Parametric Study and Risk Analysis of SPM Chain Line due to Fatigue and Corrosion Effect
In process of unloading on tankers, there are several obstacles, one of the obstacles is breaking of SPM mooring line when the unloading process is in progress. This can endanger the safety of crew and ship buildings due to colliding with other floating structures. This factor is the reason for need analysis to determine the value of strength structure on the mooring line, so that operability and safety of the mooring system can be maintained. Therefore, there is a need for a risk analysis study on SPM chain line structure which is carried out using the FTA-FMEA method, where risk analysis of chain line structure in this study is caused by fatigue under stress loads and dimensional reduction due to corrosion effect. Results showed that variations in diameter SPM affect fatigue in mooring line series where larger diameter SPM and higher significant wave load in the operational environment, the greater nominal stress and deformation in each loading and environmental conditions. Results of age on chain line structure still meet safety standards. Mitigation measures on critical risk indicate that interpretation of minimum cut set is a failure in form of a broken chain line in SPM mooring line, minimum cut set for SPM chain line component which has a critical risk of 3.3%. Mitigation step in risk analysis that should be taken to reduce causes described by minimum cut set is to implement periodic inspections that are more stringent in frequency on mooring line series, besides that it is necessary to apply preventive maintenance which previously only applied corrective maintenance.
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