World first Self-supporting Prismatic-shape IMO type B (SPB) LNG Carrier named "POLAR EAGLE" has been delivered to Philips 66 Natural Gas Company and Marathon Oil Company in June 1993. The cargo containment system installed on board the vessel. SPB cargo containment system was developed by Ishikawajima-Harima Heavy Industries Co. Ltd (IHI) and fully complies with IMO Gas Carrier Code for a type B independ tank. "POLAR EAGLE" was constructed in our Aichi works and delivered 34 months after the contract of the vessel. Its performance was confirmed through various kinds of tests and inspections during construction of the vessel. Results of typical tests and inspections are introduced.


The world first LNG carrier has been constructed and delivered in June 1993. Its cargo containment system has been developed by IHI complying with IMO standards for Type B independent tanks and the performance was tested during construction of the vessel. In type B tank structure, the cargo tank has strong structure to bear liquid load contained in it and its strength including fatigue strength through ship's life is required to be fully analyzed. The stress analysis for the prismatic tank with stiffened plate structure is one of the key technologies of that SPB system. In that structural test of this vessel, stress distribution was measured and the reliability of applied analysis was confirmed. Tank support system shall be suitable for thermal movement of the tank as well as bear load of the tank. In SPB system, the tank support is so designed to allow thermal contraction and expansion of the tank freely, which results m less thermal stress of the tank, as well as to bear the load. This function was confirmed in the cool down test. Insulation system is required to protect inner hull from suffering lower temperature than designed and to maintain naturally evaporated boil-off gas within a predetermined rate and shall withstand thermal movements of the tank and the insulation itself.

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