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PSV relief case

PSV relief case

PSV relief case


I'm currently doing PSV failure consequence assessment on an oil platform and I have a question on a PSV downstream of an accumulator (refer to attached sketch). I have found few cases like this but I am not sure what is the relief scenario for the PSV. What is the PSV for?

Thank you.

RE: PSV relief case

That's not much to go on, so I'm guessing.

Closed valve and overpressure from PD pump?
Closed valve and thermal expansion?
Fire exposure on vessel?

Good luck,

Technically, the glass is always full - 1/2 air and 1/2 water.

RE: PSV relief case

It looks like a part of the Hydraulic Power Unit loop, but as Latex says it is impossible to figure out the relief scenario based on the sketch only. What is written on the P&ID, next to the PSV symbol?

Process Engineer, MSChE

RE: PSV relief case

It is still unclear. Can you dig into PSV Sizing Report or HAZOP, and identify the function and the scenario for this PSV?

Process Engineer, MSChE

RE: PSV relief case

This is probably a firecase PSV dedicated to the accumulator / bladder - the designer believes the bladder is to be treated as a pressure vessel.

If you want a firecase PSV to operate only for firecase, then its setpoint should be some what higher than than the blocked discharge PSV.

Depending on which country this HPU is located in, you may have this firecase PSV setpoint set at 1.05x 228barg, or 1.1x 228barg. So this setpoint needs to be corrected. Also check the local codes for max permissible relieving pressure used in the calculation for deriving the firecase load.

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