Simplified and Generic Risk Based Inspection Planning

Authors

Michael H. Faber, Svend E. Engelund, John D. Sorensen and Allan Bloch

Abstract

Practically applicable approaches to Risk Based Inspection of offshore steel structures are suggested. The approaches greatly simplify the practical aspects of identifying inspection plans complying both with specific requirements to the maximum acceptable annual probability of structural collapse and member failure and at the same time minimizing overall service life costs. The suggested approaches facilitates a generic representation of the fatigue sensitive details in terms of characteristics such as the Fatigue Design Factor, joint type, welding quality and Reserve Strength Ratio given fatigue failure. Characteristics commonly used in the fatigue design of offshore steel structures. Given information regarding the inspection reliability, the relative costs of inspections, costs of repairs and costs of failure together with acceptance criteria for the maximum acceptable annual failure probability, inspection plans may be pre-fabricated. The pre-fabricated generic inspection plans may be used in the design phases as a design tool to evaluate the effect of specific detailing on the requirements to future inspections and service life costs. Considering existing structures the generic inspection plans may readily serve as a maintenance tool for the planning of future inspections. Furthermore the generic inspection plans may also serve as a requalification tool support for assessing the impact on requirements to future inspections and residual service life costs as a consequence of increased loading, structural damages and strengthening. The generic inspection plans provide a format for inspection planning which appears adequate for codification purposes in connection with inspection planning of structures.

Published in/by

Proceedings OMAE2000, 19th Conference on Offshore Mechanics and Arctic Engineering, New Orleans, Louisiana, USA, February 14-17, 2000.