Press Release

3 December 2025

Tokyo - ClassNK has issued an Approval in Principle (AiP) for Spray form insulation system of IMO Type B tank* for LNG and Ammonia Fuel developed by Nihon Shipyard Co., Ltd. and Hankuk Carbon Co., Ltd. The certification demonstrates its feasibility from regulatory and safety perspectives.

As the maritime industry faces the pressing challenge of decarbonization, the development of alternative-fuel vessels powered by LNG and ammonia is gaining momentum. Traditionally, IMO Type C tanks* have been the mainstream choice for LNG-fueled ships due to their advantages in productivity and cost. Meanwhile, for the large-capacity fuel tanks required on large container ships and ammonia-fueled vessels, IMO Type B tanks are gaining recognition as an alternative, offering superior cargo efficiency and outfitting flexibility.

For the design concept and result of demonstration mock-up test for the Spray form insulation system of IMO Type B tank, ClassNK conducted its safety review based on the part N of its "Rules and Guidance for the Survey and Construction of Steel Ships", which incorporates the IGC Code, and also the part GF, which incorporates the IGF Code. Upon confirming its compliance with the prescribed requirements, ClassNK issued the AiP.

ClassNK will continually strive to contribute to advanced decarbonization initiatives through safety assessments and more.

* One of the independent tank types defined under the IGC Code, the international code for the construction and equipment of ships carrying liquefied gases such as LNG in bulk.


AiP Handover Ceremony

Right: Mr. Moon-soo Cho, CEO, Hankuk Carbon
Center: Mr. Tomoaki Takahira, Director, Chief of Design Division, Nihon Shipyard
Left: Mr. Masaki Matsunaga, Executive Vice President, ClassNK

Approval in Principle (AiP):
At the initial stage of designing or before the specific target ship to be implemented is decided, the design is examined based on the existing regulations such as international conventions and ship classification rules, and an Approval in Principle (AiP) is issued as proof of conformity with requirements. It also prevents rework of regulatory aspects in the post-process, shortens the examination time at the time of class registration, and can be used as a technical basis for external appeal of the design status. For more information, visit our  website.

Nihon Shipyard Co., Ltd.:
Niho n Shipyard Co., Ltd. was founded in 2021 as a “sales and design company for all general commercial ships and offshore floating structures, excluding LNG carriers,” through a joint investment by Imabari Shipbuilding Co., Ltd. and Japan Marine United Corporation.
Website: https://www.nsyc.co.jp/en/

Hankuk Carbon Co., Ltd.:
Hankuk Carbon is a composites manufacturer founded in 1984 in South Korea. They supply various materials via prepreg, including carbon fiber and glass fiber, to a wide range of high-tech industries.
Website: https://www.hcarbon.com/en/main.do


For inquiries about this press release:
ClassNK Hull Department
Tel: +81-3-5226-2017
E-mail: hld@classnk.or.jp

For media-related inquiries:
ClassNK Public Relations Team
4-7 Kioi-Cho, Chiyoda-Ku, Tokyo 102-8567 Japan
E-mail: eod@classnk.or.jp

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