I've burned 5" thick plate with oxy-propane on the mechanized burning table in my shop. However, if your main use is heating, you might be better off using acetylene. Propane uses a lot more oxygen for the same heat output due to the difference in the chemical chain of propane vs acetylene. For my burning table it doesn't really make any difference since the bulk of the use is oxygen anyway, but it does make a big difference for heating. Also, gas welding doesn't go nearly so well with propane as it does with acetylene.