ClassNK has issued an Approval in Principle (AiP) for an ammonia-fuelled Panamax bulk carrier equipped with an IMO Type B independent fuel tank, marking what it described as the world’s first AiP for a ship with Type B tanks installed on the exposed deck.

The design was developed by the Planning and Design Center for Greener Ships, with the certificate handover taking place at Sea Japan 2026.

Class NK highlighted that the approval demonstrates the design’s feasibility from regulatory and safety perspectives.

The Japanese classification society noted that IMO Type C tanks have traditionally been the primary choice for ammonia-fuelled ships and other alternative-fuel vessels due to their advantages in productivity and cost-effectiveness. For the larger-capacity fuel tanks required on ammonia-fuelled ships, however, IMO Type B tanks are gaining recognition as an alternative offering improved cargo efficiency and outfitting flexibility.

The organisation reviewed the design against its Guidelines for Ships Using Alternative Fuels and the relevant Rules and Guidance for the Survey and Construction of Steel Ships. After confirming compliance with the prescribed requirements, it issued the AiP.

IMO Type B tanks are one of the independent tank types defined under the IGC Code, the international code covering the construction and equipment of ships carrying liquefied gases such as ammonia and LNG in bulk.

ClassNK stated that it will continue contributing to decarbonisation initiatives through safety assessments.