PSV Assembly
PSV Assembly
(OP)
Is bleeder required between the isolation valve and PSV at the discharge side?
As per API, it shows a typical assembly of PSV with a bleeder at the discharge side, but here on my current project(existing plant) they don't installed bleeder at the discharge.
As per API, it shows a typical assembly of PSV with a bleeder at the discharge side, but here on my current project(existing plant) they don't installed bleeder at the discharge.





RE: PSV Assembly
I suppose it would largely depend on the fluid.
If you're shutting down just one unit in a facility and don't trust the seal on the PSV's downstream block valve, you might want to check it by carefully cracking open the bleed valve for backpressure after closing the downstream block valve.
Bigger brains than mine hang around here, so you'll likely get more thoughts. Good question.
Paul
Piping Design Central
RE: PSV Assembly
It was a closed type relieving system which was most probably the commodity inside is toxic.
My conviction is the reason for the bleeder on the discharge side is to release the build-up pressure between the psv and the isolation valve in case you shut off the valve and want to remove the psv. I'm just wandering about the setup in the existing plant which doesnt have a bleeder, on how they release the build up pressure. Do they crack the pressure on the flange connection?is that safe?
RE: PSV Assembly
If you've got a liquid, you could have issues with thermal expansion causing excess pressure.
Cracking flanges to vent / drain pipework is not safe, but has been used in many instances in the past to do just that.
Hence I think you do need a bleed valve between the two, but you do need to think about the volume and would be an issue when coming up with a method statement and risk assessment to remove the psv.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: PSV Assembly
Piping Design Central
RE: PSV Assembly
Kind of a bit addictive at the moment., I'm sure it will pass....
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: PSV Assembly
Good luck,
Latexman
Need help writing a question or understanding a reply? forum1529: Translation Assistance for Engineers
RE: PSV Assembly
Unfortunately, the current design instruction in our project is to make our design same
as the existing(like to like).Hopefully this will be changed.
RE: PSV Assembly
A good spot though.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way