ClassNK grants Approval in Principle (AiP) for methane oxidation catalyst system to Mitsubishi Heavy Industries Marine Machinery & Equipment and Mitsubishi Shipbuilding

- certificate handover ceremony was held in Sea Japan 2026 

From right:

Mr. Shin Ueda, President & CEO, Mitsubishi Shipbuilding Co., Ltd.

Mr. Katsuhide Matsunaga, President & CEO, Mitsubishi Heavy Industries Marine Machinery & Equipment Co., Ltd.

Mr. Masaki Matsunaga, Executive Vice President, ClassNK

ClassNK has issued an Approval in Principle (AiP) for a methane oxidation catalyst system* to Mitsubishi Heavy Industries Marine Machinery & Equipment Co., Ltd. and Mitsubishi Shipbuilding Co., Ltd. The certification demonstrates its feasibility from regulatory and safety perspectives.

As efforts toward decarbonization accelerate, the development of alternative fuel vessels is progressing. In the operation of LNG-fueled engines, however, methane slip—unburned methane released into the atmosphere—remains a challenge. Methane has a particularly high global warming potential among greenhouse gases, and therefore, catalyst systems capable of reducing methane slip through oxidation have attracted increasing attention. This system was installed as a demonstration unit on the LNG bunkering vessel KEYS Azalea, constructed by Mitsubishi Shipbuilding Co., Ltd., and has been undergoing demonstration testing.

ClassNK reviewed the design concept of the system based on chapter 21 of part D of its ‘Rules and Guidance for the Survey and Construction of Steel Ships’. Upon confirming compliance with the prescribed requirements, ClassNK issued an AiP. This AiP demonstrates that the design is feasible for the intended application and contributes to the prevention of regulatory rework in subsequent stages as well as the reduction of the time required for classification approval.

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

■ Contact: ClassNK www.classnk.com