Gymbo1

I am building a Propane tank gas forge and i am using T burners. I am going to be using 2 inches of ceramic wool and covering that in refractory. I am having trouble finding information on how far the pipe bracket for the burner should go into the forge. I am thinking it should just go to cover the wool and use a form for the refractory is this the way I should do it? Also I am worrying about the refractory falling from the top is this a risk or should it stay in place after hardened? Thanks.