Abstract
This paper presents the process and methodologies put in place by Total, a major operating company, to manage the structural integrity of its fixed steel offshore platforms located in 12 different affiliates. This paper presents the STIMS (Structural Integrity Management System) which has been put in place to address the integrity of fixed steel offshore platforms. A FUIMS (Floating Units Integrity Management System) is in place for many years to address the integrity of floating units. The STIMS allows in particular the operating company to cope with the recently published third edition of ISO 19900 which requires: "Models used in the analysis and the design/assessment verification of the offshore structure shall be maintained and kept up to date throughout all phases of the structure's life cycle. The operator shall be responsible for ensuring this."
After a description of the fleet of fixed platforms of the operating company (worldwide repartition, age, water depths…), the organization and process put in place between affiliates and Head Quarters, specifically dedicated to fixed steel platforms integrity, are presented. Then some specific methodologies are presented, in particular a new pragmatic approach to define Risk Based subsea inspection plans, which are essential to ensure structural integrity. First, a methodology for inspection prioritization by combining failure consequence, fatigue and inspections results is presented. This method has been implemented for a few decades and identifies the joints most critical to the structural integrity in order to inspect the relevant structural components for ensuring a lifetime extension of a jacket structure. Then, the definition of intervals between inspections is based on a new pragmatic simplified RBI process, called RBI-J. The outcome of the RBI-J analysis is the intermediate and major underwater inspection intervals of offshore structures. It is based on a semi-quantitative approach to estimate the global probability of failure of the platforms due to extreme storms or earthquake. It takes into account the results of the in-place and seismic analyses with some additional semi-quantitative parameters such as robustness, design life, inspection history, cathodic protection, and unprotected appurtenances. The consequences of failure are based on the risk matrix of the operating company, which allows also to estimate the global risk. In line with API RP 2 SIM this risk is then used to define underwater inspection intervals.
The paper concludes with some examples of application of the RBI-J methodology.
The RBI-J methodology is used on the vast majority of the fleet of fixed platforms of the operating company. Full probabilistic analyses are only used on a case by case basis (harsh environment, platforms in poor conditions…).
