WELDED JOINT MANUFACTURING METHOD, WELDED JOINT, LOW-TEMPERATURE LIQUEFIED GAS TANK DESIGN METHOD, AND LOW-TEMPERATURE LIQUEFIED GAS TANK

This welded joint manufacturing method includes: a thermal stress calculating step for obtaining a thermal stress generated in a welded joint as a result of a difference between a linear expansion coefficient of welded metal and the linear expansion coefficient of a base material at a usage temperature of a low-temperature liquefied gas tank; a required CTOD value calculating step for obtaining a required CTOD value for preventing brittle fracture of the low-temperature liquefied gas tank during operation of the low-temperature liquefied gas tank, taking into account the effects of thermal stress, assuming a defect in the welded joint; a CTOD value measuring step for measuring the CTOD value of a heat affected zone of the welded joint at the usage temperature of the low-temperature liquefied gas tank; and a welding step for welding the base material, using, as the base material, a thick steel plate for which it has been confirmed that the CTOD value of the heat affected zone is equal to or greater than the required CTOD value.