Plasma welding stainless pipe

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Hi guysI am plasma welding stainless 6" pipe 3mm thick for pressure in the 2G position. It is being run with 1.2 mm wire and 130 amps (pulsed). The problem we are having is the weld is coming out inconsistent and under cut on the top side (as shown in images attached).The welder seems to be hotter in the morning and the more welds we do the colder the weld gets. This is the first time I am using a plasma welding machine. I have tried a few different orientations too but the result have always been the same. Could you please suggest if there is something that I am doing wrong or is there any other way of achieving it?Thanks
Reply:Tig weld it Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:Absolutely unacceptable quality there. That's not considered stainless anymore after a cooking like that.
Reply:Originally Posted by SquirmyPugTig weld it
Reply:Originally Posted by Showdog75Absolutely unacceptable quality there. That's not considered stainless anymore after a cooking like that.
Reply:I've never plasma welded but do run automated gtaw orbital welders for a living welding x-ray tube. One simple observation is possible shielding gas issue as well as to many amps. Could also be to slow travel speed.Nice stainless welds will be gold or rainbow colored from as fast of travel speed with proper shielding gas coverage and amperage. Where are you located? How much you willing to pay for some trouble shooting?
Reply:Forgive my ignorance but what is plasma welding? I've never heard of itCraftsman 90 amp Arc welder
Reply:Originally Posted by lighttekkuForgive my ignorance but what is plasma welding? I've never heard of it
Reply:Originally Posted by lighttekkuForgive my ignorance but what is plasma welding? I've never heard of it
Reply:Originally Posted by MehulHi guysI am plasma welding stainless 6" pipe 3mm thick for pressure in the 2G position. It is being run with 1.2 mm wire and 130 amps (pulsed). The problem we are having is the weld is coming out inconsistent and under cut on the top side (as shown in images attached).The welder seems to be hotter in the morning and the more welds we do the colder the weld gets. This is the first time I am using a plasma welding machine. I have tried a few different orientations too but the result have always been the same. Could you please suggest if there is something that I am doing wrong or is there any other way of achieving it?Thanks
Reply:Other than the machine is sitting there, why plasma instead of tig?  If I remember correctly, the only plasma welder I saw uses no shielding gas - if correct, how will you obtain acceptable results without shielding gas?Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:Thats what I am thinking, what sort of air/gas is the plasma using?12v battery, jumper cables, and a 6013.I only have a facebook page. https://www.facebook.com/pages/VPT/244788508917829
Reply:.....I use plasma all the time for welding.Ian.
Reply:Originally Posted by puddytat.....I use plasma all the time for welding.Ian.
Reply:Are you using backup gas inside the pipe?                      Sincerely,                            William McCormick
Reply:Originally Posted by MinnesotaDaveThen for reference purposes, you should post a properly done stainless plasma weld for the guy. A few other properly done plasma welds on mild steel might help as well - maybe an open root with the front and back shown would be instructive.I'm curious to see what they look like.
Reply:Originally Posted by puddytatHi Dave....you already seen some of the welding pieces I posted on some other thread....nothing's changed after more than two years using it on and off.But I did do a cast iron job for a mate two weeks back and it was because the previous guy tried to tig it with cast iron rods and the mess just fell apart.....maybe he didn't have much experience, but he was in business so should have know how......I used mild steel with the cast and it worked out OK, and being a stressed item namely a clamp for a wood working machine, I'm pleased the job went so well.I have only done a small amount of stainless orientated welding with the plasma, and that was to add a stainless coating face to the receiver box on my car's towbar, and all I can say is it goes on the same as you would expect from plain steel welding.Despite what some have said, if you can't get a good weld with a plasma welder, you won't get a good weld on anything, it's that easy.BTW, if you did get a job that had been welded and was so daggy and definitely needed grinding completely out, try a plasma approach and you'll get success in five minutes flat.....no need to grind out the old weld......been there done that.Ian.