天然气管道内腐蚀直接评价方法的改进

An improvement on direct assessment method for internal corrosion of natural gas pipeline

天然气管道内腐蚀直接评价是一种重要的管道内腐蚀评估手段,为了提高内腐蚀直接评价方法的适用性与准确性,采用电化学测试与数值模拟方法研究CO_(2)电化学腐蚀及管内颗粒冲蚀对管道内腐蚀的影响,并分析管道倾角与持液率对电化学腐蚀的影响。结果表明:天然气管道中电化学腐蚀对管道内腐蚀的影响远大于颗粒冲蚀的影响,颗粒冲刷作用可加速电化学腐蚀;管道倾角越大,持液率越高,管道内腐蚀越严重;在管道倾角较小、上坡段管道较长的位置易发生内腐蚀。在此基础上,提出了一种新的天然气管道内腐蚀直接评价方法,并应用于盘锦某天然气管道。评价结果表明:与原有管道内腐蚀评价方法相比,改进方法能更准确地判别管道积液位置,比较各积液位置的腐蚀风险,因而为天然气管道内腐蚀评估提供更有力的技术支持。

Direct assessment for internal corrosion of gas pipeline is an important method to assess the internal corrosion of pipelines. In order to improve the applicability and accuracy of direct assessment method for internal corrosion, the influence of CO_(2) electrochemical corrosion and particle erosion on the internal corrosion of pipeline was studied through electrochemical testing and numerical simulation. At the same time, the influence of pipeline inclination and liquid holdup on electrochemical corrosion was also analyzed. The research results show that: The influence of electrochemical corrosion on the internal corrosion of the gas pipeline is much greater than that of particle erosion, but the particle erosion can accelerate the electrochemical corrosion. Specifically, the greater the inclination of the pipeline, the higher the liquid holdup,and the more serious the corrosion is. In addition, the long uphill section of pipeline with a smaller inclination is prone to corrosion. Thereby, a new direct assessment method for internal corrosion of natural gas pipelines was proposed and applied to a natural gas pipeline in Panjin. The assessment results show that, compared with the original method, this improved method can more accurately identify the location of water accumulation in the pipeline, compare the corrosion risk of each place of water accumulation, and thus provide new theory and technical support for the assessment of internal corrosion in natural gas pipelines.