Wafer Butterfly Valve PTFE + Silicon Seat
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Corrosion-Resistant Wafer Butterfly Valve — WCB Body with PTFE Liner and SS316 PFA-Coated Disc
This corrosion-resistant wafer butterfly valve is the most chemically resistant variant of the WCB corrosion-resistant family. The WCB body is protected by a continuous PTFE liner that completely covers the interior and forms the sealing seat — just like in the other variants. The decisive difference lies in the disc: instead of the conventional PTFE coating, the SS316 disc has a PFA (Perfluoroalkoxy) coating, the fluoropolymer with the highest chemical resistance available for fusion-applied linings.
The PFA on the disc offers two specific advantages over conventional PTFE: its injection molding application creates a coating without penetration lines or porosity, and its greater resistance to extremely oxidizing fluids and high-concentration acids makes it the first choice when the conventional PTFE of the disc might be attacked by the fluid in continuous service.
PFA vs. PTFE in Disc Coating — Why It Matters
Although both are fluoropolymers with exceptional chemical resistance, PFA surpasses PTFE in the valve disc for two reasons:
- No penetration lines: PTFE is applied as a machined solid piece or as a coating with potential bond lines. PFA is fusion-applied, creating a continuous barrier completely impermeable to the fluid — even against highly aggressive fluids that would penetrate PTFE through its microscopic bonds in prolonged service.
- Greater resistance to strong oxidizers: PFA resists oxidizers such as chlorine dioxide (ClO₂), concentrated hydrogen peroxide, and fuming nitric acid that can degrade conventional PTFE in the long term.
Construction Materials
- Body: Carbon steel WCB — mechanical support structure with no fluid contact
- Internal Liner: Continuous molded PTFE — protects the body and forms the sealing seat
- Disc: SS316 stainless steel with fusion-applied PFA coating — no penetration lines, no metal-fluid contact
- Shaft / Stem: SS316 stainless steel with PTFE seals
Technical Specifications
- Mounting Type: Wafer — between DIN PN10/16 or ANSI 150 flanges
- Nominal Pressure: PN10 / PN16
- Operating Temperature: -20 °C to +150 °C
- Available Diameters: DN50 (2") to DN400 (16")
- Design Standard: EN 593
- Actuator Interface: ISO 5211
Compatible Fluids — The Widest Range in the WCB Corrosion-Resistant Family
- ✅ Sulfuric acid H₂SO₄ up to 50%
- ✅ Hydrochloric acid HCl up to 37%
- ✅ Nitric acid HNO₃ up to 40%
- ✅ Phosphoric acid H₃PO₄ — any concentration
- ✅ Caustic soda NaOH up to 50%
- ✅ Sodium hypochlorite NaClO up to 20%
- ✅ Chlorine dioxide ClO₂ in bleaching concentrations (paper industry)
- ✅ Hydrogen peroxide H₂O₂ up to 30%
- ✅ Ferric chloride FeCl₃ — any concentration
- ✅ Seawater and concentrated brines
- ✅ Organic solvents of low to medium aggressiveness
- ⚠️ HF at any concentration, H₂SO₄ >70%, H₂O₂ >30%: use PFA corrosion-resistant ball valve →
Full Comparison — WCB Corrosion-Resistant Butterfly Valve Family
| Variant | Disc | Disc Chemical Resistance | Best For |
|---|---|---|---|
| WCB + PTFE liner, SS316 disc | SS316 uncoated | Medium — SS316 exposed to fluid | Diluted acids and alkalis where SS316 is sufficient |
| WCB + PTFE liner, SS316 + PTFE disc | SS316 PTFE-coated | High — zero metal-fluid contact | Fluids that attack SS316 — high chlorides, moderate oxidizers |
| WCB + PTFE liner, SS316 + PFA disc ← This one | SS316 PFA-coated | Maximum — PFA with no penetration lines | ClO₂, concentrated H₂O₂, higher concentration acids, demanding continuous service |
Available Operation Versions
- Manual with Lever: DN50 to DN150
- Manual with Gear Reducer: DN200 to DN400
- With Pneumatic Actuator: Single-acting NC or NO, double-acting. ISO 5211 + NAMUR. For environments with aggressive acid vapors, specify actuator with high chemical resistance epoxy coating or SS316 casing.
- With Electric Actuator: 24 VDC, 110 VAC, 220 VAC. ON/OFF or modulating 4–20 mA.
For the complete range of corrosion-resistant valves, see corrosion-resistant butterfly valves category →