Welding Tips and Tricks

I am helping a friend build a fire pit for his backyard here in Arizona.
Essentially a 120x22” box 12” high made of 1/8 inch thick stainless steel sheets that will be supported inside by a mild steel frame made of 1 or 1-1/2 inch angle iron. There will be a 96x8” opening on top.
My friend asked me to TIG tack weld the sheets to the frame inside.
What kind of filler should I get?
And how can I advise my friend: what type of stainless steel to buy, or, what type to avoid. He will most likely end up buying pre-cut sheets because we don’t have the means to cut them.
I looked it up in the Machinery’s Handbook and it seems like 304 and 316 might be the most common types but is there something I need to know about an outdoor application and about welding stainless to regular steel? Thank you all.


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309 or 312 filler works best.

1/8” sheets (11ga) will turn into tacos when hot. They will come back some after cooling. But expect warpage while the fire is burning.

Thanks for the filler advice, much appreciated.

Should we choose thicker material for the top? 3/16 or even 1/4”? One would think that gets expensive quickly, but we will do what needs to be done.


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Just the nature of stainless. Personally, I’d use cooled rolled plate and not stainless. That’s up to you.

what you could do is make it out of steel and put stainless panels around it spaced off the steel a bit.
that would help with heat issues warping it and still maintain the look. you could also cut patterns etc into it.

309 is specifically designed for welding stainless steel to mild steel. 312 is designed for welding unknown grades of carbon steel.

Sorry to be a kill joy, but don't put too much work into the fire pit, they rust out and fall apart from corrosion if used constantly. Concentrate on aesthetics of the area, and put the effort into nice furniture.

weldin mike 27 wrote:309 is specifically designed for welding stainless steel to mild steel. 312 is designed for welding unknown grades of carbon steel.

Sorry to be a kill joy, but don't put too much work into the fire pit, they rust out and fall apart from corrosion if used constantly. Concentrate on aesthetics of the area, and put the effort into nice furniture.

id wager that was the impetus for stainless