ClassNK updates safety guidelines for alternative-fuelled ships

Classification society ClassNK on Tuesday (18 August) said it has revised the safety requirements within its guidelines for ships using methanol, ethanol and hydrogen as marine fuels. 

In Part D of the guidelines, covering hydrogen-fuelled ships, the revision incorporates the Interim Guidelines for the Safety of Ships Using Hydrogen as Fuel (MSC.1/Circ.1701) issued by the IMO this year, and additionally introduces a hydrogen leak frequency table that can be used for the safety assessments required under the IMO guidelines. 

In Part A, covering methanol and ethanol-fuelled ships, new structural strength requirements for methanol/ethanol fuel tanks—which are not addressed in the IMO guidelines—have been established. 

“Through this revision, shipyards, designers, and shipowners can carry out design and safety assessments in line with the latest international standards, and by utilizing ClassNK’s own leak frequency estimates and the relevant requirements, they can proceed the development of alternative-fuelled ships in a more rationally,” ClassNK said in a statement. 

As the building of alternative-fuelled ships advances in response to the global challenge of reducing GHG emissions, ClassNK has comprehensively compiled the safety requirements for ships using methanol, ethanol, LPG, ammonia, and hydrogen—fuels regarded as promising alternatives—and has issued the guidelines. 

“Taking into account the risks that the use of alternative fuels poses to the environment, seafarers, and ships, the guidelines set out requirements for equipment, controls, and safety devices to minimize such risks,” it added. 

With the issuance of the IMO guidelines for hydrogen-fueled ships (MSC.1/Circ.1701), ClassNK said it has fully incorporated the IMO guidelines to make the guidelines more user-friendly for shipyards, designers, and shipowners, while also enhancing the requirements serving as design and assessment guidance for other alternative fuels. 

In the development of the IMO guidelines, now reflected in Part D, ClassNK participated as a member of the Japanese delegation to the IMO Sub-Committee CCC 11 and contributed to the discussions.

Note: The Guidelines for Ships Using Alternative Fuels (Edition 3.1)  can be viewed under “Guidelines” on My Page by registering as a user on the ClassNK website. 

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Published: 20 August, 2026