Urgent! Urgent! Urgent! ! ! ! ! ! Note: Analysis of the cause of the demulsifier line leakage?

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The welds at the connection point between the feed demulsifier line for the atmospheric and vacuum distillation unit and the catalytic unit, as well as the demulsifier line itself within 10 cm of the injection point, suffer from frequent corrosion, resulting in small leaks. The raw material contains 20–30 mg of NaCl per liter, an acid value of 0.2–0.6, and approximately 0.1% moisture; the water injection point is located about 30 cm downstream from the demulsifier injection point. The material of the leakage pipeline is 20#. The diameters of the pipelines for injecting the demulsifier are Φ18×2.5 and Φ25×3. There were 8 leaks over a period of 2 years: 1 leak occurred in the pipeline with diameter Φ18×2.5, and 7 leaks occurred in those with diameter Φ25×3. The demulsifier used is oil-soluble, and the injection rate is approximately 1–1.5 L/h. The pressure at the leakage site ranges from 0.85–1.0 Mpa, while the temperature is between 125–140°C. For this year’s maintenance plan, the management has ordered that the material be upgraded to 316L. I’m concerned that chloride ions generated by the decomposition of chlorides could cause stress corrosion in stainless steel; in that case, it wouldn’t just be minor leaks caused by sand holes I wonder if it makes sense? I’d like experts to help analyze it! ! ! ! My own analysis of the reasons: Due to the low dosage of demulsifier used, the oil-agent mixing zone remains relatively stable. Within this zone, oil, agents, and brine formed after demulsification are present, at a temperature of around 125–140°C; as a result of the decomposition of chlorides, corrosion caused by H2S-HCl-H2O occurs in certain areas