Relief Valve outlet Pipe size
Relief Valve outlet Pipe size
(OP)
Hey Everybody:
Does ASME Code require that the outlet of a conventional spring operated relief valve be larger than the inlet? I have seen a few NB marked valves that are 3/4" x 3/4", but the ones I am looking at our 3/4" x 1". My client currently has a coupling reducer on the outlet, turning it into a 3/4" x 3/4". I assume if we show that minimal back pressure occurs (less than the 10% overage rule of thumb) it would be ok to do this.
Does ASME Code require that the outlet of a conventional spring operated relief valve be larger than the inlet? I have seen a few NB marked valves that are 3/4" x 3/4", but the ones I am looking at our 3/4" x 1". My client currently has a coupling reducer on the outlet, turning it into a 3/4" x 3/4". I assume if we show that minimal back pressure occurs (less than the 10% overage rule of thumb) it would be ok to do this.





RE: Relief Valve outlet Pipe size
casflo
RE: Relief Valve outlet Pipe size
The only size restriction I am aware of for Section VIII, Division 1 vessels ("U" stamped ones), minimum size of inlet of PRV should be not less than 1/2" NPS. Outlet sizes is defined by flow capacity of PRV and could be either the same size or one size bigger.
Regards,
Kurt