Worm Gear Lug Type Steel Lined PTFE Butterfly Valve LTD371F46
The worm gear lug type steel lined PTFE butterfly valve LTD371F46 is a manual isolation valve for corrosive process lines where fluoroplastic lining, lug-body installation and worm gear operation are specified. Manufactured by Trekre Valve, this fluorine-lined lug butterfly valve combines a carbon steel WCB pressure shell with a PTFE, PFA or FEP wetted barrier, worm gear reduction drive and lug ears for the bolting arrangement shown on the approved valve drawing. Any dead-end or single-flange requirement must be confirmed from the documented rating for the exact valve size and configuration.
Construction and design features
Connection type: lug type (semi-lug or full lug pattern with threaded ears on the body periphery)
Structure: centerline disc with two-piece carbon steel body and continuous fluoroplastic lining on bore, disc faces and seat lands
Size range: 2″ to 24″ (DN50 to DN600) for standard lug patterns; larger sizes available on project request
Pressure rating: PN10 and PN16; Class 150 on ANSI flange pairs (size and lining grade dependent)
Body material: carbon steel WCB cast body with external paint system 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 150°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
Lug type versus wafer installation
Wafer and lug butterfly valves use different body and flange-bolting arrangements. The actual lug-hole pattern, thread engagement and fastener arrangement must follow the approved product drawing and companion flange standard. If an installation requires downstream piping removal or single-flange operation, the exact valve size and configuration must have a documented dead-end or single-flange pressure rating, and maintenance must follow the approved isolation and depressurization procedure. Do not infer safe pressure retention from the lug body style alone.
On branch connections, pump suction isolation and mixer feed headers, lug ears distribute clamping force more evenly around the valve periphery than wafer bodies that depend solely on flange gaskets for stability. The worm gear lug type steel lined PTFE butterfly valve LTD371F46 is specified where project engineers expect pipeline vibration from reciprocating pumps, intermittent slug flow or thermal expansion cycles that could shift a wafer valve out of alignment. Trekre Valve confirms lug ear thread size, bolt circle and face-to-face dimension against the flange standard on the data sheet before shipment.
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 and carbon steel body
Corrosive media attack valve internals from the bore outward. In this steel lined PTFE lug butterfly valve, 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 or ultra-pure pharmaceutical fluids. FEP suits applications where melt-processed lining uniformity at flange transitions and lug ear passages is critical.
The WCB carbon steel body carries flange loads and external mechanical stress while the lining handles chemical duty inside the bore. Lining is moulded under factory conditions rather than applied as a field wrap, ensuring uniform thickness at lug ears and body edges where flange gaskets compress. 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.
Typical applications and industry sectors
Chemical plants deploy worm gear lug type steel lined PTFE butterfly valves on sulphuric acid transfer, hydrochloric acid dilution headers, phosphoric acid circulation and solvent recovery manifolds where corrosive fluids demand fluoroplastic protection and lug retention on vibrating pump lines. Chlor-alkali facilities isolate brine, caustic and chlorine compound streams with lined lug valves on vertical risers and dead-end sample connections.
Water and wastewater treatment facilities use lined lug butterfly valves on sodium hypochlorite dosing, ferric chloride feed and polymer injection headers connected to metering pumps that induce pipeline pulsation. Power plant FGD scrubber recycle isolation, pulp bleaching stage shutoff and metal finishing acid rinse lines are additional sectors where lug mounting and worm gear manual operation replace bare steel valves that would corrode within months.
Installation, maintenance and inspection
Install the valve with the disc positioned as required by the approved installation procedure to protect the lined seat and disc during flange assembly. Use the fastener arrangement specified for the actual lug drilling and companion flange standard, together with gaskets compatible with the selected chemical service. Tighten the flange fasteners evenly in the required sequence to avoid seat or body distortion, and align both pipeline sections before final torque so external piping loads are not imposed on the valve stem or body.
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. 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.
Selection and ordering information
When specifying the LTD371F46 lined lug butterfly valve, provide medium name and concentration, design temperature and pressure, nominal size, flange standard (ANSI, DIN, JIS or GB), lining material preference, lug ear bolt specification 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 from our Wuxi manufacturing facility.
Product parameters summary
Valve type: worm gear lug type steel lined PTFE butterfly valve LTD371F46
End connection: lug type (threaded ears for independent flange bolting)
Body: 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–DN600 (2″–24″)
Pressure: PN10 / PN16; Class 150
Temperature: -29°C to +150°C (lining dependent)
Applicable media: acids, alkalis, solvents, chlorine compounds, wastewater and corrosive process fluids
Manufacturing: Trekre Valve, Wuxi, China
Frequently Asked Questions
What lining will be supplied with the LTD371F46 valve I order?
Ask for the exact lining grade and wetted-parts specification on the order documents. The page lists different fluoropolymer alternatives; the complete selected configuration must be checked against the medium, concentration and operating conditions.
How do I check the lug fasteners before ordering a replacement?
Send the companion flange specification and existing installation details. Request the selected valve drawing showing lug drilling, thread or through-hole arrangement and the required fasteners rather than choosing bolts from the connection name alone.
What clearance is needed to operate and maintain the worm gearbox?
Provide the required installation orientation and nearby obstructions. Ask for the assembly dimensions and access requirements for the actual gearbox and valve size before finalizing the layout.