BC Ferries was made aware of cracking on the spirit class rudder trunk, port side, during a dive inspection. The crack was 20mm in length and located on the trunk side of a reinforced groove weld joining a shell plate to the rudder trunk section. BC Ferries was granted temporary approval from ABS for an underwater repair of the crack until the scheduled dry dock of the ferry where the crack region was to be re-excavated and repaired on shore.
BMT was contracted to perform a review of documentation and prepare a repair welding procedure qualified to ABS standards complete with information on preheat, interpass, postweld heat treatment conditions, recommendations of preferred heating methods, electrode size, electrode type, electrode storage requirements, pass and layer sequencing, welding parameters, heat input values, mechanical properties and chemistry of base materials, and NDE requirements during welding operations.
BMT prepared the initial procedures with the repair welding witnessed by BMT as the third party to ensure compliance of the procedure and to address issues as they arose. After completion of the welding repair, a documentation update was performed to ensure the welding procedure reflects the changes made in the field. The final welding procedure was accompanied by a report for use in future crack repairs of this nature.
In a short time frame, BMT was able to research the documentation provided by BC Ferries, prepare a repair welding procedure and provide ABS with documentation of previously approved procedures that satisfied for approval. Acceptance was granted from ABS in time to perform the repair work during the scheduled dry dock, eliminating extra down time for the ferry.