Insulation for Steel Oven

[BobGPizza]

This is my first post, but I've been poking around on this site for a quiet a while now, and really appreciate all the good info I have found.

I'm in the process of building a 30" Naples style pizza oven for home use out of 11ga 316L Tig welded with Inconel 625. It will have a geodesic dome over top and I'm thinking ahead on insulation. The oven floor will be 1" castable refractory over 2" castable insulation. My question is whether to use ceramic blanket over the sides and top or whether to use the 2" castable insulation. I'm thinking it might heat up more evenly with the castable, thinking it should add some heat mass considering it's cured weight. I'd appreciate any comments or suggestions from anyone that has some experience with steel ovens. Thank you very much, Bob

[JRPizza]

Thanks for sharing this interesting design! I like to tack metal together, but you are obviously working on a higher plane. Are you just interested in cooking pizza or do you want to do some retained heat cooking? If yes, you probably want to do something that increases your thermal mass, which would mean using castable refractory on the dome first vs castable insulation. The 1" mass in the floor also might be on the minimal side to do much cooking without a live fire. You also might want to consider going a little thicker on the insulation as even with the 3" blanket I used I can feel the outside of my dome getting warm, and my metal door with 3" gets hot enough to burn my fingers if I am not careful.
The exterior dome, if it looks like the interior,

[UtahBeehiver]

Very nice, tig work on SS. We do not see a lot of steel ovens on this forum and when we do we do not get much feedback on how they work. One of the main issues will be that the SS has a very high K value (thermal conductive coefficient) although not as bad as carbon steel, ie 43 carbon steel, 16 SS, 1.4 firebrick. So the oven will need some way to keep the SS from sucking the BTUs away and some place to store the energy. It is a catch 22. Dense refractory will store then heat but the expansion rates between the SS and refractory are different which IMHO, will lead to cracking of the refractory shell. On the other hand, ceramic fiber blanket will adjust to the SS expansion better but will not provide the thermal mass that dense refractory will. I am going to leave it others to chime in on this.

[BobGPizza]

Thank you for the info. I plan on live fire cooking, pizza and artisan breeds, so I'm primarily concerned with temperatures being reasonably stable. I've thought of putting expansion joints in the cast insulation, and maybe even putting a 1" layer of the blanket between it and the dome to provide a little room for expansion. I'm trying to make it possible to disassemble it into manageable weights if I ever need to move it. It's all a compromise to keep the weight down.