Air pressure test and air tightness test
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Due to its own reasons, a piece of equipment does not undergo a hydraulic test but does a pneumatic test. If it is according to the standard, the equipment must also undergo a leakage test. If it has already undergone an air pressure test, does it still need to do a leakage test (air tightness test)? Why? Is there a clear statement in the standard?
Relevant specifications that mention this issue：
The air pressure test does not require a safety valve. If a safety valve needs to be installed on the equipment, an air tightness test needs to be done after installation.
The air pressure test is a type of pressure test and requires strength verification, while the air tightness test is a type of leakage test. The properties of the two are completely different.
It’s explained very clearly in GB150, and you’ll understand if you read it carefully. There is a difference between hydraulic pressure test and air tightness test. The main difference is: 1. The purpose of the test is different. The purpose of the hydrostatic test is to test the strength of the container or pipeline; while the purpose of the air tightness test is to test the overall tightness of the container or pipeline. For example, when containing extremely and highly hazardous media, an air tightness test must be performed after the hydraulic pressure test. 2. The test pressures are different. The pressure of the hydraulic test is higher than that of the air-tight test, and the air-tight test generally takes 1.0 times the design pressure. 3. Normally, the air tightness test is conducted after the strength test (hydraulic pressure test) is passed.
GB50517-2010
For those of you who can check the standards, I’m sure you are all professional and good people, much better than the average person, so I didn’t check them.* I'm used to it, because I think it's not too troublesome to do it. If there is a slight leakage and the equipment is large, the pressure drop will be minimal, but slight leakage is not allowed.
The pressure of the air pressure test is higher than the pressure of the air tightness test. Therefore, if the air pressure test is passed, there is no need to perform air tightness again.
Thank you everyone for your answers. There are two voices. Please feel free to express your opinions.