Gasket for firebox door

[Bricklayer]

My arch door is from an old wood furnace. It's pretty heavy duty, double walled made from 3/16 steel. Trouble I am having is how to seal it. I welded an angle iron frame that the door bolts to. This gives me a lip inside to insulate and firebrick up to. The door bolts on the outside of this frame. I'm sure it will get to hot to use high heat silicone. Can I use gasket cement then bolt it down. I know gasket cement can withstand 2000f but gets brittle. Or could I use pan gasket and sandwitch it in between and tighten bolts? My other dilemma is the actual door. I welded bolts to it. I put a piece of ceramic blanket on it. Seems to catch and tear and after a few times opening it there are gaps already. I was thinking of cutting the flange that is on the door frame down an inch and putting 2 squares of ceramic blanket. This way the flange closes to the blanket and not inside it. Thanks

[psparr]

Don't know about the door gasket, but I had the same problem with the insulation tearing from the wood.
I covered the insulation with some sheet metal from some metal ductwork. Held up all last year.

[Bricklayer]

I've got some asbestos board. My neighbour gave it to me. It looks like cement board but it's pretty dense. 3/8" thick. Could probley put a piece of that over the blanket.