I am very experienced on ASME Section VIII PSV sizing, but hardly have any experience on ASME Section I PSVs.
One of our plants has two 150 HP boilers with MAWPs of 150 psig. Each boiler has > 500 sq. ft. of heating area, so I know each boiler requires two PSVs.
After reading through ASME Section I, both PSVs will have set pressure of 150 psig with 3% overpressure. Both PSVs are existing and conventional. They are all Kunkle model numbers 6021-GF01-AM.
The plant wants to pipe the outlet of all 4 PSVs outside of the boiler room/building.
So, given all this, what is the maximum allowable pressure drop on inlet pipe and fittings and outlet pipe and fittings for Section I PSVs?
I know for ASME Section VIII PSVs the maximum allowable pressure drop for conventional PSVs are 3% on inlet and 10% on outlet. With only 3% overpressure for Section I PSVs, those don’t feel right to me. I didn’t see any mention of maximum allowable pressure drop for ASME Section I PSVs in ASME Scetion I, API 520 Parts 1 and 2, or API 521.
Can somebody help me or point me to a resource on this?