Positions on the heat exchange tube bundle that are prone to corrosion
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I would like to ask: are tube bundles with a phase transition in the medium more prone to corrosion compared to those without such a phase transition? Are the corrosion sites mainly concentrated at the bends (U-shaped areas) and the inlets and outlets of the tube bundle? Could uneven vapor-liquid distribution within the tube bundle also lead to increased corrosion?
Based on our company’s experience, stress does concentrate at the import point and at the bends of the U-shaped tubes; if appropriate measures are not taken, leaks will occur in these areas. Stress-relief treatment is necessary in all such cases whenever possible.
At the bent sections, it is estimated that residual stress concentration occurred due to the fact that the factory did not carry out stress-relief annealing after cold bending, or the annealing process was inadequate, which increases the likelihood of corrosion； Is it related to the expansion welding process used by the equipment manufacturer at the pipe ends? Of course, in some domestic factories that only conduct eddy current testing, they usually do not cut off 200 mm from the pipe ends, which also poses risks at those ends.
Problems tend to occur in areas with stress concentration