Actually, IIRC "MAPP" means something like methyl acetylene, propadiene
stabilized. Machinery mfg I once worked for was required by insurance
co. to change over from using bulk acetylene bottles (where the
acetylene is dissolved in carbon disulfide, and such bottles get
explosive with little temp elevation) to bulk MAPP bottles. For
burning/welding steel. (In same vein, USN will not allow bulk acetylene
bottles to be stored within any space on ship; all are stored out in the
weather.)

The portable torch I have uses oxygen in refillable, MAPP in
disposables. There also, you can't tell the difference between MAPP and
acetylene for heating up steel for burning.

Bottom line: MAPP removes/reduces safety probs for really serious
torches. Maybe this carries over to air/fuel-gas torches?

Anyone knowledgeable about relative hazards of heating propane/MAPP
bottles? Risk-management rules. :')

John