Structural Assessment of an IMO Type C Tank for Liquefied CO2 Storage Under Classification Rule-Based Load Conditions

This study presents a structural integrity evaluation of a 5000 m3 IMO Type C independent tank designed for storing liquefied carbon dioxide (LCO2) at −35 °C and 15 barg, based on the IMO IGC Code and Korean Register (KR) rules. A finite element model was developed to assess structural responses under representative load cases considering thermal contraction, internal pressure, and ship-induced accelerations. The results show that structural design is predominantly governed by the internal pressure associated with liquefaction conditions and boil-off gas (BOG) accumulation, rather than the minimum design pressure specified by classification rules or liquid head pressure. As a result, the required tank thickness approaches the upper practical limit (approximately 50 mm), leading to inherently sufficient buckling resistance without additional design constraints. These findings indicate that, under medium-pressure LCO2 storage conditions, Type C tank design is primarily pressure-driven, and structural stability can be effectively ensured through thickness design. The study provides practical insights into governing design factors for rule-based tank design and highlights key considerations for LCO2 storage applications.