4 replies to this topic

[Danish John Paul]

Hi all,

 

I have a nitrogen bottle with 220 SCF capacity.

 

I want to test a segment of piping which has volume of 70SCF.

 

Client is asking if the N2 bottle full open can overpressure the piping.

 

How do I check if the Full N2 bottle capacity can overpressure a segment of piping?

 

Thanks

 

[breizh]

Hi,

I don't think the method is the right one to pressurize a pipe for leak test (safety reason), better to use an handpump and water to perform the test ( right pressure applied and duration ).

My view

Breizh 

[jayari]

The gas from the bottle will expand into the empty 70 cubic feet of piping and you can use an equation of state to see how much the pressure drops from increasing the system volume from just the volume of the N2 bottle to a system volume equal to the N2 bottle plus piping.

 

Most of the time, N2 bottles are used with a regulator directly connected to the cylinder that reduces the outlet pressure anywhere from 50 psig to 500 psig. Is that the case here to?

[latexman]

jayari,

One could physically do it that way, but as breizh said, there is a much safer way to do it by using an incompressible fluid, water. IF the pipe should fail during the test, compressed nitrogen could do a lot of damage by doing a lot of work on whatever is close to the pipe, like the testing crew. W = ʃ P x dV. With an incompressible fluid like water with dV ~ 0, there will be minimal damage and safety risk.

[jayari]

latexman - I assumed the OP has a reason to use GN2. Maybe they can use water and breizh has reminded them of this safer option. Maybe their system handles a chemical (e.g. semiconductor precursor molecules) that is violently reactive with water so they have to use a dry gas. Maybe the system is somewhere that doesn't have ready access to water that can be thrown away after use in an industrial application. Not many details in the OP, so anyone offering advice has to make assumptions. If you can do a hydraulic test, I'd agree that's likely to be the safer path.