管道过保护判断指标 Judgment index of pipeline overprotection

管道过保护判断指标

判断阴极保护是欠保护还是过保护，判断指标是管道的断电电位，不能以通电电位来判断，因为通电电位中含有IR降。阴极保护电源(如恒电位仪)显示的是通电电位，只要断电电位不超标，通电电位多大都没关系。尽管实验室的实验证明了氢致开裂现象，但工程实践中几乎没有发现氢致开裂的案例。因此，对于氢致开裂没必要过度担心，尤其是X80以下的钢制管道，不需要考虑氢致开裂问题。

工程上常见的3LPE防腐层剥离现象,是由于工厂涂覆时质量没有控制好造成的，与阴极保护没有关系。防腐层阴极剥离的前提是水的存在，而剥离的涂层下面没有水，由于防腐层并没有属破损，阴极保护电流也无法到材达，所以不可能有氢氧根离子生成而导致环境碱性化。

Judgment index of pipeline overprotection

To judge whether cathodic protection is under protection or over protection, the judgment index is the power-off potential of the pipeline, which cannot be judged by the energization potential, because the energization potential contains IR drop. The cathodic protection power supply (such as potentiostat) shows the energizing potential. As long as the power-off potential does not exceed the standard, it does not matter how much the energizing potential is. Although laboratory experiments have proved the phenomenon of hydrogen induced cracking, few cases of hydrogen induced cracking have been found in engineering practice. Therefore, there is no need to worry too much about hydrogen induced cracking, especially for steel pipes below X80.

The common peeling phenomenon of 3LPE anticorrosive coating in engineering is caused by the poor quality control during coating in the factory, which has nothing to do with cathodic protection. The premise of cathodic stripping of anticorrosive coating is the existence of water, and there is no water under the stripped coating. Since the anticorrosive coating is not damaged and the cathodic protection current can not reach the material, it is impossible for hydroxide ions to be generated, resulting in alkalization of the environment.