ClassNK updates its guidelines for liquefied hydrogen carriers

Japanese classification society ClassNK has released the third edition of its guidelines for liquefied hydrogen carriers, which cover “essential” details to examine the safety of liquefied hydrogen carriers to spur related technological developments.

According to ClassNK, the development of these carriers that enable large-scale and “efficient” transportation is progressing actively.

The classification society mentioned the work of the International Maritime Organization (IMO) on establishing safety requirements for liquefied hydrogen carriers that must keep cargo at an extremely low temperature of minus 253 degrees Celsius. The resolution “Interim Recommendations for Carriage of Liquefied Hydrogen in Bulk” was adopted in 2016.

Subsequent development of liquefied hydrogen carriers led to the construction project of a larger-scale liquefied hydrogen carrier with cargo containment systems of different designs from a prototype liquefied hydrogen carrier, ClassNK said, adding that in response to this, at the IMO, discussions for the revision of the interim recommendations have been underway since 2021.

ClassNK has been contributing to these discussions, and in light of the revised interim recommendations being adopted, it has updated its guidelines as edition 3.0.

In this update, new safety requirements for cargo containment systems with different designs from an existing prototype liquefied hydrogen carrier were added, and the guidelines’ structure was reformed in anticipation of a future expansion of the applicable scope. Furthermore, to clarify the selection criteria for metallic materials suitable for liquid hydrogen carriers, an annex of guidance for the selection of metallic materials for hydrogen equipment was also newly implemented.

ClassNK stated: “It is believed that the safety of liquid hydrogen carriers is adequately ensured through compliance with each safety requirement and implementation of safety measures based on risk assessment, in accordance with the provisions of the guidelines.”

To remind, in 2024, ClassNK also published a new edition of its guidelines for ships using alternative fuels, which outline the safety requirements for ships using methanol, ethanol, LPG and ammonia as fuel. The new release contains requirements related to hydrogen-fueled ships, providing guidance for the design of alternative-fueled ships.