I have got a 12” piece of carbon steel pipe that’s about 3 foot long I also have an entire roll full box of 2” insuwool they were both free from work I am wanting to build a 2 burner forge is the pipe going to be too big to use am I going to waste a lot of propane. I realize I will have to shorten the pipe which I am prepared to do. I just need to know how long of a piece I should cut off it