematical building block, typically a variable raised to an increasing power (e.g., 1, x, x square, x cube, ——), used to construct more complex polynomial functions which can model non-linear relationships between variables in datasets, particularly in regression models. By combining these simple polynomial terms with different coefficients, a wide range of complex curves can be approximated, which is the core idea behind polynomial regression.
Polyolefin – It is a type of polymer, or long-chain molecule, produced by joining together smaller olefin (or alkene) units, such as ethylene and propylene, through a process called polymerization. These are thermoplastic polymers, meaning they can be melted and reshaped, and they are widely used to create common products like polyethylene and polypropylene.
Polyolefin rubber – It refers to a class of synthetic elastomers produced from polyolefin monomers, such as ethylene-propylene rubber (EPM) and ethylene-propylene-diene monomer (EPDM), known for their outstanding resistance to ozone, weathering, and chemicals. These flexible, durable materials are versatile, used in everything from automotive parts and consumer goods to construction and packaging.
Poly-oxy-methylene – It is an engineering thermo-plastic used in precision parts needing high stiffness, low friction, and excellent dimensional stability.
Poly-phase coil – It is a coil intended for connection to a polyphase power supply.
Poly-phase system – It is an alternating current power transmission system using three or more wires, each of which carries a current that is displaced in time with respect to the others. It is a means of distributing alternating-current electrical power which utilizes more than one alternating current phase, which refers to the phase offset value (in degrees) between alternate current in multiple conducting wires. Phases can also refer to the corresponding terminals and conductors, as in colour codes. Poly-phase systems have two or more energized electrical conductors carrying alternating currents with a defined phase between the voltage waves in each conductor. Early systems used 4 wire two-phase with a 90-degree phase angle, but modern systems almost universally use three-phase voltage, with a phase angle of 120-degree (or 2 pi/3 radians). Poly-phase systems are particularly useful for transmitting power to electric motors which rely on alternating current to rotate. Three-phase power is used for industrial applications and for power transmission. Compared to a single-phase, two-wire system, a three-phase three-wire system transmits three times as much power for the same conductor size and voltage, using only 1.5 times as several conductors, making it twice as efficient in conductor utilization.
Polyphenylene oxide (PPO) – It is also known as polyphenylene ether (PPE). It is a high-temperature thermoplastic polymer characterized by its high heat resistance, dimensional stability, and low moisture absorption. It is produced through oxidative coupling polymerization and is rarely used in its pure form, but rather as blends with other polymers like polystyrene (PS) or polyamide to improve processing. These blends are valued for their excellent electrical, mechanical, and thermal properties, making them suitable for automotive components, electrical devices, and other applications needing resistance to heat and moisture.
Polyphenylene ether (PPE) – It is a high-performance thermoplastic known for its excellent heat resistance, dimensional stability, and mechanical properties. It is frequently blended with polystyrene (PS) or nylon to improve its processability and toughness. Polyphenylene ether shows low moisture absorption, good chemical resistance, and strong dielectric properties, making it suitable for several applications, particularly in electronics, automotive, and industrial sectors.
Polyphenylene sulphide (PPS) – It is an organic polymer consisting of aromatic rings linked by sulphides. Synthetic fibre and textiles derived from this polymer resist chemical and thermal attack.
Polyphenyl ether (PPE) – It is also known as polyphenylene oxide (PPO). It is a high-performance thermo-plastic known for its exceptional thermal and electrical properties, excellent chemical resistance, and low water absorption. It is an amorphous polymer with good dimensional stability, making it suitable for several demanding applications, particularly in the electrical and electronics industries.
Polypropylene (PP) – It is a common thermoplastic polymer with excellent properties, including high gas and water permeability resistance, mechanical properties, flame resistance, high heat distortion temperature and others. Polypropylene is widely used in polymer materials in the plastic manufacturing industry to produce various end products, especially plastic packaging.
Polypropylene fibre-reinforced concrete – It is concrete which has small, synthetic polypropylene fibres added to its mix to improve its mechanical properties and durability. These fibres improve the concrete’s resistance to cracking, especially from shrinkage, and also boost its impact and tensile strength, making it suitable for high-performance construction applications. The fibres form a three-dimensional network within the concrete, increasing its toughness and overall structural integrity.
Polysilicon – It is a highly purified form of silicon made of multiple small silicon crystals, serving as a fundamental raw material for the production of solar cells and electronic devices. It is manufactured through a chemical purification process, such as the Siemens process, where raw materials are refined into high-purity polysilicon. This material is then melted to form ingots, which are sliced into wafers and subsequently processed into photovoltaic (PV) cells or integrated into different electronic components.
Polysilicon film – It is a thin, deposited layer of polycrystalline silicon, which consists of several small silicon crystals. These films are produced through processes like chemical vapour deposition (CVD) and are used extensively in semiconductor devices and commercial photovoltaic cells. The material’s properties are similar to single-crystal silicon but are influenced by the grain boundaries between the individual crystals.
Polysiloxane – It is also known as a silicone. It is a synthetic polymer with a flexible backbone of alternating silicon and oxygen atoms, to which organic groups (like methyl groups) are attached. This unique structure gives polysiloxanes exceptional flexibility, high thermal and oxidative stability, chemical resistance, and low surface tension. These versatile materials are used in diverse applications, including lubricants, sealants, and heat-resistant materials.
Poly-sodium acrylate – It is also known as sodium polyacrylate. It is a super-absorbent polymer (SAP) with the chemical formula [−CH2−CH(CO2Na)−]n. It is a sodium salt of polyacrylic acid and is characterized by its ability to absorb and retain large quantities of water relative to its own mass. This property makes it widely used in several applications.
Polystyrene (PS) – It is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It is a poor barrier to air and water vapour and has a relatively low melting point. Polystyrene is one of the most widely used plastics, with the scale of its production being several million tons per year. Polystyrene is naturally transparent to visible light, but can be coloured with colourants. Uses include protective packaging, containers, lids, bottles, trays, tumblers, disposable cutlery, in the making of models, and as an alternative material for phonograph records. As a thermo-plastic polymer, polystyrene is in a solid (glassy) state at room temperature but flows if heated above around 100 deg C, its glass transition temperature. It becomes rigid again when cooled. This temperature behaviour is exploited for extrusion and also for moulding and vacuum forming, since it can be cast into moulds with fine detail. The temperatures behaviour can be controlled by photo-crosslinking. Polystyrene is regarded as not bio-degradable. It is accumulating as a form of litter in the outside environment.
Polystyrene-di-vinyl benzene resin – It is a porous polymer resin which is used in different applications, including chromatography, catalysis, and adsorption. It is used in majority of ion exchange applications. The resin which has ionic sites consisting of mobile charge of ‘SO-H’ radicals and mobile sodium cations (Na+), removes the cations present in water (hence called cation exchange resins). The resin which has tertiary or quaternary ammonium group as mobile cationic radicals and mobile chloride anions (Cl-), removes the anions including silicic and carbonic acids present in water (hence called anion exchange resins).
Polysulphide – It is a synthetic polymer containing sulphur and carbon linkages, produced from organic dihalides and sodium polysulphide. Material is elastomeric in nature, resistant to light, oil, and solvents, and impermeable to gases.
Polysulphone – It is a high-temperature-resistant thermoplastic polymer with the sulfone linkage, with a ‘Tg’ of 190 deg C.
Polytechnic – It is an institution or a course of study which provides practical, hands-on training for technical professions, particularly in engineering and applied sciences, leading to a diploma rather than a full bachelor’s degree. The term ‘polytechnic’ comes from the Greek words poly (many) and tekhne (skill or art), signifying instruction in several technical skills or applied sciences. These programs focus on developing industry-specific skills and knowledge, preparing students for entry-level roles like junior engineer in several technical fields such as mechanical, civil, or electrical engineering.
Poly-tetra-fluoro-ethylene (PTFE) – It is a synthetic fluoropolymer of tetra-fluoro-ethylene, and has several applications since it is chemically inert. Poly-tetra-fluoro-ethylene is a fluorocarbon solid, as it is a high-molecular-weight polymer consisting wholly of carbon and fluorine. It is hydrophobic i.e., neither water nor water-containing substances wet it, since fluoro-carbons show only small London dispersion forces because of the low electric polarizability of fluorine. It has one of the lowest coefficients of friction of any solid. Poly-tetra-fluoro-ethylene is non-reactive, partly because of the strength of carbon–fluorine bonds, so it is frequently used in containers and pipework for reactive and corrosive chemicals. Where used as a lubricant, poly-tetra-fluoro-ethylene reduces friction, wear, and energy consumption of machinery.
Poly-tier support – It consists of adjustable support structures which are designed to accommodate the load and weight of multi-tiered conveyor systems.
Polytropic process – It is a thermodynamic process in which the pressure and volume of a gas or fluid change in a way that is described by the polytropic equation. Mathematically, the polytropic equation is defined as (PV) to the power ‘n’, where ‘P’ is pressure, ‘V’ is volume, ‘n’ is the polytropic index, and ‘C’ is a constant. The polytropic index, ‘n’, is a dimensionless number which describes the relationship between pressure and volume for a particular system. When n = 1, the process is isothermal, when n = 0, it becomes an isochoric process, when n = infinity, it becomes isobaric, and when n = sigma, it becomes adiabatic. where sigma = Cp/Cv is the heat capacity ratio. Graphically, this process can be represented as polytropic process PV diagram.
Polyunsaturated fatty acid methyl ester (PUFAME) – It is a fatty acid methyl ester (FAME) with multiple carbon-carbon double bonds in its structure, most notably in the context of biodiesel fuels. While fatty acid methyl esters are used to produce biodiesel from sources like vegetable oils and animal fats, the high degree of unsaturation in polyunsaturated fatty acid methyl esters makes them more susceptible to oxidative degradation, which can negatively impact the oxidation stability and longevity of the fuel. This makes the control and reduction of polyunsaturated fatty acid methyl ester content a key engineering consideration for improving biodiesel quality and performance.
Polyurethane – It is a polymer composed of a chain of organic units joined by carbamate (urethane) links. It is a thermosetting resin prepared by the reaction of diisocyanates with polyols, polyamides, alkyd polymers, and polyether polymers.
Polyurethane (PU) film – It is a thin, flexible layer of a versatile polymer synthesized from a polyol and a diisocyanate, known for its exceptional durability, flexibility, and resistance to abrasion, chemicals, and weathering. It serves as a critical protective barrier, adhesive, or structural component in diverse applications, offering a customizable balance of strength and elasticity for specific engineering challenges.
Polyvinyl alcohol (PVA) – It is a water-soluble synthetic polymer. It has the idealized formula [CH2CH(OH)]n. It is used as a thickener and emulsion stabilizer in polyvinyl acetate adhesive formulations, in a variety of coatings, and 3D printing. It is colourless (white) and odourless. It is normally supplied as beads or as solutions in water.
Polyvinyl chloride (PVC) – It is a synthetic polymer of plastic. It comes in rigid (sometimes abbreviated as RPVC) and flexible forms. Rigid poly-vinyl chloride is used in construction for pipes, doors and windows. It is also used in making plastic bottles, packaging, and bank or membership cards. Adding plasticizers makes poly-vinyl chloride softer and more flexible. It is used in plumbing, electrical cable insulation, flooring, inflatable products, and in rubber substitutes. With cotton or linen, it is used in the production of canvas. Poly-vinyl chloride is a white, brittle solid. It is soluble in ketones, chlorinated solvents, di-methyl-formamide, tetra-hydro-furan, and di-methyl-acetamide.
Polyvinyl fluoride (PVF) – Its formula is (CH2CHF)n. It is a thermoplastic fluoro-polymer with a repeating vinyl fluoride unit. It is structurally very similar to polyvinyl chloride. It is a polymer material which is mainly used in the flammability-lowering coatings of airplane interiors and photovoltaic module back-sheets. It is also used in metal sheeting.
Polyvinylidene chloride (PVDC) – It is a synthetic, inert, semi-crystalline polymer known for its exceptional barrier properties against gases and water vapour, frequently produced through the emulsion polymerization of vinylidene chloride. Its applications leverage its high impermeability, such as in high-performance packaging films, filters, and coatings for other plastics to extend shelf life and improve barrier performance.
Polyvinylidene di-fluoride – It is also called poly-vinylidene fluoride. It is a highly non-reactive thermoplastic fluoropolymer produced by the polymerization of vinylidene difluoride. Its chemical formula is (C2H2F2)n. Poly-vinylidene di-fluoride is a specialty plastic which is used in applications needing the highest purity, as well as resistance to solvents, acids and hydro-carbons. Poly-vinylidene di-fluoride has low density 1.78 grams per cubic centimeter in comparison to other fluoro-polymers, like poly-tetra-fluoro-ethylene.
Polyvinylidene fluoride (PVDF) – It is a highly non-reactive and durable thermoplastic fluoropolymer known for its excellent chemical resistance, thermal stability, and piezoelectric properties. It is a versatile material used in a wide range of applications, including electrical insulation, and chemical processing devices.
Polyvinyl-pyrrolidone (PVP) – It is normally called polyvidone or povidone, is a water-soluble polymer compound made from the monomer N-vinylpyrrolidone. Polyvinyl-pyrrolidone is available in a range of molecular weights and related viscosities, and can be selected as per the desired application properties.
Pontryagin’s minimum principle – It is a mathematical principle which is used in the theory of optimal control.
Pontoon – It is a buoyant, hollow, or airtight structure, typically made of steel, aluminum, or plastic, used to provide flotation and support for various applications over water. Pontoons are widely used as individual components in floating platforms for dredging and heavy lifting, for seaplane floats, or linked together to form floating bridges, docks, and other temporary structures in marine and civil engineering.
Pooled point estimate – it is an approximation of a point, normally a mean or variance, which combines information from two or more independent samples believed to have the same characteristics. It is used to assess the effects of treatment samples versus comparative samples.
Pool reactor – It is a reactor in which fuel elements are submerged in an open water pool. The water serves as a moderator, reflector and coolant. It is popularly called a ‘swimming pool reactor’, it is used for research and training, not for electricity generation.
Pop-off – It is the loss of small portions of a porcelain enamel coating. The normal cause is outgassing of hydrogen or other gases from the substrate during firing, but pop-off can also occur because of oxide particles or other debris on the surface of the substrate. Normally, the pits are minute and cone shaped, but when pop-off is the result of severe fish scale the pits can be much larger and irregular.
Pop-out roller – It is a roller is which typically positioned at the ends of a belt conveyor, aiding in transfer, and set in a broad groove to eject if an object intervenes between it and the belt.
Poppet valve – It is a valve which uses a plug or disk-shaped element to control the flow of fluids or gases, operating by lifting off a seat and then returning to seal the port. It is also known as a mushroom valve because of its shape, consisting of a head and a stem, and is actuated by a spring that holds it on its seat, with an external force like a cam lifting it to open. Poppet valves are common in internal combustion engines to regulate the intake and exhaust of gases and are also used in several industrial applications for their high flow, fast response, and precise control capabilities.
Pop, solvent – It consists of blister and / or void in the coating resulting from trapped solvents released during curing process.
Population – It is a group of individuals of the same species living and interbreeding within a given area. Members of a population frequently rely on the same resources, are subject to similar environmental constraints, and depend on the availability of other members to persist over time. In statistics, population is the complete set of all possible elements or objects. Each of the elements is called a piece of data. Population is a collection of units or objects of which some property is defined for every unit or object. Population can consist of finite or infinite number of units. Population is also called universe by some peoples. The number of employees in the organization, number of rolling mills in a plant, length of rail track in the plant, and number of feeders in a sinter plant are a few examples of finite populations. All real numbers, and inclusions in liquid steel are examples of infinite populations. Normally, the population has a large number of animates and inanimates. Moreover, the units or subjects constituting the population can vary from study to study in the same area of activity depending upon the aims and objective of the study. In brief, one is to keep in mind that statistical population of data is not the human population which is normally considered for population in literary sense. It is normally a group or collection of items specified by certain characteristics or defined under certain restrictions. Population is the total collection of cases people wish to generalize the results of their study to. In statistical usage the term population is applied to any finite or infinite collection of individuals. The term population is also used for the infinite population of all possible results of a sequence of statistical trials, for example, tossing a coin. It is important to distinguish between the population, for which statistical parameters are fixed and unknown at any given instant in time, and the sample of the population, from which estimates of the population parameters are computed. Population statistics are normally unknown since the analyst can rarely afford to measure all members of a population, and so a random sample is drawn. Much of statistics is concerned with estimating numerical properties (parameters) of an entire population from a random sample of units from the population. Greek letters are normally used for population parameters. This is to distinguish them from sample statistics.
Population density – It is the size of a population in relation to the quantity of space which it occupies. Density is normally expressed as the number of individuals per unit area or volume. Like all population properties, density is a dynamic characteristic which changes over time since individuals are added to or removed from the population.
Population inversion – It is the non-equilibrium state of a system (like atoms or molecules) where more particles are in a higher energy state than in a lower energy state, a condition contrary to thermal equilibrium where the opposite is true. This state is an important prerequisite for light amplification through stimulated emission, which forms the basis of laser operation and semi-devices. Energy is supplied to the system, a process called pumping, to achieve population inversion.
Porcelain – It is a glazed or unglazed vitreous ceramic whiteware used for technical purposes. This term designates such products as electrical, chemical, mechanical, structural, and thermal wares when they are vitreous. This term is frequently used as a synonym for china.
Porcelain enamel – It is a substantially vitreous or glassy, inorganic coating (borosilicate glass) bonded to metal by fusion at a temperature above 425 deg C. Porcelain enamels are applied primarily to components made of sheet iron or steel, cast iron, aluminum, or aluminum-coated steels.
Pore – It is a small opening, void, interstice, or channel within a consolidated solid mass or agglomerate, normally larger than atomic or molecular dimensions. It is a minute cavity in a powder metallurgy compact, sometimes added intentionally. It is a minute perforation in an electroplated coating. It is an inherent or induced cavity (void) within a particle or within an object.
Pore area – It is the effective surface porosity of a sintered compact to determine the permeability to a test fluid.
Pore channels – These are the connections between pores in a sintered body.
Pore formation – It consists of the natural formation of pores during compaction and / or sintering.
Pore forming material – It is a substance included in a powder mixture which volatilizes during sintering, and hence produces a desired kind of porosity in a finished compact.
Pore size – It is the width of a pore in a compacted and / or sintered powder or within a particle.
Pore size distribution – It indicates the volume fractions of different pore size categories, which are determined metallographically.
Pore size range – It consists of the limits between which a variation in pore size is allowed.
Pore space – It refers to the void volume within a porous material (like soil, rock, or concrete) which is not occupied by solid material, and which can contain fluids like water or gas. This interconnected network of empty spaces, characterized by its porosity (the fraction of the total volume that is void) and pore size distribution, is important since it determines how fluids and gases move through the material, influencing properties like permeability, strength, and reactivity.
Pore structure – It consists of pattern of pores in a solid body indicating such characteristics as pore shape, pore size, and pore size distribution.
Pore wall – It is the interface between the pore and the solid.
Porosimeter – It is a test apparatus to measure the interconnected porosity in a sintered compact by means of determining its permeability through the use of a test fluid such as mercury, which wither partially or completely fills the open pore.
Porosity – Porosity is small cavities or bores which are found on the surface of the weld or slightly below surface. Porosity occurs when some constituents of the liquid metal vapourize causing small gas pockets which get entrapped in the liquid metal as it solidifies. These small cavities or bores can have a variety of shapes but mostly they have a spherical shape. The distribution of cavities and bores in weld metal can be linear (linear porosity) or theses can be clustered together (cluster porosity). In general, porosity can result from the presence of dirt, rust or moisture on the surface of base or filler metal. Also, it can result from high sulphur content in the base metal or excessive arc length. Molten weld metal has a considerable capacity for dissolving gases which come into contact with it such as hydrogen, oxygen and nitrogen. As the molten weld metal cools its ability to retain the gases reduces. With the change from the liquid to the solid state, there is reduced solubility with falling temperature. This causes evolution of gas at a time when the metal is becoming mushy and hence incapable of permitting the gas to escape freely. Entrapment of the gas causes gas pockets and porosity in the final weld. The porosity can be of three types namely (i) fine porosity, (ii) blow holes, and (iii) piping. Fine porosity consists of small bubbles of gas normally of diameter less than 1.5 millimeters. Porosity can be scattered uniformly throughout the weld, isolated in small groups, or concentrated at the root of the weld. Different causes of porosity include excessive moisture content of the electrode covering, incorrect electrode current, defective gas shielding, contamination of joint surface or filler wire, and rapid cooling of the weld metal or the composition of the electrode core wire or parent steel.
Porosity, blow-holes – These are holes in the casting because of gases trapped in the mould, reaction of molten metal with moisture in the moulding sand, or imperfect fusion of chaplets with molten metal.Surface porosity can be because of the overheating of the mould or core faces, but are not to be confused with sand inclusions.
Porosity measurement – It is the assessment of the volume of void spaces within a material, expressed as a fraction or percentage of the material’s total volume. It quantifies the empty space and is crucial for understanding material properties and predicting performance, as it influences characteristics such as strength, permeability, and storage capacity.
Porous alumina – It is an engineered aluminum oxide ceramic (Al2O3) characterized by an intentionally controlled network of pores which improve its properties, making it useful for filtration, high-temperature insulation, and catalyst supports. Unlike naturally occurring dense alumina, porous alumina’s tailored pore structure provides advantages like high surface area, adjustable permeability, thermal insulation, and chemical inertness, enabling specific high-performance applications.
Porous asphalt (PA) – It is a permeable asphalt concrete surface with a high air-void content (typically 15 % to 25 %) which allows water to drain through it, managing stormwater, reducing runoff, and minimizing noise. Its open, stone-on-stone aggregate structure creates interconnected voids, enabling water infiltration into an underlying stone base, which can then recharge groundwater. Porous asphalt is used in permeable pavements for parking lots and other surfaces to improve water quality, recharge aquifers, and create cooler, quieter environments.
Porous baffles – These are permeable barriers in fluid flow systems which allow fluid to pass through their structure, unlike solid baffles. They are used to alter flow patterns, control fluid turbulence, and dampen sloshing in tanks by influencing the mass flow rate and enabling fluid recirculation through their pores. Examples include perforated plates, wire screens, and porous membranes used in heat exchangers, sediment basins, and sloshing tanks.
Porous bearing – It is a sintered product whose accessible pore volume is filled with a liquid lubricant which automatically produces a lubricating film on the bearing surface during running of the shaft. This is because of a pumping action of the shaft and frictional heat which lowers the viscosity of the oil. After completion of the running cycle, the oil is reabsorbed into the pore system of the bearing by capillary attraction.
Porous bed – It is a material containing interconnected voids or pores which allows fluids (liquids or gases) to flow through it. These beds are characterized by a specific volume of empty space, known as porosity, and are used in applications like filtration, adsorption, and energy storage where fluid interaction with the solid material is essential.
Porous coating – It is a thin surface layer on a material which is intentionally designed with a structure containing numerous voids or cavities, creating a porous matrix that alters the surface’s properties. These coatings are used to improve performance in applications like boiling heat transfer by increasing nucleation sites, or create superhydrophobic surfaces. The porosity, particle size, and thickness of the coating are carefully optimized to achieve desired mechanical, chemical, and thermal characteristics.
Porous electrode – It is an electrically conductive material featuring a three-dimensional network of interconnected pores which are permeable to the electrolyte. This complex, high-surface-area microstructure allows for improved electrochemical reactions and transport processes within devices like batteries and fuel cells. The structure of a porous electrode impacts considerably its performance by controlling the distribution of ions, the kinetics of reactions, and overall mass transfer.
Porous inorganic membrane – It is a thin, selectively permeable barrier made from inorganic materials such as ceramics, metals, or zeolites, designed to separate components from a fluid stream. These membranes feature a support layer, which provides mechanical strength, and a porous separation layer with a controlled network of pores of specific sizes (macropores, mesopores, or micropores) to allow specific substances to pass through while blocking others. The pore structure and resulting transport properties determine the membrane’s performance in applications like gas separation, water purification, and membrane reactors, where their high thermal and chemical stability is a substantial advantage over polymeric membranes.
Porous insert – It is a component with a solid matrix containing interconnected voids or pores which is inserted into a larger system to improve heat transfer, mass transport, or fluid flow. These inserts leverage the large surface area and interconnected pore structure to improve efficiency in applications like heat exchangers, fuel cells, and aerodynamic systems by increasing thermal conductivity and enabling fluid passage.
Porous matrix – It is a solid material framework containing interconnected or isolated pores (voids) which can hold and transport fluids, facilitating processes like filtration, catalysis, and energy storage. Its behaviour is defined by key characteristics such as porosity (the volume fraction of voids) and tortuosity (the convoluted path fluid takes through the pores), which influence its mechanical properties and ability to interact with other substances.
Porous metal – It is a metal structure having controlled interconnected porosity.
Porous mould – It is a mould with a connected void structure which allows for the passage of fluids or gases through its material, unlike a non-porous, solid mould. This porosity facilitates processes such as slip casting, where liquid diffuses through the mould’s surface, or pulp moulding, where water is exhausted through the mould’s pores. Porous moulds are used to create shaped products by controlling fluid flow, frequently using materials like sintered metal or specialized polymer ceramics.
Porous plug – It is a device made from porous materials which controls fluid or gas flow by allowing passage through its intricate network of pores while preventing larger contaminants from passing. These specialized plugs serve several functions, such as filtration, aeration, diffusion, and stirring liquid metals to improve uniformity and remove inclusions. They are made from materials like ceramics, metals, and polymers, with their effectiveness depending on pore size, material properties, and the specific application.
Porous refractory burner – In this type of burner, the burner material is ‘porous inert media’ which has been made from a wide variety of ceramics. These ceramics frequently include alumina, zirconia, or silicon carbide. The heat transfer coefficient between the hot exhaust products and the radiant burner material is difficult to predict and measure because of the uncertainty in the surface area of the ceramic structure. These coefficients have traditionally been presented in terms of a volumetric coefficient (kW/ deg C-cum).
Porous rock – It is a rock containing interconnected spaces (pores) which can store or transmit fluids like water, oil, or gas. Its key property is porosity, defined as the ratio of total pore volume to total bulk volume, frequently expressed as a percentage. The interconnectedness of these pores determines the rock’s permeability, which is crucial for fluid flow in applications such as underground storage, aquifers, and hydrocarbon reservoirs.
Porous sample – It is a material characterized by the presence of internal voids or pores within its solid structure, often allowing fluids or gases to permeate through it. The key aspect of a porous sample is its porosity, defined as the ratio of the pore volume to the total volume of the material. These pores can be interconnected (open-cell) or isolated (closed-cell), influencing the material’s density, strength, thermal, and acoustic properties.
Porous silicon – It is a form of silicon characterized by tiny surface pores, which has a high surface-to-volume ratio and is utilized in various applications, including humidity sensors, gas sensors, and electrochemical electrodes. Its unique porosity allows for controlled light emission, with different wavelengths produced depending on the material’s porosity level.
Porous structure – It is a material, typically a metal, which contains a substantial volume of voids or pores (higher than 50 %) distributed throughout its solid phase, with the solid phase normally referred to as dense or parent metal. These structures can show either closed cell forms, like metal foams, or open cell configurations, frequently described as metal sponges, depending on the connectivity of the pores.
Porphyry – It is an igneous rock in which relatively large crystals, called phenocrysts, are set in a fine-grained ground-mass.
Porphyry copper – It is a deposit of disseminated copper minerals in or around a large body of intrusive rock.
Port – It is an opening through which fluid passes. It is a place at which energy can be observed to enter or leave a system. In case of valve, port is the flow control orifice of a control valve. Port is also a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Port is a docking place for ships on the coast of the ocean, a river, or a lake. Ships dock at ports to load and unload their cargo and passengers. Ports play a crucial role in transporting goods and raw materials. They are frequently categorized by their purpose.
Portable – It describes equipment designed for easy transport and relocation, frequently incorporating features like handles or wheels, and capable of operation while moving or once set up in a new location.
Portable conveyors – These are short length flat conveyors which are carried on a wheeled structure. These conveyors are particularly useful for loading and unloading of trucks / transport vehicles. The inclination of the conveyor can normally be adjusted to suit application.
Portable equipments – These are equipments which can be easily transported from job to job or site to site.
Portable instruments – Portable instruments are designed to be moved from one place to another. They are frequently lightweight, compact, and have a portable power source.
Portable optical emission spectrometers – These are important tools for the on-site sorting and identification of metals in the steel scrap. Their analytical precision and accuracy, while not as good as laboratory installed spectrometers, are more than adequate for sorting mixes and most grade verification requirements. A portable spectrometer is capable of separating different types of steel in addition to separating at least 90 % to 95 % of the individual grades which make up each type of steel.
Portable particulate monitor – It is a device which measures the quantity of particulate matter (PM) in the air. It can also measure other pollutants and environmental factors like temperature and humidity.
Portable power supply – It is a compact, mobile energy source designed to deliver electrical power to devices and systems when a traditional grid connection is unavailable, characterized by its high gravimetric and volumetric power density to ensure portability. These systems typically use rechargeable batteries or other stored energy forms to provide reliable power for different applications, from personal electronics to larger equipment, and frequently incorporate power conversion electronics to deliver the appropriate voltage and current.
Portable support – It consists of support mechanisms for portable equipments and conveyors, equipped with castors and wheels to facilitate easy movement.
Portal – It refers very frequently to a portal frame, a structural framework consisting of two vertical columns and a rigid, moment-resisting horizontal beam connecting them. It is used to create large, open spaces by transferring roof loads to the foundations. Less commonly, the term portal can also refer to a web-based gateway to digital information and services. Portal is also the surface entrance to a tunnel or adit.
Portal scraper reclaimer – A portal scraper reclaimer is named after the shape of the reclaimer body connecting the two end carriages. This structure is normally similar in shape to an inverted ‘V’ or a portal frame. Since the portal scraper reclaimer reclaims the material from side of a pile, it is principally similar in operation to the side scraper reclaimer. It overcomes the restriction of limited boom length (up to 30 meters pile widths) of a side scraper reclaimer which is due to its cantilever type arrangement, because of having rail bogie on both sides of the stockpile. Hence, wider pile widths can be handled by a portal scraper reclaimer.
Porter’s 5 forces analysis – Porter’s 5 forces analysis model is a tool which analyzes the competitive intensity within a particular market or industry. This analysis consists of 3 forces from the horizontal competition representing (i) threat of new entrants, (ii) threat of established competitors which is also known as competitive rivalry, and (iii) threat of substitute products / services. The balance 2 forces are from vertical competition represented by (i) bargaining power of the buyers, and (ii) bargaining power of the suppliers. Horizontal competition means that these 3 forces are operating in the same manner within the market and in the vertical competition the 2 forces operate within the supply chain. Moreover, the model displays that four forces are connected to the fifth one which is the competitive rivalry.
Portevin–Le Chatelier (PLC) effect – It describes a serrated stress–strain curve or jerky flow, which some materials show as they undergo plastic deformation, specifically inhomogeneous deformation. This effect has been long associated with dynamic strain aging or the competition between diffusing solutes pinning dislocations and dislocations breaking free of this stoppage. The onset of the Portevin–Le Chatelier effect occurs when the strain rate sensitivity becomes negative and inhomogeneous deformation starts. This effect also can appear on the sample’s surface and in bands of plastic deformation. This process starts at a so-called critical strain, which is the minimum strain needed for the onset of the serrations in the stress–strain curve. The critical strain is both temperature and strain rate dependent. The existence of a critical strain is attributed to better solute diffusivity because of the deformation created vacancies and increased mobile dislocation density. Both of these contribute to the instability in substitutional alloys, while interstitial alloys are only affected by the increase in mobile dislocation densities.
Porthole dies – These are dies which produce extruded hollow products from solid extrusion ingots. These dies incorporate a mandrel as an integral part of the die assembly and leave one or two ‘weld’ seams along the extrusions. Bridge, spider, duo and self-stripping dies are particular types of porthole die.
Portland cement – It is the fundamental ingredient in concrete. It is calcium silicate cement made with a combination of calcium, silicon, aluminum, and iron. Different types of portland cement are produced to meet various physical and chemical requirements. The properties of portland cement during hydration vary according to (i) chemical composition, and (ii) degree of fineness. It is possible to produce different types of cements by changing the percentages of the raw materials. There are eight types of portland cements. These are (i) Type I portland cement which is a normal, general purpose cement suitable for all uses and it is used in general construction projects such as buildings, bridges, floors, pavements, and other precast concrete products, (ii) Type IA portland cement which is similar to Type I with the addition of air-entraining properties, (iii) Type II portland cement which generates less heat at a slower rate and has a moderate resistance to sulphate attack, (iv) Type IIA portland cement which is identical to Type II and produces air-entrained concrete, (v) Type III portland cement which is a high early strength cement and causes concrete to set and gain strength rapidly, and it is chemically and physically similar to Type I, except that its particles have been ground finer, (vi) Type IIIA portland cement which is an air-entraining, high early strength cement, (vii) Type IV portland cement which has a low heat of hydration and develops strength at a slower rate than other cement types, making it ideal for use in dams and other massive concrete structures where there is little chance for heat to escape, and (viii) Type V portland cement which is used only in concrete structures which will be exposed to severe sulphate action, principally where concrete is exposed to soil and groundwater with a high sulphate content.
Portland cement concrete – It is the concrete which is made with normal portland cement. This concrete needs around 2 weeks for achieving a sufficient strength to permit the removal of forms and the application of moderate loads. Such concrete reached its design strengths after around 28 days and continue to gain strength at a slower rate thereafter. On several occasions it is desirable to speed up construction by using high-early-strength cements, which, although more expensive, are capable of obtaining the desired strengths in 3 days to 7 days. These cements are particularly useful for the fabrication of precast members, in which the concrete is placed in forms where it quickly gains desired strengths and is then removed from the forms and the forms are used to produce more members.
Portlandite – It is the natural mineral form of calcium hydroxide, with the chemical formula Ca(Oh)2, which forms under high temperatures or as a common product during the curing of Portland cement. It is a white, crystalline mineral found in several natural environments and is a significant component in the chemical reactions which give concrete its long-term strength and durability.
Portland pozzolana cement – It is produced by inter-grinding ordinary portland cement clinker with 15 % to 40 % of the pozzolana material. Pozzolana is defined as a siliceous or siliceous and aluminous material which in itself possesses little or no cementitious value but in finely divided form and in the presence of moisture, chemically reacts with calcium hydroxide at ordinary temperatures to form compounds possessing cementitious properties. Natural pozzolanic materials are volcanic ash while the industrial pozzolanic materials are fired clay, rice husk ash etc. It is essential that pozzolana be in finely divided state as it is only then that silica can combine with calcium hydroxide (produced by the hydrating portland cement) in the presence of water to form stable calcium silicates which have cementitious properties. They are similar to those of portland blast furnace cement. Portland pozzolana cement produces low heat of hydration and offer higher resistance to the attack of the aggressive water than ordinary portland cement. It is used in the mass construction works and in marine environments as well as in hydraulic works.
POSEC method – The acronym POSEC stands for Prioritize, Organize, Streamline, Economize, and Contribute. It is a time management technique which prioritizes tasks by organizing, streamlining, economizing, and contributing. It is a structured approach that helps individuals manage their time and resources effectively by focusing on what is the most important, then optimizing the way tasks are handled. Prioritize is to identify and rank one’s goals and tasks based on their importance and urgency. Organize is to plan how one is going to tackle the prioritized tasks, scheduling them effectively. Streamline is to simplify and to optimize the tasks which are necessary but not directly related to one’s main goals. Economize is to allocate time for activities which bring one joy and help one to recharge. Contribute is to use one’s managed time to give back to the community or society. By following these steps, the POSEC method aims to improve productivity, improve focus, and create a more balanced and fulfilling work-life dynamic. It is a framework which encourages individuals to think strategically about how they allocate their time and resources.
Poseidon framework – It includes a participative and an analytical design method. The participative phase uses a clean sheet approach and starts by constructing a business case table which captures all the business cases represented by a process. Afterward, an analytical design phase is followed where scheduling functions are derived from the business case table and are used to build the structure of a process.
Poseidon pump – It is a rotodynamic pump with one single shaft which needs two mechanical seals. This pump uses an open-type axial impeller. It can be described as a cross between an axial compressor and a centrifugal pump.
Posistor – It is a positive temperature coefficient resistor (PTCR thermistor) which increases its resistance sharply with temperature rise, functioning as a current-limiting device in electrical circuits to protect against overcurrent conditions.
Positional tolerance – It is a three-dimensional zone where the centre, axis, or centre plane of a feature of size (like a hole or pin) is allowed to vary from its theoretically exact location, known as true position. This tolerance, a geometric dimensioning and tolerancing (GD&T) control, uses basic dimensions to establish the true position and is represented by a symbol on engineering drawings to specify the allowable deviation for manufacturing purposes.
Positron emission tomography (PET) – It is a non-invasive, functional imaging technique which uses radiotracers and specialized detectors to create 3D maps of metabolic activity or molecular processes within an object or organism. The engineering principles involved in positron emission tomography include the design and operation of the positron emission tomography scanner’s detector arrays, the development of sophisticated image reconstruction algorithms for generating 3D images from photon data, and the engineering of radiochemistry for creating the positron-emitting radiotracers.
Position sensitive detector (PSD) – It is also called position sensitive device. It is an optical position sensor (OPS) which can measure a position of a light spot in one or two-dimensions on a sensor surface. Position sensitive detectors can be divided into two classes which work according to different principles: In the first class, the sensors have an isotropic sensor surface which supplies continuous position data. The second class has discrete sensors in a raster-like structure on the sensor surface which supply local discrete data.
Position-sensitive proportional counter (PSPC) – It is a type of detector which not only measures the energy and time of an incident particle or photon but also its position within the detector. This is achieved by extracting spatial information from the proportional counter’s response, typically using a resistive anode or a charge division method. Position-sensitive proportional counters are valuable for imaging and spectroscopy applications, particularly in fields like X-ray astronomy, nuclear physics, and materials science.
Position-sensitive proportional detector (PSPD) – It is a type of detector that provides information about the position of an incident particle or radiation along a specific dimension, while also producing an output signal proportional to the energy of the detected radiation. It is essentially a proportional counter that incorporates position-sensing capabilities.
Position sensor – It is a sensor in a conveyor system which detects the position of materials, demanding regular inspections for accurate sensing and responsiveness.
Position vector – It is a Euclidean vector which represents a point ‘P’ in space. Its length represents the distance in relation to an arbitrary reference origin ‘O’, and its direction represents the angular orientation with respect to given reference axes. It is normally denoted ‘x’, ‘r’, or ‘s’, it corresponds to the straight-line segment from ‘O’ to ‘P’.
Positive-contact bushing – It is a bushing, the inside diameter of which has direct contact with the outside diameter of a shaft or sleeve. Radial or axial clearances are provided in the housing.
Positive-contact seal – It is a seal, the primary function of which is achieved by one surface mating with another. Examples include lip, circumferential, and face-type seals.
Positive control – It is a known condition or system designed to produce an expected positive result, which verifies that the experimental method or device is capable of producing that specific outcome. It acts as a baseline, ensuring the equipment, reagents, and procedures are functioning correctly and detecting a signal as intended. If the positive control does not yield the expected outcome, it indicates a fault in the experimental setup rather than a problem with the test subject.
Positive crankcase ventilation system – It is used to prevent air pollution caused by gases being emitted from the crankcase. This system supplies fresh filtered air to the crankcase through the air intake hose. The system is positive ventilation type. It can abstract crankcase’s inner mixture gas into engine inlet pipe at proper time by means of engine inlet pipe’s vacuum performance. Hence, the mixture gas can get combustion again, which protects environment. When the engine is operating, the inlet pipe’s vacuum affects positive crankshaft ventilation valve, it makes fresh air come into air cylinder by means of air cleaner and air soft pipe, and then enter into crankcase by means of cylinder shroud. In crankcase, fresh air is mixed in mixture gas, and then the mixed gas will enter into inlet pipe by means of air cylinder shroud and positive crankshaft ventilation valve. At last, the mixed gas is combusted in engine.
Positive crowned pulley – It is a pulley which is designed with an upward curve at both ends converging toward the centre of a conveyor, aiding in the proper alignment and tracking of the conveyor belt.
Positive discharge elevators – These elevators are similar to the centrifugal discharge type excepting that the buckets are side-mounted on two strands of chains (i.e. buckets lie between two strands of chains), and are provided with a pair of two snub sprockets under the head sprockets to invert the buckets for complete discharge. The speed of the elevator can be slow in the range of 0.6 meters per minute to 0.67 meters per minute. These elevators are used for light, fluffy, sluggish and slightly sticky materials. The feeding is through scooping or digging by the buckets. An inclined elevator is particularly suitable for perfect gravity discharge.
Positive-displacement pump – It makes a fluid move by trapping a fixed amount and forcing (displacing) that trapped volume into the discharge pipe. Some positive-displacement pumps use an expanding cavity on the suction side and a decreasing cavity on the discharge side. Liquid flows into the pump as the cavity on the suction side expands and the liquid flows out of the discharge as the cavity collapses. The volume is constant through each cycle of operation. Positive-displacement pumps, unlike centrifugal, can theoretically produce the same flow at a given rotational speed no matter what the discharge pressure. Hence, these pumps are constant flow machines. However, a slight increase in internal leakage as the pressure increases prevents a truly constant flow rate. A positive-displacement pump is not to operate against a closed valve on the discharge side of the pump, because it has no shutoff head like centrifugal pumps. A positive-displacement pump operating against a closed discharge valve continues to produce flow and the pressure in the discharge line increases until the line bursts, the pump is severely damaged, or both. A relief or safety valve on the discharge side of the positive-displacement pump is hence necessary. The relief valve can be internal or external. The internal valve is normally used only as a safety precaution. An external relief valve in the discharge line, with a return line back to the suction line or supply tank, provides increased safety.
Positive electrode – It is defined by its higher electrical potential compared to the negative electrode, serving as the terminal where reduction (gain of electrons) occurs in an electrochemical cell like a battery, and is the anode during charging. While it is sometimes called the cathode in a battery context, its defining characteristic is its relatively higher electrical potential, acting as the electrode with the most positive charge or the most positive potential.
Positive error -It occurs when a measured or predicted value is consistently higher than the true or actual value. This type of error indicates that the measurement is overestimated, leading to a reading which is higher than it is to be. It can arise from systematic factors, such as instrumental imperfections or flawed experimental techniques, and is frequently corrected by subtracting the magnitude of the error from the measured value.
Positive eye-piece – It is an eye-piece in which the real image of the object is formed below the lower lens elements of the eye-piece.
Positive feedback – It is feedback from the output of a system which tends to increase the effect of an input. If overdone, leads to instability.
Positive feedback loop – It amplifies a system’s output, creating a self-reinforcing effect where a small change leads to a larger, similar change, ultimately destabilizing the system by driving it away from its initial state. Unlike negative feedback which stabilizes, positive feedback leads to exponential growth or acceleration. This can be seen in applications like oscillators and triggers in electronics, or uncontrolled reactions like nuclear fission.
Positive frequency – It refers to frequencies above zero, representing the standard measure of cycles per second (Hertz) in the frequency spectrum of real-world signals, which are inherently positive. It also can refer to the mathematically derived positive-frequency components in a Fourier analysis of a signal, which correspond to the counter-clockwise rotation of a phasor representing the signal’s positive phase shift over time.
Positive integer – It is a whole number higher than zero (1, 2, 3, and so on). These numbers are also known as natural numbers or counting numbers and are fundamental in applications such as calculating quantities, representing sizes, and defining discrete quantities in different systems.
Positive pressure – It is when an enclosed space’s pressure is higher than its surroundings, forcing its contents to flow outwards and preventing external contaminants from entering. This principle is applied in applications like cleanrooms and protective rooms to keep airborne particles out, or in material handling systems to convey solids.
Positive replica – It is a replica whose contours correspond directly to the surface being replicated.
Positive temperature coefficient (PTC) – It refers to the materials which experience an increase in the electrical resistance when their temperature is raised. Materials which have useful engineering applications normally show a relatively rapid increase with temperature, i.e., a higher coefficient.
Positron annihilation (PA) technique – It is a method which detects microstructural defects in materials, where a positron beam interacts with vacancy-type defects, resulting in variations in positron lifetime and changes in two-photon angular correlation or Doppler broadening profiles. This technique is particularly useful for assessing differences in microstructure related to plastic deformation, fatigue, and irradiation damage in metals.
Positron source – It is a device which generates positrons, which are increasingly utilized in material diagnostics.
Possible reserves – It is the valuable mineralization not sampled enough to accurately estimate its tonnage and grade, or even verify its existence. It is also called ‘inferred reserves’.
Post – In structural engineering, it is a main vertical or leaning support in a structure similar to a column or pillar, the term post normally refers to a timber but can be metal, concrete, or stone.
Post buckling analysis – It refers to the study of structural behaviour after initial buckling occurs, utilizing numerical techniques to assess stability and response, typically involving the introduction of initial imperfections and the use of master-slave node techniques to model delaminated surfaces.
Post-combustion – It refers to processes which occur after the initial burning of fuel, very frequently the separation and capture of carbon di-oxide (CO2) from exhaust or flue gases. This involves treating the gas stream after combustion to isolate specific components, frequently using chemical solvents or adsorbents, and is a widely applicable method for retrofitting existing power plants and industrial facilities without extensive modification to the combustion process itself.
Post-combustion capture (PCC) – It is a carbon capture technology which separates and removes carbon di-oxide (CO2) from industrial flue gases after fuel has been burned. The process involves capturing carbon di-oxide from the exhaust gases of sources like coal or natural gas power plants using methods such as chemical absorption with solvents, physical adsorption, membrane separation, or other chemical reactions. This carbon di-oxide is then compressed and sent for storage or utilization to prevent its release into the atmosphere.
Post-combustion chamber – It is a section of a combustion system, frequently following a primary chamber, designed to complete the combustion of fuel and unburnt products, ensure complete reaction, and manage exhaust gases at sufficient temperatures and residence times to comply with environmental regulations. It is used in systems like incinerators, waste-to-energy plants, and industrial furnaces to achieve high temperatures and optimal gas mixing, minimizing pollutants in the exhaust stream before release or further processing.
Post-consumer scrap – It is also called old scrap. Post consumer scrap results when industrial and consumer steel products (such as automobiles, appliances, buildings, bridges, ships, cans, and railroad coaches and wagons, etc.) have served their useful life. Post consumer scrap is collected after a consumer cycle, either separately or mixed, and it is frequently contaminated to a certain degree, depending highly on its origin and the collection systems. Since the life time of several products can be more than ten years and sometimes even more than 50 years (for example products of building and construction), there is an accumulation of steel products in use since the production of the steel has started on a large scale. Old steel scrap accounts for around 48 % of total scrap.
Post cure – It is additional elevated-temperature cure, normally without pressure, to improve final properties and / or complete the cure, or decrease the percentage of volatiles in the compound. In certain resins, complete cure and ultimate mechanical properties are attained only by exposure of the cured resin to higher temperatures than those of curing.
Posteriori articulation – It refers to methods which involve the expression and adjustment of preferences after evaluating potential solutions, allowing for a refined decision-making process based on the outcomes observed.
Posteriori distribution – It is the updated probability distribution of a parameter after considering new evidence, calculated using Bayes’ theorem to modify the prior probability distribution based on observed data.
Posteriori error – It refers to evaluative tools which assess the accuracy of numerical solutions to partial differential equations after computation, enabling practitioners to refine solutions based on error distributions.
Posterior probability – It is the updated probability of an event’s occurrence after new data or evidence has been considered. It is a core concept in Bayesian inference, where a prior probability (initial belief) is refined by new observations using Bayes’ theorem to produce a more accurate, or posterior, probability. For example, an engineer can use posterior probabilities to update the likelihood of an error in a predictive model after analyzing additional sensor readings.
Post failure behaviour – It describes the mechanical response and characteristics of a material, component, or structure after it has reached its peak strength and undergone fracture or substantial deformation. This includes how the material’s load-carrying capacity, deformation, and stress distribution change beyond the point of failure, influencing system reliability, structural stability, and the potential for beneficial load redistribution or detrimental unstable failure propagation.
Post forming – It is the forming, bending, or shaping of fully cured, C-staged thermoset laminates which have been heated to make them flexible. On cooling, the formed-laminate retains the contours and shape of the mould over which it has been formed.
Post forming heat treatable (PFHT) steel – Post forming heat treatment is a general method to develop an alternative higher strength steel. The major issue holding back widespread implementation of high strength steel (HSS) typically has been maintaining part geometry during and after the heat treatment process. Fixturing the part and then heating (furnace or induction) and immediate quenching appear to be a solution with production applications. In addition, the stamping is formed at a lower strength and then raised to a much higher strength by heat treatment. One process is water quenching of inexpensive steels with chemistries which allow in part strengths in the range of 900 MPa to 1,400 MPa of tensile strength. Another process is air-hardening of alloyed tempering steels which feature very good forming properties in the soft-state (deep-drawing properties) and high strength after heat treatment (air-hardening).
Post-heating – It is the heating weldments immediately after welding, for tempering, for stress relieving, or for providing a controlled rate of cooling to prevent formation of a hard or brittle structure.
Post hoc test – The post hoc test (or post hoc comparison test) is used at the second stage of the analysis of variance (ANOVA) or multiple analyses of variance (MANOVA) if the null hypothesis is rejected.
Post-hoc theorizing – Post hoc theorizing is likely to occur when the analyst attempts to explain analysis results after-the-fact. In this second-rate approach to scientific discovery, the analyst develops hypotheses to explain the data, instead of the converse (collecting data to nullify the hypotheses). The number of post-hoc theories which can be developed to ‘fit’ the data is limited only by the imagination of a group of people. With an abundance of competing hypothesis, and little forethought as to which hypothesis can be afforded more credence, there is little in the way of statistical justification to prefer one hypothesis to another. More importantly, there is little evidence to eliminate the prospect of illusory correlation.
Post-industrial waste – It consists of by-products of the manufacturing process, such as trimmings in the production of steel. These waste products are frequently put back into the manufacturing process and called ‘recycling’. Several dispute whether this truly constitutes recycling or simply good business practices.
Post-nucleation – It is the step where, if necessary, the catalyst is converted to its final form when plating on plastic substrates. This is the final step prior to electroless plating.
Post purge – It is a method of scavenging the furnace and boiler passes to remove all combustible gases after flame failure controls have sensed pilot and main burner shut-down and safety shut-off valves are closed.
Post-sintering – It refers to any secondary processing performed on a powder-based part after the initial sintering process, which fuses particles at a temperature below melting point. Common post-sintering techniques, such as hot isostatic pressing (HIP), infiltration, machining, and coating, are used to reduce porosity, improve mechanical properties, improve surface finish, and achieve desired final dimensions.
Post tensioning device – It refers to any equipment used in the post-tensioning method of concrete construction, which involves tensioning high-strength steel tendons after the concrete has cured to introduce a compressive force which improves the structure’s strength and durability. Key devices include hydraulic jacks to stretch the tendons, anchoring devices to secure the tensioned tendons to the concrete, and sometimes couplers to connect tendon segments. Other essential components in the overall system are the ducts or sleeves which house the tendons and the grouting equipment to fill the ducts after tensioning.
Post treatment – It is subjecting the steel to specific processes after it has been galvanized.
Post weld artificial aging – It highly improves the joint strength with the ultimate tensile strength reaching 87.3 % of the base metal.
Post-weld heat treatment – It is a heat treatment which follows the welding operation.
Pot – It is a vessel for holding molten metal. It is the electrolytic reduction cell used to make such metals as aluminum from a fused electrolyte.
Pot annealing – It is annealing a metal or alloy in a sealed container under conditions which minimize oxidation. In pot annealing a ferrous alloy, the charge is normally heated slowly to a temperature below the transformation range, but sometimes above or within it, and is then cooled slowly. This process is also called close annealing or pot annealing.
Potable water – It is also called drinking water. It is the water which is provided by a water treatment plant and is used for drinking, cooking, dishwashing, or other domestic purposes needing water which is suitable for human consumption.
Potash – It consists of potassium compounds which are mined for fertilizer and for use in the chemical industry.
Potash feldspar – It is an alkali alumino-silicate mineral with the chemical formula KAlSi3O8, distinguished by its high potassium content. It functions as a fluxing agent, lowering melting temperatures and improving the strength and finish of various materials, particularly in the ceramics and glass industries. Beyond its role as a flux, potash feldspar’s silicon and aluminum content make it an important component in producing durable sanitary ware, tableware, and even as a filler in construction materials.
Potassium (K) – It is a chemical element having atomic number 19. It is a silvery white metal which is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to form flaky white potassium per-oxide in only seconds of exposure. It is one of the alkali metals, all of which have a single valence electron in the outer electron shell, which is easily removed to create an ion with a positive charge (which combines with anions to form salts). In nature, potassium occurs only in ionic salts. Elemental potassium reacts vigorously with water, generating sufficient heat to ignite hydrogen emitted in the reaction, and burning with a lilac-coloured flame.
Potassium-ion battery – It is an energy storage system which stores and releases electrical energy by moving Potassium ions (K+) between its positive and negative electrodes, similar to a lithium-ion battery but using potassium instead of lithium. Potassium-ion batteries are a promising, sustainable alternative to lithium-ion batteries due to the earth’s abundant potassium reserves and potential for lower material costs, though they are still in early development stages, facing challenges like volume expansion during cycling and slower reaction kinetics.
Potassium sulphate (K2SO4) – It is an inorganic, white, crystalline salt known as sulphate of potash or arcanite. It is an ionic compound made of potassium cations (K+) and sulfate anions (SO4)2-, which readily dissolves in water but not ethanol. It is found naturally in minerals and volcanic lava. It is used in fertilizers, and other industrial applications.
Potassium titanates – These are a family of synthetically produced ceramic compounds of potassium (K2O) and titanium dioxide (TiO2), characterized by their layered or tunnel-like crystalline structures. Different forms, such as K2Ti6O13 or K2Ti8O17, possess diverse properties like high thermal stability, electrical insulation, mechanical strength, and chemical resistance, leading to applications as additives in electronics, composites, and even wastewater treatment.
Potential – It is the quantity of work needed to move a unit positive charge from a reference point (typically infinity) to a specific point in an electric field, without acceleration. It is a scalar quantity representing the potential energy per unit charge at a given location within an electric field, with its unit of measurement being the volt (V). It also consists of different functions from which intensity or velocity at any point in a field can be calculated. It is the driving influence of an electro-chemical reaction.
Potential difference – It is a voltage difference, the quantity of work needed to bring a test charge from one point to another divided by charge magnitude.
Potential divider – It is also called voltage divider. It is an electrical circuit which produces an output voltage which is a fraction of its input voltage by distributing the voltage across two or more resistors in series. The fundamental principle is Ohm’s Law, which states that the voltage-drop across a resistor is proportional to its resistance, allowing the input voltage to be divided as per the ratio of the resistances in the series combination.
Potential divider circuit – It is a configuration which converts changes in resistance, such as those from a thermistor, into proportional voltage changes by applying a constant voltage across two resistors in series. The output voltage is determined by the ratio of the resistances in the circuit.
Potential deposit – It is a deposit which has not yet been demonstrated to exist by direct evidence (e.g., drilling and / or sampling), but is assessed as potentially existing based primarily on indirect evidence (e.g. surface or airborne geophysical measurements).
Potentially economic – The reference point at which Reserves are defined, normally the point where the ore is delivered to the processing plant, is to be stated. It is important that, in all situations where the reference point is different, such as for a saleable product, a clarifying statement is included to ensure that the reader is fully informed as to what is being reported. Quantities, reported in tons / volume with grade / quality, demonstrated by means of a Pre-feasibility study, Feasibility study or Mining report, in order of increasing accuracy, not justifying extraction under the technological economic, environmental, and other relevant conditions, realistically assumed at the time of the determination, but possibly so in the future. The term potentially economic comprises both marginal and sub-marginal. These two sub-categories are for optional use on a national level.
Potential energy – It is the stored energy in a body or in a system because of its position in a force field or because of its configuration.
Potential exergy – It is the work obtainable from a system’s state, such as its position or chemical composition, because of a disparity with its environment that allows it to perform work.
Potential-pH diagram – It is a graph of the redox potential of a corroding system against the pH of the system, compiled using thermodynamic data and the Nernst equation. The diagram shows regions within which the metal itself or some of its compounds are stable.
Potentially Viable projects – Potentially Viable projects are potential future recovery by mining operations, where development is pending or on-hold.
Potential source – It is a source which has not yet been demonstrated to exist by direct evidence, but is assessed as potentially existing based primarily on indirect evidence.
Potential transformers – Potential transformers are used with volt-meters, watt-meters, watt-hour meters, power-factor meters, frequency meters, synchroscopes and synchronizing apparatus, protective and regulating relays, and undervoltage and overvoltage trip coils of circuit breakers. One potential transformer can be used for a number of instruments, if the total current needed by the instruments connected to the secondary winding does not exceed the transformer rating. Potential transformers are usually rated 50 volt-amperes to 200 volt-amperes at 120 secondary volts. The secondary terminals are never to be short circuited since a heavy-current results, which can damage the windings.
Potentiometer – It is a three-terminal variable resistor, which can be configured as an adjustable voltage divider. It is an instrument which measures electromotive force by balancing against it an equal and opposite electromotive force across a calibrated resistance carrying a definite current.
Potentiodynamic (potentiokinetic) – It is the technique for varying the potential of an electrode in a continuous manner at preset rate.
Potentiodynamic polarization tests – These are defined as techniques used to measure the corrosion rate of samples by applying a potential difference between reference and working electrodes and measuring the resulting current, which indicates the corrosion occurring on the working electrode in terms of current density. This method helps establish the active / passive corrosion rate at different potentials and is particularly relevant for analyzing pitting corrosion.
Potentiometer – It is a three-terminal device used either as a variable resistor to control electrical resistance and current flow, or as a voltage divider to adjust voltage levels. It works by using a movable contact, called a wiper, which slides along a resistive element to vary the resistance ratio and thus the output voltage. Potentiometers are also used in electronics to measure electromotive force (EMF), compare cell electromotive forces, and as voltage regulators in different devices, such as volume controls on audio equipment.
Potentiometric – It refers to a method in electroanalytical chemistry used to determine the concentration of a solute in solution by measuring the potential difference between a reference electrode and a measuring electrode within an electrochemical cell.
Potentiometric membrane electrodes – These are electro-chemical devices which can be used to quantify numerous ionic and non-ionic species. This class of electro-chemical sensors can be divided into ion-selective and gas-sensing membrane electrodes. In both the cases, a selective membrane potential is related to the concentration or activity of the species of interest. Potentiometric membrane electrode measurements require an indicating electrode and a reference electrode. The potential of the indicating electrode depends on the activity of the ion of interest, and this potential is measured with respect to the constant potential of the reference electrode using a high-impedance potentiometer. The reference electrode is an important but frequently overlooked component of potentiometric membrane electrode measurement.
Potentiometry – It is defined as the measurement of electrical potential (also designated electromotive force) between two electrodes when the cell current is zero.
Potentiostat – It is an instrument which automatically maintains an electrode in an electrolyte at a constant potential or controlled potentials relative to a suitable reference electrode.
Potentiostatic – It is the technique for maintaining a constant electrode potential.
Potentiostatic etching – It consists of anodic development of microstructure at a constant potential. Adjusting the potential makes possible a defined etching of singular phases.
Pot life – It is the length of time which a catalyzed thermosetting resin system retains a viscosity low enough to be used in processing. It is also called working life.
Poultice corrosion – It is a term used in the automotive industry to describe the corrosion of vehicle body parts because of the collection of road salts and debris on ledges and in pockets which are kept moist by weather and washing. It is also called deposit corrosion or attack.
Pour – It is the discharge of molten metal from the ladle into the mould.
Pourbaix (potential-pH) diagram – It is a graph of the redox potential of a corroding system against the pH of the system, compiled using thermodynamic data and the Nernst equation. The diagram shows regions within which the metal itself or some of its compounds are stable.
Poured short – It is the casting which lacks completeness because of the cavity not being filled with molten metal.
Pouring – It is the transfer of molten metal from furnace to ladle, ladle to ladle, or ladle into moulds. It is filling the mould with molten metal.
Pouring basin – In metal casting, it is a basin or reservoir on top of a mould which receives the molten metal before it enters the sprue or down-gate.
Pouring basin, cup – It is located on top of sprue or down gate. It is that portion of the gating.
Pouring cup – It is the flared section of the top of the down sprue. It can be shaped by hand in the cope, or be a shaped part of the pattern used to form the down sprue, or it can be baked core cup placed on the top of the cope over the down sprue.
Pouring device – It is mechanically operated device with a ladle set for controlling the pouring operation.
Pouring ladle – It is the ladle used to pour metal into the mould.
Pouring off – It is the task of ladling, or mechanically pouring, of the molten metal into the moulds, forming the casting.
Pouring pit refractory – It is a refractory which is associated with the transfer or flow control of molten steel between furnace and the mould.
Pouring refractories – These are refractories which are used for the transfer of steel from furnace to ingot. Refractories include ladle brick, nozzles, sleeves, stopper heads, mold plugs, hot tops, and mortars used for the brickwork involved.
Pouring temperature – It refers to the specific temperature at which a molten material, like metal or concrete, is poured into a mould during the casting process. It is a critical parameter in casting as it affects the fluidity of the material, solidification time, and ultimately the quality of the finished product.
Pour point – It is the lowest temperature at which a lubricant can be observed to flow under specified conditions. Pour point of oil is an important quality. It is a temperature at which oil still remains fluid. It reflects on the capability of the oil to work at low temperatures.
Pour-point depressant – It is an additive which lowers the pour point of a lubricant.
Powder – It is an aggregate of discrete particles which are normally in the size range of 1 micrometer to 1,000 micrometers.
Powder adhesion – In dry process enameling, it is the ability of an electrostatic powder to remain attached by static attraction to a grounded substrate.
Powder bed – It is a layer of powder material, such as metal or plastic, which serves as the feedstock for additive manufacturing processes like powder bed F]fusion (PBF). In these processes, a heat source, like a laser or electron beam, selectively fuses particles within the powder bed, layer by layer, to build a three-dimensional object.
Powder bed fusion (PBF) – It is an additive manufacturing process which creates three-dimensional objects by fusing powder particles together layer by layer using a heat source, such as a laser or electron beam. Core principle is that a thin layer of powder material (metal, plastic, or ceramic) is spread across a build platform. A focused energy source (laser or electron beam) selectively melts or sinters the powder, fusing it together according to a pre-defined 3D model. This process is repeated layer by layer until the entire object is formed. This technology allows for the creation of complex geometries and is used in several industries.
Powder blending – It is a unit operation and manufacturing process of mixing two or more dry powders to achieve a uniform and homogeneous distribution of their particles, ensuring consistent product quality and performance. This technique is widely used in industry, where precise composition is crucial for accurate dosing, composite material properties, or desired product characteristics. The process can involve different methods of dry mixing, including convection, diffusion, and shear, but faces challenges like particle segregation and agglomeration which are to be managed to create a truly uniform blend.
Powder coating – It is the application of an even layer of colour to aluminum extrusions by spraying powdered paint using an electrostatic process then baking on (stove enameling).
Powder cutting – The preferred terms are chemical flux cutting and metal powder cutting. It is a technique which supplements an oxy-fuel torch with a stream of iron or blended iron-aluminum powder to facilitate flame cutting of difficult-to-cut materials. The powdered material propagates and accelerates the oxidation reaction, as well as the melting and spalling action of the materials to be cut.
Powder designation – It consists of a code number identifying a specific powder.
Powdered coal – It is finely ground, high-volatile coal used for heating furnaces and annealing ovens in the malleable foundry industry.
Powder extrusion – It is a manufacturing process where a mixture of powder and a binder is forced through a die to create a desired shape. This process is frequently used in powder metallurgy and for creating components from different materials like metals, ceramics, and plastics. The resulting shape, known as an extrudate, is then typically subjected to further processing like debinding and sintering to achieve the final product’s desired properties.
Powder fill – It is the filling of a die cavity with powder.
Powder flame spraying – It is a thermal spraying process variation in which the material to be sprayed is in powder form.
Powder flow meter – It is an instrument for measuring the rate of flow of a powder as per a specified procedure.
Powder forging – It is also called powder metallurgy forging. It is the plastic deformation of a powder metallurgy compact or preform into a fully dense finished shape by using compressive force. It is normally done hot and within closed dies.
Powder lubricant – In powder metallurgy, it is an agent or component incorporated into a mixture to facilitate compacting and ejecting of the compact from its mould.
Powder metallurgy (P/M) – It is the technology and art of producing metal powders and utilizing metal powders for production of massive materials and shaped objects.
Powder metallurgy (PM) method – It is a solid-phase manufacturing process which involves weighing, mixing, compacting, and sintering graded powder materials to produce fully dense materials, particularly for fabricating functionally graded materials (FGMs) with complex shapes and enhanced properties.
Powder metallurgy part – It is a shaped object which has been formed from metal powders and sintered by heating below the melting point of the major constituent. A structural or mechanical component made by the powder metallurgy process.
Powder metallurgy tool steels – Powder metallurgy has become a major process for the manufacture of high-performance tool steels and tool steel products. The items now available include as-compacted or hot-worked billets and bars, semifinished parts, near-net shapes, and indexable cutting tool inserts. The powder metallurgy process has been used primarily for the production of advanced high-speed tool steels. However, it is now also being applied to the manufacture of improved cold-work and hot-work tool steels. For majority of applications, the powder metallurgy tool steels offer distinct advantages over conventional tool steels.
Powder metals – These are alloys processed into a fine, grain-like powder through one of several processes. These are mainly made from stainless steel, brass, copper, iron, or bronze, these metals can be blended with other alloys to achieve the desired material properties and characteristics for a particular application. These offer higher flexibility in material usage and mechanical properties, powder metal parts can be highly customized and easily reproduced while yielding high-strength, cost-effective components.
Powder method – It is a method of X-ray diffraction involving a poly-crystalline and preferably randomly oriented powder sample and a narrow beam of the mono-chromatic radiation.
Powder production – It is the process by which a powder is produced, such as machining, milling, atomization, condensation, reduction, oxide decomposition, carbonyl decomposition, electrolytic deposition, or precipitation from a solution.
Powder rolling – It is also called roll compacting, or rolled compaction. It consists of the progressive compacting of metal powders by the use of a rolling mill.
Powder technology – It is a broad term encompassing the production and utilization of both metal and non-metal powders.
Powder rolling mill – In the powder rolling mill, metal powder is introduced between the rolls and compacted into a ‘green strip’, which is subsequently sintered and subjected to further hot-working and / or cold working and annealing cycles.
Power – It is the quantity of energy transferred or converted per unit time. In the International System of Units, the unit of power is the watt, equal to one joule per second. Power is a scalar quantity. Specifying power in particular systems can need attention to other quantities, e.g., he power involved in moving a ground vehicle is the product of the aerodynamic drag plus traction force on the wheels, the velocity of the vehicle. The output power of a motor is the product of the torque that the motor generates and the angular velocity of its output shaft. Similarly, the power dissipated in an electrical element of a circuit is the product of the current flowing through the element and of the voltage across the element. In electrical engineering, it is the rate of transfer of electrical energy within a circuit. Its SI (International System of Units) unit is the watt, the general unit of power, defined as one joule per second. Electric power is normally produced by electric generators, but can also be supplied by sources such as electric batteries. It is normally supplied by the electric power industry through an electrical grid. Electric power can be delivered over long distances by transmission lines and used for applications such as motion, light, or heat with high efficiency. In case of statistics, in general, the power of a statistical test of some hypothesis is the probability which it rejects the alternative hypothesis when the alternative is false. The power is greatest when the probability of a Type II error is least. Power is 1-beta, whereas level of confidence is 1-alpha.
Power and free conveyor – These conveyors are basically a special design of the ‘load-propelling or pusher trolley’ conveyors. In a normal pusher trolley conveyor the non-powered trolleys, supported from a monorail, carry the load and are pushed by dogs / pushers attached to the chain trolleys mounted on a separate track. A power and free conveyor is one in which the power trolleys run directly above the free trolleys, which run in double channel track, and arrangements are made such that at desired points the non-powered load carrying trolleys can be engaged to or disengaged from the power trolleys. The power trolley dogs / pushers are rigid attachments on the trolleys or chain. They engage or disengage with the free trolleys by switching them in from a branch line to the mainline, and by horizontal turns and vertical curves in the power line. The switching operations can be made mechanically or through actuation of pneumatic cylinder synchronous with movement of power trolleys.
Power balance – It refers to the fundamental principle which, within a given system, the total energy or power generated equals the total energy or power consumed, plus any energy or power lost or stored. This principle is applied to various engineering fields, such as electrical power grids, to ensure stability by matching supply and demand, and in circuit analysis to verify the correctness of calculations. It can also be understood in the context of renewable energy systems to assess the net energy production against consumption.
Power belt curve – It is a curve conveyor which is guided by tapered pulleys that use a belt.
Power BJT – It is a bipolar junction transistor (BJT) which can be used in circuits handling a watt or more of power.
Power cables – Power cables are used for distribution and transmission of electrical energy. These cables are assembly of one or more individually insulated flexible electrical conductors, normally held together with an overall sheath which is used to transmit electric power. Power cable can be considered to be just a conductor, overlying insulation, and frequently an exterior shield or jacket. It is used to convey electric power. It is the purpose of the cable to convey the electric current to the intended device or location. In order to accomplish this, a conductor is provided which is adequate to convey the electric current imposed. Equally important is the need to keep the current from flowing in unintended paths rather than the conductor provided. Electrical insulation (dielectric) is provided to largely isolate the conductor from other paths or surfaces through which the current can flow. Hence, it can be said that any conductor conveying electric signals or power is an insulated conductor.
Power conditioner – It is a system which is intended to alter some property of the bulk power supply to improve it for some application. Examples are filters, surge suppressors, voltage regulators, uninterruptible power supplies, and several others.
Power consumption – It is the rate at which the electrical energy is consumed.
Power conversion – It is the efficient process of changing electrical energy from one form to another, such as altering its voltage, current, or alternating current / direct current nature, to match the requirements of a particular device or system. This conversion is performed by power converters, which are electronic devices or systems important for applications ranging from consumer electronics and renewable energy to electric vehicles and micro-grids.
Power converter – It is a device which is intended to convert electric power to another form of electric power, such as conversion between alternating current and direct current or changing frequency or phase number.
Power conveyor – It is a conveyor system which needs power to operate and move packages.
Power coupling – It is any device which connects a power source to a load, enabling the transmission of power from one component to another. This can involve transferring mechanical power between two shafts using shaft couplings, or it can refer to systems which convert energy between different forms (electrical, mechanical, hydraulic) to achieve efficient power synergy.
Power density – It is a measure of how much power can be generated or stored in a given volume or mass. It is frequently expressed as watts per unit volume or watts per unit mass. Essentially, it indicates how ‘powerful’ a system is relative to its size or weight.
Power distribution – It is the portion of an electrical grid which is between the sub-station or bulk supply and the end consumer.
Power-driven hammer – It is a forging hammer with a steam or air cylinder for raising the ram and augmenting its downward blow.
Powered air-purifying respirator (PAPR) – It is a battery-operated respiratory protection system which uses a fan to draw contaminated air through a filter or cartridge, purifying it before supplying it to a facepiece, hood, or helmet. This system provides a higher level of protection and comfort compared to basic N95 masks by delivering clean, filtered air to the wearer, reducing breathing resistance.
Powered feeder – It is the mechanized section of a conveyor system responsible for transferring products from a horizontal orientation to an inclined position through powered movement.
Powered roller conveyor – It is a conveyor which at uses powered rollers to move materials. It is a conveyor system with rollers powered by a central drive unit, demanding regular inspections for roller health, motor functionality, and overall system performance. It is also called live roller conveyor. In this type of roller conveyor, all or a selected number of rollers are driven by one or a number of motors depending on the selected drive arrangement. The driven rollers transmit motion to the loads by friction. The powered roller conveyors can be installed at a slightly inclined position, up to 10-degree up or up to 17-degree down. The load can be moved in either direction by changing the direction of rotation of the rollers, where these are called reversing conveyors. Powered roller conveyors are intensively used in heavy process plants like rolling mills to feed heavy and at times hot metal to or to take the material in the mill to various other process equipment. The roller conveyors can be reversing type or non-reversing type.
Power electronics – It is the application of solid-state electronic devices to control, convert, and condition electric power, enabling the efficient transfer of electrical energy from one form to another. It combines principles from electrical, electronic, and control engineering to manage high voltages and currents for different loads and systems, from consumer electronics to industrial drives and power transmission.
Power engineering – It is that part of electrical engineering which deals with the generation, distribution and consumption of electrical power.
Power factor – It is the ratio of apparent power flowing to a load divided by the real power. Power factor of an alternating current power system is defined as the ratio of the real power absorbed by the load to the apparent power flowing in the circuit. Real power is the average of the instantaneous product of voltage and current and represents the capacity of the electricity for performing work. Apparent power is the product of root mean square (RMS) current and voltage. Because of the energy stored in the load and returned to the source, or because of a non-linear load that distorts the wave shape of the current drawn from the source, the apparent power may be greater than the real power, so more current flows in the circuit than would be required to transfer real power alone. A power factor magnitude of less than one indicates the voltage and current are not in phase, reducing the average product of the two. A negative power factor occurs when the device (normally the load) generates real power, which then flows back towards the source.
Power-factor correction – It is a device which is intended to bring the power factor of some load closer to 1. Power factor correction is the process of compensating for the lagging current by creating a leading current by connecting capacitors to the supply. A sufficient capacitance is connected so that the power factor is adjusted to be as close to unity as possible.
Power flow control – It refers to the management and optimization of electrical power within a network to improve stability, reduce losses, and ensure efficient utilization of resources by actively managing voltages and currents. It involves utilizing specialized devices and strategies, such as those found in flexible alternating current transmission systems (FACTS), to redirect power, prevent overloads, mitigate congestion, and maintain reliable operations in the grid.
Power-flow study – It is a numerical analysis of the flow of electric power in an inter-connected system. A power-flow study normally uses simplified notations such as a single-line diagram and per-unit system, and focuses on different aspects of alternating current power parameters, such as voltage, voltage angles, real power and reactive power. It analyzes the power systems in normal steady-state operation. Power-flow or load-flow studies are important for planning future expansion of power systems as well as in determining the best operation of existing systems. The principal information got from the power-flow study is the magnitude and phase angle of the voltage at each bus, and the real and reactive power flowing in each line.
Power fluctuation – It is a sudden or rapid change in the voltage or current of an electrical power supply, frequently caused by factors like load changes, grid instability, or faults. These variations, also known as voltage fluctuations or sometimes flicker, degrade equipment performance and can cause instability in electrical systems, especially with the integration of intermittent renewable energy sources.
Powerful tool – It is a mechanism, device, or instrument which possesses substantial strength, efficiency, or effectiveness, enabling it to amplify effort, accomplish tasks, or achieve particular results more effectively than a less effective alternative. The term can apply to physical tools like electric drills or metaphorical tools such as software, where its strength lies in its ability to provide great insights or influence.
Power generation – It is the practice of converting other energy sources to electric power.
Power generation efficiency – It is the ratio of useful electrical energy output to the total energy input from a fuel or energy source, expressed as a percentage. It quantifies how effectively a power plant converts available energy into electricity, with losses because of the friction, heat, light, noise, and vibration always making the output less than the input. The specific definition and units can vary depending on whether the efficiency is for a specific component (like a generator) or the entire power plant.
Power generation system – It is an engineered infrastructure which that converts various forms of energy into electricity through a process of energy transformation, utilizing a diverse set of components like turbines, generators, and alternators to meet the power needs of consumers. These systems are part of a larger power system, which also includes transmission and distribution networks, and are designed to provide a continuous, reliable supply of electricity from a variety of conventional and renewable sources.
Power grid – It is an inter-connected network of generators, transmission lines, and apparatus for reliable and economic transmission and utilization of electric power.
Power inductor – It is a passive electronic component, frequently a coil of wire around a core, which stores energy in a magnetic field and opposes changes in current flow, making it useful for filtering noise, smoothing voltages, and transferring energy in power supplies and converters.
Power inverter – It is an electronic device or power electronic converter which that transforms direct current (DC) into alternating current (AC). This conversion since grid-connected systems need alternating current power, which inverters provide from direct current sources like solar panels, batteries, or HVDC (high voltage direct current) transmission lines. By using electronic switches like MOSFETs (metal-oxide-semiconductor field-effect transistor). It is a field and control signals, inverters generate an alternating current output with a desired voltage and frequency, frequently using techniques like pulse width modulation (PWM) to create a pure or modified sine wave.
Power laser – It is a laser system designed to deliver high output power, typically ranging from tens of watts to hundreds of kilowatts, for applications like manufacturing, welding, and cutting. The definition centres on the laser beam power, which is the total energy emitted as light per second, and high-power lasers are characterized by technologies like fibre lasers and disc lasers which enable them to achieve the elevated power levels needed for processes such as drilling and material removal.
Power limit – It is a maximum or minimum boundary on the power (electrical or mechanical) which a device, component, or system can handle, produce, or transfer without damage, malfunction, or violating operational standards. These limits are established by manufacturers, design engineers, or system operators to ensure safety, protect equipment, maintain performance, and prevent instability in larger systems like power grids.
Power line – It is an electrical conductor, cable, or conduit which transports electrical energy from its source (like a power plant or substation) to consumers or another substation. It is a fundamental component of the power grid, consisting of one or more conductors suspended by poles or towers or buried underground, designed to transmit electricity safely and efficiently over distances.
Power-line communication – It is a technology which uses existing electrical power lines as a transmission medium for data, rather than just power. By superimposing high-frequency data signals onto the low-frequency power lines, power-line communication allows for simultaneous power distribution and data communication without the need for new communication cabling. This cost-effective approach is used for several applications, from smart grid applications like telemetry and control to automation and Internet access.
Power line protection – It refers to the set of strategies, devices, and equipment used to detect and isolate faults, such as short circuits or lightning strikes, from power transmission and distribution lines to prevent damage to the network, ensure system stability, and maintain reliable power supply. Key components include protection relays, which sense abnormal conditions, and circuit breakers, which automatically disconnect faulted sections of the line from the rest of the grid.
Power loss – It is the energy which is dissipated as heat or otherwise rendered unusable during the transfer or conversion of energy through a system, component, or process, representing a reduction in useful output power compared to the input power. This unwanted power is frequently converted into heat and lost to the environment through mechanisms like electrical resistance, friction, or magnetic effects.
Power management – It is the process of efficiently controlling and optimizing the distribution and use of electrical power within a system, electronic device, or electrical grid to improve performance, reduce energy consumption and costs, and improve reliability and availability. This involves using several techniques at different levels (from integrated circuits to entire buildings) to ensure that only necessary power is used, putting components into low-power states when inactive, and collecting data to monitor consumption and quality.
Power MOSFET – It is a metal oxide semi-conductor field effect transistor (MOFSET) which is suitable for use in circuits handling more than a watt of power.
Power of the test – It is the probability which one rejects a false null hypothesis with a particular statistical test.
Power outage – It is also called blackout. It is the interruption or loss of the electrical power supply to an end user, such as a plant, industry, or entire region. These disruptions are caused by events like natural disasters, human error, equipment failures, overloading of the grid, and cyber or physical attacks. The impact can range from inconvenience to widespread economic and societal disruption, making the analysis and mitigation of power outages a critical aspect of critical infrastructure engineering.
Power plant – It is a facility which converts other energy forms into electric power.
Power point presentation – It refers to the digital slides and files created using Microsoft’s PowerPoint software for presenting information with text, images, and multimedia elements in professional and educational settings.
Power quality – It refers to the degree to which the electricity supplied to equipment meets the desired specifications for voltage, frequency, and waveform purity, ensuring it can operate reliably without failure or misoperation. It encompasses momentary and steady-state phenomena and is crucial for the efficiency, reliability, and safety of electrical systems. Poor power quality is characterized by voltage deviations (sags, swells, transients), frequency deviations, and waveform distortions like harmonics, which can stem from natural events or non-linear loads such as electronic devices.
Power rail – It is a conductor, or a network of conductors, which serves as a path for delivering electrical power (voltage and current) to components within a system, such as electronic devices, circuit boards, cranes, or trains. These rails are important for providing the consistent, stable energy needed for a circuit or system to function, and they can be found in different forms, from the ‘third rail’ on a metro system to the copper layers on a printed circuit board (PCB).
Power rating – It is the nominal power which an equipment, a device, apparatus, or machine can handle, with specified or customary temperature rise and life expectancy.
Power ratio – Itis the comparison of two power values, often expressed as a dimensionless quantity or in decibels (dB), to indicate a gain, loss, or specific characteristic of a system or signal. Common engineering applications include the efficiency of a machine (output power against input power), the gain of an amplifier (output power against input power), and the signal-to-noise ratio (SNR) in communication systems.
Power rectifier – It is a device or circuit which converts alternating current (AC) to direct current (DC), providing a steady, unidirectional flow of electrical power for electronic devices, power supplies, and other systems which needs direct current. Rectifiers use components like diodes, which act as one-way valves for electricity, to achieve this conversion. The process of rectification is fundamental for powering several modern electronic equipments, from chargers to industrial applications.
Power restriction – It refers to a predefined limitation on the quantity of electrical, mechanical, or communication power which can be supplied to or used by a device, system, or network component. These restrictions are important for ensuring system stability, protecting equipment from damage, complying with regulations, and optimizing performance by controlling energy consumption and managing resources.
Power spectral density (PSD) – It is the measure of signal’s power content versus frequency. A power spectral density is typically used to characterize broadband random signals. The amplitude of the power spectral density is normalized by the spectral resolution employed to digitize the signal. For vibration data, a power spectral density has amplitude units of g2/hertz (‘g’ is acceleration).
Power spinning – It is also called spinning reserve. In the context of electricity generation, it refers to the online but unloaded generating capacity which is synchronized with the grid and can quickly respond to increased demand or compensate for the loss of an operating generator. This reserve capacity is essentially ‘spinning’ at the same frequency as the grid and can be brought online within minutes to maintain grid stability.
Power storage – It is a facility which changes electric power into some form which can be stored and usefully reconverted back to electric power, e.g., pumped storage or battery systems.
Power stroke – In the context of an internal combustion engine, the term power stroke is (i) a phase of the engine’s cycle (e.g. compression stroke, exhaust stroke), during which the piston travels from top to bottom or vice versa, (ii) the type of power cycle used by a piston engine, and (iii) stroke length which nis the distance travelled by the piston during each cycle. The stroke length, along with bore diameter, determines the engine’s displacement.
Power supply – It is a sub-system of a computer or other electronic device which turns electric power from a wall plug or batteries into a form suitable for use by the system.
Power-system automation – It is the implementation of power-operated switching and control which allows automatic operation of power system elements, instead of manual operation.
Power-system protection – It is the technology of limiting the spread of failures of a power system to a minimum, and of preventing permanent damage to device, equipment, apparatus, or conductors by such faults.
Power-to-heat ratio (PHR) – It is a dimensionless metric which quantifies the proportion of electricity to useful thermal energy produced by a cogeneration system (such as a combined heat and power, or CHP, unit). A higher power-to-heat ratio indicates a greater proportion of electricity produced relative to heat, while a lower power-to-heat ratio signifies more heat is generated. This ratio is a crucial factor in designing and selecting combined heat and power systems to match specific operational needs, as facilities with a lower power-to-heat ratio can benefit from systems that produce more heat, and vice versa.
Power transformer – It is an electrical device which is designed to transfer electrical power from one circuit to another without altering the frequency. It functions on the principle of electro-magnetic induction and is essential for transmitting power between generators and primary distribution circuits.
Power transmission – It is the process of moving energy from a source to a location where it is used to perform useful work, which can involve mechanical, electrical, hydraulic, or pneumatic methods. Specifically in electrical engineering, it is the large-scale movement of electricity through a network of high-voltage lines from power plants to substations for distribution to consumers. In mechanical engineering, it involves transferring energy, such as rotational motion or torque, between components using systems like gears, belts, or chains.
Power turbine – It is a rotating mechanical device which converts the kinetic energy from a moving fluid (like water, steam, or air) into rotational mechanical energy to do useful work. This energy is used for different applications, including generating electricity in power plants by driving a generator, driving turbo-blower, and for industrial processes. The core components include a rotor with blades which spin when the fluid flows through them, and its efficiency depends considerably on the blade design.
Power turn conveyor – It is a conveyor system with a curved section which allows materials to change direction, necessitating periodic checks for alignment, belt condition, and overall functionality.
Pozzolana – It is a natural or artificial material containing reactive silica that, when finely divided and in the presence of moisture, chemically reacts with alkalis to form cementing compounds, enhancing the properties of concrete. Examples include volcanic ash, pumice, and fly ash.
Pozzolanic materials – These are defined as naturally available, fine particles of siliceous and aluminous substances which react with calcium hydroxide in the presence of water to form cementitious compounds, improving the quality and durability of concrete by reducing permeability and preventing corrosion.
Practical experimentation – It is the hands-on process of designing, conducting, and analyzing tests or simulations to evaluate designs, materials, and processes, thereby gathering data to understand how different factors influence system behaviour and to inform design improvements. This methodology applies theoretical knowledge to real-world situations to confirm hypotheses, refine existing designs, and develop innovative solutions through a structured approach of observation and controlled manipulation of variables.
ppm – It is the abbreviation for parts per million. It is used in chemical determinations as one part per million parts by weight.
Practice – It is a human activity which involves the introduction of a new source of exposure of people to a hazard or increases an existing exposure. A new practice needs a justification decision.
Prandtl equations – These refer to a simplified form of the Navier-Stokes equations which apply to the boundary layer of fluid flow, allowing for easier analysis of the flow past a surface, such as a flat plate, by neglecting certain small terms when the boundary layer is thin.
Prandtl number (Pr) – It is a dimensionless number which is defined as the ratio of momentum diffusivity to thermal diffusivity.
Praseodymium – It is a chemical element having symbol Pr and the atomic number 59. It is the third member of the lanthanide series and is considered one of the rare-earth metals. It is a soft, silvery, malleable and ductile metal, valued for its magnetic, electrical, chemical, and optical properties. It is too reactive to be found in native form, and pure praseodymium metal slowly develops a green oxide coating when exposed to air.
Pre-adsorption – It is the initial or preliminary adsorption of molecules onto a surface, frequently to condition the surface for subsequent steps or to achieve a specific goal like improving a material’s properties or increasing the effectiveness of a separation process. For example, pre-adsorbing a specific vapour can help measure adsorption energy.
Pre-ageing – It is a thermal treatment after quenching and before the end of the precipitation incubation period.
Pre-alloyed powder – It is a metallic powder composed of two or more elements which are alloyed in the powder manufacturing process and in which the particles are of the same nominal composition
throughout.
Pre-arc period -It is also called pre-spark period. In emission spectroscopy, it is the time interval after the initiation of an arc (or spark) discharge during which the emitted radiation is not recorded for analytical purposes.
Precambrian shield – It is the oldest, most stable regions of the earth’s crust.
Precast concrete – It is a type of concrete which is manufactured in reusable moulds at a controlled, off-site factory, then cured and transported to the construction site for assembly. This technique creates standardized, high-quality concrete elements like beams, slabs, and wall panels which contribute to faster construction, improved structural integrity, and higher design flexibility compared to site-cast concrete.
Pre-cast concrete piles – These piles are produced either in a manufacturing plant or in a casting yard. Reinforcement is provided to resist handling and driving stresses. Pre-cast piles can also be pre-stressed using high strength steel pre-tensioned cables. Square and octagonal piles are cast in horizontal forms, while round piles are cast in vertical forms. After the piles are cast, they are to be cured under damp sand, straw, or mats for the period needed by the specifications, frequently 21 days, if cured under ambient temperatures. With the exception of short lengths, pre-cast concrete piles are to be reinforced with sufficient steel to prevent damage or breakage while they are being handled from the manufacturing plant / casting beds to the driving positions. The piles are required to contain longitudinal reinforcing steel in a quantity not less than 2 % of the volume of the pile. Lateral steel is to be at least 6 millimeters diameter round bars, spaced not more than 300 millimeters apart, except at the top and bottom of a pile, where the spacing is not to exceed 75 millimeters. The concrete cover over the reinforcing steel is to be at least 50 millimeters.
Precast construction – It is the system of manufacturing standardized concrete components in a controlled environment off-site, such as a factory, and then transporting them to the construction site for assembly into the final structure. These prefabricated elements, like wall panels, beams, and columns, are cast in reusable moulds, cured under controlled conditions for high quality, and then assembled on-site using cranes.
Precautionary action – It is a preventative measure taken to mitigate potential harm or risk to human health or the environment, particularly when scientific evidence is incomplete but a potential for severe consequences exists. It follows the precautionary principle, emphasizing a ‘better safe than sorry’ approach by taking action to prevent damage, rather than waiting for conclusive proof of harm. Examples include conducting further monitoring, implementing safety factors, or even halting a project until potential risks are better understood.
Precedence diagram – It is a visual tool from the precedence diagramming method (PDM) which uses nodes (boxes) to represent project activities and arrows to show the logical dependencies between them. This activity-on-node (AON) (or nodal) diagram creates a project network, helping engineers and project managers visualize the project flow, identify critical paths, and schedule tasks more accurately by illustrating four types of dependencies (finish-to-start, start-to-start, finish-to-finish, and start-to-finish).
Precedence diagramming method (PDM) – It is also called activity-on-node (AON) method. It is a visual project scheduling technique which represents project activities as nodes (boxes) and shows their logical interdependencies with arrows. It forms a project schedule network diagram, helping to identify the sequence and critical path of tasks, allowing project managers to understand workflows, overlaps, and critical timelines to make informed decisions for project execution.
Preceramic polymers – These are also known as polymer precursors. These polymers can be converted into ceramics by pyrolysis. They normally contain carbon or silicon.
Precious metals – These are relatively scarce, highly corrosion resistant, valuable metals found in periods 5 and 6 (groups VIII and Ib) of the periodic table. They include ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold.
Precipitant – It is a chemical compound or reagent which causes a chemical reaction resulting in the formation of a solid precipitate when added to a solution.
Precipitant agent – It is a chemical substance added to a solution which reacts with dissolved substances to form an insoluble solid, known as a precipitate. This process, called precipitation, causes the substance to separate from the solution as a solid. Precipitant agents are used to identify, separate, or remove specific contaminants from liquids.
Precipitate – It is a solid substance which separates from a liquid solution or diffuses out of a solid alloy during the process of precipitation. It also means to separate from another substance by forming a distinct, condensed solid phase.
Precipitate-free zone (PFZ) – It is a region adjacent to the grain boundary in which there is no (or little) precipitate, while there is a precipitate present in the grain interior (normally fine) and precipitates in the grain boundary. It is frequently associated with poor corrosion resistance and / or poor fracture toughness. The presence of a precipitate free zone frequently results in fracture in the region.
Precipitation – It is the separation of a new phase from solid or liquid solution, normally with changing conditions of temperature, pressure, or both. It is the process of producing a separable solid phase within a liquid medium, e.g., by transforming the dissolved solute of a supersaturated solution into an insoluble solid, or the diffusion of a distinct solid phase out of a solid alloy. A reagent that causes such a reaction is called the precipitant, and the separable solid itself is the precipitate. More generally, the term can refer to the formation of any new condensed phase by changing the physical properties of a system (e.g., water vapour condensing into liquid water droplets). In metals, it is the separation of a new phase from solid or liquid solution, normally with changing conditions of temperature, pressure, or both. In meteorology, precipitation is any product of the condensation of atmospheric water vapour which falls from clouds because of the gravitational pull. The main forms of precipitation include drizzle, rain, rain and snow mixed, snow, ice pellets, graupel and hail. Precipitation occurs when a portion of the atmosphere becomes saturated with water vapour (reaching 100 % relative humidity), so that the water condenses and ‘precipitates’ or falls.
Precipitation annealing – It is the heating of a quenched and precipitation hardened work-piece for some time at a temperature between the artificial ageing temperature and the solution treatment temperature. It produces considerable softening by coalescing the hardening precipitates.
Precipitation (deposit) etching – It consists of development of microstructure in a metallographic sample through formation of reaction products at the surface of the microsection.
Precipitation hardening – It is the hardening in metals which is caused by the precipitation of a constituent from a super-saturated solid solution.
Precipitation hardening stainless steels – These steels are chromium-nickel stainless steels containing precipitation-hardening elements such as copper, aluminium, or titanium. Precipitation-hardening stainless steels can be either austenitic or martensitic in the annealed condition. Those which are austenitic in the annealed condition are frequently transformable to martensite through conditioning heat treatments, sometimes with a sub-zero treatment. In most cases, these stainless steels attain high strength by precipitation hardening of the martensitic structure.
Precipitation heat treatment – It is artificial aging of metals in which a constituent precipitates from a super-saturated solid solution. It is one of the different aging treatments conducted at high temperatures to improve certain mechanical properties through precipitation from solid solution.
Precipitation process, waste-water – The process of precipitation is carried out in two steps for the removal of the metal compounds from the stream of the waste-water. The mixing of precipitants with the waste-water and allowing a formation of the insoluble metal precipitants is the first step of the precipitation process. The removal of the precipitated metals from the waste-water through clarification and filtration is carried out in the second step and then the resulting sludge is being treated in a proper manner, and after treatment, it is recycled or disposed of. The important parameter to be considered in a chemical precipitation is pH controlling.
Precise measurement – It is one where repeated measurement of the same quantity yield very similar results. It is about the consistency and repeatability of measurements, not their closeness to the true value. For example, if a weighing scale consistently reads 5 kilograms for an object which actually weighs 5 kilograms, the measurements are precise.
Precision – It means how close the results of multiple experimental trials or observations are to each other. In case of instruments, precision is the degree of exactness for which an instrument is designed or intended to perform. It is a measure of consistency or repeatability of measurements, i.e., successive readings do not differ or there is the consistency of the instrument output for a given value of input. A very precise reading is not a perfect accurate reading. Precision is a term which describes an instrument’s degree of freedom from random errors. If a large number of readings are taken of the same quantity by a high precision instrument, then the spread of readings is very small. Precision is frequently, though incorrectly, confused with accuracy. High precision does not imply anything about measurement accuracy. A high precision instrument can have a low accuracy. Low accuracy measurements from a high precision instrument are normally caused by a bias in the measurements, which is removable by recalibration of the instrument. The ISO (International Organization for Standardization) has banned the term precision for describing scientific measuring instruments because of its several confusing everyday connotations.
Precision alignment – It is the accurate adjustment of conveyor components for ensuring proper alignment and efficient material movement, needing regular checks and adjustments.
Precision bearings – These are high-quality bearings which are used in equipment components for improved durability and reduced friction, necessitating regular checks for wear, alignment, and overall bearing condition.
Precision casting – It is a metal casting of reproducible, accurate dimensions, regardless of how it is made. It is frequently used interchangeably with investment casting.
Precision engineering – It is the discipline of designing and manufacturing products and their associated tools and machinery to be highly accurate, with extremely tight tolerances and consistent repeatability. It uses advanced technologies and techniques to achieve this high level of accuracy, enabling the production of components that are consistently correct in size and shape to meet exact specifications, even at the sub-micrometer scale.
Precision forging – It is a forging produced to closer tolerances than normally considered standard by the industry. With precision forging, a net shape, or at least a near-net shape, can be produced in the as-forged condition.
Precision grinding – It is machine grinding to specified dimensions and low tolerances.
Precision instruments – These are devices designed to perform tasks or make measurements with extremely high accuracy and minimal error, frequently used in technical fields where exactness is crucial. These tools have fine scales or digital readouts which allow for the detection of minute changes, ensuring measurements are as accurate and reliable as possible, though they can need careful handling because of their less robust construction. Examples include micrometers, vernier calipers, precision balances, and optical instruments like microscopes.
Precision machining – It is a high-accuracy subtractive manufacturing process which uses advanced computer numerical control (CNC) machinery to remove material from a work-piece, producing components with extremely tight tolerances, complex shapes, and flawless surface finishes to meet exact digital specifications. It is critical for those industries, where parts are required to fit together with extreme accuracy for proper function and safety.
Precision manufacturing – It is the process of creating intricate, high-quality components and products with extreme accuracy and tight tolerances by using advanced technologies, such as computer-aided design (CAD) and computer-aided manufacturing (CAM) systems, along with computer-controlled machinery like CNC machines. This method emphasizes meticulous design, precise fabrication, and a focus on reliability, reducing errors, waste, and lead times to meet the exact specifications needed by modern, high-tech industries.
Precision part – It is also called precision sintered part. It is a powder metallurgy part which is compacted and sintered that is closely conforming to specified dimensions without a need for substantial finishing.
Precision plate sawing – It involves sawing plate (mainly aluminum plate products) into square or rectangular shapes to tolerances as close as 0.08 of a millimeter.
Precious metals – These are rare, naturally occurring metallic chemical elements of high economic value. Precious metals, particularly the noble metals, are more corrosion resistant and less chemically reactive than majority of the elements. They are normally ductile and have a high lustre. Precious metals are now regarded mainly as industrial raw materials.
Precoat – In investment casting, it a special refractory slurry applied to a wax or plastic expendable pattern to form a thin coating that serves as a desirable base for application of the main slurry. It is also to make the thin coating, as well as the thin coating itself.
Precoated metal products – These are mill products which have a metallic, organic, or conversion coating applied to their surfaces before they are fabricated into parts.
Precoated steel sheet – It is sheet which is frequently coated in coil form before fabrication either by the steel mills or by specialists known as coil coaters. This prefinished or precoated sheet is ready for fabrication and use without further surface coating.
Precoating – It consists of coating the base metal in the joint by dipping, electroplating, or other applicable means prior to soldering or brazing.
Pre-combustion capture technologies – These capture technologies involve removing pollutants and carbon di-oxide in the upstream treatment of fossil fuels prior to their combustion for the recovery of heat (through steam), or the production of electric power or hydrogen. A drawback of post-combustion carbon capture is the low carbon di-oxide concentration in the flue gases which leads to a relatively high energy penalty and high cost of carbon capture. Pre-combustion strives to reduce these penalties by decarbonizing the process stream rich in carbon di-oxide before combustion of the remaining hydrogen rich fuel. To achieve decarbonization of hydrocarbon fuels, they are first converted into a syngas through the gasification of a fuel with oxygen (or air). The syngas is a mixture of carbon mono-oxide, hydrogen, carbon di-oxide, and water, depending on the conversion process and the fuel and other components.
Precondition – It is the initial state of the system or its environment necessary for an operation to proceed as expected. It is a requirement which is to be met before an activity or process can occur, such as completing a prerequisite task or event.
Pre-consolidation pressure – It is the vertical stress level at which soil begins to experience irreversible mechanical behaviour, serving as an important parameter for characterizing the response of energy geo-structures and determining the over-consolidation ratio. It can be determined through the analysis of oedometric curves in a semi-logarithmic stress-strain plot.
Pre-cracked sample – It is a mechanical test sample which is notched and subjected to alternating stresses until a crack has developed at the root of the notch.
Precure – It is the full or partial setting of a synthetic resin or adhesive in a joint before the clamping operation is complete or before pressure is applied.
Precursor – For carbon or graphite fibre, the rayon, poly-acrylo-nitrile, or pitch fibres from which carbon and graphite fibres are derived.
Predictable process – It is one with minimal variability, allowing for consistent and reliable outcomes. This is achieved by minimizing differences caused by provider variations and stabilizing a process so its future performance can be accurately anticipated from its past performance. The ability to predict future performance enables engineers to set realistic goals, optimize resource allocation, and meet customer expectations.
Predictability – It is the extent to which future states of a system can be predicted based on knowledge of current and past states of the system.
Predicted cost – It is also known as projected cost or anticipated cost. It is an estimated total expenditure needed to complete a project or process, based on available data, project scope, and future expectations. It is a forward-looking calculation used for financial planning, risk management, and decision-making, taking into account resources like labour, materials, equipment, and overhead, and is refined as the project progresses.
Prediction error – It is the quantifiable difference between a model’s forecasted outcome and the actual observed value, serving as a measure of the model’s accuracy and reliability. It quantifies the failure of a predictive model to accurately forecast results and is a crucial parameter in different fields, including statistical analysis, artificial intelligence, and system identification, to assess model performance and make informed decisions.
Prediction interval – A prediction interval is a calculated range of values known to contain some future observation over the average of repeated trials with specific certainty (probability). The correct interpretation of a prediction interval is that if the analyst is to repeatedly draw samples at the same levels of the independent variables and compute the test statistic (mean, regression slope, etc.), then a future observation lies in the (1-alpha) % prediction interval a times out of 100. The prediction interval differs from the confidence interval in that the confidence interval provides certainty bounds around a mean, whereas the prediction interval provides certainty bounds around an observation.
Predictive analysis – Predictive analysis utilizes historical and present facts to reach future predictions. It can also use data from a subject to predict the values of another subject. There are different predictive models. However, a simple model with more data can work better in general. Hence, the prediction data set and also the determination of the measuring variables are important aspects to consider.
Predictive assessment – It is a process which leverages historical and real-time data, artificial intelligence, and statistical modeling to forecast future behaviours and outcomes, aiming to prevent problems and optimize performance. This approach enables engineers to predict issues like equipment failures or potential product defects, allowing for proactive, data-driven decisions rather than reactive responses to failures.
Predictive intelligence – It is the use of data, algorithms, and machine learning techniques to analyze patterns and make predictions about future events or behaviours. It is a powerful analytical approach, leverages historical and real-time data to forecast future outcomes, enabling organizational management to make informed decisions.
Predictive maintenance – It is defined as measurements which detect the onset of a degradation mechanism, thereby allowing casual stressors to be eliminated or controlled prior to any significant deterioration in the component / equipment physical state. Predictive maintenance is a set of activities which detect changes in the physical condition of equipment (signs of failure) in order to carry out the appropriate maintenance work for maximizing the service life of equipment without increasing the risk of failure. It is classified into two kinds according to the methods of detecting the signs of failure namely (i) condition-based predictive maintenance, and (ii) statistical-based predictive maintenance. Main predictive maintenance technologies are thermography, oil or lubricant analysis, ultrasonic or ultrasound analysis, vibration analysis, motor analysis, and performance trending etc.
Predictive nomogram – It is a mathematical formula, based on statistical modelling, which facilitates forecasting patient outcomes. In survival analysis, the predicted outcome is typically the probability of surviving a given length of time before experiencing the study end point.
Pre-drying – It is a process of reducing the moisture content of coal before it is used in power generation or other industrial applications. This is done to improve the coal’s heating value, reduce transportation costs, and improve the efficiency of combustion and gasification processes. Pre-drying involves removing moisture from coal, typically through heating, to lower its moisture content. This can be achieved through different methods, including using waste heat from other processes or dedicated drying equipment.
Pre-engineered building (PEB) – It is a steel structure which is designed, engineered, and fabricated off-site in a factory as per the specific project requirements before being transported and assembled at the construction site. This method allows for optimized design, cost-efficiency, faster construction, reduced waste, and high-quality, precise components manufactured in a controlled environment using computer-aided design (CAD) / computer-aided manufacturing (CAM) technologies. Pre-engineered buildings are customizable and adaptable for various applications, including industrial, commercial, and institutional buildings.
Prefabricated building – It is a building which is manufactured and constructed using prefabrication. It consists of factory-made components or units which are transported and assembled on-site to form the complete building. Different materials are combined to create a part of the installation process. It is also known as pre-engineering building.
Prefabricated construction – It is a method of building where components like walls, floors, and roofs are manufactured and assembled off-site in a factory setting and then transported to the construction site for final assembly into a complete structure. This approach streamlines the building process, leading to increased productivity, improved quality control because of factory precision, reduced on-site labour, minimized waste, and accelerated project timelines compared to traditional construction methods.
Pre-feasibility mineral resource – Pre-feasibility mineral resource is that part of an indicated and in some circumstances measured mineral resource which has been shown by pre-feasibility study as not economically mineable or can become economically viable subject to changes in technological, economic, environmental and / or other relevant conditions.
Preferential oxidation – It is a catalytic process which selectively oxidizes a specific chemical, typically carbon mono-oxide (CO), to a less harmful compound, such as carbon di-oxide (CO2), within a mixture of gases. The main application is the removal of trace carbon mono-oxide from hydrogen-rich streams used as fuel in proton exchange membrane (PEM) fuel cells, as even low levels of carbon mono-oxide can poison the platinum anode. This process operates at relatively low temperatures (80 deg C to 200 deg C) and needs a highly selective catalyst to avoid the side reaction of hydrogen (H2) oxidation.
Preferred orientation – It is a condition of a polycrystalline aggregate in which the crystal axes are not randomly distributed with respect to the component geometry, but rather show a tendency for alignment of a specific direction(s) of the crystal parallel to a coordinate axis of the bulk material. Some textures are axisymmetric (fibre textures), in which a single direction in a grain is aligned with the principal working direction. In other cases, two directions of the grain are aligned with directions of the bulk body after working (rolling or deformation textures) and textures in rolled sheet after annealing (annealing textures).
Preferred stock level – It refers to the optimum quantity of stock which is to be maintained for an item, balancing the need to fulfill orders and production demands without incurring the costs of excessive overstocking or the negative impacts of stockouts. This is an inventory management strategy to ensure timely delivery and efficient use of capital by determining ideal stock quantities based on demand, lead times, and safety stock requirements.
Pre-filtration – It is a preliminary filtration step which removes large contaminants from a fluid or air stream to protect and extend the life of downstream, more sensitive, and frequently more costly filters or membranes. It acts as a first line of defense, reducing the overall load on subsequent filtration stages by capturing coarse particles, preventing issues like clogging, damage, increased pressure drops, and more frequent cleaning.
Pre-finishing block – Pre-finishing block is configured to produce the needed process feed sections to the no-twist block to support the maximum product finishing speed. All process sections are rolled in the pre-finishing block utilizing an oval-round pass design sequence to minimize the investment in rolls, reduce operating cost and enable high productivity, and high quality of the process sections. The pre-finishing block stands are used to produce the sections needed for the no-twist block. The pre-finishing block utilizes 230 millimeters cantilever roll housings to provide the needed separating force capacity and roll strength needed for the process. Carbide rolls are used for increased pass life, thereby reducing downtime and increasing mill efficiency. The carbide rolls also provide superior surface quality over the life of the groove, further improving the quality of the finished product.
Prefit – It is a process for checking the fit of mating detail parts in an assembly prior to adhesive bonding, for ensuring proper bond lines. Mechanically fastened structures are sometimes prefitted to establish shimming requirements.
Pre-flux – It is the process of fluxing steel before it enters the galvanizing pot as opposed to using a top flux layer, which is located on top of the molten zinc in the pot.
Preform – It consists of brazing or soldering filler metal fabricated in a shape or form for a specific application. It is a pre-shaped fibrous reinforcement formed by distribution of chopped fibres or cloth by air, water flotation, or vacuum over the surface of a perforated screen to the approximate contour and thickness desired in the finished part. It is a pre-shaped fibrous reinforcement of mat or cloth formed to the desired shape on a mandrel or mock-up before being placed in a mould press.
Preform binder – It is a resin applied to the chopped strands of a preform, normally during its formation, and cured so that the preform retains its shape and can be handled.
Preformed ceramic core – It is a preformed refractory aggregate inserted in a wax or plastic pattern to shape the interior of that part of a casting which cannot be shaped by the pattern. The wax is sometimes injected around the preformed core.
Preformed shape – It is the shape made from an unshaped refractory, cast or moulded and pre-treated by the manufacturer, so that it can be directly placed in service.
Pre-formed shape (rigid) – It is the rigid shape made of ceramic fibre with the addition of inorganic and / or organic binder, fired or unfired.
Preforming – It is the initial pressing of a metal powder to form a compact which is to be subjected to a subsequent pressing operation other than coining or sizing. It is also preliminary forming operations, especially for impression-die forging.
Pre-forming tool – It is a type of shaping tool used in manufacturing that brings a material, such as metal or plastic, to a preliminary shape or size before a final shaping operation, a process also known as ‘preforming’. These tools can be specific cutting tools, punches and dies, or other devices with a unique contour designed to reproduce a desired form on a workpiece without removing material but rather deforming it.
Pregel – It is an unintentional, extra layer of cured resin on part of the surface of a reinforced plastic. It is not related to gel coat.
Preheat – It is a non-standard term for preheat temperature.
Preheat current (resistance welding) – It is an impulse or series of impulses which occur prior to and are separated from the welding current.
Preheated air – It is the air at a temperature exceeding that of the ambient air.
Preheating – It is the heating before some further thermal or mechanical treatment. It is the heating of a compound before moulding or casting, to facilitate the operation or reduce the moulding cycle. For tool steel, it is heating to an intermediate temperature immediately before final austenitizing. For some non-ferrous alloys, it is the heating to a high temperature for a long time, in order to homogenize the structure before working. In welding and related processes, it is the heating to an intermediate temperature for a short time immediately before welding, brazing, soldering, cutting, or thermal spraying. In powder metallurgy, it is an early stage in the sintering procedure when, in a continuous furnace, lubricant or binder burn off occurs without atmosphere protection prior to actual sintering in the protective atmosphere of the high heat chamber.
Preheating furnace – It is a furnace which gradually raises the temperature of raw materials or work-pieces to a specific point before they undergo further processing, such as welding, casting, or heat treatment. The main goals of preheating are to improve the material’s workability, minimize thermal stress and distortion, improve metallurgical properties, and increase the overall energy efficiency and productivity of the subsequent process.
Preheating systems of scrap – A number of scrap preheating systems utilizing the heat associated with off gases have been developed, some based on batch bucket systems and others on continuous shaft systems. With single shaft system up to 77 kilowatts hour per ton of steel of electric energy can be saved. Finger shaft system allows savings up to 110 kilowatts hour per ton of steel, which is around 25 % of the electricity input.
Preheat temperature – It is a specified temperature which the base metal is required to attain in the welding, brazing, soldering, thermal spraying, or cutting area immediately before these operations are performed.
Preimpregnation – In case of reinforced plastics, it is the practice of mixing resin and reinforcement and effecting partial cure before use or shipment to the user.
Preliminary design review – It is a formal, project-level assessment which confirms the preliminary design of a system or product is technically sound, meets requirements, and is ready to proceed to detailed design. It is a critical checkpoint where stakeholders evaluate the functional architecture, design specifications, risk assessment, cost, and schedule, ensuring the selected design approach is feasible and well-defined before committing resources to detailed design.
Preliminary Feasibility study – A Preliminary Feasibility study (Pre-Feasibility study) is a comprehensive study of a range of options for the technical and economic viability of a mineral project which has advanced to a stage where a preferred mining method, in the case of underground mining, or the pit configuration, in the case of an open pit, is established and an effective method of mineral processing is determined. It includes a financial analysis based on reasonable assumptions on the Modifying factors and the evaluation of any other relevant factors which are sufficient for a Competent person, acting reasonably, to determine if all or part of the Mineral resources can be converted to an Ore reserve at the time of reporting. A Pre- Feasibility study is at a lower confidence level than a Feasibility study.
Preliminary hazard analysis (PHA) – It involves a high-level, initial safety assessment during the early stages of a project or system design to identify potential hazards, assess their severity and likelihood, and establish initial requirements for controls and further risk analysis. The goal is to proactively integrate safety into the design, prevent accidents, ensure regulatory compliance, and form a foundation for more detailed safety analyses later in the system’s lifecycle.
Preliminary investigation – It is the initial fact-finding stage of the investigative process in the case of an accident or an equipment failure. It involves attending to injured persons, physical detailed observation of the area, collection of samples and taking relevant photographs of failure part, finding out potential reasons, questioning witnesses, preserving the scene of accident or failure, forwarding information to relevant authorities, and preparing a preliminary report for follow-up investigators.
Preliminary waste-water treatment – The objective of preliminary treatment is the removal of materials which can cause blockages, clogging of downstream equipment and equipment abrasion. Preliminary treatment is normally carried out before the waste-water is sent to the effluent treatment plant (ETP) and for improving the performance of the effluent treatment plant. In this treatment, the coarse solids and other large materials from the waste-water are removed. The removal of these materials is essential for enhancing the operational and maintenance efficiency of the subsequent treatment units. In this treatment of waste-water, a number of unit processes are used to eliminate the undesirable characteristics of waste-water. These normally include (i) control of the odour, and (ii) such operations as pre-aeration, coarse solid grinding, and removal of large materials using screens and grates etc. Many a times the removal of oil and grease as well as pH correction is also carried out.
Premix – It is a uniform mixture of components prepared by a powder producer for direct use in compacting. It is also a term which is sometimes applied to the preparation of a premix.
Premix burner – It is a type of industrial burner where fuel and air are combined before they reach the combustion zone. This contrasts with nozzle-mix burners, where fuel and air are mixed during combustion. The premixing process in these burners allows for more efficient and cleaner combustion, frequently resulting in lower emissions, particularly of oxides of nitrogen (NOx) and carbon mono-oxide. It is also a burner which is used in flame emission and atomic absorption spectroscopy in which the fuel gas is mixed with the oxidizing gas before reaching the combustion zone.
Premixed combustion – n this method, fuel and air are mixed before the burner head. A chemical reaction occurs between fuel and air at the flame formation place. This technology is used in premixed burners.
Pre-moulding – It is the lay-up and partial cure at an intermediate cure temperature of a laminated or chopped-fibre detail part to stabilize its configuration for handling and assembly with other parts for final cure.
Pre-painted galvanized steel (PPGI) – It is a type of steel coil or sheet which is coated with a layer of zinc (galvanized) and then further coated with one or more layers of paint or other protective coatings before being formed into different products. This combination provides excellent corrosion resistance from the zinc layer and improved aesthetics and durability from the paint coating.
Pre-painted steel sheets – These sheets are produced by forming polymer films 10 micrometers to 30 micrometers thick on the surfaces of galvanized steel sheets in order to provide specific colours and designs. They are mainly used in applications such as roofing, siding, and shutters on various buildings. On the other hand, organic composite coated steel sheets are produced by forming thin organic composite films 1 micrometer to 2 micrometers thick on the surfaces of galvanized steel sheets. They are used in applications which do not need such aesthetic designs as pre-painted steel sheets, e.g., roofing, siding, and structural materials of non-residential, industrial and commercial buildings. Basic properties required of organic composite coated steel sheets are formability (the property which suppresses the peeling and scoring of metal coatings during roll forming) and corrosion resistance. In addition to these properties, pre-painted steel sheets have to have an excellent surface appearance, free from cracks and other damage. This has to be maintained even after forming.
Preparation phase – It involves the preliminary activities and planning undertaken before the main execution of a project or task, focusing on gathering information, defining scope, assembling resources, and establishing the necessary conditions for success. It ensures a solid foundation is built, encompassing aspects like requirements analysis, stakeholder alignment, project planning, and resource allocation to ensure the project can proceed efficiently and effectively.
Preply – It is a composite material lamina in the raw-material stage, ready to be fabricated into a finished laminate. The lamina is normally combined with other raw laminae before fabrication. A preply includes a fibre system which is placed in position relative to all or part of the needed matrix material to constitute the finished lamina. An organic matrix preply is called a prepreg. Metal-matrix preplies include green tape, flame-sprayed tape, and consolidated mono-layers.
Prepolymer – It is a chemical intermediate whose molecular weight is between that of the monomer or monomers and the final polymer or resin.
Prepreg – · In composites fabrication, either ready-to-mould material in sheet form or ready-to-wind material in roving form, which can be cloth, mat, unidirectional fibre, or paper, impregnated with resin and stored for use. The resin is partially cured to a B-stage and supplied to the fabricator, who lays up the finished shape and completes the cure with heat and pressure. The two distinct types of prepreg available are commercial prepregs, in which the roving is coated with a hot melt or solvent system to produce a specific product to meet specific customer requirements; and wet prepreg, in which the basic resin is installed without solvents or preservatives but has limited room-temperature shelf life.
Prepreg process – It refers to the manufacturing technique involving the use of pre-impregnated composite materials. A prepreg is a composite material consisting of reinforcing fibres (like carbon or glass) pre-impregnated with a resin system, which is typically partially cured to allow for handling and subsequent full curing under heat and pressure. The prepreg process involves manufacturing and using these materials to create high-performance parts with consistent, high-quality fibre-to-resin ratios.
Pre-reactor – It is used in hydro-refining of crude benzol. The vapours from the top of the evaporator at the temperature of 180 deg C are heated in a heat exchanger to the temperature range of 190 deg C to 225 deg C by passing main reactor effluent through shell side. The reactor is provided with a bed of catalyst. The most commonly used catalyst is the nickel-molybdenum catalyst. In this pre-reactor such as di-olefins, styrene and carbon di-sulphide are removed by hydrogenation. Feed enters from the bottom of the reactors through the catalyst bed. The temperature at the feed at the inlet of the reactor is ranging from 190 deg C to 225 deg C. The life cycle of the catalyst is sensitive to the temperature. Because of the exothermic reaction, the outlet temperatures are in the temperature range of 200 deg C to 235 deg C. Due to continuous operation of the catalyst bed, coke like polymerization products deposit on the catalyst bed resulting in the lower efficiency. This can be overcome by increasing the inlet temperature of the reactor. Catalyst activity can be determined by the temperature difference between inlet and outlet, which is required to be more than 10 deg C. The catalyst can be regenerated by heating the bed with steam and air.
Pre-reduction – It is the partial reduction of an ore’s oxides (like iron or manganese) outside of its primary melting furnace, typically using a rotary kiln or similar technology. This initial reduction step removes some oxygen, making subsequent processes in the main furnace more efficient, reducing energy consumption, and allowing for better control over the final product.
Prescribed accuracy – It refers to the specified or needed level of truthfulness and correctness a measurement or system is required to achieve to be considered acceptable for a given application, project, or process. It goes beyond simply a number, defining the acceptable deviation from a true value and frequently incorporating precision as well, to ensure the engineering design or manufacturing process meets its intended goals and standards.
Prescribed boundary condition – It is a specific constraint or value set on the boundary of a computational domain to model how a system or material behaves. These are used in simulations to define fixed points, displacements, pressures, forces, temperatures, or other properties which influence the solution within the domain, helping to close the mathematical problem and accurately represent real-world scenarios.
Prescribed performance – It refers to a defined function which describes the transient performance of a system, characterized by design parameters, and includes constraints on tracking errors within specified upper and lower bounds.
Prescriptive maintenance – It is an advanced maintenance strategy which utilizes artificial intelligence (AI) to not only predict equipment failures but also to recommend specific, actionable steps to prevent them. It goes beyond predictive maintenance, which only identifies potential problems, by offering solutions and optimizing asset performance. This proactive approach aims to minimize downtime, reduce maintenance costs, and enhance overall operational efficiency. In case of conveyor belts, it is a higher level than preventive maintenance. It additionally informs what actions to take. Very advanced radiographic monitoring systems are able to provide this for steel-cord conveyor belts.
Prescriptive standard – It is a standard which states the requirements in terms of specific details and leaves no discretion to the designer. It is sometimes referred to as a design standard.
Pre-shadowed replica – It is a replica for fractographic or metallographic inspection which is formed by the application of shadowing material to the surface to be replicated. It is formed before the thin replica film is cast or otherwise deposited on the surface.
Pre-sintered blank – It is a compact sintered at a low temperature but at a long enough time to mae it sufficiently strong for metal working.
Pre-sintered density – It is the relative density of a pre-sintered compact.
Pre-sintering – It is the heating a powder metallurgy compact to a temperature below the final sintering temperature, normally to increase the ease of handling or shaping of a compact or to remove a lubricant or binder (burn off) prior to sintering.
Press – It is a machine tool having a stationary bed and a slide or ram which has reciprocating motion at right angles to the bed surface, the slide being guided in the frame of the machine. It is the machine used for compacting, sizing, or coining. Presses can be (i) mechanical e.g., eccentric, crank, cam, toggle, knuckle joint, and rotary table, (ii) hydraulic e.g., single action, double action, and multiple action, or (iii) combination mechanical-hydraulic. The term also denotes the process of producing a compact, which is also sometimes called pressing.
Press brake – It is an open-frame single-action press used to bend, blank, corrugate, curl, notch, perforate, pierce, or punch sheet metal or plate. Press brake is mainly designed for the precise bending and forming of thin plate sheets. With the development of technology, from the mechanical press brake to the emergence of the electric press brake, and then to the introduction of computer numerical control technology, the function and efficiency of the press brake have significantly improved. It can bend the sheet into different angles and improve processing accuracy and production efficiency through computer numerical control. Press brakes are ordinarily used for small lots, non-critical work, and long parts.
Press-brake forming – It is a metal forming process in which the work-piece is placed over an open die and pressed down into the die by a punch which is actuated by the ram portion of a press brake. The process is most widely used for the forming of relatively long, narrow parts which are not adaptable to press forming and for applications in which production quantities are very small to warrant the tooling cost for contour roll forming.
Press brake tooling – It refers to the set of specialized tools and dies used in a press brake machine to bend sheet metal into desired shapes and profiles. These tools, consisting of punches and dies, work together to apply force and create precise bends. The selection of appropriate tooling is crucial for achieving desired accuracy, efficiency, and extending the lifespan of both the tooling and the machine itself.
Press capacity – It is the rated force a press is designed to exert at a predetermined distance above the bottom of the stroke of the slide.
Press clave – It is a simulated autoclave made by using the platens of a press to seal the ends of an open chamber, providing both the force needed to prevent loss of the pressurizing medium and the heat needed to cure the laminate inside.
Pressed bar – It is a compact in the form of a bar. It is a green compact.
Pressed density – It is the weight per unit volume of an unsintered compact.
Pressed silicon nitride – It refers to a dense form of the advanced ceramic silicon nitride (Si3N4), produced by sintering silicon nitride powder compacts under high pressure and temperature, frequently with densification additives, to create parts with exceptional strength, fracture toughness, and thermal shock resistance for demanding applications. This high-performance ceramic material is used in extreme mechanical and thermal environments where metals fail
Pressed steel – It refers to steel parts formed by shaping sheets or plates of steel between dies under high pressure, either through a hot or cold process, to achieve a desired form. This method produces items like frames, channels, and gratings, often resulting in lighter, more cost-effective components than those made by hot rolling, and is used extensively in the automotive and construction industries for parts requiring resilience under stress.
Press fit – It is also known as an interference fit or force fit. It is a mechanical assembly method where two parts are joined by forcing a slightly larger part into a slightly smaller hole or receiving component. This process needs substantial applied pressure and creates a strong, secure connection held together by friction and residual stresses (tensile in the hole, compressive in the part) without the need for fasteners like screws or adhesives.
Press forging – In press forging, the metal is shaped not by means of a series of blows as in hammer forging, but by means of a single continuous squeezing action.
Press forming – It is a sheet metal forming operation which is performed with tooling by means of a mechanical or hydraulic press. It is a metal-working process in which the work-piece takes the shape imposed by the punch and die. The applied forces can be tensile, compressive, bending, shearing, or different combinations of these. In some applications, the metal needs appreciable stretching in order to retain the shape of the formed part.
Press-hardened steels (PHS) -These steels are also known as hot-stamped or hot-formed steels. These steels are a type of advanced high-strength steel (AHSS) used in automotive manufacturing to create strong, lightweight components. They are characterized by a high tensile strength (1,500 megapascals to 2,000 mega pascals) achieved through a hot stamping process, which combines heating, forming, and quenching.
Pressing – The preferred term is compacting. It is the process of producing a compact.
Pressing area – It is the clear distance (left to right) between housings, stops, gibs, gib-ways, or shoulders of strain rods, multiplied by the total distance from front to back on the bed of a metal forming press.
Pressing crack – It is a rupture in a green powder metallurgy compact which develops during ejection of the compact from the die. It is sometimes referred to as a slip crack.
Pressing skin – It is the surface of a compact which is superficially more deformed than the interior because of a preferential alignment of the particles caused by contact with the die wall and punch faces.
Pressing tool – It is also called press tool. It is the complete tool assembly consisting of the die, a die adaptor, the punches, and when needed a core rod.
Press length – It is the length of a conveyor belt which can be cured at one time.
Press load – It is the quantity of force which is exerted in a given forging or forming operation.
Press quenching -It is a quench in which hot dies are pressed and aligned with a part before the quenching process begins. Then the part is placed in contact with a quenching medium in a controlled manner. This process avoids part distortion.
Press slide – It is the main reciprocating member of a press, guided in the press frame, to which the punch or upper die is fastened. It is sometimes called the ram. The inner slide of a double-action press is called the plunger or punch-holder slide. 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.
Pressure – It is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure is the pressure relative to the ambient pressure. Different units are used to express pressure. Some of these derive from a unit of force divided by a unit of area. The SI (International System of Units) unit of pressure, the pascal (Pa), e.g., is one newton per square metre.
Pressure altitude – Given an atmospheric pressure measurement, the pressure altitude is the imputed altitude that the International Standard Atmosphere (ISA) model predicts to have the same pressure as the observed value. The National Oceanic and Atmospheric Administration (NOAA) published a formula for directly converting atmospheric pressure in millibars to pressure altitude in feet. The formula is ‘h = 145366.45 [1 – (station pressure in millibars)/1013.25) to the power 0.190284]’.
Pressure atomization – It is a hydraulic process where high-pressure liquid is forced through a small nozzle orifice, converting the liquid’s potential energy into kinetic energy and creating a fine spray of droplets. This pressure generates internal or external forces, like the friction of the fluid against the nozzle or aerodynamic waves, which overcome the surface tension of the liquid, causing it to break apart into smaller, finer particles. The resulting droplet size is influenced by the atomization pressure, with higher pressures leading to smaller, more uniform particles.
Pressure bag moulding – It is a process for moulding reinforced plastics in which a tailored, flexible bag is placed over the contact layup on the mould, sealed, and clamped in place. Fluid pressure, normally provided by compressed air or water, is placed against the bag, and the part is cured.
Pressure balance – It is a device which measures pressure by directly applying the physical principle of ‘pressure = force / area’. It works by having a mass create a downward force, which is opposed by the upward force from the pressure being measured acting on the area of a floating piston. When these forces are equal, the piston floats, and the pressure can be calculated with high accuracy, making them primary reference standards for pressure calibration.
Pressure bonding – It means joining at high temperature of powder metallurgy parts or sections to one another or to wrought metal, sheet, or castings, without using liquid auxiliary metal, such as solder, brazing alloy, or weld metal.
Pressure build-up – It is the increase in force within a confined space, occurring when fluid or gas flow is restricted, causing an accumulation of pressure. It can refer to a literal, physical rise in pressure, such as in a gas tank, or a metaphorical increase in stress or tension in a situation. The term implies a gradual increase in pressure over time.
Pressure casting – It consists of making castings with pressure on the molten or plastic metal, as in die casting, centrifugal casting, cold chamber pressure casting, and squeeze casting. It is also a casting made with pressure applied to the molten or plastic metal.
Pressure class – It is a standardized, non-dimensional number assigned to industrial components like flanges and valves to indicate their maximum operating pressure and temperature rating. These classes define a working range, not a direct pressure, and the allowable pressure decreases as the fluid’s temperature increases. Pressure class is a critical factor in system safety and longevity, with different standards providing classifications based on material, design, and intended use.
Pressure compressor – it is a machine or mechanical device which increases the pressure of a gas by reducing its volume. It draws gas into a chamber, decreases the gas’s volume, and then expels it at a higher pressure, storing the energy as potential energy in the compressed gas. These devices are necessary in several applications, from refrigeration and industrial machinery to gas pipelines and pneumatic systems.
Pressure-controlled welding – It is a resistance welding process variation in which a number of spot or projection welds are made with several electrodes functioning progressively under the control of a pressure-sequencing device.
Pressure controller – It is a device to regulate and control the pressure of fluids or gases within a system. Its primary function is to maintain pressure levels within specified limits, ensuring optimal operation of the system.
Pressure control valve – It is a mechanical device designed to manage and maintain desired pressure levels within a system. The pressure control valve enables the regulation of system pressure to adjust the force on a hydraulic piston rod or the torque on a hydraulic motor shaft. Pressure-control valves are found in practically every pneumatic and hydraulic system. They help in a variety of functions, from keeping system pressures below a desired limit to maintaining a set pressure level in part of a circuit. Different types of pressure control valves include relief, reducing, sequence, counterbalance, safety, and unloading. All of them are typically closed valves, except for reducing valves, which are normally open.
Pressure conveying system – It is a pneumatic conveying method which uses air or gas pressure to transport dry bulk materials like powders, granules, and pellets through enclosed pipelines from a source to a destination. A positive displacement blower at the start of the system generates the airflow and pressure, effectively pushing the material along the pipeline. These systems are effective for moving materials over long distances and can handle high throughputs, frequently from a single source to multiple destinations, such as filling silos.
Pressure cracks – These cracks are caused by fatigue cracks. These are the cracks which form in a material because of repeated or fluctuating stresses below the material’s yield strength, leading to failure. These cracks typically initiate at stress concentrations or existing flaws and grow with each cycle of stress, eventually leading to a larger crack that can cause structural failure.
Pressure cracks and ribbon fatigue spalls – In this case, initially, one or more pressure cracks is formed in an area of local overload, at or near to the barrel surface. Such a crack is normally oriented parallel to the roll axis but propagates in a non-radial direction. In the next stage, a fatigue, cat’s tongue like fracture band propagates progressively in a circumferential direction running more or less parallel to the barrel surface. The direction of propagation is opposite to the direction of roll rotation. Propagation develops within the working surface of the roll, gradually increasing in depth and width followed by a large surface spall of the overlying barrel surface. High local loads at leading edges, cobbles or doubling of the end of the material being rolled, exceed the shear strength of the shell material and initiate the crack. Subsequent to rolling fatigues, the material and the crack propagate until a massive spontaneous spall occurs.
Pressure cylinder – It is a vessel or component designed to safely hold and contain a fluid, such as a gas, liquid, or even a supercritical fluid, under pressure higher than atmospheric pressure. These specialized containers are critical for the storage, transport, and application of pressurized substances, found in common forms like gas cylinders or more complex industrial equipment.
Pressure die – It is a reusable steel mould, or die, into which molten metal is injected at high velocity and pressure to create a cast component. The intense pressure forces the metal to rapidly fill the die’s intricate cavity, resulting in high-volume production of parts with excellent dimensional accuracy and a smooth surface finish. After solidification, the die is opened and the finished part is ejected.
Pressure die casting – It is a manufacturing process where molten metal is injected under high pressure into a steel mould cavity to create complex, high-precision metal parts. This method allows for rapid solidification and the production of components with tight tolerances and excellent dimensional accuracy.
Pressure difference – It is the difference between the pressure on the inlet side of the leak and the pressure on the exit side of the leak.
Pressure distillation – It is consists of distillation under reduced pressure. It is used to purify a liquid which has a tendency to decompose when heated to a high temperature. Under the conditions of reduced pressure, the liquid boils at a temperature lower than its boiling point, and as a result, the liquids do not degrade as they do otherwise.
Pressure-drag – It is also called form drag. It, is a resistive force an object experiences when moving through a fluid (liquid or gas) because of the difference in pressure between its front and rear surfaces. It happens when the fluid flow separates from the object’s body, creating a high-pressure zone at the front and a low-pressure zone (wake) at the back, resulting in a net force opposing the object’s motion.
Pressure-driven process – It is a mass transport method which uses pressure differences as the driving force to separate components in a fluid, very frequently through membranes. By applying pressure to a feed stream across a semipermeable membrane, specific substances are forced through, while others are retained, allowing for purification in fields like water treatment, chemical processing.
Pressure-drop – It is the difference in pressure between two points in a system, caused by resistance to flow.
Pressure dye test – It is a form of leak test in which the systems are filled with liquid, fluorescent oil which is then pressurized for the purpose of driving liquid through possible leakage paths and so make its presence visible when the excess liquid has been removed from the exterior. It is also a leak test in which the systems are immersed in a liquid dye or fluorescent oil and then pressurized for the purpose of driving liquid through possible leakage paths and so make its presence visible when the excess liquid has been removed from the exterior.
Pressure energy – It is also known as flow energy or pressure work. It is the work done to force a unit volume of fluid into a specific space against the prevailing pressure. It is a form of stored or potential energy within a fluid system resulting from the pressure applied to it, enabling it to do work, such as pushing it through a pipe or expelling it from a container.
Pressure equipment – It is any apparatus designed to hold, contain, or transport gases or liquids under pressure, including vessels, piping, boilers, safety accessories, and connected components like flanges. These systems are inherently dangerous because of potential hazards like explosions or leaks, so they are subject to strict regulations and standards for safe design, manufacturing, operation, and monitoring throughout their lifecycle.
Pressure evacuation test – It is a leak test in which one or more devices are placed under gas pressure for a period of time, the objective being to accumulate enough gas in those devices which can leak to permit an indication on a leak detector sensitive to the gas when the devices are placed in an evacuated system jointed to the leak detector. It is also known as ‘inside out method’, back pressuring testing, or bomb test.
Pressure filtration – It is a liquid-solid or liquid-gas separation process which uses applied pressure to force a fluid through a porous filter medium, allowing for higher filtration rates and higher efficiency than gravity filtration. This technique is used in different industries, from water treatment and chemical process, to remove suspended solids and other contaminants from liquids or gases.
Pressure fluctuation – It is a continuous, dynamic change in pressure levels, differing from a constant or static pressure. This variability can stem from various factors, including turbulent flow, or systemic issues in machinery. Fluctuations are frequently indicative of potential problems, or reduced system performance.
Pressure force – It is not a separate force, but rather describes the force which is applied perpendicularly to a surface, divided by the unit area over which it is distributed. In simple terms, it is the quantity of ‘push’ acting on a specific area. The relationship is expressed by the formula ‘pressure (P) = force (F) / area (A)’.
Pressure gas welding (PGW) – It is an oxy-fuel gas welding process which produces coalescence simultaneously over the entire area of abutting surfaces by heating them with gas flames got from combustion of a fuel gas with oxygen and by application of pressure, without the use of filler metal.
Pressure gauge – It is an instrument which measures and indicates the pressure of a fluid (liquid or gas) within a system, displaying it on a calibrated scale. These instruments are necessary for monitoring systems like pneumatic or hydraulic machinery, ensuring safety, product consistency, and proper operation. Pressure gauges work by using a flexible element, such as a Bourdon tube, which deforms under pressure, moving a pointer across a dial to show the reading.
Pressure head – It is the height of a column of fluid which exerts a pressure equivalent to the fluid’s static pressure. It represents the pressure energy of a fluid and is expressed in units of length, such as meters. In short, it quantifies the potential energy in a fluid because of its pressure, by relating the pressure to the height of a hypothetical water column which creates the same pressure.
Pressure-impregnation-carbonization (PIC) – It is a densification process for carbon-carbon composites involving pitch impregnation and carbonization under high temperature and isostatic pressure conditions. This process is carried out in hot isostatic press (HIP) equipment.
Pressure intensifier – It is a layer of flexible material (normally a high-temperature rubber) which is used to ensure the application of sufficient pressure to a location, such as a radius, in a lay-up being cured.
Pressure-less sintering – It means sintering of loose powder.
Pressure level – It is a physical measurement which indicates the force exerted per unit area. While the term ‘pressure level’ can refer to the general concept of pressure, it very frequently denotes a sound pressure level (SPL), which is the measurement of the pressure variation caused by a sound wave relative to a defined reference pressure. SPL is expressed in decibels (dB).
Pressure line – It is a general term for a component or a concept where pressure is the key factor. It can refer to the discharge line in an air-conditioning system, or a fluid-carrying tube in a vehicle’s brake or power steering system. In structural engineering, a pressure line (also called a thrust line or C-line) is the path of the resultant compressive force within a prestressed concrete beam, which is different from the actual cable line.
Pressure load – It is a force exerted perpendicularly to a surface or object, such as wind on a wall or water pressure on a dam. It is a type of static load, where the direction of the force is normal to the face or area it acts upon. Pressure loads are important in engineering to ensure structural stability, as they are a key factor in calculating stresses and deformations within a structure.
Pressure loss – It is also called pressure drop. It is the reduction in a fluid’s total pressure as it moves through a system, caused by frictional forces from the fluid itself and its interaction with the system’s walls or components. This phenomenon occurs because of the factors such as the fluid’s velocity and viscosity, pipe characteristics like diameter and roughness, and restrictions or changes in the flow path, such as those caused by valves or bends.
Pressure lubrication – It is a system of lubrication in which the lubricant is supplied to the bearing under pressure.
Pressure measurement – It is a relative measurement which defined as either gauge or absolute. A pressure measurement can further be described by the type of measurement being performed. The three methods for measuring pressure are absolute, gauge, and differential. Absolute pressure is referenced to the pressure in a vacuum, whereas gauge and differential pressures are referenced to another pressure such as the ambient atmospheric pressure or pressure in an adjacent vessel. A pressure measurement can be described as either static or dynamic. The pressure in cases with no motion is static pressure. Frequently, the motion of a fluid changes the force applied to its surroundings. A thorough pressure measurement is to note the circumstances under which it is made. Many factors including flow, compressibility of the fluid, and external forces can affect pressure. Static pressure is uniform in all directions, so pressure measurements are independent of direction in a stationary (static) fluid. Flow, however, applies additional pressure on surfaces perpendicular to the flow direction, while having little impact on surfaces parallel to the flow direction. This directional component of pressure in a moving (dynamic) fluid is called dynamic pressure. An instrument facing the flow direction measures the sum of the static and dynamic pressures and this measurement is called the total pressure. Since dynamic pressure is referenced to static pressure, it is neither gauge nor absolute and it is known as the differential pressure. While static gauge pressure is of primary importance in determining the net loads on pipe or vessel walls, dynamic pressure is used to measure flow rates and air / gas speed. Dynamic pressure can be measured by taking the differential pressure between instruments parallel and perpendicular to the flow. The presence of the measuring instrument inevitably acts to divert flow and create turbulence, so its shape is critical to the accuracy and the calibration curves are frequently non-linear.
Pressure measurement devices – There are three distinct groups of pressure measurement devices. One is based upon the measurement of the height of a liquid column, another is based on the measurement of the distortion of an elastic pressure chamber, and a third encompasses electrical sensing devices. In liquid column pressure measuring devices the pressure is balanced against the pressure exerted by a column of a liquid with known density. The height of the liquid column directly correlates to the pressure to be measured. Majorities of the forms of liquid column measurement devices are called manometers. Elastic element pressure measuring devices are those in which the measured pressure deforms an elastic material. The magnitude of the deformation is around equivalent to the applied pressure. Different types of elastic element measuring devices include Bourdon tubes, bellows, and diaphragms. Electrical sensing devices are based on the fact that when electrical conductors are stretched elastically, their length increases while the diameter decreases. Both of these dimensional changes result in an increase in electrical resistance of the conductor. Strain gauges and piezoelectric transducers are examples of electrical pressure sensing devices. To avoid maintenance issues, the location of pressure measuring devices are to be carefully considered to protect against vibration, freezing, corrosion, temperature, and over-pressure etc. For example, in the case of a hard to handle fluid, an inert gas is sometimes used to isolate the sensing device from direct contact with the fluid. Optical fibre can be used for pressure measurement in high temperature environments.
Pressure measuring instruments – The normal pressure measuring instrument types are pressure transmitters, level probes, pressure switches, and process transmitters. Basically, these electronic pressure measuring instruments consist of a pressure connection, a pressure sensor, electronics, an electrical connection and the case. In addition, there are also simpler instrument types known as pressure sensor modules which are often consisting of no more than a pressure sensor and simple mechanical and electrical interfaces. These types are particularly suitable for complete integration into users’ systems.
Pressure media – In the context of fluid power systems, pressure media refers to the fluid, either pneumatic (gas under pressure) or hydraulic (liquid or oil under pressure), exerts force in an application. These fluids are used to transmit power and perform work in different machinery and systems.
Pressure mottling – It is non-uniform surface appearance resulting from uneven pressure distribution between adjacent layers of the product.
Pressure pipe – Pressure pipe, as distinguished from pressure tubes, is a commercial term for pipe that is used to convey fluids at higher pressure or higher temperature, or both, but which is not subjected to the external application of heat. This product is not differentiated from other types of pipes by standards, and the applicable specifications are listed with the other types of pipes. Pressure pipe ranges in size from 3 millimeters nominal to 650 millimeters actual outer diameter in different wall thicknesses. Pressure pipe is supplied in random lengths, with threaded or plain ends, as needed.
Pressure plate – It is a plate located beneath the bolster which acts against the resistance of a group of cylinders mounted to the pressure plate to provide uniform pressure throughout the press stroke when the press is symmetrically loaded.
Pressure port – It is a small, carefully made opening or connection point in a system designed to measure or control the pressure of a fluid (gas or liquid). These ports can be holes in the side of a pipe or cylinder to measure airflow, flush-mounted holes to sense static air pressure, or threaded connections on gauges or vessels for fluid power systems. The main function of a pressure port is to provide access to the fluid’s pressure, enabling monitoring or regulation within a system.
Pressure probe – It is a measuring instrument with a small tip designed to be inserted into a fluid to directly measure pressure at a specific point. It functions as a micro manometer or transducer, converting pressure into an electrical signal or visual display for applications in fluid dynamics and industrial processes.
Pressure range – It is the specified span between the lowest pressure and highest-pressure values which a measuring device, like a pressure gauge or sensor, is designed to accurately measure or a system is designed to operate within. For example, a pressure sensor with a range of 0 megapascals to 10 megapascals can accurately measure any pressure from 0 megapascals to 10 megapascals. Choosing a range with a margin above the expected maximum pressure helps ensure accurate performance and prevents damage from exceeding the device’s limits.
Pressure rating – It is the maximum pressure which a component, like a pipe, pump, or valve, is designed to safely operate at under normal conditions. It is a manufacturer-assigned value, indicated on the equipment’s data plate or in its specifications, which ensures the device functions properly without failing, leaking, or sustaining damage. Exceeding this pressure rating can lead to reduced service life or substantial equipment failure.
Pressure recovery – It is the process where the kinetic energy (velocity) of a fluid is converted into potential energy (pressure), particularly after a constriction or within a diffuser. This typically occurs when high-speed fluid enters a diverging area, slowing down and increasing its pressure.
Pressure reducing valve – It is an automatic control valve which is designed to reduce a higher unregulated inlet pressure to a constant, reduced downstream (outlet) pressure regardless of variations in demand and / or upstream (inlet) fluid pressure.
Pressure regulator – It is a valve which controls the pressure of a fluid to a desired value, using negative feedback from the controlled pressure. Regulators are used for gases and liquids, and can be an integral device with a pressure setting, a restrictor, and a sensor all in the one body, or consist of a separate pressure sensor, controller, and flow valve.
Pressure relief valves – Pressure relief valves release excess pressure to prevent system damage. They are used as a safety device to protect equipment from over-pressure occurrences in a technological process. Loss of heating and cooling, mechanical failure of valves, and poor draining and venting are some of the common causes of over-pressure. The relieving system depends on the process at hand. Pressure relief valves either bypass the fluid to an auxiliary passage or open a port to relieve the pressure to the atmosphere. Technological processes operating at high pressure normally have several pressure relief valves to follow the safety codes and procedures specified for these processes. Each of the pressure relief valves has different levels of pressure ratings to release different amounts of material to the atmosphere in order to minimize environmental impact.
Pressure roller – It is a specialized roller which is used to maintain contact between the driving belt and the load-carrying rollers within a belt-driven live roller conveyor system.
Pressure rolling process – It is a mechanical strengthening process which has some similarities to the shot peening process. It is normally applied to work-pieces with cylindrical symmetry. A roll is pressed against the work-piece to get high-compressive residual stresses. Very deep affected zones can be obtained.
Pressure-sensitive adhesive – It is a viscoelastic material which, in solvent-free form, remains permanently tacky. Such material adheres instantaneously to majority of the solid surfaces with the application of very light pressure.
Pressure sensor – It is a device which converts the mechanical pressure exerted by a gas or liquid into an electrical signal. This conversion is achieved by measuring the deformation of a diaphragm or other sensitive element within the sensor when pressure is applied. The resulting electrical signal is then processed and used to monitor or control pressure in several systems. Pressure-sensitive element is the part of the sensor that directly interacts with the pressure being measured. It can be a diaphragm, a strain gauge, or other specialized element that deforms under pressure.
Pressure signal – It is a representation of measured pressure, typically converted into an electrical output by a pressure sensor or transducer. This electrical signal, whether analog (like voltage or current) or digital, varies proportionally to the applied pressure and is then transmitted to a computer or display for interpretation, monitoring, and process control in several industrial applications.
Pressure sintering – It is a hot-pressing technique which normally uses low loads, high sintering temperatures, continuous or discontinuous sintering, and simple moulds to contain the powder. Although the terms pressure sintering and hot pressing are used interchangeably, there exist distinct differences between the two processes. In pressure sintering, the emphasis is on thermal processing, while in hot pressing, applied pressure is the main process variable.
Pressure-state-response (PSR) framework – This framework links pressures on the environment as a result of human activities, with changes in the state (condition) of the environment (land, air, water, etc.). Society then responds to these changes by instituting environmental and economic programmes and policies, which feed-back to reduce or mitigate the pressures or repair the natural resource.
Pressure steam – It is water vapour maintained at a pressure above atmospheric pressure, typically used for industrial applications because of its higher energy content and ability to reach temperatures above 100 deg C. The term ‘pressure steam’ frequently distinguishes it from steam generated at or below atmospheric pressure, with specific pressure thresholds defining ‘low-pressure’ and ‘high-pressure’ steam depending on the application and regulatory standards.
Pressure surge – It is a transient and potentially destructive increase or decrease in fluid pressure within a pipeline or system, caused by sudden changes in flow velocity, such as those occurring during valve closures, pump startups, or the presence of air pockets. This phenomenon, frequently known as water hammer or fluid hammer, generates a pressure wave which travels through the system, potentially causing fatigue, leaks, or ruptures in pipes and equipment.
Pressure swing adsorption (PSA) – It is a technique which is used to separate some gas species from a mixture of gases (typically air) under pressure as per the species’ molecular characteristics and affinity for an adsorbent material. It operates at near-ambient temperature and significantly differs from the cryogenic distillation which is normally used to separate gases. Selective adsorbent materials such as zeolites (also known as molecular sieves), and activated carbon etc. are used as trapping material, preferentially adsorbing the target gas species at high pressure. The process then swings to low pressure to desorb the adsorbed gas. The pressure swing adsorption process is based on the phenomenon that under high pressure, gases tend to be trapped onto solid surfaces, i.e., to be ‘adsorbed’. The higher the pressure, the more gas is adsorbed. When the pressure is dropped, the gas is released, or desorbed.
Pressure swing distillation (PSD) – It is a method that makes use of the pressure sensitivity of azeotropic mixtures for separation. Hence, by designing more than one column operating at significantly different pressures, the distillation boundaries are shifted so that the separation can be achieved.
Pressure switch – In several applications electronic pressure switches replace the mechanical pressure switches which were earlier very commonly used. This is because they offer, as a result of their design principle, additional functions such as digital display, adjustable switch points and considerably higher reliability. An electronic pressure switch is based on an electronic pressure transmitter and hence offers the entire functionality of a transmitter. With the integrated electronic switch, which can close or open an electrical circuit, it is able to perform simple control tasks. The switch point and the reset point can be set individually. By default, a pressure-switch only outputs binary signals such as switch point or reset point ‘reached’ or ‘not reached’ but it does not output how far the measured pressure is from the switch or reset point. Hence, several pressure switches have a display and additionally an analog output signal. The set parameters and measured pressure can be read off the display. In addition, the measured pressure can be transmitted by the analog output signal to a downstream control unit. Hence, the widely adopted type of electronic pressure switch includes a switch, a pressure transmitter and a digital indicator, all in one instrument.
Pressure tank – It is a storage container which holds liquids or gases under pressure higher than atmospheric pressure, frequently used to maintain a steady supply or buffer variations in pressure within a system, such as in water supply systems to prevent frequent pump cycling. These tanks are designed to operate within specific pressure ranges to ensure the safety and efficiency of the system they are part of.
Pressure thermometer – It is a device which measures temperature by sensing the pressure changes of a confined fluid (liquid or gas) caused by temperature variations. As temperature increases, the fluid expands and creates more pressure and as it decreases, it contracts and creates less pressure. This pressure change is then converted by a Bourdon tube or similar mechanism into a displacement, which operates a pointer on a scale to indicate the temperature.
Pressure test – It is a hydraulic or pneumatic test for pipes and tubes to prove that they material can withstand a specified pressure for a specified time without leakage or rupture.
Pressure testing method – It is a method of leak testing in which the component being tested is filled completely with a gas or liquid which is then pressurized. The outside of the component is examined for the detection of any leaks.
Pressure-tight – It means a casting or structure is free from porosity or defects, which allow leakage of a liquid or gas under pressure. Essentially, it describes a component’s ability to withstand pressure without any seepage or loss of the substance being contained, according to engineering resources.
Pressure transducer – Pressure transducers are normally available in a multitude of sensor modules which can be directly matched to the requirements of the process. They have, for example, a user-specific pressure connection and / or a user-specific electric interface. Only very few suppliers of electronic pressure measurement technology even offer the so-called ‘bare’ pressure sensor as a module. For these, the users are to develop their own design solutions in order to get the pressure to the sensor and evaluate the sensor signal. For pressure transducers, it is normally the case that their correct function is to be ensured by the user’s design-related measures. Hence, this option is generally only suitable for mass-produced equipment.
Pressure transmitter – A pressure transmitter has standardized interfaces, both on the process side and on the electrical output signal side, and converts the physical pressure value to a standard industrial signal. The pressure connection is used to lead the pressure directly onto the sensor. It has a ‘standardized’ thread and an integrated sealing system to enable easy connection of the pressure transmitter simply by screwing it in at the relevant measuring point. A suitable case protects the sensor and the electronics against environmental influences. The electronics transform a weak sensor signal into a standardized and temperature compensated signal (e.g., the common industrial signal of 4-20 mA). The output signal is transmitted through a ‘standardized’ plug or cable for subsequent signal evaluation.
Pressure tube reactor – It is a type of nuclear reactor that contains the fuel and primary coolant within numerous individual pressure tubes, each housing a fuel channel, rather than a large, single pressure vessel. These pressure tubes are arranged within a larger moderator tank and are surrounded by a moderator fluid. This design improves safety, as the failure of one tube does not compromise the integrity of the entire reactor system.
Pressure tubes – Pressure tubes are given a separate classification by both the standards and the manufacturers. The chemical composition limits for carbon steel and for alloy steel as well as the strength requirements are covered in the standards for these tubes. Pressure tubes are distinguished from pressure pipes in that they are suitable for the application of external heat while conveying pressurized fluids. Pressure tubes are used in different components of the boilers. These tubes are produced to actual outside diameter and minimum or average wall thickness (as specified by the user) and can be hot finished or cold finished, as needed.
Pressure tunnel – It is an underground conduit, or tunnel, which conveys fluids, very frequently water, under pressure, typically for hydroelectric power generation. These tunnels are lined with different materials to prevent leaks and withstand the substantial internal hydraulic pressure from the conveyed fluid. They can also be designed for air flow management in high-speed rail applications, where pressure transients and sonic effects are to be controlled.
Pressure turbine – It is a rotary engine which extracts energy from a high-pressure fluid, such as steam or gas, to create mechanical work by rotating a shaft with blades. It works by directing a high-velocity stream of fluid across a series of moving blades, causing them to rotate and impart rotational energy to the turbine’s central spindle.
Pressure under steel cords on pulley – As a rule of thumb, the pressure between steel cord and pulley is not to be higher than 2 megapascal.
Pressure vacuum swing adsorption (PVSA) – It is a gas separation technology which uses a repeating cycle of high-pressure adsorption and low-pressure (vacuum) desorption to separate a target gas from a mixture. The process relies on an adsorbent material, such as a zeolite, which selectively captures and holds gas molecules based on their affinity and the current pressure, allowing for purification of gases like hydrogen, oxygen, and methane.
Pressure vessel – It is a container designed to hold gases or liquids at a pressure substantially different from the ambient pressure. In nuclear power plant a pressure vessel is a closed, strong-walled container housing the core of most power reactors and designed to hold gases or liquids at high pressures. It also normally contains the moderator, neutron reflector, thermal shield, and control rods.
Pressure vessel code – It is a comprehensive set of standards and guidelines which dictate the safe design, manufacturing, inspection, testing, and operation of pressure vessels to ensure they can contain fluids or gases at high pressures without incident. These codes provide technical specifications and requirements for materials, fabrication methods, and different testing procedures. This code is updated regularly by industry experts to incorporate new technologies.
Pressure-viscosity coefficient – It is the slope of a graph showing variation in the logarithm of viscosity with pressure. The use of the term pressure-viscosity coefficient assumes a linear relationship.
Pressure 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 filler metal. Pressure may or may not be applied to the joint. The pressure welding processes are cold welding, diffusion welding, forge welding, hot pressure welding, pressure-controlled welding, pressure gas welding, and solid-state welding.
Pressurized gas – It is a gas stored in a container at a pressure considerably above the surrounding atmospheric pressure, frequently containing a substantial quantity of kinetic energy and posing risks like leaks or bursts. This includes gases classified as compressed, liquefied, or dissolved, and they are used in different industrial processes.
Pressurized gas lubrication – It is a system of lubrication in which a gaseous lubricant is supplied under sufficient external pressure to separate the opposing surfaces by a gas film.
Pressurized heavy water reactor – It is a reactor type which uses natural uranium as its fuel and heavy water as the coolant.
Pressurized tank – It is also called pressure vessel. It is a sealed container designed to store and transport gases or liquids at a pressure considerably higher than the surrounding atmospheric pressure. These tanks are engineered with specialized designs and robust materials to safely contain the contents, prevent leaks, and resist the internal pressure during operation. They are necessary in various industries and applications, from storing industrial gases like propane and natural gas to maintaining water pressure in well systems.
Pressurized water reactor – It is a reactor whose primary coolant is maintained under such a pressure that no bulk boiling occurs. The reactor uses light water as a moderator and as a coolant.
Preston tube – It is a simple, wall-mounted Pitot tube used in fluid dynamics to measure the skin friction (local wall shear stress) in a turbulent flow. It works by relating the stagnation pressure measured by the tube, which rests directly on the surface, to the wall shear stress through a calibration curve. This method is convenient and widely used since it assumes a universal law of the wall, suggesting that the wall layer properties are similar in different turbulent flows, allowing the Pitot tube’s dynamic pressure reading to be correlated with the local shear stress.
Prestressed beam – It is a concrete structural member where internal compressive forces are introduced to counteract the tensile stresses which otherwise occur when the beam is subjected to external loads, preventing cracking and improving durability. These internal forces are applied using high-strength steel tendons or wires, which are either tensioned before concrete placement (pre-tensioning) or tensioned after concrete hardens within ducts (post-tensioning).
Pre-stressed concrete – It is a form of concrete which is used in construction. It is substantially ‘prestressed’ (compressed) during production, in a manner which strengthens it against tensile forces which exist when in service. This compression is produced by the tensioning of high-strength ‘tendons’ located within or adjacent to the concrete and is done to improve the performance of the concrete in service. Tendons can consist of single wires, multi-wire strands or threaded bars which are normally made from high-tensile steels, carbon fibre or aramid fibre. The essence of prestressed concrete is that once the initial compression has been applied, the resulting material has the characteristics of high-strength concrete when subject to any subsequent compression forces and of ductile high-strength steel when subject to tension forces. This can result in improved structural capacity and / or serviceability compared with conventionally reinforced concrete in several situations.
Pre-stressed structure – It is a load-bearing structure whose overall integrity, stability, and security depend, primarily, on prestressing which is the intentional creation of permanent stresses in the structure for the purpose of improving its performance under different service conditions. The basic types of prestressing are (i) pre-compression with mostly the structure’s own weight, (ii) pre-tensioning with high-strength embedded tendons, and (iii) post-tensioning with high-strength bonded or unbonded tendons.
Pre-supposition – It is an underlying, taken-for-granted assumption necessary for a theory, an argument, or a design to be valid or meaningful. These implicit premises, which can be beliefs about natural laws, existing conditions, or functional relationships, serve as the foundation upon which engineering solutions and scientific conclusions are built, similar to how they function in other fields of knowledge.
Pre-tinning – It is a non-standard term for precoating.
Pre-treatment – It refers to a preparatory process or series of operations performed on a material, substance, or waste before a main treatment or primary processing step, aiming to improve efficiency, improve desired qualities, facilitate downstream operations, or meet specific discharge / disposal requirements. In case of galvanizing, It is subjecting steel to specific processes before galvanizing.
Pre-vapourizer – It is used during hydro-refining of crude benzol. It consists of a vertically mounted shell and tube heat exchanger. The feed is mixed with a part of recycles gas (containing H2 gas around 15 % of the total gas) before it is fed to the vaporizer. This feed is heated to around 160 deg C to 165 deg C by means of the main reactor effluent passing through shell side. The heated feed which is at a temperature of 160 deg C to 165 deg C is fed to the third mixing nozzle of stage evaporator. Pre-vaporizer is provided with turbulence promoters in the tube side to achieve high turbulence so that more heat exchange can occur and no scale formation is attained. This arrangement is provided as the feedstock in partial vapour stage (gas-liquid stage) to prevent rapid fouling of the tubes. This arrangement also provides easy cleaning of the tubes by simply pulling the turbulence promoters.
Prevention costs – These are the costs of the actions taken to make sure that things do not go wrong in the organization. Prevention costs to avoid failures are the necessary costs. Inspection costs are the costs of finding out if things are going on correctly so that in case of a deviation, corrective and preventive actions can be taken. Defect prevention cost comes under this category of costs.
Prevention of significant deterioration (PSD) program – It applies to the construction of new major stationary sources and to major modifications of existing stationary sources. It also applies to modifications of existing minor stationary sources if the modification itself constitutes a major source. The basic goals of this program are to (i) ensure that economic growth occurs in harmony with the preservation of existing clean air resources, (ii) protect the public health and welfare from any adverse effects which can occur, and (iii) preserve, protect, and improve the air quality in areas of special natural, recreational, scenic or historic value.
Preventive action – It is a proactive way to prevent potential problems before they occur. It is a key part of quality management systems and is frequently used in conjunction with the corrective action.
Preventive control – It is a proactive measure designed to stop a problem, error, or undesirable event from occurring in the first place by implementing mechanisms or strategies which deter or block it before it happens. These controls are built into processes or systems to eliminate potential issues, mitigate risks, and ensure safety and compliance. Examples include using firewalls to prevent unauthorized access, implementing safety guards on machinery, or establishing rigorous maintenance and sanitation protocols for equipment.
Preventive maintenance – It is defined as ‘actions performed on a time or machine run based schedule which detect, preclude, or mitigate degradation of a component or equipment with the aim of sustaining or extending its useful life through controlling degradation to an acceptable level’. Preventive maintenance is carried out at pre-determined intervals or corresponding to prescribed criteria and intended to reduce the probability of failure or the performance degradation of an item. The maintenance cycles are planned as per the need and the incidence of operating faults is reduced.
Preventive order – It is a legislation-based command to prevent environmental, natural resource, or safety issues.
Price forecasting – It refers to the process of predicting future market prices based on analysis of historical data and several influencing factors, including economic, industry-specific, organization-specific, psychological, and political variables. It involves utilizing statistical and artificial intelligence techniques to achieve accurate and reliable predictions in the dynamic and complex market environment.
Price optimization process – It is the mathematical program which calculates how demand varies at different price levels then combines that data with information on costs and inventory levels to recommend prices that will improve profits. The process allows organizations to use pricing as a powerful profit lever, which often is underdeveloped. Price optimization process is used to tailor pricing for customer segments by simulating how targeted customers respond to price changes with data driven scenarios. Given the complexity of pricing thousands of items in highly dynamic market conditions, the results and insights obtained through the price optimization process help to forecast demand, develop pricing and promotion strategies, control inventory levels and improve customer satisfaction. Price optimization process is to factor in three critical pricing elements namely (i) pricing strategy, (ii) the value of the product to both buyer and seller, and (iii) tactics that manage all elements affecting profitability.
Price-to-earnings ratio – The current market price of a stock divided by the organization’s net earnings per share for the year.
Primary – It is the simplest, most commonly known, or canonical form of a chemical compound with multiple similar or isomeric forms. For example, in a primary alcohol, the carbon is bonded to a single substituent group (R1CH2OH), whereas a secondary alcohol is doubly substituted (R1R2CHOH) and a tertiary alcohol is triply substituted (R1R2R3COH). In case of X-ray, primary is the beam incident on the sample.
Primary air – In the context of combustion systems like boilers and furnaces, it refers to the initial quantity of air introduced to the fuel stream before the main combustion process. It is the air which mixes with the fuel at the start, helping to initiate and control the burning process.
Primary air pollutants – These are substances emitted directly from identifiable sources, such as volcanic eruptions, industrial processes, vehicles, and the burning of fossil fuels, rather than being formed in the atmosphere by chemical reactions. Common examples of primary air pollutants include sulphur di-oxide (SO2), nitrogen oxides (NOx), carbon mono-oxide (CO), and suspended particulate matter (PM). These pollutants can cause immediate harm to human health and the environment in their original, unmodified form.
Primary alkaline battery – It is a type of electro-chemical cell which utilizes a zinc anode and manganese di-oxide cathode, featuring an alkaline electrolyte, which results in higher energy density, longer shelf life, and lower leakage compared to zinc-carbon batteries. It operates through redox reactions, producing an open-circuit voltage of around 1.6 volts.
Primary alloy – It is any alloy whose major constituent has been refined directly from ore, and not recycled scrap metal.
Primary alpha – It is the alpha phase in a crystallographic structure which is retained from the last high-temperature alpha-beta working or heat treatment. The morphology of alpha is influenced by the prior thermo-mechanical history.
Primary amine – It is an organic compound characterized by a nitrogen atom bonded to one alkyl or aryl group and two hydrogen atoms, represented by the general formula R-NH2. In essence, it is a derivative of ammonia (NH3) where one hydrogen atom has been replaced by a carbon-containing group.
Primary atomization – It is the initial physical process where a bulk liquid, exiting a nozzle as a jet or sheet, undergoes disintegration into ligaments and larger droplets due to interactions with a surrounding gas. This foundational stage is driven by forces like aerodynamic drag, surface tension, and liquid viscosity, which work to break the continuous liquid flow into a dispersed spray, determining the initial characteristics of droplets and filaments.
Primary boiling – It is the evolution of gas during the initial firing of porcelain enamel. It is sometimes considered a defect.
Primary choke – It is that part of the gating system which most restricts or regulates the flow of metal into the mould cavity.
Primary circuit – It refers to the input side of a system, such as the input side of a transformer or an isolated power supply, where the main electrical power is applied. It serves as the first stage or a foundational part of a larger electrical system, frequently handling higher or dangerous voltage levels and containing components like circuit breakers for protection. The term can also describe the input loop in other systems, like the pipe network in geothermal systems that circulates heat-carrying fluid.
Primary coil – It is the coil in a transformer which is connected to the input voltage source. It is responsible for generating a magnetic field when an alternating current flows through it, which induces a voltage in the secondary coil. This process is crucial for transforming electrical energy from one voltage level to another, highlighting the primary coil’s role in efficient power transmission.
Primary combustion zone – It is the initial region within a combustion chamber where a portion of the fuel and air are mixed and rapidly ignited to stabilize the flame and initiate the combustion process. This zone creates a highly turbulent, fuel-rich environment which promotes the formation of a stable, self-sustaining flame. The primary zone is designed to achieve complete combustion by providing sufficient temperature, time, and turbulence for the fuel-air mixture, frequently by creating a recirculation zone.
Primary composite structure – It is a critical component made from a composite material, meaning it consists of two or more different constituent materials with distinct properties which work together to achieve superior performance, such as high strength, stiffness, and fatigue resistance, over any single component alone. These primary structures bear substantial loads and are vital for the overall integrity and safety of a system.
Primary compression – It is the rapid initial reduction in volume of a material under an applied load, driven by the expulsion of pore fluid and an increase in effective stress, leading to a change in the material’s void ratio. This contrasts with secondary compression, which is a slower process occurring at constant effective stress, and tertiary compression which is a further, more complex volume reduction. Primary compression is a key concept in soil mechanics, describing the first stage of consolidation under load.
Primary controller – It can refer to the initial or foundational control system responsible for local, high-speed response to immediate system changes, like in a hierarchical control system, or it can mean a critical engineering control. The specific definition depends on the engineering domain, with common examples including local control for grid stability using droop methods or unidirectional airflow workstations to control airborne particles in a cleanroom.
Primary coolant – It is the working fluid which circulates within a nuclear reactor’s primary cooling loop to remove heat from the reactor core, transfer it to a secondary system for power generation, and help maintain the integrity and safety of the reactor. It serves as a direct medium for both heat transfer and, in some designs, neutron moderation and absorption.
Primary cooling – In the context of heat transfer systems, it refers to the initial stage of removing heat from a system or process, frequently involving a coolant which circulates through a closed loop and absorbs heat. This heated coolant is then directed to a secondary cooling system or heat exchanger where the heat is ultimately dissipated to the environment. The primary cooling loop typically involves a fluid (coolant) circulating through a system or component which generates heat. This coolant absorbs the heat, effectively lowering the temperature of the source. A primary cooling loop is frequently a closed circuit, meaning the coolant circulates within the system without being directly exposed to the environment. This helps to maintain the purity and efficiency of the coolant.
Primary cooling zone – In a continuous casting machine, it consists of water-cooled copper mould through which the liquid steel is fed from the tundish for generating a solidified outer steel shell sufficiently strong enough to maintain the strand shape as it passes into the secondary cooling zone.
Primary creep – It is the first, or initial, stage of creep, or time-dependent deformation.
Primary crusher – It breaks up large pieces of rock or concrete from the blasting or excavation process and turns them into smaller, more manageable chunks. This is the first step in the crushing process. The smaller pieces can then either be pre-screened or fed directly into a secondary impact or cone crusher.
Primary crushing – In an ore mine, it is the first crushing of mined ore.in the process. Run of Mine (ROM) materials are brought directly from the blasting areas and crushed in a primary crusher for the first round of crushing. At this point, the material receives its first reduction in size from its raw state. Two types of crushers which are used in primary crushing are jaw crusher and gyratory crusher.
Primary crystals – It is the first type of crystals which separate from a melt during solidification. It is the first dendritic crystal which form in an alloy during cooling below the liquid’s temperature.
Primary current distribution – It is the current distribution in an electrolytic cell which is free of polarization. It refers to the theoretical distribution of electric current within the electrolyte, solely based on the resistance of the solution, neglecting any effects of electrode kinetics (overpotential) or concentration gradients, essentially showing how current would flow if the only factor affecting its distribution was the electrolyte’s resistivity and cell geometry; it is considered a simplified model to analyze the basic current flow patterns within the cell.
Primary deposits – These are valuable minerals deposited during the original period or periods of mineralization, as opposed to those deposited as a result of alteration or weathering.
Primary energy – It refers to raw energy found in nature which has not undergone any human-engineered conversion or transformation. It is the form of energy available in natural resources such as crude oil, coal, natural gas, solar, wind, and nuclear fuel, before it is extracted, processed, and converted into secondary energy carriers like electricity. Primary energy serves as the input for energy systems, with secondary energy being the transformed product used by society.
Primary energy consumption – It measures the total energy demand of a country. It covers consumption of the energy sector itself, losses during transformation (for example, from oil or gas into electricity) and distribution of energy, and the final consumption by end users. It excludes energy carriers used for non-energy purposes (such as petroleum not used not for combustion but for producing plastics).
Primary estimate – It is also called a preliminary or rough estimate. It is an initial cost calculation performed at the very beginning of a project when only limited information is available. It provides a broad, approximate idea of the project’s total cost, used for feasibility assessment, budget consultation, and getting early administrative approval, frequently based on historical data from similar past projects.
Primary etching – It is the development of cast structures including coring.
Primary extinction – It is a decrease in intensity of a diffracted X-ray beam which is caused by perfection of crystal structure extending over such a distance (around 1 micrometer or higher) that interference between multiply reflected beams inside the crystal decreases the intensity of the externally diffracted beam.
Primary facility – It refers to a main, stand-alone physical asset or system which provides a core function or service, such as a production plant. It is distinct from support facilities which serve a primary one and is designed to operate independently to deliver its intended purpose.
Primary flow – It refers to the main, high-pressure driving fluid stream in a device, such as an ejector, which mixes with a lower-pressure secondary flow to achieve a desired effect. It can also refer to the primary flow element, a device like an orifice plate or Venturi tube which creates a measurable physical property, such as a pressure drop, directly proportional to the main fluid flow rate.
Primary fuels – These are the fuels which are found in nature and can be extracted, captured, cleaned, or graded without any sort of energy conversion or transformation process. This means that all processing and collecting of the fuel is done before the fuel is converted into heat or mechanical work. These primary fuels tend to be non-renewable, and some of the most commonly known primary fuels are fossil fuels.
Primary gas porosity – It is formed during the initial solidification of the metal. It is developed because of the hydrogen precipitation in a molecular form in a smelt or in the front of crystallization.
Primary inductance – It refers to the self-inductance of the primary winding of a transformer, which is its ability to store magnetic energy and oppose changes in the primary current by generating an opposing electromotive force (EMF). It contributes to the total magnetic flux linking the core and is proportional to the primary’s number of turns, core material, and geometry.
Primary instruments – These are also called absolute instruments. These instruments are those instruments which give the value of electrical quantity to be measured in terms of the constants of the instruments and their deflection only e.g. tangent galvanometer. These instruments are rarely used except in standard laboratories, especially for calibration of secondary instruments. Working with absolute instruments for routine work is time consuming since every time a measurement is made, it takes a lot of time to compute the magnitude of the quantity under measurement. The use of the absolute instruments is simply confined within laboratories as standardizing instruments.
Primary ion – It is an atom or molecule intentionally created and accelerated into a beam to bombard a solid surface in techniques like secondary ion mass spectrometry (SIMS) and ion beam analysis. This bombardment transfers energy to the target atoms, causing a cascade of collisions that leads to the ejection of some surface atoms as secondary ions, which are then analyzed.
Primary knock-on atom (PKA) – It is the first atom in a material to be displaced from its lattice position by an incident particle, such as a neutron or electron. When this incident particle collides with a target atom, it transfers energy to it. If the energy transfer is sufficient, the target atom is ejected from its lattice site, becoming the primary knock-on atom. This primary knock-on atom can then initiate a cascade of further atomic displacements.
Primary leakage – In seals, it is the leakage of a mechanical seal, with the fluid escaping from the region between the end faces of the primary sealing elements.
Primary metal – It is the metal which is extracted from minerals and free of reclaimed metal scrap.
Primary mill – It is a mill for rolling ingots or the rolled products of ingots to blooms, billets, or slabs. This type of mill is frequently called a blooming mill or slabbing mill and sometimes called a cogging mill.
Primary mining – It refers to the initial extraction of raw materials directly from the earth, utilizing large-scale equipment to recover minerals, ores, and fossil fuels like coal and metals from deposits like seams or veins. It is the fundamental stage of a mine’s life cycle, involving processes such as drilling, shoveling, and hauling, which are critical for gathering material that is then further processed and refined to create products for shipment.
Primary nozzle – It is a component, frequently a shaped opening, designed to control and direct the flow of a working fluid, such as liquid or gas, to convert its pressure energy into kinetic energy, hence increasing its velocity. Its specific shape and size influence the fluid’s flow rate, speed, direction, and pattern, making it a critical component for system performance in a wide range of applications such as turbines and industrial processes.
Primary nucleation – It is the initial formation of a crystal, or another new phase, in a previously crystal-free system. It is a spontaneous process driven by supersaturation and can be either homogeneous nucleation (occurring without any external influence, though rarely in practice) or heterogeneous nucleation (induced by the presence of foreign particles, which is common in industrial processes). This is a crucial first step in several crystallization processes, establishing the first stable nuclei from which larger crystals can grow.
Primary oxidation – It can refer to two distinct concepts namely (i) the initial formation of conjugated diene hydroperoxides in a substance, or (ii) the more general process of oxidation as the early-stage degradation of materials by reacting with oxygen, leading to weakening of their properties. The specific definition depends on the context, such as polymer degradation or material synthesis.
Primary passive potential (passivation potential) – It is the potential corresponding to the maximum active current density (critical anodic current density) of an electrode which shows active-passive corrosion behaviour.
Primary pollutants – These are those substances which are directly produced by a process, such as ash from a volcanic eruption or carbon mono-oxide gas from the exhaust of an automobile. Primary pollutants can be transformed in the lower atmosphere by solar radiation and heat or by chemical action in the atmosphere into secondary pollutants, such as ozone and other photochemical pollutants or acid rain. Primary air pollutants are emitted directly into the air from sources. They can have effects both directly and as precursors of secondary air pollutants.
Primary pore – It is a void space within a material that originates from its initial depositional or formation process, existing as the space between grains (intergranular) or within grains (intragranular) from the outset. Unlike secondary pores, which form later through processes like dissolution or fracturing, primary pores are a fundamental part of the material’s original structure. They are important in understanding the porosity of materials like soils, rocks, and engineered scaffolds, as they directly relate to the material’s mechanical and fluid transport properties.
Primary processing discontinuities – Primary processing discontinuities refer to the discontinuities which originate during hot or cold forming processes such as rolling, forging, extrusion, drawing, and welding etc. Also, some of the inherent discontinuities in the material can propagate and become significant.
Primary protection – In power system, it is the first line of defense against faults, designed to quickly and selectively isolate a faulty component or section of a system. It uses its own protective relays and circuit breakers to clear faults within its designated protection zone, acting as the main or primary system response. If this primary system fails, a secondary backup protection scheme is in place to ensure the fault is still cleared, preventing widespread damage.
Primary reference standard – It is a material, instrument, or quantity which possesses the highest level of purity and stability, serving as the ultimate benchmark for measurement and analysis. Its value is established through rigorous analytical testing and is accepted as the reference without needing comparison to other standards. Examples include a substance of exceptional purity, a deadweight tester for pressure, or a national standard like the kilogram artifact, to which all other secondary standards are calibrated and traceable.
Primary scale – It is composed of three well defined layers of iron oxides. Adjacent to the steel is the thickest layer consisting of wustite having an approximate composition of FeO. The intermediate layer consists of magnetite (Fe3O4) while the outermost layer is hematite (Fe2O3). The thicknesses of these layers depend on several factors linked to the rolling of the steel and the availability of oxygen at the steel surface. The layer at the surface of the steel is richest in oxygen and constitutes 0.5 % to 2 % of scale thickness. The layer at the metal surface is richest in iron and constitutes about 85 % of the scale thickness. The intermediate layer of scale constitutes around 13 % to 14.5 % of scale thickness.
Primary sector – It refers to the stage of production which involves extracting, harvesting, and collecting raw materials directly from the environment. Engineering plays a role within the primary sector by improving the efficiency and methods of resource extraction, such as in mining.
Primary sensing element (PSE) – It is a device directly sensing the process variable and translating the sensed quantity into an analog representation (electrical voltage, current, resistance, mechanical force, or motion etc. Examples are thermocouple, thermistor, bourdon tube, microphone, potentiometer, electro-chemical cell, and accelerometer etc.
Primary shaping processes – In these processes, the material initially has no shape but gets a well-defined geometry through the process. Examples are casting, melt extrusion, die casting, and pressing of metal powder.
Primary sludge – It is the semi-solid material consisting of settleable organic and inorganic solids, oils, and grease which is removed from raw wastewater through gravity in a primary clarifier during the first stage of wastewater treatment. It is drawn from the bottom of the sedimentation tank after suspended solids have settled out.
Primary standard – It is a standard which is designated or widely acknowledged as having the highest metrological qualities and whose value is accepted without reference to other standards of the same quantity. The concept of primary standard is equally valid for base quantities and derived quantities.
Primary steel producer – It is also called integrated steel producer. It is a steel manufacturer which starts its process with raw iron ore, converting it into crude steel through an integrated steel plant using a blast furnace and a basic oxygen furnace (BOF), or an electric arc furnace and then refining and casting it into primary steel products.
Primary voltage – It is the input voltage supplied to the primary winding of a transformer from the power source. It is the voltage of the circuit which feeds the transformer, which can then, through the principle of magnetic induction and the transformer’s turns ratio, step the voltage up or down to create a different secondary voltage for a load.
Primary waste-water treatment – It is the removal of particulate materials from waste-water, normally done by allowing the solid materials to settle as a result of gravity. Typically, it is the first major stage of treatment encountered by the waste-water as it enters a treatment facility. Primary treatment plants normally remove 25 % to 35 % of the biological oxygen demand (BOD) and 45 % to 65 % of the total suspended matter. It is also a process which used for the decomposition, stabilization, or disposal of sludges produced by settling.
Primary winding – Primary winding of transformers is the coil which draws power from the source. Transformers have separate coils, and contain several turns of wire and a magnetic core, which forms a path for and concentrates the magnetic flux. The winding receiving electrical energy from the source is called the primary winding. The winding which receives energy from the primary winding, through the magnetic field, is called the secondary winding. Either the high-voltage or low-voltage winding can be the primary or the secondary. With generator set-up at power plants, the primary winding is the low-voltage side (generator voltage), and the high voltage side is the secondary winding (transmission voltage). Where power is used, the primary winding is the high-voltage side, and the secondary winding is the low-voltage side.
Primary X-ray – It is the emergent beam from the X-ray source.
Prime material – It refers to the material which meets all the rigorous quality standards set during manufacturing. It is essentially a product which has passed all manufacturing inspection tests and is considered to be of the highest quality. Anything which does not meet these standards is considered secondary material. Manufacturer provides a rest certificate for the prime material.
Prime mover – A prime mover is defined to be a machine which transforms energy from thermal, electrical, or pressure form to mechanical form, typically an engine or turbine. It is the heart of an energy system. Normally, the output of a prime mover is the rotary motion, so it is always being used to couple with an electric generator.
Primer – It is also known as undercoat. It is a preparatory coating put on materials before painting. Primer ensures better adhesion of paint to the surface, increases paint durability, and provides additional protection for the material being painted.
Primer coat – It is the initial protective or foundational layer applied to a surface before subsequent coats, designed to improve adhesion, provide corrosion or moisture protection, and create a stable, smooth base for better overall performance of the material or coating system. The specific formulation and function of a primer vary depending on the substrate (e.g., metal, wood, asphalt) and the desired outcome, such as improved durability, chip resistance, or better color consistency in a painting system or increased stability in a road construction application.
Primes – It consists of metal products, principally sheet and plate, of the highest quality and free from blemishes or other visible imperfections.
Priming – It is the discharge of steam containing excessive quantities of water in suspension from a boiler, because of violent effusion. It is the representation of wetness fraction in percentage.
Priming a pump – Typically, a liquid pump cannot simply draw air. The feed line of the pump and the internal body surrounding the pumping mechanism is first to be filled with the liquid which needs pumping. An operator is required to introduce liquid into the system to initiate the pumping. This is known as priming the pump. Loss of prime is normally because of the ingestion of air into the pump, or evaporation of the working fluid if the pump is used infrequently. Clearances and displacement ratios in pumps for liquids are insufficient for pumping compressible gas, so air or other gasses in the pump cannot be evacuated by the pump’s action alone. This is the case with majority of the velocity (rotodynamic) pumps, e.g., centrifugal pumps. For such pumps, the position of the pump and intake tubing is to be lower than the suction point so it is primed by gravity. Otherwise, the pump is to be manually filled with liquid or a secondary pump is to be used until all air is removed from the suction line and the pump casing. Liquid ring pumps have a dedicated intake for the priming liquid separate from the intake of the fluid being pumped, as the fluid being pumped can be a gas or mix of gas, liquid, and solids. For these pumps the priming liquid intake is to be supplied continuously (either by gravity or pressure), however the intake for the fluid being pumped is capable of drawing a vacuum equivalent to the boiling point of the priming liquid. Positive-displacement pumps, however, tend to have sufficiently tight sealing between the moving parts and the casing or housing of the pump that they can be described as self-priming. Such pumps can also serve as priming pumps, so-called when they are used to fulfill that need for other pumps in lieu of action taken by a human operator.
Primordial element – It is a chemical element with at least one primordial nuclide. There are 251 stable primordial nuclides and 35 radioactive primordial nuclides, but only 80 primordial stable elements —hydrogen through lead, atomic numbers 1 to 82, except for technetium (43) and promethium (61) — and three radioactive primordial elements — bismuth (83), thorium (90), and uranium (92). If plutonium (94) turns out to be primordial (specifically, the long-lived isotope 244Pu), then it is to be a fourth radioactive primordial, though practically speaking it would still be more convenient to produce synthetically.
Principal axis – It refers to a specific axis related to a body or system, defined by its properties, such as being an axis of maximum or minimum moment of inertia, a line of symmetry, or a key directional component in a dataset. For example, in mechanical engineering, principal axes of inertia are three mutually perpendicular axes through a body’s centre of mass which allow angular momentum and angular velocity to be aligned. In optics, the principal axis is the line passing through the optical centres of lenses or mirrors, while in data analysis, principal axes are derived from principal component analysis (PCA) to identify the directions of maximum statistical variance in a dataset.
Principal components – These are new, uncorrelated variables which represent the directions of maximum variance in a dataset, identified through a statistical technique called principal component analysis (PCA). They serve to reduce the dimensionality of complex, high-dimensional data by capturing most of the original information in a smaller number of principal components, making the data easier to analyze, visualize, and use for tasks like data compression and feature extraction.
Principal radius of curvature – It describes the curvature of a surface at a given point, specifically the two perpendicular radii corresponding to the maximum and minimum curvature values. These radii are determined by considering all possible planes through the point of interest, finding the directions where the surface curves most and least. The concept is applied in fields like solid mechanics to analyze stress distribution and in materials science to characterize the geometry of pores and other features.
Principal stress (normal) – It is the maximum or minimum value of the normal stress at a point in a plane considered with respect to all possible orientations of the considered plane. On such principal planes the shear stress is zero. There are three principal stresses on three mutually perpendicular planes. The state of stress at a point can be (i) uniaxial, which is a state of stress in which two of the three principal stresses are zero, (ii) biaxial, which is a state of stress in which only one of the three principal stresses is zero, and (iii) triaxial, which is a state of stress in which none of the principal stresses is zero. Multiaxial stress refers to either biaxial or triaxial stress.
Principal structural element – It is an element of structure which contributes considerably to the carrying of flight, ground, or pressurization loads and whose integrity is essential in maintaining the overall structural integrity of the airplane.
Principal views – In engineering and technical drawing, it refers to a set of standard orthographic projections used to represent a 3D object in 2D. These views are typically the front, top, and right-side views, though other views like the left side, bottom, and rear views can also be included. They are crucial for clearly communicating an object’s shape, dimensions, and features.
Principle of conservation of energy – It states that the total energy within a closed system remains constant over time, even though it can be transformed from one form to another. Energy cannot be created or destroyed, meaning that in any engineering application, the sum of all input energy is to be equal the sum of all output energy, including useful work, heat, and other forms of energy, plus any stored energy.
Principle of conservation of mass – It states that for a closed system or a defined control volume, the total mass remains constant over time, i.e., mass cannot be created or destroyed but only changed in form or moved between systems. This fundamental concept is applied to track and balance the flow of materials, necessary for designing processes, optimizing equipment, and predicting system behaviour in fields like chemical and fluid engineering.
Principle of corresponding states (PCS) – It is a principle stating that different fluids behave similarly when compared at the same reduced temperature, pressure, and volume. These reduced properties, normalized by each substance’s critical conditions (critical pressure, critical temperature, and critical volume), allow for the use of generalized charts or equations to predict the thermodynamic and transport properties of one fluid based on data from another. This principle, developed from van der Waals’s work, simplifies calculations by eliminating material-specific constants, enabling universal correlations for properties like the compressibility factor.
Principle of measurement – It is the scientific base of a measurement. Examples are (i) the thermoelectric effect applied to the measurement of temperature, (ii) the Josephson effect applied to the measurement of electric potential difference, (iii) the Doppler effect applied to the measurement of velocity, and (iv) the Raman effect applied to the measurement of the wave number of molecular vibrations.
Principle of optimality – It is also known as Bellman’s principle of optimality. It states that an optimal solution to a problem contains within it, optimal solutions to all of its subproblems. This principle is fundamental to the dynamic programming approach, where a complex problem is broken down into smaller, overlapping subproblems, each of which is solved optimally to construct the overall optimal solution.
Print – It is the part of the core used to locate and support. It is part of a pattern to form area in mould for same purpose. It is the part of mold and part in core box for the same purpose.
Print back – It means that after the surface of a mould is dusted with graphite facing, the pattern is replaced, rapped into position and again removed.
Printed board drawing sets consist of those drawings which define the configuration of printed wiring or printed circuit boards and assemblies. They establish requirements for assembly and test. A typical drawing set includes an assembly drawing, schematic diagram, master drawing, and may include an artwork master. It specifies the engineering requirements for assembly and includes (i) identification of parts, materials, and processes required for the assembly, (ii) electrical insulating requirements, (iii) reference designations, terminal identification, polarity symbols, and index marks, (iv) control dimensions, (v) jumper wires, (vi) requirements for identification and traceability marking, spot bonding, conformal coating, and masking, part mounting, support, and assembly, cleanliness, part orientation and polarity, electrostatic discharge protection, special solder plug, lead forming, and electric testing , (vii) solder mask, and (ix) reference document identification. A master drawing provides the complete engineering description of a printed board which includes (i) all dimensions and tolerances necessary to establish board size and shape, mounting hole locations, cutouts, and hole sizes, etc., (ii) un-dimensioned holes located by the conductor pattern and at theoretical grid intersections, (iii) minimum annular rings for conductor patterns surrounding terminal holes to control both hole-to-terminal relationship and registration between layers, (iv) minimum conductor width, spacings, and distance to board edges, (v) registration marks to assure proper alignment of patterns and marking masters on two-sided and multilayer boards, (vi) definition of the cross section details of multilayer boards, (vii) dielectrics thickness between layers of multilayer boards, (viii) raw materials and plating requirements, (ix) etch back allowances, (x) reference designation marking, (xi) maximum rated voltage, (xi) identification and traceability marking requirements, (xii) test points, (xiii) test tab requirements, (xiv) the shape and arrangement of conductor or circuit patterns, hole locations, and printed marking requirements, (xv) critical pattern features which can affect circuit performance, (xvi) views of conductor or circuit patterns and printed marking requirements, (xvii) applicable process specification, and (xviii) process allowances used in preparing the artwork master. Artwork master is a precision scale pattern on stable base material used to produce printed boards within the accuracy established by the master drawings and to establish and control the configuration of the conductor or circuit and marking patterns when these details are not included in the master drawings.
Printed circuit – It is an electronic circuit consisting of thin strips of a conducting material such as copper, which have been etched from a layer fixed to a flat insulating sheet called a printed circuit board, and to which integrated circuits and other components are attached.
Printed circuit board (PCB) – It is a laminated sandwich structure of conductive and insulating layers, each with a pattern of traces, planes and other features (similar to wires on a flat surface) etched from one or more sheet layers of copper laminated onto or between sheet layers of a non-conductive substrate. Printed circuit boards are used to connect or ‘wire’ components to one another an electronic circuit. Electrical components can be fixed to conductive pads on the outer layers, normally by soldering, which both electrically connects and mechanically fastens the components to the board. Another manufacturing process adds vias, metal-lined drilled holes which enable electrical inter-connections between conductive layers, to boards with more than a single side. Printed circuit boards are used in nearly all electronic products today.
Printed wiring boards – They are like the printed circuit boards are very important for all electronic devices. One important feature of a printed wiring board is its high component density. Hence, a good number of packaging techniques are used which include chip on board, chip scale packaging, and ball grid array. Also, the components of the surface mount have a miniature size. This offers maximum density of the component, coupled with providing some maintenance for the thermal, electrical, and the signal integrity of the device. One important factor in printed wiring board’s interconnection design is the speed of operation of electronic devices. Also, the speed of signal proportion has an inverse proportion to the dielectric constant) of the printed wiring board’s substrate material. Increasing the gates number, as well as clock rates will lead to an increase in the consumption of power. Printed wiring boards are poor heat conductors. Hence, proper care is needed when using the methods for the dissipation of the heat that which has been generated by the printed wiring board’s power consumption. Metal slugs, as well as conductive planes, thermal vias, heat sinks in printed wiring boards, are good techniques.
Printer – It is a device which makes permanent human readable images and text from computer data.
Printing – It is a method in which a carrier material is saturated with an etchant and pressed against the surface of the sample. The etchant reacts with one of the phases, and substances form that react with the carrier material, leaving behind a life-size image. It is used for exposing particular elements, e.g., sulphur (sulphur prints).
Printing back – It means that to dust the cavity with Plumbago and reprint pattern. It smoothes the cavity surface by filling voids.
Prior appropriation – It is a law doctrine under which users who can demonstrate earlier use of a particular resource are given right which take precedence over all future users of the resource.
Prior austenite grain – It refers to the original, large grains of the high-temperature austenite phase in a steel, which are no longer present at room temperature after it has cooled and transformed. These pre-existing grain boundaries (PAGBs) are important since they dictate the size and characteristics of subsequent microstructures, such as martensite, and influence mechanical properties like strength, toughness, and fatigue life. Techniques like the McQuaid-Ehn test and etching of pro-eutectoid phases are used to reveal these prior austenite grain boundaries for analysis.
Prior-beta grain size – It the size of beta grains established during the most recent beta-field excursion. Grains can be distorted by subsequent sub-transus deformation. Beta grain boundaries can be obscured by a superimposed alpha-beta microstructure and detectable only by special techniques.
Priori assumptions – These refer to the initial conditions or restrictions applied in a model before data analysis, which are crucial for estimating the model and can influence the validity of the results. These assumptions are tested for correctness to ensure that the model’s conclusions are reliable.
Priori expectations – These refer to the anticipated outcomes of coefficient estimates in a cost model, which align with economic theory, indicating that changes in output and input prices affect total costs in a predictable manner.
Priori-knowledge – It refers to information obtained from prior experience and pretests of a process, which includes rough estimates of process gain and dominant time constants. This knowledge is utilized for assessing model quality by comparing model gains and settling times with these estimates.
Priori restrictions – These refer to constraints imposed on empirical data distributions based on prior knowledge or assumptions, including moment restrictions that depend on unknown parameters.
Prior particle boundary (PPB) – It is one of the common defects in a powder metallurgy superalloy, and it is a layer of tiny and continuous second phase omentum (apron like structure) on the original powder surface during heating process in milling and hot isostatic pressing or hot extrusion. This layer of precipitates may hinder the diffusion and connection between powder particles, resulting in a weak interface, damaging the alloy structure, and endangering the tensile, impact, and other mechanical properties of a powder metallurgy superalloy.
Priority – It is the concept that the person first using a resource has a better right to it than those commencing their use later. An appropriator is normally assigned a ‘priority date’. However, the date is not significant in and of itself, but only in relation to the dates assigned other resource users from the same source of the resource. Priority is only important when the quantity of available resource is not sufficient to meet the needs of all those having a right to use the resource.
Priority activity – It is a task or project given precedence over others, meaning it is scheduled and executed first because of its high urgency and / or importance to project or organizational goals. This prioritization ensures that limited resources are focused on critical items, such as urgent repairs, key project milestones, or strategic initiatives, to maintain efficiency and achieve objectives, especially in dynamic environments or when faced with resource constraints.
Prior microstructure – It refers to the initial structure of steel before heat treatment, which influences substantially the outcomes of hardening processes and the selection of process parameters such as austenitizing temperature and holding time.
Prism – It is a transparent optical element whose entrance and exit apertures are polished plane faces. Using refraction and / or internal reflection, prisms are used to change the direction of propagation of monochromatic light and to disperse polychromatic light into its component wavelengths.
Prism beam expander – It is an optical device which uses a system of multiple prisms, or a prism array, to increase the diameter of a collimated light beam, particularly for one-dimensional expansion. Unlike traditional telescopic beam expanders, prism expanders operate without a focal point within the system, avoiding high power density issues. They are valued for their compactness, alignment simplicity, ability to correct beam ellipticity, and minimal aberration, making them ideal for applications like laser spectroscopy, microscopy, and beam shaping.
Prism dispersion – It refers to the process where a prism separates white light into its constituent colours by bending each wavelength at a different angle because of the material’s frequency-dependent refractive index. This phenomenon is crucial for optical components and systems, such as spectrometers, laser systems, and optical fiber communication, where it is used to analyze or manipulate light based on its wavelength.
Pristine-M process technology -This technology is for the drying of the low rank coals. It is a technology for converting raw low rank coal into a cleaner burning more efficient fuel. It addresses the need for a low moisture coal which is economical to transport, stable in transportation and does not reabsorb moisture. It is a low-cost coal de-watering technology which has succeeded in drying coal and stabilizing it cheaply using volatile matter (VM) released by the feed raw coal. It reduces the moisture content of low-rank coals, while also stabilizing and sealing the treated coals to prevent moisture re-absorptions and spontaneous combustion. The process also increases the calorific value (CV) of the low-rank coals to values which are comparable with the bituminous coals.
PRMS – PRMS is Petroleum Resources Management System (PRMS), which was approved by the Society of Petroleum Engineers (SPE) Board and endorsed by the World Petroleum Council (WPC), the American Association of Petroleum Geologists (AAPG), the Society of Petroleum Evaluation Engineers (SPEE), and the Society of Exploration Geophysicists (SEG).
Proactive approach – It involves actively anticipating and preventing potential problems, failures, or defects in a system or product before they occur, rather than waiting for them to manifest. This is achieved through early identification of potential threats and risks, careful planning, and the implementation of preventative measures to improve quality, stability, and safety, hence reducing the negative impact of future issues.
Probabilistic safety assessment – It is a mathematical tool for calculating the risk of certain problems or accidents occurring at a plant. It is the methodology to probabilistically estimate risks. Fault tree analysis and event tree analysis are integral techniques for probabilistic safety assessment.
Probability – It is a term used in statistic. It is concerning events and numerical descriptions of how likely they are to occur. The probability of an event is a number between 0 and 1, the larger the probability, the more likely an event is to occur. This number is frequently expressed as a percentage (%), ranging from 0 % to 100 %. A simple example is the tossing of a fair (unbiased) coin. Since the coin is fair, the two outcomes (‘head’ and ‘tails’) are both equally probable, the probability of ‘heads’ equals the probability of ‘tails’, and since no other outcomes are possible, the probability of either ‘heads’ or ‘tails’ is 1/2 (which can also be written as 0.5 or 50 %).
Probability density functions – It is synonymous with probability distributions, knowing the probability which a random variable takes on certain values, judgements can be made as to how likely or unlikely were the observed values. In general, observing an unlikely outcome tends to support the notion that chance is not acting alone. By posing alternative hypotheses to explain the generation of data, an analyst can conduct hypothesis tests to determine which of two competing hypotheses best supports the observed data. Probability density function of an absolutely continuous random variable, is a function whose value at any given sample (or point) in the sample space (the set of possible values taken by the random variable) can be interpreted as providing a relative likelihood that the value of the random variable would be equal to that sample. Probability density function is the probability per unit length, in other words. While the absolute likelihood for a continuous random variable to take on any particular value is 0 (since there is an infinite set of possible values to begin with), the value of the probability density function at two different samples can be used to infer, in any particular draw of the random variable, how much more likely it is that the random variable is to be close to one sample compared to the other sample. More precisely, the probability density function is used to specify the probability of the random variable falling within a particular range of values, as opposed to taking on any one value. This probability is given by the integral of this variable’s probability density function over that range, i.e., it is given by the area under the density function but above the horizontal axis and between the lowest and greatest values of the range. The probability density function is nonnegative everywhere, and the area under the entire curve is equal to 1.
Probability distribution – It is a statistical function which describes the probability of different possible values of a variable. It is a statistical function that describes all the possible values and probabilities for a random variable within a given range. Probability distributions are frequently depicted using graphs or probability tables. Probability distribution function gives the probabilities of occurrence of possible events for an experiment. It is a mathematical description of a random phenomenon in terms of its sample space and the probabilities of events (subsets of the sample space). For example, if ‘X’ is used to denote the outcome of a coin toss (the experiment), then the probability distribution of ‘X’ is to take the value 0.5 (1 in 2 or 1/2) for ‘X’ = heads, and 0.5 for ‘X’ = tails (assuming that the coin is fair). normally, probability distributions are used to compare the relative occurrence of several different random values. Probability distributions can be defined in different ways and for discrete or for continuous variables. Distributions with special properties or for especially important applications are given specific names.
Probability function – It describes the likelihood of different outcomes for a random variable, either assigning a probability to each specific value in a discrete set (a probability mass function, PMF) or providing a density for a range of values in a continuous system (a probability density function, PDF). These functions assign non-negative values which sum to 1 (for PMF) or integrate to 1 (for PDF), ensuring the total probability of all possible outcomes is certainty.
Probability of detection – It is defined as the fraction of nominal discontinuity sizes expected to be found given their existence. The concept of probability of detection is used in different industry sectors to establish the capability of an inspection to detect flaws. This is normally expressed as a probability of detection curve, which relates the likelihood of detection to a characteristic parameter of the flaw, normally its size.
Probability of false alarm – In period (frequency) search, it is defined as the probability which a value resulting from a time-series analysis based on some form of periodogram is caused by noise. For example, the probability of false alarm is the probability of having an alarm, for a given material, in a given location if there is no mine in that location.
Probability sample – It is a type of sample for which one can specify the probability that any member of the population is selected into it. This type of sample enables generalization of the study results to a known population.
Probable error – It is a statistical measure used in error analysis and measurement to define the expected range for a true value, indicating that there is a 50 % probability which a given error (or a quantity like a correlation coefficient) fall within that range (true value +/- probable error). It helps in assessing the reliability of measurements by providing confidence limits, where a smaller probable error signifies higher precision. It is related to the standard error, which is now normally used in modern analysis.
Probable Mineral reserves – Probable Mineral reserves are economically mineable part of indicated or in some cases, a Measured Mineral resource.
Probable Ore reserve – A Probable Ore reserve is the economically mineable part of an Indicated, and in some circumstances, a Measured Mineral resource. The confidence in the Modifying factors applying to a Probable Ore reserve is lower than that applying to a Proved Ore reserve.
Probable reserves – It consists of valuable mineralization which is not sampled enough to accurately estimate the terms of tonnage and grade. It is also called ‘indicated reserve’.
Probe – It is a physical device / instrument which is used to detect defects in the finished product restricting its utilization or making it unfit for use. Probe is used for sorting out the defective products from prime products.
Probe gas – It is a tracer gas which issues from a fine orifice so as to impinge on a restricted test arca.
Probe ion – It is an ionic species intentionally produced by an ion source and directed onto the sample surface at a known incident angle and a known energy.
Probe signal – It refers to a specific signal or stimulus used to test, measure, or analyze a system or component, or it can be a signal which is probed (monitored) from within a device to observe its internal state without disrupting the system’s overall functionality. The term’s precise meaning varies depending on the engineering discipline, from testing electronic circuits with oscilloscope probes to geological surveys with physical probes.
Probe test – It is a leak test in which the tracer gas is applied by means of a probe so that the arca covered by the tracer gas is localized. This enables the individual leaks to be located.
Probe tip – It is a fine, frequently atomically sharp instrument at the end of a cantilever which interacts with a sample’s surface to perform scanning probe microscopy (SPM). Its geometry and material properties dictate the resolution and quality of nano-scale images and measurements of forces, chemical bonding, and surface topography generated by scanning probe microscopy devices like atomic force microscopes (AFMs). The tip’s ability to ‘feel’ the surface allows it to map out its physical features and characteristics at a molecular or atomic level.
Problem – It consists of the difference between an actual situation and a desired situation. The problem is defined as any event or situation, unforeseen, unwanted in an organization, a project, or a job which needs to be addressed and resolved before it becomes too complex.
Problem formulation – It is the critical first step of the design process, involving defining, scoping, and structuring a real-world issue into a clear, solvable problem by articulating objectives, identifying constraints, specifying requirements, and collecting necessary data. A well-formulated problem ensures the correct issue is addressed, leading to efficient, effective, and sustainable solutions.
Procedure – It is a step-by-step description of how to do a task, job, or activity properly.
Procedure qualification – It is the demonstration which welds made by a specific procedure can meet prescribed standards.
Procedure qualification record (PQR) – It is a document providing the actual welding variables used to produce an acceptable test weld and the results of tests conducted on the weld to qualify a welding procedure specification.
Process – It is the physical system which is to be controlled or measured. A process consists of a set of interrelated or interacting activities, which transforms inputs into outputs. These activities need allocation of resources such as people and materials. All the organizational processes are required to be aligned with the objectives, scope, and complexity of the organization, and are to be designed to add value to the organization. The assessment of the process effectiveness and efficiency can be carried out through internal or external reviews. In a process, inputs and intended outputs can be tangible (such as equipment, materials or components) or intangible (such as energy, or information). Outputs can also be unintended, such as wastes or pollution generation. Every process has customers and other interested parties (who can be either internal or external to the organization), with needs and expectations about the process, who define the required output of the process. It is also a grouping of basic operational elements used in welding, cutting, adhesive bonding, or thermal spraying.
Process air – It is compressed air used directly in a manufacturing or industrial process as a raw material, contacting the product itself and needing high quality, and purity, depending on the specific application. Unlike plant air or instrument air, it is to meet specific quality standards, frequently needing drying, and filtration for oil to prevent contamination.
Process annealing – It is a heat treatment used to soften metal for further cold working. In ferrous sheet and wire industries, it is heating to a temperature close to but below the lower limit of the transformation range and subsequently cooling for working. In the non-ferrous industries, it is heating above the recrystallization temperatures at a time and temperature sufficient to permit the desired subsequent cold working.
Process approach – The application of a system of processes within the organization, together with the identification and interactions of these processes, and their management to produce the desired outcome, can be referred to as process approach. The purpose of the process approach is to improve the organizational effectiveness and efficiency in achieving its defined objectives. Hence, a process approach means that the organization manages its operations as a system of processes and not as departments, or people, or products. This system is used to gather data to provide information about process performance, which is then to be analyzed to determine if there is any need for corrective action or improvement. The process approach includes establishing the organizational processes to operate as an integrated and complete system. This include (i) the management system integrates processes and measures to meet objectives, (ii) processes define interrelated activities and checks, to deliver intended outputs, and (iii) detailed planning and controls can be defined and documented as needed, depending on the organizational context.
Process assurance – It is the system of planned, ongoing activities used to evaluate, monitor, and improve the quality and consistency of processes within an organization, ultimately ensuring that they meet defined requirements, standards, and goals while minimizing risks. The goal of process assurance is to demonstrate that the processes function as intended and consistently produce high-quality results, leading to increased business benefit and customer satisfaction.
Process audit – This audit is the testing of a process or a series of processes in production and administration. It is used in particular where specific key processes take place. It is first and foremost required to establish whether the production is under control and whether the actions / control are appropriately matched to the requirements of the quality criteria and quality evidence. These process competence investigations are frequently part of customer requirements. The process audit is to be used as early as possible, similar to the sample or first-sample verification.
Process average – It is a level at which a process is performing on an average.
Process behaviour – It describes how a process acts and performs over time, including its patterns, consistency, and variations. It focuses on the dynamic aspects of a process, such as its execution and performance, and involves assessing process variability to determine if a process is stable and predictable or if it shows exceptional variation.
Process behaviour over time – A succession of parts emanating from a process under statistical control show variability in their measurements because of a constant set of common causes. These variable measurements tend to collect into a predictable pattern of variation which can be easily described by a few simple statistical measures namely, a mean, a standard deviation, and a frequency distribution. These measures stand as a model which predicts how the process is going to behave if subject only to a constant set of common causes.
Process breakdown – It refers to the process of dividing a complex process into smaller, more manageable components to better understand, analyze, and plan it. Alternatively, it also means the failure of a process or system, similar to a ‘breakdown’ of machinery or a plan, indicating that it is no longer functioning as required.
Process capability – It is a statistical measure of the inherent process variability of a given characteristic. A person can use a process-capability study to assess the ability of a process to meet specifications. During a quality improvement initiative, such as Six Sigma, a capability estimate is typically got at the start and end of the study to reflect the level of improvement which has occurred. Several capability estimates are in widespread use. The first is potential capability (Cp) and actual capability during production (Cpk) are process capability estimates. Cp and Cpk show how capable a process is of meeting its specification limits, used with continuous data. They are valuable tools for evaluating initial and ongoing capability of parts and processes. The second is sigma which is a capability estimate typically used with attribute data (i.e., with defect rates).
Process capability index (Cpk) – It is a statistical tool which measures how well a process can consistently produce output within specified limits and how centered the process is on its target. It is calculated as the minimum of the distances from the process mean to the upper and lower specification limits, divided by three standard deviations. A higher process capability index value indicates a more capable process which meets customer specifications.
Process chart – It is a visual, symbolic diagram which shows the sequence of steps, operations, and decision points in a process or workflow. It uses standard shapes connected by lines to represent activities, show relationships, and clarify a complex workflow, aiding in understanding, analysis, and improvement.
Process computer system (PCS) – It performs functions such as process control to optimize plant operation, and information services to operators. Process models to apply higher level control strategies are integrated in process computer system with special plant measurement systems.
Process control – It is a system used in modern manufacturing which uses the principles of control theory and physical industrial control systems to monitor, control and optimize continuous industrial production processes using control algorithms. This ensures that the industrial machines run smoothly and safely in factories and efficiently use energy to transform raw materials into high-quality finished products with reliable consistency while reducing energy waste and economic costs, something which cannot be achieved purely by human manual control.
Process control panel – It is a flat, frequently vertical, area where control or monitoring instruments are displayed or it is an enclosed unit which is the part of a system that users can access. These panels are designed to monitor and control process parameter levels such as temperature, flow, current, and pressure from the field instruments which are connected to it. These panels are used in a wide variety of industries.
Process control software – The most widely adopted user friendly approach is the fill-in-the-forms or table-driven process control languages (PCL). Popular process control languages include function block diagrams, ladder logic, and programmable logic. The core of these languages is a number of basic function blocks or software modules, such as analog in, digital in, analog out, digital out, proportional–integral–derivative, summer, splitter, etc. Using a module is analogous to calling a sub-routine in conventional ‘Fortran’ or ‘C’ programmes. In general, each module contains one or more inputs and an output. The programming involves commuting outputs of blocks to inputs of other blocks through the graphical-user interface. Users are needed to fill in templates to indicate the sources of input values, the destinations of output values, and the parameters for forms / tables prepared for the modules. The source and destination blanks can specify process I/O (input / output) channels and tag names when appropriate. To connect modules, some systems need filling in the tag names of modules originating or receiving data. User specified fields include special functions, selectors (minimum or maximum), comparators (less than or equal to), and timers (activation delays).
Process control systems – These systems refer to the monitoring, controlling, and regulating of industrial processes using a variety of technologies and approaches. The objective of process control systems is to ensure that the process runs within the specified parameters, yields a consistent and high-quality result, and performs as efficiently as feasible.
Process cycle time – It is the total duration to complete one entire process or production cycle, from the moment work begins until the final product or service is finished. It measures the real-world time a task, service, or production takes, encompassing not only hands-on and machine time but also any waiting times between steps. By tracking cycle time, organizations can measure operational efficiency, identify bottlenecks, and streamline their processes to reduce costs and improve performance.
Process description – It is a narrative explanation detailing a series of events or actions in a logical, chronological order to achieve a specific goal, such as explaining how to make something or how something happens. It typically includes an introduction, a general overview of the process, and a step-by-step breakdown. Key elements include clear, specific vocabulary, chronological linking words (like ‘first’ or ‘then’), and frequently visual aids like flowcharts to help the reader understand the sequence and components involved.
Process design – It is the choice and sequencing of units for desired physical and / or chemical transformation of materials. Process design is central to the process engineering, and it can be considered to be the summit of that field, bringing together all of the field’s components. Process design can be the design of new facilities or it can be the modification or expansion of existing facilities. The design starts at a conceptual level and ultimately ends in the form of fabrication and construction plans. Process design is distinct from equipment design, which is closer in spirit to the design of unit operations. Processes often include many unit operations. In case of operation management, process design is the process of creating and improving systems which convert inputs into outputs. Process design involves understanding how work is done within an organization and then designing and implementing ways to improve it. There are several types of process designs, but all share some standard features. Process designs is required to take into account the resources needed to complete the process, the desired output of the process, and any constraints on the process. In addition, process designs is to be flexible enough to accommodate changes in inputs or outputs.
Process development – It is the systematic design, refinement, and optimization of processes, particularly for manufacturing, to produce products efficiently, cost-effectively, and to high standards of quality. It involves identifying and analyzing existing methods, developing new or improved production systems, and frequently includes stages like design, prototyping, mapping processes to find inefficiencies, optimizing operations, and ensuring the process can be scaled up to meet demand. The goal is to achieve better productivity, lower costs, improved product quality, and regulatory compliance.
Process diagrams – These are the most effective way of communicating information about a process. A process diagram consists of activities, events, and gateways, which a sequence flow puts in a flow sequence. Activities, events, and gateways are summarized under the term flow object. A process diagram is the key to the development and management of an industrial production process. It is a diagram of the steps in a process and their sequence. It constitutes a simplified sketch which uses symbols to identify instruments and vessels and to describe the primary flow path through a unit.
Process disturbance – It is an unplanned, external event or change in a variable which alters a process’s normal operation, affecting the flow of heat or material, and potentially making the process unstable and unpredictable. These disturbances are typically outside the control of the process or its operators, leading to variations in the output which differ from expected or predictable patterns.
Process-driven design – It is a design approach in which the manufacturing process plan or method of assembly is developed prior to developing the product design.
Process driver – It is a characteristic or variable which influences the operation, performance, or outcomes of a process, system, or activity. These drivers determine the necessary conditions for efficiency, impact key results, and enable changes in the process or entity they affect. Examples include the rate of heat release in a chemical reaction (process engineering), economic factors like commodity prices (process economics), or software components interacting with hardware (computing).
Processed data – It is raw, unprocessed data which has been transformed, organized, and analyzed into a meaningful and usable format, frequently called information. This transformation involves several steps like cleaning, filtering, sorting, and aggregation to derive insights or fulfill specific purposes, such as creating reports, dashboards, or actionable business intelligence from complex datasets.
Processed image – It is a digital or analog image which has undergone image processing techniques (such as noise reduction, contrast enhancement, or object recognition) to improve its quality, extract useful information, or transform it into a more meaningful representation. The output of image processing can be an altered image, a set of extracted characteristics, or a report based on the analysis of the image. Processed image is an image which has undergone specific signal-processing techniques to improve its quality or extract intrinsic details, resulting in either an improved visual representation or analytical output.
Process efficiency – It refers to how well an organizational process transforms inputs (time, resources, effort) into valuable outputs, measuring the ratio of output to input for a given process. An efficient process needs minimal resources and time to produce a result, leading to less waste, rework, and costs, ultimately impacting profitability.
Process engineer – A process engineer is a professional who designs, optimizes, and manages industrial processes to transform raw materials into finished products efficiently and effectively. Process engineers use principles of physics, chemistry, and mathematics to analyze manufacturing steps, troubleshoot issues, control production, ensure safety, and reduce costs and waste. Process engineers work in several industries, including manufacturing, metallurgical, and chemicals, ensuring products meet quality standards and that the production system runs smoothly and sustainably.
Process engineering – It is the design, optimization, and management of industrial processes to transform raw materials and energy into finished products efficiently and safely. It involves applying principles of science and mathematics to control variables like temperature, pressure, and chemical composition to improve performance, yield, and quality while ensuring cost-effectiveness and sustainability. Process engineers work across different industries, using data analysis to monitor performance and implement improvements in manufacturing, metallurgical, energy, and more.
Process equipment – It refers to machines, devices, and systems used in industrial settings to transform raw materials into finished products or to modify materials through mechanical or chemical processes. These tools perform necessary functions like mixing, heating, cooling, separation, and drying in different industries. Common examples include pumps, valves, heat exchangers, reactors, and distillation columns, which are important for ensuring processes are efficient, safe, and high-quality.
Process factors – It refer to the elements or variables which substantially influence the execution and outcome of a process. These factors can be internal to the process itself or external, and they can impact efficiency, effectiveness, and overall success.
Process failure – It takes place, when a process does not produce the expected or correct outcome, either through a complete breakdown or a degraded performance that deviates from specified requirements. This failure can be caused by a specific fault (a defect in the system or a mistake in the process) which leads to an error (an incorrect state or incorrect operation), ultimately resulting in a failure which makes the delivered service incorrect or unusable.
Process failure mode and effects analysis (PFMEA) – It is part of the larger failure mode and effects analysis (FMEA) family. It is a risk management tool which assesses potential failures of a process. It identifies possible failure points in a process, documents their causes, and effects, suggests corrective actions and action to mitigate risks, and reduces the likelihood of those causes and effects. Iti s a risk assessment methodology which is used to identify and mitigate potential failures in manufacturing and business processes. It is a proactive approach to quality control and process improvement, helping organizations prevent defects and improve operational efficiency.
Process flow chart – It is also known as a process map. It is a visual representation of a process, using standardized symbols and shapes to show the sequence of steps and decision points within that process. It helps to clarify, analyze, and improve how a process is executed.
Process flow diagram – It is a type of flow-chart which demonstrates the relationships between major components of a plant unit. It is very frequently used in process engineering, though its concepts are sometimes applied to other processes as well. It is used to document a process, improve a process, or model a new process. Depending on its use and content, it can also be called a process flow chart, flow-sheet, schematic flow diagram, macro flow-chart, top-down flow-chart, system flow diagram, or system diagram. Process flow diagram primarily defines (i) a schematic representation of the sequence of all relevant operations occurring during a process and includes information considered desirable for analysis, (ii) the process presenting events which occur to the material(s) to convert the feed-stock(s) to the specified products, and (iii) an operation occurring when an object (or material) is intentionally changed in any of its physical or chemical characteristics, is assembled or dis-assembled from another object or is arranged or prepared for another operation, transportation, inspection or storage. Process flow diagram normally includes (i) plant design basis indicating feed-stock, product and main
streams flow rates and operating conditions, (ii) identify the scope of the process, (iii) shows graphically the arrangement of major equipment, process lines, and main control loops, and (iv) shows needed utilities which are used continuously in the process.
Process gap – It refers to the discrepancy between a current process’s performance and a desired or optimal state. It is the difference between ‘where one is’ and ‘where one wants to be’ regarding a specific process, highlighting areas needing improvement. Essentially, it is identifying inefficiencies, bottlenecks, or outdated practices within a process that prevent it from achieving its intended outcome or meeting desired standards.
Process heat – It is the thermal energy needed in industrial operations to produce or alter manufactured goods. This heat is applied to materials to cause physical or chemical changes, such as melting, drying, or chemical reactions. Common sources for generating process heat include burning fossil fuels or using electrical resistance, though low-carbon alternatives like concentrated solar power are increasingly being explored.
Process improvement – It refers to the practice of finding ways to make existing processes faster, more accurate, more efficient, and more reliable. This practice is to be considered an ongoing exercise rather than a one-time action.
Processing chamber – It is a sealed, controlled environment where materials or substrates are subjected to different treatments, like deposition, etching, thermal processing, or additive manufacturing, to prevent contamination and ensure process stability. It isolates the processing area from the outside atmosphere and allows for precise control over environmental factors such as temperature, pressure, gas composition, and flow rate to achieve desired material properties.
Processing cost – It refers to the total expenses incurred to produce mass-produced, identical units through a series of sequential production stages, such as direct materials, direct labour, and production overhead. These costs are assigned to each unit by dividing the total costs of a process by the number of units produced, providing an average cost per unit for pricing and inventory valuation.
Processing plant – It is an industrial facility which transforms raw materials into finished products using chemical, mechanical, or other specialized methods. These plants are important across different sectors and contain equipment like reactors, distillation columns, furnaces, and heat exchangers etc. to carry out their operations efficiently and safely.
Processing technology – It encompasses the methods, tools, and equipment used to design, control, and optimize industrial or organizational processes to transform raw materials into finished products or to deliver services. It involves the application of scientific and engineering principles, frequently including automation and control systems, to manage operations efficiently, ensure product quality, maintain safety, and meet organizational objectives.
Processing time – It is the duration it takes for a system, task, or procedure to be completed. It is a measure of efficiency, indicating how quickly something can be handled, which is important in contexts like computer science, manufacturing, and operation. For example, in e-commerce, it is the time from when an order is placed until it is ready for shipping.
Processing window – It is the range of processing conditions, such as stock (melt) temperature, pressure, shear rate, and so on, within which a particular grade of plastic can be fabricated with optimal or acceptable properties by a particular fabricating process, such as extrusion, injection moulding, sheet moulding, and so on. The processing window for a particular plastic can vary significantly with design of the part and the mould, with the fabricating machinery used, and with the severity of the end-use stresses.
Process instruction – It is a set of specific guidelines or a detailed, step-by-step document explaining how to perform a specific task, activity, or set of actions within a larger process to achieve a desired outcome. These instructions are important for quality management, ensuring consistency, and guiding employees or systems through tasks effectively. They are a form of work instruction and can be found in different fields, including engineering, manufacturing, and computing.
Process instruments – These are devices which measure, monitor, and control key physical variables (like flow, temperature, pressure, and level) in an industrial process to ensure safety, efficiency, and product quality. They serve as the ‘eyes’ and ‘hands’ of an industrial operation, providing data to operators or automated systems to maintain optimal conditions and achieve desired outcomes.
Process intensification – It is a design approach in process engineering which makes processes operate in much smaller equipment for the same performance, leading to smaller, cleaner, safer, and more energy-efficient technologies. It involves integrating steps and using advanced equipment like microchannel reactors and spinning disk reactors to improve transport processes and reduce energy and capital costs.
Process interruption – It is the act of temporarily stopping a primary task to attend to another task or event, with the intention of resuming the original process later.
Process life cycle assessment – It is a systematic and standardized methodology for evaluating the environmental impacts of a product, process, or service throughout its entire life cycle, from raw material extraction and processing to manufacturing, distribution, use, and final disposal or recycling. It involves defining goals and scope, conducting an inventory of inputs and outputs (data collection), assessing the impacts of these flows, and finally interpreting the results to make informed decisions and promote sustainability.
Process line – It is a sequential system where operations or equipment are arranged in a connected series to produce a product or perform a service, ensuring an uninterrupted flow of materials and synchronized stages. It features functionally independent phases in a specific order, with work progressing through workstations to complete tasks. Common in manufacturing, process lines aim for efficiency by specializing tasks and standardizing the production path.
Process management – It is a concept which is based on the observation that each product that an organization provides to the market is the outcome of a number of activities performed. Processes are the key instrument for the organization of these activities and for improving the understanding of their interrelationships. The organization can reach its goals and objectives in an efficient and effective manner only if people and other organizational resources play together well. Processes are an important concept for facilitating this effective collaboration.
Process management systems – These are the systems which integrate all the functions required to manage a technological process system. Process management systems provide a common database for all functions and allow the integration of analog loop control, discrete logic control, data acquisition, data management, statistical calculations, and reporting. Communications and inter-connection are also by means of soft wiring, that is, by configuration and programming instead of physical hard wiring.
Process map – It is a visual diagram which shows the steps, tasks, and flow of a process from beginning to end, frequently using standard symbols and arrows to show the sequence and connections. Organizations use process maps as a powerful tool for planning, communicating workflows, identifying bottlenecks and inefficiencies, and improving overall performance by making complex processes clear and understandable for all stakeholders
Process measurements – The most commonly measured process variables are temperatures, flows, pressures, levels, and composition, when appropriate, other physical properties are also measured. The selection of the proper instrumentation for a particular application is dependent on factors such as the type and nature of the fluid or solid involved, relevant process conditions, rangeability, accuracy, and repeatability needed, response time, installed cost, and maintainability and reliability.
Process medium – It is a substance or system which serves as a vehicle or facilitator for the transfer of energy, information, or materials within a process. For example, in physics, a material medium like air or water transmits energy (like sound or heat), while in communication, media (such as email or video conferencing) act as the trail for sending messages. In industrial processes, a medium can be a liquid that helps separate materials or a chemical substance used to enable a reaction.
Process metallurgy – It is the science and technology of winning metals from their ores and purifying metals. It is sometimes referred to as chemical metallurgy. Its two chief branches are extractive metallurgy and refining.
Process model – It is an ‘algorithm to predict the behaviour of an open or closed system’. It allows predictive control and operator assistance, off-line process optimization, improved understanding of the underlying physical phenomena, and the on-line estimation of parameters which cannot be determined directly through measurements. The term process model refers to the deterministic models based on physical and thermodynamic relationships, and hence excludes purely statistical approaches.
Process models – Process models are processes of the same nature which are classified together into a model. Hence, a process model is a description of a process at the type level. Since the process model is at the type level, a process is a representation of it. The same process model is used repeatedly for the development of several applications and hence, has several representations. One possible use of a process model is to prescribe how things are to be / can be done in contrast to the process itself which is really what happens. A process model is roughly an anticipation of what the process is going to look like. What the process is going to be is determined during actual system development. The goals of a process model are to be is (i) descriptive which includes tracking of what actually happens during a process and taking the point of view of an external observer who looks at the way a process has been performed and determining the improvements which are to be made to make it perform more effectively or efficiently, (ii) prescriptive which includes defining the desired processes and how they are to be / can be performed and establishing rules, guidelines, and behaviour patterns which, if followed, lead to the desired process performance (they can range from strict enforcement to flexible guidance), and (iii) explanatory which includes (i) providing explanations about the rationale of processes, (ii) exploring and evaluating the several possible courses of action based on rational arguments, (iii) establishing of an explicit link between processes and the requirements which the model needs to fulfill, and (iv) pre-defining of the points at which data can be extracted for reporting purposes.
Process monitoring – It is the continuous observation, supervision, and assessment of a process to ensure it functions as intended, identifies deviations, and enables timely interventions to maintain efficiency, quality, and desired performance standards. It involves collecting real-time data on key performance indicators (KPIs) and process variables to support decision-making, improve reliability, and facilitate manual or infrequent adjustments rather than continuous automated control.
Process noise – It refers to unpredictable, random variations or disturbances within a system or process which deviate from its expected or modelled behaviour. It represents the inherent uncertainty and inaccuracy in the dynamics of a system itself, in contrast to sensor noise which affects measurements. In fields like control systems and Kalman filtering, process noise is treated as a random variable which accounts for factors like unmodelled accelerations, unknown changes, and other disturbances which cause the actual state of the system to differ from its predicted state.
Process optimization – It is the discipline of adjusting a process so as to make the best or most effective use of some specified set of parameters without violating some constraint. Common goals are minimizing cost and maximizing throughput and / or efficiency. Process optimization is one of the major quantitative tools in industrial decision making. When optimizing a process, the goal is to maximize one or more of the process specifications, while keeping all others within their constraints. This can be done by using a process mining tool, discovering the critical activities and bottlenecks, and acting only on them.
Process owner – Process owner is an individual accountable for managing, improving, and ensuring the success of a specific organizational process, from design and implementation to ongoing performance and alignment with organizational goals. They act as a single point of accountability, defining key performance indicators (KPIs), documenting the process, and collaborating with teams to optimize its efficiency and effectiveness. The process owner is not necessarily the person performing the tasks but is responsible for the overall outcomes and continuous improvement of the process.
Process parameter – It is a measurable factor, setting, or condition within a manufacturing or organizational process which affects its output and quality. These variables, such as temperature, pressure, speed, or time, are controlled and monitored to ensure the process runs efficiently and consistently, producing a desired outcome within acceptable quality standards.
Process path – It is the continuous sequence of intermediate states a system passes through from an initial state to a final state during a process. It describes how a system changes, including the intermediate conditions and decisions made, as opposed to the initial and final states themselves, which define the system’s condition at specific points. The path is important since some aspects of a process, known as path functions, depend on the specific route taken to reach a given state, whereas others, state functions, do not.
Process performance – It refers to the evaluation of a process based on factors such as yield, consumption of resources like raw materials, and utility requirements like heating and cooling.
Process performance measurement – It is the process of collecting, analyzing, and reporting information regarding the process performance.
Process piping – It is an interconnected network of pipes, valves, and fittings which transports fluids (like liquids, gases, and chemicals) within an industrial facility to manufacture products or generate power. It is integral to the process plant, forming the backbone for moving materials between different equipment and storage tanks. These systems must adhere to strict design codes and are built with materials chosen for their ability to handle specific fluid conditions.
Process plant – It is a large industrial facility where raw materials are transformed into new products through a series of chemical, physical, or mechanical processes. These facilities use specialized equipment, such as reactors, furnaces, and distillation columns etc., to convert resources into valuable finished or intermediate products for several industries.
Process pressure – It is the force per unit area within a system during an ongoing operation. It is important for controlling and maintaining process performance and safety. It is a key variable which is to be monitored and controlled, since variations in process pressure can affect the system’s integrity and overall efficiency, for example, by impacting factors like energy efficiency, product yields, or the product quality.
Process route – It is a structured plan which defines the sequence of operations, resources, and time needed to produce a product or execute a workflow, aiming for efficiency, quality, and cost-effectiveness. In manufacturing, it details steps, workstations, and materials, while in organization or information technology (IT) contexts, it describes the steps, participants, and logic of an organizational process or workflow. The concept emphasizes a logical flow, with variations possible based on resources and product needs.
Process safety – It is a disciplined framework for managing the integrity of operating systems and processes which operates under hazardous conditions and handle hazardous materials. It relies on good design principles, engineering, and operating and maintenance practices. It deals with the prevention and control of undesirable events which have the potential to release hazardous materials and energy to the surrounding environment. It is normally accepted that ‘process safety’ is about preventing incidents which, while having a low likelihood of their occurrence, are associated with severe potential consequences. Process safety is needed for the protection of people and property from episodic and catastrophic incidents which can result from unplanned or unexpected deviations in process conditions.
Process sequence – It is a specific order of steps, actions, or events which are followed to achieve a particular outcome, whether in manufacturing, project management, or computing. The goal of establishing a process sequence is to create a structured, predictable, and efficient method which ensures reliable and consistent results by defining the logical relationships and dependencies between each step.
Process simulation – It is used for the design, development, analysis, and optimization of technical process of simulation of technological processes, environmental systems, power stations, complex manufacturing operations, biological processes, and similar technical functions. Process simulation is a model-based representation of chemical, physical, biological, and other technical processes and unit operations in software. Basic prerequisites for the model are chemical and physical properties of pure components and mixtures, of reactions, and of mathematical models which, in combination, allow the calculation of process properties by the software.
Process sludge – It is the semi-solid, thick residue generated during different industrial processes, very frequently wastewater and sewage treatment plants. It consists of a mixture of water, organic compounds inorganic solids, nutrients (like nitrogen and phosphorus), micro-organisms, and potentially harmful contaminants such as heavy metals. The specific composition and characteristics of the sludge vary based on its origin, such as primary sludge from sedimentation or secondary / activated sludge from biological treatment stages.
Process specification – It is a document or technical specification which details the requirements, procedures, and steps necessary to transform inputs into outputs within a system or manufacturing process. It serves as a clear guide for creating high-quality, consistent data, reducing ambiguity, and ensuring tasks are performed as intended. This documentation is a normal component of requirements for software and product development, ensuring regulatory compliance, quality control, and maintaining standards.
Process stack – It is also known as a smokestack or flue-gas stack. It is a vertical structure designed to discharge flue gases (containing emissions from industrial processes, combustion, or other chemical processes) to the outside air at a height which allows for dispersion, reducing ground-level concentrations to permissible limits. These structures utilize the ‘stack effect’, or chimney effect, driven by buoyancy from temperature and density differences, to draw the gases upward and outward.
Process stage – It is a discrete phase, period, or set of steps within a larger process, defining a specific function or activity which is to be completed to move the process forward. These stages act as mile-stones, with one stage needing completion before the next can begin, helping to organize and guide work through a lifecycle, whether it is a metallurgical or chemical process, an organizational work-flow, or a computer programme’s operation.
Process steam – Process steam is a popular mode of conveying energy and can come into contact with the final process or product. It is the steam used for industrial purposes other than for producing power. It is the general term used for steam which is used in process applications such as a source of energy for process heating, process cooling, pressure control and mechanical drives among others. It is the steam used in various industrial processes mainly to utilize its heat and moisture. The most common operational end uses employed for process steam include stripping, fractionation, process heating and cooling, quenching, dilution, vacuum draw, pressure regulation, injection and source of process water etc.
Process stream – It is a continuous flow of materials, energy, or data through a system, frequently encountered in different types of processes. In short, it represents the dynamic progression of inputs and outputs within a system, continuously processed in real-time rather than in discrete batches.
Process structure – It refers to the organization and inter-relationship of activities, steps, or elements which form a complete process, defining how a process operates, flows, and is managed. It establishes the process hierarchy, boundaries, and connections between its parts to achieve a specific outcome, ensuring efficiency, consistency, and traceability. Different types of process structures exist across several fields, with each tailored to its specific context and goals.
Process technology – It encompasses the systems, tools, and techniques used to transform raw materials into finished products or deliver services. It involves the design, optimization, and control of industrial processes across different sectors, aiming to improve efficiency, productivity, and quality. Essentially, it is about applying technology to the methods used in production and service delivery.
Process time – It refers to the duration needed for a specific procedure, task, or algorithm to complete from beginning to end. It is a critical metric for evaluating efficiency and performance in different fields, helping to identify bottlenecks and areas for improvement.
Process transmitter – The process transmitter is a pressure transmitter with a pressure range which can be set within a predefined pressure range (turndown). It is mainly used in technological processes, since in this application area it is necessary to adjust every single measuring point to a multitude of specific requirements which are to be individually set by the operator on site. The process transmitters have very high measurement accuracy within the entire pressure range. In addition, the pressure range, the zero point and further parameters can normally be set individually. For this purpose, several process transmitters have both digital display and additional operating elements and extensive operating software directly within the instrument.
Process validation – It is the documented evidence and objective proof, based on collected and evaluated data, which a specific manufacturing process consistently produces a product meeting predetermined specifications and quality attributes. It establishes a high degree of assurance that the process is reliable and capable of delivering quality products throughout its lifecycle, an important requirement to ensure product safety and efficacy.
Process variable (PV) – It is the parameter whose quantity is to be measured in a process. Examples of parameters are pressure, level, temperature, flow, electrical conductivity, pH, position, and speed etc.
Process wastes – These are solid wastes which are generated during the production processes. These also includes wastes from the laboratories attached to the production processes. Examples of process wastes are slag, dust, sludge, scrap, refractories, scale, muck, and debris etc.
Process water – It is the water which comes into contact with raw material, product, by-product, or waste. All process water from the manufacturing plant is required to receive extensive treatment and be in compliance with all local regulatory requirements. Process water is used to keep the refinery product streams and equipment cool. By cooling the water in large cooling towers and re-circulating it, the quantity of fresh water needed is minimized.
Process window index (PWI) – It is a statistical measure used in manufacturing, particularly in electronics assembly, to quantify how well a thermal profile (like a reflow profile) fits within the defined process window. It essentially measures the robustness of the process by indicating how close the profile is to the edge of the acceptable tolerance limits. A lower process window index indicates a more robust process, meaning it can better handle variations and still produce acceptable results.
Process yield – It is the ratio of the quantity of acceptable output to the total quantity of output in a manufacturing or production process, frequently expressed as a percentage. It serves as a key performance indicator of process efficiency, showing the proportion of defect-free units which pass a compliance check compared to the total units produced. A higher process yield indicates a more efficient, cost-effective, and high-quality process.
Process zone – It normally refers to a specific area where a particular type of activity occurs, leading to unique characteristics or modifications within that zone.
Procurement – It is the process of locating and agreeing to terms and purchasing goods, services, or other works from an external source, frequently with the use of a tendering or competitive bidding process. The term can also refer to a contractual obligation to ‘procure’, i.e., to ‘ensure’ that something is done.
Procurement control drawing – It provides criteria for performance, acceptance, and identification of supplier items by disclosing the engineering design characteristics required normally for control of interfaces and to ensure repeatability of performance. It is prepared to specify criteria for (i) purchased items, (ii) alterations to purchased items, (iii) selection from purchased items, (iv) development and qualification of new items, and (v) item identification. It includes (i) performance requirements to ensure that performance characteristics critical to the intended application are met, (ii) envelope dimensions to ensure physical interchangeability in using assemblies, (iii) interface characteristics to ensure functional interchangeability in using assemblies, (iv) qualification requirements necessary to verify that performance requirements and functional inter-changeability, (v) identification requirements including marking, instructions, lot serialization, etc., (vi) procurement data, (vii) acceptance criteria, and (viii) to identify any variations between items.
Procurement managers – They are also called purchase managers. They are professionals responsible for sourcing, negotiating with, and managing suppliers to purchase the best quality goods and services for the organization at competitive prices. Their key duties include developing buying strategies, managing budgets and inventory, ensuring timely and cost-effective delivery, minimizing supply chain risks, and ensuring that all purchasing activities comply with company policies and regulations.
Producer gas – It is a fuel gas containing carbon mono-oxide, hydrogen, and nitrogen, produced by passing a limited supply of air or a mixture of air and steam through a bed of hot solid fuel like coal, coke, or biomass in a gasifier. It serves as a low-cost industrial fuel, though its low calorific value is because of a high nitrogen content.
Product – It is the collection of organizational capabilities valuable to a defined customer segment. A product can be just software and data. A product encompasses not only tangible physical goods but also services, experiences, and even ideas which can be marketed and sold. Products principally serve external customers. In case of mining terminology, product is defined as the products of the project which can be bought, sold, or used, including electricity, heat, hydrocarbons, hydrogen, minerals, and water. It is noted that with some projects, such as for renewables, the products (electricity, heat etc.) are different from the sources (wind, solar irradiation etc.). In other projects, the products and sources can be similar e.g., in petroleum projects both the sources and products are oil and / or gas, although the fluid state and properties can change from reservoir to surface conditions.
Product analysis – It is a comprehensive evaluation process that examines a product’s features, functionality, and overall performance to understand its strengths, weaknesses, and potential for improvement. It involves analyzing user behaviour, market trends, and competitor strategies to make informed decisions about product development and improvement. Ultimately, product analysis aims to optimize a product’s design, features, and user experience for ensuring its success in the market.
Product audit – It is the product audit can be considered as a shortened version of the process audit. In the product audit, the quality of products or components is tested at a specific part of the product production. At the same time, the documentation used up to this point and, if applicable, the fabrication and testing equipment used are also tested. A product audit is carried out to (i) establish the quality level of the products to be supplied, (ii) verify that the products to be supplied meet the specified quality standard, (iii) establish the quality level of the products delivered to testing stations, (iv) determine the capability of testing stations to identify quality defects and to make quality decisions, (v) assess the quality-control procedures, (vi) assess whether controlled production is taking place, and (vii) determine the reproducibility of the test results. The concept of the product audit is also to determine whether the necessary means and procedures are available to produce and assess a quality product.
Product category – It is a group of similar products which share common features, characteristics, or purposes, helping organizations and customers organize offerings and find what they need. This organizational strategy simplifies inventory management, streamlines marketing efforts, and enhances the customer experience by making products easier to find and understand within a market.
Product certification – It a procedure by which a third party gives written assurance that a product, or process conforms to specified requirements. The product certification authorities normally permit the use of a mark on the product to demonstrate that the product meets a defined set of requirements, such as certain properties, safety, fitness for use and / or specific interchangeability characteristics which are normally specified in a standard. The mark is normally found on the product or its packaging. It also carries a reference to the number of the relevant product standard against which the product is certified. Ideally, a product certification mark is to demonstrate to the customer that a product meets the normally accepted standard for that product. Product certification helps the customer to choose products which meet the requirements of the specified standard, are suitable for the purpose, and are safe from hazards to life and property. Product certification gives an organized purchaser greater confidence in the integrity of the product, saves unnecessary product inspection, and provides a convenient basis for concluding contracts. For the producer, product certification streamlines the production process and introduces a quality assurance system for ensuring conformity of the product to the standard. Product certification enhances the marketability of products.
Product criterion – It is a specific, measurable standard or characteristic which a product is to meet to be considered acceptable, effective, or viable for its intended purpose. These criteria serve as a guide for design, development, and evaluation, ensuring the product meets user needs, technical requirements, and market standards, such as performance attributes, quality, durability, and security.
Product data management (PDM) – It is a system using software to centrally organize, store, and control all technical product-related data, such as CAD (computer aided design) models, drawings, bills of materials (BOMs), specifications, and manufacturing instructions. Its main goal is to provide design and engineering teams with timely, accurate, and secure access to this data, hence improving collaboration, reducing errors, improving efficiency, and streamlining product development processes.
Product design – It describes the process of imagining, creating, and iterating products which solve users’ problems or address specific needs in a given market. It is the process of creating new products for organizations to sell to their customers. It involves the generation and development of ideas through a systematic process that leads to the creation of innovative products. Hence, it is a major aspect of new product development.
Product design process – It consists of a sequence of steps which are followed by a product team to develop a design solution. It consists of a series of design tasks which follow a product from start to finish i.e., from idea to the final product ready to be commercially available to the target user.
Product design specification (PDS) – It is a detailed description of the intended and unintended uses which a product is going to be put to, a list of any special features required or desired, and a detailed list of the functional requirements with qualitative or quantitative goals and limits for each. It is also known engineering design specification.
Product development – It is the end-to-end process of bringing a new product to market or improving an existing one, encompassing all stages from initial concept and research to design, manufacturing, testing, and final launch. Its main goal is to create a product which meets customer needs and desires, solves problems, and satisfies market demands, ultimately driving organizational growth through innovation and improved customer value.
Product development process – It is the structured series of stages an organization follows to bring a product from an initial concept to market availability and continuous improvement. It involves steps like idea generation, market research, product definition, prototyping, testing, and commercialization to ensure the final product meets market demands and user needs.
Product distribution – It is the process of making products available and accessible to target customers and organizational users, involving the logistics of getting goods from producers to customers through different channels, such as wholesalers, retailers, or direct-to-customer sales. It encompasses transportation, warehousing, and inventory management to ensure products are in the right place, at the right time, and in the right quantities.
Product diversification strategy – It is a form of organizational development. Organizations which implement the strategy can diversify their product range by modifying existing products or adding new products to the range. The strategy provides opportunities for the organization to grow the revenues by increasing sales to existing customers or entering new markets.
Product documentation – It consists of all of the documentation, whether on paper or in digital form, which defines the steps in designing the product and specifies the steps needed for its manufacture. These include product design specification, quality function deployment (QFD) matrices, concept selection results, geometric dimensioning and tolerancing schemes, detail drawings, bill of materials, and manufacturing process plans.
Product failure – It occurs when a product fails to achieve its intended objectives, meet performance standards, or satisfy customer and organizational expectations, leading to symptoms like declining sales, inability to cover costs, withdrawal from the market, or malfunctioning. This failure can stem from the product’s inability to solve the right problems, poor market fit, high costs, poor quality, or ineffective marketing and distribution.
Product footprint – It is the part of the product which touches any part of the conveyor, including wheels, belts, or rollers.
Product integrity – In the manufacturing sense, it is the absence of voids, pores, cracks, and harmful inclusions.
Production area – It is a dedicated physical space where raw materials or supplies are transformed into a final product or service, a process frequently optimized for efficiency and quality. This space, also known as a production floor or shop floor, includes the machinery and the environment necessary for manufacturing, ranging from large factory floors to specialized areas like processing plants. Production areas are to adhere to strict design and operating standards, including proper ventilation, easy-to-clean surfaces, and segregated zones for different processes, to prevent contamination and ensure environmental control.
Production casting – It is a manufacturing process where liquid material, very frequently molten metal, is poured into a mould to create a solid object with a specific, complex shape. After the material solidifies within the mould, the finished casting is removed for post-processing. This technique is widely used to produce intricate and often large components, and it is particularly useful for mass production and for making shapes which are difficult or uneconomical to produce by other methods.
Production certificate – It is a formal approval from statutory agency, which permits an organization to manufacture and supply products s per a previously approved design and quality system, or an approved standard. It serves as proof that the production process is going to consistently create products which meet the specified requirements, ensuring safety, quality, and performance standards are maintained over time and in serial production.
Production drawing – It also referred to as working drawing. A component or part drawing is termed as a production drawing, if it facilitates its manufacture. It is an authorized document to produce the component on the shop floor. It furnishes all the dimensions, limits, and special finishing processes such as heat treatment, honing, griding, lapping, and surface finish etc., to guide the technician on the shop floor in producing the component. The title also mentions the material used for the product, and number of parts needed for the assembled unit etc. Since a technician normally makes one component at a time, it is advisable to prepare the production drawing of each component on a separate sheet. However, in some cases the drawings of related components can be given on the same sheet.
Production foundry – It is highly mechanized foundry for manufacturing large quantities of repetitive castings.
Production level – It refers to the quantity of goods or services an organization produces over a given time period. It can also refer to the capacity of a system to produce, indicating the minimum and maximum output possible within operational limits.
Production method – It is the specific set of techniques, processes, and steps used by an organization to efficiently transform raw materials or other inputs into finished goods or services for consumption. These methods can range from large-scale, continuous flow systems to smaller, customized job processes, and they are selected based on factors like product type, market demand, available resources, and cost considerations.
Production performance – It measures how effectively an organization converts resources like materials, labour, and capital into goods and services, focusing on the speed, efficiency, quality, and cost of the production process. It involves monitoring actual output against standard output to assess resource utilization, identify waste, and determine if production goals are being met within desired quality and time parameters.
Production planning and control (PPC) – It is part of the production system of the organization and responsible for the smooth coordinated production in the organization. It is a tool available to the plant management to achieve the stated objectives of meeting the production targets in an efficient manner. It balances the available capacities with the product requirements to meet the market demands. With production planning and control plans, the production of the plant becomes systematic and becomes focal point for all the departments for the achievement of the departmental targets and objectives. Production planning and control carries out planning of production to establish the route of production and to make schedules which ensures optimum utilization of materials, production facilities and workforce. By close monitoring, it also ensures that the plant operation is carried out as per the plans and the results are obtained in terms of quantity, quality, delivery schedule and cost of production. The main objectives of production planning and control are (i) to prepare and monitor the production schedules, (ii) to carry out planning for the procurement of raw materials, fuels, utilities, and other materials, (iii) to plan product dispatch along with the marketing or sales department, (iv) to facilitate in the attainment of maximum utilization of resources, (v) to plan production of products of the needed quality, (vi) to plan with minimum manufacturing cycle time, (vii) to plan maintenance of optimum inventory levels at various production stages, (viii) to integrate maintenance schedules of the shop with production plan, (ix) to plan production with maximum flexibility in operations, (x) to achieve coordination between process, work-force and other connected departments, (xi) to collect various data and analyze it for monitoring and decision making, (xii) to act as a custodian for the data of production system, (xiii) to identify bottlenecks in fulfillment of production plans, and (xiv) to facilitate cost and budget controls and to achieve the goals at minimum cost.
Production planning and scheduling – It is the strategic and tactical process of organizing resources to meet manufacturing demands. Production planning focuses on the ‘what’ and ‘how much’ to produce, setting overall output levels, and determining necessary materials, labour, and equipment to meet demand forecasts. Production scheduling then converts these plans into a detailed, operational timetable, specifying ‘when’ and ‘where’ each production activity occurs by allocating resources and sequencing tasks to optimize production flow and timely delivery.
Production plant – It is an industrial facility, frequently a complex consisting of several buildings filled with machinery, where workers manufacture items or operate machines which process input raw materials into products and by-products.
Production process – It is a process which uses resources, such as raw materials, labour, capital, utilities, power, and equipment, and turns them into finished goods or services for the customers. The goal of the production process is not only to produce but to do so efficiently. The goods or services are to be delivered to customers as quickly as possible. The production process is to be effective since it impacts the organizational performance.
Production rate – It refers to the quantity of goods or services produced within a specific time frame. It essentially measures the efficiency of a production process, indicating how much output can be generated over a given period. It can also be expressed as the time it takes to produce a single unit of output.
Production scheduling – It is the process which determines the production schedule, identifies long-term raw material requirements, determines the pack-out schedule for end products and determines product available for sale. The information generated or modified by the production scheduling function includes (i) the production schedule, (ii) the actual production against the planned production, (iii) the production capacity and resource availability, and (iv) current order status.
Production scrap – It is unusable material which results from a manufacturing process since does not meet quality specifications or is a byproduct of the production process, such as metal shavings or excess raw materials. While it has little to no value as a finished product, it frequently retains some basic material value and can be recycled, reprocessed, or sold. Factors like poor quality control, inefficient processes, or incorrect material usage can lead to scrap, and minimizing it is crucial for profitability.
Production semi – It refers to semi-finished goods used in production, which are materials or components which have been partially processed but need further manufacturing steps to become a final product.
Production shop – It is also known as a job shop. It is a manufacturing facility characterized by low volume, high variety production of custom or specialized items. These shops use general-purpose machines and skilled workers to produce goods based on unique customer specifications and often with specific timelines and budgets.
Production strategy – It is a long-term plan which details how an organization creates its goods and services to meet market demand and achieve corporate goals. It involves making strategic decisions about production methods, technology, resource allocation, factory location, and the overall design of the production system to gain a competitive advantage. An effective production strategy aligns with the company’s overall objectives, considering factors like cost, quality, and efficiency to ensure profitability and market competitiveness.
Production systems – Production systems are systems which are used to produce goods or services. These systems frequently involve multiple steps or processes which are to be completed in order to produce the final product.
Production volume – It refers to the total quantity of goods or services produced by a facility or a piece of equipment within a given period. It is a critical metric for manufacturing plants, service providers, and any operation that seeks to quantify output. Overall production volume can be measured in units, batches, tons, or any other relevant quantity which reflects the production capacity and output of the operation. Production volume a key metric used to assess output, track performance, and plan for maintenance.
Production waste – It encompasses material remnants and inefficiencies discarded during manufacturing, including physical materials not used in the final product, by-products which the producer has no further use for, and any process steps which do not add value to the end product. It is any unwanted output of an industrial or production process, whether solid, liquid, or gaseous, which can range from scrap metal and chemicals to wasted time and resources.
Production welding – It one of several welding carried out during manufacturing before final delivery to the purchaser. This includes joint welding of casting and finishing welding.
Productive capacity – It is the maximum quantity of goods and services which can be produced by an organization within a given timeframe, using available resources, technology, and skills. It is determined by the interplay of productive resources (like capital, labour, and infrastructure), entrepreneurial capabilities (skills and knowledge), and production linkages (connections between organizations).
Productivity – It means the efficiency of production of goods or services expressed by some measure. Measurements of productivity are frequently expressed as a ratio of an aggregate output to single input or an aggregate input used in a production process, i.e. unit output per unit of resource input, typically over a specific period of time. The most common example is the (aggregate) labour productivity measure, one example of which is the output per worker. There are several different definitions of productivity (including those which are not defined as ratios of output to input) and the choice among them depends on the purpose of the productivity measurement and data availability. The key source of difference between different productivity measures is also normally related (directly or indirectly) to how the outputs and the inputs are aggregated to get such a ratio-type measure of productivity. Productivity is a crucial factor in the production performance of processes and organizations. Increasing productivity can help organizations to be more profitable.
Productivity index – It is a metric which measures the efficiency of a system. It is the ratio of current productivity to a base period’s productivity. In general, it quantifies the relationship between output and input, showing how well inputs are converted into outputs over time or under different conditions.
Product launch – It is an organizational planned, coordinated, and systematic effort to introduce a new or updated product to the market, make it available for purchase, and generate customer interest, awareness, and sales. It involves a series of stages, from pre-launch planning and marketing campaigns to the actual market entry and post-launch feedback, needing collaboration across multiple departments like product development, sales, and marketing to ensure a successful entry and build brand recognition and market momentum.
Product liability – It is a legal term which describes the action whereby an injured party (plaintiff) seeks to recover damages for personal injuries or property loss from a producer and / or seller (defendant) when the plaintiff alleges that a defective product or design caused the injury or loss.
Product lifecycle management (PLM) – It is the process of managing the entire lifecycle of a product from its inception through the engineering, design, and manufacture, as well as the service and disposal of manufactured products. Product lifecycle management integrates people, data, processes, and business systems and provides a product information backbone for organizations and their extended enterprises.
Product mix – It refers to all the products an organization offers to its customers. It includes different categories of products, each with multiple options. Some products can be closely related, while others serve different needs. A well-balanced product mix helps an organization attract a wider audience, meet diverse customer preferences, and increase sales.
Product output – It is the final result of a production or creation process, representing the finished goods, services, or data generated from different inputs, such as raw materials, labour, or energy. It can be measured in units produced, monetary value, or information generated, and it serves as the value-added element which is sold to customers, used by other organizations, or consumed by end-users.
Product performance factors – These are the criteria and metrics used to evaluate how well a product meets its intended purpose and achieves its goals, encompassing functionality, reliability, customer satisfaction, and commercial success. These factors provide insights into a product’s effectiveness and its contribution to the overall objectives of the organization.
Product / process performance factors – These play varying roles and are important system factors / variables which play in influencing product / process performance. These factors are classified into four categories namely (i) signal factors which can be adjusted by the user to attain the target performance, (ii) control factors which are the product / process design parameters whose values are to be determined during the design process, (iii) noise factors which are either inherently uncontrollable or impractical to control because of technological / economic reasons, and (iv) scaling / leveling factors which are special cases of control factors that can be easily adjusted to achieve a desired functional relationship between a signal factor and the output response.
Product profile – It is a strategic planning document which defines the desired characteristics, features, and performance of a future product. It acts as a roadmap, specifying the intended use, target population, and key attributes like safety and efficacy to guide and align research, development, and regulatory activities across different teams and stakeholders, ultimately aiming to meet specific unmet needs and achieve commercial success.
Product qualification – It is a rigorous process of testing, documenting, and validating that a product and its manufacturing processes meet specified performance, quality, functionality, and reliability standards before mass production. It provides documented evidence that the product is fit for its intended use, ensuring confidence in its behaviour and preventing potential failures, maintenance costs, and negative customer experiences in the long term.
Product quality – It refers to the characteristics, features, and attributes of a product which determine its ability to meet customer expectations and perform its intended function. Quality encompasses different aspects, such as reliability, durability, performance, safety, and conformance to specifications. Achieving and maintaining high product quality involves rigorous quality control measures, adherence to standards and regulations, continuous improvement initiatives, and feedback from customers and stakeholders. Product quality refers to the intrinsic attributes and characteristics of a product which determine its overall excellence and ability to meet customer needs and expectations. High-quality products are those which excel in different dimensions of quality, such as functionality, durability, usability, accessibility, and conformance. High-quality products conform to established quality standards and validation specifications. They consistently meet predetermined quality criteria.
Product quality management – The goal of the product quality management is to minimize the mistakes of the operators and the break-down of equipments and machines so as to have stable processes, hence, ensuring that the customers remain happy with the product performance and reorder the products. For this the organization is to put a relentless focus on product quality. Product quality management includes the following four major components. They are (i) quality planning, (ii) quality control, (iii) quality assurance, and (iv) quality improvement.
Product reworking – It is the process of disassembling, altering, or correcting a product to fix defects, failures, or non-conformities, making it meet original specifications or customer needs. This can involve tasks like repair, replacement of parts, reassembly, or changes to packaging or branding, frequently performed after a product has failed inspection or been damaged during transit or use.
Product sampling – It is a marketing strategy where organizations provide potential customers with free samples of their products, aiming to encourage them to try the product and potentially make a purchase. It is a way to let the product ‘speak for itself. and build trust and awareness before a purchase is made.
Products of combustion – These are the gases, vapours, and solids resulting from the combustion of fuel. These are the end product when fuels, such as hydrocarbons, remain after the process of combustion. Hence, these are released and scattered into the atmosphere. Products of combustion include heat, light, chemical species, pollutants, mechanical work, and plasma.
Product specification – It is a detailed document which acts as a blueprint for a product or feature, outlining its requirements, features, functionality, technical aspects, and performance criteria to guide the design and development process. It serves as a central source of truth, ensuring that all stakeholders have a clear understanding of the product’s goals, target users, and intended outcomes, ultimately aiming for a high-quality product which meets customer needs and organizational objectives.
Product technology – It refers to the scientific and engineering knowledge, methods, and tools used to design, develop, manufacture, and improve products. It encompasses the technology embedded within a product itself (operational technology or OT) and the technologies used in its production. Essentially, it is the practical application of scientific principles to create functional and marketable items.
Product yield – In a manufacturing process, product yield is the usable output quantity divided by the input quantity at every stage of the production process.
Pro-eutectoid – In the context of iron-carbon alloys, pro-eutectoid refers to a phase (either ferrite or cementite) which forms from austenite during cooling before the temperature reaches the eutectoid point (723 deg C). This means it appears before the eutectoid reaction, where austenite transforms into ferrite and cementite.
Pro-eutectoid carbide – It consists of primary crystals of cementite formed directly in ferrous alloys from the decomposition of austenite exclusive of that cementite resulting from the eutectoid reaction.
Pro-eutectoid ferrite – It consists of primary crystals of ferrite formed directly in ferrous alloys from the decomposition of austenite exclusive of that ferrite resulting from the eutectoid reaction.
Pro-eutectoid phase – It consists of particles of a phase in ferrous alloys which precipitate during cooling after austenitizing but before the eutectoid transformation takes place.
Profile – It is a term normally used to refer to a cross-sectional view of an object or material. In civil engineering, a profile consists of a plotted line which indicates grades and distances (and typically depths of cut and / or elevations of fill) for excavation and grading work. Constructors of roadways, railways (and similar works) normally chart the profile along the centre line. Profile is also the anchor pattern on a surface produced by abrasive blasting or acid treatment. It is also a wrought product which is long in relation to its cross-sectional dimensions, which is of a form other than that of sheet, plate, rod, bar, tube, wire, or foil. In flat steels, profile is made up of the measurements of crown and wedge. Crown is the thickness in the centre as compared to the average thickness at the edges of the steel strip or sheet. Wedge is a measure of the thickness at one edge as opposed to the other edge. Both are normally expressed as absolute dimensions or as relative dimensions. As an example, the steel piece can have a crown of 0.05 millimeters (the centre of the steel is 0.05 millimeters thicker than the edges), or the steel piece can have 2 % crown (the centre of the steel piece is 2 % thicker than the edges). It is typically desirable to have some crown in the steel piece since it causes the steel piece to tend to pull to the centre of the rolling mill, and thus the rolling takes place with higher stability.
Profile, class 1 hollow extruded – It is a hollow extruded profile, the void of which is round and 25 millimeters or more in diameter and whose weight is equally distributed on opposite sides of two or more equally spaced axes.
Profile, class 2 hollow extruded – It is a hollow extruded profile other than class 1, which does not exceed a 125 millimeters diameter circumscribing circle and has a single void of not less than 10 millimeters diameter or 70 square millimeters area.
Profile, class 3 hollow extrude – It is a hollow extruded profile other than class 1 or class 2.
Profile, cold-finished. A profile brought to final dimensions by cold working to obtain improved surface finish and dimensional tolerances.
Profile, cold-finished extruded – It is a profile produced by cold finishing an extruded profile.
Profile, cold-finished rolled – It is a profile produced by cold finishing a rolled profile.
Profile (contour) rolling – In ring rolling, it is a process used to produce seamless rolled rings with a predesigned shape on the outside or the inside diameter, requiring less volume of material and less machining to produce finished parts.
Profile cutting – It is a precision cutting process which is used to shape materials, particularly metals, into complex geometries or specific outlines. It involves using specialized cutting machines, frequently CNC (computer numerical control) controlled, to follow a pre-defined path or profile, resulting in accurate and intricate cuts. This technique is widely used in various industries for manufacturing parts, components, and structures with custom shapes and designs. Profile cutting aims to create parts with complex shapes or specific outlines, often exceeding the capabilities of simpler cutting methods.
Profile, drawn – It is a profile brought to final dimensions by drawing through a die.
Profile, extruded – It is a profile produced by hot extruding.
Profile, flute hollow – It is a hollow profile having plain inside surfaces and outside surfaces which comprise regular, longitudinal, concave corrugations with sharp cusps between corrugations.
Profile, helical extruded – It is an extruded profile twisted along its length.
Profile, hollow – It is a profile in which any part of its cross section completely encloses a void.
Profile, lip hollow – It is a hollow profile of normally circular cross-section and nominally uniform wall thickness with one hollow or solid protuberance or lip parallel to the longitudinal axis. It is used mainly for heat-exchange purposes.
Profile, pinion hollow – It is a hollow profile with regularly spaced, longitudinal serrations outside, and round inside, used mainly for making small gears.
Profiler – It an instrument to measure wind speed and direction at different elevations above the ground. It is also a surface analysis instrument which is also called a profilometer. It is also any of several types of machine tools for reproducing shapes in metal or other materials from a master form.
Profile, rolled – It is a profile produced by hot rolling.
Profile, semi-hollow – It is a profile in which any part of its cross section is a partially enclosed void the area of which is substantially higher than the square of the width of the gap. The ratio of the area of the void to the square of the gap is dependent on the class of semi-hollow profile, the alloy, and the gap width.
Profile, solid – It is a profile other than hollow or semi-hollow.
Profile, stepped extruded -It is an extruded profile with a cross section which changes abruptly in area at intervals along its length.
Profile, streamline hollow – It is a hollow profile with a cross section of tear-drop shape.
Profile, structural – It is a profile in certain standard alloys, tempers, sizes, and sections, such as angles, channels, H sections, I-beams, tees, and zees, commonly used for structural purposes.
Profile, tapered extruded – It is an extruded profile with a cross section which changes continuously in area along its length or a specified portion thereof.
Profile tolerance – It defines a uniform boundary around a surface within which the elements of the surface must lie. Profile is a complex tolerance which simultaneously controls a feature’s form, size, orientation, and sometimes location. Profile is a three-dimensional tolerance that applies in all directions regardless of the drawing view where the tolerance is specified. It is usually used on parts with complex outer shape and a constant cross-section like extrusions.
Profiling – It is an operation which produces an irregular contour on a work-piece, for which a tracer or template controlled duplicating equipment normally is used.
Profit and loss projection – It presents the plan of revenues and expenses of the organization over the specific accounting period. Profit and loss projection follows the same pattern as the profit and loss statement. However, it reflects the data about the future.
Profit and loss statement – It is the income statement of an organization detailing revenues minus total costs to give total profit.
Programmable automation – It refers to a type of automation where the sequence of operations can be easily changed by reprogramming the system. This allows for flexibility in production, enabling the system to handle different product designs or configurations within the same production line. This automation system is used for a changeable sequence of operation and configuration of the machines using electronic controls. However, non-trivial programming effort can be needed to reprogram the machine or sequence of operations. Investment on programmable equipment is less, as production process is not changed frequently. The system consists of equipment designed to accommodate a specific class of product changes. This type of automation is typically used in batch processes where job variety is low and product volume is medium to high, and sometimes in mass production also.
Programmable automation controller (PAC) – It is a term which is loosely used to describe any type of automation controller that incorporates higher-level instructions. The systems are used in industrial control systems (ICS) for machinery in a wide range of industries, including those involved in critical infrastructure.
Programmable control units – These units operate in conjunction with personal computers and make possible the convenient storage of workpiece- and material-specific treatment parameters in a database. In such an automated system, any significant variations from production charges can easily be evaluated and effectively compensated.
Programmable logic controller – It is an industrial computer which has been ruggedized and adapted for the control of manufacturing processes, such as assembly lines, machines, robotic devices, or any activity which needs high reliability, ease of programming, and process fault diagnosis. Programmable logic controller can range from small modular devices with tens of inputs and outputs (I/O), in a housing integral with the processor, to large rack-mounted modular devices with thousands of I/O, and which are frequently networked to other programmable logic controller and Supervisory Control and Data Acquisition (SCADA) systems. They can be designed for several arrangements of digital and analog I/O, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact.
Programmable real-time unit (PRU) – It is a small processor core which is tightly integrated with an input / output subsystem, offering low-latency control of input / output pins.
Programming language – It is a formalism for human-readable instructions to a computer.
Progression – It is the constant dimension between adjacent stations in a progressive die.
Progressing cavity pump – It is a type of positive displacement pump. It and is also known as a progressive cavity pump, progg cavity pump, eccentric screw pump or cavity pump. It transfers fluid by means of the progress, through the pump, of a sequence of small, fixed shape, discrete cavities, as its rotor is turned. This leads to the volumetric flow rate being proportional to the rotation rate (bidirectionally) and to low levels of shearing being applied to the pumped fluid. These pumps have application in fluid metering and pumping of viscous or shear-sensitive materials. The cavities taper down toward their ends and overlap. As one cavity is diminished, another increases, the net flow amount has minimal variation as the total displacement is equal. This design results in a flow with little to no pulse.
Progressive aging – It consists of aging by increasing the temperature in steps or continuously during the aging cycle.
Progressive collapse – It is the process where a primary structural element fails, resulting in the failure of adjoining structural elements, which in turn causes further structural failure. Progressive collapses can be accidental, as the result of design deficiencies, fire, unintentional overload, material failure or natural phenomenon. They can also be induced deliberately as a demolition method, specifically that of building implosion, or caused by acts of terrorism or war.
Progressive die – It is a die with two or more stations arranged in line for performing two or more operations on a part. It is one operation is normally performed at each station.
Progressive die casting – It also known as continuous die stamping. It is a metal forming process which uses a series of specialized workstations within a single die to transform a continuous strip of metal into a finished part with each press stroke. This process is highly automated and efficient for producing complex, precision metal parts in large volumes.
Progressive dipping – It is the act of dipping steel more than once in cleaning solutions and molten zinc metal in order to produce a coating which covers the entire surface of the steel. It is normally done when the steel article / fabrication is too large to fit entirely into the pot in one dip.
Progressive forming – It is the sequential forming at consecutive stations with a single die or separate dies.
Progressive rate coil spring – It consists of a coil spring with a variable rate, normally achieved by having unequal distance between turns so that as the spring is compressed one or more coils rests against its neighbour.
Progressive solidification – It is also known as parallel solidification. It is solidification which starts at the walls of the casting and progresses perpendicularly from that surface. Majority of metals and alloy shrink as the material changes from a liquid state to a solid state. Hence, if liquid material is not available to compensate for this shrinkage a shrinkage defect form. When progressive solidification dominates over directional solidification a shrinkage defect form.
Progress report – It is a document which provides updates on the status of an ongoing project, outlining tasks completed, those in progress, and future assignments. Its main purpose is to keep stakeholders informed about a project’s advancement, identify any potential problems or roadblocks, and provide data for making adjustments to schedules, budgets, or resources if needed.
Project – It is a type of assignment, typically involving research or design, which is carefully planned to achieve a specific objective. It is a series of structured tasks, activities, and deliverables which are carefully executed to achieve a desired outcome. It consists of a group of tasks, performed in a definable time period, in order to meet a specific set of objectives. It is a temporary activity. It is a one-time program hence different from operations where tasks are repeated in a routine way. Every project has a life cycle, with a specific start and end. The work scope of a project can be categorized into definable tasks. Project has a budget within which it is required to be completed. During the execution of the project, there is likely requirement of multiple resources. Several of these resources can be scarce and may have to be shared with others. Project has a life cycle which includes (i) initiation, (ii) planning, (iii) execution, (iv) monitoring and control, (v) commissioning and handing over, and (vi) closing of the project activities. In case of mining terminology, project means a defined development or operation which provides the basis for environmental, social, economic and technical evaluation and decision-making. In the early stages of evaluation, including verification, the project can be defined only in conceptual terms, whereas more mature projects are to be defined in significant detail. Where no development or operation can currently be defined for all or part of a source, based on existing technology or technology currently under development, all quantities associated with that source (or part thereof) are classified in category F4. These are quantities which, if produced, can be bought, sold, or used.
Project boundaries – Project boundaries define the limits of a project, outlining what is included and excluded from its scope. They establish clear expectations for stakeholders, helping to prevent scope creep, manage resources effectively, and ensure the project stays on track and within its defined parameters. Key aspects of project boundaries are (i) scope which defines the specific deliverables, tasks, and activities that are part of the project, and those that are not, (ii) time which establishes deadlines, milestones, and the overall project duration, (iii) resources which determine the budget, personnel, and other resources allocated to the project, (iv) stakeholders which identify who is involved in the project and their respective roles and responsibilities, and (v) location which defines the physical or virtual space where the project is to be executed.
Project design phase – It is an early project stage focused on planning how to achieve objectives by outlining the project’s features, structure, and success criteria. It involves organizing ideas, resources, and procedures, producing a broad conceptual overview and potential strategies which are then presented to stakeholders for approval before project implementation. Deliverables from this phase can include flowcharts, prototypes, or sketches which show the logical solution before it is built.
Projected area – It is the area of a cavity, or portion of a cavity, in a mould or die casting die measured from the projection on a plane which is normal to the direction of the mould or die opening.
Projected balance sheet – It displays liabilities, equity of the owner and the assets which the organization is planning to have during the projected period of the financial plan.
Projected cash flow – It evaluates the state of the future working capital as well as it determines whether there is a necessity of borrowings or not.
Projected contact length – It is the length over which the roll separating force acts between the entry and exit in the rolling process, influencing the calculation of roll torque and the lever arm.
Projected cost – It is the predicted total expenditure for a project or its phase at the time of completion, updated throughout the project lifecycle based on actual costs and definitive information about the project’s scope, schedule, and resources. This estimate is important for financial planning, resource allocation, and decision-making, ensuring that sufficient funds are available and helping to identify and manage potential cost overruns.
Project engineer – Project engineer is a person who manages technical and engineering projects from planning to completion, ensuring projects are finished on time, within budget, and to the required technical and quality standards. They combine technical expertise with project management skills to coordinate diverse teams, bridge technical and project management roles, and provide technical guidance, acting as a crucial technical leader for the project.
Project evaluation and review technique (PERT) – It is also called programme evaluation and review technique. It is a statistical tool used in project management, which has been designed to analyze and represent the tasks involved in completing a given project. It is normally used in conjunction with the critical path method (CPM). It is a method of analyzing the tasks involved in completing a project, especially the time needed to complete each task, and to identify the minimum time needed to complete the total project. It incorporates uncertainty by making it possible to schedule a project while not knowing precisely the details and durations of all the activities. It is more event-oriented than start- and completion-oriented, and is used more for projects where time is the major constraint rather than cost. It is normally applied to very large-scale, one-time, complex, non-routine infrastructure projects. It is a management tool which relies on arrow and node diagrams of activities and events, where arrows represent the activities or work necessary to reach the events or nodes which indicate each completed phase of the total project.
Project implementation strategy and schedule – It consists of the implementation strategy of the project. The implementation schedule is normally presented in a detailed bar chart or in a PERT (project evaluation review technique) chart. The information is useful for project monitoring during its execution.
Projection – A projection is a potential future evolution of a quantity or set of quantities, frequently computed with the aid of a model. Projections are distinguished from predictions in order to emphasize that projections involve assumptions concerning, for example, future socio-economic and technological developments which may or may not be realized, and are hence, subject to substantial uncertainty.
Projection distance – It is the distance from the eye-piece to the image screen.
Projection lens – It is the final lens in the electron microscope corresponding to an ocular or projector in a compound optical microscope. This lens forms a real image on the viewing screen or photographic film.
Projections – A three-dimensional object can be represented in a single plane, such as on a sheet of paper, using projecting lines and planes. All projection theory is based on two variables namely line of sight (projecting lines) and plane of projection. The projection is produced by connecting the points where the lines of sight pierce the projection plane. As a result, the 3D object is transformed into a 2D view. If the distance from the observer to the object is infinite, then the projection lines are assumed to be parallel, and the projection is called a parallel projection. Parallel projection is orthographic if the plane of projection is placed between the observer and the object, and the plane is perpendicular to the parallel lines of sight.
Protection tube – It is a metal, graphite, or ceramic tube which shrouds and protects the wires of a thermo-electric pyrometer
Projection welding – It is a resistance welding process which produces coalescence of metals with the heat got from resistance to electric current through the work parts held together under pressure by electrodes. The resulting welds are localized at pre-determined points by projections, embossments, or intersections.
Project life cycle – It is a structured, phased framework which guides a project from its conception to completion, providing a roadmap for managing tasks, resources, and risks to achieve project goals. It typically consists of phases such as initiation, planning, execution, monitoring and control, and closure, ensuring a logical progression for efficient, organized, and successful project delivery.
Project management – It consists of the process of supervising the work of a team to achieve all project goals within the given constraints. This information is normally described in project documentation, created at the beginning of the development process. The primary constraints are scope, time, and budget. The secondary challenge is to optimize the allocation of necessary inputs and apply them to meet predefined objectives. The objective of project management is to produce a complete project which complies with the project’s objectives.
Project monitoring – It is an integral part of the project management. It provides understanding of the progress of the project so that appropriate corrective actions can be taken when the performance deviates significantly from the planned path. It consists of regular systematic collection and analysis of information to track the progress of the project implementation against pre-set targets and objectives. It is an important management tool. It is used properly, provides continuous feedback on the project implementation progress as well assists in the identification of potential successes and constraints to facilitate timely decisions. Effective monitoring of the project is a critical element of good project management. It supports informed and timely decision making by the management and provides accountability for achieving results. It is a key part of project cycle management. Project monitoring clarifies project objectives, links activities and their resources to objectives, translates objectives into performance indicators and sets targets, routinely collects data on these indicators, compares actual results with targets, and reports progress to the management and alerts the management about the problems which frequently gets cropped up during the implementation of the project.
Projector lens – It is the final optical component in a projector system which collects, magnifies, and focuses the light from the projector’s internal image source, projecting a large, clear, and magnified image onto a distant screen or surface. These lenses are designed to produce a real, inverted, and enlarged image by transmitting and refracting light, and they can be fixed-focus or feature adjustable zoom for different projection distances.
Project plan – It is a formal, approved document of the project which guides the project execution and is required for the management and control of the project. It forms the basis for all the actions which are required to be taken by the project team for the implementation of the project. The planning document is not of permanent nature since it is necessary to continuously update it as the work of the project progresses.
Project planning – It describes the suggested methodology of implementation of the project. It describes the recommended methodology for the procurement of the plant, equipment, and materials as well as for the works to be carried out at the plant site. It also recommends the types of the contracts to be entered so that the project can be completed in scheduled time.
Project profile – It is a concise document or a standardized set of parameters which provides a comprehensive overview of a project, summarizing its objectives, scope, timeline, budget, risks, key participants, and anticipated outcomes. It serves as an important communication tool for all stakeholders, enabling them to understand the project’s purpose and significance from the outset. Additionally, in some technical contexts, it can act as a configuration template to define default values and control parameters for project elements and systems.
Project specification – It is a formal, detailed document which outlines a project’s goals, deliverables, features, functionalities, and technical requirements. It serves as a foundational guide for all involved parties, including developers, designers, and stakeholders, to ensure everyone understands the project’s scope and requirements, which helps prevent misunderstandings and guides efficient implementation.
Project schedule – It is a timetable which lists a project’s tasks, milestones, and deliverables, along with their planned start and end dates, dependencies, and assigned resources, all organized in a logical, chronological sequence to help complete the project on time and within budget. It acts as a roadmap, providing a detailed plan of how the work is going to be accomplished and serving as a baseline for tracking progress and managing changes throughout the project lifecycle.
Project schedule network diagram – It is a graphical chart, typically using boxes and arrows, which visualizes the sequence of activities, their dependencies, and logical relationships within a project. It helps project managers and teams understand the project’s structure, plan and control the timeline, identify the critical path, and manage resources by showing how tasks are linked and how they influence the overall project duration.
Project team – It is a temporary group of individuals with diverse, complementary skills brought together by a project manager to achieve a specific project’s goals within a defined scope, schedule, and budget. This team can include full-time employees, part-time contributors, freelancers, and external experts, all collaborating through effective communication and cooperation to complete project tasks, deliver outcomes, and meet quality standards.
Prolonged annealing – It is a heat treatment process which involves holding a material at a high temperature for an extended period to achieve specific microstructural changes, such as the formation of a more homogeneous structure, reduction of defects, improvement in crystallinity, or alteration of its chemical properties. The ‘prolonged’ aspect refers to the extended duration of the heat exposure, which goes beyond typical short-term annealing and is used to achieve more significant or subtle transformations at a given temperature.
Prolonged heating – It refers to the extended exposure to high temperatures. It also describe the continuous exposure of a material, such as steel, to high temperatures, which can cause structural changes and damage like coarse grain formation.
Promethium (Pm) – It is a synthetic, radioactive chemical element with atomic number 61. It is a lanthanide, and all its isotopes are radioactive, making it one of only two such elements in the periodic table with stable neighbours. Promethium is rare, with only a small quantity naturally occurring in uranium ores, but it can be produced artificially.
Promoter – It is a substance that, when added to a catalyst, improves the catalyst’s activity or selectivity without directly participating in the reaction itself. Promoters are not catalysts themselves, but they improve the catalyst’s ability to speed up a reaction or produce a specific desired product.
Prompt neutrons – These are defined as the neutrons which are emitted immediately after a nuclear fission event, comprising around 99.35 % of the neutrons produced in thermal neutron fission reactions of uranium-235.
Prompt scrap – It is also called new scrap or industrial scrap. It is generated in steel-product manufacturing units and includes such items as turnings, clippings, and stampings leftover when parts are made from steel during the manufacturing processes. This material is typically sold to the scrap metal industry which processes it for recycling to steel plants and steel foundries. The composition of prompt scrap is well known and in principle new scrap does not need any major pre-treatment process before it is melted, although cutting to size can be necessary. Prompt scrap accounts for around 23 % of total steel scrap.
Prone area – It is a geographic location which is susceptible to a particular problem, disaster, or undesirable outcome, frequently at a higher frequency than average. This term is frequently applied to such as areas with a higher risk of accidents, fire, and explosions.
Pronounced effect – It refers to a change or result which is very noticeable, strong, or easily perceptible. It describes a substantial impact which stands out, rather than a subtle or minor one.
Prony brake – It is a dynamometer. It is a mechanical device used to measure the power output of an engine or motor by applying a frictional load to a rotating shaft. It consists of adjustable friction pads pressed against the shaft, generating a resistive torque which can be balanced with known weights on a lever arm. By measuring the applied weight and the radius of the lever arm, the brake torque can be calculated, which, along with the shaft’s rotational speed, determines the machine’s brake power.
Proof – It means to test a component or system at its peak operating load or pressure. It is a reproduction of a die impression in any material. It is frequently a lead or plaster cast.
Proof load – It is a pre-determined load, normally some multiple of the service load, to which a sample or structure is submitted before acceptance for use.
Proof load test – It is a non-destructive test where a product or structure is subjected to a specific load, typically between 85 % and 95 % of its yield strength, to verify it can handle its rated load without any permanent deformation or damage. This test ensures the component’s safety and integrity for its intended use and can be a diagnostic tool when analytical models are insufficient or unavailable.
Proof pressure – It is the test pressure which pressurized components sustain without detrimental deformation or damage. The proof pressure test is used to give evidence of satisfactory workmanship and material quality.
Proof stress (Rp) – It is a specified stress to be applied to a member or structure to indicate its ability to withstand service loads. It is the stress or applied load which produces a permanent elongation equal to a specific percentage of the original gauge length. In alloys which do not show a yield point it is used as an equivalent to the elastic limit. If a proof stress is specified, the non-proportional elongation is to be stated. The most common values used in specifications is 0.2 % or 1 % and the Rp symbol used for the stress will be supplemented by an index giving this prescribed percentage of the original gauge length, e.g. Rp0.2 = 0.2 % proof stress.
Propane – It is a three-carbon alkane with the molecular formula C3H8. It is a gas at standard temperature and pressure, but compressible to a transportable liquid. It is a by-product of natural gas processing and petroleum refining. It is frequently a constituent of liquefied petroleum gas (LPG), which is normally used as a fuel in domestic and industrial applications and in low-emissions public transportation.
Propane dehydrogenation – It is a catalytic process which converts propane (C3H8) into propylene (C3H6) and hydrogen (H2) using a noble metal catalyst at high temperatures of 500 deg C to 700 deg C, typically in a moving or fixed-bed reactor.
Propellant gas – It is a gas used to create pressure to propel something else, either by expanding in an aerosol can to spray out its contents or by burning to generate hot gases which propel rockets and projectiles. While common propellant gases like propane and butane are flammable and used for technical products, other propellants, such as compressed air, are non-flammable.
Propeller blade – It is one of the airfoil-shaped, twisted, lifting surfaces arranged radially around a central shaft, designed to generate thrust by interacting with a fluid (like air or water) as it spins. These blades create a pressure differential to cause fluid flow.
Propeller fans – These fans generate high air flow rates at low pressures. These fans are not combined with extensive ductwork since they generate little pressure and are inexpensive because of their simple construction. They achieve maximum efficiency, near-free delivery, and are frequently used in roof top ventilation applications. They can generate flow in reverse direction, which is helpful in ventilation applications. These fans have relative low energy efficiency and are comparatively noisy.
Propene – It is also known as propylene. It is a colourless, gaseous, unsaturated hydrocarbon with the chemical formula C3H6 or CH2=CH-CH3. As an alkene, it contains a carbon-carbon double bond and serves as a crucial building block, mainly as the monomer for polypropylene plastics. It is typically produced through processes like the steam cracking of petroleum.
Propensity scores – it is the predicted probabilities of receiving the treatment for different subjects. Subjects which have the same propensity scores can be treated in statistical analyses as though they are randomly assigned to treatment groups.
Propensity-score analysis – it is a statistical analysis which controls for propensity scores and thereby balances the distributions on control variables across groups of subjects.
Property – In science, a property is anything which describes a material or substance. It is a characteristic of that material. For example, how hard the material is, its colour, or its shape. Elasticity is a property of rubber. In other words, rubber is elastic.
Property characterization – It is the process of determining and describing the defining qualities and nature of something, whether it is a material, or a mathematical object, by analyzing its structure, physical attributes, or ownership status. It involves detailed analysis of structure and properties. In mathematics, it is finding conditions logically equivalent to an object’s definition.
Property degradation – It refers to the reduction or loss of a material’s desirable physical, chemical, or mechanical properties over time, leading to a decline in performance and eventual failure. This deterioration can result from exposure to factors such as heat, light, moisture, chemicals, mechanical stress, or other operational conditions. The concept is central to material selection, structural design, and ensuring the longevity and reliability of engineering components and structures.
Property of unique interest – It is a material property which is of such importance or uniqueness to the application that this single property predominates all other considerations in materials selection.
Property-prediction system (PPS) – It is used for simulating the metallurgical process occurring during heat treatment and predicting the microstructure and mechanical properties of quenched and tempered or case-hardened steel. The system consists of several modules, which form a logical chain for property prediction. Before starting to design a property prediction system, one has to ascertain first those internal parameters (for example, Ac3 temperature, transformation kinetic data, hardness values of the microstructural elements, and so on) which have the most determinative effects on the properties. Then the algorithm, the logical chain of these internal parameters, has to be stated and finally, the connections between the input data, the internal parameters, have to be investigated. If all of these connections are clear, mathematically formulated, and joined into a chain, one can handle this set of connections as a system. The programmes of the property prediction system are based on a phenomenological model of kinetics of transformation taking place in non-isothermal conditions. The programme permits the prediction of the progress of transformations, of the microstructure, and of the mechanical properties as a function of time and of position in the cross section of the heat-treated work-piece.
Proportion – For a variable with ‘n’ observations, of which the frequency of a particular characteristic is ‘r’, the proportion is r/n. For example, if the frequency of an activity is 11 times in 55 years, then the proportion is 11/55 = 0.2 of the years, or one fifth of the years.
Proportional constant – It is also known as proportional gain (frequently represented as ‘Kp’). It is a factor in proportional control which determines the magnitude of a controller’s output in direct proportion to the system’s error signal. It dictates how strongly the controller reacts to an error, balancing the need for a fast response with the risk of instability or a steady-state error.
Proportional control – It is a linear feedback control method where the output correction is directly proportional to the error signal, i.e., the difference between the desired setpoint and the measured process variable. This approach applies a corrective action that increases with the size of the error, aiming to bring a system closer to its target value more quickly and stably than on-off controls. The relationship is defined by the equation ‘control output = proportional gain (Kp) × error’. It is the ‘P’ part of a PID (proportional–integral–derivative) controller. With proportional action, the controller output is proportional to the quantity of the error signal.
Proportional control system – It uses a controller to produce an output signal which is directly proportional to the error signal, which is the difference between the desired setpoint and the actual measured process variable. By adjusting the control output in direct proportion to this error, the system aims to minimize the deviation and drive the process variable toward the setpoint, though it typically results in a non-zero steady-state error.
Proportional–integral–derivative (PID) controller – It is a feedback-based control loop mechanism which is normally used to manage machines and processes which need continuous control and automatic adjustment. It is typically used in industrial control systems and different other applications where constant control through modulation is necessary without human intervention. The proportional–integral–derivative controller automatically compares the desired target value (set-point) with the actual value of the system (process variable). The difference between these two values is called the error value. It then applies corrective actions automatically to bring the process variable to the same value as the set-point using three methods. The proportional (P) component responds to the current error value by producing an out-put which is directly proportional to the magnitude of the error. This provides immediate correction based on how far the system is from the desired setpoint. The integral (I) component, in turn, considers the cumulative sum of past errors to address any residual steady-state errors which persist over time, eliminating lingering discrepancies, and the third, the derivative (D) component predicts future error by assessing the rate of change of the error, which helps to mitigate overshoot and improve system stability, particularly when the system undergoes rapid changes. The proportional–integral–derivative controller reduces the likelihood of human error and improves automation.
Proportional integral gains – These are parameters within a proportional-integral (PI) controller, a widely used automatic control system component. The proportional gain (Kp) sets the immediate corrective action based on the current error between a desired setpoint and the actual system output, while the integral gain (Ki) determines how quickly the controller eliminates accumulated past errors, ensuring the system reaches the setpoint and minimizes steady-state error.
Proportionality – It defines a constant relationship between two variables, where a change in one variable produces a corresponding change in the other by a fixed, multiplicative factor, known as the constant of proportionality. This relationship can be directly proportional, described by Y= kX, meaning both variables increase or decrease together, or inversely proportional, described by Y = k/X, meaning as one increase, the other decreases. This principle is applied in different engineering contexts, such as control systems where controller output changes in proportion to the error signal or in physics where forces are proportional to other quantities.
Proportionality constant – It is the constant factor (frequently denoted as ‘k’) which quantifies the direct or inverse relationship between two varying physical quantities, such as stress and strain in Hooke’s Law, or the force on an object and its mass in Newton’s second law (where ‘k’ is the mass). This constant establishes a consistent linear relationship (Y = kX for direct proportionality, or Y = k/X for inverse) and can represent physical properties like material stiffness, or the scale of a map.
Proportional limit – It is the maximum stress a material can withstand while maintaining a linear relationship between stress and strain (the upper end of the straight-line portion of the stress-strain or load-elongation curve), as described by Hooke’s law. Beyond this point, the stress-strain curve becomes non-linear, marking the end of the material’s elastic and linear behaviour before permanent deformation occurs. Materials, in general, show some nonlinear elastic behaviour, so the elastic limit is (slightly) higher than the proportional limit.
Proportional valve – It is an electrically controlled valve which provides a continuously variable output, such as flow or pressure, which is directly proportional to an electrical input signal, frequently a current or voltage. Unlike binary on / off valves, proportional valves offer precise, modulated control, allowing for smooth, variable regulation of fluid or gas in applications requiring dynamic set points and repeatable control.
Proportioning probe – It is a probe which can vary, sample pure air ratios, between 100 % sample and 100 % pure air without substantially changing the total flow rate from the probe.
Proppant – It is a granular material, such as sand or ceramic microspheres, which is injected into a hydraulic fracture to prop open the created fractures in a geological formation. This process creates a highly conductive path for hydrocarbons (oil and gas) to flow from the reservoir into the wellbore, increasing production. Proppants are required to possess high crush resistance to withstand in-situ stresses, maintain long-term conductivity, and have specific size, shape (sphericity and roundness), and particle distribution.
Proppant pack – It is a collection of proppants which are utilized to maintain open fractures in geological formations, thereby improving the flow of oil and gas into the wellbore. It typically consists of uniformly sized, round grains with high crush resistance to withstand in situ stresses.
Proppant particles – These are materials suspended in fracturing fluids which are used to keep fractures open after hydraulic pressure is released, thereby creating conductive channels for hydrocarbon flow. They are characterized by high permeability, resistance to compression, low density, and good resistance to acids.
Propped cantilever – It is a type of beam which is supported at one end and has an additional support (prop) along its length, allowing it to carry opposing loads. Collapse occurs when two plastic hinges form, one at the built-in support and another at the prop position, because of the maximum bending moments.
Proprietary process – It is a unique method or system which is owned by an individual or organization and is not publicly available, protected by intellectual property rights like patents or trade secrets. These exclusive processes frequently provide a competitive advantage, creating value and enabling the owner to charge premium prices or achieve unique results which cannot be easily duplicated by others.
Proprietary system – It is a technology, software, or hardware designed, owned, and controlled by a single organization or vendor, featuring a closed architecture which restricts integration with other suppliers’ systems and makes the underlying design confidential and protected by intellectual property rights. These systems offer benefits like guaranteed compatibility within the supplier’s ecosystem but also lead to supplier lock-in, dependence, and potential lack of interoperability with non-proprietary alternatives.
Propyl – It consists of the alkyl functional group derived from either of the two isomers of propane, with the generic chemical formula –C3H7. It can occur as a substituent in organic compounds or exist independently as an ion or radical. In IUPAC (International Union of Pure and Applied Chemistry) nomenclature, the presence of a propyl substituent is indicated with the prefix propyl in the name of the compound.
Propyne – It is methylacetylene. It is a hydrocarbon characterized by the chemical formula C3H4 and the structural formula CH3C≡CH, which features a triple bond between two carbon atoms. It is a colourless, flammable gas used in specialty fuel applications, such as gas welding, and as a chemical intermediate in the production of synthetic rubber and plastics. It is part of MAPD (methylacetylene and propadiene) gas. It is also researched as a component in high-performance liquid rocket propellants.
Propylene – It is an unsaturated organic compound with the chemical formula CH3CH=CH2. It has one double bond, and is the second simplest member of the alkene class of hydrocarbons. It is a colourless gas with a faint petroleum-like odour.
Pro rata – It means in equal portions or in proportion. The term is used in many legal and economic contexts. More specifically, pro rata means (i) in proportionality to some factor which can be exactly calculated, (ii) to count based on an amount of time which has passed out of the total time, and (ii) proportional ratio.
Prolate rhombohedron – It is a type of rhombohedron with a common acute angle at its two opposite apices, giving it a stretched or elongated shape. A rhombohedron itself is a parallelepiped where all six faces are identical rhombi. The key difference between a prolate and an oblate rhombohedron is the nature of the angles at these apices; the prolate form has acute angles (less than 90-degree), while the oblate form has obtuse angles (higher than 90-degree).
Prospect – It is a mining area, the value of which has not been determined by exploration.
Prospecting – Prospecting is the systematic process of searching for a mineral deposit by narrowing down areas of promising enhanced mineral potential. The methods utilized are outcrop identification, geological mapping, and indirect methods such as geophysical and geochemical studies. Limited trenching, drilling, and sampling can be carried out. The objective is to identify a deposit which is to be the target for further exploration. Estimates of quantities are inferred, based on interpretation of geological, geophysical, and geochemical results.
Prospective projects – Prospective projects are potential future recovery by successful exploration activities. An Exploration project is associated with one or more major occurrences, i.e., a deposit that has not yet been demonstrated to exist by direct evidence (e.g., drilling and / or sampling), but has been assessed primarily on indirect evidence (e.g., surface, or airborne geophysical measurements).
Prospector – Prospector is a person who identifies the discovery, measure both width and length, and estimate the mineralized area.
Protected surface – It refers to a metal surface which is shielded from rust and corrosion during transportation and storage by temporary protectives, which create a water-resistant and oxygen-resistant barrier and can be easily removed to restore the surface to its original state.
Protected zone – It is also called protection zone. It is a defined area or component within a system which is monitored by a protective scheme to detect and isolate faults. The term can refer to areas within building ventilation systems or sections of a power system like a generator, transformer, or busbar. In power systems, these overlapping zones ensure that any fault within them causes specific circuit breakers to trip, isolating the faulty equipment without disturbing the rest of the system.
Protection device – It is a component designed to safeguard electrical systems, machinery, and people by detecting abnormal conditions, such as overcurrent, short circuits, and voltage variations, and then automatically taking action, like shutting down the system or isolating the fault. Common examples include fuses, circuit breakers, surge protectors, and relays, which prevent equipment damage, reduce downtime, and improve overall safety and reliability.
Protection layer – It is a mechanism, system, or component designed to reduce the risk of a serious event by controlling, preventing, or mitigating its consequences, ensuring the safety and integrity of a facility or process. These layers can be physical barriers, process controls, alarms, administrative procedures, or safety systems, and are frequently analyzed using methods like ‘layers of protection analysis’ (LOPA) to ensure they are independent, effective, and reliable safeguards against hazards.
Protection ratio – In electrical engineering, itis a ‘carrier-to-interference’ (C/I) ratio, indicating the minimum power margin needed at a receiver to distinguish a desired signal from unwanted interference for acceptable reception quality. In network engineering and redundancy, it refers to the ratio of working capacity to protection capacity, showing the level of backup or redundancy in a system.
Protection requirement – It defines a condition which a system, product, or service is required to meet to ensure safety, reliability, or security, frequently involving safety measures to prevent damage or harm to assets and people, and typically specified using the requirements engineering process of identification, analysis, specification, and validation. Protection requirements are a form of non-functional requirement which sets constraints on how a system behaves to prevent harm, rather than defining what it does.
Protection scheme – It is a coordinated system of devices, such as relays and circuit breakers, designed to automatically detect faults in an electrical system and isolate the affected equipment quickly and selectively, thereby maintaining system stability and minimizing the extent of the power loss or damage. These schemes involve primary and sometimes backup protection to ensure reliability, with the goal of disconnecting only the faulty part of the network while leaving healthy portions operational.
Protective atmosphere – It is a gas or vacuum envelope surrounding the part to be brazed, welded, or thermal sprayed, with the gas composition controlled with respect to chemical composition, dew point, pressure, flow rate, and so forth. Examples are inert gases, combusted fuel gases, hydrogen, and vacuum. It is also the atmosphere in a heat treating or sintering furnace designed to protect the parts or compacts from oxidation, nitridation, or other contamination from the environment.
Protective clothing – It refers to specialized garments and gear designed to safeguard individuals from different hazards, including physical, chemical, environmental, or biological risks, encountered in work or daily activities. It is essentially a form of personal protective equipment (PPE) which helps prevent injuries, illnesses, or exposure to harmful substances. Protective clothing comes in a variety of materials, each effective against particular hazards. Paper like fiber is used for disposable suits and it provides protection against dust and splashes. Treated wool and cotton adapts well to changing temperatures. It is comfortable and fire-resistant, and protects against dust, abrasions and rough and irritating surfaces. Duck is a closely woven cotton fabric which protects against cuts and bruises when handling heavy, sharp or rough materials. Leather is often used to protect against dry heat and flames. Rubber, rubberized fabrics, neoprene and plastics protect against certain chemicals and physical hazards. As with chemical protective gloves, the selection of appropriate chemical protective clothing involves a variety of factors. Examples of factors which influence the selection include the type of chemicals handled, the physical environment (site hazards), duration of contact, nature of contact (total immersion, splash, vapour or gas), PPE use and the accommodation of other selected ensemble equipment, decontamination and disposal, and limitations during temperature extremes, heat stress and other medical considerations.
Protective coatings – These are materials which can be applied as a thin film on suitable surfaces to inhibit or prevent degradation associated with the substrate. Surface coatings are important in maintaining the form, function, and properties of an object as they provide a shield against the environmental conditions.
Protective device – It is a component or system designed to detect abnormal and hazardous conditions (such as overcurrent, faults, over-temperature, or overpressure) and automatically initiate a corrective action, typically by disconnecting power or shutting down a process, to prevent damage to equipment, ensure safety of personnel, and maintain system reliability and stability.
Protective films – These are thin, flexible layers of material, frequently plastic, designed to shield surfaces from damage, scratches, and other hazards during handling, transportation, or storage. They act as a temporary barrier, preserving the integrity and appearance of several products and surfaces. These films are normally used in industries like electronics, automotive, and construction.
Protective gas – It is also known as a shielding gas or inert gas. It is a gas that is used to prevent unwanted chemical reactions, particularly oxidation and moisture-related degradation, during several industrial processes. These gases are typically non-reactive (inert) and are used to displace air or other reactive gases from the area where a process is taking place, ensuring the integrity of the material being worked on. In several industrial processes like welding, heat treatment, and additive manufacturing, exposure to oxygen can lead to oxidation (rusting, corrosion) or other undesirable chemical reactions. Protective gases ensure that the material being processed remains free from contaminants, which is crucial for maintaining the desired properties and quality of the material.
Protective layer – It is a surface coating or material barrier which shields internal components or systems from damage, corrosion, stress, or environmental hazards, thereby reducing the risk of failure or degradation. These layers can be formed through chemical processes like surface passivation or be applied as physical coatings, and their main function is to control, prevent, or mitigate adverse effects. A common example is galvanization, where zinc is coated onto steel to prevent rust.
Protective material – It is a substance or device designed to shield structures, systems, or individuals from harmful agents, impacts, environmental conditions, or hazards by acting as a barrier, adsorbent, or reactive element. These materials mitigate risks in fields like construction (e.g., safety netting, hard hats), where they protect workers and infrastructure from falling objects and chemical exposure, and in other areas where they might prevent corrosion, reduce wear, or provide thermal or ballistic protection.
Protective measure – It is an action, process, equipment, or design which safeguards people, property, or the environment from harm, specifically by reducing the severity of damage from a dangerous event, rather than preventing the event itself. Examples include fire sprinklers, safety interlocks on machinery, personal protective equipment (PPE), and facility designs which incorporate features like standoff distances to mitigate the impact of a threat.
Protective membrane – It is a thin layer of material designed to act as a barrier, safeguarding structures and systems from environmental factors like water, air, moisture, or handling stresses, while potentially providing structural support, insulation, or allowing selective passage of specific substances. Examples include waterproofing membranes in construction (like ethylene propylene diene monomer, EPDM or asphalt), bio-membranes in water treatment which allow certain molecules to pass, and protective layers on electronic components which prevent corrosion or damage.
Protective oxide film – It is a stable, non-porous layer of metal oxides which forms on a material’s surface, acting as a barrier to prevent further chemical attack and corrosion from the environment. This passive layer considerably slows down the corrosion rate by impeding the transfer of charge and corrosive agents to the underlying metal. Examples include the oxide films of aluminum and chromium, which effectively protect the metals from further oxidation.
Protective potential – It is the threshold value of the corrosion potential which has to be reached to enter a protective potential range.
Protective potential range – It is a range of corrosion potential values in which an acceptable corrosion resistance is achieved for a particular purpose.
Protective relay – It is an electro-mechanical or electronic device which detects faults on a power system and can signal circuit breakers to operate.
Protective structure – It is a physical barrier or enclosure designed to shield occupants, infrastructure, or other assets from different threats such as natural disasters, impacts, explosions, and hazards. These structures function by absorbing and dissipating energy from an event, effectively increasing survivability against a given threat. Examples include blast-resistant buildings, shelters for natural disasters, and roll-over protective structures (ROPS) for heavy machinery.
Protocol standards – These standards are also called ‘Standards of Practice’. Protocol standards are standards which define everything from the dimensions and electrical characteristics of a flashlight battery to the shape of the threads on a machine screw and from the size and shape of an IBM (International Business machines) punched card to the ‘quality assurance requirements’ for measuring equipment. Such standards can be defined as documents describing the operations and processes which are to be performed in order for a particular end to be achieved. They are called a ‘protocol’ by Europeans to avoid confusion with a physical standard.
Proton – It is an elementary particle with unit atomic mass approximately and unit positive electric charge. It is one of the two elementary particles found in atomic nuclei.
Protonation – It is the addition of a proton to a solute molecule, resulting in the formation of a conjugate acid, which can behave as a base in certain solvents, such as sulphuric acid. This process can lead to the production of ions like hydrogen sulphate in solution.
Proton conducting solid oxide fuel cell (PC-SOFC) – It is an electrochemical device that directly converts chemical energy into electricity using a ceramic electrolyte that transports protons (H+) rather than oxygen ions (O2-), as in conventional solid oxide fuel cells. This proton transport enables proton conducting solid oxide fuel cells to operate efficiently at intermediate to lower temperatures (450 deg C to 750 deg C) compared to traditional solid oxide fuel cells (which operate at 600 deg C to 1000 deg C), overcoming issues like cathode delamination and enabling the direct use of hydrogen fuel without dilution from water produced at the cathode.
Proton conductivity – It is the measure of a material’s ability to transport protons (H+) or protonic species (like H3O+) through it, which is crucial for applications such as proton exchange membrane (PEM) fuel cells and other energy systems that rely on proton movement for power generation. Materials used for this purpose are called proton conductors, and their high proton conductivity is directly related to factors like the ion exchange capacity (IEC) of the material and the presence of a suitable environment for proton transport through mechanisms like the Grotthuss or vehicular mechanisms.
Proton energy – It refers to the kinetic energy of protons, typically in high-energy physics applications. This energy dictates how protons interact with matter, leading to processes like ionization, displacement of atoms in materials, and nuclear reactions. Engineers design systems, such as particle accelerators for research by manipulating and controlling proton energy to achieve specific outcomes.
Proton-exchange membrane (PEM) – It is a specialized, semi-permeable polymeric membrane which acts as a solid electrolyte in electro-chemical devices like fuel cells and electrolyzers. Its primary engineering function is to facilitate the transport of protons (hydrogen ions) while simultaneously preventing the passage of reactant gases and acting as an electrical insulator between the device’s anode and cathode.
Proton-exchange membrane (PEM) fuel cell – It is an electro-chemical device which converts hydrogen and oxygen into electricity, heat, and water, using a polymer electrolyte membrane to allow only protons (hydrogen ions) to pass from the anode to the cathode. These cells operate at low temperatures, are compact, have high power density, and are well-suited for applications like light-duty and stationary power, although they require pure hydrogen fuel.
Proton-exchange membrane (PEM) process – It is also known as polymer electrolyte membrane process. It is a modern electrolyzer technology known for higher efficiency and production rates. In this technology, a solid membrane is used to separate hydrogen. This process is more simple and agile compared to alkaline electrolysis process and allows for operation under differential pressures, typically 3 megapascals to 7 megapascals. Proton-exchange membrane process yields higher-quality hydrogen and can be operated intermittently, but is also expensive and has lower production rates than alkaline electrolysis process. Proton-exchange membrane electrolyzers perform better with fluctuating input currents and integrate better with intermittent power generation (e.g., wind and solar). In addition, they have the potential to produce hydrogen at higher pressures by electro-chemical compression. Proton-exchange membrane electrolyzers’ capability to operate highly dynamically with intermittent load and at higher pressure balances their higher capital cost. These costs are expected to drop through innovation and deployment), which can lead to higher adoption of proton-exchange membrane systems.
Proton precession magnetometer – It is a geo-physical instrument which measures magnetic field intensity in terms of vertical gradient and total field.
Prototype – It is a full-scale working model of the design which is technically and visually complete.
Prototype testing – It is a systematic evaluation of an early, simplified version of a product or system (a prototype) to assess its performance, identify design flaws, validate functionality, and gather user feedback before full-scale production. This iterative process allows engineers to test specific ideas, refine the design based on data and user insights, and reduce the risk of costly errors by uncovering issues early in the development lifecycle.
Protuberances – These are the small-scale irregularities on a surface. These are minute imperfections on a seal face or surface of a mating ring which are the result of normal surface finishing processes. Protuberances, their shapes, sizes, and mechanical properties are the basis for developing several theoretical models for friction, lubrication, and wear behaviour.
Protrusion – It is imperfection which can occur during the moulding or firing process of a brick or a block.
Proved Mineral reserves – Proved Mineral reserves is the Economically mineable part of Measured Mineral resource.
Proved Ore reserve – A Proved Ore reserve is the economically mineable part of a Measured Mineral resource. A Proved ore reserve implies a high degree of confidence in the Modifying factors.
Proven acceptable range (PAR) – It is defined as a characterized range of a process parameter for which operation within this range, while keeping other parameters constant. It results in producing a material meeting relevant quality criteria. A proven acceptable range allows deliberate change in one parameter without changing the others outside their normal operating range / target.
Proven reserves – These are reserves which have been sampled extensively by closely spaced diamond drill holes and developed by underground workings in sufficient detail to render an accurate estimation of grade and tonnage. It is also called ‘measured reserves’.
Prow formation – In sliding metals, it is the formation of a wedge or wedges of plastically sheared metal in local regions of interaction between sliding surfaces. This type of prow is also known as a wedge. It is similar to a built-up edge. In hydrodynamic lubrication, it is the establishment of a pressure gradient in a fluid flowing into a converging channel. This is also known as the wedge effect.
Proximate analysis – It is defined as a technique to measure the chemical properties of a compound based on four particular elements namely moisture content, fixed carbon, volatile matter and ash content. The various parameters of proximate coal analysis in case of thermal coal have considerable significance. Fixed carbon acts as a main heat generator during burning and it gives a rough estimate of heating value of coal. The volatile matter also contributes to the heating value of coal. Increase in percentage of volatile matter in coal proportionately increases flame length and helps in easier ignition of the coal. It has also had implications regarding minimum limit of furnace height and volume and influences secondary oil support. Ash is an impurity which does not burn. It is important parameter in design of furnace grate, combustion volume, pollution control devices and ash handling plant. Ash increases transportation, handling, storage cost of the coal and affects the combustion efficiency and the furnace efficiency. It also causes clinkering and slagging problems in the furnace. Moisture increases transportation, handling, storage cost and decreases the heat content per kilogram of coal. It increases heat loss because of the evaporation and superheating of vapour. Moisture helps in binding of the fines and in radiation heat transfer.
Proximity effect – It is the increase in circuit resistance when the magnetic fields of multiple alternating currents interact.
Proximity sensor – It is a sensor in a conveyor system which detects the presence or absence of materials without physical contact, necessitating regular inspections for accurate sensing and responsiveness.
P-sensor – It refers to a pressure sensor, a device which detects and measures gas or liquid pressure and converts it into an electrical signal. Alternatively, it can refer to a piezoresistive or piezoelectric sensor, both of which use physical stress (like pressure) to change electrical properties, or even an interferometric fibre optic sensor which detects changes in light phase to measure physical quantities.
Pseudo-binary system – It is a three-component or ternary alloy system in which an intermediate phase acts as a component. It is a vertical section through a ternary diagram.
Pseudo-capacitance – It is a mechanism for storing electrical charge in electrochemical devices, where Faradaic (electron-transfer) reactions, such as redox or intercalation, occur at the electrode-electrolyte interface. Unlike conventional electrochemical double-layer capacitors (EDLCs), which rely on electrostatic ion accumulation, pseudo-capacitance utilizes fast, reversible chemical reactions to store energy. This Faradaic process allows for higher energy densities than electrochemical double-layer capacitors and higher power densities than batteries, making pseudocapacitive materials desirable for applications needing both.
Pseudo-capacitors – These are defined as devices which allow charge transfer between electrodes and electrolytes, storing charge through processes such as electrosorption, redox reactions, and intercalation, which results in higher capacitance and energy density compared to electric double-layer capacitors (EDLCs).
Pseudo-carburizing – It consists of simulating the carburizing operation without introducing carbon. This is usually accomplished by using an inert material in place of the carburizing agent, or by applying a suitable protective coating to the ferrous alloy.
Pseudo-critical pressure – It is a calculated value used for multi-component gas mixtures, representing the weighted average of the critical pressures of the individual components on a mole fraction basis. It is an analytical property which allows engineers to treat a gas mixture as a single equivalent substance by providing pseudo-critical parameters, which are then used to calculate pseudo-reduced properties. These pseudo-critical properties enable the use of generalized charts and correlations for predicting the behaviour of real gas mixtures, such as their compressibility.
Pseudo-critical properties – These properties (temperature and pressure) are calculated values for a multi-component gas mixture, not the true critical point of the mixture, which serve as input for generalized correlations based on the principle of corresponding states. These pseudocritical properties are determined using mixing rules which consider the critical properties of pure component gases and the mixture’s specific gravity or composition to accurately estimate mixture properties like reduced temperature and pressure.
Pseudo-crystalline – It describes a solid which appears crystalline on the surface or macroscopically but lacks a true, long-range, repeating atomic order characteristic of a genuine crystal. These materials frequently have short-range order in their atomic arrangement but do not show the consistent, three-dimensional, ordered structure of a crystalline solid. They are also sometimes referred to as semi-crystalline materials or, more broadly, amorphous solids or pseudo-solids, like glass or some polymers.
Pseudo-nitriding – It consists of simulating the nitriding operation without introducing nitrogen. This is normally accomplished by using an inert material in place of the nitriding agent or by applying a suitable protective coating to the ferrous alloy.
Pseudo-plastic fluid – It is also known as a shear-thinning fluid. It is a non-Newtonian fluid which becomes less viscous (flows more easily) when a shear force, pressure, or velocity is applied. Its internal structure breaks down under stress, reducing resistance to flow, which is the opposite of Newtonian fluids where viscosity remains constant regardless of shear rate. Common examples include polymer solutions, and paints etc.
Pseudo-plastic behaviour – It is a decrease in viscosity with increasing shear stress.
Pseudo-pressure – It is a mathematical pressure function used in reservoir engineering to simplify the behaviour of gases, which have variable viscosity and compressibility (Z-factor) with pressure. It transforms the variable-property gas flow equations into a form analogous to single-phase liquid flow equations, allowing them to be solved more easily for flow in porous media.
Pseudo-R2 measure – It consists of any of several analogs of the linear regression ‘R2’ used for non-linear models such as logistic regression, Poisson regression, and Cox regression, etc.
Pseudo-stress – It refers to the output derived from techniques such as fixed reactive analysis, inertia relief analysis, and modal transient response analysis, which is utilized to estimate local true stresses and strains at stress concentration areas for fatigue damage assessment.
Pseudo-wollastonite – It is called beta-wollastonite. It is a high-temperature, polymorphous form of wollastonite (CaSiO3) and a constituent of ultrahigh-temperature combustion-metamorphic and igneous rocks, slags, and glasses, characterized by Si3O9 ternary rings within its structure. Unlike the more common low-temperature wollastonite, pseudo-wollastonite is rare in natural geological environments but forms in the presence of extreme heat, such as pyro-metamorphism or spontaneous combustion events.
psi – It is abbreviation for pounds per square inch. 1 psi is equal to 6.89476 kilopascal.
Psycho-social work environment – It is the content of work and work demands, the social relationships at work, the organization of work and the work culture, which each can affect the mental and physical well-being of workers including management. All these work aspects are sometimes referred to as workplace stressors, which may have cognitive, emotional or motivational effects on workers.
P-T diagram – It is also known as a phase diagram. It is a two-dimensional graph of phase relationships in a system of any order by means of the pressure and temperature variables. It is a graphical representation of the physical states (phases) of a substance under different pressure and temperature conditions. It essentially maps out the boundaries between solid, liquid, and gaseous phases, showing the conditions under which each phase is stable and when transitions between phases occur. Common components of a phase diagram are lines of equilibrium or phase boundaries, which refer to lines that mark conditions under which multiple phases can coexist at equilibrium. Phase transitions occur along lines of equilibrium. Metastable phases are not shown in phase diagrams as, despite their common occurrence, they are not equilibrium phases. Triple points are points on phase diagrams where lines of equilibrium intersect. Triple points mark conditions at which three different phases can coexist.
PTFE-coated conveyor belt – It is a conveyor belt coated with poly-tetra-fluoro-ethylene (PTFE) for enhanced non-stick properties and resistance to heat. Periodic inspections are necessary to assess wear and overall belt condition.
P-T-X diagram – It is a three-dimensional graph of the phase relationships in a binary system by means of the pressure, temperature and concentration variables.
P-type doping – It is the process of intentionally adding trivalent impurity atoms (acceptors) to an intrinsic semiconductor, like silicon, to create a surplus of holes (electron vacancies) which act as positive charge carriers. This makes the material an extrinsic, p-type semiconductor, where holes are the majority charge carriers and are responsible for electrical conductivity. Common trivalent dopants include boron, aluminum, and gallium.
p-type semiconductor – It is a group IV intrinsic semiconductor such as silicon (Si) doped with group III boron (B) or indium (In) as an impurity. Group IV elements are tetravalent elements with four valence electrons, while group III elements are trivalent elements with three valence electrons.
P-type silicon – It refers to silicon which has been doped with acceptor impurities to create a surplus of holes, which act as positive charge carriers. This doping process is essential in the construction of various semiconductor devices, including photodetectors.
Public acceptability – It is the overall degree of acceptance, support, or agreement by the general population or a community for a proposed policy, technology, or action, encompassing attitudes, behaviours, and perceptions which influence its successful implementation and long-term sustainability. It is a complex process, shaped by factors such as perceived risks and benefits, ethical considerations, cultural backgrounds, information sources, and the extent of public participation in decision-making.
Public relations – It is a strategic communication process which builds mutually beneficial relationships between organization and its publics. It is the deliberate, planned and sustained effort to establish and maintain mutual understanding between on organization and its publics. It is the management of communication between the organization and its publics. It is the attempt by information persuasion and adjustment to engineer public support for an activity, cause, movement or organization. It helps the organization and its publics adapt mutually to each other. Public relations is a distinctive management function which helps establish and maintain mutual lines of communication, understanding, acceptance, and cooperation between an organization and its publics.
Public reports – These are reports prepared for the purpose of informing investors or potential investors and their advisers on Exploration results, Mineral resources or Ore reserves. They include, but are not limited to, annual and quarterly company reports, press releases, information memoranda, technical papers, website postings, and public presentations.
Public utilities – Public utilities are meant to supply goods and services which are considered necessary such as water, gas, electricity, telephone, waste disposal, and other communication systems. The transmission lines used in the transportation of electricity, or natural gas pipelines, have natural monopoly characteristics. A public utility organization is an organization that maintains the infra-structure for a public service (frequently also providing a service using that infrastructure).
Puck criterion – It is a method for differentiating failure modes in composite materials by identifying the critical fracture plane where stresses lead to failure of either the matrix or the fibre. It considers several loading situations and needs knowledge of the critical fracture plane and parameters for load sharing between fibres and matrix.
Puckering – It is wrinkling or buckling in a drawn shell in an area originally inside the draw ring.
Puckers – These are areas on prepreg materials where material has locally blistered from the separator film or release paper.
Puddle – It is a non-standard term for weld pool.
Puddling – It is the process of converting pig iron to bar (wrought) iron in a coal fired reverberatory furnace. It was developed in England during the 1780s. The molten pig iron was stirred in a reverberatory furnace, in an oxidizing environment to burn the carbon, resulting in wrought iron. It was one of the most important processes for making the first appreciable volumes of valuable and useful bar iron (malleable wrought iron) without the use of charcoal. Eventually, the furnace has been used to make small quantities of specialty steels.
Puffed compact – It is a compact which is expanded by internal gas pressure.
Pugh concept selection method – It is a group process of selecting a design concept or material in which the selection criteria and concepts are arranged in matrix form, and for each criterion the concepts are compared one at a time to a datum (reference) concept.
Pug mill – It is a machine in which clay or other materials are extruded in a plastic state or a similar machine for the trituration of ore. Industrial applications are found in pottery, bricks, cement and some parts of the concrete and asphalt mixing processes. A pugmill can be a fast continuous mixer. A continuous pugmill can achieve a thoroughly mixed, homogeneous mixture in a few seconds, and the right machines can be matched to the right application by taking into account the factors of agitation, drive assembly, inlet, discharge, cost and maintenance.
Pullback force – It refers to the force exerted on a reamer during drilling, which influences the lateral vibration intensity and can lead to substantial dynamic loads on the cutting teeth, resulting in potential damage or failure.
Pull cracks – In a casting, these are cracks which are caused by residual stresses produced during cooling and that result from the shape of the object.
Pull cord switch – It is a safety device in a conveyor system which stops the conveyor when the pull cord is activated, demanding regular inspections for proper tension and responsiveness.
Pulley – It is a wheel on an axle or shaft which is enabling a taut cable or belt passing over the wheel to
move and change direction, or transfer power between itself and a shaft. A sheave or pulley wheel is a pulley using an axle supported by a frame or shell (block) to guide a cable or exert force. A pulley can have a groove or grooves between flanges around its circumference to locate the cable or belt. The drive element of a pulley system can be a rope, cable, belt, or chain. In a conveyor belt system, pulleys are rotating cylinders that support and guide the conveyor belt. They are crucial for driving the belt, changing its direction, and maintaining proper tension. Pulleys are essential components that ensure the smooth and efficient operation of the conveyor system.
Pulley block – It is a system of pulleys which supports a load by distributing the weight across multiple sections of rope, allowing for a mechanical advantage where the effort needed to lift the load is reduced in proportion to the number of pulleys used.
Pulley diameter – It refers to the measurement across the circular face of a pulley. It is a crucial dimension for proper belt tracking, tension, and overall system performance. Specifically, it is the diameter of the pulley’s cylindrical body where the conveyor belt makes contact. There are requirements on the minimum pulley diameter. A bigger diameter can have a positive effect on belt life.
Pulley groove – It is the channel or depression around the circumference of a pulley wheel designed to hold a belt, rope, or cable, ensuring it stays in place while transferring power or changing the direction of a force. These grooves vary in shape depending on the type of belt used (like V-grooves for V-belts) and are critical for a pulley’s effective operation, power transmission efficiency, and the longevity of the belt.
Pulley lagging – It is the application of a layer of material to pulley surfaces to enhance grip and reduce slipping with the conveyor belt, necessitating regular inspections for maintenance and effectiveness.
Pulley wheel – It is a grooved wheel which rotates on a shaft or axle and is used in conjunction with a rope, belt, or chain to change the direction of force or to transmit power between two components. These simple machines can also provide mechanical advantage to multiply force, allowing heavy loads to be lifted with less effort, or they can be used in belt and chain drives to transfer power from one rotating shaft to another.
Pull gun technique – It is a non-standard term for backhand welding.
Pull-off tensile strength – It refers to the measure of the bond strength between a substrate and an overlay, specifically evaluated through the pull-off test, which is noted to provide conservative bond strength values across various investigations.
Pull-off test – It measures the bond strength between a surface or layer and its coating or substrate by applying a perpendicular force to a dolly (pull stub) glued to the surface, eventually pulling it off. The force needed to cause failure is recorded, indicating the adhesion strength of the coating, material, or component. This method is used to evaluate the adhesion of coatings on different substrates like metal, concrete, and wood, and to assess the bond strength in composites or other materials.
Pull-out resistance – It is the force needed to withdraw an embedded element (like a geosynthetic, anchor, or bolt) from the surrounding material, which can be soil, rock, or concrete. It is a measure of the anchorage’s effectiveness, calculated as the total friction and bearing forces resisting the element’s movement. This resistance is crucial for the stability of structures such as retaining walls, transmission towers, and reinforced soil, as it determines the anchor’s ability to withstand uplift, wind, or seismic forces.
Pull-out test – It measures the force needed to extract an embedded component, such as a rebar or anchor, from a surrounding material like concrete or soil. This test assesses the bond strength, load-carrying capacity, and overall structural durability of the composite material by evaluating the quality of the connection between the component and the substrate. It is a crucial method for quality control, material selection, and validating designs in several civil and structural engineering applications.
Pull through – It is a reddish spot in a porcelain enamel coating caused by iron pickup during enameling, iron oxide left on poorly cleaned base metal, or burrs on iron or steel base metal which protrude through the coating and are oxidized during firing. It is also called copperhead.
Pull ventilation – It refers to a system in which air or fluid is removed from a space, typically using an exhaust hood, to eliminate contaminants. This process can be part of a push-pull ventilation system, where a jet creates a flow that directs the contaminated fluid towards the exhaust.
Pulp – It is pulverized or ground ore in solution.
Pulp density – It refers to the quantity of solid material suspended in a liquid, expressed either as a percentage of solids by weight or as the weight of a unit volume of the pulp. It basically measures the thicknesses or concentration of the slurry. This parameter is crucial in processes like mineral flotation and bioleaching because it significantly affects the efficiency, recovery, and grade of the final product.
Pulp moulding – It is the process by which a resin- impregnated pulp material is pre-formed by application of a vacuum and subsequently is oven cured or moulded.
Pulsating energy – It refers to a rhythmic surge or wave of energy which increases and decreases in intensity periodically, as seen in pulsed lasers or pulsed electric fields. This phenomenon is distinct from continuous energy, where the power remains constant. It involves the delivery of a finite quantity of energy in short bursts, frequently over a specific time interval.
Pulsation – It is the rapid fluctuations in pressure.
Pulsation analysis – It is the process of evaluating and quantifying the pressure and flow variations (pulsations) generated by positive displacement pumps and compressors, to understand their impact on system performance and mechanical integrity. The objective is to prevent potential damage like fatigue failure, equipment damage, and reduced efficiency by ensuring vibrations and pressure fluctuations are within safe, acceptable levels and by designing effective solutions such as pulsation dampeners.
Pulsation damper – It is a device which reduces pressure fluctuations in a fluid system by smoothing out rapid pressure spikes and dips, typically caused by reciprocating pumps. It functions by storing energy during pressure peaks and releasing it during pressure troughs, resulting in a more stable and uniform fluid flow and protecting system components from stress, damage, and premature failure.
Pulse amplitude – It refers to the magnitude of a pulse, such as its peak voltage, current, or intensity at a given moment, and is a fundamental parameter in ‘pulse amplitude modulation’ (PAM). This modulation technique involves varying the amplitude of a series of pulses to encode information, with the pulse’s amplitude being proportional to a sample of a continuous signal.
Pulse amplitude modulation (PAM) – it is a digital signaling technique which transmits information by varying the amplitude of a pulse train to correspond to the amplitude of the message signal at specific sampling intervals. The signal is generated by multiplying a continuous message signal with a periodic pulse train, resulting in a series of pulses whose heights represent the original signal’s instantaneous values. Key applications include high-speed data communication, such as in Ethernet standards and modern graphics card technology, and as an electronic driver for light emitting diodes.
Pulse circuits – These are electronic circuits designed to generate, process, and manipulate electrical signals which are in the form of pulses e.g., short, non-sinusoidal, transient bursts of energy with distinct rise and fall times, similar to on / off signals. These circuits are fundamental to digital electronics and operate by modifying the shape, amplitude, or duration of these pulse signals for different control and data transmission purposes.
Pulse-code modulation – It is a system for conveying analog information by altering some property of a stream of pulses.
Pulse compression – It is defined as a technique in ultrasound imaging which involves transmitting longer duration, lower amplitude pulses with frequency modulation, which enhances signal-to-noise ratio (SNR) and allows for improved penetration and resolution through the use of appropriate coding and a matched filter for decoding.
Pulsed arc – It is an electric arc created by a pulsed direct current power supply which repetitively makes and breaks the arc circuit at a specific frequency. This pulsing technique, frequently used in welding and plasma sources, allows for higher peak currents and lower average power compared to a continuous arc, enabling better control over heat input, improved material transfer, and reduced cooling requirements.
Pulsed flow – It refers to a fluid flow which experiences periodic variations in its velocity and / or pressure, frequently characterized by a superimposed oscillating component on a stationary or base flow. This non-steady, unsteady flow regime is used to improve system performance in applications like fluidized beds for better mixing, in pulse flow reverse osmosis (PFRO) for improved cleaning.
Pulsed laser – It emits light in discrete, short bursts (pulses) rather than a continuous beam, enabling high peak power and precise energy delivery to a material. This allows engineers to achieve material ablation, high-precision machining, and rapid chemical process studies by rapidly heating a small volume of material to high temperatures without substantial heat diffusion. Common applications include pulsed laser deposition (PLD) for thin-film growth and surface cleaning in manufacturing processes.
Pulsed-laser atom-probe field-ion microscope – It is a time-of-flight atom-probe field-ion microscope has been developed which uses nano-second laser pulses to field evaporate surface species.
Pulsed laser deposition (PLD) – It is a physical vapour deposition (PVD) technique where a high-power pulsed laser beam is focused inside a vacuum chamber to strike a target of the material that is to be deposited. This material is vapourized from the target (in a plasma plume) which deposits it as a thin film on a substrate (such as a silicon wafer facing the target). This process can occur in ultra-high vacuum or in the presence of a background gas, such as oxygen which is commonly used when depositing oxides to fully oxygenate the deposited films.
Pulsed laser processing – It is a technique using short bursts of high-energy laser light to precisely alter materials, either by removing material (ablation) or adding material (deposition). The brief, intense pulses allow for rapid heating and material removal or transformation, enabling applications like creating micro-grooves, fabricating thin films, and precisely cleaning surfaces without considerabtly heating the surrounding bulk material.
Pulsed source – It generates intermittent bursts of current or voltage, deviating from a constant baseline value for a specified duration before returning to it. These sources are used to create different wave-forms like square, triangular, or saw-tooth waves for simulating circuit behaviour, controlling devices, or applying pulsed power for applications such as laser deposition. Key parameters for defining a pulsed source include the initial and final values, pulse width, rise and fall times, and the period between pulses.
Pulsed stimulated Brillouin microscopy (PSBM) – It is a non-contact, optical technique used to image the mechanical properties of biological samples. It utilizes a pulsed laser to improve the normally weak Brillouin scattering signal, allowing for high-sensitivity imaging of live and fragile specimens. By analyzing how light scatters off acoustic waves within a material, pulsed stimulated Brillouin microscopy can reveal information about its elasticity and viscosity.
Pulse-echo (PE) ultrasonic inspection – It is a non-destructive testing (NDT) method which uses a single transducer to emit high-frequency sound waves into a material, which then reflect off internal defects or material boundaries as echoes. By analyzing the timing and amplitude of these returning signals, engineers can identify and locate flaws like cracks, voids, or corrosion, and measure material thickness with just one side of access.
Pulse energy – It is the quantity of energy contained within a single, discrete burst of energy (a pulse), typically a laser pulse or an electrical pulse, measured in joules (J). It represents the total energy released by a pulsed system, calculated by integrating power over time, and influences effects like a laser’s deposition zone or the discharge energy in a pulsed power system.
Pulse frequency – It refers to the number of pulses or cycles that occur in one second, typically measured in hertz (Hz). It is the reciprocal of the pulse period (the time between the start of one pulse and the start of the next) and dictates how frequently a pulsed signal repeats.
Pulse generator – It is an electronic instrument or circuit which produces rectangular or shaped pulses for testing and stimulating digital and timing circuits. It functions as test equipment, providing a controlled, precise source of pulses with user-adjustable parameters like frequency, duration, and amplitude to evaluate the performance and characteristics of electronic devices and systems.
Pulse-jet fabric filter – It is an industrial dust collector which uses fabric bags to filter particulates from a gas stream, with cleaning achieved by a momentary burst of high-pressure compressed air from the inside of the bags. Dirty gas flows from outside to inside the bags, collecting a dust cake on the outer surface. The compressed air pulse, directed through a venturi, inflates the bag and creates a shock wave which dislodges the dust, which then falls into a hopper below. This technology is common in industry and helps control air pollution while allowing for compact designs due to continuous, on-line cleaning.
Pulse off time – It refers to the duration during which the electrical discharge diminishes, allowing for dielectric reionization and the reduction of temperature in plasma channels between electrodes and the work-piece. It plays a crucial role in controlling the stability of electrical discharge machining (EDM) processes throughout material deposition and modification.
Pulse on time – It is the time interval during which the applied current flows through the electrodes, leading to dielectric breakdown and material removal from the work-piece surface. Longer pulse on times result in higher material removal rates and rougher surface finishes, while shorter times yield smoother surfaces.
Pulse output – It is a signal or a sequence of binary signals (on / off, or high / low) where each distinct pulse represents a specific, proportional quantity of a measured entity, such as a unit of energy, volume of fluid, or gas. These digital outputs are generated by meters and sensors to provide data to higher-level systems like programmable logic controllers, supervisory control and data acquisition, or data loggers for applications in energy monitoring, process control, and automated data collection.
Pulse period – It is the duration of time between successive pulses in a signal, typically measured in milliseconds, e.g., at a target speed of 10 pulses per second (pps), the pulse period will be 100 milli seconds.
Pulse, resistance welding – It is a current of controlled duration of either polarity through the welding circuit.
Pulse repetition rate – It refers to the number of pulses emitted per unit time by a system, such as a laser or radar. It is crucial in determining the maximum counting rate for accurate measurements in various scientific applications.
Pulse transformer – It is a transformer designed to create or transmit pulses.
Pulse width modulated (PWM) signal – it is a digital signal where the duration (width) of its pulses is varied to encode information or control the average power delivered to a load. By rapidly switching a signal on and off, the duty cycle (the ratio of ‘on’ time to the total period) determines the overall average power, with a higher duty cycle providing more power. Pulse-width modulation is used in applications like motor control, dimming light emitting diodes, and power electronics to provide analog-like control from a digital output.
Pulse-width modulation (PWM) – It is the transmission of information by varying the duration of pulses, or, varying the average output voltage of a power converter by varying the duration of pulses. It is
useful for controlling the average power or amplitude delivered by an electrical signal. The average value of voltage (and current) fed to the load is controlled by switching the supply between 0 % and 100 % at a rate faster than it takes the load to change significantly. The longer the switch is on, the higher the total power supplied to the load. Along with maximum power point tracking (MPPT), it is one of the primary methods of controlling the output of solar panels to that which can be utilized by a battery. Pulse-width modulation is particularly suited for running inertial loads such as motors, which are not as easily affected by this discrete switching. The goal of pulse-width modulation is to control a load. However, the pulse-width modulation switching frequency is to be selected carefully in order to smoothly do so.
Pulse-width modulation (PWM) technique – It is a technique for controlling the average power delivered to a load by rapidly switching a power signal between its on and off states. By varying the duty cycle (the ratio of the on-time to the total period of the pulse), the average power can be precisely regulated without changing the signal’s constant amplitude. This digital method allows for efficient analog control of devices like motors, light-emitting diodes, and heating systems.
Pultrusion – It is a cost-effective automated process for manufacturing continuous, constant cross-section composite profiles. It refers to both the final product and the process. Most simply, it refers to a method of manufacture wherein a collection of reinforcements saturated with reactive resin is pulled through a heated die which imparts the final geometry to the composite profile. In virtually every case, the continuous reinforcing fibre choices are integral to the processibility and the finished product properties. The resin matrix used is typically a liquid thermosetting resin, which reacts exothermically when heat is introduced to create a cross-linked polymer with exceptional engineering properties. The resulting thermoset composite profile cannot be reshaped or otherwise altered within its operating temperature range. In contrast, the extrusion of aluminum and thermoplastic materials normally involves unreinforced (homogeneous) materials which are heated and pushed through a die, then allowed to cool into the final solid shape. These materials can be reheated and reshaped several times with little loss of basic properties.
Pulverization – It is the process of reducing metal powder particle sizes by mechanical means. It is also called comminution or mechanical disintegration.
Pulverized coal – It is raw coal which has been crushed and ground into fine particles, typically resembling dust, and then transported in an air stream for combustion. This powdery form, known as pulverized coal, is used extensively in fossil fuel power plants to generate electricity and in industries like steel production, because of its increased surface area which promotes faster and more efficient burning.
Pulverized coal-fired (PCF) boiler – It is an industrial or utility boiler which generates thermal energy by burning pulverized coal which is blown into the firebox. The basic idea of a firing system using pulverized coal is to use the whole volume of the furnace for the combustion of solid coal. Coal is ground to the size of a fine grain, mixed with air and burned in the flue gas flow. Coal contains mineral matter which is converted to ash during combustion. The ash is removed as bottom ash and fly ash. The bottom ash is removed at the furnace bottom. Pulverized coal-fired boilers have a high efficiency but a costly SOx (oxides of sulphur) and NOx (oxides of nitrogen) control. Almost any kind of coal can be reduced to powder and burned like a gas in a pulverized coal fired boiler.
Pulverized coal injection (PCI) – It is a process which involves injecting large volumes of fine coal particles into the raceway of the blast furnace. Pulverized coal is an important auxiliary fuel used in the blast furnace ironmaking. Pulverized coal injection provides auxiliary fuel for partial coke replacement and has proven both economically and environmentally favourable. It can result in substantial improvement in the blast furnace efficiency and hence contribute to the reductions of energy consumption and environmental emissions. When the pulverized coal is injected into the BF through blowpipes and tuyeres, the coal is a source of heat and a reductant, because of the reactions of devolatilization, gasification, and combustion as well as the formation of unburned char.
Pulverized fuel – It consists of finely ground coal or other combustible material, which can be burned as it issues from a suitable nozzle, through which it is blown by compressed air. Pulverized fuel increases the surface area for combustion, leading to higher thermal efficiency and faster combustion rates.
Pulverized fuel ash – It is the solid material extracted by electrostatic and mechanical means from the flue gases of furnaces fired by pulverized coal. It is also known as fly-ash.
Pulverized fuel firing – It involves grinding of the fuel into fine particles and spraying them into the combustion chamber for efficient burning.
Pump – It is a device which moves fluids (liquids or gases), or sometimes slurries, by mechanical action, typically converted from electrical energy into hydraulic or pneumatic energy. Mechanical pumps serve in a wide range of applications.
Pump and treat – It is a common method for cleaning up groundwater using pumps to bring polluted groundwater to the surface where it can be treated by different methods.
Pump body – It is also known as the pump housing or casing. It is the main structural component of a pump which encloses the internal parts, such as the impeller, and creates the sealed volume through which the fluid passes. It supports the operational components, maintains the necessary pressure and sealing against the external environment, and its structure is designed to withstand internal pressures and provide a path for the fluid to flow from the inlet to the outlet.
Pump characteristic – It is the performance relationship between the flow rate and the pressure (or head) developed by a pump at a given speed, frequently represented by a graphical plot called a pump curve. This performance is detailed by curves showing how head, efficiency, power consumption, and ‘net positive suction head (NPSH) needed vary with different flow rates, providing important data for selecting and operating the correct pump for a specific system.
Pump data sheet – It is a comprehensive document which compiles all critical information about a pump, including its operating conditions (flow, pressure, fluid properties), design specifications, mechanical details, and materials of construction, to enable the selection, specification, and procurement of a pump which meets specific application requirements. It serves as a standardized technical document used to communicate requirements to pump vendors, ensuring the selected pump is appropriate for the process and reliable for its service life.
Pump design – It is the systematic process of creating pumps to move fluids efficiently by applying principles of fluid dynamics and mechanical design. This process involves determining the pump’s specifications to match the needed flow rate and pressure for a specific application. Engineers consider several factors, such as the fluid properties, desired output, and energy efficiency, to select or develop the appropriate pump type, which can include centrifugal or positive displacement designs.
Pump displacement – It is the theoretical volume of fluid a pump moves per cycle, revolution, or stroke. It quantifies the quantity of fluid trapped and transferred by the pump’s internal mechanisms, like pistons or gears, per action of the pump shaft. This metric is crucial for calculating a pump’s theoretical flow rate (displacement multiplied by speed) and understanding its volumetric efficiency.
Pump down time – It is the time of evacuation.
Pumped fluid – It is a liquid or a gas which a pump moves from one location to another, or pressurizes, to achieve a desired outcome. The properties of the pumped fluid, such as its viscosity, specific gravity, cleanliness, and corrosiveness, influence considerably the pump’s design, operation, efficiency, and wear.
Pumped-hydro plant – It is also called pumped storage hydropower plant. It is a hydroelectric energy storage system which uses two water reservoirs at different elevations to store and generate electricity on demand. During low electricity demand, excess energy pumps water from a lower reservoir to an upper one, while during high demand, the water is released downhill through turbines to produce power. Pumped-hydro plant acts as a large-scale battery, storing potential energy in the form of elevated water, making it the widely used form of utility-scale energy storage.
Pumped liquid – It is a liquid being transported or moved by a pump from one point to another, frequently increasing its pressure. The characteristics of the pumped liquid, such as its specific gravity, viscosity, temperature, cleanliness, and vapour pressure, considerably affect the pump’s performance, efficiency, and longevity.
Pumped product – It refers to the specific material or substance being transported through a pump, characterized by its unique properties which influence the selection of the pump type and operational parameters. These properties are critical for ensuring the pump meets process requirements and maintains product quality during transportation.
Pumped-storage hydroelectricity – It is a grid energy storage system that pumps water uphill for later use by a hydroelectric generator plant.
Pumped storage hydropower – It is a type of hydroelectric energy storage functions like a giant rechargeable battery, using two reservoirs at different elevations to store and generate electricity. During periods of low electricity demand, surplus power is used to pump water from the lower reservoir to the upper one. When demand rises, the stored water is released back down through turbines to generate electricity, providing grid stability and storing renewable energy.
Pumped storage hydropower system – It is a large-scale energy storage technology whichacts like a giant battery using two water reservoirs at different elevations. During low electricity demand, surplus power pumps water from a lower reservoir to a higher one, storing potential energy. During high demand, this water is released, flowing through a turbine to generate electricity, balancing the grid, and integrating variable renewable energy sources.
Pump efficiency – It is a measure of how well a pump converts input power (normally mechanical power from a motor) into useful hydraulic power to move fluid. It is calculated as the ratio of the hydraulic power output to the shaft power input, expressed as a percentage. Higher efficiency indicates that a higher portion of the input energy is converted into fluid motion, with less energy lost to friction, heat, or other inefficiencies. The general formula for pump efficiency is ‘pump efficiency = (hydraulic power output / shaft power input) ×100 %.
Pump energy – It refers to the total mechanical energy input from a prime mover to a pump’s shaft, which the pump then converts into hydraulic energy to move and increase the pressure or potential energy of a fluid. This energy is delivered over time, so the total energy is calculated by multiplying the pump’s power (rate of energy transfer) by the duration of operation.
Pump flow – It refers to the volume or mass of fluid a pump moves per unit of time. It is also known as the flow rate. It is a critical specification which defines the pump’s capacity and is measured in different units like cubic meters per hour, litres per second, or gallons per minute. This rate is a result of the pump’s proper functioning, which creates pressure to move the fluid through the system along the path of least resistance.
Pump head – It is a measure of the energy per unit weight which a pump imparts to a fluid, representing the total vertical height the pump can lift the fluid against gravity. It is expressed in units of length (meters) rather than pressure, signifying the pump’s capacity to overcome static lift, fluid friction, and pressure differences. The total head needed for a system is the sum of its geodetic head, pressure head, and friction head.
Pump-house – It is also known as a pumping station. It is a structure which houses pumps and their associated equipment, used to move fluids from one location to another. These buildings are important components of several industrial facilities and systems, including water supply and treatment, drainage, and pumped-storage hydroelectricity installations etc.
Pumping action – It is the mechanical process by which a device, such as a pump, creates flow by alternately increasing and decreasing the volume of a chamber to create suction and discharge for a fluid or particles. This mechanism is seen in positive displacement pumps, where a piston moves within a cylinder, and also in laser systems, where it describes the process of raising particles from a lower to a higher energy state, frequently optically or electrically.
Pumping aid – It is an admixture used in concrete to improve its lubricating properties and reduce segregation, hence facilitating smoother flow and decreasing pumping pressure during the transport of concrete through pipelines.
Pumping configuration – It refers to the arrangement and performance characteristics of pumps within a system, including their series or parallel operation, to optimize hydraulic balance and meet specific power requirements in liquid pipelines.
Pumping efficiency – In a bearing, it is the ratio of actual oil flow to the maximum theoretical flow for a bearing with a 180-degree oil film operating at an eccentricity ratio of unity.
Pumping impeller – It is the rotating component within a pump, normally a centrifugal pump, which uses vanes or blades to impart mechanical energy to a fluid. As the impeller spins, it draws fluid into its centre (the eye) and accelerates it outward. This increase in fluid velocity, as per Bernoulli’s principle, is then converted into pressure within the pump casing, generating flow and discharging the fluid.
Pumping loss – It refers to the energy or power needed to move fluids through a system by overcoming resistance from pressure differences, friction, and flow restrictions, such as the work a piston does to draw intake air and expel exhaust gases in an internal combustion engine, or the parasitic power a pump uses to move a liquid. These losses reduce the net useful work output of the system and are influenced by factors like fluid viscosity, flow velocity, pipe design, and throttle position.
Pumping performance – It describes how effectively a pump system moves a fluid by quantifying its head (pressure), flow rate, and power consumption at different operating conditions, as represented by a pump performance curve. Key performance aspects include pump efficiency, which is the ratio of useful power output to total power input, and the location of the Best Efficiency Point (BEP), where the pump operates most efficiently.
Pumping plant – It is a facility consisting of pumps, drivers (motors or engines), and associated power and plumbing systems designed to move water or other fluids from one location to another at a specific flow rate and pressure, frequently to overcome gravity or manage water levels. These systems are important for applications like delivering water to consumers, and managing sewage, with energy efficiency and performance being key considerations in their design.
Pumping power – It is the mechanical power needed to operate a pump to impart energy to a fluid, increasing its pressure and / or velocity. It is calculated as the product of the total pressure differential created by the pump (or pressure head) and the volume flow rate of the fluid, adjusted by pump efficiency to determine the actual energy input needed from the motor or engine.
Pumping ring – It is a component within a mechanical seal that, acting like a small impeller, uses centrifugal force to circulate a barrier fluid to lubricate the seal faces and dissipate heat, ensuring the seal’s continued operation and longevity. These rings can be axial or radial in design, differing in how the fluid enters and is directed, and are crucial for systems operating under high temperatures or needing continuous fluid circulation for effective sealing.
Pumping speed – It is the volumetric flow rate of gas through a vacuum pump’s inlet port, measured at a specific pressure, and indicates the pump’s transportation capacity for gas in volume per unit time (e.g., cubic-meters per hour or litres per second). It quantifies how much gas the pump can remove, but it is different from the pump’s throughput, which is the actual mass or volume of gas moved. Pumping speed is an intrinsic characteristic of the pump and changes with pressure, with the effective speed also affected by the conductance of the system connecting the pump to the chamber being evacuated.
Pumping station – It is a facility containing pumps and associated equipment used to transport liquids by increasing their pressure or raising them to a higher elevation, overcoming gravitational forces or pipeline resistance. It serves critical infrastructure roles in systems for water supply, sewage collection, drainage, storm water, industrial processes, and power generation by ensuring reliable fluid flow and distribution where gravity alone is not sufficient.
Pumping system – It is a mechanical setup which uses one or more pumps to add energy to a fluid, thereby moving it from one point to another, often against gravity or friction, by creating pressure. These systems are critical for transferring liquids or gases to desired locations, circulating them, or maintaining necessary pressure levels for different applications, from simple water supply to complex industrial processes. Key considerations in designing and operating such systems include the fluid’s characteristics, the needed flow rate and total dynamic head, and the overall system efficiency.
Pumping test – It is a field experiment where groundwater is pumped from a well at a controlled rate, and the resulting water level changes, or drawdown, are measured over time in observation wells and the pumped well itself. The primary purpose is to determine the hydraulic properties of an aquifer, such as its transmissivity (ability to transmit water) and storativity (ability to store water), which are crucial for evaluating well capacity, managing groundwater resources, and designing dewatering systems for construction projects.
Pumping time – It is the estimated duration from the start of mixing cement until the cement is in place, needing the cement slurry to remain liquid long enough for effective pumping.
Pumping turbine – It is more precisely called a reversible pump-turbine. It is a hydraulic machine which can operate in two distinct modes namely as a pump to move water or fluids, and as a turbine to generate power from falling water. This dual function is utilized in pumped hydroelectric storage (PHES) facilities to store energy by pumping water uphill and then generate electricity when that water flows back down through the turbine.
Pumping unit – It is the assembly comprising the pump, transmission device (coupling), driver (motor), and auxiliary systems (such as lubrication and cooling systems) necessary for its operation. It is important to consider all these components during troubleshooting and maintenance to ensure effective performance.
Pump inlet – It is also called the suction port. It is the port on a pump where fluid enters the pump. It creates a low-pressure area or vacuum, drawing in fluid from a source which is under higher atmospheric pressure. A continuous, uninterrupted flow of fluid is needed at the inlet to prevent damage or failure, which can result from insufficient inlet pressure.
Pump inlet pressure – It is also called suction pressure. It is the pressure of the fluid available at the pump’s inlet port, measured where the fluid enters the pump. It can be positive or negative (a vacuum) and is crucial for determining the ‘net positive suction head available (NPSHa), ensuring the pump’s proper function, and preventing issues like cavitation or damage from insufficient fluid supply.
Pump intake pressure – It is also known as pump inlet pressure or suction pressure. It is the pressure of the fluid as it enters the pump’s suction side. This pressure, which can be positive or negative (vacuum), represents the available energy in the fluid before the pump begins its work of increasing the pressure. Maintaining adequate intake pressure is important for preventing pump damage and ensuring efficient operation, as insufficient pressure can lead to issues like dry running or excessive wear.
Pump-out tubulation – It is a tube extending from an evacuated device through which gas is pumped and which is normally permanently sealed off after the device has been evacuated. It is sometimes called exhaust tubulation.
Pump performance – It defines how a pump’s hydraulic head (pressure) and flow rate change with its energy consumption and efficiency, normally represented on a pump performance curve. This curve, provided by the manufacturer, shows the pump’s ability to deliver flow under varying pressures, helping to identify the optimal operating point (best efficiency point, or BEP) and ensure suitability for a system.
Pump piston – It is the movable disk or cylinder within a pump’s cylinder which creates suction and discharge by alternately increasing and decreasing the volume of the cylinder. This reciprocating motion, driven by a pump rod and connected to a mechanism like a cam or crankshaft, is fundamental to a piston pump’s operation, enabling it to generate pressure and move fluids or gases.
Pump power – It refers to the rate at which mechanical energy is input into a pump (pump input power or brake horsepower (BHP)) and the useful hydraulic energy it delivers to the fluid (pump output power or water horsepower (WHP)). The difference between these is because of the energy losses within the pump, with pump efficiency being the ratio of output power to input power. Factors like fluid properties (density, viscosity) and operating conditions (flow rate, pressure) all influence the needed pump power.
Pump size – It refers to the dimensions and capacity of a pump, which are determined by factors such as the specified requirements, speed, geometry, and number of stages necessary for its intended application.
Punch – It is the male part of a die, as distinguished from the female part, which is called the die. The punch is normally the upper member of the complete die assembly and is mounted on the slide or in a die set for alignment (except in the inverted die). In double-action draw dies, the punch is the inner portion of the upper die, which is mounted on the plunger (inner slide) and does the drawing. Punch is also the act of piercing or punching a hole. It is also referred to as punching. It is the movable tool which forces material into the die in powder molding and most metal forming operations. It is the movable die in a trimming press or a forging machine. It is the tool which forces the stock through the die in rod and tube extrusion and forms the internal surface in can or cup extrusion.
Punch diameter – It is the measurement of the diameter of a punch used in machining, which can show small deviations from its intended size, affecting the accuracy of the holes produced in the material being punched.
Punched card – It is a stiff paper-based medium which uses the presence or absence of holes in predefined positions to represent digital data and instructions, historically serving as a main method for data input into early mechanical and electronic computers and for controlling automated machinery, with early applications including Jacquard looms and Herman Hollerith’s tabulating machines for census data.
Punching – It is the die shearing of a closed contour in which the sheared-out sheet metal part is scrap. It is producing a hole by die shearing, in which the shape of the hole is controlled by the shape of the punch and its mating die. Multiple punching of small holes is called perforating.
Punching and shearing machine – It is a multi-function tool used to cut, punch, bend, and shape metal. It is signed to handle tough fabrication tasks automatically. These machines replace manual cutting and drilling methods, offering faster and cleaner results.
Punching shear – It is a failure mode in concrete slabs and foundations where a concentrated load, such as from a column, causes the slab to rupture and form a cone-shaped crack, allowing the load to ‘punch’ through the structure. This is a brittle failure, meaning it can happen suddenly and without warning, making it a critical design consideration to prevent catastrophic collapse. Engineers prevent punching shear by increasing slab depth, adding drop panels or column capitals, increasing column size, or providing shear reinforcement around the loaded area.
Punching shear test – It is a method which is used to determine the through-thickness shear strength of sheet material which involves blanking a disk out of flat strip using a simple punch-and-die method. It is also known as blanking shear test.
Punchout machine – It is a machine used to force the entire sand and casting contents from the mould box in one motion, without the use of vibration.
Punch press – In general, it is a mechanical press. In particular, an end wheel gap-frame press with a fixed bed, used in piercing. It is a machine tool which uses a shaped punch and die to cut holes, shapes, and notches in sheet metal, as well as perform bending and forming operations through the application of high force. These presses are highly versatile, found in several sizes from small to massive industrial machines, and are essential in industries for high-volume production of standardized parts.
Punch radius – It is the radius on the end of the punch which first contacts the work. It is sometimes called nose radius. Punch presses are used for bending, flanging, and hemming low-carbon steel when production quantities are large, when close tolerances must be met, or when the parts are relatively small.
Pungent odour – It is a strong and sharp smell which is easily detectable at relatively high concentrations, frequently associated with compounds like ammonia, which is recognized by humans above 50 parts per million, Such odours can act as warning signs and are commonly linked to different sources, including industrial wastes and industrial activities.
Purchase order (PO) – It is a commercial document issued by a buyer to a seller, indicating the products or services the buyer wishes to purchase, along with the quantity, agreed price, and other relevant details. It essentially serves as a formal offer from the buyer to the seller, and once accepted, becomes a legally binding contract.
Purchase management – It is based on seven principles which are also known as 7 ‘Rs’. These seven principles are (i) purchase of material at right quality, (ii) purchase of material in right quantity, (iii) purchase of material from the right source, (iv) purchase of material at the right price, (v) delivery of material at the right place, vi) delivery of material at the right time, and (vii) delivery of material with the right mode of transport.
Purchase managers – They are senior professionals responsible for overseeing the procurement of goods, services, and supplies for the organization. They ensure these are acquired efficiently, at the best prices, and at the right time to support organizational operations. Their role involves developing purchasing strategies, evaluating and negotiating with suppliers, managing contracts and vendor relationships, controlling inventory, and managing budgets to optimize costs and maintain quality.
Purchase procedures – These are the rules and regulations that define the organizational purchasing activities and keep purchasing legal and appropriate. These procedures also describe the ethics that purchasing personnel in the organization must embrace. These procedures are evolved to streamline the purchasing activities in the organization and remove adhocism while adhering to current regulatory policies of the land.
Purchase requisition – It is a document within an organization to enable the creation of a request to purchase goods or services. Employees simply need to fill out the purchase requisition to start the process of purchasing, which starts with approval. The procurement team within the enterprise then tries to secure the right deal, for each category and with each supplier. However, the use of a purchase order management system can efficiently and effectively manage the purchasing part of the process and drastically reduce the workload.
Purchase specification – It is a detailed document or list which clearly describes the exact requirements for a product or service a buyer wants to acquire, covering quality, size, performance, and other factors to ensure the purchased item meets the buyer’s needs and is comparable across multiple suppliers. It serves as a guide for purchasing personnel and a fixed set of criteria for suppliers, ensuring clarity on what is expected and facilitating fair bidding and consistent quality control.
Purchasing approaches – Considering the operations of the organization, purchasing can have different approaches. These approaches are (i) tender purchasing (can be open, global, limited, or single tender), (ii) negotiated purchasing, (iii) contracting, (iv) rate contract, (v) automatic procurement or minimum stock purchasing, (vi) blanket order, (vii) repeat ordering, (viii) spot purchasing, (ix) risk purchasing, (ix) forward purchasing, (x) speculative purchasing, (xi) reciprocity, and (xii) e-procurement.
Pure aluminum – It a soft, silvery-white, ductile and non-magnetic metal which belongs to the boron group and has atomic number 13. To be considered pure aluminum, the metal needs to consist of 99 % aluminum. It has high electrical and thermal conductivity, and is resistant to oxidation. It is a relatively low strength, extremely flexible metal with virtually no structural applications.
Pure copper – It is a high-purity grade of copper, typically with a minimum copper content of 99.3 % or higher, defined as having a minimum of 99.95 % copper by some standards, with oxygen content below 10 parts per million for specialized applications like ‘oxygen-free’ grades. It is a reddish-brown, malleable, and ductile metal known for its excellent electrical and thermal conductivity, which are maximized by minimizing impurities and used in applications like electrical wires and components where these properties are important.
Pure ductile tearing – It consists of microscale ductile crack propagation by micro-void coalescence on the plane of maximum normal stress.
Pure fluid – It is a fluid which consists of a single type of molecule or atom and has a homogeneous chemical composition throughout, such as pure water or pure methane. In engineering and thermodynamics, a substance is considered a pure substance even if it exists in multiple phases (solid, liquid, or gas) or a mixture of phases, as long as its chemical makeup remains uniform. For example, a mixture of liquid water and water vapour in equilibrium is still considered a pure substance.
Pure gas – It is a gaseous substance composed of only one chemical component, such as a single element (like pure neon) or a single compound (like pure carbon di-oxide), and contains a very high level of purity, with minimal or no impurities like moisture or other gases. These high-purity gases are manufactured to specific grades, such as 99.999 % pure, to ensure that even tiny quantities of contaminants do not interfere with industrial, or scientific applications.
Pure iron – It is a common metal but it is mostly confused with other materials such as steel and wrought iron. All these materials vary in composition. The carbon content of pure iron makes it unique and different from the other metals and ferrous alloys. The carbon content in pure iron is always less than 0.008 %. Wrought iron has a higher carbon content of up to 0.5 %. This shows how less the impurities are in the pure iron. Pure iron has a body centred cubic (bcc) structure at ordinary temperatures and is ferro-magnetic with a curie temperature of 768 deg C. The magnetic and non-magnetic forms are normally referred to as alpha-iron and beta-iron respectively. Iron changes to the face-centered cubic (fcc) form (gamma-iron) on heating to 910 deg C and then back to the body centred cubic structure form (delta-iron) at 1,394 deg C.
Pure liquid – It is a liquid composed entirely of one type of molecule or chemical compound, meaning it contains no impurities or other substances. This uniformity gives it consistent physical properties, like a fixed melting and boiling point, and a homogeneous composition throughout its volume. Common examples of pure liquids include distilled water and certain hydrocarbons like n-hexane.
Pure metals – These are elements which consist of a single type of atom. They have a highly ordered atomic structure, which makes them relatively soft and malleable. Examples of pure metals include gold, silver, copper, and aluminum. Pure metals are known for their high electrical and thermal conductivity, as well as their lustrous appearance.
Pure substance – It is a material with a uniform and definite composition, consisting of only one type of particle (either an element or a compound) which cannot be broken down into simpler components by physical means. Elements are substances made of only one type of atom, such as iron (Fe), while compounds are formed when different elements chemically bond in a fixed ratio, such as water (H2O).
Pure tension – It occurs when a body is subjected to tensile forces which only pull it apart in one direction, causing stretching and thinning in the perpendicular directions, but no shear or bending stresses. This leads to a specific stress state where the fracture plane is perpendicular to the tensile force.
Pure torque – It is also called a pure moment or moment of force. It is a rotational force which causes an object to twist or spin without causing it to move in a straight line. It is effectively a couple (two equal and opposite parallel forces separated by a distance ) creating a turning effect with no net translational force.
Pure torsion – It is the condition of a structural member, typically a circular shaft, which is subjected only to a twisting moment (torque), with no other forces like bending moments or axial loads acting on it. This occurs when equal and opposite couples are applied to the shaft’s ends, causing it to twist. The resultant twisting moment is constant along the shaft’s length, and the material experiences shear stress and shear strain as it deforms into a parallelogram from its original rectangular section.
Pure water – It is defined as water which has been extensively treated to remove impurities, achieving an extremely low level of contaminants (frequently measured in parts per billion or trillion) to meet the stringent requirements of industrial, or technical applications. This definition emphasizes its high purity, characterized by low conductivity, minimal salt concentration, and the absence of particles, and it highlights the use of advanced purification processes like reverse osmosis and ultrafiltration to produce it.
PUREX process – PUREX is acronym for plutonium–uranium redox extraction. It is a widely used hydro-metallurgical (wet chemical) technique for chemically separating uranium and plutonium from spent nuclear fuel dissolved in nitric acid. It uses liquid-liquid extraction with tributyl phosphate (TBP) in an organic solvent (like dodecane) to selectively extract uranium and plutonium from the highly acidic solution, leaving behind waste products like fission products and minor actinides. The recovered uranium and plutonium can then be reused to fabricate new fuel, such as MOX (mixed-oxide) fuel.
Purification process – It is a method or act of making something pure by removing unwanted or harmful substances (impurities) from it. This process aims to separate a target substance from foreign elements, contaminants, or pollutants to isolate the desired product in a cleaner form. Purification is a fundamental concept used in various fields.
Purity – It is the degree to which a material, substance, or signal is free from unwanted impurities or contaminants, which can negatively affect its properties or performance in a specific application. It is frequently expressed as a percentage and is important for achieving desired physical characteristics, chemical properties, and functional performance in different fields.
Purge – It is to introduce air into the furnace and the boiler flue passages in such volume and manner as to completely replace the air or gas-air mixture contained therein.
Purge gas – It is an inert gas, like nitrogen, used to remove unwanted or reactive gases from a system. This process, called purging, creates a safe, controlled environment for sensitive operations such as chemical reactions, welding of specific metals, or maintaining safety in flare systems and vessels. The goal is to prevent oxidation, explosions, or other undesirable reactions by displacing the original atmosphere with a non-reactive one.
Purging – It refers to the process of removing unwanted substances, like gases, contaminants, or residues, from a system, frequently to prevent oxidation, contamination, or other undesirable reactions. This is crucial in several metal-working processes, such as steelmaking, welding, casting, and extrusion, to ensure material purity, prevent defects, and maintain product quality.
Purging process – It is the systematic removal of unwanted substances (such as hazardous gases, impurities, or air) from a closed system, vessel, or enclosure by introducing a purge fluid, frequently a non-combustible inert gas like nitrogen, to displace the contaminants. The primary goals are to prevent fires and explosions by creating a safe, inert atmosphere, to clean equipment before maintenance or production, or to eliminate moisture and other contaminants from the system.
Purifiers, flux – These consist of several materials which are added to molten metals and alloys for the purpose of removing impurities, and gases etc.
Purity – It refers to the degree to which a substance is free from impurities. It is the measurement of the quantity of impurities found in a sample.
Purlin – It is a horizontal structural member, typically a beam or bar, which supports the roof deck or sheathing by transferring the roof’s load to the building’s main framework, such as walls or rafters. Purlins are installed parallel to the building’s ridge or eave and are necessary components in pre-engineered buildings (PEBs), providing support for large roofs and improving overall structural stability.
Purple hydrogen – It is also called yellow hydrogen. It is produced by water electrolysis using energy from nuclear power.
Push and pull type pickling lines – These types of lines are used normally for small and medium production capacities. In these lines preferred thickness of hot strip is more than 1.5 millimeters. In these types of lines, the strip is neither welded nor stitched but is pushed or pulled through the line strip by strip. The advantage of the push and pull pickling line is its high flexibility combined with high productivity at low investment costs. Cost-intensive equipment, like welding machines, loopers, and bridle rolls, is not required. The shallow pickling tank design ensures high turbulence and reduced pickling time.
Push-bar conveyor – It is an endless-chain conveyor in which crossbars propel or lift the load by direct engagement or push the load over rollers or a flat surface.
Push bench – It is an equipment which is used for drawing moderately heavy-gauge tubes by cupping sheet metal and forcing it through a die by pressure exerted against the inside bottom of the cup.
Push bench process – It is a method for producing seamless pipes and tubes. It involves piercing a heated billet to create a thick-walled hollow shell, then elongating and reducing the wall thickness of the shell by pushing it through a series of dies with a mandrel bar inside. This process is used to manufacture a wide range of pipe sizes, often with a downstream stretch-reducing mill to achieve different dimensions.
Push-button – It is a simple switch mechanism to control some aspect of a machine or a process. Buttons are typically made out of hard material, normally plastic or metal. The surface is normally flat or shaped to accommodate the human finger or hand, so as to be easily depressed or pushed. Buttons are very frequently biased switches, although several un-biased buttons (because of their physical nature) still need a spring to return to their un-pushed state.
Push-button station – It is an electrical mechanism which triggers and operates a magnetic starter.
Pusher – It is an air-powered device which is used for moving products between conveyor lines and chutes.
Pusher arm – It is a mechanical arm in a conveyor system which is used to push or divert materials, necessitating periodic inspections for proper operation, alignment, and overall functionality.
Pusher device – It is a mechanical device in a conveyor system which is used to push materials off the conveyor, needing periodic checks for proper functioning and alignment.
Pusher furnace – It is also called pusher type furnace. It is a type of continuous furnace in which parts to be heated are periodically charged into the furnace in containers, which are pushed along the hearth against a line of previously charged containers hence advancing the containers toward the discharge end of the furnace, where they are removed.
Pusher machine – It is a machine with operates in coke oven battery. The pusher machine travels along the length of the battery and carries out various functions such as (i) remove and replace coke oven doors, (ii) push out hot coke from the oven, (iii) open and close leveller bar doors, (iv) level the coal charge in the oven, (v) clean doors, frame and flash plates, (vi) degraphitize the oven ceiling, and (vii) remove the coke spillage. The pusher machine is located at the coke oven battery side and is normally designed for the single spot operation. The drives of machine can be hydraulic or electro-mechanical. Operator’s cabin, and the hydraulic and electronic equipment cabins are normally equipped with air-conditioners. The main functional units of the coke pusher machine are (i) travelling mechanism, (ii) pushing mechanism, (iii) door latch unscrewing mechanism, (iv) door snatching mechanism, (v) door turning mechanism, (vi) travelling mechanism for door extractor installation, (vii) door cleaning mechanism, (viii) door frame and flash plate cleaning mechanism, (ix) levelling mechanism, (x) leveller bar door opening mechanism, (xi) coal charge spillage collecting system, (xii) coke spillages collecting device with quenching system, (xiii) degraphitizing mechanism.
Pusher sorter – It is a sorting device in a conveyor system which uses pushers to divert materials onto different paths, necessitating regular inspections for proper operation and alignment.
Pusher type furnace – In the pusher type of furnace, cold steel stock is pushed forward with the help of pushers at the charging side. Earlier, these furnaces were designed for heating billets or smaller sections of blooms. The hearth of earlier furnaces was short in length and sloped downward longitudinally towards the discharge end in order to permit easy passage of steel stock through the furnace. Presently pusher furnaces are longer with hearths of around 25 meters to 30 meters in length. These furnaces are equipped with either top firing or top and bottom firing. These furnaces normally have three zones namely (i) preheating zone, (ii) heating zone, and (iii) soaking zone. Multiple zone furnaces such as five zone slab reheating furnaces have also been designed and operated. In pusher type furnace, cold steel stock can be charged in such furnace either from the end or through a side door. In either case, the steel stock is moved forward by pushing the last piece charged with a pusher at the charging end. With each pushing of the cold steel stock against the continuous line of material, a heated piece is discharged at the discharge end either by gravity through an end door upon a roller table feeding the rolling mill, or pushed through a side door to the mill roller table by suitable manual or mechanical means, or withdrawn through the end door by a mechanical extractor.
Pusher-type seal – It is a mechanical seal in which the secondary seal is pushed along the shaft or sleeve to compensate for face wear.
Push-over analysis – It is a static, nonlinear procedure used to estimate a structure’s seismic performance by incrementally applying a gravity load and increasing lateral loads until a predefined displacement or collapse state is reached. This process reveals a pushover curve, which plots base shear against roof displacement, showing the building’s behaviour beyond its elastic limit, such as cracking, yielding, and crushing. The analysis helps identify potential weaknesses, evaluate seismic resistance, and verify if performance objectives for new or existing structures are met.
Push–pull converter – It is a converter with two sets of primary switching elements so that the transformer primary voltage can be reversed on each cycle.
Push-pull effect – It consists of factors which push from the initial state towards better opportunities and factors which pull because of their attractive characteristics towards the future state of organization. Push factors are things which are unfavourable while the pull factors are things that attracts.
Push-pull fatigue testing – It is also known as axial fatigue testing. It is a type of mechanical test which evaluates a material’s resistance to failure under repeated cycles of tension and compression (push and pull). This testing method simulates the fluctuating stresses materials experience in real-world applications, allowing engineers to determine how many cycles a material can withstand before fracturing.
Pushrod – It is a a rod actuated by a cam to open or close a valve of an internal combustion engine.
Push switch – It is a device which closes or opens an electrical circuit when pushed.
Push welding – It is spot or projection welding in which the force is applied manually to one electrode, and the work or backing plate takes the place of the other electrode.
p-value – p-value is the probability of obtaining sample results as least as unfavourable to the null hypothesis as is observed if the null hypothesis is true. The probability value (p-value) of a hypothesis test is the probability of getting a value of the test statistic as extreme, or more extreme, than the one observed, if the null hypothesis is true. Small p-values suggest the null hypothesis is unlikely to be true. The smaller it is, the more convincing is the evidence to reject the null hypothesis. In the pre-computer era, it is common to select a particular p-value, (frequently 0.05 % or 5 %) and reject H0 if (and only if) the calculated probability is less than this fixed value. Now it is much more common to calculate the exact p-value and interpret the data accordingly.
PV product – It refers to the product of pressure (P) and specific volume (V) of a fluid, representing the work needed to introduce the fluid into a system without changing its volume.
PVC belt – It is a type of conveyor belt which made from polyvinyl chloride (PVC) material which is known for its versatility and resistance to wear. Periodic inspections are essential to assess wear and overall belt condition.
PVC impregnated – It is a textile carcass impregnated with PVC compound (plastisol).
PVC insulated electric power cables – PVC stands for poly-vinyl chloride. These cables are normally used up to and including 11 kilovolts installations. Insulation material used is PVC and conductors are made from electrical purity aluminum or copper. For giving flexibility to the conductors of cables are stranded. These cables are used where combination of ambient temperature and temperature rise because of load results in conductor temperature not exceeding 70 deg C under normal operation and 160 deg C under short circuit conditions. Different cores in a cable are identified by the colours of PVC insulation. Accepted colour codes for PVC insulated cables are for (i) single core – red, yellow, blue, or black, (ii) tin core – red and black, (iii) three core – red, yellow, and blue, (iv) four core – red, yellow, blue, and black, and (v) five core – red, yellow, blue, black, and light grey. In 3.5 core cables, the three main cores are red, yellow, blue for phases and reduced core is black for neutral. Red, yellow, blue colours represent phase ‘R’, ‘Y’, ‘B’ phases and black colour represents neutral ‘N’ phase. For cables of voltage grade up to and including 6.6 kilovolts, method of core identification is (i) different colouring of the PVC insulation, (ii) coloured strips applied on the cores, or (iii) by numerals (1,2,3), either applying numbered strips or by printing on the cores. For cables of voltage grade of 6.35 kilovolts / 11 kilovolts, method of core identification is (i) coloured strips applied on the cores, or (ii) by numerals (1,2,3), either by applying numbered strips or by printing on the cores.
PV factor – It is the product of bearing pressure and surface velocity traditionally expressed in terms of is pascal x metre per second (Pa.m/s).
P-X diagram – It is a two-dimensional graph of the isothermal phase relationships in a binary system. In this graph, the coordinates of the graph are pressure and concentration.
P-X projection – It is a two-dimensional graph of the phase relationships in a binary system produced by making an orthographic projection of the phase boundaries of a P-T-X diagram upon a pressure concentration plane.
p-Xylene – It is also known as para-xylene. It is a colourless, flammable liquid with a sweet odour. It is a type of xylene isomer. It is characterized by having two methyl groups attached to a benzene ring in a para (1,4) position. A key use of p-xylene is as a raw material in the production of terephthalic acid and dimethyl terephthalate, which are used to make polyester fibres and resins.
Pycnometer – It is a precise laboratory instrument, typically a glass flask with a precisely known volume, used to measure the density of liquids or the specific gravity of solids, especially fine-grained materials like soil or aggregates. Its stopper frequently has a fine capillary tube to allow for accurate filling and precise volume determination, making it a fundamental tool for calculating soil properties such as void ratio and water content.
Pylon – It is a steel structure used in stackers and reclaimers. It is a support tower structure for suspension bridges or highways. In case of power transmission, it is a large vertical steel lattice tower-like structure used for supporting high-tension overhead power lines.
Pyramid – It is a polyhedron formed by connecting a polygonal base and a point, called the apex. Each base edge and apex form a triangle, called a lateral face. A pyramid is a conic solid with a polygonal base.
Pyramidal hopper – It is a hopper in a conveyor system with a pyramidal shape. It is used for efficient material feeding. Regular inspections are necessary to prevent blockages and ensure proper material flow.
Pyramidal plane – In non-cubic crystals, it is a plane which intersects all three axes.
Pyramidal slip – It refers to a slip mechanism in crystalline materials, particularly observed in zirconium, where slip occurs on pyramidal planes with (c + a) type Burgers vectors, enabling deformation at high temperatures.
Pyramiding – It is the use of increased buying power to increase ownership arising from price appreciation.
Pyramid of incidents – Pyramid of incidents is also known as Heinrich’s triangle or Bird’s triangle. It provides a theoretical view of the industrial accident prevention. It shows a relationship between serious accidents, minor accidents, and near misses.
Pyridine – It is a heterocyclic organic compound with the chemical formula C5H5N. It is a colourless, flammable liquid with a distinct, unpleasant odour. It is structurally similar to benzene but with one CH group replaced by a nitrogen atom. Pyridine is a weak base and mixes with water. It is widely used as a solvent and in the synthesis of several chemicals, and industrial products. Pyridine has a six-membered ring containing five carbon atoms and one nitrogen atom. It is an aromatic compound, meaning it has a stable, cyclic structure with delocalized electrons.
Pyrite – It is a yellow iron sulphide mineral, normally of little value. It is sometimes referred to as ;fool’s gold’.
Pyro-hydrolysis – Pyro-hydrolysis is a process where the spent pickle liquor is thermally decomposed in order to convert the spent pickle liquor back into hydrochloric acid and iron oxide. This process is carried out at a very high temperature along with water vapour and oxygen. The spent pickle liquor is pumped into the pyro-hydrolysers which convert the ferrous chloride (FeCl2) into components of ferric oxide (Fe2O3) and hydrochloric acid. Pyro-hydrolysis plants are very energy intensive, mainly because a large amount of fuel combustion is needed to evaporate the metal chloride solution and to heat the roaster contents.
Pyrolysis – It is the process of thermal decomposition of materials at high temperatures, frequently in an inert atmosphere without access to oxygen. Pyrolysis is normally used in the treatment of organic materials. With respect to fibres, the thermal process by which organic precursor materials, such as rayon, polyacrylonitrile (PAN), and pitch, are chemically changed into carbon fibre by the action of heat in an inert atmosphere. Pyrolysis temperatures can range from 800 deg C to 2,800 deg C, depending on the precursor. Higher processing graphitization temperatures of 1,900 deg C to 3,000 deg C normally lead to higher modulus carbon fibers, normally referred to as graphite fibres. During the pyrolysis process, molecules containing oxygen, hydrogen, and nitrogen are driven from the precursor fibre, leaving continuous chains of carbon.
Pyrolysis gas – It refers to the gaseous mixture of volatile organic compounds and inorganic gases produced by the thermal decomposition of organic materials (like biomass, plastics, or waste) in the near-absence of oxygen, which can then be used as a valuable fuel or feedstock. This process, called pyrolysis, breaks down large, complex molecules into smaller, simpler ones, including solid char, liquid oil, and the gas mixture known as pyrolysis gas or syngas.
Pyrolysis gas chromatography – It is an analytical method which involves the rapid, controlled thermal decomposition of solid or liquid materials in an oxygen-free environment to break them into smaller, volatile fragments. These fragments are then immediately analyzed by gas chromatography (GC) and frequently mass spectrometry (MS) to determine the chemical structure and composition of the original material, providing valuable insights for material characterization, and failure analysis.
Pyrolysis mechanism – It describes the specific chemical pathways and bond-breaking events which cause a solid or liquid material to decompose into smaller gaseous, liquid, and solid (char) products when subjected to high temperatures in the absence of oxygen. These mechanisms involve thermal degradation of complex molecules into simpler ones and can include three main types namely random scission, side-group scission, and monomer reversion, with the specific pathway influenced by factors like temperature, heating rate, and the original material’s chemical composition.
Pyrolysis reactor – It is an equipment which facilitates the thermal decomposition of organic materials (like biomass and waste) in an oxygen-free environment at high temperatures (typically 300 deg C to 800 deg C) to produce solid (char), liquid (bio-oil), and gaseous (syngas) products. These specialized systems are designed with features for efficient heat transfer and precise control over conditions like heating rate and temperature, enabling the conversion of waste into valuable energy sources and chemicals.
Pyrolysis treatment – It is the thermo-chemical decomposition of organic materials at high temperatures (e.g., 300 deg C to 900 deg C) in an oxygen-free or inert atmosphere. This irreversible process breaks down complex molecules into simpler products namely a solid char, a liquid oil (bio-oil), and gaseous components (syngas). Pyrolysis treatment is used in waste management and chemical engineering to convert waste into valuable products and fuel, recover energy, and sequester carbon in the form of biochar.
Pyro-metallurgical process – It is a branch of extractive metallurgy which uses high-temperature thermal treatments to extract, refine, and recover metals from ores and waste streams. This process involves a series of physical and chemical changes at temperatures frequently ranging from 500 deg C to 2,000 degrees C, using techniques like roasting, sintering, smelting, and incineration to convert impurities into slag and to vapourize or melt the valuable metals. Pyrometallurgy is widely used for large-scale metal production and recycling, producing pure metals or intermediate compounds for further processing.
Pyro-metallurgy – It is the high-temperature winning or refining of metals.
Pyrometer – It is a device for measuring temperatures above the range of liquid thermometers.
Pyrometric cone equivalent (PCE) – It is the reference number of the pyrometric reference cone which has bent over to the same degree as test pieces of a refractory or the number of the two cones which have bent over, one a little more and one a little less than the test pieces when the cones and the test pieces have been mounted together and heated under specified conditions.
Pyrometric cones – These are also known as Seger cones. These cones are used in ceramic industries to test the refractoriness of the refractory bricks. They consist of a mixture of oxides which are known to melt at a specific narrow temperature range.
Pyrometric reference cone – It is the blunt-tipped skew triangle pyramid with sharp edges, of specified shape and dimensions and of such composition that, when mounted and heated under specified conditions, it bends in a known manner with reference to its heat temperature.
Pyrometry – It is a method of measuring temperature with any type of temperature indicating instruments.
Pyrophoricity – It is a property of certain metals and oxides, particularly those in lower oxidation states, which causes them to spontaneously ignite during or after stabilization. To prevent spontaneous ignition, these pyrophoric components must be fully oxidized. It is the property of a substance with a large surface area to self-ignite and burn when exposed to oxygen or air.
Pyrophoric powder – It is a powder whose particles self-ignite and burn when exposed to oxygen or air, e.g., fine zirconium powder.
Pyrophyllite – It is a hydrous aluminum silicate mineral with the chemical formula Al2Si4O10(OH)2, known for its unique properties like chemical inertness, low thermal and electrical conductivity, high dielectric strength, and a high melting point. These characteristics make it valuable in refractory and ceramic applications, where it is used for its low expansion coefficient, high corrosion resistance, and low bulk density. Pyrophyllite’s distinct crystal structure, similar to talc but with aluminum instead of magnesium, allows it to withstand high temperatures and resist deformation, enabling its use in manufacturing materials like flame-resistant ceramics and high-temperature fillers.
Pyro-shock – It is the dynamic structural shock which occurs when an explosion or impact occurs on a structure.
Pyroxene – It is a group of rock-forming silicate minerals composed of silica tetrahedra in single chains, with the general formula XY(Si,Al)2O6, where ‘X’ and ‘Y’ are metal ions. It is found mainly in igneous and metamorphic rocks, and sometimes in meteorites and lunar rock.
Pyroxenite – It is an ultramafic, intrusive igneous rock composed predominantly of minerals from the pyroxene group, such as clinopyroxenes (like diopside, augite) or orthopyroxenes (like enstatite, hypersthene), frequently with lesser quantities of olivine and other accessory minerals. These rocks are classified by the type and proportion of pyroxenes they contain, such as clinopyroxenite (mostly clinopyroxene) or orthopyroxenite (mostly orthopyroxene).
Pyrrhotite – It is a bronze-coloured, magnetic iron sulphide mineral.
Pythagorean theorem – It states that in a right-angled triangle, the square of the length of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the lengths of the other two sides, frequently called the legs.
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