Analysis of corrosion on the outer wall of 321 stainless steel heat exchange tubes
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The corrosion of the outer wall of the heat exchange tube is as shown in the figure. The medium is steam condensate water with a temperature of 300°C. Please help analyze the cause of the corrosion in this situation.
To add, the corrosion location is at the gas-liquid contact surface. There is a small amount of scale on the tube wall. All heat exchange tubes are corroded and fractured at the gas-liquid contact surface.
Are there chloride ions in the steam condensate?
Is it a steam generator? Is there any bubbling? Are there any patterns in the locations of corrosion, such as the uppermost heat exchange tube?
Stress corrosion cracking. Check whether materials or circulating water are mixed in the steam condensation water. Measure the chloride ions and ph value in the steam condensation water.
Mostly related to dissolved oxygen content.
Stress corrosion, my personal opinion is that the impact stress caused by the phase change of this medium affects the metal, which is similar to the cavitation of machine pumps.
study* For a while, I always thought that dissolved oxygen corrosion would not be serious.