Raising the Costa Concordia A tool that has long been used for everything from automated metal finishing to maintenance and repair operations can now add one more claim to its résumé: 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-ft-long, 17-deck-high cruise ship the Costa Concordia was wrecked 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 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 $2 billion 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 — Fig. 1. 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, waterfilled 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, an 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 — Fig. 2. For this, male and female “joints” were attached to each contain- TECHNOLOGY 34 WELDING JOURNAL / NOVEMBER 2016 BY JEFF ELLIOTT An abrasive tool played a small, but important, role in helping raise the capsized cruise ship Fig. 1 — The project to raise the Costa Concordia involved a series of complex steps.
Welding Journal | November 2016
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