Still Studying... question about pre-qualified processes D1.1 Clause 3 1

[Sammy19]

Listening to some of the advice from my last post I have been working in the code and paying special attention to the 'notes'.

Figures 3.3 - 3.4, note 'a' in the legend on page 77 provides a stipulation that these joints are not pre qualified for GMAW-S, nor GTAW.

Buuuuut sub clause 3.2.2 states that these process are never pre qualified? What am I missing?

3.2.2 CODE APPROVED PROCESSES. ESW, EGW, GTAW AND GMAW-S welding may be used provided the WPSs are qualified in conformance with clause 4. Note that the essential variable limitations in Table 4.5 for GMAW shall also apply to GMAW-S.

Thanks again in advance.

 

[bb29510]

read the commentary on page 453

 

[Sammy19]

1. Thank you for the help. The code doesn't refer you to the commentary... I was putting that off hoping that I would have time to absorb the annexes / commentary after I pass the exams and start putting it all to use.

2. It still seems contradictory....

The first paragraph of C-3.2.1 specifically excludes GMAW-S and the fourth paragraph confirms and reinforces both sub clause 3.2.2 and 4.16.1.

4th paragraph:

The code does not prohibit the use of any welding process. It also imposes no limitation on the use of any other type of joint; nor does it impose any procedural restrictions on any of the welding processes. It provides for the acceptance of such joints, welding processes, and WPSs on the basis of a successful qualification by the Contractor conducted in conformance with the requirements of the code (see Cluse 4)

The commentary goes on to explain the technical mechanics of the process.... I have welded tons of thin metal with the GMAW-S process... that's all pretty straightforward. A scientific breakdown of how things work when a guy like me "turns his SH@$ down" so the metal doesn't twist into a potato chip.

Thanks again for any help I am just trying to wrap my head around this book. My intention is to show up at the seminar somewhat prepared. Having no serious professionals to turn to at work, I had to come here to have anything resembling an intelligent discussion about my questions. I seriously appreciate your time. All of you.

I feel that in this crowd I can learn a lot by focusing on where my assumptions are wrong, then working on figuring out 'how and why' I am wrong. Constructive criticism is entirely welcome. Please tell me why GMAW-S is not prequalified in the text portion of clause 3, but seems to be allowed on some of the prequalified joints in the figures portion of the same clause....

 

[48v]

Sammy19, I think note 'a' is simply reinforcing the previously stated rule. In the 2008 edition, it is listed for every prequalified GMAW joint. This doesn't mean that the joint designations without note 'a' have prequalified status with GMAW-S or GTAW, since they already specify the process as SMAW or SAW. I think a is just to help people out who read the prequalified figures but don't actually know the chapter. Of course, any joint may be qualified using GMAW-S or GTAW by testing. To your point about think metal, if it's less than 3/16" you can use D1.3 (less than 1/8" and you're forced to) in which GMAW is prequalified in any transfer mode.

 

[gtaw]

Clause 3 addresses the requirements that must be met to be exempt from qualifying the WPS, i.e., exempt from testing.

Any time all the conditions for prequalification cannot be met, the WPS must be qualified in accordance with clause 4, i.e., the contractor must demonstrate the proposed WPS will produce the required properties and meet the requirements for weld soundness and visual acceptance criteria.

Specific joint details include the note "a" indicating those specific joint details are not prequalified for GMAW-S or GTAW. I believe that means those specific joint details must be qualified by testing if the contractor wishes to use them in production.

Best regards - Al

 

[48v]

Gtaw, agreed. Alternately, the contractor may use processes that are prequalified, namely GMAW with a transfer mode other than short circuit (spray, or I suppose globular) or FCAW.

 

[gtaw]

Ditto!

Best regards - Al

 

[Sammy19]

Thanks again. That makes perfect sense. You wouldn't short circuit a Sub Arc....

 

[Mr168]

It has also been construed as placing additional prohibitions for GMAW-S and GTAW when qualified per Table 4.5, variable 31, which is the catch all "any CJP qualifies any groove detail conforming to...", e.g. if I qualify a CJP with GTAW, I get the joint details of 3.13 provided they are not prohibited per note a.