Feature: Temporary Hull Repair on FPSO Stands the Test
Alan C. McClure Associates (ACMA) recently completed strength analysis of the tank bottom plating of an FPSO for a large oil company. ACMA's analysis focused primarily on the effectiveness of repairing corroded shell plating with Intelligent Engineering's Sandwich Panel System (SPS).
"Utilizing our advanced Finite Element Analysis (FEA) capabilities, we examined the vessel hull to evaluate repair alternatives to the corroded shell plating," said principal structural engineer Peter Marucci. "We loaded the model with hydrostatic and hydrodynamic pressures that the hull would experience from still-water and wave-induced bending moments." Because it's vital to examine all material and environmental variables to predict real-time performance, ACMA evaluated multiple models to determine stresses and loads within the FPSO tank. Similar analyses can also be performed for hull structural members to determine stresses during design and later during repairs for critical and 'hot' areas that are especially important for barges, cargo ships and all marine vessels. The Sandwich Panel System (SPS), developed by Intelligent Engineering, is a technology that permits repairs without hot work inside the tank, allowing the vessel to remain in service. "Based on our modeling of the proposed repair sites, stress was shown to be significantly reduced using the sandwich paneling," Marucci explained. SPS does substantially extend the working time for the vessel and, in this case, appeared to be the best solution available until resources would allow for a more thorough repair and/or restoration.
"There are a number of tankers in service today that are experiencing structural problems in areas where a high level of corrosion has occurred," says ACMA Vice President Darrel Harvey. "Our advanced analytical capabilities and extensive shipyard experience gives ACMA a pronounced advantage in providing our clients with unbiased, third-party analysis of these kinds of challenges, as well as the ability to recommend the most cost-effective solutions."
