SteamPedia

The Complete Steam Guide


What MOC should I select for Steam Pipelines?

The selection of steam piping material depends primarily on the temperature of steam being used.

Carbon steel can sustain temperatures below 427°C. Above this temperature, graphitization of carbon steel occurs thus, rendering it brittle. So, Alloy steel is used as the steam piping material for temperatures above 427°C as it has better material properties at elevated temperatures.

Carbon steel pipes are suitable for steam at a temperature below 427°C. The piping standard used for saturated steam according to IBR is: A106 Grade B Seamless Schedule 40. The schedule of the pipe may change with the pipeline thickness calculations as per IBR.

For superheated steam applications above 427 deg C selection of material depends on Pressure – Temp conditions of the specific application. Some of the piping standards are :

ASTM A 335 Grade P11 or Grade P12 or Grade P22

Upgraded materials are picked up with higher Pressure – Temp conditions.

ASME Sec II has provided material standards for pipes used for process and power applications.

ASME B 31.1 gives guidelines for piping specifications for power piping while ASME B 31.3 gives guidelines for piping specifications for process piping.

These codes give guidelines for constructing the piping and include the following :

  • Thickness calculation of the pipe.
  • Material of pipe to be used.
  • Fabrication of the pipe.
  • Inspection of welding defects.
  • Testing of pipes.