ClassNK has published the third revision, labelled Edition 3.1, of its Guidelines for Liquefied Hydrogen Carriers, bringing the society's technical guidance into alignment with recent international recommendations.
The release was reported on 11 September 2026. The revision incorporates the ‘Revised Interim Recommendations for Carriage of Liquefied Hydrogen in Bulk’, which were adopted by the International Maritime organisation in 2026.
Edition 3.1 updates the existing safety requirements for liquefied hydrogen carriers. Among the changes are specific guidance provisions on the selection of materials and on welding practices for hydrogen equipment.
The guidance on materials selection and welding practices is presented as part of a broader update to safety criteria. The society frames these technical elements as necessary details within the revised document, intended for stakeholders engaged in design, construction and operation of hydrogen carriers.
ClassNK’s update is directed at a range of maritime stakeholders. The revision is intended to help shipyards, designers, shipowners and other maritime parties obtain a clearer understanding of the amended safety requirements.
The publication of Edition 3.1 follows the IMO adoption noted above and represents a formal step by the classification society to translate those international recommendations into practical guidance. reports supplied the initial report of the release on 11 September 2026.
What Edition 3.1 incorporates
The central technical change in Edition 3.1 is the incorporation of the IMO’s Revised Interim Recommendations for Carriage of Liquefied Hydrogen in Bulk adopted in 2026. This incorporation is described in the society’s updated guidance and is presented as the basis for the revised safety requirements.
The updated guidance explicitly addresses the selection of materials and welding practices for hydrogen equipment. These topics are set out within the revision as part of the safety-related material in the new edition.
Who the revision is aimed at
ClassNK’s Edition 3.1 is aimed at organisations involved in the creation and operation of liquefied hydrogen carriers. The society identifies shipyards, designers, shipowners and other maritime stakeholders as those who can use the guidance to gain a clearer understanding of the revised safety framework.
Those groups are pointed to the updated requirements and the technical guidance contained within Edition 3.1 as a means of aligning design and construction practices with the IMO’s 2026 recommendations.
The reports item dated 11 September 2026 provides the published notice of the release. The report presents the revision as a consequential update to the earlier guidance and as reflecting the international recommendations adopted by the IMO in 2026.
Edition 3.1 therefore represents a current reference from ClassNK that brings its guidance into line with the latest interim recommendations on carriage of liquefied hydrogen in bulk as adopted at international level. The society’s update emphasises the material and welding aspects of hydrogen equipment as part of the amended safety requirements.
A number of stakeholder groups are explicitly named in the release as potential users of the updated guidance. Shipyards, designers and shipowners are cited alongside a broader category of maritime stakeholders who may consult the revision to clarify requirements for liquefied hydrogen carriers.
reports is the outlet that reported the release on 11 September 2026, summarising the revision and its relationship to the IMO’s 2026 recommendations. The society’s Edition 3.1 stands as the latest published guidance from ClassNK addressing technical and safety matters for liquefied hydrogen carriers.