The use of inspection and monitoring reliability information in criticality and defect assessments of ship and offshore structures

This paper describes the use of inspection reliability information in fitness-for-service and criticality assessments for ship and offshore structures. Assessments of components that have never been inspected should assume a defect distribution from manufacturing quality assurance reports taking into account any propagation of damage that might have occurred. By understanding how to incorporate Probability of Detection (POD) and Probability of Sizing (POS) information with associated confidence measures into damage modelling, operators can appreciate the benefit of conducting inspections and the resulting implications for quantitative risk assessments particularly where no defects are found. The paper illustrates the use of POD and confidence levels for predicting remaining life due to corrosion and fatigue and also how to incorporate sizing statistical performance characteristics of the inspection system into remaining life assessments. In addition, the paper addresses the emerging trend towards monitoring with inspection and how operators and designers can benefit from future trends in structural health monitoring.