PSV Open To Atmosphere Forces

Hello Stressers,

For an open to atmosphere PSV System, do we need to model a PSV force at the outlet/edge of discharge piping. If yes, what is the basis for this force?

Thanks all for your opinion in advance.

Cheers!!!!

see ASME B31.1 Nonmandatory Appendix II and API 520 Part II Par 5.8.

Thanks Faizal for that info. How about if the system has approximately 6m horizontal run on the discharge pipe. Is it the same formula given in the Code?...

Thanks!!!

6m Horizontal?
I guess both codes do not give you specific formula to solve.
It's more like closed discharge... can you give us the scheme? or condition?

Hello... I don't have the drawing with me at the moment but basically, after the PSV there's a reducer (outlet size is bigger), then an elbow going up then after going up it turns horizontal straight (open at end)...Maybe the PSV location is far from safe discharge point. Not sure what's the real reason behind..

Anyway, is specialize calculation required which relates to fluid flow and back pressure...

Borzki,

You can find my opinion on this subject in

http://65.57.255.42/ubbthreads/ubbthreads.php?ubb=showflat&Number=21003
http://65.57.255.42/ubbthreads/ubbthreads.php?ubb=showflat&Number=33633

Maybe my posts would help you a little.

Best regards.

Thanks mariog for that bountiful information. Need to do a lot of reading and studies in this case. Maybe the client is aware of this issue so he commented on it. From safety standpoint, what I can say is to restrain the system sufficiently as a countermeasure against unexpected forces and maybe vibration.

Cheers!!!!