When considering the use of non-standard/alternative materials for IGC/IGF code applications, the IMO MSC.1/Circ.1622 – Guidelines for the Acceptance of Alternative Metallic Materials for Cryogenic Service in Ships Carrying Liquefied Gases in Bulk and Ships Using Gases or Other Low-Flashpoint Fuels, provides a framework to be followed.
For LR acceptance of these materials, this Guideline Note provides detailed information regarding the approval, testing and certification of metallic materials in order to assess their suitability for low temperature and cryogenic service.
This document only applies to alternative metallic materials formed or manufactured by rolling, extrusion, casting or forging. It also provides additional compatibility test requirements for both base and welded materials considered for ammonia service. The application of alternative metallic materials approved under this Guideline Note is to be restricted to specific projects where the use of the material has been subject to LR plan appraisal and the approval of the flag administration or a recognised organisation acting its behalf. Specific information on the requirements for the approval of works for the manufacture of alternative metallic materials, including the works approval process and documents, is also available.
This guidance does not address material forming part of the hull structure.