RELIABILITY-BASED RE-QUALIFICATION OF EXISTING OFFSHORE PLATFORMS

This paper describes the philosophy and principles that should be applied in developing procedures for re-qualifying existing platforms, for an extended service period, with particular view of crack growth, based on the results of in-service inspections, weld improvement, and possible increased inspection program. These principles have been applied to assess existing North Sea platforms. A probabilistic fracture mechanics model is applied toward this goal. Application of this methodology requires determination of largest safety levels, which are consistent with the safety regulations to comply with as well as the reliability method to be used. In this paper particular attention is paid to establish the target level.