ISO 15614-1:2004 specifies how a preliminary welding procedure specification is qualified by welding procedure tests. It defines the conditions for the execution of welding procedure tests and the range of qualification for welding procedures for all practical welding operations within a range of variables. Additional tests may be required by application standards. ISO 15614-1:2004 applies to the arc and gas welding of steels in all product forms and the arc welding of nickel and nickel alloys in all product forms. Arc and gas welding are covered by the following processes: manual metal arc welding (metal-arc welding with covered electrode); self-shielded tubular-cored arc welding; submerged arc welding; metal inert gas welding, MIG welding; metal active gas welding, MAG welding; tubular-cored metal arc welding with active gas shield; tubular-cored metal arc welding with inert gas shield; tungsten inert gas arc welding; TIG welding; plasma arc welding; oxy-acetylene welding. The principles of ISO 15614-1:2004 may be applied to other fusion welding processes.