Welcome to BF.
I'm not sure of your setup,but it sounds a bit like a bomb to me.The air needs to be mixed with the gas.It is mixed either by venturi in an atmospheric forge,or under pressure in a blown forge.All burners should be burning the same mix.If there is a hot or cold spot,adjust that burner so the heat is even.Let the forge come up to heat for a while before putting in the metal.The idea is for the chamber to be hot,not just the flame heating up the steel.Adjust the temperature of the forge chamber by controlling the gas flow with a needle valve,and/or reducing/increasing the air flow with a restrictor gate(like a dust collector gate).Run some searches on forge burners and you will see several ways to make burners.If you already have a commercial four burner forge,you are all set up to do most anything.Get it hooked up right,though.
