The PTFE PFA FEP lined lug type butterfly valve is a corrosion-resistant quarter-turn isolation valve for acid, alkali, chlorine, brine, chemical solvent and wastewater pipelines where metal wetted surfaces would fail within months. Manufactured by Trekre Valve in Wuxi, China, this lug-style butterfly valve uses a two-piece split body with integrally moulded fluoropolymer lining on the body bore and disc contact surfaces so process media touches only PTFE, PFA or FEP — not cast iron or carbon steel. Handle lever, worm gear, pneumatic actuator and electric actuator configurations share the same lined disc and seat geometry, allowing operators to match drive type to torque, access and automation requirements without changing the corrosion barrier.
Lug butterfly valves install between companion flanges using the fastener arrangement specified for the actual lug drilling and flange standard. Dead-end or single-flange service must only be used where the exact valve size, lug pattern and seat-retention design have a documented rating for that configuration. Trekre supplies full-lining and semi-lining variants: full lining covers both body bore and disc with fluoropolymer; semi-lining leaves the disc in stainless steel 304 or 316 while the body bore remains fully lined for cost-sensitive duties where disc abrasion is low. The two-piece body clamps the moulded liner between halves under controlled bolt torque, preventing liner creep and extrusion at flange faces during thermal cycling between -29°C and 180°C depending on fluoropolymer grade.
PTFE PFA FEP lined lug type butterfly valve construction
Connection type: lug type (semi-lug or full lug ears per ASME B16.5 / EN 1092-1 drilling)
Structure: centric disc butterfly valve with split body and moulded fluoropolymer liner
Size range: DN40 to DN600 (NPS 1-1/2″ to 24″)
Pressure rating: PN10, PN16; ANSI Class 150 where cross-referenced
Body material: grey cast iron GG25/GGG40, carbon steel WCB with full fluoropolymer lining, optional stainless steel CF8 shell
Lining material: PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy), FEP (fluorinated ethylene propylene), optional PCTFE or PO on request
Disc: fully lined PTFE/PFA/FEP disc, or stainless steel 304/316 disc with body-side lining only (semi-lining)
Seat: moulded integral liner seat with SI rubber elastic backup gasket for zero-leakage shut-off
Stem: stainless steel 304/316 rising or non-rising stem with two-piece stem seal and anti-blowout retention
Operation: handle lever (DN40–DN200), worm gear manual (DN50–DN600), pneumatic double-acting or spring-return, electric on-off or modulating
Design standard: GB/T 12238, API 609 Category A, HG/T 3704 lined butterfly valve where applicable
End connection: lug ears to ASME B16.5 Class 150, EN 1092-1 PN10/PN16, JIS B2220 10K/16K
Face-to-face: ISO 5752 Series 20, EN 558, API 609 short pattern
Testing: GB/T 13927, API 598, bubble-tight seat test on clean water or air per lining temperature limit
Temperature range: -29°C to 180°C (PTFE), -29°C to 200°C (PFA), -29°C to 150°C (FEP) — confirm per medium and cycle duty
Fluoropolymer lining grades and media compatibility
PTFE lining offers broad chemical inertness across strong acids including hydrochloric, sulphuric and nitric acid dilutions, caustic soda, hypochlorite bleach and organic solvents. The material withstands long-term service from -180°C to 260°C in laboratory conditions; in valve applications Trekre rates PTFE-lined lug valves to 180°C continuous with de-rating for cyclic thermal shock. Low surface energy resists fouling on viscous slurries and polymerisation-prone monomers, making PTFE the default lining for multipurpose chemical headers and bulk acid transfer manifolds.
PFA lining shares PTFE chemical resistance with improved melt-processability and stronger adhesion to the metal substrate, reducing the risk of liner voids behind the moulded surface on complex lug body geometries. PFA suits higher-temperature acid regeneration loops, bromine handling and pharmaceutical clean-in-place circuits where extractables must stay minimal. FEP lining provides a smoother moulded finish and excellent permeation resistance on chlorine wet gas and hydrofluoric acid duties at moderate temperature; FEP is selected when customers require enhanced weld-free liner continuity across the body split line.
Full lining means both body bore and disc wetted surfaces are fluoropolymer, so no metal contact occurs anywhere the medium flows during the closed or throttled position. Semi-lining retains a stainless disc for abrasive slurries where fluoropolymer on the disc would wear quickly, while the body bore remains fully protected against pipeline corrosion. Trekre moulds liners under controlled temperature and pressure, then machines the liner face at the flange sealing surface to maintain flatness for gasket compression without exposing bare metal at the flange joint.
Four-stage sealing and lug end installation
The valve employs a four-stage sealing arrangement: primary fluoropolymer disc-to-liner contact, secondary SI rubber elastic seat backup, stem packing with adjustable gland, and body joint gasket between split halves. This layered design achieves bubble-tight shut-off on water test per API 598 while accommodating liner thermal expansion without tearing the moulded seat ring. If downstream piping removal or single-flange operation is required, use only the fastener arrangement and pressure rating documented for the exact lined lug-valve configuration; do not infer that capability from the lug body style alone.
Handle-operated models use a locking lever with notch positions at 0°, 45° and 90° for quick visual indication; worm gear versions include self-locking reduction for larger diameters where hand torque exceeds operator limits. Pneumatic and electric packages mount to ISO 5211 top flanges on the same body, preserving the lined wetted path regardless of automation upgrade. Trekre verifies actuator torque against calculated disc torque including liner friction factors so actuators do not over-compress the soft seat during end-of-travel seating.
Applicable working conditions and industries
PTFE PFA FEP lined lug butterfly valves serve chlor-alkali brine lines, sulphuric acid pickling, phosphoric acid fertiliser production, electroplating rinse water, pulp bleaching stages, semiconductor wet bench chemical supply, municipal wastewater with hypochlorite dosing, and pharmaceutical ingredient transfer. The lug body fits between existing flange pairs without pipeline spreaders on many retrofits, reducing downtime when replacing failed rubber-lined or unlined valves in corrosive headers. Full fluoropolymer contact prevents iron ion contamination in high-purity chemical batches where even trace metal leaching affects product quality.
Semi-lined stainless disc variants handle mild abrasion from lime slurry or catalyst fines while the body bore resists the bulk acid carrier. Worm gear and actuator options integrate with plant DCS for remote isolation during leak detection or batch changeover. Trekre supplies material certificates for body metal, lining resin batch traceability, hydrostatic shell test reports and seat leakage records for project quality files.
Product parameters summary
Model series: PTFE PFA FEP lined lug type butterfly valve
Nominal diameter: DN40–DN600 (NPS 1-1/2″–24″)
Nominal pressure: PN10/PN16, Class 150
Body: GG25, GGG40, WCB with PTFE/PFA/FEP lining; CF8 shell optional
Lining: PTFE, PFA, FEP full or semi-lining
Drive: handle lever, worm gear, pneumatic, electric
Standards: GB/T 12238, API 609, HG/T 3704, EN 593
Leakage class: API 598 Rate A on seat, zero visible leakage on shell
Selection and ordering checklist
Confirm medium composition and concentration, design temperature and pressure, nominal diameter, flange standard and drilling pattern, lining grade (PTFE, PFA or FEP), full or semi-lining requirement, drive type and required operating torque, seal direction if unidirectional duty, and whether the valve must comply with a project inspection and test plan. Provide pipeline orientation and clearance for handle or gear operator swing. Trekre Valve engineers confirm liner grade, body material and actuator sizing from your duty sheet before production release. Request a quotation with complete process data and receive technical datasheets, lining material certificates and test reports suitable for EPC approval packages.
For distributors and equipment manufacturers sourcing corrosion-resistant isolation valves from China, this PTFE PFA FEP lined lug type butterfly valve delivers reliable shut-off on aggressive media where metal-seated or unlined designs cannot meet service life expectations. Contact Trekre with your application details to confirm lining selection, lug drilling and drive configuration matched to your pipeline specification.
Frequently Asked Questions
Which parts remain exposed to the fluid in the semi-lined version?
The page distinguishes a lined disc from a stainless-steel disc alternative. Ask for the exact wetted-parts specification and coverage drawing so the body lining, disc and seals can be checked against your medium.
Should I request a handle or a worm gearbox for this lug valve?
Provide the selected size, operating conditions, required duty and available access space. Ask for the operating requirements of the actual configuration rather than assuming one manual drive suits every size and lining option.
Is a single upstream flange enough for maintenance isolation?
Only where the exact valve configuration has a documented single-flange rating and approved bolting arrangement. Request those details before planning downstream removal; the lug-body description alone does not establish this service.