The corrosion of storage tanks in seawater is mainly electrochemical corrosion, that is, microcurrent is generated during the corrosion process. From the principle of electrochemistry, it can be seen that the cathode of the corrosion cell does not corrode, but only the anode corrodes. Therefore, turning the protected metal into a cathode can prevent the corrosion of the metal. This method is called cathodic protection.
Under the influence of international oil prices, state-owned enterprises, private enterprises, especially local ports, are investing in the construction of crude oil reserves. Water pressure testing is an indispensable process in the construction of large storage tanks. Under the influence of geographical conditions and economic conditions, most oil reserve projects use seawater for pressure testing. In order to reduce the corrosion of steel plates by seawater during the test, temporary cathodic protection needs to be installed at relevant parts of the storage tank. In order to determine the form and quantity of cathodic protection, combined with GB50393-2008 and other relevant specifications, taking a 100,000 cubic storage tank as an example, the number of cathodic protection required for a 100,000 cubic storage tank is calculated, and it is applied in the project. The rationality of the calculation is verified through practical application.
In the Tianjin National Petroleum Reserve Base Project, seawater was used for water pressure testing of storage tanks. According to the above calculations, aluminum-magnesium-indium-cadmium alloy anodes were used for cathodic protection. After the water filling test, it was found that the protection effect of the anode was good, which greatly reduced the corrosion of seawater to the steel plate.