Terrible pitting corrosion

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In a certain refinery, a leak was detected in the tube bundle of a water cooler after less than half a year of use. Inspection of the tubes revealed that poor quality of the circulating water had caused pitting corrosion on the inner surfaces of the heat exchange tubes; as shown in Figures 1–3, it was this pitting corrosion that led to the failure of one of the heat exchange tubes. A heat exchanger has nearly 400 heat exchange tubes, and this time it was found that a dozen of them were leaking, all suffering from pitting corrosion. Although the blind plug is used to seal the pipe, it does not guarantee that there will be no other pitting corrosion. Therefore, this heat exchanger tube bundle can only be used for about 1 year before it needs to be discarded. It is designed to last for over 5 years, but the equipment’s service life has been reduced due to poor management. That’s why similar devices are most vulnerable to pitting corrosion.