Assessment of Residual Life of Existing Fixed Offshore Platforms

Life extension and platform re-use are in demand now, which creates a need for evaluation methods able to ascertain the residual life of an existing platform, to be eventually operated in a new installation site. A system approach, used by operators in different offshore areas, is presented in this paper. Indeed, for existing platforms, it is permissible to have limited individual component failures, provided the reserve strength against overall system failure remains acceptable. This system was used to determine the life expectancy of a platform used in the Gulf of Mexico for ten years, which was to be accordingly modified and installed on a new site off Congo. The analysis showed that a service life of ten years was feasible without need for strengthening. Lessons learned from the specific analysis are outlined in the conclusion, providing guidance for the definition of acceptable component failures depending on the accepted risk level.