South Korean steelmaker POSCO and shipbuilder Hanwha Ocean have signed a memorandum of understanding (MoU) to develop a demonstration liquefied natural gas (LNG) carrier equipped with cargo tanks made from high-manganese steel.
Under the agreement, signed at Hanwha Ocean’s shipyard in Geoje, POSCO will supply its proprietary high-manganese steel technology, while Hanwha Ocean will lead construction of the demonstration vessel. The carrier will be tested under actual sailing conditions to establish the technology’s performance and build a track record for potential adoption by shipowners worldwide.
According to POSCO, high-manganese steel retains its strength and impact resistance at temperatures of minus 163 degrees Celsius and below, making it suitable for LNG storage. The material has previously been used in LNG fuel tanks, but the project aims to extend its application to cargo tanks on LNG carriers.
POSCO said an LNG carrier’s cargo tanks can require 10,000 tons of steel or more, around 10 times the amount needed for LNG fuel tanks. The development could therefore expand the market for the steelmaker’s technology and help South Korean shipbuilders reduce their reliance on foreign cargo tank technologies.
POSCO is one of the world’s largest steel producers, with crude steel output of 33.2 mln tons in 2025. The company operates integrated steelworks in Pohang and Gwangyang and is investing heavily in low-carbon steelmaking technologies, including EAF and hydrogen-based iron production.