复合管X65／316L在模拟产出水中电偶腐蚀行为研究

Gavalic corrosion behaviors of X65-316L bimetal tube in simulating production water

海洋天然气输送用复合金属管由于内层金属穿孔常发生内外层问电偶腐蚀。本文采用浸泡试验和电化学技术分析X65—316L构成电偶对在模拟产出水中电偶腐蚀行为。采用SEM观察腐蚀前后形貌变化；分析X65和316L偶接前后开路电位（OCP）和偶接电流（Icc）随时间变化，以及电化学参数变化。结果显示，X65—316L电偶对在模拟产出水中X65为阳极，316L为负极；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 always appears in the outer layer of bimetal tube applying in ocean natural gas transportation after the galvanic corrosion model is built between the outer layer and the inner layer, as soon as the corrosive production solution permeate into the space between the outer layer and the inner layer due to pitting corrosion happened in the inner layer. In this paper, galvanic corrosion is investigated through immersion experiment and electrochemical techniques. Corrosion morphology of X65-316L bimetal tube is observed through SEM before and after immersion experiment. The open circuit potential （OCP） of X65 and 316L and galvanic current （Ice） are measured during galvanic experiment. And electrochemical factors are analyzed according to dynamic polarization curves before and after X65 are connected with 316L. The results show that X65 place anodic electrode and 316L place cathodic electrode in the galvanic corrosion model. And the corrosion rate of X65 increased and that of 316L decreased when compared with that before X65 was connected with 316L. At the same time, cathodic polarized rate of 316L decreased and anodic polarized rate of 316L increased.