Nippon Steel & Sumitomo Metal : World-first Adoption of NSafe®-Hull — A New Plate for Shipbuilding with Improved Collision Safety

Aug. 05, 2014

Nippon Steel & Sumitomo Metal Corporation
Imabari Shipbuilding Co., Ltd.
 National Maritime Research Institute

World-first Adoption of NSafe®-Hull - A New Plate for Shipbuilding with Improved Collision Safety

A bulk carrier adopting NSafe®-Hull first in the world was launched on 2nd of August 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 (hereinafter "NSSMC", Representative Director and President: Kosei Shindo) and adopted through the collaborative R&D by NSSMS, Imabari Shipbuilding Co., Ltd. (President: Yukito Higaki) and the National Maritime Research Institute (hereinafter "NMRI", President: Kazuhiro Mori).

NSafe®-Hull has 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 of one for a ship made of conventional steels, in case of side collision. It can therefore be said that NSafe®-Hull increases ship durability compared with conventional steels.  Such higher safety level has been achieved by the cooperative research of the aforementioned three organizations on steel ductility and ship collision safety.

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.

Fig. 1: Overview of parts for which NSafe®-Hull was used (Parts in red and yellow)

Fig. 2: Sectioned view of parts for which NSafe®-Hull was used (Parts in red)

Fig. 3:  Ship side collision (schematic)

Fig. 4: Examples of collision simulations (1.4 seconds after collision at 12 knots, left: with NSafe®-Hull, right: with conventional steel)

NSSMC is planning to conduct more advanced analyses 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.

NSSMC, Imabari Shipbuilding Co., Ltd., and NMRI will continue contributing to safe, secured and environmentally friendly marine transportation by promoting the adoption of NSafe®-Hull for a wide variety of ships.

For more information, please contact:
NSSMC Public Relations Center, General Administration Div.,    TEL:+81-3-6867-5807
Imabari Shipbuilding Co., Ltd. Hull Design Group,                   TEL:+81-80-2851-9155
NMRI Public Relations, Planning Department,                          TEL:+81-422-41-3005