IMO gives nod to high manganese austenitic steel for LNG tanks
Interim guidelines on the use of high manganese austenitic steel to LNG storage and fuel tanks have were approved at MSC 100.
High manganese austenitic steel was developed by POSCO, South Korea's largest steel maker for cryogenic use such as in LNG storage and fuel tanks in 2013. However, before the MSC's approval, only four types of material which included 9% nickel steel, aluminium alloy, stainless steel and Invar were authorised for use in the building of LNG tanks by the IMO. High manganese austenitic steel has many claimed advantages, offering reduced costs, low price volatility, and higher tensile strength compared to the other four alternatives.
Over the last year, classification society Korean Register (KR) has worked to develop the interim guidelines in close cooperation with the Ministry of Oceans and Fisheries of Republic of Korea and POSCO. The draft was agreed at the 5th Sub-Committee on the Carriage of Cargoes and Containers in September 2018, with final approval secured at the 100th MSC.
The first vessel to use high manganese austenitic steel for its LNG fuel tank was constructed at Hyundai Mipo Dockyard in July 2016. It is a 50,000 dwt LNG-fuelled bulker constructed in accordance with Harmonized CSR and classed by KR. KR conducted an intensive analysis to assess the safety of the base metal and welds, to ensure the safety of this vessel and to develop the exact specification for the high manganese austenitic steel. The completed vessel has been chartered by POSCO to transport limestone cargoes in the Korean coastal trade.
Changwook Kim, the head of KR's technical division and executive vice president of KR said: "With the MSC's approval, the industry now has more options to choose from when building LNG tanks and storages, with high manganese austenitic steel offering a cost effective and environmentally-friendly alternative. Furthermore, KR as a classification society, is now working to develop high manganese austenitic steel that complies with the IGC Code (International Code for the Construction and Equipment of Ships carrying Liquefied Gases in Bulk) and the IGF Code (International Code of Safety for Ships Using Gases or Other Low-Flashpoint Fuels) in near future."