Materials Distribution of Cargo Tank Saddle and Nearby Hull Structure of Small and Medium LNG Carrier

The C-shape independent liquid cargo tank,the main liquid tank form of the small and medium LNG carrier,is a semi-chilled and semi-compressed container.Because of the low temperature around the liquid tank,which load s LNG and is supported by the saddle connected with hull structure,temperature gradient will be formed on the saddle and nearby hull structure.So it is necessary to analyze the temperature field about the saddle and ne arby hull structure so as to determine the material distribution.The thermal analysis method for the saddle of the C-shape independent liquid cargo tank and nearby hull structure is proposed.It is considered that the b earing of the cargo tank and the nearby hull structure is surrounded by the three mediums,low-temperature liquid cargo,seawater and air,and achieves heat balance by convective heat transfer between hull and the three m ediums and the heat conduction between hull and laminated wood.With the FEM software ANSYS,a simplified model for thermal analysis and the approach to applying convection load is given to determine the temperature fiel d layout of the saddle and nearby hull structure.Meanwhile,combining with the allowable design temperature of the materials,the suitable materials distribution is given,which can prevent the material from the low-tempe rature break.An instance is given which is a meaningful attempt to solving the problem of the material distribution for the bearing and nearby hull structure surrounded by the low temperature.