Wafer Butterfly Valve: China ventil ljevaonice

Uvod

A wafer butterfly valve is a critical component in modern industrial fluid systems, providing reliable and efficient flow control across a wide range of applications.

Butterfly valves in general are favored for their lightweight construction, compactness, i isplativost.

The wafer-style design, posebno, is widely used due to its ability to fit snugly between flanges without the need for additional bolting, reducing installation time and material requirements.

With applications spanning HVAC sustavi, obrada vode, kemijska obrada, i ulje & gas pipelines, wafer butterfly valves play a vital role in maintaining precise flow control, sigurnost, and operational efficiency.

1. What is a Wafer Butterfly Valve

A reza butterfly valve is a type of quarter-turn valve used to regulate or isolate fluid flow in pipelines.

The core components include:

• Tijelo: The main casing, designed to fit snugly between two flanges.
  Unlike flanged or lug-style butterfly valves, wafer valves do not require through-bolts; they rely on the compression between flanges for secure installation.
• Disk: The central rotating element that modulates flow. Ovisno o primjeni, the disc may be solid, odzračen, or profiled to optimize flow characteristics.
• Shaft/Stem: Connects the disc to the actuator or manual control, transmitting torque to rotate the disc.
• Seat/Seal: Ensures leak-tight operation when the valve is closed. Seat materials vary depending on temperature, pritisak, and the chemical properties of the medium.

Operating Principle:

The valve operates by rotating the disc 90 degrees (quarter-turn). When the disc is parallel to the flow, the valve is fully open, allowing minimal resistance.

Rotating the disc perpendicular to the flow achieves full closure, effectively stopping the fluid.

Partial rotation enables throttling, although wafer butterfly valves are better suited for on/off or moderate flow control rather than precise metering.

Key Differentiators from Other Butterfly Valves:

2. Design Variations: Concentric vs. Eccentric Wafer Butterfly Valves

Wafer butterfly valves are designed in several configurations to accommodate different flow conditions, pressures, and media types.

The two most common design variations are concentric (also called “resilient-seated”) i eccentric (double or triple offset) wafer butterfly valves.

Concentric (Resilient-Seated) Wafer Butterfly Valves

Structure & Principle:

• The disc is centered on the shaft, which passes through the middle of the disc and valve body.
• The disc rotates within a resilient elastomeric seat (Npr., EPDM, NBR, PTFE) that provides the sealing surface.
• Sealing occurs primarily through elastic deformation of the seat as the disc rotates to the closed position.

  

Prednosti:

• Tight shut-off: Achieves zapečaćenje s mjehurićima (Klasa VI) in many applications.
• Isplativ: Simple design and fewer metallic components reduce manufacturing costs.
• Nisko održavanje: Seat replacement is straightforward, and the design tolerates moderate pressure fluctuations.

Ograničenja:

• Temperature and pressure constraints: Elastomeric seats typically limit use to temperatures below ~200°C (392° F) and pressures below ANSI Class 150-300 ranges.
• Not ideal for abrasive or corrosive fluids: Elastomer seats may wear quickly with slurry, sand-laden liquids, or highly aggressive chemicals.

Prijava:

• Water distribution and treatment
• HVAC sustavi
• Low-pressure chemical or food-grade pipelines

Eccentric (Double & Triple Offset) Wafer Butterfly Valves

Eccentric valves are engineered for higher performance and harsher service conditions. The design offsets the disc from the shaft and/or the sealing surface, which reduces friction and improves sealing over time.

Double Offset (High-Performance Butterfly Valve – HPBV):

• The shaft is offset from the centerline of the disc and seat, creating a cam effect during closing.
• Metal-to-metal or soft-seated options are possible.
• Reduces friction and wear on the seat, extending valve life.

Triple Offset (Metal-Seated Butterfly Valve – TOV):

• Adds an additional offset: the cone-shaped seat axis is offset from the bore and shaft centerlines.
• Provides zero-contact sealing until final closure, minimizing seat wear.
• Prikladno za visokog pritiska, visokotemperatura, or corrosive applications.

Prednosti:

• Handles higher pressures and temperatures, often up to 400°C (752° F) and ANSI Class 600+.
• Durable against abrasive and corrosive media with proper material selection (nehrđajući čelik, duplex legure, or coated discs).
• Can achieve čvrsto isključivanje (Class VI or higher) in demanding applications.

Ograničenja:

• Higher initial cost compared to concentric valves.
• Requires more precise installation and alignment.

Prijava:

• Ulje & gas pipelines
• Steam and high-temperature services
• Chemical and petrochemical industries
• Stvaranje energije

Summary Comparison:

The choice between concentric and eccentric designs depends on operating pressure, temperatura, srednji, and desired cycle life.

Concentric valves dominate in low-pressure water and HVAC applications, while eccentric designs excel in industrijski, kemijski, and high-temperature pipelines.

3. Materials of Wafer Butterfly Valves

The performance, izdržljivost, and suitability of wafer butterfly valves largely depend on the materials used for their tijelo, disk, shaft, and seat.

Proper material selection ensures compatibility with the process media, operating temperature, pritisak, i okolišnim uvjetima.

Body Materials

The valve body serves as the primary structural component and the interface with the piping system.

Material selection is critical to ensure mehanička čvrstoća, otpor korozije, and compatibility with operating pressure and temperature.

Disc Materials

The disc is the moving element controlling flow and provides sealing engagement in resilient or metal-seated valves. Typical materials:

• Nehrđajući čelik (304/316/316L): Corrosion resistance and moderate strength for general-purpose applications.
• Aluminum Bronze: Visok strength and corrosion resistance, often used in seawater and chemical applications.
• Coated Alloys (PTFE, Nikla, or Epoxy): Provide abrasion and chemical resistance, extending service life in aggressive environments.
• Carbon Steel or Ductile Iron: Suitable for low-cost, low-corrosion water applications, sometimes rubber-lined for sealing.

Shaft Materials

The shaft transmits torque from the actuator to the disc and must resist torsional stress, korozija, I nositi:

• Nehrđajući čelik (SS304, SS316): Common in most industrial and water applications.
• Alloy Steel or Duplex Stainless Steel: Visoka snaga, used in high-pressure or corrosive services.
• Surface coatings (hard chrome, Nitronic 60) reduce galling and friction, especially in triple-offset designs.

Sjedalo & Sealing Materials

Seat selection is critical for čvrsto isključivanje, chemical compatibility, and temperature resistance:

4. Design Features of Wafer Butterfly Valves

Wafer butterfly valves are widely appreciated for their compactness, svestranost, and ease of integration into piping systems.

Their design features are engineered to optimize flow control, sealing reliability, and operational efficiency.

Wafer-Style Body Design

• Compact and Lightweight: Wafer valves are sandwiched between two flanges, reducing the need for extra bolt holes or lugged extensions.
  This makes them lighter and easier to install than lug or flanged butterfly valves.
• Flange Compatibility: Designed to fit between standard ANSI, IZ, or ISO flanges, davati broad applicability in industrial pipelines.
• Reduced Footprint: Ideal for tight spaces where other valve types might require more room.

Shaft and Bearing Options

• Single vs. Double Shaft: Single-shaft valves offer simplicity, while double-shaft designs enhance disc stability and minimize wobble under high flow conditions.
• Ležajevi & Čahure: Materials such as PTFE, bronza, or stainless steel bushings reduce friction, improve torque response, and extend cycle life.
• High-Torque Handling: Optimized shaft design ensures reliable operation even in larger diameters (do 1200 mm or more) and higher pressure systems.

Disc and Seat Configurations

• Disc Profiles: Concentric (standard) discs are versatile, while eccentric or double-eccentric discs reduce friction and wear on the seat.
  Some designs include a coated disc (PTFE, epoksidan, or nickel) for enhanced chemical resistance.
• Seat Materials: EPDM, NBR, Viton, or PTFE are selected based on temperatura, chemical compatibility, and sealing requirements.
  Metal-to-metal seats are sometimes used in high-temperature or steam applications.
• Replaceable Seats: Many wafer butterfly valves feature replaceable seat rings, simplifying maintenance and prolonging service life.

5. Actuation Options of Wafer Butterfly Valves

Wafer butterfly valves can be operated manually or automatically, with a variety of actuation methods tailored to different flow control requirements, safety considerations, and industrial environments.

Manual Actuation

• Lever Operated: Common for small- to medium-diameter valves (do 300 mm). Provides quick on/off control with direct visual indication of disc position.
• Gear-Operated (Worm Gear): Suitable for larger valves (nad 300 mm) or high-torque applications. Reduces operator effort by up to 90%, allowing precise throttling.
• Safety Features: Manual actuators may include locking devices to prevent accidental operation in hazardous systems.

Pneumatic Actuation

• Spring-Return vs. Double-Acting:

• • Spring-return: Automatically closes or opens the valve when air pressure is lost—ideal for fail-safe applications.
  • Double-acting: Uses air pressure for both open and close cycles, davati faster response and precise positioning.

• Torque Capability: Pneumatic actuators can generate torques exceeding 5000 Nm, allowing operation of valves in large pipelines (>1000 mm) or high-pressure systems.
• Control Integration: Easily integrated with modulating control systems (0–10 V or 4–20 mA signals) za automatic flow regulation.

Electric Actuation

• Motor-Driven Gearboxes: Suitable for remote operation, precizno ulijevanje, i automated process control.
• Modulating or On/Off Control: Can provide continuous control, allowing variable positioning from 0° to 90° with high accuracy (±1° typical).
• Power Considerations: Electric actuators require correct sizing based on valve torque, pressure differential, and cycle frequency to avoid motor overloading.

6. Performance Parameters of Wafer Butterfly Valve

Wafer butterfly valves are evaluated based on several performance parameters that determine their suitability for specific industrijska primjena.

These parameters include ocjene tlaka, temperature limits, flow characteristics, leakage performance, and operational torque.

Understanding these factors ensures efficient flow control, sigurnost, i dugoročna pouzdanost.

Pressure Ratings

• ANSI/ASME Classes: Most wafer butterfly valves are rated according to ANSI Class 150, 300, ili 600, corresponding to maximum working pressures from 19 bar (275 psi) do 148 bar (2150 psi) at ambient temperature.
• High-Pressure Applications: Specially designed stainless steel or carbon steel valves can handle pressures above 100 bar (1450 psi) u industrial pipelines ili steam systems.
• Pressure vs Temperature: Valve ratings typically decrease at elevated temperatures. Na primjer, razred 150 ductile iron wafer valve rated for 19 bar at 20°C may drop to 15 bar at 121°C.

Temperature Limits

• Seat Material Dependent:

• • EPDM: -40°C to 120°C
  • NBR: -30°C to 100°C
  • PTFE: -196°C to 260°C
  • Viton/FKM: -20°C to 200°C

• Body Material Consideration: Stainless steel and carbon steel can operate up to 400–482°C, whereas cast iron is limited to 121° C.

Koeficijent protoka (Životopis)

• A Cv value indicates the flow capacity of a valve: the volume of water (in US gallons per minute) that passes through the valve with a 1 psi pressure drop.
• Typical wafer butterfly valves have Cv values ranging from 25 do 5000, ovisno o diameter (DN 50–1200 mm) and disc design.
• High Cv design ensures minimal pressure drop and energy-efficient pumping, posebno u HVAC and water distribution systems.

Klasa curenja

• Butterfly valves are tested according to Apikat 598, ISO 5208, or BS 5155 standardima.
• Common leakage classes:

• • Class II: Low-pressure non-critical applications
  • Class IV: Moderate tightness for water, zrak, and low-viscosity fluids
  • Klasa VI: High-precision sealing for pari, plin, or chemical service, postizanje bubble-tight shutoff (<0.01% of rated flow)

Torque Requirements

• Torque varies based on valve size, pressure differential, seat material, and actuator type.
• Primjer: A Dn 300 EPDM-seated wafer valve may require 150–250 Nm to operate under 10 bar pressure, dok a Dn 600 PTFE-seated valve may need 450–600 Nm.
• Proper sizing prevents actuator overload, reduces wear on seats and shafts, and ensures reliable cycling.

Durability and Cycle Life

• Industrial wafer butterfly valves are designed for 50,000 do 500,000 ciklusi ovisno o actuation method and media.
• Heavy-duty stainless steel valves in water or air applications can exceed 1 million cycles with minimal maintenance.
• Wear-prone components: Seats and shafts are inspected regularly, Pogotovo u abrasive or corrosive media.

7. Applications of Wafer Butterfly Valves

• HVAC sustavi: Air and water flow control in large buildings
• Water treatment: Raw water, otpadne vode, and chemical dosing pipelines
• Kemijska obrada: Corrosive liquids and gases
• Ulje & plin: Fuel pipelines, komprimirani zrak, and venting systems
• Hrana & piće, farmaceutski proizvodi: Hygienic valves with EPDM/PTFE seats for cleaning-in-place (Proći) sustava
• Pare, plin, and slurry: Triple-offset designs withstand abrasive and high-temperature media

8. Advantages and Limitations

Prednosti of Wafer Butterfly Valve

• Kompaktan i lagan, reducing installation cost by 15–25% compared to flanged valves
• Low-pressure drop (~2–5% at full open)
• Quick quarter-turn operation
• Minimal maintenance requirements
• Flexible material options for corrosive and high-temperature environments

Ograničenja of Wafer Butterfly Valve

• Not ideal for ultra-high-pressure or highly abrasive media
• Seat wear can occur with frequent throttling or slurry handling
• Torque may increase in large-diameter valves, requiring actuators

9. Comparison to Other Valve Types

Wafer butterfly valves are widely used in industry due to their Kompaktni dizajn, isplativost, and moderate performance,

but it is important to compare them with other common valve types to understand suitability, ograničenja, and performance differences.

10. Standards and Compliance

Wafer butterfly valves must adhere to global standards to ensure safety, interoperability, and performance:

• Apikat 609: Governs design, materijal, testiranje, and marking of butterfly valves (mandatory for oil and gas).
• ISO 10631: International standard for butterfly valves (aligns with API 609).
• ASME B16.34: Specifies pressure-temperature ratings for metallic valves.
• ANSI/ISA-75.01: For control valve sizing and flow characteristics (throttling applications).
• 3-A Sanitary Standards: For food, dairy, and pharmaceutical valves (hygienic design).

Compliance with these standards ensures the valve meets industry-specific requirements (Npr., low emissions for oil and gas, hygiene for food).

11. Future Trends in Wafer Butterfly Valve Technology

Innovation in wafer butterfly valves is driven by sustainability, automation, and extreme environment needs:

• Smart Valves: Integration of sensors (pritisak, temperatura, položaj) and IoT connectivity to monitor performance in real time.
  Na primjer, wireless sensors detect seat leakage and transmit data to plant SCADA systems, enabling predictive maintenance.
• Low-Emission Designs: Improved stem sealing (Npr., double packing with graphite) to meet ISO 15848-1 Class AH (≤1×10⁻⁹ Pa·m³/s fugitive emissions)—critical for oil and gas and chemical industries.
• Advanced Materials: Use of ceramic-coated discs (for abrasion resistance) and thermoplastic composites (for lightweight, corrosion-resistant bodies) to extend service life in harsh environments.
• Aditivna proizvodnja: 3D-printed valve components (Npr., eccentric discs, seat inserts) to create complex geometries that improve sealing and reduce weight.

12. Zaključak

Wafer butterfly valves have earned their place as a versatile, cost-effective fluid control solution, balancing compact design, quick operation, and broad material compatibility.

Their ability to handle large diameters, bidirectional flow, and diverse fluids makes them indispensable in water treatment, HVAC, kemijska obrada, te nafte i plina.

By understanding design variations (concentric vs. eccentric), odabir materijala, and performance metrics, engineers can select the right valve for their application—ensuring efficiency, sigurnost, and long service life.

Česta pitanja

Can wafer butterfly valves be installed vertically?

Da, but ensure the actuator is mounted above the valve to prevent fluid from entering the actuator. For large valves (>12 inča), use a support bracket to reduce flange stress.

Can wafer butterfly valves handle gas service?

Da, but only double/triple eccentric designs with Class VI leakage (PTFE or metal seats).

Ensure the valve is tested to ISO 15848-1 Class AH for low emissions (critical for natural gas or toxic gases).

What is the maximum pipe size for a wafer butterfly valve?

Most manufacturers offer wafer butterfly valves up to 48 inča (1200 mm) in diameter, suitable for large water treatment or oil and gas pipelines.

How do I fix seat leakage in a wafer butterfly valve?

Prvi, clean the valve to remove debris. If leakage persists, replace the seat (ensure compatibility with media/temperature). For metal-seated valves, resurface the disc/seat via grinding.

Are wafer butterfly valves suitable for steam service?

Yes—use metal-seated triple eccentric valves (ANSI Class 300–600) with carbon steel or 316L bodies. Avoid soft seats (EPDM/PTFE), which degrade above 260°C.

What is the difference between ANSI Class 150 i 300 wafer valves?

ANSI Class 150 valves handle up to 28 bar (20° C), dok je Klasa 300 handles up to 70 bar (20° C).

Class 300 valves have thicker bodies and stronger stems, making them suitable for higher-pressure applications (Npr., kemijski reaktori).