With tougher environmental regulations being introduced around the world, it is imperative that the maritime logistics industry also become more sustainable.
There has been an increase in the number of ships that run on liquefied natural gas (LNG) instead of Bunker C oil. LNG becomes liquefied at temperatures below -163 ℃, so its transportation requires a storage tank that can withstand cryogenic conditions. Naturally, this creates increased demand for steel suitable for LNG transport and storage.
Embracing this international trend, Hyundai Steel developed a 9% nickel steel that withstands temperatures below -163 ℃ and is suitable for the storage and transport of LNG. The company already acquired a contract to supply this specialized steel for the building of two LNG-run, ultra-large container ships.
9% nickel steel is attracting attention as a necessary material for the manufacture of fuel tanks in LNG-run ships. For a fuel tank to reliably store LNG under cryogenic conditions, it must be made of an exceptional material with outstanding mechanical properties, such as rigidity and impact toughness at both normal and cryogenic temperatures.
At present, the materials that can be used to store LNG are 9% nickel steel, stainless steel, aluminum 5083, and Invar (36% nickel), as defined by international standards. What makes the 9% nickel steel developed by Hyundai Steel impressive is its durability, as it does not fracture even at -196 ℃. Its high nickel content gives it stability at cryogenic conditions even after being welded.
Nickel steel has a higher yield strength (the stress at which a predetermined amount of permanent deformation occurs) compared to other materials, which makes it ideal for making large structures such storage tanks to be exposed to high pressures.
Technical review and development of the newly formulated 9% nickel steel began in September 2018. Hyundai Steel subsequently concentrated its R&D capacity, including the formation and stabilization of operating standards, and in March 2020 achieved a consistent quality in the product. In December 2020, the 9% nickel steel was certified by the shipping authorities of nine key countries, including Korea, the US, Norway, and Germany. Hyundai Steel’s clients also completed their evaluations of the product in the same month, leading to contracts to use this new steel in the manufacture of fuel tanks for the LNG-run container ships being built by Hyundai Heavy Industries.