piping leak test

[petroabbes1980]

Hi gents;
anyone can help me to get an information about the leak test,
is there any standard, guideline , etc. that show how to select between N2 and N2He to find the leak.
I know that this is related to the predefined leak rate, but I want to find the method based on the service (gas, cryogenic, pressure rates, etc)

 

[Strong]

Google: nitrogen tracer gas pipe leak testing methods

Walt