Cast Steel Lined PTFE Worm Gear Double Flange Butterfly Valve D341F46 Overview
The cast steel lined PTFE worm gear double flange butterfly valve D341F46 is a manual isolation valve for corrosive process lines where a carbon steel pressure shell and full fluoroplastic wetted surfaces are required in a double-flanged body pattern. Manufactured by Trekre Valve, this cast steel lined butterfly valve combines a WCB body with moulded PTFE, PFA or FEP lining on the bore, disc faces and seat lands, plus a worm gear reduction drive for controlled 90-degree rotation. The double-flange ends bolt directly to pipeline flanges on both sides, providing stable retention for horizontal and vertical runs on chemical transfer headers, tank farm manifolds and acid-alkali circulation systems.
Construction and design features
- Connection type: double flange (RF or FF per project standard; bolted to pipeline flanges on both ends)
- Structure: centerline disc with two-piece cast steel body and continuous fluoroplastic lining on bore, disc faces and seat lands
- Size range: 2″ to 48″ (DN50 to DN1200) for standard double-flange patterns; confirm face-to-face per GB/T 12238 or project drawing
- Pressure rating: PN10, PN16 and PN25; Class 150 on ANSI flange pairs (size and lining grade dependent)
- Body material: cast carbon steel WCB with external paint or epoxy coating for general industrial environments
- Lining options: PTFE, PFA or FEP selected for media compatibility, permeation resistance and temperature duty
- Operation: worm gear handwheel with self-locking reduction for controlled opening and closing torque
- Temperature range: -29°C to 180°C depending on lining material and continuous exposure conditions
- Standards: GB/T 12238, HG/T 3704 lined valve specifications, API 609 Category A where applicable
Cast steel body with fluoroplastic corrosion barrier
Corrosive services attack valve internals from the bore outward while ambient humidity and wash-down chemicals can attack external steel surfaces on poorly specified valves. In this cast steel lined PTFE worm gear double flange butterfly valve, the WCB body provides structural strength for flange bolt loads and pipeline dead-end thrust at a lower material cost than stainless equivalents, while PTFE, PFA or FEP forms a continuous barrier between the flowing fluid and all wetted steel surfaces including the body channel, disc faces and seat ring.
PTFE offers broad chemical inertness against strong mineral acids, caustic solutions and mixed solvents at moderate temperature. PFA provides improved permeation resistance and smoother surfaces for sticky polymers, chlorinated compounds or process fluids where trace metal contamination must be avoided. FEP suits applications where melt-processed lining uniformity at flange transitions and gasket lands is critical. The lining is moulded under factory conditions rather than applied as a field wrap, ensuring uniform thickness where flange gaskets compress against the raised or flat faces.
Double flange connection and pipeline integration
Double-flange butterfly valves install with independent bolt sets on the upstream and downstream pipeline flanges. Unlike wafer patterns that rely on through-bolts spanning both flanges, the double-flange body carries its own bolt holes. Independent flange fasteners alone do not establish permission for end-of-line service or removal of an adjacent flange. Confirm the model-specific rating, installation instructions and approved isolation procedure before maintenance. This makes D341F46 pattern valves suitable for tank outlet isolation, pump suction and discharge headers, and vertical risers where pipeline loads must not transfer through a clamped wafer body alone.
Install the valve with the disc slightly open to protect lined seat edges during flange bolt-up. Use gaskets compatible with the chemical service — PTFE envelope, spiral wound or rubber bonded as specified on the data sheet. Tighten flange bolts in a star pattern to avoid seat distortion at the lined gasket faces. Trekre Valve confirms face-to-face dimension, bolt circle, flange facing type and gasket seating width against ANSI, DIN, JIS or GB standards before shipment from our Wuxi manufacturing facility.
Worm gear drive and operating torque
Large bore lined butterfly valves require significant breakaway torque to unseat the fluoroplastic seal line after periods in the closed position, especially when line pressure or media deposits add friction. A worm gear reduction mounted on the stem converts moderate handwheel effort into the torque needed to rotate the disc through 90 degrees without sudden jerking that could damage the lining at the seat edge.
The self-locking worm gear prevents back-driving from line torque on partially open valves in high-velocity services. Handwheel direction, open and closed position stops, and optional mechanical position indicator are factory-set and documented on the nameplate. For buried or hard-to-reach installations, extension stem and floor box options can be quoted separately. Operating torque tables in the project submittal include breakaway and running values at rated differential pressure with margin for aged gaskets and scale buildup.
Fluoroplastic lining selection for PTFE, PFA and FEP duty
When the process specification names PFA or FEP rather than standard PTFE, the choice usually reflects temperature margin, permeation limits or surface finish requirements rather than a generic corrosion label. For hot corrosive condensate, mixed acid streams or chlorinated solvents, confirm chemical compatibility and permeation limits using data for the actual lining grade, complete lining construction and operating conditions. A polymer name alone does not establish long-term permeation performance or a universal preference for PFA over PTFE. FEP lining suits lower-temperature acid transfer and caustic circulation where melt-processed uniformity at the flange gasket lands simplifies field assembly.
The disc seal line engages the lined seat without exposing bare metal, maintaining shut-off performance per project leakage criteria documented in the test report. Do not use the valve for throttling service beyond the partial-open limits defined on the data sheet — lined centerline discs are intended primarily for on-off isolation.
Typical applications and industry sectors
Chemical plants deploy cast steel WCB lined PTFE double flange butterfly valves on sulphuric acid transfer, hydrochloric acid dilution headers, phosphoric acid circulation and solvent recovery manifolds where corrosive fluids demand fluoroplastic protection with stable flange retention. Chlor-alkali facilities isolate brine, caustic and chlorine compound streams on horizontal and vertical runs where painted WCB external surfaces suit indoor or sheltered outdoor installations.
Water and wastewater treatment facilities use lined double flange butterfly valves on sodium hypochlorite dosing, ferric chloride feed and polymer injection headers. Pulp and paper bleaching stage shutoff, metal finishing acid rinse lines and fertilizer plant acid handling are additional sectors where double-flange mounting and worm gear manual operation replace bare steel valves that would corrode within months. Power plant FGD scrubber recycle isolation and general industrial acid-alkali piping also specify D341F46 pattern valves when cost-effective carbon steel shells with full lining are acceptable for the external environment.
Installation, maintenance and inspection
After installation, cycle the valve fully open and closed under no-flow conditions to verify smooth worm gear operation and correct disc orientation. Introduce process fluid gradually and inspect flange joints and stem packing for leakage. Periodic maintenance includes handwheel lubrication per site procedure, stem packing adjustment if needed, and visual inspection of external paint where wash-down chemicals are used.
Store spare lined double flange valves with the disc in the slightly open position to avoid permanent seat compression set during long warehouse periods. Before returning a valve to service after extended storage, inspect gasket faces for lining damage at bolt holes and verify worm gear backlash remains within factory tolerance. Avoid steam cleaning above the lining temperature limit specified on the nameplate.
Selection and ordering information
When specifying this cast steel lined PTFE double flange butterfly valve, provide medium name and concentration, design temperature and pressure, nominal size, flange standard (ANSI, DIN, JIS or GB), lining material preference (PTFE, PFA or FEP), flange facing type, and any extension stem or gear box orientation requirements. Confirm whether the installation requires dead-end service rating on one flange side. Trekre Valve factory tests each lined butterfly valve for seat leakage and handwheel operation prior to shipment.
Product parameters summary
- Valve type: cast steel WCB lined PTFE worm gear double flange butterfly valve D341F46
- End connection: double flange (RF/FF per standard)
- Body: cast carbon steel WCB
- Lining: PTFE, PFA, FEP
- Disc: lined steel with fluoroplastic overlay
- Seat: moulded fluoroplastic integral with body liner
- Actuator: worm gear handwheel, self-locking
- Size: DN50–DN1200 (2″–48″)
- Pressure: PN10 / PN16 / PN25; Class 150
- Temperature: -29°C to +180°C (lining dependent)
- Applicable media: acids, alkalis, solvents, chlorine compounds, wastewater and corrosive process fluids
- Manufacturing: Trekre Valve, Wuxi, China
Frequently Asked Questions
What dimensions should I compare before ordering the D341F46 double-flanged valve?
Provide the required size, companion flange details, facing and face-to-face length. Request the selected assembly drawing, including gearbox clearance, rather than using the dimensions of a wafer-style lined valve.
Should I add a separate gasket against the lined flange face?
Obtain the approved installation arrangement for the exact valve lining and companion flanges. Do not apply a universal add-gasket or no-gasket rule without the model-specific instructions.
Which documents should confirm the lining and materials for my order?
Ask for the order datasheet or technical agreement identifying the actual body, lining, disc and seals, with the relevant drawing and inspection requirements. Check those documents against the intended medium and operating conditions before approval.