Flex-Hone® in Use During the Salvage of the Costa Concordia
The Flex-Hone® tool, characterized by small abrasive globules permanently attached to flexible filaments, has long been used in all areas from automated metalworking to maintenance and repair work. Now, the Flex-Hone® tool can add another milestone to its success story: it played a small but crucial role in one of the greatest engineering feats in maritime history – the salvage of the shipwrecked Costa Concordia.
The 952-foot long and 17-deck high cruise ship Costa Concordia met with disaster on January 13, 2012, off the coast of Isola del Giglio, Italy. It was declared a total loss, and 32 people lost their lives. The ship eventually sank onto its starboard side in shallow water, with half of the vessel still submerged.
Concerned about a potential environmental disaster arising from the large quantities of fuel and oil in the ship’s tanks, not to mention the vast amounts of decaying food and other health hazards, a salvage operation was commissioned to bring the ship to a suitable port where it could be properly dismantled.
The work, awarded to the American salvage company Titan Salvage and the Italian underwater construction firm Micoperi, ultimately cost an estimated two billion dollars and spanned several years. To raise the Costa Concordia sufficiently for transport, a series of complex steps were required, some of which had not been undertaken for decades.
The attempt to salvage the Costa Concordia – a cruise ship approximately 300 m long and 17 decks high, which ran aground off the coast of Isola del Giglio, Italy – involved a series of complex steps, some of which had not been undertaken for decades. Image courtesy of Brush Research Manufacturing.
The plan to raise the Costa Concordia involved welding steel tanks, as seen here, to the ship’s hull and assembling them into a single, robust, and stable “body,” similar to an integrated buoyancy chamber.
The first step involved securing the ship’s hull to the land with steel cables to prevent the vessel from sliding into deeper water. Subsequently, a horizontal underwater platform was constructed directly beneath the ship’s position to support it once it was raised.
Hollow, watertight tanks were then attached to the exposed port side of the ship. When these tanks were flooded with seawater, they exerted a downward pull on this side of the vessel. Using winches secured to the platform, the ship was pulled into an upright position onto the underwater platform.
Once the ship was upright, water-filled pylons were also attached to the starboard side. Subsequently, both sets of tanks were emptied of water to generate the necessary buoyancy, allowing the ship to be raised sufficiently for towing to port.
The challenge for Micoperi, a leading offshore company providing underwater solutions for the offshore oil and gas industry worldwide, was to find a way to attach 15 massive steel tanks to each side of the ship. The 30 tanks collectively weighed 11,500 tons.
The plan involved welding the steel tanks to the ship’s hull and assembling them into a single, robust, and stable “body,” similar to an integrated buoyancy chamber. For this purpose, male and female “joints” were attached to each container so they could be interconnected. A pipe frame would then be passed through each of these joints to connect all the containers. Hydraulic pistons within the pipes pressurized the system to hold the containers together as a single unit.
Since it was not possible to insert a single pipe longer than 100 meters, the engineers decided that the best solution was to start with a small pipe section, approximately 2 meters in length, and push it through the first male/female connection. Then, another pipe section was welded to the first, pushed a bit further through the sleeve, then another section was welded, and so on. This process was repeated on the port side once the ship had been sufficiently raised vertically after the initial parbuckling procedure.
To remove excess material from the welds – both on the inside and outside of the pipes – Micoperi required a tool that could remove the excess material and operate with an industrial hand drill. Micoperi approached an Italian distributor of machine tools, industrial equipment, and metals for assistance. Among its offerings were Flex-Hone® tools.
The Flex-Hone® tool is available in many sizes, eleven abrasive types, and eight grits. It is easy to handle due to its self-centering design. The tool can be used to surface finish or re-finish parts such as carbide bushings, bore sleeves, hydraulic and pneumatic cylinders, and other cylindrical cavities on the production line or on-site. “Micoperi called us, and we discussed whether the Flex-Hone® tool could be a solution to their problems,” says Sven Pilling from the Italian distributor. “During the conversation, we realized that only Flex-Hone® was suitable. Other tools, such as abrasive nylon brushes, would not ensure sufficient material removal.”
Micoperi ultimately purchased the Flex-Hone® tools BC 3″ SC 60 and BC 3″ SC 80. The Flex-Hone® tool served another important function by paving the way for the hydraulic pistons that were inserted into the pipes. The Flex-Hone® tool is well-known in the hydraulics industry and is already widely used for manufacturing all types of hydraulic cylinders, pumps, lifts, and valves. Manufacturers of hydraulic tools frequently used the tool to correctly machine the cylinder bore. If the surface of the hydraulic cylinder is too rough, U-seals and gaskets can wear out. If the cylinder surface is too smooth, hydraulic seals can leak.
“To enable smooth movement of the pistons and to prevent leaks, the inner walls of the pipes were successfully cleaned and polished with the Flex-Hone®,” says Pilling. Although the Costa Concordia project has long been completed, the Flex-Hone® remains a preferred tool for the overhaul and repair of marine applications. The tool is used for cylinder repair of large-bore diesel engines (up to 40 inches in diameter) on large vessels, as well as for smaller diesel generators, and can also be used for cleaning pipe bores or other cylindrical bores in some pump designs.