Discussing methods for preventing corrosion on the inner walls of petrochemical storage tanks

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Anti-corrosion methods for the inner walls of petrochemical tanks: We know that there are several types of corrosion that can occur on the inner walls of tanks. One type is concentration cell corrosion, which occurs mainly below the liquid level in the tank, as a result of differences in oxygen concentration. The second is galvanic corrosion (electrochemical corrosion), which is the most common and harmful type of corrosion; it occurs primarily at the bottom, walls, and top of the tank. The anodic and cathodic regions in electrochemical corrosion are formed due to potential differences caused by factors such as the microscopic heterogeneity of the material itself, while water, salts, acids, etc. present in oil products are the main causes of electrochemical corrosion. Third is corrosion caused by sulfate-reducing bacteria and other bacteria, which mainly occurs at the bottom of the tank. Friction corrosion mainly occurs at the floating expansion joints of floating roof tanks. Coating anti-static and anti-corrosive coatings on oil product storage tanks requires different standards from those for other industrial coatings; it must meet two requirements: first, in addition to having anti-static properties, it must also provide excellent rust prevention for steel ； The coating inside the tank is in contact with petroleum products, and this environment facilitates the penetration of corrosive agents through the paint film and thus causes corrosion of the steel ； Second, it must be able to withstand immersion in petroleum products throughout the year, without contaminating the oils or causing them to deteriorate. The common approach for applying antistatic and anti-corrosive coatings to the inner walls of oil storage tanks is also one of the mainstream methods used for preventing corrosion on the inner surfaces of such tanks at present. The protection method is: epoxy zinc-rich primer (applied by brushing or spraying in 2 coats, with a thickness of 100 μm) + antistatic corrosion-resistant topcoat (applied by brushing or spraying in 2–3 coats, with a thickness of 100–150 μm). The primer in this solution is composed of modified epoxy resin, zinc powder, and a high-performance curing agent. It uses the principle of sacrificial anode protection to prevent corrosion, with the zinc powder releasing electrons to prevent iron from corroding. This primer dries quickly, has excellent resistance to penetration, outstanding corrosion resistance, and strong adhesion, making it suitable for use in tank farm environments. The topcoat is composed of special resins, special pigments, and conductive fillers, and it possesses excellent antistatic and anti-corrosion properties. Of course, when it comes to corrosion protection for the inner walls of oil storage tanks, we follow these principles: in addition to antistatic properties, the coating must provide excellent rust prevention for steel, must be able to withstand years of exposure to petroleum products, and must not contaminate the oil or cause it to deteriorate. By primarily adhering to such principles, more cost-effective anti-corrosion materials can be developed.