In fact API 527 (3rd edition, reaffirmed 07/2007) states "90% of set pressure". I agree with Duwe that 90% of CDTP should be used instead. It seems to me API is not always precise with the use of it's own definitions.
CU, Smiler
Hi all,
I'm comparing different sources on various subjects of safety relief valves and found different diagrams showing a "typical" valve opening/closing characteristic.
Of course there is API520 (8th ed.) which provides figure 6 (page 14), the Consolidated Catalogue for Safety Relief Valves...
Hi all,
Yes, I know that the whole API always states that gauge set pressure should be used to check if built-up BP is within allowed limits. Still this question arises frequently and is answered differently. Most engineers I ask intuitively vote for CDTP as reference, me too. I searched the...
Hello Latexman,
thanks for your comment, I agree on the basic steady-state force balance, but I think we have to consider the system dynamics. Assume the valve is really designed to open at 5 barg vs. atmospheric and reach the desired relief rate at the code allowed limit of 11 barg inlet (120%...
I would like to pick up don's answer regarding overpressure limitation (or lack there of). As don already pointed out, the MAWP in the above example would allow relieve pressure of 11 barg (process scenario). With a set pressure of 5 barg it would mean allowable overpressure of 120%...
