Check valve downstream of a PSV 1

[maddocks]

In a recent HAZOP, operators told me that they were under the impression that we could not install a check valve on a PSV discharge. Can anybody point me to the code that would reference this?

 

[Ashereng]

I don't know if it is code.

I do know I have never done it, or seen it done.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[JLSeagull]

API RP 520 paragraph 9.3 may address the issue. Some of the installation guidelines related to back pressure address the issue but without mentioning a check valve per se.

 

[JimCasey]

A PSV >IS< a check valve...spring-loaded closed. Aside from the code issues that JLSeagull mentioned, it's just unnecessary. Anything that comes backward in the line should go to a drain.

 

[proinwv2]

Nothing should backflow thru a PSV; it is a check valve.

Besides, I can not think why you might want to place any restrictive device, or a device subject to mechanical failure downstream.

Paul Ostand

http://www.ostand.com

 

[zdas04]

I guess a rain-cap is a kind of check valvish sort of thing and I've put them on some locally-relieving valves. Other than that I'm with everyone else.

David

 

[unclesyd]

Had lunch with an old AI buddy an posed your question and before I could finish his answer was "No! Hell No, No way".