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I am considering building a stove out of stainless steel. I want to us stainless steel because the stove will have a double outer jacket to pass water through and heat it.

Will a wood fire sitting directly on stainless steel corrode it? Would a higher grade of stainless steel, say 316 instead of 304, prevent this?

Should the stainless steel be protected in some way, perhaps by a bed of fire bricks (at least) under the fire, to prolong its life? Or will stainless steel stand up to exposure to fire without corroding for a long time?

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  • $\begingroup$ Maybe I should have posted this in Engineering? $\endgroup$ – user2800708 May 18 '15 at 21:58
  • $\begingroup$ Yes, fire does corrode steel over time, though it takes time. Somewhere around several mm per year of continuous exposure. Steel is not a fireproof material. If the steel is cooled, the process is slowed. There are special steels tuned for boiler use. $\endgroup$ – permeakra May 19 '15 at 0:12
  • $\begingroup$ It its mm per year of continuous exposure, sound like I will be ok. This will only be used occasionally. $\endgroup$ – user2800708 May 19 '15 at 8:54
  • $\begingroup$ brief search revealed that if boiler tube is intended to boil, it should NOT be made of stainless steel. Special boiler steels should be used. $\endgroup$ – permeakra May 19 '15 at 12:05
  • $\begingroup$ Interesting, thanks. In my case I'm only wanting to heat the water for a bath (outdoors), 50C would be my guess at the maximum temperature. I suppose next to the metal it may get hotter, then mix in. If it boils it gone wrong, as the bubbles tend to disrupt the convection flow that circulates the water. $\endgroup$ – user2800708 May 19 '15 at 13:31
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A wood fire will not be hot enough to cause more than about 0.02" of metal loss in a year of continuous use. This is assuming about 1500 °F. It would make no difference if 410 (13 Cr - exhaust pipes) or 304 or 316 ss is used. If is has a complete water jacket, the life would be much longer.

Boilers are usually carbon steel; electric utility boilers have 1% or 2% Mo and maybe 1% to 2% Cr, not for oxidation resistance but for higher strength. With water in the tubes they are at a much lower temperature than the flame (roughly 700 °F to 1000 °F). However the wood will contain sulfur and other components that can increase oxidation rates.

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Here's a device that's been around for at least several decades, as far as I know:

water heater
(source: teploterm.ru)

I've been using something similar for around 15 years. The idea is you put firewood into the oven you can see at the bottom, and the chimney goes through a 90 liter water tank. The bottom is something like .5 - 1 cm thick cast iron, the rest is made from stainless steel sheet metal.

There are variants to the construction, but I think here are the two main points, coming back to your question:

  1. This thing needs replacement around once a decade, being in use around 500-1000 hours a year.

  2. If the stainless steel is thick, then rusting gradually becomes irrelevant. Does make the thing heavy, though.

  3. Yes, there is corrosion, especially around the fiery hot parts.

Also, note that the plumbing within this thing is kind of special, as it needs to refill cold water while simultaneously mixing your hot and cold water. I remember that it was very damaging to run it empty.

And yeah, this is more engineery than chemicky...

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Get a pad of steel wool. This is stainless steel, because it's made for use in a sink, washing dishes. Take a 9-volt battery and briefly touch both terminals to the steel wool. It will catch on fire. (Warning: don't try this at home, kids! But it totally will.) When the fire goes out, you'll be left with a pad of rusty steel wool.

Therefore, the answer is yes: fire can corrode stainless steel.

If your stainless steel is a big solid block rather than a super-high-surface-area pad of steel wool, the process will be a lot slower, but it will still happen over time.

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    $\begingroup$ Can you provide a source for the idea that most forms of steel wool are stainless steel? I did a quick googling and most steel wool seems to be something called "carbon steel", not stainless steel. $\endgroup$ – Curt F. Jul 7 '15 at 21:34
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    $\begingroup$ @CurtF. the dishwashing sort might be but tends to be made of thicker "wire" (actually more like strips) than the sort you might find with the sandpaper (NB UK bias). The latter doesn't burn with a battery, it gets red hot and melts, which can be use to ignite other things. $\endgroup$ – Chris H Jul 8 '15 at 12:57
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    $\begingroup$ Non-sequitur. Steel wool has tiny filaments, and the metal is vaporizing because there's a large surface area through which to transfer heat into the steel wool, so it melts and vaporizes. This doesn't imply stainless steel corrodes, or is oxidizing - and in fact one of the reason stainless steel is used in engineering is, it is resistant to many corrosive industrial chemicals. The battery+steel wool just tells you that with enough energy per mass, steel will melt and vaporize - as will glass, gold, titanium, silicon, or just about anything else. This is not corrosion. $\endgroup$ – charlesreid1 Sep 26 '17 at 6:28
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Not easily from what I can find. But remember it is Stain-less not Stain-impossible.

Actually there are different type of stainless steel used for different stuff. Like for protect it from fire I feel A typical composition of 18% chromium and 10% nickel, commonly known as 18/10 stainless, is often used in cutlery and high-quality cookware will be good.

Source: Wikipedia

If you see here fire pits are also made up of stainless steel.

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