Structural Reliability & Integrity
Technical Bulletin 2011

This section of the Technical Bulletin includes five papers. Two of them deal with ice issues in relation to Arctic navigation, the three others are devoted to structural integrity of offshore units (FPSO and Offshore wind turbine farms)

ICE ISSUES IN ARCTIC NAVIGATION

The paper from Alexey Dudal and coll. explains why new engineering and class tools are needed to face existing demands for large tonnage ice-going ships in Arctic seas. The basic design appraisal of new types and larger tonnage oil tankers and LNG carriers requires new approaches and so new tools to predict ice load actions on vessel hull. The paper gives some insights about the software developed by Bureau Veritas in cooperation with STMU for direct analysis of hull structural strength under ice loading. It includes a description of the theoretical models and of the software. The results of an extensive validation on a fleet of aged ships are presented, as well as examples illustrating the application of the software.

In the second paper, Philippe Cambos and Olivier Cartier present the general context of the development of Arctic gas projects. They give the environmental context and the ship design rules developed by Bureau Veritas with a special emphasis on the LNG carrier case. A particular study of a membrane LNG carrier is detailed with the acceptance criteria definition and the results obtained showing that the membrane technique is perfectly adapted for the exploitation of the Arctic gas.

STRUCTURAL INTEGRITY OF OFFSHORE UNITS

The two first papers deal with FPSOs. Due to copyright issues, they cannot be included in the Technical Bulletin: only abstracts of the papers are given. The paper from Biasotto and coll. highlights best practices and procedures applied to structural integrity management of floating offshore installations, including not only technical aspects, but also integrity management review process, data and communication management. The paper from Goyet and coll. presents a probabilistic system approach for Risk Based Inspection of FPSOs. The approach is based on a hierarchical model of the hull and uses Bayesian Probabilistic Networks to propagate failure from component to system level. The system approach makes risk analysis more tractable because consequence analysis, which includes direct and indirect consequences of damages to the constituents of the system, may be developed in an exhaustive and systematic way. An example is given.

The third paper deals with the development of a decision support system for the online maintenance of an offshore floating wind turbine farm. This system is expected to be the backbone of the future Condition Monitoring Centres, which will remotely monitor the farms. The automated Decision Making module will take into account the specific issues of such a farm, in particular the fact it consists of many identical units. The use cases are investigated and the logics are explained with the necessary level of abstraction and generality, to accommodate future technological evolutions of offshore wind turbine sensors, NDT measurements and blade repairs.

CONTENTS