Cathodic protection
发布时间：2019-06-13
Cathodic protection
Cathodic protection is an anti-corrosion method based on the principle of electrochemical corrosion. The American Association of Corrosion Engineers (NACE) defines cathodic protection as reducing the corrosion rate by applying an applied electromotive force to shift the corrosion potential of the electrode to a lower oxidation potential. Sacrificial anode cathodic protection is to connect or weld metals with negative potential on metal structures, such as aluminum, zinc or magnesium. The anode material is continuously consumed, and the current released is supplied to the protected metal structure while the cathode polarizes, thus realizing the protection. External current cathodic protection (ECCP) is to make the cathodic polarization of the protected metal by applying cathodic current to the protected metal through an external DC power supply. This method is mainly used to protect metal structures in large or high soil resistivity soils.
Protective potential refers to the potential needed to stop (or neglect) metal corrosion during cathodic protection. In practice, the protective potential of steel is - 0.85V (CSE). That is to say, when the metal is at a potential more negative than - 0.85V (CSE), the metal is protected and the corrosion can be neglected.
Cathodic protection is an effective method to control corrosion of steel storage tanks and pipelines. It can effectively remedy the corrosion caused by coating defects and greatly prolong the service life of storage tanks and pipelines. According to the information provided by a cathodic protection engineering company in the United States, from the economic point of view, cathodic protection is one of the most economical means to prevent corrosion of steel storage tanks.
