Flange End Wafer Type Butterfly Valve

2 month ago

5 0 

4 year

Product details

1. Definition & Working Principle

A butterfly valve is a quarter-turn rotary valve. Its circular disc rotates 0~90° around the stem: the disc blocks fluid flow when perpendicular to flow direction for full shutoff; it opens fully when parallel to fluid flow; any intermediate angle enables flow throttling, serving both shut-off and flow regulation purposes.

Core components: Valve Body, Disc, Stem and Seat. Available actuators include manual lever, worm gear, pneumatic and electric operators.

2. Main Classifications

2.1 By End Connection

1. Wafer Type: Clamped between two pipeline flanges, compact and cost-effective, commonly DN50~DN1200 for PN10/PN16.

2. Flanged Type: Bolted to piping via integral flanges, higher pressure rating PN16~PN25 / Class150/300 for easy maintenance and disassembly.

3. Lug Type: Body with tapped lug bosses allowing single-side pipe removal, widely used in fire protection and independent double-ended piping.

2.2 By Sealing Design

- Soft-seated Concentric Butterfly Valve: EPDM/NBR rubber seat with zero leakage, low pressure ≤16 bar, suitable for normal-temperature clean water, HVAC circulating water and sewage at -20℃~120℃.

- Double Offset Metal Seated: Double eccentric structure eliminates friction between sealing faces during operation, rated PN25~PN40 for medium-temperature steam, oil and gas service.

- Triple Offset Metal Seated: Multi-layer metallic seat, high temperature resistance up to 550℃ and high pressure Class600/900, bi-directional bubble-tight shutoff for high-temperature flue gas, steam and heavy oil in chemical industry.

2.3 By Operation Mode

Manual Lever, Worm Gear, Pneumatic Actuator, Electric Actuator, Hydraulic Actuator.

3. General Technical Data

1. Size Range: DN40～DN3000 (1.5''~120'')

2. Pressure Class: PN6/PN10/PN16/PN25/PN40 per GB; Class150/300/600 per ASME standard.

3. Material Options

- Body: Cast Iron, Ductile Iron, WCB Carbon Steel, CF8(304), CF8M(316) Stainless Steel

- Disc: QT450 Ductile Iron, 304/316 Stainless Steel, Hard Chrome Plated, Stellite Overlay

- Seat: EPDM, NBR, PTFE, Hard Metal Alloy

4. Applicable Media: Potable water, circulating water, wastewater, oil products, natural gas, steam, flue gas, weak acid & alkaline solutions.

5. Operating Temperature: -20℃~120℃ for soft seat; -40℃~550℃ for all-metal hard seat.

4. Advantages & Disadvantages

Advantages: Compact structure, lightweight, fast 90° on-off action, low flow resistance, cost-efficient for large bore sizes and minimum installation footprint.

Disadvantages: Conventional soft seal cannot withstand extreme high temperature & pressure; standard concentric butterfly valve delivers less precise throttling compared with ball valve.

5. Application Fields

Municipal water supply & drainage, central air-conditioning HVAC, fire service, power plant circulating water, metallurgical flue gas, petrochemical, ship ballast water, wastewater treatment and papermaking pipeline systems.

I. Definition and Structure

Abutterfly valveis a type of rotary valve that controls fluid flow by rotating a circulardisc(orbutterfly plate) around astem. It belongs to the category of quarter-turn valves. Its core components include:

• Valve Body: Cylindrical, housing the disc and providing structural support.

• Disc: Circular thin plate that rotates to regulate flow by changing its angle relative to the fluid direction.

• Stem: Shaft that supports the disc’s weight and transmits torque from the actuator. Typically heat-treated for corrosion resistance.

• Seal Ring: Mounted on the valve body or disc periphery to prevent leakage. Materials include rubber, PTFE, or metal.

II. Working Principle

The butterfly valve operates by rotating the stem, which drives the disc to pivot within the valve body (axis or eccentric axis) through a90° (or less) rotation:

• Fully Open: Disc rotates to90°, parallel to fluid flow, minimizing resistance and maximizing flow.

• Fully Closed: Disc rotates to0°, perpendicular to fluid flow, blocking flow entirely.

• Throttling Mode: At angles between15°–70°, the valve precisely controls flow rate, ideal for sensitive adjustments.

III. Types and Classifications

Butterfly valves are categorized by structure, sealing method, and connection type:

1. By Structural Design

• Concentric (Zero-Offset) Butterfly Valve: Stem, disc, and valve body share a common centerline. Simple design for low-pressure applications.

• Double-Eccentric Butterfly Valve: Stem axis offsets from both disc and valve body centers, reducing seal friction and enabling higher pressure ratings.

• Triple-Eccentric Butterfly Valve: Adds angular offset to double-eccentric design, achieving frictionless sealing for high-temperature/pressure service.

2. By Sealing Method

• Soft-Sealed Butterfly Valve: Uses elastomeric seals (e.g., rubber, PTFE) for excellent leakage control in low-pressure systems.

• Metal-Sealed Butterfly Valve: Employs metal seals for durability under high temperature, pressure, or abrasive conditions.

3. By Connection Type

• Wafer-Type Butterfly Valve: No flanges; bolted between pipeline flanges. Compact and lightweight.

• Lug-Type Butterfly Valve: Features lugs on the valve body for bolt-through connection to pipelines. Suitable for dead-end service.

• Flanged Butterfly Valve: Integral flanges for bolted connection to pipeline flanges. Robust and easy to disassemble.

• Welded Butterfly Valve: Ends are welded directly to pipelines for high-pressure or leak-critical applications.

4. By Actuation Method

• Manual Butterfly Valve: Operated via handles or worm gears for local control.

• Electric Butterfly Valve: Driven by electric actuators for remote or automated operation.

• Pneumatic Butterfly Valve: Uses pneumatic actuators for rapid response in high-speed applications.

• Hydraulic Butterfly Valve: Powered by hydraulic actuators for large-diameter, high-pressure systems.

IV. Performance Characteristics

• Simple Structure: Few components, compact design, and lightweight.

• Rapid Operation: Full open/close in a90° turn, minimizing stroke time.

• Low Flow Resistance: Disc thickness is the sole obstruction when fully open, reducing pressure drop.

• Precise Throttling: Sensitive flow control between15°–70°, ideal for large-diameter regulation.

• Excellent Sealing: Soft or metal seals cater to diverse leakage requirements.

• Easy Installation/Maintenance: Few internal parts and no "pocket" structures simplify upkeep.

V. Applications

Butterfly valves are widely used across industries due to their versatility:

• Oil & Gas: Handling corrosive media, oils, liquid metals, and radioactive fluids.

• Power Generation: Cooling water systems, boiler feedwater lines in thermal power plants.

• Metallurgy: Regulating blast furnace gas, converter gas, and other high-temperature flows.

• Water Treatment & Municipal Engineering: Water distribution networks, wastewater treatment plants, and HVAC systems.

• Ventilation & Dust Control: Bidirectional flow control in ventilation ducts and dust collection systems.

VI. Selection and Installation Guidelines

1. Match Valve Type to Operating Conditions: Consider medium temperature, pressure, and corrosivity when selecting valve design and seal material.

2. Evaluate Flow Control Needs: For precise throttling, choose valves with good regulation performance and proper sizing.

3. Prioritize Corrosion Resistance: Select valve body and seal materials compatible with the medium’s chemical properties.

4. Verify Installation Orientation: Ensure alignment, height, and flow direction comply with design specifications, with secure connections.

5. Pre-Installation Inspection: Check valve nameplate, appearance, and sealing integrity before installation.