I'm designing a pre-heat oven for tower legs (ASTM A572). It will be about 4' X 5' X 32' long (640 cu. ft). (insulated steel box) I want to bring 2 legs 8" dia. X 30' long up to near 300 degrees F in 1 hour soak time. Need some help calculating the BTU input required and the temp setting to accomplish the temperature rise in the available soak time, please. Any guidance would be greatly appreciated. Have a good source for burners and planning on about 4-5 burners spaced down the box.