China Butterfly Valve Flange End & Double Flange Type Factory Direct

Structural Rigidity & Flange Geometry

Unlike wafer or lug bodies clamped strictly by tie-rods, the double flanged butterfly valve integrates independent bolt circles on both the upstream and downstream faces. Built strictly to ISO 5752 Series 13 (short pattern) and Series 14 (long pattern), as well as EN 558 series specifications, this architecture eliminates pipe tensile stress transmission to the valve body, safeguarding internal seal alignment even during profound thermal cycling or ground settling.

• Direct bolting to standard ANSI B16.5, EN 1092-2, JIS B2239 flanges
• Unconditional bi-directional dead-end service capability
• Elimination of stud tension relaxation risks in buried lines

Offset Mechanics: Double vs Triple Eccentric

Double flanged bodies accommodate advanced offset geometries. While concentric designs rely on continuous rubber interference, our double eccentric (double offset) geometry lifts the disc from the seat within 10-15 degrees of opening, virtually eliminating friction-induced elastomeric degradation. For extreme thermal or chemical environments, triple eccentric metal-seated configurations utilize a conical sealing profile providing stellite-on-laminated stainless zero-leakage closure under API 607 fire-safe testing.

• Concentric vulcanized seat: Low pressure municipal distribution
• Double offset: Chilled water, cooling towers, low operating torque
• Triple offset: Power plant steam, hydrocarbons, harsh media

Hydrodynamic Profile & Cavitation Mitigation

Computational Fluid Dynamics (CFD) guided disc profiles minimize boundary layer separation and downstream eddy formation. By engineering streamlined lens-type contoured discs in Ductile Iron (EN-GJS-450-10) and CF8M stainless steel, ZFA double flanged butterfly valves achieve exceptional flow coefficients (Cv values) while suppressing localized vapor pocket collapse that leads to cavitation erosion in pump throttling service.

• Optimized hydrodynamic disc contouring with low head loss
• Heavy wall body design absorbing pipe vibration harmonics
• Multi-bushing shaft support preventing shaft deflection

Water Works & Desalination

For high-capacity intake stations and reverse osmosis networks, ZFA double flanged butterfly valves with aluminum bronze (C95800) or Duplex SS 2205 discs prevent chloride crevice corrosion and pitting while delivering drip-tight bi-directional isolation.

Centralized HVAC & District Cooling

Designed with standard ISO 5211 actuator mounting flanges, our double flanged and lug valves link seamlessly with Modbus/BACnet multi-turn electric and pneumatic rack-and-pinion actuators for precise chilled water loop balancing and energy conservation.

Aggressive Chemicals & Mining Slurry

Employing heavy split-body architectures lined with compression-molded virgin PTFE/PFA, these valves protect metallic components from highly reactive acids and alkaline lyes, preventing fugitive stem emissions via live-loaded Belleville washer packing systems.

Thermal Power & Steam Systems

Metal-seated double flanged triple offset butterfly valves deliver friction-free non-rubbing quarter-turn isolation up to 450°C. Stellite welded seats resist high-velocity steam wire-drawing and particulate abrasive scouring in condensate recovery lines.

IIoT Sensorization & Predictive Maintenance

Next-generation double flanged butterfly valves increasingly integrate wireless vibration, acoustic emission, and stem travel sensors within the actuator bracket assembly. By analyzing continuous micro-fluctuations in operating torque and pressure drop telemetry, industrial plant operators can detect seat wear, scale accumulation, or stem binding weeks before catastrophic fluid loss occurs.

Fugitive Emission Control: ISO 15848-1

With global environmental regulations targeting fugitive methane, VOC, and greenhouse gas leakage, stem sealing geometries have evolved. ZFA incorporates dual live-loaded secondary O-rings with pure expanded graphite or low-friction virgin PTFE chevrons, delivering certified leakage compliance under ISO 15848-1 Class AH/BH standards even through 10,000 continuous thermal cycles.

Advanced Polymeric & Alloy Metallurgy

Meeting hydrogen transport, super-critical water, and zero-carbon energy targets demands extreme metallurgy. Our R&D pipeline expands ceramic-coated discs (plasma-sprayed chromium oxide) and Hastelloy C-276 trim options that withstand localized pitting at high chloride concentrations and high pH fluctuations where conventional austenitic stainless grades rapidly deteriorate.