Can carbon steel be used for desalinated water pipelines?
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The desalinated water pipes in our equipment are made of stainless steel, while the circulating water pipes are made of carbon steel. What do you think – can carbon steel be used for desalinated water pipes? Why?
No, because of corrosion, fluorinated lining pipes should be used.
Desalinated water is slightly alkaline, with a pH value typically ranging from 8 to 9. If carbon steel pipes are used, the high carbon content can lead to electrochemical corrosion, resulting in secondary contamination of the desalinated water. Since there are usually requirements regarding the cleanliness of desalinated water, corrosion-resistant materials should be used, such as stainless steel pipes. If the pipe diameter or length is large, it is advisable to conduct an economic analysis first. In fact, plastic-lined carbon steel pipes are also a good option; our factory uses such pipes.
We specialize in compressor demineralization water stations; in fact, many owners use carbon steel pipes, and that is how the design institutes specify it. There are also water stations with stainless steel pipes, while the owner’s pipes are made of carbon steel.
We are in the chemical and petrochemical industry; for plants built before the 1990s, the desalinated water pipelines were made of carbon steel, while for new plants constructed after 2000, they are mostly made of stainless steel or lined with PTFE.
The type of pipeline to be used depends primarily on the quality of the water used in the process. For example, in the titanium dioxide industry, the desalinated water used in the process must meet strict requirements regarding iron ions, as their presence can significantly affect the quality of titanium dioxide. If carbon steel pipelines are used, it will lead to secondary contamination of the desalinated water.
From a design perspective, carbon steel works. However, carbon steel pipes rust severely over time, resulting in excessive iron ions. So we switched to stainless steel a long time ago. Lined pipes are not recommended as their lifespan is short. What material? It depends on your capabilities.
For the pipelines of equipment, stainless steel is generally used, but for the demineralized water delivery lines within the plant, carbon steel is used due to their longer lengths