Temperature differences between the top and the base of pipelines can, in specific circumstances, drive severe corrosion due to condensed fluids at the top-of-the-line. Here, we measure corrosion at the top-of-the-line in the condensate phase and, simultaneously, in the immersed phase at the bottom-of-the-line using an electrochemical approach. With CO₂-saturated chloride brine, corrosion at the top-of-the-line increased with fluid temperature (due to increased condensation rates), whereas at the bottom-of-the-line, the corrosion rate decreased (due to ferrous carbonate precipitation). The addition of acetic acid increased the corrosion rate at both top and bottom of the line, with any ferrous carbonate films being removed by dissolution. The addition of methyl diethanolamine (MDEA) reduced corrosion rates significantly because of the increased pH in both the condensate at the top-of-the-line and under immersion at the bottom-of-the-line, reducing the solubility of FeCO₃. Overall, the addition of acetic acid was confirmed to damage and remove protective FeCO₃ films. However, continuous films were not re-established after MDEA additions, rather porous and generally unprotective films were formed.

中文翻译：

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在乙酸 (I) 存在下减轻顶部和底部 CO2 腐蚀：使用甲基二乙醇胺控制 pH

在特定情况下，管道顶部和底部之间的温差会因管道顶部的冷凝流体而导致严重腐蚀。在这里，我们使用电化学方法测量冷凝相顶部的腐蚀，同时测量底部浸没相的腐蚀。含 CO ₂- 饱和氯化物盐水，管线顶部的腐蚀随流体温度增加（由于冷凝速率增加），而在管线底部，腐蚀速率降低（由于碳酸亚铁沉淀）。乙酸的加入增加了管线顶部和底部的腐蚀速率，任何碳酸亚铁膜都通过溶解去除。甲基二乙醇胺 (MDEA) 的添加显着降低了腐蚀速率，因为在生产线顶部的冷凝液和在生产线底部的浸没下的 pH 值均增加，从而降低了 FeCO ₃的溶解度。总体而言，已确认添加乙酸会损坏并去除保护性 FeCO ₃电影。然而，在加入 MDEA 后，没有重新建立连续的薄膜，而是形成了多孔且通常无保护的薄膜。