PULSE ARC GMAW PROCESS DON KUMPUNEN

By pipewelder_1999 (****)

Date 10-20-2002 12:44

I have used the pusled mig process on nickel alloys and it was very helpful obtaining nice out of position welds however I think it is very sensitive to changes in the parameters and if not carefully controlled and leads to the same problems associated withh conventional GMAW. The FCAW process is more forgiving in relation to electrical changes.

I was in the Navy and we had welding procedures from PNSY, NNSY, and one other and there were procedures for GMAW-P and we even had 100S-1 wire on board. Neither of these were ever touched.

With 1/4" material and monitored welding, I couldn't imagine any problems but with GMAW pulsed, one could change the settings and have a nice looking weld with problems that aren't apparent.

Some excellent information is available at http://weldreality.com regarding the GMAW processes.

Gerald Austin
http://www.weldinginspectionsvcs.com

By DONK

Date 10-20-2002 13:33

GERALD,The 2 ship yards are BATH IRON WORKS and INGALLS SHIPYARD.BIW uses the pulse arc process.INGALLS uses the flux core process and there is a lot of over welding[1/8 inch weld size on each side of the bulk head.This causes a lot of weld distortion and warped bulk heads.This is corrected by a tremendous amount of flame straightening.I wonder what effect this has on the base metal?No one on the web sites want to address this problem.In my humble opinion the BIW ships delivered say 10 years ago should show some cracking,etc. if there is a hidden problem with the pulse arc welding.What do you think? DON KUMPUNEN QA SPECIALIST SUP SHIP PASCAGOULA

By Niekie3 (***)

Date 10-20-2002 18:33

Hi Don

Both the processes should give you acceptable results if the parameters are correct. Obviously each of the processes have their own strong and weak points.

The point that you made (in the other post) regarding the cracking that would be evident after 10 years if there was a problem with the GTAW-P, is only partially true. Certainly, if there was a fundamental problem that the process was unable to deliver the desired welds, then you should see problems by now. The problem is however that past success is no guarantee of future success unless there is extremely tight control of the welding. Often welders will modify parameters when you turn your back, because they are more comefortable with different parameters, or they get a nicer looking weld. In addition, one welder can have a much better technique than another. If this can happen, then you can end up with problematic welds that are welder dependent.

This situation is however not restricted to any single industry sector. As such, we should all be vigilant and ensure that procedures are followed. If this is the case, then I aggree that there should be little problems now if the ships have proven themselves over a 10 year period.

Regards
Niekie Jooste