Submitted by Brush Research Manufacturing Co. Inc.
The Flex-Hone Tool, characterized by the small, abrasive globules that are permanently mounted to flexible filaments, has long been used for everything from automated metal finishing to maintenance and repair operations. Now the Flex-Hone can add one more claim to its resume: playing a small, but important, role in one of the largest engineering feats in marine history—the raising of the shipwrecked Costa Concordia.
The 952 foot long, 17 deck high cruise ship the Costa Concordia was wrecked off the coast of Isola del Giglio in Italy on Jan. 13, 2012. It was declared a total loss and 32 people lost their lives. The ship eventually settled on its starboard side in shallow waters with half the boat still submerged.
Concerned about a potential environmental disaster that could result from the large quantity of fuel and oil remaining in the ship’s tanks, not to mention a large quantity of rotting food and other health concerns, a salvage effort to move the ship to a suitable port where it could be properly dismantled was commissioned. The effort, awarded to the American salvaging firm Titan Salvage and Italian underwater construction firm Micoperi, ultimately cost an estimated two billion dollars and took several years.
The endeavor to raise the Costa Concordia enough to move it, involved a series of complex steps, several of which had not been attempted in decades.
The endeavor to raise the Costa Concordia—a 952-foot-long, 17-deck-high cruise ship wrecked off the coast of Isola del Giglio in Italy—involved a series of complex steps, several of which had not been attempted in decades. Images courtesy Brush Research Manufacturing.
The first step was to secure the hull to the land using steel cables to prevent the ship from slipping into deeper water. A horizontal underwater platform was then built just below the ship’s position to hold the ship once it was raised.
Hollow, watertight tanks, called sponsons, were then attached to the exposed port side of the ship. When sponsons are flooded with seawater, they exert a downward pull on that side of the ship. With the assistance of winches attached to the platform, a process called parbuckling, the ship was pulled into an upright position on top of the underwater platform.
Once the ship was vertical, water-filled sponsons were attached to the starboard side as well. Then, both sponsons were emptied of water to create the required buoyancy to raise the ship enough so it could be towed to port.
The challenge for Micoperi, a leading offshore contractor that provides subsea solutions for the offshore oil and gas industry worldwide, was to find a way to attach 15 massive steel sponsons to each side of the ship. The 30 sponsons weighed 11,500 tons, combined.
The plan was to weld the steel sponsons to the hull of the ship, but also to join them together to form “one single, robust, stable body,” similar to one integral floating chamber. For this, male and female “joints” were attached to each container so they could be connected to each other. A tubular frame would then be run through each of these joints to attach all the containers together. Hydraulic pistons within the tubes would pressurize the system to further hold the tanks together as one unit.
The plan to raise the Costa Concordia was to weld steel sponsons, seen here, to the hull of the ship and join them together to form "one single, robust, stable body," similar to one integral floating chamber.
Since it was not possible to introduce a single tube more than 100 meters in length, the engineers decided the best solution was to start with a small section of tube approximately 2 meters long and push it through the first male/female joint. Then another section of tube would be welded to the first, which would be pushed through the joints a little further, and another section welded, and so on.
This operation would be repeated for the port side, once the ship was raised enough vertically from the initial parbuckling procedure.
To remove the excess material from the welds as they were created – both on the interior and exterior of the tubing – Micoperi required a tool that could remove the excess material and worked on an industrial hand-held drill.
For assistance, Micoperi contacted Vogel, an Italian distributor of machine tools, industrial equipment and metals. Among its offerings is the Flex-Hone from Los Angeles-based Brush Research Manufacturing.
The Flex-Hone is available in many sizes, 11 abrasive types and eight grits. It works well when hand-held because the design is automatically self-centering. Using the tool, parts such as carbide bushings, bore sleeves, hydraulic and pneumatic cylinders, and other cylindrical cavities can be surface finished on the production line or resurfaced in the field using a relatively inexpensive tool that requires little set-up time.
“Micoperi called us and we discussed whether the Flex-Hone Tool could be a solution for its problems,” says Sven Pilling of Vogel. “During the discussion, we determined that only the Flex-Hone was suitable. Other tools, like abrasive nylon brushes, would not guarantee enough stock removal.”
Micoperi ultimately purchased Brush Research Manufacturing’s BC 3" SC 60 and BC 3" SC 80 Flex-Hone Tools.
The Flex-Hone served another important function by smoothing the way for the hydraulic pistons that were introduced into the tubes.
No stranger to the hydraulics industry, the Flex-Hone tool is already widely used to manufacture all manner of hydraulic cylinders, pumps, jacks, and valves. Hydraulic toolmakers often used the tool to obtain the proper finish in the cylinder bore. If the hydraulic cylinder finish is too rough, U-cups and seals can wear out. If the cylinder surface is too smooth, hydraulic seals may leak.
“In order to allow a smooth movement of the pistons and in order to avoid leakages, the internal tube walls were cleaned and polished successfully with the Flex-Hone,” says Pilling.
Although the Costa Concordia project is now complete, the Flex-Hone remains a go-to tool for overhaul and repair for marine applications. The tool is used for cylinder refinishing of big bore (up to 40-inch diameter) diesel main engines of large vessels as well as smaller diesel generators. The tool can also be used for cleaning pipe bores for pipes or other cylindrical bores such as valves on some pump designs.
For more information, contact Brush Research Manufacturing, Brush Research Mfg. Co., Inc., 4642 Floral Drive, Los Angeles, CA 90022; Phone: (323) 261-2193; Fax: (323) 268-6587; email: info@brushresearch.com or visit the website: www.brushresearch.com.
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