On the Strength Analysis of Insulation Structure for Spherical LNG Tank

Abstract

Authors developed an original insulation system named "KAWASAKI PANEL SYSTEM" for a LNG carrier with MOSS type spherical tanks and applied it to three LNG carriers successfully. This insulation system is composed of cellular plastic materials and metallic materials, whose properties are very complicated. The cellular plastic materials have temperature dependent and anisotropic properties. The metallic materials are wire net and very thin embossed aluminum sheet whose properties are dependent on the construction. This paper introduces FEM analysis which was carried out to clarify the behavior of such complicated composite insulation panel. In this analysis, Hill's yield criterion was applied to explain the failure of anisotropic polyurethane foam (PUF). Some tests including actual ship test were carried out to obtain back data for the FEM analysis. The results are as follows: (1) The FEM analysis is applicable to such complicated composite insulation panel which is composed of cellular plastic materials and metallic materials. The reliability of FEM was proved by experiments. (2) Hill's yield criterion can explain the failure of anisotropic PUF. (3) "KAWASAKI PANEL SYSTEM" has sufficient strength. (4) The design method using FEM can be utilized for the development of new insulation systems.