Evaluation of reliability and safety for an underwater dry maintenance cabin

Effectiveness of an underwater dry maintenance cabin (UDMC) is mainly determined by its reliability, availability and safety. In this paper, the reliability and safety of a UDMS is evaluated qualitatively and quantitatively via fault tree analysis (FTA). According to the composition, mission characteristic and operational condition of the UDMC, three kinds of typical failure patterns are identified. All ultimate causes, or combination of causes that are responsible for or contribute to the top events, are recognized via FTA. Then, based on minimum cut sets, probability of system failure is calculated by numerical simulations which show that UDMC is of high reliability and safety. Moreover, with the aid of theory of the critical importance, the weak links of the system, which are required in making an effective preventative maintenance strategy, are identified. Finally, suggestions to improve the reliability and safety of the UDMC are proposed.