Marine fuel LNG tanks are designed as cryogenic pressure vessels, using conventional pressure vessel codes, and the dominant design criteria is the vapour pressure. This type of containment system can be used for fully pressurized, semi-pressured and fully refrigerated gas carrier and LNG fuel tank. It is the dominant design in LNG carriers. There are two types of insulation used, double shell with vacuum and insulation in annular space and single shell with spray insulation on the outer layer to hold the low temperature. Mainly tank material made of 9% Ni steel.