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阴极保护度取决于电解液与结构体接触面的外加电流密度。要使整个结构体都得到阴极保护,应使结构体各处有均匀的电流密度。但实际上,由于诸多因素,到达结构体各处的电流不可能是均匀的。针对阳极与结构体的距离及其布置、土壤电阻率变化、参比电极的位置等因素对电流分布的影响,进行了详细分析,得出结论:1.阴极保护设计成功与否关键是阳极布置,对于防腐层老化的管道采用柔性阳极,可有效改善电流分布;2.管-地电位测量的关键是将参比电极位于防腐层漏点处,可靠的方法是进行近间距管-地电位测量(CIPS)或用直流电压梯度法(DCVG)测量漏点处的实际保护电位;3.对于区域性阴极保护,应使参比电极位于被测结构体附近;4.防腐层漏点处的最小保护电位应低于-0.85V。
The degree of cathodic protection depends on the applied current density at the interface between the electrolyte and the structure. To achieve cathodic protection of the entire structure, a uniform current density should be applied throughout the structure. In practice, however, the current reaching the structure can not be uniform due to many factors. The influence of the distance between the anode and the structure and its arrangement, the change of the soil resistivity and the position of the reference electrode on the current distribution are analyzed in detail, and the conclusions are drawn as follows: 1. The key to the success of the cathode protection design is the anode arrangement , The aging of the anticorrosion pipeline with a flexible anode, which can effectively improve the current distribution; 2. Tube - ground potential measurement is the key to the reference electrode is located at the coating leakage point, the reliable method is to close pipe - ground potential measurement (CIPS) or by DC voltage gradient method (DCVG) to measure the actual protection potential at the leak; 3. For regional cathodic protection, the reference electrode should be located near the structure to be measured; Protection potential should be lower than -0.85V.