ClassNK type approves corrosion-resistant steel for cargo oil tanks

Japanese classification society Nippon Kaiji Kyokai — ClassNK — has issued the world’s first type approval for corrosion resistant steel to the new NSGP-1 steel manufactured by Nippon Steel Corporation’s Oita Works.

The approval certifies that the new steel, which has been specifically designed for application on the inner bottom of the cargo oil tanks of crude oil tanker, complies with the new IMO performance standard for corrosion resistant steels.  

New requirements for preventing corrosion in the cargo oil tanks of crude oil tankers were adopted by the IMO’s Maritime Safety Committee (MSC) at its 87th meeting in May 2010. Under the new regulations, crude oil tankers over 5,000 deadweight tons contracted for construction after January 1, 2013, will be required to apply either protective coatings or corrosion resistant steel to the inner surfaces of the cargo oil tanks. Demand for such steels is expected to grow since their use eliminates the need for the expensive facilities, preparation and finishing work associated with coating application while also reducing the need for maintenance and coating reapplication.
Nippon Steel’s NSGP-1 steel has been specifically designed for application on the inner bottom of crude oil tanker cargo oil tanks, and verification tests onboard vessels have confirmed that the steel resists the corrosive environment found in the bottom of crude oil tanker cargo oil tanks.

As part of the type approval process, ClassNK confirmed that the new steel meets the requirements of both the IMO’s performance standard for corrosion resistant steels, as well as ClassNK’s Guidelines on Corrosion Resistant Steel for COT. The approval further certifies that the steel has sufficient corrosion resistant properties for application on the inner bottom of the COT, and maintain the same mechanical properties and weldability as regular steels used in the construction of hull structures.

In addition to this first type approval granted to Nippon Steel Corporation’s NSGP-1 steel, Class NK released the world’s first guidelines for the manufacturing and application of corrosion resistant steels in December 2010 and granted the first class approval for systems to test such steel’s corrosion performance earlier this month. With the demand for these new steels expected to increase rapidly in the near future, ClassNK is working with manufacturers, shipyards, and owners to ensure that the new steels can be manufactured, applied, and maintained to the highest standards possible.

April 27, 2011