Alpha and some gamma radiation from thorium. 8.15.2.2 Gas Welding Gas welding is the coalescence of metals by heating with a gas flame, with or without filler metal and use of pressure. Types of gas welding include oxyacetylene, oxyhydrogen, oxygen-propane, natural gas, and methylacetylene propadiene. Resistance Welding Resistance welding is the coalescence of metals produced by heat generated by the resistance of the work to electric current. Filler metals and fluxes and metals are not used.
Resistance welding includes spot, seam, projection, flash, and upset welding.
The filler metal distributes itself among the closely fitted surfaces of the joint by capillary action. Brazing and soldering in common use include torch, induction, dip, resistance, and soldering iron processes. Cadmium and lead are commonly used in solders. Gases from fluxes, commonly fluorides and other halides. Burns from contacting hot irons.