installing valves for n.g pipelines, before or after hyd. test?

[engahmedbahgat]

Dear friends,

I heard from some engineers, that, conducting hyd. static test on pipeline; must be before installing secion valve rooms,especially for natural gas and crude oil pipelines, to keep valves safely from dust and impurities. is that true or what
thank you in advance.

 

[LittleInch]

There's no such thing as"must" when it comes to these things. If the valves are flanged then I've seen it done, but so long a you open the valves fully and don't close them until the test fluid is flushed out there should be no real issue. The valves well be exposed to dirt in their working lives so a bit at the start isn't fatal. If the valves are welded then you end up with too many untested welds.

There is a lot of rubbish talked about what you must and must not do during hydrotestingg but most of this is simply custom and practice of the individual or company. The only thing you need to do is follow the code requirements.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[bgswartwood]

We test with the valves installed, 1/4 open. This allows for equal pressure around all surfaces of the ball and seal to prevent damage.

 

[BigInch]

That's OK if you absolutely must test it when installed, but not ideal, as it might allow dirt to get around and into the sealing regions on some valves. Keep the water clean.