A bulk carrier adopting NSafe®-Hull first in the world has recently been launched for Mitsui O.S.K. Lines, Ltd. NSafe®-Hull (a highly ductile steel plate for shipbuilding with improved collision safety) was developed by Nippon Steel & Sumitomo Metal Corporation (NSSMC) and adopted through the collaborative research and development (R&D) by NSSMS, Imabari Shipbuilding Co., Ltd., and the Japan’s National Maritime Research Institute (NMRI).
NSafe®-Hull is described as having excellent ductility, while maintaining the workability (e.g., machinability and weldability) of conventional steels, which substantially improves ship’s collision safety. NSSMC developed NSafe®-Hull through designing chemical composition and microstructural control in crystalline scale.
If a ship is made of NSafe®-Hull, because of superior ductility of the material, the energy absorbed before breaking hull could be roughly triple the amount that that of made of conventional steels, in case of side collision. It can therefore be said that NSafe®-Hull increases ship durability compared with conventional steels.
On the ship for Mitsui O.S.K. Lines, Ltd., approximately 3,000 tons of NSafe®-Hull, in total, was used for structural parts where high collision safety performance was required, such as the side plates of cargo holds and fuel tanks.
NSafe®-Hull, if used for ship’s structure, owing to its improved anti-breaking performance in case of collision, contributes to preventing oil leakage resulting in environmental pollution and ingress of water into cargo holds, which directly leads to cargo damage and may result even in capsize.
Further advanced analysis is planned to be conducted with the support of the “Joint R&D with Industries and Academic Partners” scheme of Nippon Kaiji Kyokai (ClassNK). ClassNK is, in addition, considering assigning notations to ships with higher safety, such as for ships in which NSafe®-Hull is used, in order to further improvement on ship safety.