Fracture And Leakage Analysis For Low-temperature Cargo Tanks Of Liquefied Gas Carrier

Liquefied gas carrier is mainly used to transport LNG,LPG,petrochemical products,chemical gas,liquid ammonia,etc.Membrane or independent cargo container system is usually used for liquefied gas carrier.In recent years,because of its relatively low cost,simple manufacturing process and lower evaporation rate,the industry shows more and more interest to Type-B independent cargo tank.At present,the research on Type-B tank is still in its infancy,and the public information is very few,so it is of great significance to study this subject.In addition,the new IGC explicitly requires that an initial surface flaw will not propagate more than half the thickness of the shell during the lifetime of the tank.Although the dynamic membrane stress has been considered in the design of pressure vessel,the performance of structure is uncertain when its size is very large.For safety reasons,the fracture mechanics performance of the structure under alternating loading needs to be evaluated.In view of this,based on the fracture mechanics,LBB criterion and relevant rules and specification of gas carrier,a completely method of crack propagation and leakage analysis for independent cargo tank has been form.In this paper,special calculation software is developed with VB language and used to calculate the actual ship,and the calculation results are analyzed and some conclusions are drawn.