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

Thread Content

Corrosion of the inner wall of oil tanks and anti-corrosion methods: 1. The types of corrosion that occur on the inner wall of oil tanks are as follows: (1) Concentration cell corrosion: This occurs mainly below the liquid level on the inner wall of the oil tank, due to differences in oxygen concentration. ⑵Electrochemical corrosion: This is the most common and harmful type of corrosion, occurring 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 the oil are the main causes of electrochemical corrosion. ⑶Sulfate-reducing bacteria: mainly found at the bottom of the tank. Friction corrosion mainly occurs at the floating expansion joints of floating roof tanks. 2. Corrosion prevention measures ⑴ Corrosion resistance 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 ； Second, it must be able to withstand immersion in petroleum products throughout the year, without contaminating the oils or causing them to deteriorate. ⑵Standard solution: The typical anti-static and anti-corrosion coating system for the inner walls of oil storage tanks consists of an epoxy zinc-rich primer (applied in 2 coats by brushing or spraying, with a thickness of 100μm) + an antistatic anti-corrosion topcoat (applied in 2–3 coats by brushing or spraying, with a thickness of 100–150μm). 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 solution is composed of special resins, special pigments, and conductive fillers, and it possesses excellent antistatic and anti-corrosion properties.