I am analysising a system where the working pressure is some 92% of the flange rating at op temperature, and the system has some high moments acting on some of the flanges.
Using the Kellogg formula for Pe + Pd < Pa, is clear enough, but my question is what is Pa. I read it as Pa is the flange rating at pressure, with my moments and forces [Pe] coming from the OPE load cases rather than SUS and EXP or OCC. If this is the case I need only when the system drops to some 70% of operating pressure have I got any leeway.
I have seen a report from a well respected analyst who, with out stating it seems to be using 1.33 * Pa or more [surely not the displacment stress range v allowable stress ratio?]
Can anybody shed some light on this or set me right