Global first! Daewoo Shipbuilding & Marine Engineering (DSME) equips ultra-large container ships with high-manganese steel LNG fuel tanks

On October 31, South Korea's Daewoo Shipbuilding & Marine Engineering (DSME) held a loading ceremony for installing high-manganese steel LNG fuel tanks on an LNG dual-fuel 24,000 TEU ultra-large container ship. This marks another new breakthrough for the company after successfully installing high-manganese steel LNG fuel tanks on an LNG-powered Very Large Crude Carrier (VLCC) for the first time globally in June this year.

It is understood that this vessel is the first of six LNG-powered 24,000 TEU ultra-large container ships ordered by German shipping giant Hapag-Lloyd from DSME in December 2020. The vessel is scheduled for delivery on April 30, 2023, and will become the world's first ultra-large container ship to use high-manganese steel LNG fuel tanks.

This type of container ship features a groundbreaking design, installing 18,000 cubic meter Type B LNG fuel tanks made of high-manganese steel. Using this new fuel tank material can save up to 2 to 3 million US dollars per vessel.

DSME stated that the successful installation of high-manganese steel LNG fuel tanks on a dual-fuel ultra-large container ship this time is also a global first. This type of high-manganese steel LNG tank is a rectangular tank, installed inside the cargo hold of the 24,000 TEU container ship, which differs from the spherical LNG tanks commonly used in currently built LNG-powered vessels. Spherical LNG tanks, due to their exposed installation method, have a large wind resistance area and are susceptible to external factors like weather, while rectangular tanks have the advantages of reducing liquid sloshing during ship navigation and having no shape limitations.

Large LNG fuel tanks are core equipment for eco-friendly fuel-powered ships and the entire LNG industry chain. They have extremely stringent technical standards and are expensive, accounting for about 30% of the total power system cost of an LNG carrier. LNG is typically stored and transported under ultra-low temperatures of -163℃. Previously, nickel alloy steel (9% Ni), aluminum alloy, and stainless steel were mainly used as the primary materials for LNG cargo tanks and fuel tanks. Among these, 9% nickel steel is currently the most widely used steel type in LNG tank manufacturing. However, the drawbacks of these materials include higher prices, complex processing procedures, and lower strength, which have limited their application. Additionally, if the expensive nickel content in the product is high, the product cost will significantly increase.

High-manganese steel refers to alloy steel with a manganese content as high as 11-14%. Global manganese resources are abundant, and the price of metallic manganese in the international raw material market fluctuates little, offering a stable advantage in terms of supply and demand. The price of high-manganese steel is also more competitive than 9% nickel steel. It can maintain ideal performance not only under ultra-low temperatures of -196 degrees Celsius but also boasts high strength and strong wear resistance. Therefore, high-manganese steel has always attracted significant attention as a new generation material for LNG fuel tanks, leading major shipyards and steel companies worldwide to engage in fierce competition to capture the high-manganese steel market.

According to International Shipping News, DSME and POSCO have jointly developed and engineered the Korean-type high-manganese steel LNG fuel tank technology over 10 years of collaborative R&D and engineering verification. On June 16 this year, DSME and POSCO held a loading ceremony for installing high-manganese steel LNG fuel tanks on LNG-powered VLCCs, successfully loading them onto two LNG-powered VLCCs built for Turkish shipowner Advantage Tankers. On October 13, these two LNG-powered VLCCs had their naming ceremony and are scheduled for delivery soon. This also marks the world's first VLCC equipped with Korean-developed high-manganese steel LNG fuel tanks, setting a milestone for the application of high-manganese steel in LNG fuel tanks.

Previously, the only vessel using POSCO's high-manganese steel LNG fuel tanks was the 50,000 DWT bulk carrier 'Green Iris,' delivered by Hyundai Mipo Dockyard in 2018 for POSCO. This vessel utilized a Type C LNG fuel tank made of austenitic high-manganese steel, specifically designed by POSCO for cryogenic LNG and liquefied gas storage, with a storage capacity of 500 cubic meters.

South Korean industry insiders state that the high-manganese steel fuel tank manufacturing technology applied this time is purely a domestic Korean technology, making it even more valuable. A large number of vessels ordered by global shipping companies between 2004 and 2007 have aged. Simultaneously, due to strengthened port entry standards for ships in major global ports and the introduction of carbon dioxide emission reduction policies, many of these aging vessels will be converted to LNG-powered ships, thus significantly increasing the demand for LNG tanks. In the future, through the mass production of high-manganese steel, South Korea will not only ensure price competitiveness in this field but also potentially achieve self-reliance in LNG cargo tank manufacturing technology.

For the South Korean shipbuilding industry, choosing POSCO's high-manganese steel LNG fuel tanks can also save on patent technology fees paid to overseas engineering companies. Until now, most LNG-powered vessels built by South Korean shipyards have used membrane-type fuel tanks from the French engineering company GTT, requiring license fees to be paid to GTT for their use.

A DSME official stated, 'By successfully installing high-manganese steel LNG fuel tanks on dual-fuel container ships, among other measures, the company will comply with increasingly stringent international maritime environmental regulations and lead the global eco-friendly shipbuilding market.'