Components Used in Piping Systems

A Piping System is an assembly of various components put together with a proper method

of joints, functionally to transport fluid from its source to destination. The different

components put together are defined as piping components.

They are designed for withstanding the operating and design conditions specified in the

process parameters. Each component used in piping systems are specified in piping

specification.

Pipe system components used are

1. Pipe

2. Pipe fittings

3. Flanges

4. Gaskets

5. Bolting

6. Valves

7. SpecialitiesPipe:

Pipe is a tubular product used to convey a fluid. The pipe sizes are generally identified

as nominal bore (NB) or nominal pipe size (NPS). Pipes have fixed outside diameter (O/D)

and variable inside diameter based on the thickness selected.

The codes used for pipe selection are

ASME B 36.10- Welded and seamless wrought steel pipes

ASME B 36.9- Stainless steel pipes

The different sizes and thickness which are available are specified in above standards.

Thickness of pipe is generally designated by schedule no. and the corresponding thickness

specified.Types of pipes:

1. Seamless:

Pipe produced by piercing a billet followed by rolling or drawing or both.

They are used for high pressure applications.

2. Welded:

a. Electric fusion welded (EFW): Pipes carrying a single or double longitudinal but weld

joined wherein coalescence is produced by manual or automatic electric arc welding in the

preformed tube.

b. Electric resistance welded: (ERW): Pipe carrying ongitudinal but weld joined wherein

coalescence is produced by heat obtained from resistance of the pipe to flow of electric

current in a circuit of which the pipe is a part and by application of pressure.

3. Forged and bored:

Pipes prepared by forging and then boring to the desired thickness.Various methods of pipe joints:

1. Butt weld pipe joints

2. Socket weld pipe joints

3. Screwed pipe joints

4. Flanged pipe joints

5. Spigot socket pipe joints

Generally used pipe materials areCarbon steel:

ASTM A53- welded and seamless pipe, black and galvanised.

ASTM A106- Seamless cs pipe for high temperature services.

ASTM A672- Electric fusion welded steel pipe for high pressure service at moderate

temperature services.

Stainless steel:

ASTM A312- Seamless and welded steel pipe for low temperature services.

A409-welded large diameter austenitic steel pipe for corrosive and high temperature

services.

ASTM A358- Electric fusion welded austenitic chrome -nickel steel pipe for high

temperature services.

Low alloy steel:

ASTM A335- Seamless ferritic alloy steel pipe for high temperature services.

ASTM A691- Carbon and alloy steel pipe, electric fusion welded for high pressure service at

high temperature.

Low temperature carbon steel:

ASTM A333- Seamless and welded steel pipe for low temperature services.

ASTM A671- Electric fusion welded steel pipe for atmpospheric and low temperature

services(sizes >=16in NB)

Types of Pipe FittingsThe components used in piping system post details about the various components. These are used changing a direction, joining different sizes of pipes, taking a branch-off, etc. are generally referred to as Pipe Fittings.

Different Dimensional Standards available for pipe fittings

ASME B 16.1-Cast Iron Pipe Flanges and Flanged Fittings

ASME B 16.3-Malleable-Iron Threaded fittings

ASME B 16.4-Grey Iron Threaded fittings

ASME B 16.5-Pipe Flanges and Flanged fittings

ASME B 16.9-Factory-Made Wrought steel Butt welding

ASME B 16.11-Forged Fitting, Socket welding and Threaded

ASME B 16.28-Wrought Steel Butt welding Short Radius Elbows and Returns

ASME B 16.42-Ductile Iron Pipe Flanges and Flanged Fittings

ASME B 16.49-Buttwelding Induction Bends for Transportation and Distribution System

BS 1640-Buttweld Fittings

BS 3799-Socket weld and Screwed end fittings

Pipe fittings classification based on the end connections1.Socket weld/ Screwed end fittings:

Dimensional standard-AME B 16.11/BS 3799 Sizes –upto  4” NPS only.

These fittings are designated by pressure class which represents the maximum cold non-

shock working pressure and the thickness corresponding to that class.

The pressure classes used to designate these fitting are:

2000 # Class: Applicable for Screwed fittings only, Thickness-SCH 80 or XS

3000 # Class: Socket weld fittings, Thickness-SCH 80 or XS & Screwed fittings, Thickness-

SCH 160

6000 # Class: Socket weld fittings, Thickness-SCH 160 & Screwed fittings, Thickness-SCH

XXS

9000 # Class: Applicable for Socket weld fittings only, Thickness-SCH X XS

The screwed ends for fitting are generally with Taper threads. These threads can be

Nominal Pipe threads (NPT) or British Screwed Pipe Threads (BSPT).

The socket weld/screwed fittings are generally forged.

The different grades of material used for these fittings are:

ASTM A105-Forged Carbon Steel

ASTM A181-Forged Carbon Steel for General purposes

ASTM A182-Forged Alloy Steel and Stainless Steel

ASTM A234-Wrought Carbon Steel and Alloy Steel pipe fittings for moderate and elevated

temperatures

ASTM A350-Forged Alloy Steel for Low temperature Services2. Butt weld end fittings:

Dimensional standard-AME B 16.9/ AME B 16.28/BS 1640

These are fittings are with Butt welded ends.

They are available in both seamless and welded type. They are usually with the same

thickness as pipe.

The different grades of material used for these fittings are:

ASTM A234- Carbon Steel Fittings for Moderate & High temperature Services.

ASTM A403- Austenitic Stainless Steel Pipe Fittings.

ASTM A420- Carbon Steel & Alloy Steel Pipe Fittings for Low temperature Services.

3. Flanged end fittings:

Dimensional standard-AME B 16.5/BS 1650

These kind of fitting have both ends Flanged and are used in places where welding is not

allowed.

They are cast fittings.

The different grades of material used for these fittings are:

ASTM A216- Carbon Steel Casting.

ASTM A403- Stainless Steel Casting.

ASTM A420- Alloy Steel Casting.