IMO independent type B LNG tanks are designed using model tests, refined analytical tools and analysis methods to determine stress levels, fatigue life and crack propagation characteristics. Currently the tank design is performed based on the mechanical properties of the tank materials at room temperature. However it is notable that the materials used for the tanks show enhanced yield and tensile strength at low temperature and this design advantage can be taken into account when giving further consideration to fatigue fracture and crack propagation characteristics. In this study, the application of cryogenic design criteria to an SPB (Self-supporting Prismatic IMO type B) LNG tank made of SUS304(Mod) is presented. The material properties of SUS304(Mod) have been obtained from a series of tensile, fatigue and crack growth rate tests at 25°C, −100°C and −163°C. A design temperature that takes account of the cryogenic operating environment is proposed and the estimation of the weight reduction compared to a room temperature design is also described.

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