Hydrotesting and Leak testing piping systems
Hydrotesting and Leak testing piping systems
(OP)
We are currently completing the final stages of a build programe for a separator unit. The vessels have been designed to PD5500 and are PED compliant (CE marked)and fully hydrotested. All interconnecting pipework has been individually hydrotested (ASME B31.3)1.5x design.
The complete unit is now assembled (vessels and pipework) and we want to carry out a leak test to demonstrate the joint integrity before sending offshore. Is there a definitive answer on which pressure the system should be 'leak tested' to? I hear 1.1xworking pressure, 1.1 x design pressure, 25% of the design pressure etc and not really sure which approach to take on this.
Any advice would be appreciated.
The complete unit is now assembled (vessels and pipework) and we want to carry out a leak test to demonstrate the joint integrity before sending offshore. Is there a definitive answer on which pressure the system should be 'leak tested' to? I hear 1.1xworking pressure, 1.1 x design pressure, 25% of the design pressure etc and not really sure which approach to take on this.
Any advice would be appreciated.





RE: Hydrotesting and Leak testing piping systems
David Simpson, PE
MuleShoe Engineering
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RE: Hydrotesting and Leak testing piping systems
I've seen nitrogen testing at 90% of design which was initially a bit scary until you realise that it's going to be working at that pressure normally. The real thing to do is that apart from the really strong stud bolts, any leaks are identified, system de-pressurised and then re-made and tightened up. Small 1/2" screwed NPT instrument taps are notororios for being screwed in wrong and then shooting off killing people when being tightened, but I think you are right, much better to check those joints not hydotested before it goes offshore, but a little surprised this wasn't listed in the company specs or scope of work.
31.3 345.5 refers to pneumatic testing which limits to 1.1. x design and 345.5.5 states reducing to design pressure before "eaxming for leakage". Given your pipework is 31.3, this may be the best to go for.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Hydrotesting and Leak testing piping systems
In the end I went for the 1.1 x operating pressure for 30 mins and seemed to be fine.
Cheers agaian.
RE: Hydrotesting and Leak testing piping systems