The Cathodic Protective Performance And Application Of Sacrificial Anode In Underground Water And Seawater Environment

Heat exchanger is the equipment prone to corrosion in industrial production. Due to the different structure and the different in-service conditions of the heat exchanger, corrosion problems of the heat exchanger persist all the time and solve the problems of corrosion of the heat exchanger becomes particularly important. Cathodic protection method is one of the effective measures to avoid exchanger corrosion and its process involved is more complex, such as a reasonable choice of anode material, a performance evaluation of anode material in the service environment, a design of cathodic protection and so on. These are frequently asked questions in cathodic protection process.This article through weight loss method, self-discharge method and polarization technique tested the protective properties of Zn anode and Al anode to 20# steel in the underground water and artificial seawater respectively, and picked preferably out the anode material being of good performance. This work was supported by the following important conclusions:(1) The corrosion rate of Zn anode and Al anode was tested respectively in the underground water and artificial seawater by weight loss method and the metal corrosion morphology was observed. The results suggest that in the underground water or artificial seawater the 20# steel coupled with Zn anode and Al anode was of lighter corrosion and production was easier to fall off, while the 20# steel without coupling was of more serious corrosion and had obvious pitting. It turns out that the sacrificial anode materials are provided with a good protection.(2) Through self-discharge method and polarization techniques tested the electrochemical properties of sacrificial anode system constituted by Zn anode, Al anode and 20# steel respectively in the underground water and artificial seawater at different temperatures, and under different temperatures drew the polarization curves and the open circuit potential/working potential versus time curve of Zn anode, Al anode and 20# steel. The results showed that, both in the underground water or artificial seawater, the excellent electrochemical performance of Zn anode and Al anode was exhibited and the potential reversal of Zn anode did not appear as the temperature rises.(3) On the basis of above research results, the actual use of heat exchanger in a chemical plant has been conducted by sacrificial anode cathodic protection engineering. According to the results of corrosion investigation and analysis of corrosion causes, the zinc anodes were installed in the heat exchanger. The equipment has been running for one year with a good protective effect, which shows the important theory significance and practical value of the research work.