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296 views
05:31 Aug-30-2004
Tim Milligan
Helium leak testing

Can anyone settle an argument regarding helium leak testing? We regularly weld titanium parts and duplex parts. NDT is usually by means of dye pen and helium leak test (low pressure, wiith vacuum on one side of the weld and helium on the other).
Is the helium test invalidated if the dye pen is applied before carrying out the leak test?


 
09:02 Aug-31-2004
Jim Knowles
Re: Helium leak testing ----------- Start Original Message -----------
: Can anyone settle an argument regarding helium leak testing? We regularly weld titanium parts and duplex parts. NDT is usually by means of dye pen and helium leak test (low pressure, wiith vacuum on one side of the weld and helium on the other).
: Is the helium test invalidated if the dye pen is applied before carrying out the leak test?
------------ End Original Message ------------

Essentialy, Yes, the reason is that when Helium testing like what is described, the penetrant liquid is viscous material and would block any small leak path to the detector. It is required that the part is Helium tested before PT, or the part can be vacuum degassed after PT, usually at an elevated temprature to aid in the boil off of the penetrant.



 


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