Rust on SS weld

Hello all I have a problem with rust on my welds. First off, I am not a welder. I had an experienced welder weld 1/4" High Pressure SS couplings into the bottom of my brew pot. It has been about two weeks since this has been done. Now at first I didn't think anything of it because I was busy finishing the rest of my rig, and I had heard that welding SS on SS shouldn't produce rust. I also heard than if there was rust, then it should not really cause a problem but it seems to be slightly spreading. What can I do to remove this or any general information would help. Thanks.

Well I am no SS welding expert myself, but if I remember correctly, getting stainless too hot can change the properties stainless has (eg not rusting). Or there is also another possibility that maybe the incorrect form welding was performed. I once welded (MIG) some hinges on a stainless keg that I turned into a small charcoal grill which wound up rusting like crazy. Now this may not be the case in your situation, but is a possibility.

Try scrubbing with Bar Keepers Friend

Super heating stainless compromises the oxide layer that gives it it's corrosion resitance. You need to scrub it down to bare metal so that it can repassivate and you'll be good to go. Like the last guy said, bar keepers friend should work well.

Your welder may have used a contaminated wire brush on the welds.

When working with stainless steel you must use consumables(grinding wheels, wire brushes, etc.) that have never touched anything but stainless steel.

Can you post a picture? I could give you an educated guess as to why the welds are rusting.

After some other research, I read that, like BBLBrewer said, welding SS compromises the oxide layer that gives SS its rust resistance in the first place. I read to either treat the weld with chemical immediatly after welding or if waited a while a SS wire brush(only used on SS) should do the trick. And it has. Thank you. Here is a link for anyone with a similar question.

http://www.sperkoengineering.com/html/Rust.pdf

It's called sugaring... the chromium was burned out of the alloy during welding. Probably because A) it was welded too hot, or B) without gas shielding on both sides of the weld, or C) both.
You can fix it by running a angle grinder with a flap wheel on it, then polishing with appropriate wheels and compounds.
There is a lot more to welding stainless than just the equipment.

This is sugaring.

Sugaring occurs on the back side if a weld when there is no shielding.

I don't think that is what jmajor817 described.

dmfa200 said:

Your welder may have used a contaminated wire brush on the welds.

When working with stainless steel you must use consumables(grinding wheels, wire brushes, etc.) that have never touched anything but stainless steel.

Can you post a picture? I could give you an educated guess as to why the welds are rusting.

Click to expand...

This is also my guess, I can likely be fixed or greatly reduced my scrubbing it with barkeepers friend, which is an acidic slightly abrasive cleanser available at grocery or hardware stores or you can make a paste of citric acid powder (available at home brew shops) and water , and let that go to work on the welds and rust.