[Anonymous]

Dear All,
Can anybody tell me about how to design the safety valve installation vent pipe,discharge elbow and valve.

[shahrulizwan abdul hamid]

Hi Jop,

Just ran through some old topics in the forum about PSV / PRV / TRV and came about to this discussion.
I have one question on the outlet piping design of the PSV that going to closed system.
I believe the optimum design will be the block valve connect straight to the PSV outlet, but in some cases where there is a constraint in space, is it allowed to have a spool in between the PSV outlet and the block valve? This means the valve will be in vertical position after the spool and elbow going down.
Is there any concern on design like this. I have seen one or two times design like this.
Appreciate if you can elaborate on this.
Thanks Jop

regards,
Ajak Piper

[James Pennock]

Ajak,
It seems I did a bad job of explaining my recommendation. I will try again.
You wrote: “I believe the optimum design will be the block valve connect straight to the PSV outlet, but in some cases where there is a constraint in space, is it allowed to have a spool in between the PSV outlet and the block valve?”
– Yes, a spool piece is allowed between the PSV outlet and the Block Valve.

“This means the valve will be in vertical position after the spool and elbow going down.”
– Not necessarily. We need to consider the orientation of the two items: Item #1, the discharge pipe and item #2, the discharge block valve.
– Item #1: (a) The Discharge pipe can exit the PSV and proceed to the Flare Header in one single horizontal run. Or (b) the Discharge pipe can exit the PSV and turn down for some vertical distance then turn horizontal and proceed to the Flare Header.
– With Item #1 (a) the Gate Valve would be positioned in a horizontal pipe run but the Item #2 (Valve) needs to be rotated down so the Valve Stem is in the horizontal.
– With Item #1 (b) the Gate Valve could be placed in either of the two horizontal portions. If the valve is placed in one of the Horizontal runs than the previous positioning advice applies. if the Gate Valve is located in the Vertical pipe run than the Valve stem will automatically be in the horizontal configuration, no other action is required.

[Author]

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