Passenger ships can operate in extreme and harsh conditions and are designed for a certain life span. Lloyd’s Register is currently investing in monitoring technology and methods that will lower the costs of Integrity management of ageing ship structures. There are differing requirements from a statutory and operator point of view. This is a complex and difficult arena with potentially significant benefits where TRUSS will invest further research.
Lloyd’s Register has operated a long term acoustic emission and strain based monitoring system on a semi-submersible offshore asset in the North sea to identify and quantify any fatigue related cracking in nodal joints. It has also operated long term vibration and strain based monitoring system on a class of cruise ships to assess the loading and monitor the effects of structural changes which has been used to support the recommendations for the structural integrity management of these vessels. Both sets of data are also correlated environmental date sets including wave height, wind speed and direction.
The long term data sets already gathered are unique and valuable and representative selected sets will be made available to the ESR. Furthermore global FEA models of vessel, fatigue test characteristics of materials with a range of instrumentation for crack detection and monitoring will be available to the ESR on a similar selective representative data set basis. The monitoring and test programmes undertaken can be viewed as specific examples of integrity monitoring and assessment. The methodology will be extended to improve the prediction and identification of structural issues which threaten the integrity of the vessel from both the statutory and operator points of view.