A gas such as acetylene, natural gas, hydrogen, propane, stabilized methyl aoetylene propadiene, and otherfuels normally used with oxygen in one of the oxyfuel processes and for heating.
To be suitable for welding operations, a fuel gas must have the following characteristics when combined with oxygen: (1) high flame temperature, (2) high rate of flame propagation, (3) adequate heat content, (4) minimum chemical reaction of the flame with the base and filler metals.
Among commercially available fuel gases for welding, only acetylene meets all these requirements. Other fuel gases, such as methyl-acetylene propadiene products (MPS), propylene, propane, natural gas, hydrogen, and proprietary gases based on these, offer sufficiently high flame temperature, but exhibit lower flame propagation rates. When oxygen-to-fuel gas ratios are high enough to produce usable heat transfer rates, the flames produced by these gases are excessively oxidizing. However, methylacetylene propadiene and hydrogen are sometimes used for oxyfuel gas welding of low-melting metals.
Such gases as methylacetylene propadiene products (MPS), propylene, propane, natural gas, and proprietary gases based on these are used for oxyfuel gas cutting, torch brazing, torch soldering, and other operations where demands on the flame characteristics and heat transfer rates are not the same as those for welding. See OXYACETYLENE WELDING and OXYFUEL GAS CU’ITING.