Pipe and Tubes

Pipe and Tubes

Pipes and tubes (Shown in Fig 1) are long hollow vessels that are used for a variety of purposes often for conveying materials, as a structural component or manufacturing equipment components like conveyor rollers and bearing casing etc.


Fig 1 Pipes and tubes

The main difference between a pipe and a tube is the way the diameter of the pipe or tube is designated. Pipe is normally designated by a “Nominal Pipe Size” based upon the ID (inside diameter) of the most common wall thickness while the tube is designated by the measured OD (outside diameter). As an example a 20 mm steel pipe with 4 mm thickness has an OD of 28 mm while a 20 mm steel tube has an OD of 20mm.

Tubes are often made to custom sizes and may often have a large number of specific sizes and tolerances than pipes. The term tube is also applied to non cylindrical shapes such as square tubes etc. Both pipes and tubes are associated with a level of rigidity and permanence while a hose is usually portable and flexible.

Pipes and tubes are often classified by the material of the pipes. As per this classification pipes and tubes can be classified:

  1. Iron pipe such as cast iron pipe and ductile iron pipe
  2. Steel pipe such as carbon steel pipes, special steel pipes, alloy steel pipes and stainless steel pipes
  3. Type of coating such as galvanized pipe, aluminized pipe and chromium coated pipes etc.
  4. Copper and copper alloy (for example brass) pipes and tubes
  5. Aluminium and aluminium alloy pipes and tubes
  6. Plastic pipes and such as PVC, CPVC, PP, PEX, PB, ABS, HDPE and GRP pipes etc.
  7. Cement, Reinforced concrete and asbestos cement pipe
  8. Pipes and tubes of other materials and they are normally designated by the material used for manufacture such as rubber, ceramic, lead, fiber glass, titanium and Inconel etc.

Pipes and tubes are also designated by the method of manufacture such as

  1. ERW pipe, HFI welded and electric fusion welded pipe
  2. SAW pipe: LSAW and DSAW pipe
  3. Spiral welded pipe and SSAW pipe
  4. Pipe produced by UOE process
  5. Seamless pipe: the various processes for seamless pipe manufacture are Pierce and Pilger rolling process, Plug rolling process, Continuous mandrel rolling process, Push bench process, Pierce and draw process, Tube extrusion process, Cross rolling process, Assel rolling process and Diecher process. The rolling mills are normally multi stand continuous mills.
  6. Cold drawn pipes
  7. Cast pipe and centrifugally cast spun pipe
  8. Fabricated pipe

Pipes are often designated by the media they are conveying such as water pipe, steam pipe, air pipe, oil pipe, gas pipe, slurry, sewer pipe and exhaust pipe etc.

Pipes are also sometimes designated by the property of the media being carried such as gravity pipe, low pressure pipe, high pressure pipe and heat pipe etc.

Pipes are sometimes designated by the type of finish such as plain pipe or corrugated pipe.

Pipes are also differentiated by the method of their joining which can be welding, threading, mechanical coupling, flanged joining, soldering, brazing, compression fitting, push on gasket fitting, flaring and crimping.

Pipes are also identified by the type of lining used for corrosion and heat protection such as refractory lined, insulation lined, Cement mortar lined, epoxy coated, rubber lined, Bitumen mastic lined, Poly Urethane lined, and PE lined pipe etc.

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