Corrosion assessment
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Could everyone help determine the cause of corrosion? The material is 316, and the medium inside the tower is coal tar.
Analyze whether there are chloride ions in coal tar; a high concentration of chloride ions has a strong corrosive effect on 316 material.
In the areas severely affected by corrosion, monitoring in previous years showed that the chlorine level was below approximately 40 ppm. It’s the new tower of the year. The corroded area contains 0.8-0.9% sulfur, and the temperature is around 300°C. Could you help determine the difference between sulfur corrosion and chlorine corrosion?
It looks like intergranular corrosion; is there any corrosion in the heat-affected zone of the weld?
In the third photo, the part marked with a white circle at the bottom has a horizontal weld