MAPP

MAPP gas is liquefied petroleum gas (LPG) mixed with methylacetylene-propadiene. MAPP is the tradename for a product of the Dow Chemical Company.

The gas is used for welding due to its high combustion temperature of 2927 °C (5301 °F) in oxygen.Although acetylene has a higher welding temperature (3160 °C, 5720 °F), MAPP has the advantage that it requires neither dilution nor special container fillers during transport, allowing a greater volume of welding gas to be transported at the same given weight.Also, MAPP is advantageously used in underwater welding, which requires high gas pressures (under such pressures acetylene polymerizes explosively, making it dangerous to use).

The biggest disadvantage of MAPP gas is cost; it is between two and four times as expensive as propane (depending on quantity, supplier, and bottle size). While nine kilogram propane cylinders are common, the largest MAPP cylinder available in Australia is three kilograms. Additionally, MAPP gas torches often cost more than propane torches, around 3 times as much.