Was PWHT done on this Pipe Weld?

[Guest102023]

6" schedule 80 (0.432) pipe, circumferential weld. A106, probably grade B. Weld made in standard fashion, E7018 fill passes.

Side 1: Carbon equivalent (per IIW) = 0.30; maximum HAZ hardness = 185 HV1 (1kg) ~90HRB
Side 2: CE = 0.40; maximum HAZ hardness = 180 HV1 ~89HRB

Any opinions on whether this weld was PWHT (required for service, not by Code)?? I cannot decide.

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"

 

[metengr]

What were the unaffected hardness values of the base materials for comparison?

Based on several EPRI documents related to CE affects (with values similar to SA 106 Gr B material) to establish new PWHT exemptions for ASME Boiler and Pressure Vessel Code for P-No 1 base materials, peak hardness of the weld HAZ for the 0.40 comparable CE value indicates PWHT was performed, rather than left as-welded.

Peak HAZ hardness values would be closer to 210 HV for the 0.30 CE base material and even slightly higher (225 HV) for the 0.40 CE base material, in the as welded condition.

 

[Guest102023]

Thanks, metengr. I think that settles it for me. The material is from a failure, 30+ years old.

Do you have the EPRI document numbers (if they are free issue)? I have in my library # 1008277 from 2004, 1011535/2005 and 1013554/2006. The last of those appears the most helpful.

The only thing I can add is that the microstructure doesn't look as 'sharp' as an as-welded structure might (very a subjective impression and possibly quasi-scientific I know).




"If you don't have time to do the job right the first time, when are you going to find time to repair it?"

 

[stanweld]

Based on your statement that E7018 was used, I would assume that this was a field weld, in which case I agree with metengr. If this was a shop weld, interpass temps can be quite high (>750F). I have most assuredly seen the stated HAZ hardness values in the as welded condition when interpass temps were so high. By the way, what was the weld metal hardness?

 

[Guest102023]

140 in the third pass, 175 HV1 in the cap pass. Given the configuration (it is near a bolted flange) I would be fairly certain it was a shop weld, although it was made in the 5G position.

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"

 

[metengr]

brimstoner;
What was the hardness of the unaffected base material? Your stated CE number for side 2 is on the higher end for what I have seen of SA 106 pipe material. Does this weld appear to be a SMAW or SAW weld?

Still lots of unanswered questions - which is why this type of internet chat can be inconclusive.

 

[Guest102023]

Side 2 is actually an elbow, CE = 0.40, BM ~150 HV1
Mean HAZ hardness ~165-170

Side 1 = pipe, CE = 0.30, BM ~165 HV1
Mean HAZ hardness ~170-175

The weld was definitely made by manual SMAW, 4 passes, 4 layers, although the root pass is unknown (most of it has corroded away in any event). The weld start is clearly evident at the bottom, and a wide weave was used in the cap pass, which is ~1 inch wide.


BTW, I am less dogmatically opposed to weaving than are many others. Provided the welder can reliably achieve sound deposits and limit interpass temps, there are tempering benefits to be gained from thinner, wider layers, especially for the low alloy grades.

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"

 

[stanweld]

With weld metal hardness that low, PWHT is most likely.