"Demand for LPG FPSOs is being driven by environmental concerns that have placed severe restrictions on the traditional method of flaring gas associated with production," says ABS Vice President, Offshore Project Development, William J. Sember. "By capturing these gases not only does the environment benefit, but also with the demand for gas forecast to double over the next decade, industry and consumers will benefit from this new technology."
The SANHA will include LPG storage tanks and LPG production plants such as gas separators, gas refrigerators and boil-off gas reliquefaction units on the upper deck or topsides.
Sember says ABS is uniquely qualified to review this vessel's configuration because it is the only classification society to have experience with the type of liquid gas containment system being used for the SANHA LPG FPSO. The vessel will utilize Ishikawajima Harima Heavy Industries, Co., Ltd's. ( IHI) Self-supporting, Prismatic-Shape, IMO Type-B tank system or SPB. ABS has previously classed the only LNG carriers to use this containment system and also classed the first LPG FSO newbuild, the Escravos, which is fitted with SPB tanks. The Escravos is in service for ChevronTexaco offshore Nigeria.
Unlike LNG, which is primarily methane that must be stored at extremely low temperatures (-260o F), LPG is primarily propane, which can be stored at a much higher or warmer temperature (-56o F). Although the main gas compound is different, the key issues for safe storage and transportation for both gases in the liquefied form are storage temperature and the gas containment system.
The SPB gas containment system is recognized by industry as particularly effective for liquid gas storage on an FPSO or FSO because of its internal tank stiffening structure and suitability for partial loading.
ABS offices worldwide will be involved in the project with engineering services and review being provided by staff in Houston, Yokohama, London and Hamburg. "It will take a worldwide coordinated effort drawing upon the various expertise of our engineers and close coordination with our surveyors," said Phil Rynn, ABS Project Manager for the SANHA LPG FPSO. Included in the scope of work will be design review of the following: topsides, pressure vessels in accordance with ASME standards, hull structure and cargo tanks, refrigeration and reliquefaction plants and turret and mooring assessment.
Mitsui & Co. Ltd. and IHI have signed the contract for the construction of the SANHA for Single Buoy Mooring Inc. of Monaco. The project will be operated by Sonangol (national oil company of Angola), ChevronTexaco, TotalFinaElf and Agip. The project is scheduled for completion mid 2004 with the first product shipped the beginning of 2005.
ABS classification of the SANHA will be: A1 Liquefied Petroleum Gas Floating Processing, Storage and Offloading System; Floating Offshore Installation-Depropanizer, Refrigeration and Reliquefaction Facilities, DLA, SFA; ACCU (Minus Propulsion).
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