RT Quality for Pulse GMAW welds?

By jwright650 (*****)

Date 05-09-2007 12:15

You have a PQR backing up this procedure that includes RT testing....

By NDTIII

Date 05-09-2007 13:00

What exactly is his concern? Mybe he is confusing it with short-circuiting mode. In the short circuiting mode RT is not a good choice. AUT is the preferred method of inspection.

By cryogenicshaun (**)

Date 05-09-2007 13:24 Edited 05-09-2007 13:26

a pulse spray method will produce RT quality welds. You will possibly need a backing of some sort. We use a ceramic backing strip with our auto pulse spray welds on our vessels.

By pipewelder_1999 (****)

Date 05-09-2007 13:59

It is similar to many other processes in the fact that it is sensitive to the operators. Our customers actually request it. We use GMAW-P for welding NiCrMo-xx filler metals. Our success has been good and the areas where we have problems are often related to the parameters and positions being welded and the technique used by the welder.

Our machines are synergenic which I do not care for so they can be a pain to adjust for filler metals not pre-programmed.

By Lawrence (*****)

Date 05-09-2007 14:39

John,

The GMAW-P is a "spray transfer" mode so your RT will look like any other spray transfer weld.

If you are using the RMD (Regulated Metal Deposition) function of Pipe-Pro for open roots. than it is a Pulsed *Shrot Circuit* mode and not a spray transfer type GMAW-P Short circuit GMAW on open roots is nothing new and RMD really is a production advantage, especially if your doing out of position or non-rotated open roots.

PipePro is one of the new generation of GMAW-P power supplies that actually produces as advertized... Even Ed Craig likes it for open roots.

If your welding plain carbon steel and not doing open roots PipePro is unnecessary. FCAW will out produce GMAW-P out of position

The GMAW-P on stainless and aluminum are amazing with the technology in PipePro and Axcess, PipePro being engineered with manual welding in mind and Axess built to sustain high speed automation.

Tell us more about the application

By jwright650 (*****)

Date 05-09-2007 14:42

Lawrence,
That was the point I was hoping to convey. The customer shouldn't have any problems accepting something that has a PQR and also has RT's to prove that it can be done and pass RT.

By jon20013 (*****)

Date 05-09-2007 16:01

Lawrence, the reason we are using GMAW instead of FCAW is because the product requires impacts. The weld will be from both sides but the bulk will be from OD side.

By Lawrence (*****)

Date 05-09-2007 16:24 Edited 05-09-2007 16:27

Sounds like you have it covered. The PQR proves it.

But for solid wire GMAW-P I still say PipePro is overkill....

Miller 350P could likely do the same job at less than 1/3 the cost for the power supply. But if you ever plan to do those open roots with RMD than PipePro is awsome.

By js55

Date 05-09-2007 17:25

Jon,
What's the material? What's the impact requirements?

By CWI555

Date 05-09-2007 18:05

The choice of NDE method does not make a quality weld, proper welding procedures and welders make a quality weld, the NDE only reveals the presence of or lack of discontinuities which may or may no be detrimental to the final product.
If you have a validated PQR/WPS and trained/qualified welders, and RT of the PQR to back it up, I don't see the problem.

By js55

Date 05-09-2007 18:40

I'm guessing your customer has read somewhere about reduced heat input and pentration with pulse as opposed to spray and therefore his grave concerns. However, they are unwarranted, given a proper WPS and adequately skilled welders as Lawrence mentioned.
If, and its a big if, there were an issue I think as NDTIII made the point, it would be a fusion problem, similar to SC, and RT is probably not the best choice anyway.
And that's not to say that you would be remise by using RT as opposed to AUT.
But were you to verify your qual with UT you could certainly buttress your argument for viability.

By jon20013 (*****)

Date 05-09-2007 19:05

js55, the material is SA-516, Gr. 70. Impacts are 50 ft/lbs absorbed energy, 35 mils lateral expansion (minimum) per NB-2331. Temps for testing are 0F.

By js55

Date 05-09-2007 19:45

Jon,
If I may, I don't think your problem would be the Charpy's with FCAW. ESAB has an excellent 71T-1 that routinely hits better than 20 @ -50. I used it exclusively in my nuky quals intended for SA-333 Gr 6 (also tested at -50). The weld metal never failed. What I would beware of is the HAZ/UBM comparison with SA-516-70. Your 516-70 may stop a hammer at 0deg. Esepecially on a 180 Ft/lb machine. See if you can find a 240. 516 is terrific stuff, with fine grains. And with hammer stoppers you have no nuke qual. Unless your qualing to the new Edition Section III.
The old Section III's are merciless, based upon old steel making technology. I mean, 40 years ago nobody much saw hammer stoppers at low temp. Not on 240's.
I had to drive the temps down to get the specimen to even break so that I had data. And even then I was hittin mle's in the low 90's, AND FAILING, because I couldn't beat the BM. The typical was like 90, 92, 89 for the HAZ and 92, 93, 91 for the BM. Thats a failure. A FAILURE!! Under the old Editions.

By js55

Date 05-09-2007 19:49

Keep me posted on how it goes. It was actually Walt that woke me up from my blind stupor on 516. Best materials guy I know.