Stainless welding didn't go so well: Cleaning it up?

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...


Adam

You would have been better off getting some one to TIG weld the stainless.. Regardless. Once you get them back, post some pictures so we can give you a better idea on what to do. Too hard to say without seeing the welds.

CoalCracker said:

You would have been better off getting some one to TIG weld the stainless.. Regardless. Once you get them back, post some pictures so we can give you a better idea on what to do. Too hard to say without seeing the welds.

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Thanks. Will do. I'll be out of the country most of this week but sometime early next week I'll get the vessels back, take some pics and post a link to them here.

-Appreciate it!


Adam

A lot of the Chinese stuff seems to be 400 grade stainless. It seems to rust much easier. Maybe your pot is made out of that?

assuming that he wasnt overstating that "flawless" commecnt about the boil kettle... it sounds like you (he) just figured out the difference between austenitic (300's grade) and other stainless steels (probably ferritic, like 430).

audger said:

assuming that he wasnt overstating that "flawless" commecnt about the boil kettle... it sounds like you (he) just figured out the difference between austenitic (300's grade) and other stainless steels (probably ferritic, like 430).

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No, we had much bigger problems than this. This is not ferritic stainless (non-metallic) it's just the cheap "whatever we have laying around we'll throw in the ladel" Chinese stainless. The weld had many, MANY problems the fact that the kettle itself probably wasn't 304 grade is way down that list.



Adam

Do not go back to that welder! He's feeding you BS! First off he should not be using MIG on 16ga material that will be used in the "food proccessing" industry. That alone tells you he doesn't know what he's doing. Second he should know to purge the backside to prevent sugaring wich will cause rust to form. You do not need high voltage for this either. You shouldn't need anymore than 50 amps.

"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)." Color is ok, it's the black you don't want. Even when done welding, the cup needs to stay above the weld providing Argon (should be 100% with stainless NOT MIX) until the weld cools to prevent O2 from creeping in the molten metal.

A lot of your stainless outdoor grills you see are actually in the 400 series. I wouldn't worry about this grade as much as the welds being done to it.

If you're ever looking for someone that does great welding, skip the local welding shop. Look for a food processing plant or brewery and ask who they used for the fab work. You'll always find someone who actually knows how to weld and they usually love the sound "it's for making beer".