ABSTRACT Corrosion under insulation (CUI) is a form of corrosion that occurs when moisture ingress through insulation and comes into contact with underlying metallic equipment. The rate of CUI depends on the ionic conductivity of the insulation, which, in turn, is related to the moisture distribution and metal ion concentration within the moist insulation. Metal ions are introduced into the moist insulation by metal corrosion and also from leaching from the insulation itself. These metal ions cause an increase in ionic conductivity through the moist insulation, thus influencing CUI. It was also observed that contact of steel with moist insulation, intrinsically increases its corrosion due to the formation of differential aeration cells resulting from variable oxygen diffusion arising from the non-homogenous packing of the insulation. Herein, the effect of such dissolved ions on CUI was studied. It was observed that the rate of CUI increases with time due to the release of metallic ions into the moist insulation.

中文翻译：

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绝缘下低碳钢的腐蚀——溶解金属离子的影响

摘要 绝缘层下腐蚀 (CUI) 是一种腐蚀形式，当湿气通过绝缘层进入并与下面的金属设备接触时发生。CUI 的速率取决于绝缘材料的离子电导率，而后者又与潮湿绝缘材料内的水分分布和金属离子浓度有关。金属离子通过金属腐蚀以及从绝缘体本身浸出而被引入潮湿绝缘体。这些金属离子通过潮湿的绝缘层导致离子电导率增加，从而影响 CUI。还观察到钢与潮湿绝缘体的接触，由于绝缘体的非均匀填充引起的可变氧扩散导致差异曝气单元的形成而本质上增加了其腐蚀。在此处，研究了这种溶解离子对 CUI 的影响。据观察，由于金属离子释放到潮湿绝缘体中，CUI 的速率随时间增加。