Merging ASME and API Design Methods for Subsea Equipment Up To 25000 PSI Working Pressure

摘要

A current challenge in the oil industry is the design of subsea equipment for pressures more than 15000 psi. Current standard, American Petroleum Institute, Specification, 17D (API 17D) for designing subsea equipment is limited to 15000 psi working pressure. One of the key recommendations of API TR PER15K (draft) is the utilization of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Codes (BPVC) for designing pressure vessels for pressures above 15000 psi. This paper proposes a design methodology combining the relevant API and ASME design codes for the design of subsea equipment for pressures more than 15000 psi.rnSpecific guidance is provided in this paper to safely utilize the ASME design methods with API materials. These approaches allow for the increase of ASME design test pressures to match API while satisfying ASME and API design allowable limits. Methods and guidance are provided for the use of stress classification, stress linearization, protection against general plastic collapse, local collapse, buckling and cyclic loading. Recommendations are made for Load Resistance Design Factors to accommodate the difference in hydrostatic test pressure between ASME and API. Additionally, approaches using both traditional stress-based fatigue analyses methods and fracture mechanics theory are compared. The design of closure bolting conforming to API requirements is integrated with the ASME methods, along with the recommendation of non-destructive examination (NDE) requirements to align with the recommended stress and fatigue design factors.rnAn example design evaluation of a pressure containing API 6A, 4 in. 20 ksi type 6BX flange is presented for a design pressure of 20000 psi with bolt preload as recommended in API 17D. The results show the existing API methods are adequate up to 25000 psi and the design verification methods meet the recommendations of API TR PER15K.