pipeline pressure test

[Rosthorn]

What formula do people use to determine the volume of fluid (of a known compressibility) that is needed to bring a pipeline to a specific pressure for pressure test purposes?

 

[CSmith]

That's easy - work out the volume of the pipeline, then fill it with that much water. You shouldn't be using a gas for pressure test purposes.

If there is a defect in the pipeline (and if that wasn't a possibility you wouldn't have to test it) using an incompresible fluid like water will cause a much smaller crater/explosion than if you use a gas.

If I've misunderstood the situation, the mass of gas required is derived by using density = (MW * Pressure)/(z * R * T), then multiply by the pipeline volume.

Happy Testing

 

[zdas04]

A nifty rule of thumb for water tests is that it takes about the ID (in inches) squared number of barrels (42 gallon) to fill a pipeline. For 6,500 ft of 16 inch, the required water is:

16^2*6.5 = 1664 bbls = 70,000 gal

When I first heard of this rule I was skeptical so I went through a rigerous volume calculation and got about 6% less than the rule. When you add in requirements for irreducible tanker-truck volume and spillage, you get really close to ID^2/1000 ft.

We've had many (heated) discussions on eng-tips.com about using gases for static tests. The bottom line for me is that if you do your job properly then both ASME B31.3 and ASME B31.8 allow the use of gases for testing and they allow air tests in certain conditions up to hoop stresses that are 75% of SMYS.

Environmental concerns over hydrostatic-test-water disposal, difficulty in dewatering lines, and weight considerations have all caused me to preferentially perform gas tests in nearly every case (50+ gas tests over the last 15 years).

David Simpson, PE
MuleShoe Engineering

http://www.muleshoe-eng.com

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

The harder I work, the luckier I seem