A joint project between class society Korean Register (KR) and South Korea’s Hyundai Mipo dockyard (HMD) has resulted in approval in principle (AiP) to use IMO type-B prismatic tank technology on a 30,000-m3 newbuild LNG carrier
Prior to KR’s AiP for the LNG carrier being designed at HMD, the type-B tanks have been typically used with larger LNG carriers, a statement from KR said.
"KR has carried out the cargo hold fatigue analysis, the crack propagation analysis and gas leakage rate calculation and has verified the new LNG carrier’s compliance with the IGC Code (the International Code for the Construction and Equipment of Ships carrying Liquefied Gases in Bulk)," the statement said.
According to KR, there is growing interest in applying membrane-type hull and cargo hold technology to small and medium-sized LNG carriers to meet increasing demand for LNG and the expansion of LNG bunkering infrastructure.
"The advantage of the HMD type-B tank lies in the possibility of a separated design for the hull and the cargo tank, ensuring appropriate structural stability inside the tank to manage the impact load caused by the motion of the liquid cargo, and through its design flexibility as a fuel tank," the class society said.
Designing the LNG cargo tank for a smaller vessel required crack propagation analysis and installing a partial drip tray in the lower section of the LNG cargo tank after calculating the amount of gas that will escape from the structure supporting the cargo tank, according to KR.
"The partial second barriers have made it difficult to design this type B cargo tank, but the potential high hull space utilisation has driven the development of this technology. We expect increasing demand for small and medium-sized LNG carriers in the future as a direct result of this AIP," HMD executive vice president Nam Young-joon said.
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