Integrity Management of Ageing Offshore Structures: Technical Developments and Challenges

Abstract

The offshore industry in the North Sea and other parts of the world is a mature industry and a significant and ever-increasing proportion of the infrastructure is being operated beyond the original design life. This requires the implementation of a suitable integrity management system based on the use of codes, standards and guidance, which have been developed from a considerable body of research over many years, to enable the safe operation of ageing structures. During this time, the Health and Safety Executive (HSE) has led the commissioning of relevant research aimed at developing suitable guidance in support of its enforcement activities. This has covered a very wide range of relevant topics and the substantial body of results has been incorporated subsequently into offshore industry standards and guidance. Despite the considerable technical advances that have been made over the years in areas such as fatigue performance, static strength, inspection techniques / strategies and repair methods, significant technical challenges to the maintenance of the integrity of ageing structures remain. This is due to the uncertainties associated with complex analytical predictions and the condition of the structure, the full extent of which is not always known due to limitations in current inspection methods and practices. Furthermore, the economic aspects of continued operation present another important challenge. In addition to the detailed review of the extensive research programme funded by the UK Department of Energy and the Health and Safety Executive, the paper addresses the several uncertainties that are relevant to the safe management of ageing and life extension of offshore structures and the consequent challenges that characterise integrity management strategies.