OT, looking for high temp expanding foam (sealant)

This is a little different. Our company has just installed a second hand powder paint line. The cure oven was cut-up into 3 sections to make them small enough to transport over the road. Now, after pulling the sections back together to make a whole oven again, we have some gaps where the disassembly "experts" torched things apart. I'm wondering if any of you know of a product (other than high temp silicone caulk) that we could seal up these gaps. Widest gap is 3/8", and get narrower from there. It would be nice to find some kind of high temp. expanding foam. The max. oven temp. is 460° F. Any suggestions would be greatly appreciated.