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Up Topic Welding Industry / Technical Discussions / Maxiumum heat input exceeded
- - By Pssssst Date 06-17-2020 07:32
Hello everyone.

I want to ask you guys what should be done after finding out that a welder exceeded maximum heat input stated in approved WPS. Do we have to cut all the joint, clean all the weld included heat affected zone and reweld again? Or is there any way that we can do it without cutting the joint (run a new test with the same heat input values (or more) and perform CVN test to qualify the parameters that caused excessive heat input in the first place (assuming CVN test will be passed)?

Project according to AWS D1.1
CVN required
Base metal thickness: 20mm

Thank you.
Parent - By welderbrent (*****) Date 06-17-2020 12:56
This is going to depend upon several factors: When the temperature was taken that is declared to be above the max interpass (how long after the weld pass was made), where the temp was taken (as in how far away from the weld), the material grade, the end use of the members, and probably several more.

The object generally is that the inspector records and reports the condition and the engineer makes the call as to how to handle the situation.  It is not the contractors QC job nor the Owners Verification Inspectors job to make such a call, only to observe and report.  Then, let the welding lead know once the engineer responds to the RFI/NCR on how to proceed. 

You are dealing with CVN's which need added care.  The normally called out 'maximum interpass temps' are more concerned with the temperature before starting the next pass so the weld is held up until the temp is back down below max interpass.  With CVN's it can get more involved as the inspectors should have been more diligent in observing the process and not allowed welding to have kept going at an earlier stage so that maximum heat input, which is more stringent than max interpass, was not violated in the first place. 

At the end of the day, this was more of a QC and even QA lack of performance than one of a production failure.  But, a good production department would not have let it happen even without QC/QA observation. 

Have a Great Day, Brent
Parent - By 803056 (*****) Date 06-17-2020 14:43
Since you said the maximum heat input was exceeded, I going to assume that either the voltage, amperage, or travel speed was not within the ranges permitted by the WPS.

How was it determined that he was not within the stated ranges listed by the WPS. Was it a manual welding process and the parameters were observed while the welder was welding? Where the parameters varying while the welder was welding, i.e., the voltage typically bounces around as does the amperage as the welder moves along the length of the joint. Was it the travel speed that was the problem. With both manual and semi-automatic welding, it is typical that the travel speed will vary from one end of the weld to the other.

You left us with some questions my friend because you left out a lot of details.

If you want, you could requalify the WPS to incorporate the parameters the welder used. If the PQR is acceptable, the welds can be accepted. If the PQR is unacceptable, oops, the production weld isn't acceptable.

I would also bring in the Engineer to determine if the connection involved is required to meet CVN. Engineers and detailers, like all other humans, often take the easy route and call for all weld to be CJP when they don't need to be, call for all connections to meet CVN even when they don't have to because it is easier to write one note rather than identifying every connection individually and stating whether each requires CVN.

Question; where was the contractor's QC while the production weld was being deposited? Was this a one-off or were all of the weld deposited by this welder affected?

So many questions.

Parent - - By Jim Hughes (***) Date 06-29-2020 11:19
you left out some info. Load, seismic considerations, state or federal requirement, Joint, process, parameters. If this happened to me and my group today we would write an NCR and disposition accordingly. Might have to cut the weld out. Since this is D1.1 I can imagine this could be as simple as a fillet weld or as difficult as a moment weld. If it is possible a lot of times the simple solution is to just cut the weld out. Then train the welders on proper heat input. Or you could run another PQ with those parameters and perform CVN testing, but if it fails then your cutting the weld out anyway. Is your client in the loop on this issue? Do you have a welding engineer on staff?
Parent - - By 803056 (*****) Date 07-03-2020 06:39
Gee Jim and Brent;

No word from this fellow regarding some of the questions we raised. Funny how that works.

Happy July 4th.

Parent - - By welderbrent (*****) Date 07-03-2020 13:11
Happy 4th to you to Al.

Yeah, happens so often.  Never get a response back on our questions or advice.  I never get used to it.  

Have a Great Day,  Brent
Parent - - By Milton Gravitt (***) Date 07-03-2020 22:48
Happy fourth to everyone and be safe.

Parent - - By 803056 (*****) Date 07-04-2020 15:19
I was so despondent last night because all the fireworks were cancelled because of the Corona Virus.

I decided to make my own. I wanted to test one to make sure it would work.

I set a can of Campbell's Tomato soup on the front burner. Sure enough, in a few minutes there was thunderous explosion and a beautiful red cloud of color that seemed to linger in the air for several minutes.

Damn, it's going to take me hours to clean this kitchen.

Parent - - By welderbrent (*****) Date 07-04-2020 20:32
LOL!!  Too much.  Made my day brother.
Parent - By 803056 (*****) Date 07-05-2020 14:31
Happy to make you smile my friend.

Parent - - By Jim Hughes (***) Date 07-06-2020 13:36
Yep. it is somewhat frustrating. Try not to ask so many questions because it takes away from the spirit of tying to help someone. But with so much info missing even Sherlock Homes would have to throws his hands in the air. Had a great 4th. Want to give a special shout out to my neighbors that live on both sides of me. They fire power was impressive. I did not have to spend a dime on fire works.
Parent - By 803056 (*****) Date 07-06-2020 13:52
It was pretty quiet in my neighborhood this year. There were some occasional booms, but not as many as in a typical year.

Up Topic Welding Industry / Technical Discussions / Maxiumum heat input exceeded

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