check valve on Rupture disk outlet

[Rajjil]

There is a need of providing the flow switch at outlet of Rupture disk installation for liquid relief application to tank. 65 psig back pressure is created because of flow of liquid in another pipe where the RD will be discharging, which is 2000 ft long line going to tank.
Instrument asked me to provide a check valve at outlet so that when there is flow in otherline where RD outlet is connected the flow switch does not sense the flow.
My question is "can I provide a check valve at Rupture disk outlet?"

 

[zdas04]

You already have such a mess that you can pretty much do anything you want. I'm going to assume that you've done all the pressure drop calculations and with 2,000 ft of pipe you still have adequate flow, that you have taken into account the possibility of phase change and possible cavitation, that if the second stream is variable your rupture disk will still handle the capacity required.

With all that, a check valve will add a psi or so of extra backpressure as long as it doesn't scale up and seal itself closed. I wouldn't put a check valve in a safety device discharge, but then I also wouldn't dump it into a process line or run it 2,000 ft.

Flare headers are used all the time and are occasionally longer than your 2,000 ft, but I've never heard of comingling safety-device exhaust with a normal process, but maybe that is just that I've never heard of it.

David

 

[Chance17]

I would say no.
Any restriction in a pressure relief path should not be installed.
Orifice plates, in-line flow meters (switches), check valves are at the top of my list of restrictions.
You can detect rupture disk activation by other means.

 

[Latexman]

Like a BDI - burst disk indicator. Google it.

Good luck,
Latexman

 

[Latexman]

What's the set pressure of the application? Do the pressures work out so you can put a RD at the application and another at the outlet such that the 65 psig backpressure will not burst the one at the outlet? Just wondering.

Good luck,
Latexman

 

[StoneCold]

Maybe you should look at a buckling pin system.

Regards
StoneCold

 

[JoeWong88]

Downstream of pressure relief device, devices potentially causing partial or total blockage which further limit the relief flow shall be avoided. Check valve is one of the potential device.

Burst disk indicator (proposed by Latexman) and buckling pin system with positional switch (proposed by StoneCold) are good idea in detecting RD opening. Besides, provision of double RD with pressure transmitter is another way.

If you select flow switch as mean to detect opening of RD, make sure it does not form a device potential causing partial blockage of relief flow path.





JoeWong
Chemical & Process Technology