ClassNK Greenlights Ammonia Fuel Tank Design for GSC’s Containerships

ClassNK has awarded an approval in principle (AiP) for the design of a prismatic ammonia fuel tank (IMO Type B independent tank) for containerships developed by Planning and Design Center for Greener Ships (GSC).

The Type B tank developed by GSC has been designed to ensure safe storage of ammonia and to minimize the reduction in the number of cargo containers due to the placement of fuel tanks in consideration of operational needs.

Furthermore, the shape of the storage space for the tank has been simplified from the typical bench corners for container carriers, improving constructability and increasing the fuel volume.

Ammonia is expected to be used as a marine fuel for shipping decarbonization since it does not emit CO2 when combusted. 

However, its utilization presents challenges, such as the risk of leakage and relatively low volumetric efficiency, according to ClassNK.

Type B independent tank (Credit: GSC)

While Type B tanks require a refined fatigue analysis, it is possible to use ordinary steel as the material for the structure of fuel storage hold space, except for the bottom part which is intended to be a partial secondary barrier, resulting in a reduction in the amount of steel for low temperature service.

Additionally, prismatic tanks offer superior volume efficiency compared to cylindrical tanks as they can be designed to fit the ship's hold.