Pipelines are rusting
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Why do pipelines using chilled water rust faster than those using CW, and why isn’t stainless steel material used for these pipelines?
Pipes made of stainless steel are of course much more expensive.
Pipelines using chilled water rust faster than those using CW, because the insulation is not adequate
Chilled water is generally saltwater, and based on what the poster mentioned, their chilled water should be saltwater. Most stainless steels are sensitive to chloride ions, and using them may cause faster corrosion.
If by chilled water you mean an ethylene glycol aqueous solution, then its corrosion rate will not be faster than that of CW; if it is saltwater, then its corrosion rate will definitely be faster than that of CW
If you are willing to invest in proper anti-corrosion measures, the material will naturally not rust. Moreover, regular anti-corrosion tests are necessary, which also involves costs
Chilled water generally contains inorganic salts such as NaOH, while CW, which is used for heat removal, does not contain such salts; therefore, chilled water is more corrosive than cooling water. Water containing NaOH can use carbon steel pipes.
1# wangkai6191: The chilled water pipes do not need to be made of stainless steel, as refrigerants are usually non-corrosive.
1# wangkai6191 The outer wall of frozen water pipes rusts easily due to dew formation; therefore, it is important to ensure high quality in the construction of the moisture-proof layer.
I think that if it’s outside the pipe wall, the temperature of the chilled water is lower, which makes condensation more likely; over time, this can lead to rusting. On the other hand, the temperature of cooling water is higher, so condensation is less likely, and thus rusting is also less probable. It’s possible that the insulation around the pipe isn’t adequate. In our factory, the insulation on the chilled water pipes is of high quality; they’ve been in use for over a decade or two, and they don’t rust easily! Using stainless steel is a viable option in our environment and with the type of water we use, but the cost is too high.
1. Insulating the chilled water pipes is essential; there’s no need to discuss it. 2. Chilled water is usually brine. -A sodium chloride solution is used when the temperature is above 10°C; a mixture of sodium chloride and calcium chloride is used at lower temperatures, while a calcium chloride solution is used when the temperature is even lower. 3. Corrosion inhibitors must be added to frozen brine; there are many types, such as sodium dichromate. Generally, seamless pipes are fine.