LNG FPSO 화물창 재료의 상온 및 극저온 피로물성치

초록

Many concerns are focused on the SPB-type CCS (cargo containment system) for LNG FPSOs. This paper presents test results of the three materials of Al 5083-O alloy, SUS304, and 9% Ni steel, which are regarded possible candidates for the materials of SPB-type CCS. Extensive fatigue tests are carried out at room and cryogenic (-163°C) temperatures. Two types of specimens are prepared to identify the differences of fatigue characteristics: butt and longitudinal attachment weld joints. This paper suggests S-N parameters for each material and type of weld joint at room and cryogenic temperatures. Fatigue strengths increase according to the temperature decrease for three materials. Fatigue strengths of butt weld joints are stronger than those of longitudinal attachment weld joins. The lowest fatigue strength is observed in Al 5083-O alloy, meanwhile other materials show similar fatigue characteristics. But in a point of view for ratio of stress range to yield strength, 9% Ni steel shows the lowest fatigue strength.