propane forge insulation

[KPeacock]

My kaowool arrived yesterday, so I am ready to go with the propane forge. I'm heading out this afternoon to purchase the castable refractory and firebricks. I believe the gentleman resommended KS4. I'll simply trust that they know more about this part than I do.

 

When I apply this castable refractory, how thick should I apply it? I realize that this is relative and there is no one righ answer, but am I looking at a simple application just to coat the fibers, or do I want it 1/2" thick? My forge body is 8" ductile iron pipe with 1/2" wall thickness. I have two, 1" layers of kaowool. This leaves me only about 180-190cubic inches of chamber volume. I had planned on using hard firebrick for the bottom of the forge, but after seeing how small my chamber volume is, I think I'll run 1" of kaowool on the bottom with the firebrick on top of that. I don't think I'd have room for a billet with the firebrick sitting atop both layer of kaowool.

 

Any thoughts, tips, or tricks for this stage of the construction. Id rather do this right once than have to redo it becasue I overlooked something simple.

 

Thanks,

 

Kris

[cdent]

I think the castable refractory and the kaowool do similar jobs, just different applications. It seems insulating 'wool' is sealed with refractory cements that are usually applied thinner than the castable products.

 

I think if you have 7" of inside diameter, you may run out of room real quick with two layers of koawool around most of the interior plus the castable. I have a 7" body with thinner wall. One inch of inswool and about a quarter inch of satanite/itc 100 leave only about a 4in. diameter chamber. My set up doesn't use a fire brick. My set up is cool to the touch on the outside of the forge body.

 

Sorry if I read it wrong, happy Thanksgiving, Craig

[KPeacock]

You read it properly. And yes, I'm now down to a 4" diameter chamber. this is fine for what I plan to do, but I don't want it much smaller than this. I'm also wondering if I would be batter off having only 1" of insulation this increasing the chamber size. about a 6" diameter opening. This pute me at an interior volume of 420 cubic inches...which seems high to me, but I'm no expert in the field.

 

It is my undrstanding that th kaowool is there for its insulative properties. the castable refractory is there to keep the kaowool from degrading and becoming airborn. Also, I've heard that flux will destroy the kaowool, so the castable works as a barrier to prevent the flux from coming in contact with the kaowool.

 

I could be misinformed on this point, but that's my understanding.

[Doug Lester]

The castable refractory that you got will protect the ceramic fiber blanket from heat of the forge, but more importantly, it will protect your lungs from inhailing the heated fibers which can really mess you up. The other thing that the refractory will do is work as a heat sink and soak up the heat and reflect it back. I put about a 1/2" coating on the inside of my forge. I'd stick with 2 1" layers of the insulation. I think that it will make your forge more effecient.

 

Doug Lester

[Tom Demitras]

Another option that should let you run a little thinner insulation is that IR reflective you put over the castable. ITC 100 I think it is. Its a bit expensive but man is it effective. I went from being able to forge, to accidentally melting some steel that I was soaking while working on something else. I have some around here somewhere...I think.

[Matt Bower]

I suggest you go with maximum insulation and minimum castable, consistent with: (1) the interior size of the forge you want (could you get a bigger shell?); (2) protecting the wool from mechanical damage; (3) providing a flux-resistant floor; and (4) sealing in the wool. The ITC 100 is a good idea.