乙二醇对X65钢在CO_2饱和的3.5%NaCl溶液中腐蚀行为的影响研究

Effect of Ethylene Glycol on Corrosion Behavior of X65 Mild Steel in CO_2-saturated 3.5%NaCl Solution

采用接触角、pH值和粘度测量等方法研究了40%(质量分数)乙二醇对CO_2饱和的3.5%(质量分数)NaCl溶液及其凝结液性质的影响,采用失重、电化学和扫描电镜等方法研究了40%乙二醇对X65钢管道顶部气相和管道底部液相腐蚀行为的影响。结果表明:在常压、35℃条件下,40%乙二醇增加了CO_2饱和的3.5%NaCl溶液及凝结液与X65钢表面的接触角、pH值及粘度;在3.5%NaCl溶液和3.5%NaCl+40%乙二醇溶液中,管道顶部的凝结液pH值均明显低于管道底部溶液;40%乙二醇加速了液相腐蚀产物膜的形成,降低了X65钢管道底部的均匀腐蚀速率,促进了管道底部发生小孔腐蚀;乙二醇对X65钢管道顶部的均匀腐蚀速率未造成明显影响,但加速了小孔腐蚀的发生。

The effect of 40%（mass fraction） ethylene glycol on the performance of CO2saturated3.5%（mass fraction） NaCl solution and relevant condensates was assessed by measurements of contact angle, pH and viscosity. Effect of 40% ethylene glycol on both top of line corrosion and bottom of line corrosion for X65 mild steel pipeline was investigated by means of weight loss, electrochemical method and scanning electron microscopy（SEM）. Results indicated that contact angle, pH and viscosity of 3.5%NaCl solution saturated by CO2 and relevant condensates were increased due to the incorporation of 40% ethylene glycol at 35 ℃ and 1 atm. In the presence of solution of 3.5%NaCl or 3.5%NaCl＋40% ethylene glycol, the pH value of the condensates formed on the top of line was lower than that on the bottom of pipeline. Due to the addition of 40% ethylene glycol to 3.5% NaCl solution, the deposition of corrosion products and pitting corrosion were accelerated, while the general corrosion rate of the bottom of pipeline was decreased. In fact, the general corrosion rate of the top of line for X65 mild steel pipeline was not obviously affected by 40% ethylene glycol, but the pitting corrosion was speeded up.