高温环境下管线最小阴保电位分析

Analysis on the Minimum Cathodic Protection Potential of Pipeline Under High Temperature Environment

阴极保护是保障埋地管道腐蚀防护的关键方法之一,而阴保电位的设置受到管道温度影响。通过电化学测试、腐蚀速率计算和腐蚀形貌表征相结合,分析了NS4近中性溶液中X80钢的最小阴极保护电位。结果表明:随着阴保水平的增大,20℃时X80钢全面腐蚀速率和点蚀速率基本保持不变,表现为全面腐蚀状态;而在50℃和80℃时全面腐蚀速率和点蚀速率逐渐减小,腐蚀形态由点蚀形态转变为全面腐蚀形态。综合考虑腐蚀速率、腐蚀形态和电化学反应电位区间,在50℃时最小阴保电位为-1.0 V,80℃时为-1.1 V。

Cathodic protection is one of the key methods to ensure the corrosion prevention of buried pipeline, and the setting of cathodic protection potential is affected by the temperature of pipeline. In this paper, the minimum cathodic protection potential of X80 steel in NS4 near-neutral solution was analyzed by combining electrochemical test,corrosion rate calculation and corrosion morphology characterization. The results showed that with the increase of cathodic protection, the overall corrosion rate and pitting corrosion rate of X80 steel basically remained unchanged at 20 ℃, behaved as overall corrosion. At 50 ℃ and 80 ℃, the overall corrosion rate and pitting rate gradually decreased, and the corrosion morphology was changed from pitting corrosion to overall corrosion. Taking corrosion rate, corrosion form and cathodic potential range of electrochemical reaction into consideration, the minimum cathodic protection potential was-1.0 V at 50 ℃ and-1.1 V at 80 ℃.