The following documents, in whole or in part, are normatively referenced in ISO/TR 18491:2015 and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 15607, Specification and qualification of welding procedures for metallic materials ? General rules ISO 17662, Welding ? Calibration, verification and validation of equipment used for welding, including ancillary activities ISO/TR 17671 (all parts), Welding ? Recommendations for welding of metallic materials