The corrosion problem of pure water (a tough issue)
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This post was last edited by Litaotao1314 on 2011-5-29 at 20:29. The heat exchangers in our factory are made of stainless steel, while the pipes are made of carbon steel. Currently, reverse osmosis pure water is used for cooling the heat exchangers; however, the carbon steel pipes are suffering from severe corrosion. The system is not open-type, and the water appears yellow in color. What measures can be taken to control this situation? 1. I want to use an anti-corrosion lining, but the existing pipes cannot be modified. 2. Adding a corrosion inhibitor does not yield satisfactory results; I’m seeking help from forum friends to get some good suggestions! Thank you!
To resolve this completely, it seems that replacing the pipes is the only option. It is recommended to use non-metallic pipes; plastic composite pipes with a steel framework are a good choice at present. Please consider this option.
There’s a problem with your water; is its pH level within the acceptable range? We’ve had similar problems, but not as severe as yours – an imbalance between cationic and anionic resins, and the pH level was not within the acceptable range
Exposed steel-reinforced composite pipes are not suitable; buried pipes are okay. Exposed pipes suffer severe aging due to ultraviolet rays, and they also experience significant thermal expansion and contraction. If possible, it’s better to use higher-quality stainless steel pipes.
What grade of pure water? Carbon steel pipes are probably not suitable.
Check the effectiveness of the reverse osmosis process to see if the electrolyte level is too high
We have encountered such problems as well. Seeking advice from experts.
It is necessary to keep the pH value within the normal range
Ammonia water is added to adjust the pH to 9-9.5; power plants use this method, and it yields very good results.
Is corrosion caused by dissolved oxygen?
Coupling corrosion occurs when stainless steel and carbon steel act as the anode and cathode, respectively; together with the presence of dissolved oxygen, this leads to the formation of compounds of ferrous and ferric ions, resulting in a yellow solution. Cathodic protection is recommended ； Adjusting the pH to 9-9.5 to suppress the reaction is theoretically feasible; I haven’t used this method in practice, so I’m not aware of its effectiveness, but it’s worth giving a try.