ClassNK has released Edition 3.1 of its Guidelines for Liquefied Hydrogen Carriers , updating safety requirements for the transport of liquefied hydrogen. The revised guidelines incorporate the Revised Interim Recommendations for Carriage of Liquefied Hydrogen in Bulk , adopted by the IMO in 2026. New requirements for membrane systems The update introduces requirements for liquefied hydrogen carriers fitted with membrane-type cargo containment systems using vacuum insulation . The requirements cover vacuum insulation systems, monitoring devices, pressure control equipment and emergency response. ClassNK said the changes will help shipyards, designers and shipowners assess new liquefied hydrogen carrier designs and prepare for flag administration approval. Materials and welding guidance strengthened ClassNK has also updated its guidance on metallic materials, testing, welding and quality control for hydrogen equipment. The revised guidance addresses risks including low-temperature embrittlement, hydrogen embrittlement and hydrogen attack . According to ClassNK, the changes are based on experience gained through design reviews and technical assessments of actual projects. The classification society said the revisions are intended to reduce the risk of design changes and additional verification during vessel development. Hydrogen carrier designs continue to evolve ClassNK said liquefied hydrogen carrier designs are becoming more diverse as development of large-scale hydrogen transportation advances. The latest guidelines also reflect knowledge gained through the construction and operation of demonstration vessels, as well as research and development projects. ClassNK said it will continue developing standards and providing certification and technical information to support maritime stakeholders working on environmental technologies. The post ClassNK updates safety rules for membrane-type hydrogen carriers appeared first on Container News .