Critical Piping System Used at Thermal Power Projects - Why?

Piping systems are crucial when it comes to construction work and infrastructural projects. Having quality and reliable piping done will result in a sturdy and safe project. Therefore, it is important to understand the differences in piping systems and how different projects require different piping.

Thermal Power Projects

Thermal Power projects constitutes major chunk of power producing resources all over the world and is dominating the power industry for over a century.

For any power plant, piping is like arteries in a human body, which transports the main service fluids at very high temperature and pressure.

What is the Critical Piping System?

Water is the main process fluid in any thermal power plant, which is subjected to very high pressures to absorb more enthalpy (heat units) per unit mass of fluid. Also when the medium is heated to a very high temperature, it becomes high pressure and high temperature steam. Such a medium is to be transported from one equipment to other equipment within a power plant for converting the thermal energy into electrical energy. Those piping systems which does the transport of high pressure and high temperature water and steam in a power cycle is called ass Critical Piping systems.

Following systems are considered as part of Critical Piping Systems.

  • Main steam – Steam from Boiler outlet to HP Turbine inlet
  • Cold reheat – Return Steam piping from HP Turbine outlet to Boiler reheater
  • Hot reheat – Steam from Boiler Reheater outlet to IP Turbine inlet
  • HP/LP bypass piping – Steam Bypass piping for HP and LP turbines
  • Boiler feed water discharge Piping from Feed Pumps to Boiler Economiser Inlet

Critical Piping Fabrication:

Since these piping systems handle High Pressure fluids (Water / Steam), they are of very high thicknesses. Also as the medium temperature is very high, usage of high alloy steel is envisaged, depending upon the temperature levels.

Making a flexible layout and designing appropriate support system is utmost important, considering the very high expansion levels experienced during operation.

Piping design and fabrication is done as per ASME B 31.1 for Thermal Power plants.

Since these systems require usage of materials like SA335P92, SA335P91 and Carbon steels like SA106GrC, fabrication including welding need to be done with more stringent process parameters to have proper weld quality.

Also, to reduce pressure drop, in turn saving energy, most of these systems require Pipe bends instead of regular elbows. Bending of high alloy steel piping of large diameter and higher thicknesses is a very big challenge in a manufacturing process.

Codes and standards like ASME, IBR provide stringent procedures to be adopted while these systems are fabricated.

DEE Piping has a greater experience in fabricating Critical Piping systems up to 800 MW capacity for many of the power plants in India and has suppled critical piping to various EPC companies during the last decade and successful power generation from such units is a running certificate to DEE’s credentials.