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The oil stored in metal tanks often contains corrosive chemicals such as hydrogen, sulfuric acid, organic and inorganic salts, and water. Additionally, due to the effects of environmental factors on the outer walls of the tanks, their lifespan is shortened. If metal oil tanks are not treated for corrosion in a timely manner, it may affect the quality of the oil at the least, and can lead to oil leaks that contaminate the environment; it also increases the risk of fires and explosions. Therefore, it is very necessary to apply anti-corrosion treatment to metal oil tanks. 1. Usage of light oil tanks: Light oil tanks refer to storage tanks used for holding light petroleum products such as gasoline, diesel, and kerosene. Light petroleum products with high volatility, like gasoline, are more corrosive than heavy petroleum products with lower volatility; the corrosion is particularly severe in the gas phase area. The outer wall of the tank body of such oil storage tanks is prone to chemical corrosion, while the interior of the tank is susceptible to several other types of corrosion. Due to the high solubility of oxygen in light oil, some of the dissolved oxygen can enter the water at the bottom of the tank; as a result, mild galvanic micro-corrosion and oxygen concentration cell corrosion still occur at the tank bottom. Moreover, the specific corrosion conditions of such oil storage tanks also vary depending on the medium. Furthermore, petroleum products, especially light oils, are often subjected to friction, impact, collision, and compression during their production, storage, and use. During processes such as oil tank spraying, shaking, filling, and flushing, a large amount of static electricity can be generated, which may lead to electrostatic ignition and explosions; such damages are extremely dangerous. 2. Corrosion environment of light oil tanks: The internal corrosion of oil tanks is related to factors such as the type and properties of the stored medium, temperature, and the design of the oil tank. There are two corrosion environments inside the oil tank: one is the liquid phase and the other is the gas phase. For oil tanks with a temperature of less than 100°C and a water phase, the liquid phase is divided into two layers; in addition to the oil layer, there is usually a water layer at the bottom of the tank. For fixed-roof oil tanks, the corrosion characteristics in various internal areas are as follows: the tank roof and the upper part of the tank walls. This area does not come into direct contact with the oil, so it is subject to gas-phase corrosion. According to the mechanisms of atmospheric corrosion, it falls under the category of electrochemical corrosion; corrosion occurs through a condensed water film, and under the influence of harmful gases such as SO2, CO2, H2S, and O2, a corrosive galvanic cell is formed. Due to the thin water film, oxygen can diffuse easily, so oxygen-consuming corrosion plays a dominant role. Corrosion at the gas-liquid interface on the tank wall is corrosion under oxygen concentration cell conditions, and it is one of the most severe areas of corrosion on the tank wall. Self-supporting fixed roofs can sometimes experience stress corrosion in high-stress areas. Middle of the tank wall. The middle part of the tank wall is in direct contact with the oil, and its corrosion is primarily due to the chemical effects of the oil; thus, this area suffers the least degree of corrosion. However, in oil tanks where the liquid level changes frequently, corrosion at the gas-liquid interface is relatively severe. The lower part of the tank wall and the upper surface of the tank bottom plate. This area is the most severely corroded part of the oil tank, primarily due to electrochemical corrosion. During storage and transportation, moisture accumulates on the bottom plate of the tank, forming a layer of oily wastewater with high salinity, which leads to electrochemical corrosion. Typically, oily wastewater contains Cl- and sulfate-reducing bacteria, as well as harmful gases such as SO2, CO2, and H2S, making it highly corrosive. Concentration cell corrosion occurs at the interface where oil and water meet on the lower part of the tank wall and the upper surface of the tank bottom plate. When a heating coil is installed on the base plate, local corrosion is exacerbated by temperature and the thermocouple effects resulting from welding. Due to the outward slope at the bottom of the tank, corrosion is most severe at the junction between the tank wall and the bottom, making it a key area that requires special protection against corrosion. In addition to uniform corrosion on the upper surface of the tank bottom plate, local corrosion (especially pitting and crevice corrosion) is very severe, which is the main cause of perforations in the bottom plate. Exposed fixed roof and tank walls. It belongs to atmospheric corrosion. According to the mechanisms of atmospheric corrosion, it falls under the category of electrochemical corrosion; corrosion occurs through a condensed water film, and under the influence of harmful gases such as SO2, CO2, H2S, O2, etc., a corrosive galvanic cell is formed. Due to the thin water film, oxygen can diffuse easily, so oxygen-consuming corrosion plays a dominant role. Corrosion is most severe under industrial and marine atmospheric conditions. Lower surface of the oil tank bottom plate. It is mainly soil corrosion and water corrosion. Furthermore, due to the difference in air permeability between the central part of the base and its surrounding areas, an oxygen concentration cell is formed, with the central part acting as the anode and thus suffering from corrosion ； The stray currents underground can also exacerbate floor corrosion ； Ground electrodes can cause galvanic corrosion, and the use of zinc ground electrodes can effectively reduce it. Furthermore, gap corrosion occurs at areas within the oil tank where the internal structure is not airtight, such as at intermittent weld seams. 3. Analysis and discussion of corrosion mechanisms: Metal corrosion occurs under the influence of two or more factors, and the same is true for the corrosion of light hydrocarbon storage tanks. Electrochemical corrosion caused by the moisture contained in light hydrocarbon liquids occurs because, for production purposes, small amounts of water are mixed into the light hydrocarbons; at the places where the coating is damaged, iron reacts electrochemically with water. This should be analyzed from the perspective of galvanic corrosion. When the anti-corrosion coating is damaged, the potential of the exposed metal is more negative (the standard electrode potential for iron is -0.44 V), while the electrode potential of the coating is more positive; this creates a corrosion cell between the exposed metal and the coating. The anode is the metal exposed beneath the damaged coating, while the cathode is the coating that has not been damaged. It is particularly important to emphasize that the corrosion cell formed here has a large cathode and a small anode; under such conditions, the corrosion rate increases exponentially, resulting in the higher corrosion rate mentioned above. It can be seen that the final product of hydrogen sulfide corrosion is FeS. Although the FeS film is insoluble in light hydrocarbon liquids, it does not provide protection; the corrosion process mentioned above can continue beneath the film, and at an even faster rate. 4. Current status of corrosion prevention and several anti-corrosion measures. In light of the above issues, it is recommended to adopt the following protective measures: using anti-corrosion coatings for protection. Coating protection is the most practical and cost-effective protection measure for lightweight storage tanks. The reasons for coating damage are mostly poor adhesion of the paint, pinholes in the coating, poor solvent resistance, and weak resistance to the penetration of light hydrocarbon liquids. Therefore, the following principles should be followed when selecting coatings: excellent adhesion ； Excellent water resistance ； Stable solvent resistance (light hydrocarbon liquids) ； Good flexibility and impact resistance ； Good workability, meaning good leveling properties, no sagging, and a moderate surface drying time. Regular inspections. Conduct an external inspection of the oil tank at least once a year, and carry out a thickness measurement inspection of the oil tank at least once a year. For storage tanks that are severely corroded, such as those holding semi-finished products like gasoline and kerosene that are highly susceptible to corrosion, inspections should be carried out once a year; any issues found should be repaired promptly. Furthermore, considering cost-effectiveness, necessary material upgrades can be considered.