1 reply to this topic

[arkae]

hi every one...

 

A safety valve is provided downstream of a pressure reducing control valve in natural gas system that supplies gas to gas turbine.

 

This safety valve has been designed for full flow in case of failure of pressure control valve, to relive the pressure.

 

What should be the overpressure that we need to provide to the vendor?

 

As per ASME secVIII DivI, overpressure shall be 10% for boiler external piping and 20% for fire case.

As explained above, the relief valve is designed for failure case of pressure reducing valve, so I have to provide 10%.

 

But Should I provide over pressure of 10% or 20% ?

 

What would happen if I provide overpressure of 10% and incase fire occurs.

 

What is the actual practice in this scenario?

 

 

Thanks in advance

[fallah]

arkae,

 

The PSV should be sized based on governing scenario either upstream PV failure to be wide open or fire case...then at first you should specify the credible scenarios for mentioned PSV...