SAFETY ASSESSMENT OF CARGO CONTAINMENT SYSTEMS IN LNG CARRIERS UNDER THE IMPACT OF ICEBERG-SHIP COLLISION

摘要

Arctic and sub-arctic regions of Russia are home to some of the large gas reservoirs, attracting numerous energy development projects. A ship-borne transportation system connecting these potential gas fields to gas terminals in Gulf of Mexico will likely be established. In this case, the integrity and safety of LNG cargo containment systems under impact of the iceberg-ship collision should be carefully considered at conceptual and detailed design phase. The collision impact by an undetected iceberg should be considered to be an accidental load. Thereby, plastic deformations of the hull structure may be accepted provided the LNG will not leak out. Till now, view points of the safety evaluation have been limited to structural hull deformations by the collision. They have not examined effects of vibratory acceleration induced by the impact on the structure of LNG containment systems, even though it seems rather rational in case of substructure such as LNG containment systems in independent type or membrane type LNG carriers. In this paper, the iceberg-ship collision scenario is established based on International Ice Patrol's reports. The comparative safety assessment of cargo containment systems for independent type (spherical and SPB) and membrane type (Mark-Ill and NO96) LNG carriers is performed through a computational simulation and the related experimental research works.