Excellent series of articles. Thank you Al.
I have a couple of questions regarding prequalified welding procedures.
The first question is about the method of back gouging. I know from the joint detail (B-U4b-GF) that it requires back gouging but I can't find any info on required method.
My second question is regarding specifying stringer or weave bead. Again, where do I find this info to include in the wps?
Thank you.
-Kris
Occassionally one method will provide better results than another. But as to the "required method"...there is not one per the code. At least, as long as you are talking about D1.1. The options according to 5.15.2 are machining, thermal cutting, gouging (including plasma), chipping, or grinding. Generally you are free to use whatever is at hand and will perform the best given the position, space restrictions, material thickness, etc.
Generally the specifying of stringer or weave beads is not a major consideration. Where it becomes an issue is when the materials or code bring heat into consideration. A weave pass will add heat at a much faster rate. The only reference I can think of is in Table 4.6.
Have a Great Day, Brent
Brent,
Thank you very much. I have seen prequalified wps's with the back gouging method called out and was having a heck of a time finding where it was spelled out in the code. So when we produce a written prequalified wps is it a must to include the method of back gouging? And the same with specifying whether a welder uses a stringer or weave bead?
Thanks for everyone's help. I really appreciate it.
-Kris
D1.8 clause 6.7 is pretty specific about backer bars and backgouging.
You have read it before in several posts, but here it is again; codes list the minimum mandatory requirements. It is the manufacturer's/contractor's responsibility to take those steps necessary to ensure the construction of a structure is sound and safe and will perform as intended. To that end, in the case of back gouging, when it makes a difference, it is incumbent upon the manufacturer/contractor to address the means and methods in the WPS.
A good example of where the means and methods is restricted is in the case of quenched and tempered steel. AWS D1.1-2010, clause 5.15.2 restricts the use of oxygen gouging when working with Q&T steels.
Other conditions that may impact the serviceability of the welded structure must be considered as well. ASME construction codes and AWS structural welding codes do not address corrosion. It is the designer's responsibility to consider corrosion, corrosion rates, abatement, and prevention.
If toughness is a concern, heat input can be used to control cooling rates to mitigate the potential for grain coarsening in the HAZ. Issues relating to notch toughness are usually considered as "supplemental" to the normal requirements. That is, parameters that have an effect on notch toughness are applicable in addition to the normal requirements only when notch toughness is involved.
I am happy to see people are still reading the back issues of IT.
Best regards - Al
Hey Al,
Just wondering how come your Feb/2011 had so many more days than mine did?
