So I’ve had this ?heat treating? Oven for 20 years. PO had piped it directly from his inside NG line. I guess it worked but I needed to use on LP. The 18 orifices were almost 5/16”
I couldn’t get any heat or good flame. So time to make a more appropriate LP orifice(s).
18 brass orifices, 5/16-18 and #14 drill, added 2 flats (quick and dirty) for 1/4” wrench.
Size F drill to clean up and tap.
Easily went up to 1400 deg F. I probably could get a bit more out of it fiddling with a mixture, but anything above the tempering temperature is fine for me.