The electric worm gear carbon steel PTFE lined double flange butterfly valve D941F46 is a motorised isolation and throttling valve built for pipelines carrying aggressive acids, alkalis, solvents and other corrosive fluids where bare metal butterfly valves would fail within weeks. Manufactured by Trekre Valve, this double flange butterfly valve combines a WCB carbon steel pressure boundary with a continuous fluoroplastic lining across the body bore, disc faces and seat zone, while an electric actuator driving a two-stage worm gear reducer delivers reliable quarter-turn operation from a remote control room, DCS or PLC without manual handwheel effort on large bore lines.
Model D941F46 identifies an electrically actuated, flanged, centerline butterfly-valve configuration with F46 fluoroplastic lining designation. The double-flanged body provides integral flange connections for installation between compatible pipeline flanges. Because the butterfly disc remains within the flow passage when fully open, this conventional design must not be assumed suitable for pipeline pig passage. Any end-of-line or downstream piping-removal requirement must be supported by a documented rating for the exact valve configuration.
Electric worm gear carbon steel PTFE lined double flange butterfly valve construction
Connection type: double flange (FF or RF) per ANSI, DIN, JIS or GB standards
Structure: centerline disc with split or two-piece cast steel body and moulded fluoroplastic liner
Model designation: D941F46 (electric, flanged, centerline, PTFE/FEP/PFA lined)
Size range: 2″ to 48″ (DN50 to DN1200)
Pressure rating: PN6, PN10, PN16 and Class 150 (size and lining dependent)
Body material: WCB carbon steel, optional CF8/CF8M for external corrosion resistance
Lining options: PTFE, PFA, FEP or PO selected for media compatibility and permeation limits
Operation: electric actuator with two-stage worm gear reducer (electric valve gearbox); on-off or modulating
Control signal: AC220V / AC380V power; 4-20mA analog input for proportional positioning
Temperature range: -29°C to 150°C depending on lining grade and continuous exposure
Standards: GB/T 12238, API 609 Category A, HG/T 3704 lined valve specifications
Electric actuator and worm gear drive arrangement
Corrosive service valves on chemical headers, tank farms and wastewater treatment plants are often installed in locations where frequent manual operation is impractical or where interlocks with level, pressure or batch sequencing demand automated shut-off. The electric worm gear carbon steel PTFE lined double flange butterfly valve addresses both requirements by pairing a multi-turn or part-turn electric actuator with a secondary worm gear stage that multiplies output torque while providing self-locking hold at the closed or throttled position.
The electric actuator receives AC380V three-phase or AC220V single-phase supply depending on site power distribution. Internal motor control reverses rotation for open and close commands from hard-wired pushbuttons, contact closures or a distributed control system. For throttling and flow regulation duties, a 4-20mA analog position signal drives the actuator to hold the disc at intermediate angles, enabling proportional control on dilution lines, recirculation headers and neutralisation skids where a simple on-off valve would waste energy or upset batch chemistry.
The two-stage worm gear reducer — sometimes referred to as an electric valve gearbox in field documentation — sits between the actuator output and the valve stem. First-stage reduction from the actuator lowers speed and raises torque before the worm-and-worm-wheel pair engages the stem nut or stem key. That arrangement protects the fluoroplastic seat from impact closing while still delivering enough torque to compress the lined disc against the seat on larger diameters where handwheel effort would be excessive. Gear housings are sealed against moisture and dust for outdoor tank dike and pipe rack installations.
Limit switches, torque switches and position feedback potentiometers or encoders can be integrated so the DCS receives open, closed and fault status together with actual disc angle on modulating applications. Local handwheel override on the gear unit allows manual positioning during commissioning or power outage when plant procedures permit.
Fluoroplastic lining technology and corrosion barrier
Corrosive services attack valve bodies from the inside out. In an electric PTFE lined double flange butterfly valve, the fluoropolymer layer forms a continuous barrier between the flowing medium and all wetted steel surfaces including the body channel, disc edges and seat lands. PTFE provides broad chemical inertness against strong mineral acids and caustic solutions at moderate temperatures. PFA and FEP variants offer improved permeation resistance and smoother surfaces for sticky polymers or ultra-pure pharmaceutical fluids where extractables must be minimised.
The lining is moulded or bonded under controlled factory conditions rather than applied as a field wrap, ensuring uniform thickness at flange transitions where differential expansion during thermal cycling could otherwise stress a thin coating. Disc and body linings are profiled so the disc seal line compresses against the lined seat without exposing bare metal, maintaining bubble-tight shut-off on hydrochloric acid dilution, sodium hydroxide circulation, chlorine dioxide bleach and mixed solvent recovery lines typical in chemical plants served by Trekre Valve products.
External environmental corrosion is addressed separately through paint systems on the WCB shell or through CF8/CF8M body selection for coastal, offshore or outdoor installations. The double flange format keeps flange gasket faces outside the lined bore, allowing standard spiral-wound or PTFE envelope gaskets while the valve interior remains fully protected by fluoroplastic.
Double flange connection advantages over wafer designs
Wafer and double-flanged butterfly valves differ in body connection and flange-bolting arrangement. A double-flanged connection does not, by itself, establish dead-end pressure capability or authorize removal of downstream piping while the upstream side remains pressurized. Any such duty must follow the documented rating and installation requirements of the exact valve. For replacement projects, verify the face-to-face dimensions, flange drilling and lining arrangement against the existing piping specification.
On larger bore chemical headers where the electric worm gear carbon steel PTFE lined double flange butterfly valve is specified, flanged ends also simplify alignment with companion flanges on pumps, heat exchangers and static mixers. The motorised operator adds height above the pipeline centreline; double flange bodies with standard face-to-face lengths allow sufficient clearance for actuator maintenance while keeping the valve axis co-linear with the pipe run.
Typical applications and industry sectors
Electric PTFE lined double flange butterfly valves D941F46 are widely applied on sulphuric acid dilution, phosphoric acid transfer, caustic soda circulation, brine and chlor-alkali lines, pesticide formulation, electroplating rinse water, pulp bleaching stages and municipal wastewater disinfection circuits. Pharmaceutical and food-grade installations specify PFA lining where FDA or USP extractable limits apply, while general chemical plants often select PTFE or FEP based on temperature and permeation data for the specific solvent blend.
Power plant FGD scrubber recycle lines, semiconductor wet bench chemical distribution and battery material slurry handling also benefit from the combination of electric remote operation and fluoroplastic corrosion resistance. Because the valve closes against lined seats rather than bare metal, operators avoid the galling and leakage common on unlined steel butterfly valves cycled in acid service.
Selection and commissioning notes
When specifying an electric worm gear carbon steel PTFE lined double flange butterfly valve, confirm media composition, temperature, pressure class, flange standard and required control mode (on-off versus modulating). Actuator torque must exceed the calculated operating torque of the lined valve at maximum differential pressure, including safety margin for aged gaskets and line scaling. Voltage, enclosure rating (IP65 or higher for outdoor chemical areas) and explosion-proof classification where hazardous atmospheres exist should be documented on the data sheet.
Installation follows standard flange bolting practice with gaskets compatible with the chemical service. Electric wiring and 4-20mA signal cables are routed separately from high-voltage power per local electrical codes. After mounting, stroke the valve through full open and closed positions under no-flow conditions, verify limit switch feedback and tune control loop gain before introducing process fluid. Trekre Valve factory tests each lined butterfly valve for seat leakage and actuator function prior to shipment from our Wuxi manufacturing facility.
Product parameters summary
Valve type: electric worm gear carbon steel PTFE lined double flange butterfly valve
Model: D941F46
End connection: double flange RF/FF
Body: WCB / CF8 / CF8M
Lining: PTFE, PFA, FEP, PO
Disc: lined stainless steel or ductile iron with fluoroplastic overlay
Seat: moulded fluoroplastic integral with body liner
Actuator: electric multi-turn or part-turn with worm gear reducer
Control: AC220V / AC380V; 4-20mA modulating optional
Size: DN50–DN1200 (2″–48″)
Pressure: PN6–PN16, Class 150
Temperature: -29°C to +150°C (lining dependent)
Applicable media: acids, alkalis, solvents, chlorine compounds, wastewater and corrosive process fluids
Frequently Asked Questions
What electrical supply and control information do you need for D941F46?
Provide the available supply, on-off or modulating duty, required signals and operating environment. Ask for confirmation of the selected motor, gearbox and control equipment; the model name alone does not define the complete electrical package.
How do I confirm the actual lining rather than relying on the model suffix?
Request the exact lining grade and wetted-parts specification for the quoted assembly. Provide the medium and operating conditions and do not treat different fluoropolymer names in a series description as interchangeable.
Will manual operation be available if electrical power is lost?
State the required local operating and failure-response arrangements in the inquiry. Request confirmation of any manual override and its approved use; electric worm-gear operation alone does not establish a particular loss-of-power response.