Heat riser

Hello All

I have a question about heat riser materials. I've noticed everyone is going to stainless for the heat riser. I see the reason for this, but I have a piece of well casing I got from a drill rig in North Dakota that has a wall thickness of about 3/8" or maybe even a little more.

My question is this: I can see from the videos on youtube that mild steel will rust out, eventually leaving nothing. With this 3/8" well casing, how long would you expect a heat riser made of this material to last? I know you can't say exactly, but are we talking weeks, months or years?

Second question: I noticed on one of PPotties videos he seems to be using some pretty thin stainless with perlite insulation for the heat riser. How long would you expect this thin gauge stainless to last?

Finally, would you say that the heat riser gets hotter than the horizontal burn chamber?

Thanks for the input!

I have used 4" stainless steel exhaust tubing for my heat riser on two builds, my first build I used three inch and it worked well, after a full winters use I took it apart and found zero degradation.

And yes the up riser tube gets much hotter than the firebox, the temps in the riser tube I have been told can reach as high a 2000 degrees.

Not so in the firebox. I have no idea if your tube will hold up to those temps, my inclination from the very start after researching these was to go with stainless steel for the riser tube.
Everyone that uses mild steel wind up replacing them.

Answer 1 : In my opinion, even 3 mm gauge pipe heat riser will last for years.

Answer 2: I do not know, have no experience working with stainless steel.

Answer 3: Again, I do not know, I have to buy a thermometer to measure temperature values depending on the location of the fire box in relation to the riser tube.

i caught ppottys file on youtube where steel was used for the stainless steel part as i was just about to build it all in steel when i came across the file

https://www.youtube.com/watch?v=Cf6AnGOqLUc

so im glad that it was posted up on youtube