Differences between sulfuric acid and hydrochloric acid valves
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What is the difference between valves for sulfuric acid and hydrochloric acid? Our company plans to build one storage tank for sulfuric acid and one for hydrochloric acid, each with a capacity of 10 tons. What material should be used for the valves? This post was last edited by chinazwr on 2009-2-16 18:03]
It is recommended to use fiberglass-reinforced plastic for hydrochloric acid storage tanks, while polypropylene should be used for valves and pipelines； If pressure resistance is required, a rubber-lined material can be used. As for sulfuric acid, it depends on the specific situation; concentrated sulfuric acid does not cause much corrosion to metals, so carbon steel is usually sufficient ； If it is dilute sulfuric acid, enamel-lined or titanium-lined equipment should be used.
For hydrochloric acid, fiberglass-reinforced plastic valves are used. For sulfuric acid, the appropriate type of valve depends on the specific circumstances; since concentrated sulfuric acid does not react with iron, ordinary carbon steel valves can be used, or valves lined with plastic can also be employed. Carbon steel valves must never be used for dilute sulfuric acid – valves lined with plastic or enamel are required in such cases
For hydrochloric acid, fiberglass valves are used. Fiberglass valves can be made from: 1. Phenolic resin, 2. Epoxy resin – not suitable for use at temperatures above 66 degrees; 3. Furan resin – not recommended for use. Concentrated sulfuric acid does not react with iron, so ordinary carbon steel valves can be used in this case. I disagree with this approach – some manufacturers, after using the vessels, allow water vapor from the air to cause the residual concentrated acid on the surface of the steel to become diluted acid, thereby leading to corrosion. It’s unexpected, right? A little corrosion on the tanks and pipes isn’t a big problem, but if the sealing surfaces of the valves are corroded, leaks will occur. Why make things so complicated? It would be sufficient to use fluoroplastic ball valves – after all, fluoroplastic valves aren’t expensive these days :) :)
It is recommended to use fluoroplastic valves and pipes at the tank outlet and at the valve
Without knowing the temperature and composition, it’s difficult to make a determination one by one; however, if the temperature is below 200 degrees Celsius, a PTFE-lined valve is a good choice. If the temperature is higher, a TA valve or a glass-lined valve should be used.