ABS reissued its “Guide for Building and Classing Floating Production Installations” (FPI) in April 2004, publication #82 to include specific guidance for spars and tension leg platforms (TLPs).

“By applying the evaluation techniques contained within the Guide, together with future class surveys, ABS offers clients like Chevron the most advanced approach to the evaluation of structural integrity and reduced operational risk,” said ABS Project Manager Dick Vukin.

Developed in response to emerging technological advances in spar and TLP design, that the update incorporates ABS’ extensive experience in classing these units while emphasizing the global performance issues and motion characteristics unique to these floating structures.

This Tahiti contract marks the industry’s fifteenth spar, with ABS having classed 14 of the units. ABS will class the Tahiti unit as an A1 Floating Offshore Installation (FOI). FOIs include spars, semisubmersibles and TLPs, in addition to ship-type process and storage facilities.

Classification will cover the Tahiti unit’s hull, mooring systems, topsides, power generation, platform layout and all marine, utility and safety systems, including life-saving equipment and fire-fighting appliances. The classification will not include the hydrocarbon production facilities.

ABS also will act on behalf of the U.S. Coast Guard and as a Certification Verification Agent (CVA) for the U.S. Minerals Management Service. CVA review and approval for Tahiti will include structural design, fabrication and installation.

Tahiti is planned for Green Canyon Blocks 640, 641 and 596. The oil major also operates the “Genesis” spar, installed in the Gulf of Mexico in 1998.

“In classing Tahiti and other FOIs using the newly updated Guide, ABS offers clients an effective approach to the life cycle evaluation and maintenance of the unit,” he adds.

While the FPI Guide addresses column-stabilized units and other types of floaters, key areas of emphasis in the latest edition include global performance requirements, load and environmental issues, stability parameters and structural strength criteria for spars and TLPs.

The Guide requires that owners of these units perform global performance analyses to fully address the comprehensive effects of environmental loads on an overall platform and its components, including the deck, hull, tendons, mooring system and risers, advises Vukin.

The new Guide requires that all emergency and safety systems, including life saving and abandonment equipment, are to be operational at parameters specified for storm survival and specific wind conditions. The detailed parameters define wind speed and list angle limits for varying operational scenarios.

Load issues addressed in the Guide include: environmental loads, hydrostatic pressures and buoyancy, gravity and inclination-induced loads, inertia loads, operational loads, mooring and riser loads, marine operation loads, vortex-induced vibration (VIV) loads during both transportation and operation and site-specific storm design levels.