Should sodium sulfate wastewater at 1.5% be treated with carbon steel or stainless steel?

If the temperature is not high, use storage tanks or pipes lined with PE

According to current environmental standards, stainless steel is still the better choice.

This post was last edited by Wang Wei2 on 2019-6-6 at 14:30. In a simple sodium sulfate aqueous solution, the corrosion rate of carbon steel is no more than 0.5 mm per year (when pH is greater than 7), while the corrosion rate of stainless steel is less than 0.05 mm per year. It is clear that using stainless steel is the better choice. But what we are discussing here is the 1.5% sodium sulfate wastewater in wastewater treatment projects. Choosing stainless steel blindly in this case is not necessarily safe. Because there are other unknown corrosive agents in the wastewater. If the operating pH is below 7, meaning it is acidic, and the wastewater contains ions such as chloride and fluoride, it is not recommended to use stainless steel. When other corrosive agents in the wastewater cannot be identified, the coupon testing method can be used to screen for corrosion-resistant materials. For paint-coated test pieces (or those with prior experience in this area), examine the corrosion resistance of metal test pieces. Choose a material with good overall performance to use as containers or pipes.

Thank you, moderator; I’ve learned another thing to keep in mind

This post was last edited by newsdom on 2019-6-18 at 16:22. Plastic pipes are used; PE pipes with a steel framework are the best choice, as they allow for larger spans and make it easier to lay them overhead. Reinforced PP pipes work as well; generally, it is recommended to lay them along the ground. Using stainless steel incurs high costs, and it is also not resistant to corrosion caused by chloride ions and similar substances. Carbon steel pipes are also not resistant to corrosion by dissolved oxygen