The propulsion tailshafts fitted to submarines are potentially at risk from environmentally-assisted cracking in service due to the combination of a large number of rotating-bending stress cycles in conjunction with the possibility of exposure to seawater. Contact with seawater will cause corrosion pits to form which could act as fatigue initiators. To prevent this occurring, the exposed parts of the shaft are protected by an epoxy bandage. However, previous experience with older shafts has shown that the bandage may not entirely prevent ingress of seawater throughout the life of the shaft. In order to manage the risk of environmentally-assisted cracking, an Asset Integrity Management (AIM) strategy has been developed that defines a through-life inspection procedure intended to maintain shafts at their target level of operational safety. This paper describes the processes used to develop the AIM plan, establish user and system requirements, and select the optimum inspection technology for the application. The potential for transfer of this knowledge to future designs is also discussed.
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