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Up Topic Welding Industry / Technical Discussions / Heat Input WPS??
- - By rtrautman (*) Date 04-18-2003 16:36
Our customer is recommending a Heat Input WPS for our processes. The Engineer recommended Max heat input on a 20mm thick piece and the Min heat input on our maximum thickness we use which is 36mm and this would cover our range of 8mm-36mm. Is this correct?? Also he referenced Table 5.2 in AWS D1.5 and this table states that if you don't conform to any groove detail in Figure 2.4 or 2.5(which we don't because we neither backgouge or use a backing strip) but you are still using the filler metals in Tables 4.1 or 4.2 then use Qualification option per subsection 5.13. 5.13.3 states essential variables in table 5.3
With all of that said my other question is would we have to do two PQR's(one at the maximum heat input on the thinner material and one at the minimum heat input on the thicker material) for each process that falls out of the essential variables of Table 5.3?

We use a SAW process with A709 Gr. 50 AWS electrode specification A5.17 Class F7A4-EM12K
Parent - - By CHGuilford (****) Date 04-19-2003 15:24
Being at home right now, I don't have D1.5 handy and I don't like to quote from it without it being in front of me. So I'll keep this generic until Monday.
First off, since your customer is making the recommendation, he/she will likely not have any difficulties in approving your PQRs as described. I would point out the disparities so that you are sure an informed decision will be made.
The minimum/maximum heat input tests are not uncommom; this option usually gives you the widest range of allowable parameters for your WPSs. Qualification under 5.13 seems to give a generous range also until your take a hard look at what is actually qualified. All looks easy until you factor in the Heat input allowance of -25%/+10% (or is it the other way around?) Either way, when you take your max volts and amps, you can't use the minimum travel because that will exceed the heat input allowance. The opposite way also is true with min volts/amps and max travel. The envelope is really very small.

You could do multiple PQRs under 5.13 to extend your ranges but the paperwork is a pain and not everyone will readily understand it should you wish to use it for another customer. Although, other customers may not accept qualification under 5.12 with non-standard joints either, but your chances are good that they will.
I'd say your customer is trying to help you out. The approving engineer may modify requirements of D1.5 for special circumstances.

Your 2nd question answer is yes, you have to conduct the tests for each process used. Variables are too great between the different processes to allow, for example, a SAW (sub-arc) PQR to qualify a SMAW procedure.
Hope this helps,
Parent - - By rtrautman (*) Date 04-20-2003 15:07
Would you need to do a Heat input PQR for each bevel configuration or can you Qualify each bevel configuration and do a Heat input PQR for all??
Parent - - By CHGuilford (****) Date 04-21-2003 13:46
Not trying to be flippant here but from your 1st post, it seems like the engineer is very willing to work with you. Maybe you should run the question by him/her?

Otherwise, I would say that if your bevels vary significantly, you would have to do a test for each. By "significantly" I mean exceeding the typical tolerances listed in Figure 2.4 for similar groove configurations.

I have to wonder though, just how non-standard is your weld joint? In almost every situation, I have been able to use one of the standard details and tolerances for our work. So I'm wondering if you really have a non-typical joint or if you could make some changes to make them per Fig 2.4?
Chet Guilford
Parent - - By rtrautman (*) Date 04-21-2003 13:57
Well the only difference between our joints and the ones in 2.4 is that we don't backgouge or use a backing strip. The SAW process we use penetrates enough to burn out any inclusions from the other side. Our customer wants us to prove this by doing new Heat input WPS/PQR's. So in my assumption without the backing strip or backgouging this would put us out of 2.4
Parent - - By CHGuilford (****) Date 04-21-2003 17:05
It takes me a while but eventually things will sink in. It sounds like you're welding a plate girder with the web vertical and 2 sub arc heads, one on each side of the flange/web joint, to make a CJP weld.
If that is the case, I can see why the engineer would recommend the max/min heat input test. He wants to be sure that there actually will be complete penetration at the lowest heat input.

Now, I have seen such welds being made but I have never actually welded them. So my question is, since you are using SAW, which is usually very smooth and consistent, do your parameters vary enough to be a concern? Could you run a PQR under 5.13 to qualify the roots and then use an existing PQR for the remainder of the weld (for a WPS qualified with 2 PQRs)? That would be like welding with backing for the fill and cap passes and you would have more flexibility for other WPSs.

I assume a no to this question but I'll ask anyway. Will the engineer accept a full thickness mock-up joint welded with your lowest heat input for the root, from an established PQR/WPS and do UT and macroetches?

It would seem that you will want to use your test results for future work, so in that case I believe I would push for the 5.13 PQR after all. If the engineer is concerned about poor penetration, you could draw up a chart showing what is actually allowed by the 5.13 test. As I mentioned before, the parameter window allowed is pretty small.

Hope it works out for you, I'd appreciate you keeping us posted.
Chet Guilford
Parent - By jwright650 (*****) Date 04-22-2003 13:10
Please do keep us posted on this, I haven't had to deal with this yet and I could file it away for future reference. Thanks,
John Wright
Up Topic Welding Industry / Technical Discussions / Heat Input WPS??

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