Influence of welding residual stress on cryogenic materials applied to LNG fuel tanks for coastal vessels

Abstract

The purpose of this paper is to investigate the influence of welding residual stress (WRS) of the liquefied natural gas (LNG) fuel tank. In general, WRS and distortions are caused by non-uniform temperature distribution by the welding heat source. This will not only cause a brittle fracture, local buckling and corrosion damage, but also adversely affect the fatigue strength of the welded structures. Since LNG is treated at cryogenic temperatures of −162[Formula: see text]C, leakage of LNG from the fuel tank to the outside may cause cracks in the hull and tank support system and cause severe damage. Therefore, it is necessary to predict the thermal behavior and WRS before welding is carried out. In this study, the WRS is calculated by thermal stress analysis based on the temperature distributions over time obtained from the transient thermal analysis. The results of this study can be used as a fundamental research for WRS analysis of plasma arc welding applied to LNG fuel tanks for coastal vessels.