Exposed steel in the arch

[berkshires]

I'm looking to put a layer of insulation held in place and protected with sheet metal in a few places in my arch. For example, on the door. This means the sheet metal will be directly exposed to the hottest part of the fire.

I was wondering - it seems quite hard to find stainless, especially thin cheap stainless, anywhere around me. Can I use plain steel, or will it get eaten up immediately?

Thanks!

Gabe

[wmick]

Stainless is better but mild steel will likely last a long time too.... (maybe go a little thicker with it?) Could also make it bolt-in or easily removable, in case you want to replace it...

Either way - you can expect it to warp like crazy when it gets hot for the first time.

[berkshires]

Yeah, some warping is no biggie. And I do plan to bolt it in using stainless bolts. Do you think 22 or 26 gauge would be thick enough to last for at least a few seasons? And zinc plated/galvanized seems to be cheap and plentiful - would that work?

[tcross]

I'm not real sure galvanized steel would be a great solution. I'm not 100% sure, but I think it omits gasses that are not good for you to inhale/be around. I have 3/16" plate steel sandwiching insulation for my arch door and it hasn't really warped much that I can notice. just my .02

[wmick]

Galvanizing (Zinc) melts at under 800 degrees F... so it will just burn off and be of no benefit to you... ... plain steel should be cheaper anyway... 22/26 ga seems awful thin to me, for this application...?? Not sure how long it will last?? I'd be going a little thicker if you can.

PS - just as a reference 3/16" (such as tcross used)... is exactly 10X thicker than 26 gauge....

[wiam]

On my Mason the door had 2" insulation held in place by a special rod/retainer set up. Not sheet metal protection. Worked great while I had it. My current oil fired has 5/16" stainless bolts with fender washers holding the insulation. Works fine.

[wmick]

On my Mason the door had 2" insulation held in place by a special rod/retainer set up. Not sheet metal protection. Worked great while I had it. My current oil fired has 5/16" stainless bolts with fender washers holding the insulation. Works fine.

This had crossed my mind, but I didn't want to confuse the issue with my ideas... I'd agree that if it isn't susceptible to too much mechanical damage... why not leave refractory material exposed, but supported??

[supersapper]

I have a friend that works at a gravel pit and he brought me a piece of stainless sand screen. Cut to size and used 2stainless bolts to secure and it has lasted 3 years so far. Rock wool 2 years, ceramic this year.

[TedA]

The problem with exposed steel is that they soon become red hot and are a hazard to your arms/elbows while fueling. The steel door on my arch came uninsulated and after burning my jacket and gloves a few times, I decided to put some insulation on the inside. First I used that fibrous ceramic blanket material. To hold it in place I drilled some hole through the door and bolted the ceramic blanket to the door with standard bolts and oversized flat washers. That lasted a year and then the bolts and washers were fried down to the point of being brittle and useless. I took that off and had a friend weld angle iron on three sides (inside) and so I could slide in a piece of insulation board. That worked well except that the angle iron was about 1 inch wide and the insulation board slightly less - about an 1/8 inch less. The insulation board slid around some so I wedged a couple of flat iron pieces (about 1/8 inch) in to keep the insulation board in place. However, the flat iron pieces turned red hot after a couple of fire-ups and were a serious hazard thereafter while fueling. Also, I tend to load my fire box very full and then squeeze the door shut. The insulation board doesn't hold up well when you are pushing it again chunks of wood. I'd like to go back to the ceramic blanket insulation but am at a loss on how to hold it in place. My last resort is to just stick with the insulation board and plan to replace it whenever it gets cracked or broken by the wood. Any other ideas on how to insulate the arch door?

[johnallin]

My last resort is to just stick with the insulation board and plan to replace it whenever it gets cracked or broken by the wood. Any other ideas on how to insulate the arch door?

I used ceramic blanket surrounded with stove gasket, sandwiched between the door and a stainless plate I had laying around. The plate is 1/4" and held in place with 1/4 -20 SS bolts. Four years ago, on my first attempt, I used some green ceramic board behind mild steel, but it eventually broke down and I had ceramic "dust?" flying around. Didn't think that was too good, so I went with the blanket and gasket to try and contain any particles.

So far after 2 seasons, other than some warping on the lower edge, it's holding up just fine. Hope this is helpful.

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[TedA]

Johnallin, thanks for the pictures. I like your sandwiche approach but wonder how long it will hold up. I suspect the bolts or nuts (whichever is on the fire side) will eventually disintegrate from prolonged exposure to extreme heat. If you got two years out of it w/o having them turn to dust, my hats off to you. Did you use some special bolts that can take the heat? Also your inside part of the sandwich appears to be metal. Tell me that won't get red hot after an hour or two of steady cooking. Then like my small flat iron wedge pieces, it becomes a hazard while fueling. Sounds like there is no easy solution.

[mol1jb]

On the 2x6 I made last year I welded nuts to the inside of the door and just used bolts through the insulation blanket to keep it attached the door. The bolts were 1/2 inch grade 8 and held up great. I have heard of others using grade 8 bolts with good success

[johnallin]

Johnallin, thanks for the pictures. Did you use some special bolts that can take the heat? Also your inside part of the sandwich appears to be metal. Tell me that won't get red hot after an hour or two of steady cooking. Then like my small flat iron wedge pieces, it becomes a hazard while fueling. Sounds like there is no easy solution.

The bolts are stainless steel along with the inside piece of metal. So far, after two seasons, so good. It does get hot, but no hotter than the cast iron door alone.

[TedA]

OK, johnallin is on to something here. After reading his response, it seems that I made several mistakes. One was my bolts through the door were too small. Second they were not stainless steel. Third my wedge pieces were barely 1/8 inch and were normal ferrous steel, not stainless. After a couple of hours of cooking, my thin wedge pieces were bright cherry red (i.e. super hot). Johnallin used stainless bolts and his inside plate is 1/4 inch stainless - which being thicker and stainless - heats up more slowly.

[Sugarbush Ridge]

I use some expanded metal. Yes, only last one or two years but holds and protects blanket.

[smokeyamber]

I would second using just plain steel, and the stainless bolts, just did this on my setup, and yes the sheetmetal does get a nice cherry red, but should last several seasons. My rig throws enough heat that loading is done from the side so I am never too close to the red hot metal.