Corrosion and anti-corrosion of the inner wall of oil tanks

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This post was last edited by Wang Wei2 on July 29, 2024, at 10:12. 1. The following types of corrosion occur on the inner walls of oil tanks: (1) Oxygen concentration cell corrosion: This type of corrosion mainly occurs below the liquid level on the inner walls of oil tanks, caused by differences in oxygen concentration. Primary cell corrosion (electrochemical corrosion) is the most common and damaging type of corrosion; it primarily occurs on the tank bottom, walls, and roof. ⑵Electrochemical corrosion: The anodic and cathodic regions in electrochemical corrosion are formed due to potential differences resulting from microscopic heterogeneities in the material itself, while water, salts, acids, etc. present in the oil are the main causes of electrochemical corrosion. ⑶Sulfate-reducing bacteria corrosion: Corrosion caused by sulfate-reducing bacteria and other bacteria, which mainly occurs at the bottom of tanks. ⑷Fretting corrosion: Fretting corrosion primarily occurs at the floating and telescoping joints of floating roof tanks. 2. Corrosion protection ⑴ Coating requirements: Anti-static and corrosion-resistant coatings must be applied to oil product storage tanks. These requirements differ significantly from those for other industrial coatings; such coatings must meet two conditions: first, in addition to having anti-static properties, they must also provide excellent rust prevention for steel ； The coating inside the tank is constantly immersed in petroleum products; this immersion condition is more conducive to the penetration of corrosive agents through the paint film and subsequent corrosion of the steel than exposure to atmospheric conditions ； Secondly, it must be able to withstand immersion in petroleum products throughout the year, without contaminating the oils or causing them to deteriorate. ⑵Recommended solution: Based on the above analysis, and with reference to the anti-corrosion coating used for the inner walls of crude oil tanks, we recommend the following anti-static and anti-corrosion coating system for the inner walls of petroleum storage tanks: epoxy zinc-rich primer + anti-static anti-corrosion topcoat. 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 of this system is composed of special resins, special pigments, and conductive fillers; this coating exhibits excellent anti-static and anti-corrosion properties.