Relief Temperature above Design Temperature?
Relief Temperature above Design Temperature?
(OP)
I am trying to size relief valves for a pressure vessel that is rated for 250 psig @ 115 F it was originally designed to store liquid Propane. The vessel is made of carbon steel (SA616 for the shell and SA516 for the heads). The vapor pressure of the contents, in this case Tetrahydrofuran is only about 6 psia at 115 F. This causes the relief valves to be extremely large. I am wondering if there are any guidelines (API, etc) about relief temperature. Is it allowed to exceed the vessels rated temperature so that the relief valves could be set at a higher pressure? (The only relief case for this storage tank is the fire case.)"





RE: Relief Temperature above Design Temperature?
Good luck,
Latexman
RE: Relief Temperature above Design Temperature?
I could not find any reference that mentioned the MAWT and relief temperature and this low MAWT was giving me problems.
Thanks
StoneCold
RE: Relief Temperature above Design Temperature?
Good luck,
Latexman
RE: Relief Temperature above Design Temperature?
I have come accross this issue many times and it is true that sometimes the relieving temperature is higher than even the design temperature of the relief valve itself... any explanations? Still do not understand.
Thanks.
RE: Relief Temperature above Design Temperature?
Good luck,
Latexman
RE: Relief Temperature above Design Temperature?
As far as I understand it the API520 fire case is a scenario where deluge fails and the question is now to prevent further escalation. The vessel (and equipmennt) are assumed lost anyway. Off course the temp must not be so high that the vessel bursts but a temperature higher than the design temperature is acceptable.
Best regards
Morten
RE: Relief Temperature above Design Temperature?