Corrosion sites and morphology of S-H₂S-RCOOH

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Corrosion in the S-H₂S-RCOOH system is concentrated in the high-temperature and high-flow areas of refining units, and its form exhibits distinct characteristics: First, the main areas affected by corrosion are the core regions of severe corrosion – the sections downstream of the outlet transfer line of the vacuum distillation unit and below the feed section of the vacuum tower; in some units that process crude oils with high acid values, corrosion also spreads to areas above the feed section of the vacuum tower. Secondary corrosion area: The corrosion degree in the oil transfer line at the outlet of the atmospheric pressure furnace and in the feed section of the atmospheric pressure tower is moderate. General corrosion area: The corrosion in the oil collection tank area of the coking distillation tower is relatively mild. II. Typical corrosion morphology: After corrosion, the surface of the steel remains smooth and free of impurities, with no accumulation layer typical of sulfur corrosion. Low-flow areas will develop corrosion holes with sharp edges. In areas with high flow rates and eddies, erosive pits or grooves with sharp edges appear, showing distinct characteristics of erosion corrosion.