Can stainless steel be used for equipment involving secondary brine?
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May I ask if stainless steel can be used for equipment related to secondary brine? Such as clarification tanks. Thank you!
For barium sulfate clarification tanks, what materials do you all use?
Since secondary brine contains hydrochloric acid used to \"wash\" the resin, and thus has chloride ions, I believe stainless steel cannot be used
Sure, if costs are not a concern
Stainless steel is not recommended for saltwater systems, as chloride ions cause corrosion in stainless steel. Unless you opt for a higher-grade steel such as duplex steel, which could be considered an option, it might be excessive to use such a premium material – it’s not cost-effective. Generally speaking, for the sulfate removal clarification tank in your barium process, using 235B-lined fiberglass scales is more than sufficient to meet the production requirements.
For saline solutions, it is generally recommended to use equipment and pipes made of carbon steel with a plastic lining; equipment lined with glass flake is also an option. If cost is not a concern, duplex steel 2205 is suitable for storing saline solutions at temperatures up to 40°C, while for higher temperatures, 2507 should be considered
Secondary brine systems generally use rubber lined with low calcium and magnesium content; the primary brine pretreatment units are coated with glass flake. Stainless steel is not as resistant to chloride ions as ordinary Q235 carbon steel.
The clarification tank is defined as a device for secondary brine, which is quite unusual. The secondary brine system generally consists of the pipelines from the resin tower to the electrolytic cell and the storage tanks. Since the impurities in the secondary brine after adsorption by chelating resins are all within the ppb (10-9) range, to prevent the secondary brine from being contaminated again before it enters the electrolyzer, the material selection for the equipment and its pipelines is more stringent than that for the primary brine. Materials with low calcium and magnesium content are required, such as low-calcium-magnesium rubber, CPVC, titanium, etc. Therefore, the clarification tank is not strictly considered a secondary brine system. The clarification tank contains dechlorinated brackish water. During the start-up and shutdown of the system, or in cases where control is poor during dechlorination, acidic water or chlorinated brine can cause severe corrosion to stainless steel.
Using rubber lining or glass flake lining is sufficient – it’s cheap and durable; why choose stainless steel then?