PSV flow rate 1

[waleedarafah]

Dear all
Could you help me to with any standard , specification to how calculate the flow rate needed for sizing orifice area for pressure safety valves installed on pig trap & pipeline for oil & gas services

 

[EmmanuelTop]

Start with API 521. I believe you can find some earlier revisions on the internet.
Plenty of manufacturers publish PSV sizing manuals. See some of these:

http://valves.pentair.com/valves/Images/PVCMC-0296-US_tcm106-35825.pdf

http://www.isibang.ac.in/~library/onlinerz/resources/enghandbook3.pdf

http://www.spenceengineering.com/pdf/Spence-SRVs.pdf

Dejan IVANOVIC
Process Engineer, MSChE

 

[waleedarafah]

Thanks Dejan,
I found API 521, after reviewing i understand we use PRV for P/L in two case thermal relief & fire case scenarios.Please advise
but i can not find the equation for flow rate calculation in fire case.

Could you tell me what is the cases for using PSV in Gas pipeline, and how to calculate the flow rate

 

[TD2K]

Look at API 520 also. Typically, though it depends on your configuration, the PSV is located on a high point so in a fire, you are only relieving vapor in a fire case. The fire load is the heat input / latent heat. You can also do the calculation just as thermal expansion which will give you a smaller area but that is unrealistic in my opinion as it ignores the overpressure case once the flluid starts to boil.

Launchers/receivers are typically not left full of liquid so I'm not personally sure just how realistic a fire case would be. no liquids, no vaporization during a fire. That's your call of course depending on your company's operating and design practices.

 

[LuNL]

there is also a manual book about selection and sizing from LESER PSV, partly secured, but most is open to view.
it is also very helpful, just google "LESER engineering handbook"