Specifies requirements for the welding of steel structures made up of combinations of steel plate, sheet or sections, including hollow sections and built-up sections, or castings and forgings. It is limited to the welding of steel parent material with a specified minimum yield strength not exceeding 500 MPa. It does not apply to oxyacetylene, friction, thermoset or resistance welding processes or to the welding of pressure vessels or pressure piping.