What is Backpressure testing of PRV?

PRV Backpressure Testing;

Speaking of PRV testing, everyone knows (1) Pop Test or Set Pressure Test. It is a test whether PRV can open at Inlet Pressure as set and or (2) Seat Tightness Test, which we call Leak Test, which is the test of leakage between Disc and Seat of PRV after Pop Test.

But for Closed Bonnet PRV in a closed system and does not require Fluid is leaking to the outside (Discharge to Closed Systemmust be made Backpressure Test on Requirement of ASME BPVC Section VIII, Div.1
What is backpressure test of PRV.png
The Backpressure Test is a compressed air or gas at a pressure of at least 2 bars. Go from the outlet side of the PRV to see if the Body, Bonet, Bellow, including Gasketed Joint and Connection are leak or not. Which we will use soapy water to help find the leak.
What is backpressure test of PRV 2.png
To do Backpressure Test can also detect leaks of Bellow’s principle is that if a leakthrough  Bellow we can Detect the hole Vent ‘s Bonnet.

What if we do not carry out Backpressure Test?

The leak of Bellow would make it unable to compensate Backpressure as the result PRV can not open the vent pressure to meet Set Pressure pre-set and leakage of Fluid on the outside could harm the environment or device.

What is Backpressure of valve

Additional example of typical damages on Bellow type PRV and how important of Backpressure testing.

Chloride Cracking on Austenitic Stainless Steel Bonnet and Corrosion Pits on Bellow ;
The picture is a case of the example of Bonnet and Bellow who found leaks during the Backpressure Test.
Bellow backpressure test leak.png
Stainless Steel Bonnet causes stress corrosion cracking which causes chloride content and water in Common Outlet Pipping.
Also, the Stainless Steel Bellow found a Corrosion Pits because Chloride Content and water in the Outlet’s Pipping’s as well.
Bellow backpressure test leak 2.png
Anyway, don’t forget to do the Backpressure Test.

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