This has been interesting. There are some things that you take for granted because that's how you have always done it. It is good to be forced out of your comfort zone once in a while. This question forced me out of my comfort zone, so now I'll play the Devil's advocate.
Assuming you and some others are correct in your position that the groove detail is not an essential variable for welder qualification. Consider the following:
The welder is qualified using FCAW on a CJP grooved joint, 1-inch plate, all positions, the joint is a double-sided V-groove where back gouging was used to ensure weld soundness. Based on your assumption, the welder is qualified for all grooves and fillets, all position, including pipe over 24 inches in diameter, unlimited thickness.
Now the welder is assigned the task of welding a joint that is 1 1/2 inch thick with a single 60-degree groove angle and a bevel that is 1 inch in depth. The requirement is to produce a weld size of 1 inch.
Is it reasonable to expect the welder to weld such a joint? Yes, it is a standard prequalified joint detail.
Reduce the groove angle to 45 degrees. Can the welder be expected to produce a weld with the required weld size? The procedure was qualified with a 45-degree groove angle and it was CJP with BG. So, according to your line of thought the welder is still qualified and can be expected to produce the required weld.
Reduce the groove angle to 30 degrees. Can the welder still be expected to produce the required weld? Yes, it isn't an essential variable, so the welder should be able to weld it.
Reduce the groove to 15 degrees; still it is not an essential variable, so the welder should still be able to weld the groove as detailed.
Reduce the groove to 0 degrees. The groove angle is not considered an essential variable for welder qualification, so by all logic he should be able to deposit the required weld.
By now you should be saying, "Al, you silly Son of a Beach ball! No welder can deposit a 1 inch weld (joint penetration = weld size) in a groove that has a 0 degree groove angle and no root opening."
And that is my point. The welder is not going to be expected to weld anything that isn't either a prequalified joint detail or one that is qualified by testing. Even the WPS qualified by testing is a crapshoot. I've seen companies weld several test coupons before they got one good one because the joint details were simply ridiculous, but the code doesn't prohibit "stupid".
I have always advocated that the welding of a test coupon for qualifying the procedure is an opportunity to see what is reasonable and what is unreasonable. If the test coupons fail one after another someone has to step back and say, "Is it the welder, the joint design, base metal, what is the reason for the failures?"
If only one out of ten welders can weld a particular joint detail with consistent results that are acceptable, the joint detail is bad. If the joint detail isn't a prequalified joint, it makes sense to qualify the welders using the "poor choice" for a joint design. If the welder can weld it during qualification, it is reasonable to expect him to weld it in production. That is the one occasion where I can understand a contractor qualifying the welders on a nonstandard joint detail.
Unfortunately, D1.1 doesn't spell everything out for us. It cannot take into account every possible hair brained idea some contractor will come up with. They provide a means of qualifying the welders using a standard joint detail that is more restrictive than the prequalified joint details in figured 3.3 and 3.4. If the welder passes the qualification test for groove welds, he can weld any groove, any joint detail, etc. The catch is that if the joint to be welded isn't a prequalified joint, it has to be qualified by testing and the if the conditions set forth in Table 4.5 are exceeded, all bets are off and the procedure has to be qualified with the new joint detail that has been proposed.
I'm stupid, I freely admit it. It takes me a while to comprehend the words I've read, but eventually it sinks in. My motto, one of many, is "when in doubt, throw it into the Engineer's lap" and make him earn his big paycheck and let him assume the liability should something go horribly wrong.
This exercise has been both educational and humbling. I never imagine people would even consider administering welder qualifications that deviated from those specified by D1.1. I now must consider my position carefully, I may have to concede defeat.
Do you really think I’m going to buy into this hogwash, no way! ;)
No one has provided a logical path through the thicket of code provisions to delineate a means of supporting the position that the welder can be qualified using any test the contractor wants to administer, i.e., double sided welds with or without back gouging, single sided groove welds with any groove angle and/or root opening that suits their fancy. No, I believe the code is very clear on what welder qualification tests are to be administered if the ranges of qualifications listed in D1.1 are to be applicable. Clause 4.21 delineates the required tests and it refers the user to specific figures. It uses the verb “shall”, not “may”, nor are there options offered. I believe there has to be consensus by the Engineer and the Owner before the contractor can deviate from what is required and specified by D1.1.
Good God man, this isn’t ASME! ;)
As for the code interpretations, my limited experience has been that if a code interpretation affects the code, the change is made in the following edition. The last two code interpretations I requested have resulted in changes in the code language.
After reading this tirade, just remember who is writing it, and take some of my remarks with a grain of humor. ;)
Best regards - Al