American Welding Society Forum
Can a single V WPS be used to weld a square groove joint,if all other parameters are followed?The code is ASME sec.VIII div.3.
No. But under ASME the groove type is a non essential variable so all you have to do is re-write your WPS to accomodate the change in groove and then you can weld it.
The WPS has to state exactly what it is you are doing. It is the instructions for what you are doing. However, spend some time with ASME IX and learn what the variables mean.
I would add to Jeffs post and say you need to take care with this situation in that switching from a v groove to square groove can run into penetration problems.
Yes you can write another WPS, but typically the AMP/Volt/travel Speed etc has to be altered to get the punch needed to get to the root. (Assuming equal as the V groove)
Those things do usually = an essential variable change.
Volts, Amps, Travel, Wire Feed Speed, groove details, use of backing, etc. are considered to be nonessential variables per Section IX unless toughness is a requirement per the construction code, i.e, Section I, Section VIII, etc. So, all that is required is to edit the existing WPS.
Best regards -Al
You are correct Al. Most of the codes I've worked to in the last several years do require toughness test. However, many do not. Thanks for the reminder.
It is easy enough to forget what is and what isn't an essential variable when you work with several different codes. While the multitudes of welding standards share many similarities, there are peculiarities in each.
Best regards - Al
You're right about that.I know our local AI (even though the vessel isn't stamped),and I have a call into him to make sure I'm legal.
They are going to have a AWS accredited shop do the impact tests on their sample.The joint in question is a bellows assembly that is only .006 thick,and will be vaccum tested.It's for a national lab,so I figured I would ask you guys about the WPS.
Thanks for the reply Gerald,I figured since the joint geometry was a non essential variable (as Jeff stated)it would not effect the procedure.Also,The WPS is from the prime contractor,and the company that contracted me to do the visuals is the sub contractor.I told them that they would have to qualify their own WPS,and have a PQR to support it,but the prime contractor told them to use their WPS.I just don't want to be hung out to dry if something goes south.
If I may, non essential variables do not mean they do not effect the procedure. What it means is that ASME Section IX assumes you will achieve adequate fusion and if so, minimum tensile strength and bend ductility will be acheived. The assumption is that fusion or lack thereof, or other discontinuity problems, are performance issues and not a procedure/mechanical viability issue. This philosophy, running counter to that in AWS D1, I happen to agree with. If fusion is achieved the minimum required strength and ductility will be acheived regardless of groove configurations. In which case all we are really talking about is fusion zone angle. There may be a measurable variance, but not enough to drop one or the other below the specified mins.
I do however have a mild disagreement with ASME IX on groove configurations and impact toughness. Though making groove configuration a supplementary would require and entire overhaul of the CVN system in order to be consistent, IMO. And to even begin such a huge task it would be incumbant upon one to determine if there have been failures associated with this issue.
I personally have read nor heard of none.
I have read that before,and find it odd that ASME and AWS differ on procedure joint design.as far as essential or non essential variables.I have to go over there tomorrow,and try to make a case to them to try and qualify a square groove.Since they have to send the sample out for impact tests anyway,they might as well qualify there own procedure.
Not so odd that ASME and AWS disagree considering ASME and ASME, and AWS and AWS disagree. Not so odd considering members within their respective committees disagree.
Yea,and they leave it to us poor souls to try to interpret their codes.
Committee members try as hard as they can to realize an understandable code requirement. In fact, out of all the priorities under consideration I think this one is tops. But, it just doesn't always work out that way. It ain't easy. And so yes, we are left to try and make it work.
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