contradiction in QW-256!!

[mirhosseini]

In ASME Sec IX, QW-256, change AWS class is supplementary and nonessential variable.
In QW-404.12 "change in SFA specification filler metall" needs requalification but in QW-404.33 this variable is nonessential.

I cant understand this contradiction. could you explain about it?


Regards
H.Mirhosseini

 

[metengr]

Each welding process has their own set of essential, supplementary essential and nonessential welding variables for qualifying a welding procedure.

QW 256 pertains to the GTAW process, and as such, has it's own specific list of essential, supplementary essential and non essential variables. Since 404.33 is listed as a non essential variable for the GTAW process you can substitute a different trade name filler metal or weld rod with optional suffix designators without re-qualification of the procedure.

If there impact testing requirements pertaining to GTAW welding, the change in AWS filler classification, as indicated by 404.12,would apply and require re-qualification of the welding procedure. The exemptions to this requirement are listed in a) through f) of 404.12.

The list of welding variables in QW-400 is intended to provide guidance for all applicable welding processes in the ASME B&PV code. So, you need to first determine your welding process and application, and then go back and follow the list of welding variables to qualify the welding procedure.

 

[llpcode]

First start by reading QW-200 and QW-400.

Essential Variables require requilification, while Non-Essential Variables do not. However, both must be properly addressed within the Weld Procedure Specification and Essential Variables must be addressed in the Procedure Qualification Record.

There is another item, that must be address whenever material toughness is required by the construction codes (e.g., Section I, III, VIII) and that is Supplemental Essential Variables.