As far as I know, propane with oxygen will burn at 2800 °C and steel will melt at ~1500 °C. Brass is even less.
What I am trying to do is a rocket nozzle.
Is there a way I can built this with steel or is it simply too hot? And for the burning temperature of propane, 2800 °C, is it the temperature IN the nozzle, OUT of it, or IN the combustion chamber?