Based on the analyses of the containment system of a new independent type B liquefied natural gas(LNG)carrier with the total capacity of 17×104 m3

by comparing with the containment systems of traditional membrane-type and MOSS independent spherical type LNG carriers

the features of the new independent type B containment system are expressly highlighted.Based on the analyses of the hull and containment system structures of this LNG carrier

by taking into account of some reasonable and necessary simplification

a numerical simulation method is provided to calculate the heat transfer and the boil off rate of the containment system under different working conditions.And the effect of the thermal conductivity of reinforced polyurethane foam(RPUF)insulation material on boil off rate is studied.The following conclusions are obtained: (1)Given many advantages of the new independent type B containment system compared to traditional ones

this type of containment system has a promising application prospect in future.(2)When the thickness of insulation layer is 450 mm

the thermal conductivity of insulation material should be no larger than 0.03 W·m-1·K-1

in order to meet the requirement that the boil off rate is less than 0.1% per day.