ClassNK has issued a General Design Approval (GDA) for Low-pressure LCO2 Cargo Tank developed by Mitsubishi Shipbuilding Co., Ltd. This approval verifies the tank’s compliance with relevant rules at the detailed design level*1. GDA for a liquefied CO₂ cargo tank made of KF460 steel and applying technology that omits PWHT*2 marks the world’s first case.
This GDA includes a tank safety assessment process based on a fracture mechanics technique called Engineering Critical Assessment (ECA)*2 to omit post-weld heat treatment (PWHT)*3, which can be a bottleneck in tank manufacturing. An Approval in Principle (AiP) for Mitsubishi Shipbuilding’s ECA evaluation process was issued in September 2024*4.
Based on the detailed design evaluation conducted by the Company and the material property assessment for a new steel conforming to NK standard ‘KF460’ developed by Nippon Steel Corporation, the structural integrity of the tank under the specified design temperature conditions has been demonstrated through ECA. In light of these assessments, ClassNK conducted a review of the tank in accordance with Part N of its ‘Rules and Guidance for the Survey and Construction of Steel Ships’. Upon confirming that the tank meets the prescribed requirements even without PWHT, ClassNK has issued the GDA. This marks the first time ClassNK has issued a GDA for a LCO2 cargo tank.
ClassNK will continually strive to contribute to advanced carbon neutral initiatives through safety assessments and more.
Source: ClassNK
