ASME IX Qualified thickness and group numbers with CVN 1

[JasonLouie]

Hello,
I am trying to figure out qualified thicknesses and group numbers for weld procedures qualified with impact testing.

1) PQR #1 was done on P1Gr1 to P1Gr1 on 1.5" plate, tensiles and bends only. PQR #2 was done on P1Gr1 to P1Gr1 on 0.249" plate, impacts only.

QW-401.3 states that only the minimum thickness is affected so these two PQR's are qualified for 3/16" - 8" with impacts requirements? (I've seen an interpretation which says that you don't need a PQR to bridge the gap between 1/2" - 5/8")

2) In addition to the two PQR's above, PQR #3 was done on P1Gr2 to P1Gr2 on 0.249" plate, impacts only. With the addition of this coupon, is the weld procedure qualified for P1Gr1 to P1Gr2 weld procedure for 3/16" - 8" with impact requirements? (this is what the vendor has sent me)

3) I have been reading Section IX carefully and it seems that this weld procedure is qualified for P1Gr1 to P1Gr1 3/16" - 8", and P1Gr2 to P1Gr2 3/16" - 1/2". Is this correct?

4) If impact tested PQR's do not affect the maximum qualified thicknesses, why do I get weld procedures with PQR's impact tested at 0.249", 1/2", and 1.5"? Wouldn't one PQR impact tested at 0.249" qualify all thicknesses?

Thanks...this is a lot for my brain to sort out on a Friday afternoon.

 

[vesselfab]

the pqr qualifies the actual welding procedure range, but the each pqr will qualify a lesser range for impacts.

a wps qualified 3/16" up to 8" by the original pqr if tested say on 1.5" plate and did not have impacts run

now later on down the line they decide they need impacts on a job that's 1" thick so they drag out a piece of 1" plate and rerun the procedure. It qualifies for impacts 5/8 to 1"
5/8" is the lower limit on impact pqrs for thicker plate and 2t is the upper limit.

now they want to do another job thats 3/8" or 1/2 so they get a pice of 1/4" plate and run it for that range up to 1/2"


see, even though it is the same weld procedure and qualified in the non-impacted condition 3/16" to 8"......when you add in the impact requirements....you have lower the range of qualification


tha't is just as confusing a all get out.
wish i was a better writer

 

[metengr]

JasonLouie;
You do have a lot of information to sort out. First off, WPQR's are not qualified, they are certified records that are developed to qualify welding procedures.

You should be reviewing the Welding Procedure Specification(s) that were submitted along with the supporting WPQR's.

Go back and carefully review QW-401.3 in Section IX of the ASME B&PV Code. If a WPS was qualified using the essential variables w/o impact testing, only one coupon needs to be generated using the "same essential variables" and including "supplementary essential variables". In this case, the minimum base metal thickness for the revised or new WPS w/impact testing will be dictated by QW-403.6. However, the maximum thickness for this WPS will now only be 2T of the coupon thickness that was generated for impact testing. The reason is that the "same essential variable" ranges were not followed. If the impact testing coupon was 1.5" thick, the maximum would be 8", however, the minimum base metal thickness value would default to QW 403.6.

Makes sense?

 

[JasonLouie]

Thank you very much vesselfab and metengr!

I initially restricted the weld procedure to be used on base metals 3/16" - 1/2", but the vendor came back to me and quoted QW-401.3 saying that since only the minimum thickness is modified, their 0.249" impact coupon qualifies them up to 8". This didn't make sense to me, but when I read QW-401.3, there seems to be a loophole. Even QW-403.6 only talks about minimum thickness, and not that the impact coupon maximum thickness is dictated by QW-451.1.

Is there something I am missing? I could only find QW-403.5 which talks about group numbers and having the same essential/supplementary essential variables, but I can't find anything on qualified thickness.

 

[metengr]

JasonLouie;
I don't believe there is any loophole. The statement in QW-401.3 regarding use of an existing weld procedure that was not qualified with notch toughness (impact) could be used qualified for notch toughness provided another coupon is used for impact qualification without requiring tensile and bend testing. This is what that means. With a second coupon dedicated for impact testing, you still need to use the "same essential" variables, and this includes the essential variable ranges to maintain the original base metal thickness procedure qualification, using your first PQR that was certified using a 1.5" thick coupon. Otherwise, the new WPS will only be qualified to 0.498" for impact using the 1st WPQR and the impact testing coupon.

 

[JasonLouie]

Thanks metengr. You always have excellent advice!

 

[weldtek]

JasonLouie
Carrying this just a little further, I would point out that the essential variables aren't typically the problem, but the supplementary essential variables could be. In the example you give the .249" thick plate with impacts may qualify for the full thickness range, through 8", when combined with the 1.5" test plate, but, how practical it will be to weld thick material using the maximum heat input used on the 1/4" (nominal) thick test plate is quaestionable, to say the least.