Another problem with using a propane torch to fire something is uneven heating. The spots where the torch hits can get very hot, but other parts of the piece are considerably cooler. The thermo-shock between the hot and cool spots are very likely to lead to cracking as the clay goes through major changes when the chemically bound water in the clay body is released and when the quartz in the ware changes composition when heated.
If you are using the torch to heat a chamber with the ware inside (like a small kiln) so that the atmosphere and bricks are heated as well, that is an entirely different situation and may work.
As always, your situation may vary. Test, test, test.