Abstract: The effects of pH, temperature and H₂S concentration on hydrogen permeation current and corrosion rate of Q235A carbon steel in weakly acidic medium were studied with the potentiostatic anodic polarization and mass loss methods. The relationship between hydrogen permeation current density and corrosion rate was investigated, aiming at using the hydrogen flux method in online non-intrusive corrosion monitoring of oil pipelines. Increasing acidity and temperature could boost hydrogen permeation current and corrosion rate of Q235A steel in the corrosive solutions, with a good linear relationship between them. The corrosion rate of Q235A steel increased initially and then decreased slightly with increasing concentration of H₂S. Meanwhile, hydrogen permeation current also increased at first and then stabilized. When the concentration of H₂S was 5-200 mg·L^-1, there was a quadratic function between corrosion rate and hydrogen permeation current. Based on inner corrosion monitoring of an experimental pipe by a self-made hydrogenermeation flux probe, the thick pipe wall could decrease the sensitivity of hydrogen permeation current. However, by the help of step potentiostatic polarization, hydrogen permeation flux was found to be linearly related to the corrosion rate of Q235A steel measured by mass loss, indicating that the hydrogen permeation flux could be applicable for the non-intrusive inner corrosion monitoring of thick oil pipelines.

Key words: corrosion, electrochemistry, petroleum, hydrogen permeation

摘要： 通过恒电位阳极极化和失重法考察了不同pH、温度和H₂S浓度下Q235A钢在弱酸性介质中的氢渗透电流密度与腐蚀速率的变化情况，着重探讨了各影响因素下氢渗透电流与失重腐蚀速率之间的相关性，为氢通量技术用于油气管道非侵入式腐蚀监测提供依据。研究发现：随着pH降低或介质温度升高，Q235A钢的腐蚀速率与氢渗透电流均逐步增大，且二者之间具有良好的线性相关性。随着H₂S浓度增加，Q235A钢的腐蚀速率呈现先增大后降低的趋势，但氢渗透电流则先增大而后趋于稳定；当H₂S浓度在5～200 mg·L^-1范围内，腐蚀速率与氢电流符合二阶多项式函数关系。通过自制的氢通量探针监测实验管道内腐蚀时，发现过厚的管壁降低了氢电流测量灵敏度，但采用恒电位阶跃法得到的氢渗透电量（氢通量）则与失重腐蚀速率之间具有良好相关性，表明渗氢电量法可用于测量油气管道的内腐蚀速率。

关键词: 腐蚀, 电化学, 石油, 氢渗透