WCB High-Performance Butterfly Valve — Double Eccentricity, SS316 Disc, TFM1600/RPTFE Seat, ANSI 150 Class 150

The WCB high-performance butterfly valve with double eccentricity combines the double eccentricity geometry of the HP range — disc immediately separates from the seat upon opening, with no continuous sliding during the stroke — with a WCB carbon steel body, the lower-cost option for natural gas, LPG, steam, oil, and process fluid services where WCB body is the specified material and CF8M (SS316) represents an additional cost not justified by the fluid. The SS316 disc ensures corrosion resistance on the surface in contact with the fluid, and the TFM1600 or RPTFE seat provides tight sealing with a longer lifespan than conventional elastomers up to 180 °C.

WCB vs. CF8M in High-Performance Butterfly Valves — Same Geometry, Fluid-Optimized Materials

Double Eccentricity — Disc Does Not Touch the Seat During Stroke

Similar to the CF8M version, the double eccentricity geometry eliminates the continuous sliding between disc and seat that characterizes conventional butterfly valves:

• First eccentricity (axial): The axis of rotation is offset laterally from the seat plane — as it rotates, the disc immediately lifts off the seat at the start of opening and does not touch it again until the last instant of closing.
• Second eccentricity (radial): The axis is offset perpendicular to the pipe axis — reinforcing the lift-off effect and improving force distribution at final closure.
• Practical result: The TFM1600 or RPTFE seat only experiences wear at the final instant of closure — not during the entire 90° stroke as in conventional butterfly valves. The seat's lifespan increases proportionally compared to a butterfly valve with an EPDM or NBR elastomeric seat in gas and steam service.

TFM1600 and RPTFE Seat — Two High-Performance Fluoropolymer Options

TFM1600 — High-Density Modified PTFE

• Higher density and lower permeability than standard PTFE: Better sealing in low differential pressure gas service — critical in natural gas applications where even micro-leakage can be unacceptable.
• Lower creep (cold flow): Maintains sealing force for longer and over more operating cycles than conventional PTFE under load and temperature.
• Universal chemical resistance: Compatible with natural gas, LPG, steam, oil, and virtually any industrial fluid up to 180 °C.
• First choice for: Natural gas, LPG, clean steam, oil, and dry process fluids where maximum tightness is the primary requirement.

RPTFE — Reinforced PTFE

• Higher surface hardness than virgin PTFE: Reinforcement (typically fiberglass or carbon fiber) increases seat hardness — greater resistance to abrasive wear in fluids with fine suspended particles.
• Lower deformation under load: Less tendency to creep than virgin PTFE, especially in service with continuous high differential pressure in the closed position.
• First choice for: Fluids with fine particles, high differential pressure service, frequent cycles where seat hardness is the primary requirement.
• Limitation vs. TFM1600: Slightly lower tightness at very low differential pressure — for pure gas service where absolute tightness is critical, TFM1600 is preferable.

Construction Materials

Technical Specifications

• Type: Double eccentricity wafer high-performance butterfly valve
• Design Standard: API 609
• Actuator Mounting Pad: ISO 5211
• Flange: ANSI B16.5 Class 150
• Body Material: WCB (ASTM A216 Gr. WCB)
• Disc: SS316
• Seat: TFM1600 or RPTFE — specify when ordering
• Sealing: Tight shut-off
• Nominal Pressure: ANSI 150 lb
• Maximum Temperature: ≤180 °C
• Pneumatic Actuator: Single or double acting
• Electric Actuator: ON/OFF or modulating

Fluid Compatibility — WCB + SS316 + TFM1600/RPTFE

• ✅ Natural gas and LPG — the most frequent service for this valve in Mexico
• ✅ Process steam up to 180 °C
• ✅ Crude oil, process oils, and hydrocarbon condensates
• ✅ Dry industrial gases — N₂, CO₂, compressed air, H₂
• ✅ Natural gas with traces of H₂S and wet CO₂ — SS316 disc resists better than SS304
• ✅ Petrochemical process fluids non-corrosive to the WCB body
• ✅ Process water without high chlorides at temperatures up to 180 °C
• ⚠️ Water with high chlorides or acids: WCB body may corrode — use CF8M version
• ⚠️ Fluids with abrasive particles: specify RPTFE seat instead of TFM1600
• ❌ HF, concentrated H₂SO₄, strong acids: use PFA anti-corrosion version

Automation — ISO 5211, Reduced Torque due to Double Eccentricity

Double eccentricity reduces operating torque in the intermediate position compared to conventional butterfly valves — the disc is separated from the seat for almost the entire stroke. Maximum torque is concentrated in the last degrees of closure. In gas service, where the valve operates frequently, this torque reduction accumulates significant energy savings in pneumatic actuators over the valve's lifespan.

• Single-acting NC pneumatic actuator: The standard safety configuration for natural gas and LPG — the mechanical spring ensures closure in case of any control system failure without reliance on active electronic components. See butterfly valves with pneumatic actuator →
• ON/OFF or modulating electric actuator: For installations without a compressed air network or with Modbus integration to SCADA. See butterfly valves with electric actuator →

Main Applications

• Natural gas and LPG — distribution and transportation: The most frequent application of the HP WCB butterfly valve in Mexico. Gas pipeline, compression station, and industrial distribution piping classes often specify WCB + SS316 disc for butterfly valves in gas service. Double eccentricity provides better sealing and longer TFM1600 seat life than conventional butterfly valves with EPDM in this service.
• Petrochemical and refineries — WCB piping class: Refinery and petrochemical plant piping classes define WCB as the body material for butterfly valves in liquid and gaseous hydrocarbon services. The HP WCB version meets these specifications with a TFM1600 seat that resists hydrocarbons without the swelling of EPDM.
• Process steam — up to 180 °C: Isolation of steam lines in industrial plants, boilers, and distribution systems where the temperature exceeds the limit of EPDM (120 °C). TFM1600 maintains its sealing properties up to 180 °C, and WCB withstands standard process steam pressures.
• Oil & Gas — production facilities: Isolation valves in production manifolds, separators, and process equipment where WCB ANSI 150 is the specified rating for hydrocarbon service. Double eccentricity reduces seat maintenance frequency compared to standard butterfly valves in continuous service.
• Power generation — steam and process gases: Isolation in process steam systems, combustion gases, and process fluids in thermal and combined cycle power plants where piping classes specify WCB and the temperature exceeds the limit of conventional elastomers.
• Manufacturing industry — high-temperature plant services: Control of heating steam, thermal oil, and industrial gases in installations where conventional butterfly valves with EPDM fail due to temperature and CF8M is over-specified for the service. The HP WCB covers this specific range.

For corrosive fluids requiring stainless steel body, see HP CF8M SS316 butterfly valve →

TFM1600 Technical Data Sheet

RPTFE Technical Data Sheet