April 21, 2014
Q: The company I work for welds with GMAW-S, and all of the weld procedure specifications (WPS) that we have are from prequalified AWS D1.1 welds. When I look in D1.1, I find that GMAW-S is not a prequalified transfer mode. Are all of our WPSs null? If I understand D1.1 correctly, we would need to have a procedure qualification record (PQR) for all of our WPSs because they are GMAW-S. Is this correct?
A: This is a great question! The short answer is yes, but I should clarify what I mean. When you mention GMAW-S, you are referring to short-circuit transfer mode (see AWS D1.1 Annex K, “Terms and Definitions”). You are right to note that GMAW-S use is widespread. You are also correct that GMAW-S is not a prequalified process per AWS D1.1. So what’s up with that?
AWS D1.1 is the Structural Welding Code—Steel. Its intent is that it is to be used for materials that are 1/8 inch or thicker. The concern by those who determine the requirements for prequalified procedures is that the short-circuit transfer mode has the potential to generate a lack of fusion. It has been my experience—after running hundreds of PQRs— that this lack of fusion becomes consistent in material thicknesses greater than 3/16-in. or in certain positions and progressions.
That’s not to say GMAW-S cannot be used with a prequalified procedure. AWS D1.3 is the Structural Welding Code—Sheet Steel. Its intent is for GMAW-S to be used with material 3/16-in. thick or less. Clause 3 of AWS-D1.3 details the requirements for developing prequalified weld procedures using short-circuit transfer.
AWS D1.1, Clause 1.2, “Limitations,” encourages the use of D1.3 on materials that are 3/16 in. thick or less. So using prequalified procedures for short-circuit transfer is possible; it simply has to be done to a different structural welding code.
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