Flex-Hone® in use during the salvage of the Costa Concordia
The Flex-Hone® tool, which is characterized by small abrasive balls permanently attached to flexible threads, has long been used for everything 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 important role in one of the greatest technical achievements in the history of shipping – the salvage of the shipwrecked Costa Concordia.
The 952-foot-long, 17-deck-high cruise ship Costa Concordia crashed off the coast of Isola del Giglio in Italy on January 13, 2012. It was declared a total loss and 32 people lost their lives. The ship finally sank on its starboard side in shallow water, with half of the ship still under water.
Concerned about a potential environmental disaster resulting from the large amounts of fuel and oil in the ship’s tanks, not to mention the large amounts of rotting food and other health problems, a salvage operation was ordered to bring the ship to a suitable port where it could be properly dismantled.
The work, which was awarded to the American salvage company Titan Salvage and the Italian underwater construction company Micoperi, ultimately cost an estimated two billion dollars and took several years to complete. Raising the Costa Concordia to the point where it could be transported required a series of complex steps, some of which had not been undertaken for decades.
The attempt to salvage the Costa Concordia – a cruise ship approximately 300 meters long and 17 decks high that wrecked off the coast of Isola del Giglio in 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 to the hull of the ship, as seen here, and joining them together to form a single, robust and stable “body”, similar to an integrated flotation chamber.
The first step was to secure the hull to the land with steel cables to prevent the ship from sliding into deeper water. A horizontal underwater platform was then built directly below the ship’s position to hold the ship once it was raised.
Hollow, watertight tanks were then attached to the exposed port side of the ship. When the tanks are flooded with seawater, they exert a downward pull on this side of the ship. With the help of winches attached to the platform, the ship was pulled into an upright position on the underwater platform.
As soon as the ship was upright, pylons filled with water were also attached to the starboard side. Both beams were then emptied with water to create the necessary buoyancy to raise the ship sufficiently to be towed into port.
The challenge for Micoperi, a leading offshore company providing subsea 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 vessel. The 30 tanks weighed a total of 11,500 tons.
The plan was to weld the steel tanks to the hull and join them together to form a single, robust and stable “body”, similar to an integrated floating chamber. For this purpose, male and female “joints” were attached to each container so that they could be connected to each other. A tubular frame would then pass through each of these joints to connect all the containers together. Hydraulic pistons in the pipes pressurize the system to hold the containers together as a single unit.
Since it was not possible to insert a single pipe more than 100 meters long, the engineers decided that the best solution was to start with a small section of pipe about 2 meters long and push it through the first male/female connection. Then another pipe section was welded to the first, which was pushed a little further through the socket, then another section was welded, and so on. This process was repeated on the port side as soon as the ship had been raised sufficiently vertically after the first parbuckling procedure.
To remove the excess material from the weld seams – both on the inside and outside of the pipes – Micoperi needed a tool to remove the excess material and worked with an industrial hand drill. Micoperi turned to an Italian distributor of machine tools, industrial equipment and metals for support. His range of products included Flex-Hone® tools.
The Flex-Hone® tool is available in many sizes, eleven abrasive types and eight grit sizes. It is easy to hold in the hand as the design is automatically self-centering. The tool can be used to surface finish parts such as carbide bushings, bore sleeves, hydraulic and pneumatic cylinders and other cylindrical cavities on the production line or rework them 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 eventually purchased the Flex-Hone® tools BC 3″ SC 60 and BC 3″ SC 80. The Flex-Hone® tool fulfilled another important function by paving the way for the hydraulic pistons to be inserted into the pipes. The Flex-Hone® tool is not unknown in the hydraulics industry and is already widely used to manufacture all types of hydraulic cylinders, pumps, lifters and valves. Hydraulic tool manufacturers often used the tool to correctly machine the cylinder bore. If the surface of the hydraulic cylinder is too rough, U-seals and seals can wear out. If the cylinder surface is too smooth, hydraulic seals can leak.
“To enable the pistons to move smoothly 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 ship applications. The tool is used for cylinder repair of diesel engines with large bores (up to 40 inches in diameter) on large ships as well as smaller diesel generators and can also be used to clean pipe bores or other cylindrical bores on some pump designs.