Problems with valves for concentrated sulfuric acid
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Question 1: Why is calcium sulfate present in 98% sulfuric acid? Question 2: Do carbon steel ball valves or PTFE-lined ball valves used for 98% sulfuric acid pipelines experience difficulty in opening and closing over time? Is it because calcium sulfate precipitates on the surface of the ball valve, creating surface tension? Question 3: What type of valves and what material should be used for 98% sulfuric acid?
It’s unclear where the calcium sulfate comes from; carbon steel can also be used as it is inexpensive. Fluorinated linings are not affected by concentration changes. A better material option is a ceramic valve, which has good self-lubricating properties and is not affected by crystallization.
Calcium ions should be sourced from the raw materials; I’m not sure what your sulfuric acid production process is. Valves made of PTFE or stainless steel can be used; gate valves are a durable option
Carbon steel will do; it’s cheap and functional.
Over time, concentrated sulfuric acid forms acid sludge on its surface, making it difficult to turn the switch. Generally, carbon steel stop valves and PTFE diaphragm valves are used. A ball valve is one that can’t be opened or closed at the back, but if it’s used frequently, there’s no problem with that.