ISO 11970:2016

Overview

ISO 11970:2016 - Specification and qualification of welding procedures for production welding of steel castings - defines how to qualify a Welding Procedure Specification (WPS) and documents the required tests and limits of validity for production welding of steel castings. The standard applies primarily to arc welding of steel castings, but its principles can be applied to other fusion welding processes by agreement between the contracting parties. It sets out requirements for preparing a preliminary WPS (pWPS), performing welding procedure qualification tests and recording results in a Welding Procedure Qualification Record (WPQR).

Key topics and technical requirements

• Scope of qualification: Defines the essential variables and the limits of validity for qualified procedures (material groupings, thickness ranges, welding process, position, joint type, filler metal, current type, heat input, preheat/interpass/post‑weld heat treatment).
• pWPS and WPQR: Preparation of a preliminary WPS and formal WPQR documentation for traceability and acceptance.
• Test piece and sample preparation: Shapes and dimensions for plate, tube and cavity samples (figures provided), including requirements for tack weld handling and angular tolerances.
• Examinations and tests:
  • Non‑destructive testing (NDT): magnetic particle inspection (MPI), liquid penetrant (LPI), ultrasonic (UT) and radiography as applicable.
  • Destructive testing: transverse tensile tests, macro‑examination, micro‑examination, hardness testing and impact testing (Charpy V) where required.
  • Additional purchaser‑specified tests: longitudinal tensile, bend tests, chemical analysis, ferrite in austenitic stainless steels, elongation and radiography.
• Welder qualification: Welding procedure tests qualify the welder within the appropriate range in accordance with ISO 9606‑1; additional welder qualification rules apply.
• Range and limits: Clause 8 details how qualification ranges apply to material, manufacturer, process specifics and common variables.

Practical applications - who uses ISO 11970

• Welding engineers and procedure writers creating WPS/pWPS for steel castings
• Foundries and manufacturers performing production welding or repair welding on cast components
• Quality managers and inspection bodies responsible for WPQR preparation and witness testing
• Purchasers and clients specifying acceptance criteria and additional tests for critical service or material conditions
• Certification bodies and auditors assessing compliance with welding procedure qualification requirements

Related standards

• ISO 15607 / ISO 15612 - General rules for specification and qualification of welding procedures
• ISO 9606‑1 - Welder qualification (steels)
• ISO 5817 - Quality levels for welding imperfections
• NDT and testing standards referenced: ISO 148‑1 (Charpy), ISO 4136 (tensile), ISO 4992 (UT), ISO 4993 (radiography), ISO 4986/4987 (MPI/LPI), ISO 6507‑1 (hardness)

ISO 11970 is essential for organizations that need robust, auditable welding procedure qualification for steel castings - ensuring repeatable quality, traceability and acceptance for production welding.