Cryogenic reliability of the sandwich insulation board for LNG ship

Liquefied natural gas (LNG) is mainly carried by the LNG ship, whose cargo containment system is composed of dual barriers against the leakage of LNG and insulation board. The insulation board of LNG containment system should have cryogenic reliability and high thermal insulation performance for safe and efficient transportation of LNG. The polyurethane foam (PUF) reinforced with glass fiber (called RPUF) has been used for the insulation board to increase the fracture toughness of PUF. However, the RPUF not only increased the manufacturing cost of LNG ship, but also decreased the thermal insulation characteristics of PUF, which is a remaining concern in LNG ship building industries. In this study, the surface of PUF was reinforced selectively at the area under high thermal stress with glass composite to decrease the production cost and to increase the thermal insulation characteristics. Finite element analysis was conducted to estimate the thermal behavior of insulation board at the cryogenic temperature and a new experimental method was developed to investigate the reliability of insulation board based on fracture mechanics. From the experimental results, it was found that the selective reinforcing of the insulation board with the glass composite increased considerably the reliability at the cryogenic temperature.