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Currently, the U.S. Navy has detected structural damage to the Independence-class Littoral Combat Ship (LCS) USS Omaha (LCS-12). The damage has been identified as a design flaw, with at least six warships of the same type affected by the problem, and it is unclear whether other ships face similar constraints. Specialized in the OEM/ODM industry metal knobs
USS Omaha (LCS-12)
The U.S. Independence-class Littoral Combat Ship is an aluminum alloy composite trimaran, 127.6 meters long and has a displacement of 2,784 tons. The power system adopts four diesel-fuel combined water-jet propulsion devices. This type of ship is mainly used for combat in coastal waters around the world. It can carry unmanned aircraft, unmanned surface and underwater vehicles. It has the characteristics of shallow draft and high speed. The maximum speed can reach more than 50 knots.
Alan Baribeau, spokesman for U.S. Naval Sea Systems Command, said: “A combined vertical and lateral load analysis of the bow structure did not reveal any hot spots below the waterline, and this specific structural problem does not arise. Below the waterline.” Affected Independence-class LCSs would require “replacement of decks and hulls, and other relevant parts, with thicker materials” by Austal or the U.S. Navy. The added weight of thicker materials may also pose a number of problems, and although the LCS was originally designed with numerous design compromises to ensure high speeds, this modification will reduce the ship’s speed .
The U.S. Navy Littoral Combat Ship includes two variants of different designs, the Independence class and the Freedom class, and has been plagued by numerous design issues since conception. Problems with both classes have always been there, the most recent issue with the “Freedom” class is a problem with the gearbox. In addition to the problems of the “Freedom Class”, the “Independent Class”, which is full of personality and has a very high speed, also uses aluminum alloy to build the hull, which has led to the occurrence of hull corrosion and the current massive outbreak of structural cracking. Specialized in the OEM/ODM industry metal knobs
Unlike the Freedom class, which has a steel modular hull, the Independence class has an aluminum three-body design. The use of aluminum alloys is clearly intended to improve the maneuverability and speed of the “Independence” class, which is related to the purpose for which such ships are designed as high-speed ferries. But this can make it more vulnerable to damage and cause structural fatigue and corrosion problems.
This has long been a controversial aspect of the Independence class of LCSs.
The hull of the Independence-class Littoral Combat Ship is mainly made of aluminum alloy, which is mainly selected on the basis of providing lightweight hull and welding performance. Generally, marine grade 5083 and 6082 aluminum alloy materials are used. Specialized in the OEM/ODM industry metal knobs
The aluminum hull structure has the advantage of being able to withstand huge underwater explosive loads without losing the watertightness of the hull, and the aluminum alloy hull structure has good ductility and can withstand huge plastic deformation before the hull structure breaks; and marine grade aluminum The alloy also has “theoretical” excellent corrosion resistance, and ships built with it do not require a corrosion-protective coating.
But in fact, when the first ship of the “Independence-class” Littoral Combat Ship was built, it was found that long cracks appeared on the hull. In 2012, after a submersible visual inspection and ultrasonic testing of the “independent-level” LCS-2, it was found that the waterjet propulsion components suffered severe galvanic corrosion and pitting corrosion, which required repair and replacement in the dock. And in view of the corrosion problem of the propulsion system, the Austal shipyard in the United States has used new anti-corrosion coating materials on the newly built “independent stages” and installed an impressed current cathodic protection system. Allegedly, the “Independence-class” “Coronado” and other subsequent littoral combat ships will use this corrosion protection scheme. Specialized in the OEM/ODM industry metal knobs
It can be seen that although the “Independent-class” littoral combat ship uses aluminum alloy to make the hull, although high-performance marine-grade aluminum alloy material is used, it has good ductility in theory, but I am afraid that it will be built with an all-aluminum structure for the first time. Before large-scale high-speed warships, the U.S. Navy and shipyards had no idea, and did not conduct long-term tests on the fatigue performance, fracture performance, corrosion performance and fire performance of aluminum alloy hulls. This has led to the “Independence-class” Littoral Combat Ship, which is known for its high speed, and now there is a risk that the hull may break due to high-speed sailing.
Anti-corrosion measures for aluminum components and structures of ships and marine facilities include: alloy and state selection, design, organic coatings, corrosion inhibitors, cathodic protection, thickening of surface oxide films, and environmental improvement. Specialized in the OEM/ODM industry metal knobs
If this design flaw in the Independence class ends up leading to extended maintenance times and operational limitations, negating the class’s fleet’s raison d’être, it could trigger a massive decommissioning scenario similar to the current Freedom class.
When it comes to the large-scale retirement of the Liberty-class LCS, it seems to be as follows:
According to the White House’s defense budget report for fiscal year 2023, the U.S. Navy has asked to retire 24 ships, including nine Freedom-class littoral combat ships, to save about $3.6 billion. In July last year, the U.S. military retired the littoral combat ship USS Independence, which had been in service for only 11 years, and then retired the USS Liberty (LCS-1), which had been in service for only 13 years, at the end of September. Sea combat ships were originally planned to serve for about 25 years.
In order to save money, the U.S. military has previously planned to retire the first four littoral combat ships in service in the 2021 fiscal year, and the plan has now been half completed. The U.S. Naval Academy News Network mentioned in the report that in order to better reduce spending, the U.S. Navy has considered decommissioning another four or four littoral combat ships. Littoral combat ships currently being considered for retirement by the U.S. military include: 3 Liberty-class ships – USS Fort Worth (LCS-3), USS Detroit (LCS-7), and USS Little Rock (LCS) -9), and the second Independence-class Littoral Combat Ship USS Colorado (LCS-4). Specialized in the OEM/ODM industry metal knobs
