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Psv Piping Layout

psv flare relief

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#1 erwinfs


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Posted 16 April 2018 - 09:43 PM

I currently designing a gas receiving facility that have all reliefing gas directed to an existing flare header.


The existing flare header has 8 meters elevation. If I want all the inlet line and outlet line of the PSVs have no pocket, I should locate my PSVs at higher than 8 meters elevation and therefore this would be costly for the pipe support.


My question is, is it absolutely impermissible to have any pocket in my PSV line (both inlet & outlet)? Or is there any special case that permit the PSV lines to have pocket?

#2 Technical Bard

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Posted 16 April 2018 - 10:16 PM

Ideally, the PSV should be located above the flare header, otherwise condensation in the flare header could fill the discharge of the PSV with liquid.   I have seen designs where the PSVs were located below the flare header, but it becomes necessary to consider a method to ensure there is no liquid in the discharge.  Some owners will allow this to be by procedure (operators drain is every shift), or using a trap-like device.  But it is definitely not recommended.

#3 fallah


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Posted 17 April 2018 - 02:18 AM



Where the PSV outlet line must be lower than the flare header, as in your case, a drain pot equipped with a manual valve shall be installed along the outlet line preferably at low point. This manual drain valve shall be accessible from the grade or a platform. Obviously, the pot shall be drained by relevant operator regularly. In the case the pot is subject to subzero ambient temperature, it should be equipped with heat tracing to avoid blockage due to freezing.

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