管道過保護(hù)判斷指標(biāo)

判斷陰極保護(hù)是欠保護(hù)還是過保護(hù)，判斷指標(biāo)是管道的斷電電位，不能以通電電位來判斷，因為通電電位中含有IR降。陰極保護(hù)電源(如恒電位儀)顯示的是通電電位，只要斷電電位不超標(biāo)，通電電位多大都沒關(guān)系。盡管實驗室的實驗證明了氫致開裂現(xiàn)象，但工程實踐中幾乎沒有發(fā)現(xiàn)氫致開裂的案例。因此，對于氫致開裂沒必要過度擔(dān)心，尤其是X80以下的鋼制管道，不需要考慮氫致開裂問題。

工程上常見的3LPE防腐層剝離現(xiàn)象,是由于工廠涂覆時質(zhì)量沒有控制好造成的，與陰極保護(hù)沒有關(guān)系。防腐層陰極剝離的前提是水的存在，而剝離的涂層下面沒有水，由于防腐層并沒有屬破損，陰極保護(hù)電流也無法到材達(dá)，所以不可能有氫氧根離子生成而導(dǎo)致環(huán)境堿性化。

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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.