Stud Welding

[Metalmeister]

When qualifying a stud welding procedure per AWS D1.1, using a particular manufacturer's equipment and set-up, may the subsequent stud welding WPS utilize any manufacturer's equipment with the same parameters? It is noted in ASME IX that a change in power source or stud gun model number represents a change in an essential variable. The AWS code is not so clear on that note.

 

[DVWE]

Although the suggested form in Annex M leads you to believe those variables are essential, they are not. The only items needed to be addressed when doing a SW qualification are listed in 7.6.7.

I am assuming that your application was not prequalified as per 7.6.1?

 

[gtaw]

Different codes, different essential variables.

Best regards - Al

 

[Metalmeister]

Thank you, DVWE, for taking the time to respond. You are correct, as this is not a pre-qualified situation.

So based on what is listed in ASW D1.1 Par. 7.6.1 and again for the manufacturer's qual test in 7.9.10, the arc shield, the combination of ferrule and flux, is an essential variable, and more important than power source and stud gun. Sounds like ASME Section IX is a bit out to lunch on this one.

 

[DVWE]

Sounds like ASME Section IX is a bit out to lunch on this one.

I don't necessarily agree with that, but I do agree with what gtaw has stated; Different codes.

 

[Metalmeister]

I have seen, respect and value previously posted comments from both you guys. Maybe I'm just becoming a bit old fashioned, but you would think that by the 21st century, Code rules would be more in sync to the real parameters/variables that affect the metallurgy and structural integrity of a welded joint.

Let me ask you a follow-on question, if I may. AWS provides instruction to qualify a given stud weld setup including current, time and arc shield, and to document that setup in the PQR. Except for arc-shield, it appears that there are no limits to current and time (or other critical parameters) that can be used in the subsequent field WPS provided that the daily pre-production test demonstrates a sat result. If that is the case, why bother with a qual test and required 90 degree bend and tensiles, if a 30 degree pre-production bend test is equally discriminating. Can you tell that I'm a bit lost in the technical logic of the AWS Code on stud welding?

 

[gtaw]

While I don't sit on that committee (AWS D1.1) and I am no way speaking on their behalf.

I can only say that the manufacturer has to qualify the stud welding operation. The upper and lower extents of the permissible current range are established by testing by the manufacturer. That information is provided to the contractor (end user) that is installing the studs.

The contractor installing the studs performs preproduction testing to verify the equipment and setting are capable of producing an acceptable weld.

One must also consider the fact that AWS D1.1 limits prequalification of WPSs to those materials listed by table 3.1. All other materials have to be qualified by testing. ASME Section IX deals with a wide variety of base metals, both ferrous and nonferrous, and does not have prequalified WPSs.

Best regards - Al

 

[Metalmeister]

Thank you gtaw and DVWE. Great response posts from both of you.

 

[Mr168]

If the question is whether you can use different manufacturer's equipment than that utilized in the PQR, the answer is yes. If the question is whether you can utilize different manufacturer's equipment without re-performing the pre-production setup testing, the answer is no.

 

[Metalmeister]

Thank you, Mr168. Your definitive answers are also very helpful to my understanding to the process and Code.