As the Gulf of Mexico (GOM) fleet of Tension Leg Platforms (TLPs) ages, the need for more explicit Integrity Management (IM) and life extension guidance, particularly for the tendons, has grown. Recent industry efforts have developed Structural Integrity Management (SIM) guidance for fixed and floating systems, but tendon-specific guidance is less detailed. The Bureau of Safety and Environmental Enforcement commissioned the study described in this paper to develop this guidance including providing greater definition of IM and life extension processes for tendon systems, and describing an approach for demonstrating the reliability of tendon systems subjected to fatigue degradation.
Four primary objectives are addressed: 1) tendon IM, 2) tendon life extension, 3) tendon fatigue, and 4) tendon component post-service testing. These topics were addressed through the input of subject matter experts, interfacing with TLP operators, and developing analytical tools. The study looked at current industry practice for the design and management of tendon systems; how current SIM approaches can be applied to the unique features of TLP tendons; what are the critical features of tendons to be addressed as part of a life extension program; tendon fatigue factors of safety; how reliability approaches can be used to better define risks related to operating beyond the original service life; and how forensic testing of recovered tendon components can be used to gain a better understanding of tendon performance expectations.