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Sulfuric acid dew point corrosion is a corrosion phenomenon that occurs in equipment such as boilers and industrial furnaces, where sulfuric acid vapor present in the flue gas condenses on low-temperature metal surfaces. The factors affecting this phenomenon can be categorized as follows: First, flue gas composition – the sulfur content in the fuel: Sulfur in the fuel burns to produce SO₂, which directly determines the total amount of SO₃ generated. The higher the sulfur content, the higher the concentration of sulfuric acid vapor in the flue gas, and thus the greater the risk of corrosion. Water vapor concentration: The amount of water vapor in the flue gas directly affects the amount of sulfuric acid vapor produced. An increase in humidity raises the acid dew point temperature, making it easier for sulfuric acid to condense. Excess air coefficient: Excess oxygen promotes the conversion of SO₂ to SO₃, increasing the proportion of SO₃ in the flue gases and thereby exacerbating corrosion. II. Temperature conditions: Metal wall temperature: The dew point temperature of sulfuric acid typically ranges from 110–150°C. When the wall temperature falls below this dew point, sulfuric acid begins to condense. Corrosion is most severe in the temperature range that is 20–50°C below the dew point. Sulfuric acid concentration: The corrosion rate follows a low-high-low pattern as the acid concentration changes; the corrosion effect on steel is most severe at sulfuric acid concentrations of around 40%-56%. III. Catalytic factors: Metal oxides such as Fe₂O₃ and V₂O₅ present in flue gas significantly accelerate the conversion of SO₂ to SO₃, indirectly increasing the production of sulfuric acid vapor and thereby exacerbating the risk of corrosion. IV. Factors related to the materials themselves: There are significant differences in the corrosion resistance of different materials. Experiments have shown that the corrosion resistance of GR2, ND, 316L, Corten, 20G, and 20 steel decreases in that order; among them, ND steel is an ideal material for corrosion resistance in flue gas deep cooling systems.