Terrible pitting corrosion
Thread Content
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 plugs are used to seal the pipes, it cannot be guaranteed 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.
It seems that both the material quality and water quality need to be taken into account
Bacterial corrosion – there may be issues with oil leakage and sterilization management in the circulating water system.
The management of heat exchangers is a systematic approach that involves paying attention to these key aspects as a whole. First is the water quality management of circulating water ； Second is the customization of heat exchanger tubes, particularly the materials used for the tube bundles, with proper attention paid to the acceptance process ； Secondly, the heat exchangers for circulating water, which consist of carbon steel tube bundles, require anti-corrosion treatment.
This post was last edited by Wang Wei2 on 2019-1-2 at 16:26. The corrosion of water cooler tube bundles is generally addressed from two aspects. Firstly, in terms of process management, it is necessary to improve the control of circulating water, add appropriate corrosion inhibitors, and conduct proper evaluations to keep the corrosion rate within acceptable levels; this requires professionals skilled in water quality management to handle it. Second is the corrosion protection of the heat exchanger tube bundles; here, it mainly refers to the corrosion protection of carbon steel tube bundles. Generally, the best approach for corrosion protection is to combine anti-corrosion coatings with sacrificial anodes to achieve optimal protective effects. I have used anti-corrosion coatings on water coolers, and after 8 years they are still performing very well. As shown in the figure below, this is for a usage period of 3 years.
Aren’t there ones now where the tubes are directly made of stainless steel? This problem should be solvable now
Stainless steel is not recommended for use in environments containing chloride ions. Additionally, stainless steel has low heat transfer. Second, the cost is high, and it cannot be used in some environments.