Flaws in Gas injection molded parts

[s raju]

Dears,

We are molding many gas injection parts, normally after molding we do pluging the gas inlet hole by ultrasonic welding.

Insome case there were poor welding or some crack due to welding pressure which creats a opening for liquid to enter into the holllow area. The liquid mentioned is used at our secondary operation.
For the welding failure and crackings are beeing countermeasured by design aspects, but my question is
How to identify this kind of flaws by non distractive method?
Is there any fool proof/inspection method to find the leak in Gas injected hollow parts.


Please get some inputs for me