Tightness test
Tightness test
(OP)
First of all thanks for your attention. The client is requiring me a tightness test (which i understand is a type of pneumatic test) after hydraulic test of several pressure vessels. The design pressure for this equipment is 22 kg/cm2g and he says that this has to be performed at a pressure >= of this design pressure. Do you have experience with this type of tests and specially at this pressures? Do you know if this is acceptable due to safety questions and what measures we have to take?
Thanks in advance for your respond.
Thanks in advance for your respond.





RE: Tightness test
So your client wants "gas leak testing at a minimum pressure of 22 kg/cm2g" after hydrostatic test of the vessel? Is this additional testing part of your purchase order or contract with the client? If not, don't do it.
RE: Tightness test
Why? I see no purpose for a tightness test requirement if a successful hydraulic test had been performed. Also, there is indeed a safety issue for a pneumatic test at 22kg/cm2.
RE: Tightness test
1. Tightness test should be performed after hydrostatic test approval. Tight test pressure should be design pressure at least.
2. The test temperature should not below 5 ℃ for the of vessel which made of carbon steel or low alloy steel.
3. The gas of test should be clean, dry air, nitrogen gas or other inert gas.
4. To inspect all weld seam and connection by using soap bubble. No leakage can only be accepted. If leakage occur, vendor should perform
this test again after patch up the leakage.
Also they are talking about perform this test with the equipment painted. But i am still more concerned about the pressure of the test (22 kg/cm2g) than the issue of when to perform this test...
RE: Tightness test
In my opinion this thightness test is more to test for leakage at flanges as it is for welds.
Also if the vessel has been hydro tested, water still might block opportunities, which, because of the residing water, might not be exposed during the thightness test.
Have you considered a helium test in advance of the hydro test?
RE: Tightness test
Thanks all for your support.