ClassNK has revised the safety requirements for ships using methanol/ethanol and hydrogen as fuel within the ‘Guidelines for Ships Using Alternative Fuels (Edition 3.1).’
In Part D, covering hydrogen-fuelled ships, the revision incorporates the Interim Guidelines for the Safety of Ships Using Hydrogen as Fuel (MSC.1/Circ.1701) recently issued by IMO, 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/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 using ClassNK’s own leak frequency estimates and the relevant requirements, they can proceed the development of alternative-fuelled ships more rationally.
As the building of alternative-fuelled ships advances in response to the global challenge of reducing GHG emissions, ClassNK has comprehensively compiled safety requirements for ships using methanol, ethanol, LPG, ammonia, and hydrogen—fuels regarded as promising alternatives—and has issued these guidelines.
Examples of revisions include:
- Hydrogen-fuelled ships (Part D): The relevant IMO guidelines (MSC.1/Circ.1701) have been incorporated, and a full-scale revision has been carried out. In addition, as with the estimation of ammonia leak frequency, a Bayesian method was applied to derive estimated hydrogen leak frequencies for ships, which have been added as Appendix 2 to Part D. These enable ship designs and their safety assessments—required for administration approval of alternative-fueled ships—to be conducted in a more rational and reliable manner.
- Methanol/ethanol-fuelled ships (Part A): Based on ClassNK’s experience in the design review of such ships, structural strength requirements for methanol/ethanol fuel tanks—which were not specifically stipulated in the relevant IMO guidelines (MSC.1/Circ.1621)—have been developed and standardized. This enables the efficient implementation of tank design assessments.
As a third-party certification body, ClassNK says it will continue to support efforts to address environmental challenges through the development of standards, certification, and the provision of information.
The guidelines can be viewed by registered users on the ClassNK website.
