Impact testing and heat imput

[REGRUMBLE]

We are fabricating vessels of 516-70 (P1 G2) with various thicknesses from 5/16 to 1" thick. The customer wants all procedures impact tested at -45C. Since impact values are directly connected to heat imput any change of the electrical characteristics changes the impact value of the test. These are supplementary essential and QW 409.1 indicates you cannot increase heat imput at all. My question is when does QW409.26 that indicates you can increses heat imputs in the first pass by 10% and when does QW409-29 which indicates that you can increase the ratio of heat imputs between the first and second layer by 20% apply. If I apply only QW409.1 I will need a new welding procedure for every thickness but if I apply the other two clauses I can cover a range of thickness with each procedure.

 

[metengr]

What welding process(es) is being used?

 

[DVWE]

QW-409.26 is specific to weld overlays.
QW-409.29 is specific to temper bead welding.

I'm guessing that neither one apply to you.

You should read QW-401.3. You don't need to do an entire re-qualification, just impact testing.

 

[REGRUMBLE]

To metengr we use GTAW, FCAW, GMAW and SAW the same variables apply to them all.
To DVWE; I did not realize that QW409.26 was specific to weld overlays and I do not know when temper bead welding applies since every bead tempers the one below it. Thanks for the tip on QW 401.3 but since our previous procedure was done on 1/2" plate without impacts we are still stuck with doing 7 more samples (X four processes) from 5/16 to 1" and have impact testing done on each one.

 

[DVWE]

Regrumble,

See QW-290 for temper bead welding requirements. I doubt it applies at all to your situation. This technique has to be qualified special on its own.

My point about QW-401.3 is that you do not need a full size test coupon, just big enough to remove the required specimens.

 

[metengr]

REGRUMBLE;
You can qualify a basic groove weld procedure for production for each welding process for the stated range of base metal thickness for impact testing - one coupon per process for impact testing. If you have existing weld procedures for the process, you can run a separate coupon just for impact testing.

 

[weldtek]

A little further - qualify for the worst condition.

Qualify impacts on the thinnest material with the highest heat input. This practice will reduce the number of tests required.
Of course you have to be able to live with the parameters you qualify so more than one test each utilizing different parameters may be necessary, but, the thickness range you mantion is not that wide.
If you already have a PQR covering 1" thick material it may be possible for you to qualify impacts only on 5/16" thick material and cover all the way through 1".