Safety Valve Servicing/Testing Facilities

[Sharik]

There are PSV Test Stands being sold now which have a high pressure compressor feeding 1/2" tubing to the inlet of the PSV. These are being sold as certified for testing all sizes of PSV, via an adjustible clamp/flange assembly.

This is quite different than what I'm used to. I've always used a Test Bench with a large receiver so that there was enough volume to actually pop open all the PSV's up to the maximum set pressures and PSV inlet sizes as authorized in the organization's PSV QC Program.

Are these PSV Test Stands with pressure but without volume, acceptable for testing 'UV' stamped PSV's? Is it acceptable to just simmer a PSV when testing or is it mandatory to pop the PSV 100% open?

 

[don1980]

For gas service PSVs, one performs a pop test. Capacity testing isn't necessary - it's not part of the routine PM for PSVs. Full capacity isn't reached until the overpressure reaches 10%, and, except for small PSVs, test stands are not capable of achieving that. A test stand should be capable of popping the valve. I can't say for sure, but the stand you mentioned is probably capable of doing that.

 

[Sharik]

I know we are not doing PSV capacity tests but aren't we supposed to test the full action of the safety valve? Doesn't that mean popping 100% open and then closing. I also know we can't check the blowdown. Isn't this especially crucial as API allows if a PSV passes the prepop test, it doesn't need to be dismantled, serviced, etc.?

These little test stands do not have enough volume to pop open a PSV larger than 1" NPS. They just barely simmer the PSV. By just simmering the PSV, how would we know if there isn't an issue with the stem which could bind in guide, or the correct action of the sprint, etc.?

I am more used to organizations having facilities complying with API 576,with reservoir at least 12" (30cm) diameter, 6' (180cm) in length and with at least one test connection of 4" NPS.