Material selection for 30% hydrochloric acid control valve
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There is a control valve with the following operating conditions: pipe diameter of DN15, temperature at normal levels, pressure of 0.2 Mpa, and the medium is 30% hydrochloric acid. What type of valve should be chosen? In particular, what materials should be used for the valve body, valve stem, valve seat, and packing? I would appreciate your advice. Thank you!
The requirements for the material of valve bodies are generally higher than those for pipeline materials. Given the corrosive nature of hydrochloric acid, Hastelloy is usually used
It seems that control valves cannot be made in such small diameters; the smallest available diameter is DN20! (There are now valves for regulating very small flow rates.) Plastic ball valves are a better option – they are inexpensive, of decent quality, and have a fast delivery time. If high precision in regulation is required for your application, using valves with a full PTFE lining would be sufficient; there’s no need to use Hastelloy materials (as they are too expensive and have a long delivery time). Is this answer satisfactory to you? QQ: 928976489 (Italian LAPAR)
Tantalum metal is likely the most resistant to hydrochloric acid corrosion, followed by silver and nickel-iron alloys.
It seems that control valves cannot be made in such small diameters; the smallest available diameter is DN20! (There are now valves for regulating very small flow rates.) Plastic ball valves are a better option – they are inexpensive, of decent quality, and can be delivered relatively quickly.:handshake
Based on the corrosion charts and material selection tables for hydrochloric acid concentration and temperature, it is recommended to use nickel-iron alloys; Hastelloy is a good alternative. If funding is limited, options with rubber linings can also be considered.
Those made of PVC are better; Japanese brands from Tokogu are a good choice, and domestic options are also available. Avoid those made of metal or PTFE! It is widely used in ion-exchange membrane caustic soda plants. Last edited by sunyork on 2009-3-10 14:33.]
I’m sorry, I made a mistake; it’s a nickel-molybdenum alloy, not a nickel-iron alloy.
A ceramic diaphragm will suffice; to save costs, plastic diaphragms or those treated with PTFE can be used, but the issue of material aging must be taken into consideration.
For such industrial applications, it is not necessary to use control valves; instead, metering pumps are a good choice – they work well and can be controlled using 4-20mA signals
It’s PVC, I guess. We have one with a higher concentration than yours; everything used is made of PVC
The poster cannot use valves made of precious metal alloys – they are too expensive; plastic control valves are a good option.
Hastelloy B, C, tantalum, zirconium, ceramics,
SAMSON PTFE-lined valve
It’s possible using an NDV diaphragm valve. The problem is that the delivery time might be quite long.
A fluorinated single-seat control valve can be used, or a metering pump is also an economical option; there are many experts on the forum
A fluorinated single-seat control valve can be used, or a metering pump is also an economical option; there are many experts on the forum
If you want to save money, choose a fully lined valve (with bellows seal)； If you want something high-end, use Hastelloy C