Butterfly Valves for Chlor-Alkali Plants
PVDF-lined butterfly valves for wet chlorine gas, Hastelloy C-276 and titanium ball valves for hydrochloric acid, and SS316L diaphragm valves for caustic soda (NaOH) service.
Which butterfly valves are used for chlor-alkali plants?
Chlor-alkali plants produce chlorine, caustic soda (NaOH), and hydrogen from the electrolysis of brine - three process streams that each require completely incompatible valve materials. Wet chlorine gas attacks almost every common metal; HCl attacks stainless steel; caustic soda attacks aluminium and some plastics. Vajra Industrial Solutions has deep expertise in chlor-alkali valve selection: PVDF-lined or titanium valves for chlorine, Hastelloy C-276 or rubber-lined valves for HCl, and SS316L or Alloy 20 for caustic service.
PVDF-Lined Butterfly Valve
Wet chlorine gas isolation - PVDF lining (or solid PVDF body) is uniquely resistant to wet Cl₂; titanium disc for highest corrosion resistance
Critical Requirements
- Wet chlorine gas - PVDF or PTFE-lined body, titanium disc; absolutely no iron, nickel-chromium alloys (attacked by wet Cl₂); no copper; FKM or PTFE packing only
- Dry chlorine gas (< 20 ppm moisture) - carbon steel is surprisingly acceptable for dry Cl₂; however most plants keep SS316 or titanium as standard
- Hydrochloric acid (all concentrations) - Hastelloy C-276 or titanium; SS316 only for dilute (<5%) cold HCl; NEVER use carbon steel
- Caustic soda (NaOH) - SS316L acceptable for <70% NaOH; avoid aluminium (catastrophic SCC in NaOH); EPDM diaphragm valves preferred for slurry-free NaOH
- Hydrogen gas from electrolysis - ATEX Zone 1; all electrical components on actuated valves must be Ex-certified
- Brine (saturated NaCl) - titanium or rubber-lined butterfly; SS316 not reliable above 60°C in concentrated chloride
Service Challenges
- Wet chlorine gas (Cl₂ + HCl + H₂O) - attacks iron, nickel alloys, and most stainless steels; requires PVDF or titanium wetted parts
- Hydrochloric acid (concentrated HCl) - one of the most aggressive mineral acids; Hastelloy C-276 or titanium required above 10%
- Caustic soda (50% NaOH, 80°C) - stress corrosion cracking in austenitic SS under tension; use CF3M (SS316L) cast body or duplex SS
- Chlorinated brine - combined attack of Cl₂ and NaCl; titanium is the only reliable general material
- Sodium hypochlorite (NaOCl) - unstable above 40°C; SS316L and CPVC; no rubber in contact (bleach attacks NBR/EPDM)
Vajra Butterfly Valves
Compact and efficient butterfly valves for large-scale flow control and isolation.
See the full Butterfly Valves rangeOther valves for chlor-alkali plants
Butterfly Valves for other applications
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