Field Implementation of RBI for Jacket Structures

Abstract

After a brief outline of the simplified and generic approach to reliability- and risk-based inspection planning, focus is set on a recent application of the methodology for the planning of in-service NDT inspections of fixed offshore steel jacket structures in the Danish part of the North Sea. The study includes a sensitivity analysis performed for the identification of relevant generic parameters such as the bending to membrane stress ratio, the design fatigue life, and the material thickness. Based on the results of the sensitivity analysis, a significant number of inspection plans were computed for fixed generic parameters (predefined generic plans) and a database named iPlan was developed from which inspection plans may be obtained by interpolation between the predefined generic plans. The iPlan database facilitates the straightforward production of large numbers of inspection plans for structural details subject to fatigue deterioration, as illustrated by an example in the paper.