PSV/PRV Outlet Configration

GA Simon

I rated u Simonsd

I think this query would be much better in instrumentation forum.

With respect that is utter balderdash.

The specific issue the other guest has is with regard to layout and piping arrangement and so this is best addressed by a piper and / or Process engineer which is my background.

Relief valves are an oddity in terms of classification - are they the responsibility of mechanical, process or instruments - I have seen them classified under all of those groups individually in some workplaces and between a combination of two in others. Consequently the general area is the BEST place for this query.

In my experience the instrument group are limited to actually buying PSV's - the clever bit of developing the sizing cases, calculating required orifice etc is carried out by the Process group.

"Can we use concentric reducers in discharge of PSV (For Gases)?"

This appears to be a general (or rhetorical) question. It would have been nice if the poster had given us a sketch or a very good verbal description of the Outlet configuration.

The general answer to your question is "Yes" you can use a concentric reducer in the outlet of a PSV (Pressure Relief Valve). You can also use an Eccentric reducer in the outlet of the same PSV. In fact it is recommended. There is always the proverbial "Yes but" (exception) to any rule.

In this case it has to do with which direction you are changing pipe size. You should not ever reduce the size of a PSV discharge line. The line should as a minimum stay the same size or even better increase in size. This increase in size should be as close to the PSV as possible. Yes you are using a piping fitting called a "Reducer" but you are using it to increase the line size thus reducing the back pressure on the PSV.