As I continue building up my forge, I'm wondering how people set up the nozzle penetration on their gas forges. I've read where some people have the nozzle completely penetrate the insulation by a fraction of an inch, whereas others only stick halfway through the insulation and then form the remaining insulation as a continuation of the nozzle flare. How have you done it, and what was your experience?
The forge I'm building will use (2) 1" thick pieces of Kaowool for insulation, with rigidizer and IR coating. My burner will enter the cylindrical forge at about 45°, aimed at the soft firebrick floor (which I will also coat with IR goop). The body of the forge is a scrap propane tank, 12" diameter. If I stick the nozzle all the way through the insulation, it will hit the floor at 45° at a distance of about 7". I could pull the burner out of the forge an inch - so the nozzle only penetrates the outer layer of Kaowool, with the hole in the inner layer flared like the nozzle - but even with rigidizer I'm wondering if I'll end up eroding/blowing out a bunch of the insulation. What about the soft firebrick floor? I'm hoping that the jet impingement won't lead to significant erosion, but at least it will be easy to replace with something more robust if necessary.