深海管道的冲刷腐蚀与防护研究

This project is aimed at the unsolved problems of deep-sea pipeline: The perforation of deep-sea tubular structure, such as elbow and tee, caused by erosion-corrosion of internal multiphase. The deep-sea pipe has a complicated bearing state under the action of high temperature difference, extra-high external pressure and internal operating pressure. The mechanical mechanism is hardly considered in the study of erosion-corrosion test. Erosion-corrosion may lead to stress corrosion cracking of deep-sea pipelines. Due to the neglect of mechanical mechanism, the existing studies underestimated the damage process of deep-sea pipeline caused by erosion-corrosion. This project focus on the erosion-corrosion of stressed pipe, combining with the theory of mechanics and experimental method to reveal the damage mechanism of deep-sea pipeline under different load and erosion environment, and reveal the damage evolution law, to explore the critical failure factors and establish the mechanical model of damage evolution. The mechanical model is verified by numerical simulation and experiment test. Sensitivity analysis of mechanical factors, material properties and environmental parameters is carried out. Based on the key issue, a new protective method for stressed-erosion-corrosion is proposed to ensure the safe operation of the deep-sea pipeline.

本课题针对深海管道亟待解决的难题：内部多相流冲刷腐蚀导致弯管、三通等深海管道结构穿孔失效。深海管道在内外高温差、超高外压和内部操作压力作用下受力复杂。已有的冲刷腐蚀试验研究几乎未考虑力学机理。冲刷腐蚀可能导致深海管道发生应力腐蚀开裂，已有研究由于忽略力学机理，低估了深海管道冲刷腐蚀的损伤过程。本研究从受力管道的冲刷腐蚀入手，应用力学理论与试验相结合的方法，揭示深海管道在不同荷载和侵蚀环境下的损伤机理及其规律，探索关键失效因素，建立损伤演化力学模型。并结合数值模拟和试验对力学模型进行验证。对力学因素、材料属性，环境参数进行敏感性分析。针对关键问题，提出耐应力冲刷腐蚀的新防护方法，以保证深海管道的安全运营。

到目前为止，关于受力构件的应力冲刷腐蚀研究几乎一片空白，国内外学者尚未建立受力构件的冲刷腐蚀力学模型。本课题针对深海管道亟待解决的难题：内部多相流冲刷腐蚀导致弯管、三通等深海管道结构穿孔失效。深海管道在内外高温差、超高外压和内部操作压力作用下受力复杂。冲刷腐蚀可能导致深海管道发生应力腐蚀开裂，已有研究由于忽略力学机理，低估了深海管道冲刷腐蚀的损伤过程。本研究从受力管道的冲刷腐蚀入手，应用力学理论与试验相结合的方法，揭示深海管道在不同荷载和侵蚀环境下的损伤机理及其规律，探索关键失效因素，建立损伤演化力学模型。并结合数值模拟和试验对力学模型进行验证。对力学因素、材料属性，环境参数进行敏感性分析。针对关键问题，提出耐应力冲刷腐蚀的新防护方法，以保证深海管道的安全运营。研究表明最大冲蚀速率随着流速增大呈指数递增趋势。研究发现，施加应力越大，冲蚀速率增长越快，这进一步证实了荷载效应对冲蚀的促进作用。此外，温度升高使CrFeCoNi熔覆层的腐蚀抗性降低。CrFeCoNi熔覆层的相角图在所有温度下都具有较宽的峰值相角，且峰值相角接近90°。制备涂层的熔覆层在不同温度条件下抗腐蚀性能的差异是由于在熔覆层表面形成的钝化膜的稳定性不同。