Shielded Metal Arc Welding
Shielded Metal Arc Welding (SMAW), Submerged Arc Welding (SAW), Gas Tungsten Arc Welding (GTAW), and Gas Metal Arc Welding (GMAW), cause very small particles that are formed when the vaporised metal rapidly condenses in air, and are typically too small to be seen by the naked eye, but collectively, form a visible plume. These fumes can be harmful if inhaled through the nose and mouth of the welder. The content of the fumes may be either asphyxiating or toxic. The electric arc welding processes generate dust and particulate fumes, which when inhaled regularly over long periods can result in serious effects on the welder’s health. The fumes and dust generated during arc welding may be carried into the zone around the welder’s face by convection currents rising from the arc. Metallic vapors, mostly oxides, and silicates of metals react with atmospheric oxygen resulting in the formation of fine dust. Especially dangerous are the oxides of zinc, lead, cadmium, beryllium, and copper formed during welding copper, brass and bronze. Also during arc welding, the atmosphere surrounding the welder is contaminated with manganese compounds, nitrogen oxides, ozone, carbon monoxide, and fluorides. Some fluxes on melting give off oxides of manganese in dust form as well as hydrogen chlorides and fluorides. In carbon dioxide (CO2) welding, carbon monoxide may be produced by the decomposition of CO2 in the shielding gas or of carbonates in flux cored wire.