The Reliability Of Watertight Longitudinal Girders Of Fuel Tanks On Aging Bulk Carriers

During the exploitation of bulk carriers, the condition of structural elements and areas depends on the type of the cargo transported, operational conditions and maintenance systems. Corrosion significantly accelerates the aging of metal plates and girders thus causing the deterioration of steel surfaces, which consequently reduces the reliability of structural elements, areas and ships in general. The damage to metal structures can impair the stability of a ship, reduce longitudinal strength, cause the ingress of water into the hull as well as environmental pollution through fuel spills from the tanks. Therefore, the paper analyzes a part of a double bottom structure based on the available wear data on watertight longitudinal girders of fuel tanks. The research included 25 bulk carriers aged between 5 and 25 with the total of 110 fuel tanks. The reliability analysis of steel plates included the total of 1920 data measured. The allowable wear of structural plate thickness that equals 20% of the original thickness value was determined by the application of the acceptance criteria that were prescribed by classification societies. The calculations of the function of failure density, failure intensity and reliability determined the time when the condition of structural elements deteriorates due to corrosion up to the levels that require extensive maintenance services.