Paralleling multiple safety relief devices for a pressure vessel
Paralleling multiple safety relief devices for a pressure vessel
(OP)
When (a) a relief valve is paralleled with a rupture disk / another relief valve is it acceptable to use the same pressure vessel vessel nozzle with a branch in the piping (with piping size suitably selected, of course) or is it necessary to use separate vessel nozzles to attach each relief device?





RE: Paralleling multiple safety relief devices for a pressure vessel
Good luck,
Latexman
To a ChE, the glass is always full - 1/2 air and 1/2 water.
RE: Paralleling multiple safety relief devices for a pressure vessel
Yes, I did mean 2x100% capacity redundancy.
But out of curiosity, would your recommendation be any different had the paralleling been for other reasons. e.g. Multiple relief scenarios, or split capacity etc.
RE: Paralleling multiple safety relief devices for a pressure vessel
It is permissible to have a single nozzle serving two relief valves, or even have them on the process piping. Check API RP 520 part II- Installation of pressure relieving devices; which includes typical layouts. The key design parameter is the allowable pressure drop in the inlet piping. For a conventional relief valve, the inlet losses must be no more than 3% at full flow to avoid "chattering" of the relief valve.
best wishes,
SShep