Study on Characteristics of Through-Thickness Crack When Cryogenic Materials are Applied to Independent B Type Tank

Abstract

Due to climate change, interest in eco-friendly energy is continuously increasing around the world. LNG is an intermediate energy source and its use increases continuously because of its established infrastructure. LNG temperature is -165°C and requires low temperature toughness of tank material. High manganese austenitic steel has similar mechanical properties to cryogenic material for LNG listed in IGC and IGF code. High manganese austenitic steel easily satisfies the low temperature toughness required at cryogenic temperature and shows superior performance in yield strength, tensile strength and elongation, compared to existing materials in IGC and IGF code.</br>In this study, the thickness ratio is reviewed while loading the same LNG fuel. Based on the thickness ratio, the thickness for 9%Ni steel, STS304 and Al5083 is calculated for two standard thickness of 10 mm and 20 mm for the high manganese austenitic steel. 9%Ni steel, STS304, Al5083 and high manganese austenitic steel are compared and reviewed from the viewpoint of the required time for initial surface cracks to grow into through-thickness cracks and the size of through-thickness cracks under the same amount of LNG fuel. The effect of different thickness, welded joint and stress sequence on through-thickness cracks are investigated.