How to determine sulfuric acid dew point corrosion

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I. Key criteria for judgment: Verification of operating conditions – It is necessary to confirm that the equipment is in an environment with flue gases resulting from the combustion of sulfur-containing fuels, and that the temperature of the metal surfaces remains below the sulfuric acid dew point range of 110–150°C over an extended period; corrosion is most severe when the temperature is 2–50°C below the dew point. Macroscopic morphology observation: The cross-section of the corrosion product exhibits a typical three-layer structure: an outer layer that is loose and grayish-black, a middle layer consisting of gray deposits, and an inner layer that is dense, white, and shiny due to the corrosion reaction. Component analysis provides support: elemental analysis of the corrosive deposits is carried out, and an abnormally high sulfur content, if detected, is a key indicator for determining sulfate dew point corrosion. Auxiliary methods for confirmation: By combining scanning electron microscopy (SEM) to observe the microstructure of corrosion, along with an energy dispersive spectrometer (EDS) to analyze the elemental composition of the corrosion products, it is possible to further determine the cause of corrosion.