CO₂ corrosion is one of the important threats to the safe operation of oil and gas pipelines. Generally, the pitting
often has a greater depth than that of the uniform corrosion and it is likely to be concealed, bringing about particularly
serious hazards. In order to study the ion concentration distribution within the corrosion pits and verify the existing
corrosion prediction models, the relative integral intensity was defined based on the characteristic peak of the bicarbonate
in Raman spectroscopy and that of the background solution water with the internal standard method, and the quantitative
relationship between the relative integrated intensity and the bicarbonate molar concentration was established in the
range of 0.04-0.6 mol/L. Meanwhile, a set of flow cell system based on the in-situ laser Raman spectroscopy was designed,
and the bicarbonate molar concentration was determined at different depths of artificial pits on the X65 pipeline steel in the
flow environment. The experimental results show that: the bicarbonate molar concentration in the pit decreases gradually
within 500 μm from the pit bottom to approach the bulk solution concentration as the distance increases, and it is basically
constant when the distance is greater than 500 μm. The experimental method for determining the distribution of bicarbonate
molar concentration in the pits could provide important reference for the development of pitting theory and the verification of
corrosion calculation models. (8 Figures, 2 Tables, 28 References)
CO₂ 腐蚀是油气管道安全运行的重要威胁之一，其中点蚀的深度往往大于均匀腐蚀的深度，隐
蔽性强，危害尤为突出。为研究点蚀坑内的离子浓度分布，验证现有腐蚀预测模型，采用内标法将碳
酸氢根在拉曼光谱中的特征峰与本底溶液水的特征峰组成相对积分强度，在 0.04~0.6 mol/L 范围
内建立了相对积分强度与碳酸氢根体积摩尔浓度的定量关系。设计了一套基于原位激光拉曼光谱
技术的流动池系统，在流动环境中对 X65 管线钢模拟点蚀坑不同深度的碳酸氢根体积摩尔浓度进
行了测定。实验结果表明，在距离坑底 500 μm 范围内，点蚀坑内的碳酸氢根体积摩尔浓度随距离
增加逐渐减小至接近体相溶液浓度；当距离大于 500 μm 后，点蚀坑内的碳酸氢根体积摩尔浓度基
本保持不变。新提出的点蚀坑内碳酸氢根体积摩尔浓度分布的实验测定方法，可为点蚀理论的发展
及腐蚀计算模型的验证提供重要参考。（图 8，表 2，参 28）
CORE (COnnecting REpositories)
CORE (COnnecting REpositories)