Unfortunately my "stainless welder" just bought a new MIG (with voltage capable of welding stainless) and bought his first bottle of Helium+Argon+CO2 blend, then opened a brand new spool of Harris stainless wire. -Yes, despite prior claims it certainly seems like this is the first time he's welded stainless.... ;-(
My HLT is a 20 gallon Chinese "stainless" kettle; although not magnetic, it's clear that it probably doesn't live up to the 304 standard.
We put a slightly less than 2" hole in the kettle using a drill press and a hole saw (made quick work of it; we used WD40 as cutting oil) then cleaned up the barbs with a dremel quickly. Then used "coleco" clamps to hold the short 2" TC over the hole, then after calibrating the power output and wire speed of the welder until it "sounded like cooking bacon" and would lay a smooth bead, tack welded the TC ferrule on in 4 places so that we could remove the coleco clamps and properly weld all the way around.
-I should also add that the kettle and TC were quickly cleaned with acetone although I DID later touch them with my hands and may have gotten some oil on them.
The welder didn't backflush the vessel with gas at all and just relied on the GAS coming out of the MIG. The welds started out black and that didn't really ever go away. It was VERY difficult to get the welds right at the base of the kettle / TC fitting because the fitting was so short, we ended up with some REALLY hot glowing red weld sections and significant discoloring of the kettle around the welds, even the TC fitting itself darkened slightly from the heat. A HUGE "dallop" of liquid metal ended up in the wrong place -honestly I doubt a clamp would even fit over it (that bad).
I left it with the welder who says he's going to fix it up. (Grind back down the welds, stainless brush it, clean it with acetone and fix the remaining welds - he even threatened to weld a bit from the inside out.)
He's blaming this on the fact that the Chinese SS is probably a different alloy; I'm pretty unhappy about the whole thing but at least it's only the HLT.
He did the Boil Kettle yesterday which is proper thick American 304 stainless with a long 2" TC and he says that it went flawlessly, so we'll see how it looks when I get it.
My question: What should I do when I get the HLT / Kettle back to try and clean the weld as good as possible when I get it?
Should I wire brush and give it a scrub of Bar Keeper's Friend and then give it some sort of acid wash?
I really hope the kettle looks 3x better than the HLT...