3 replies to this topic

[Engineer87]

Hello Guys,

My client design a skid in which they discharge PSV into another pipe that already installed with two PSV.  I dont think its a good

 

engineering practice to vent relief pressure into the piping system. What you guys think?

 

 

Summary: 

 

"PSV-1002 is meant to release vapour fluid when the system between ESDV-1000 and P-1000 is blocked and thermal expansion (or fire) occurs and the expansion bottle is empty and hence the PSV will release into an empty "vessel". Since thermal expansion is a low volume release the expansion bottle (if empty) is sufficient to contain the release and avoid release into the environment. In the event of a fire, and the expansion bottle full, PSV-1002 will release into a full fluid and hence cause PSV-1000 and 1001 to release.

 

 

According to API 521 it is not recommended to have restrictions downstream of a PSV and it is not allowed to have a PSV release into another PSV.Please confirm??

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Edited by Art Montemayor, 21 March 2018 - 06:29 PM.
Removed distracting highlighting

[Bobby Strain]

Your company should have sent this client elsewhere. No telling what other dangers lurk.

 

Bobby

[Technical Bard]

This is very bad practice.  First of all, what is the backpressure on the first valve?  COnsidering the downstream PSV is set at a HIGHER pressure it is entirely possible the first one will NEVER lift, and the upstream system is NOT protected.

[query]

It should be routed to vent separately or connected to the outlet of other PSV. 

connection to the inlet of PSV is not correct.