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Up Topic Welding Industry / General Welding Discussion / GMAW-P on Duplex pipe
- - By welder5354 (**) Date 06-23-2008 02:33
Just wondering, if anybody out there has done GMAW-P(pulsed) on Duplex or Super Duplex pipe.
I would like to know, if you had good results.  A company i work for has a contract to fabricate
6in sch. 160 duplex piping and would there be any advantage to using the GMAW-P for faster spooling. 
Would like a little feedback.  Thanks
Parent - By cmays (***) Date 06-23-2008 02:49 Edited 06-23-2008 02:55
Are you running a GMAW stringer? If so we run 3/16 gap GMAW stringer 0.35. Depending on your machine you will be around 240 ipm and 18 volts I think. Ive got both Lincoln power mig and XMT304s and they will run completely different.  Hot Pass and fill are GMAW-P 0.45 about 260 ipm and 1.08 trim. I put a two pass cap on and drop down to about 240 to get a nice comtrolable dime high puddle. For spooling its extremly fast. I prefer using a miller for stringer pass and Ill run the lincoln for all GMAW-P. Keep in mind this is "a" solution but not "the" solution.This is all  done on code work sch 160. I found that it helps to run a water cooled gun on heavy spooling with GMAW-P because it will smoke that gun.With different settings we run GMAW-P on alot of spooling pipe work were aplicable and have good results on all sizes and thicknesses.  Have a good day and good luck to you.
Parent - By pipewelder_1999 (****) Date 06-23-2008 11:46
The welding on duplex that has been using NiCrMo-3 for the filler metal. The roots were welded with GTAW and the remainder with GMAW-P. These welds were shop welds but made in position.

The pipe welds were only VT'd and PT'd and came out ok. The remainder of the product was 5/8" 2205 shell sections . All welds were flat, vertical or horizontal. The GMAW-P process was specified by the end user and we didn't hasve anything to compare it too BUT the process is prone to non fusion defects in my opinion if the parameters are not controlled.

Excess puddle size and to narrow of a groove was a killer.

If you are able to roll out the welds, I would think GMAW Spray would be better. Duplex has some issues with time at certain temps but I don't thing that would be a concern.

My experience with the material is only for a couple of years involved with scrubber fabrication so I think some more detailed advice may come.
Up Topic Welding Industry / General Welding Discussion / GMAW-P on Duplex pipe

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