Wet Welding Cavitation Erosion - Restoration of Weld Seams
Cavitation erosion of weld seams in rudders in an inherent problem that plagues vessels around the world. Prior to now, the only remedy available that was recognized by class societies was to perform a dry atmospheric weld to the affected areas in the dry dock or engage Subsea Global Solutions to perform a dry hyperbaric weld repair based on our existing weld procedures. As announced earlier this year, Subsea Global Solutions recently gained approval for more wet welding procedures. Groove weld procedures were approved meeting the Class A requirements of the American Welding Societies specification AWS D3.6M:3010 – Underwater Welding Code.
Utilizing the approved procedures, welder divers restored the affected weld seams on rudders on two vessels this past month thus allowing the vessels to remain in service. One vessel operating in the Cruise Industry and another vessel operating in the Container ship trade experienced considerable erosion of their weld seams in the rudder. With this excessive erosion, the class societies were forced to put a notation on the rudders and set time table for the execution of repairs in the dry dock. Since both vessels were far from their next scheduled dry docking period, Subsea Global Solutions was contacted to evaluate inwater options.
Repairs on both vessels were executed while they remained in service. By performing weld seam restoration with the wet welding process, the vessels could perform cargo operations at the same time that welder divers from Subsea Global Solutions completed the work efficiently without delaying any of the vessel’s schedules. Over sequential attendances, both repairs were completed to the satisfaction of the attending surveyor.
In both cases the erosion damage was considerable. Large sections of weld seam were eroded away in some areas with other smaller pockets of eroded weld seams were found in other locations on the rudder blades. The weld seams were restored with the parent metal using Hydroweld 3.2 mm mild steel electrodes. Once welding was completed, magnetic particle Inspections were performed to the restored areas and no linear indications were sighted.
Delivering unrivaled service starts with recognizing the need and adapting to fulfill the work completely, efficiently and cost effectively. Allowing a class recognized repair to be performed while these vessels remained in service, efficiently reduced the risk profile for class and the vessel owner.