海洋天然气输送用复合金属管内外层因内层金属输送介质渗漏将构建电偶对, 加速外层金属腐蚀。本工作采用浸泡试验和电化学技术分析X65-316L电偶对在模拟产出水中的电偶腐蚀行为。采用SEM观察电偶对金属腐蚀前后形貌变化; 分析X65和316L偶接前后开路电位(OCP)和偶接电流密度(Jcc)随时间的变化曲线, 以及其对电化学参数的影响。结果显示, X65-316L电偶对在模拟产出水中X65为阳极, 316L为阴极; 与偶接前相比, X65腐蚀速率增加, 316L腐蚀速率下降, 同时X65阴极极化率减小, 316L阳极极化率增加。

Galvanic corrosion appears in the outer layer of bimetal tube for ocean natural gas transportation after the gavalic corrosion model is built between the outer layer and the inner layer. The corrosive production solution permeates into the space between the outer layer and the inner layer due to perforation of inner layer. In this work, galvanic corrosion was investigated by immersion test and electrochemical measurements. Corrosion morphology of X65-316L bimetal tube was observed by SEM before and after immersion. The open circuit potential (OCP) of X65 and 316L and the gavalic current density (Jcc) were measured during galvanic experiment. Electrochemical parameters were analyzed according to dynamic polarization curves before and after connection of X65 with 316L. The results show that X65 acted as an anodic electrode and 316L was cathodic electrode in the gavalic corrosion couple. The corrosion rate of X65 increased and that of 316L decreased when compared with that before their connection. At the same time, cathodic polarization rate of X65 decreased and anodic polarization rate of 316L increased.