ClassNK has granted a General Design Approval (GDA) for a low-pressure liquefied CO2 cargo tank developed by Mitsubishi Shipbuilding Co., Ltd. This approval confirms the tank’s adherence to relevant regulations at the detailed design stage, marking a world first for a tank constructed from KF460 steel that utilizes technology to eliminate the need for post-weld heat treatment (PWHT).
The GDA incorporates a safety assessment process based on Engineering Critical Assessment (ECA), a fracture mechanics technique that allows for the omission of PWHT—a common bottleneck in tank manufacturing. In September 2024, ClassNK issued an Approval in Principle (AiP) for Mitsubishi’s ECA evaluation process. Following a thorough design evaluation and material property assessment of the new steel developed by Nippon Steel Corporation, ClassNK verified the tank’s structural integrity under specified design temperature conditions.
This review was conducted in alignment with Part N of ClassNK’s ‘Rules and Guidance for the Survey and Construction of Steel Ships’. Upon confirming that the tank meets all necessary requirements without PWHT, ClassNK issued the GDA, representing a significant milestone in the approval of LCO2 cargo tanks. ClassNK remains committed to supporting advanced carbon-neutral initiatives through rigorous safety assessments and evaluations.
