Safety Assessment Of SZ36-1 To Terminal Seabed Pipe Cross Safety

Because of the complex of the submarine pipeline in offshore environment,it is a large challenge to insure the safety of these pipeline in use during the process of design, building,management and operation.Based on the survey of pipeline engineering data of oil submarine pipeline in SZ36-1to Sui Zhong Onshore processing terminal pipeline, the reasons for formation and types of suspending pipeline are analyzed in detail, and the hydrodynamic parameters for spanning submarine pipeline are determined. At the same time, according to the mechanism of ocean current and Jones equation, the calculating methods for the horizontal hauling force and vertical lift force are confirmed. The most dangerous spanning submarine pipeline are determined, and stability is analyzed to provide stability reference for reliability of spanning pipeline.The finite element model of spanning pipeline is built and the stress concentration factors are obtained from software solution. Considering the stress concentration factor, the local buckling failure reliability model is built, which is much more practical and realistic.Considering the maximum length of suspending as a index judging whether the resonance Occurred, the resonance reliability model is built. The maximum length of suspengding is calculated based on the analysis of different rules of vibration. The reliability degree model of the spanning submarine pipeline is built by Monte-Carlo and the reliability degree of the resonance are calculated and analyzed.Buckling failure occurs when the stress of submarine pipeline on axial force exceeds critical pressure. The overall buckling reliability model is built to calculate critical buckling pressure. The reliability degree of the overall buckling is calculated and analyzed in the way of Monte-Carlo.Based on DNV-RP-F105(2006), the fatigue reliability assessment method of the submarine span is studied in this paper, and the fatigue reliability assessment model is built. According to the Miner cumulative fatigue damage linear theory, combined S-N curve and theory of reliability analysis, the fatigue life of the span which is aroused by the current and wave forces is studied.Finally, the safety and reliability assessment system is developed, which can efficiently make an evaluation for the spanning submarine pipeline.The result of evaluation is helpful for improving the safety of the submarine pipelines.