Need help Determining PRV Set pressure

[POL23]

I'm replacing 2 PRV's(3/4" by 1 1/2" Stainless Steel) on Jet A-1 fuel storage tank inlet 8" and outlet 5" pipeline. MAWP based on the highest operating pressure reasonably expected to be encountered is 96 PSIG (Pump deadhead pressure 87 PSIG plus 10%)

Questions:

- At what pressure setting should the PRV's be set to open

- What factors must be use to determine PRV set pressure

- What Code/standard governs PRV pressure setting

Any help would be greatly appreciated!!

 

[EGT01]

The first thing you need to do is determine the code to which the tank was constructed. Generally, the code used to fabricate the vessel will also provide guidance for overpressure protection of the vessel.

Based on your description of relief valves and pressure rating of the tank, you are dealing with a pressure vessel that may have been constructed to ASME Section VIII, Division 1 but this is the type information you need to verify.

ASME Section VIII does provide guidance for overpressure protection and further guidance can be found in API Recommended Practices RP520 Part 1, RP520 Part 2 and RP521.

Though the following are good online resources, they should not be substitutions for the above documents.

The Spirax Sarco link has a complete learning module on relief valves, this one in particular discusses considerations for determining the relief valve set pressure...

http://www.spiraxsarco.com/learn/modules/9_3_01.asp

The type of relief device can also be a factor in determining the set pressure.

Another good reference is the Crosby Pressure Relief Valve Engineering Handbook.

http:////

http://www.tycovalves-na.com/ld/CROMC-0296-US.pdf

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[EGT01]

Looks like I got carried away with the slashes in the link to the Crosby Handbook. Here's the correct link...

http://www.tycovalves-na.com/ld/CROMC-0296-US.pdf

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