Filler-rod. A rod or wire used to supply additional metal to the weld.
Fillet Weld. A weld made in a corner.
Flame Propagation. The rate at which a flame will travel.
Flash Back. The burning back of the gases to the mixing chamber or possibly farther.
Flux. Chemical powder used to dissolve the oxides and clean the metal when welding.
Gas. Erroneously applied to acetylene gas alone. Both oxygen and acetylene are in the form of gas.
Gauge. An instrument for measuring pressures of gases.
Generator. A device for manufacturing gas. Usually specified as acetylene generator or oxygen generator.
Grain. The arrangement of the molecules or crystals which make up a metal.
Horizontal Welding. Welding in a level position.