Summary
- IACS (The International Association of Classification Societies) revised its welding Unified Requirements for marine/offshore structures.
- UR W28 Rev.3 aligns WPS qualification with ISO 15614-1 and AWS D1.1/D1.1M.
- The update clarifies high heat input welding and NDT waiting times by steel yield strength.
The International Association of Classification Societies (IACS) has published revisions to its welding rules for marine and offshore structures, updating Unified Requirements (UR) W11, W16, and W28. The stated goal is to align high heat input welding requirements across these URs, improve welding procedure qualification, and keep better consistency with international standards.
A main point is UR W28 Rev.3, which brings welding procedure qualification requirements closer to ISO 15614-1 and AWS D1.1/D1.1M. IACS also adds a clear definition of “high heat input welding” using energy input per unit length (kJ/cm), and updates the qualification range guidance (base metals, consumables, positions) plus provisions for post-weld heat treatment (PWHT).
The revision also introduces an optional approval route for high heat input welding procedures and adds Annex E in UR W28 for qualification tests using plates with approved high heat input grade notation. On inspection timing, UR W28 now spells out NDT delays: at least 48 hours for steels with 420–690 N/mm² yield strength, and at least 72 hours for 890–960 N/mm², unless PWHT is applied. UR W11 and W16 also add an optional manufacturing approval scheme for steels intended for high heat input welding (not mandatory), including thresholds mentioned for heat input above 50 kJ/cm (normal/higher strength) and 35 kJ/cm (QT steels).
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