Essential variables in welding using GTAW process

[redandysafc]

I am working to ASME IX and have done a procedure to weld cunifer P34 socket welds using a purge but the client has asked for me to do a test without a purge. When I read ASME IX I think that the purge by QW256 GTAW that it is an essential gas but when you read QW 408 I am confused if it is QW408.5 OR .9 OR .10
Which one is relevant and is it an essential variable or not. ?????????????????

 

[metengr]

This is a terminology question;

gas backing (aka as purge) - applied to an open root weld joint on the side of the joint that is backing for welding to reduce oxidation. Welds with backing in place may be exempt for certain materials see 408.8

Shielding gas - required for any welding using GTAW to protect the weld metal from oxygen, nitrogen and hydrogen pick-up from the atmosphere

Now, go back and review QW-256

 

[weldtek]

Also, review QW408.5,.9, & .10 and look for things which make the paragraph applicable, or non-applicable. Eg. some of those paragraphs limit the aplicability to certain P #'s.

 

[tab1999]

Did you get the answer you were looking for?

It seems to me that if you Qualify a Procedure without backing gas, you can add at a clients request as a non- essential variable but not vice versa.