Piping:Pipes,Type and descriptions

Piping is an essential part of our life, we are using pipes everywhere for various purposes like water supply, oil field, gas transportation, and used in almost every plant, it is very important and convenient in our productive life.


The piping sector in the world has developed significantly in recent years. Piping has not only improved in terms of availability of preferable quality materials but also improved technologies and processes which make the job role in piping even more attractive. 

A variety of new materials and fittings have replaced traditional materials. Benefits include easy installation, easy-to-use materials, and cost-effectiveness. In this unit, we will study different types of pipes and pipe materials that are widely used by the piping industries today.

Fundamentals of piping

Piping system

A piping system defines the interconnection of whole components connected by a pipe.

Pipes are required to convey the fluids from one place to another in any plant, but only state pipes cannot do this work, for this purpose, fittings, and equipment are also applied like valves, flanges, elbows, reducers, tanks, etc. This whole system is called a piping system.


A pipe is nothing but a hollow cylinder that is used to convey fluids, which can be liquid, gas/air, or a fine-solid particle.

PipesTypes and description

A pipe is nothing but a hollow cylinder that is used to convey fluids, which can be liquid, gas/air, or a fine-solid particle.


Pipes are currently manufactured in a variety of materials depending upon the required properties, these may be made of metal, fiberglass, wood, concrete, or plastic, etc.

Classification of pipes

A pipe may be classified into two main parts :

  • Seam pipe and
  • Seamless pipe

Seam pipe

Seam pipes are actually welded pipes and can be classified into two parts according to the welding processes used,

Pipes welded by submerged arc welding process can also be classified into two types such as:

  • Straight SAW
  • Helical or spiral SAW

Straight saw methods used seam pipes also may be in two types:

  • Single seam
  • Double seam

Seamless pipe

These types of pipes are manufactured and there is no welding on them, that is why they are called seamless pipes.

Pipe ends

Pipes can be identified by their end also such as:

  • Blind end
  • Beveled end
  • Threaded end
  • Special end

                 a-Socket end

                b-Spigot with o ring gaskets

Thus, we see that pipes can be classified according to their weld profile, or ends.

Pipe size

PipesTypes and description

Some international codes and conduct are followed to determine the pipe size, mainly American Standard and British Standard which are as follows: –

Pipe ID

The measurement of the inner surface of any pipe is called ID or inner diameter.

Pipe OD

The measurement of the outer surface of any pipe is called ID or inner diameter.


NPS is a nominal pipe size that comes in inches such that 4” by 2” is the approximate distance between the NPS ID and OD. This is an American system and is measured in inches such as 6 inches 8 inches etc.

Up to 12″, NPS is between ID and OD but above 12 “NPS becomes equal to OD” such as:

NPS 14” = OD of the pipe will be 14”

The OD below 12” pipe is fixed with some standardized code which is given in ASME B36.10, except stainless steel, all types of steel charts mentioned here. Stainless Steel Pipe Thickness Chart Mentioned in ASME B36.19.


DN (Nominal Diameter) between ID and OD is called DN or Nominal Pipe Size (NPS) such as DN 100, DN 200, etc. DN comes from the European system and is measured in mm.

Here point to be noted that NPS = DN is multiplied by 2, Where 1” is equal  to25.4mm but DN is a standard, thus it will be multiplied by 25 only.

Pipe thickness

The distance between ID and the OD is called, the thickness of the pipe, which is usually measured by schedule, but another unit is used to measure the thickness also, which is called gauge.

Detail about gauge and schedule is here

Pipe fittings

Pipe fittings are an essential part of piping. These are used to attach straight pipes to any segment. These can vary in shape and size as per the requirement, some common fittings are as follows:


Elbows are used to turn the pipe at any angle, they are available in a variety of sizes and angles, in addition, they can also be made manually to rotate the pipe at a particular angle. Normally, long radius elbows are used for small pressure drops, whereas short radius elbows are used for high-pressure drops.


To reduce the size of the pipe, a reducer is used, basically, their function is to reduce/control the amount of flow of fluid, it is of two types. Concentric reduce and Eccentric reduce. Usually, Eccentric reducers are used in Pump suction to avoid Cavitation, To maintain elevation (BOP) in the rack, and Concentric reducers are used for Pump discharge, vertical pipeline, etc.


Nipples are used to make close connections in pipes or tubes. These are threaded at both ends.


The work of coupling is also to connect the pipes together, with the help of these couplings, pipes of the same size are connected in a straight line.

weldolet and sockolet

Weldolet and Sockolet originally known as self-reinforced fittings are used for buttweld branch connections where a standard tee is not available due to size, whereas sockets are used for Restrictions and piping of critical/high-pressure service.

Apart from this many fittings are used like Unions, Tees, and Crosses, Bends, Plugs, Caps, Bushings, etc.

Piping standards and relevent codes

. Some of the important relevant institutions and standard piping codes are given below.

  • The American Petroleum Institute (API).
  • The American Iron & Steel Institute (AISI).
  • The American Society for Testing and Materials (ASTM)
  • The American National Standard Institute (AISI).
  • The American welding society (AWS).
  • The American Water Works Association (AWWA).
  • The American Society for Mechanical Engineers (ASME).

Different sections of ASME in piping

  • ASME section I: – Rules for construction of power boiler.
  • ASME Section II: – Materials.
    • Part A – Ferrous materials.
    • Part B – Non-Ferrous materials.
    • Part C – Specification for electrodes & filler wire.
    • Part D – Properties.
  • ASME Section IV: – Rules for construction of Heating Boiler.
  • ASME Section V: – Non- destructive Examination.
  • ASME Section VI: – Recommended rules for care & operation of the heating boiler.
  • ASME Section VII: – Recommended guidelines for the care of power boiler.
  • ASME Section VIII: – Rules for construction of pressure vessels. (Division I & II)
  • ASME Section IX: – Welding & Brazing qualification

Piping materials

Choosing the right type of material is an essential issue in piping. This can be achieved by following standard piping codes such as ASME:

To be continued

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