How To Vent An Industrial Gas Oven

[nilcram]

I am in the process of having a large industrial oven installed. It is gas fired, and it has a max. temperature of 1200F. My contractor is struggling to find a code accepted way to properly vent this oven. The exhaust blower housing is designed for 8" flu pipe, but my contractor is not comfortable with that (even though this is OEM equipment).

I am thinking a simple double wall flue pipe rated for 1200F. Am I missing something here ?? I am not well versed in oven, furnace, and boiler installations.

Thanks in advance.
Mike