Sealing tests are used wherever the pressure of the gas is different under operating conditions on the outer and inner surfaces. These are, for example, pressure or vacuum vessels, long-distance pipelines for gaseous and liquid media, storage tanks, piping, etc. The leakage test can be performed using various methods, e.g., helium method, pressure change method, bubble method,
Principle behind method
Leakage means an imperfection of any rigid interface – a joint that allows gas to penetrate through the pressure drop – gas, steam, liquid. These are defects that are geometrically small so they are not detectable by other non-destructive methods. Using this NDT method, we start from the fact that absolute leakage cannot be achieved and therefore the test is defined by the rate of penetration per unit of time. We distinguish two types of leakage testing: integral (determines leakage) and location tests (determines the location or estimates the size of the defect).