Reliability evaluation of a LNGC insulation system with a metallic secondary barrier

This study examined the fatigue performance of a LNG (Liquefied Natural Gas) insulation system with a newly developed metallic secondary barrier used in Mark-III type LNG carriers. In particular, the conventional secondary barrier used in Mark-III type carries a risk of leakage and fatigue failure owing to the thermal and cyclic loads. In this respect, the secondary barrier requires superior tightness, high strength, and fatigue performance at cryogenic temperatures. To improve the tightness and strength, the metallic secondary barrier was constituted of two aluminum foils, 0.08 mm in thickness, covered with glass fabric. A series of fatigue tests for the newly secondary barrier was carried out at room and cryogenic temperatures. In addition, the durability of the new secondary barrier was confirmed by a comparison of the fatigue performance of the conventional secondary barrier with that of the new proposed secondary barrier.