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The role of the API Committee on Standardization of Offshore Structures is described. A brief history ie provided, committee organization outlined, and the range of reeponsibilities described. The method whereby standards are developed is discussed. Current and future anticipated activities are described. The range of standards developed by the committee is shown, and research activities are outlined. INTRODUCTION The American Petroleum Institute (API) is a trade association representing over 200 companies in all aspects of the oil and gas industry, including exploration, production, transportation, refining and marketing. The API was incorporated in 1919. The objectives of the Institute, as stated in its charter, are to: afford a means of cooperation with the government in all matters of national concern; foster foreign and domestic trade in American petroleum products; promote the interest of the petroleum industry in all its branches; and promote the mutual improvement of the members and the study of the arts and sciences connected with the petroleum industry.1 Since its founding, API activities have significantly expanded and have become increasingly international in nature. The API Production Department was formed in 1928 with a number of objectives, including: to develop and maintain specifications and recommendations for the manufacture, care and use of equipment and materials used in the exploration, drilling and production of oil and gas; and to establish and maintain an API monogram license program with quality requirements to ensure manufacturer who apply the API monogram to their products can manufacture to the applicable API specification consistently. The current organization of the API Production Department is shown on Figure 1. The Executive Committee on Standardization of Oilfield Equipment and Materials, among other duties, is responsible for the development of standards, to include specifications, recommended practices and bulletins. The Committee on Standardization of Offshore Structure ("Committee 2") is specifically charged with developing standards for the design and construction of offshore platforms, including standards for equipment packaging and arrangement. This paper will discuss the role of the API Committee on Standardization of Offshore Structures, including a brief history, current activities, published standards and envisioned future activities. HISTORY OF THE API OFFSHORE STANDARDIZATION EFFORT API activity in the field of offshore structures was initiated with an organizational meeting held at the Rice Hotel in Houston, Texas, on November 29, 1966. This was an informal gathering to determine the interest of the industry in developing standards for offshore structures. In addition to the API?s traditional purpose of "standardization" the expressed intent at the time was to provide guideline to "keep the uniformed out Of trouble" and to serve as the basis for future regulation. This meeting resulted in the formation of the API "Committee on Standardization of Offshore Structures." After over 20 years, it appears that these goals have largely been met. The API offshore standards are widely used throughout the world, and API RP 2A is referenced as a requirement in current U.S. Minerals Management Service (MMS) Regulations.

The Harmony and Heritage platforms are planned by Exxon Company, U.S.A., for installation planned by Exxon Company, U.S.A., for installation offshore California, in 1200 feet (366 m) and 1075 feet (328 m) of water, respectively. The design criteria and analysis procedures are an extension of the technology used for the 850-foot (259 m) water depth Hondo platform, about ten years ago. Each of various in-place (environmental) and installation loadings are discussed, and their relative impacts on jacket weight are evaluated. Introduction Exxon Company, U.S.A.'s Hondo platform was installed in the Santa Ynez Unit in the Santa Barbara Channel in 1976. The design and construction procedures of this 850-foot (259 m) water depth platform (which are described in References 1 and 2) have evolved to meet the additional challenges presented by the Harmony and Heritage platforms, the next developments for the Santa Ynez Unit. As shown in Figure 1, the Harmony platform will be located about 3 miles (4.8 km) west of the Hondo platform, and the Heritage platform will be located about 7 (11.3 km) miles west of Harmony. Pipelines are planned to extend from Heritage to Harmony, to Hondo, to a terminal. Like Hondo, both platforms were designed by Exxon Company, U.S.A., with extensive support by its research affiliate, Exxon Production Research Company. Designs for a one-and two-piece option and for a Far East and West Coast jacket assembly are essentially complete. The anticipated schedule for the platform jacket design and construction is shown in Figure 2. To capture economies of scale, design and fabrication of the Heritage platform is planned to be simultaneous with that for Harmony, and water phase construction will be sequential. phase construction will be sequential. PHYSICAL FEATURES PHYSICAL FEATURES As shown in Figure 3, the Harmony and the Heritage platforms are similar to the Hondo platform. They are all 8-legged, pile founded platform. They are all 8-legged, pile founded structures for the support of drilling rigs, production equipment, and personnel quarters. production equipment, and personnel quarters. The size of the new platforms prohibits the use of any existing fabrication yards on the U.S. West Coast. Also, no existing barge is capable of carrying either jacket as a single unit across the Pacific. Thus, to encourage competitive bidding and launch barge development, both one-piece and two-piece (like Hondo) jackets were designed and offered to potential fabricators. potential fabricators. The deck structures on Harmony and Heritage are essentially identical. They are three-level modular decks, atop a module support frame. The deck plan is 180 feet by 145 feet (55 m by 44 m) with a total area of about 78,000 square feet (7300 m2). Two drill rigs and 60 well conductors are planned for each platform. The total topside weights above the module support frame is about 40,000 kips (mass 18,100 Mg) for each platform.

A parametric model of the GB260 tower, relating global tower responses to all critical metocean variables, was calibrated to the full 3-D time domain simulation methods used in the final design. All historically important metocean event in the GB260 area were simulated, singly and in combination, with the model to create a extensive database of tower shear and moment responses. The metocean inputs were developed from industry-funded data sources for hurricanes (GUMSHOE), winter storms (WINX) and detached Loop-Current eddies (CASE). Sets of specific metocean events producing 100-year return period responses were identified from the response database and used as the basis for two independent design metocean events : hurricane dominant and Loop-Current eddy dominant. The methodology proved very robust; sets of metocean events which produced the 100-year response were essentially the same for shear and moment responses at tower levels simulated in the model, and for two tower designs of differing cross-section dimensions and number of wells. The response database was further analyzed to define directional distributions of extreme response for potential use in the design process. While the underlying statistical methods used are not new, their application to the design of the compliant tower subject to storms and Loop-Current eddies is new. The analyses allow the operator to achieve risk management objectives by explicitly accounting for tower response characteristics and possible interactions between severe storms and Loop-Current eddies. Introduction Consistent metocean design criteria for a compliant tower in the Gulf of Mexico were developed using probabilistic methods by associating hindcast hurricane, winter storm and Loop-Current eddy events with modeled tower responses. The methodology, summarized in Figure 1, accounts rigorously for all possible environments that are known to affect the site. There are four separate steps:construction of a simplified tower response model;cataloging of tower responses that could occur over the available storm and Loop-Current eddy histories;statistical analysis of responses to define 100-year values at each level of the tower;selection of metocean environments that produce design level responses. The simplified tower-response model is based on time-domain simulations of the full tower model conducted by McDermott Engineering. For the simplified model, the responses are the peak (in 1-hr) forces and moments at each tower level. These responses were correlated with metocean inputs to establish response estimates for arbitrary sea-state, wind, storm current, and Loop-Current eddy combinations. Once validated, the simplified model was used to compute thousands of possible responses based on the metocean conditions derived from the GUMSHOE (hurricanes), WINX (winter storms) and CASE (Loop-Current eddy) data bases. For a specific set of Loop-Current eddy states, conditioned-responses were compiled for all of the storm wind and wave data. The resulting tower-response catalog provided the basis for selecting design environments.

Comparisons are made between theoretical and measured resonant frequencies for three representative hydrofoil configurations (inverted pi, vee and inverted tee), with variable end conditions and depth of submergence in water. Theoretical calculations were based on influence coefficients, accounting for the "apparent mass" effect of the water. Agreement on frequencies through the first six to eight modes of vibration for all configurations is generally excellent, being well within 10 percent in most instances and in no case greater than 1 8.1 percent. Agreement on mode shapes is also generally good.