Chemical Processing×Butterfly Valves

Butterfly Valves for Chemical Processing

Butterfly valves in chemical processing cover a wide range — from large-bore cooling water and utility service to PTFE-lined and Hastelloy designs for corrosive acid and solvent isolation. Vajra Industrial Solutions supplies rubber-seated, PTFE-seated, and triple-offset metal-seated butterfly valves in SS 316L, Hastelloy C-276, and PTFE/PFA-lined configurations for chemical plant service, with fire-safe design, ISO 15848 fugitive emission compliance, and full actuation packages for DCS-controlled isolation.

Key Applications — Butterfly Valves in Chemical Processing

Cooling Water and Utility Services

Ductile iron or carbon steel butterfly valves with EPDM or NBR seats for cooling water, tempered water, and plant utility services (process water, fire water, instrument air header). Large bore (DN300–DN900) butterfly valves at fraction of gate valve cost. Electric or pneumatic actuator for remote SCADA isolation.

DN100–DN900, PN 10–16, Ductile Iron / CS, EPDM seat, electric actuator, EN 593

Acid and Alkali — PTFE/PFA-Lined Butterfly Valves

PTFE-lined butterfly valves for concentrated sulfuric acid, hydrochloric acid, phosphoric acid, and caustic streams. PTFE lining covers both body and disc for full chemical protection. PFA-lined versions for higher purity and temperature applications. Full-face PTFE seat ensures zero metal contact with fluid. Suitable for pH 0–14 across most common industrial chemicals.

DN25–DN300, PN 6–16, CS body with full PTFE/PFA lining, wafer or lug, EN 593

Chlorine and Corrosive Gas Vent Headers

PTFE-lined butterfly valves for chlorine gas vent headers, HCl acid gas, and SO₂/SO₃ absorption tower isolation. PTFE seat and liner provides complete corrosion protection. Low torque PTFE-seated design allows smaller actuator. Specify with leak-off connection on shaft sealing for toxic gas containment verification.

DN50–DN300, PN 6–10, CS body / PTFE liner, PTFE seat, chlorine and acid gas service

Solvent Storage and Transfer — Hastelloy

Triple-offset metal-seated butterfly valves in Hastelloy C-276 body and disc for hot corrosive solvents, mixed acid streams, and aggressive chemical reactor effluents. Metal-to-metal seal eliminates elastomer compatibility concerns. Anti-static, fire-safe, ISO 15848 fugitive emission Class A for VOC-regulated service.

DN100–DN400, Class 150–300, Hastelloy C-276, metal seat, API 609, ISO 15848 Class A

Required Certifications

EN 593 — Industrial butterfly valvesAPI 609 — Petroleum and natural gas industries butterfly valvesISO 15848-1 — Fugitive emissions (toxic and VOC chemical service)API 607 — Fire-safe testing (flammable chemical service)EN 10204 3.1 MTCs with PMIATEX / IECEx — Actuators in hazardous area zones

Recommended Materials

CS body + PTFE/PFA full lining — mineral acids, caustic soda, oxidising chemicals
A351 CF8M (SS 316L) — dilute acids, alkalis, solvents, cooling water
Hastelloy C-276 (N10276) body and disc — concentrated acids, hot solvents, mixed acid
PTFE seat — universal chemical resistance for most acids/alkalis; replace elastomers
EPDM seat — cooling water, steam, dilute alkali
Metal seat (Stellite or Hastelloy overlay) — high-temperature chemical service >200°C

Selection Factors

Lining vs alloy: PTFE-lined CS is cheaper for acid/alkali at <150°C; solid Hastelloy required above 150°C or for erosive/abrasive chemical streams
Seat type: PTFE (corrosion resistant, chemical service); EPDM (cooling water, steam, wide temperature range); metal (high-temp, fire-safe, solvent-swelling risk)
Mounting: Wafer for in-line chemical; lug for end-of-line with downstream flange removal; double-flanged for high-torque large-bore chemical
Fugitive emissions: ISO 15848 Class A required for toxic solvents and regulated VOCs
Anti-static: Required for flammable solvent service — ensure disc-to-body earthing continuity through SS disc shaft seal
Actuator sizing: PTFE-lined valves have higher torque at end-of-travel than elastomer-seated — verify actuator output factor ≥1.5×

Technical FAQs

Can PTFE-lined butterfly valves handle all acids?
PTFE itself resists virtually all acids including fuming sulfuric, concentrated HCl, HF, and chlorosulfuric acid. The limitation is the carbon steel body — if any permeation through the PTFE liner reaches the steel substrate, corrosion will occur. Permeation rate increases significantly above 120°C and in highly concentrated acids. For service above 120°C or for fluorinating acids (HF) where permeation is a concern, use solid fluoropolymer (PFA) lining or a solid Hastelloy butterfly valve. PTFE-lined butterfly valves are excellent for ambient-to-moderate-temperature chemical service across the pH 0–14 range.
What is the difference between a wafer and a lug butterfly valve?
A wafer butterfly valve is sandwiched between two flanges with through-bolts — it cannot support a pipeline on either side independently. A lug butterfly valve has threaded inserts (lugs) in the body flange — bolts go into the lugs rather than through them. This allows one side of the pipeline to be disconnected while the valve remains bolted in place on the other side. For chemical plant service, lug butterfly valves are recommended wherever the valve may be used as a dead-end isolation point, such as tank outlet isolation or equipment maintenance points.

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Butterfly Valves for Chemical Processing

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