Pneumatic High Performance Triple Offset Wafer Butterfly Valve
A pneumatic high performance triple offset wafer butterfly valve
combines non-rubbing triple-offset geometry, a multilayer metal sealing
system and pneumatic quarter-turn operation. It is designed for automated
shutoff in high-temperature, high-pressure and high-cycle industrial
pipelines where conventional soft-seated butterfly valves may not be suitable.
How Does a Triple Offset Butterfly Valve Work?
The first offset places the shaft behind the disc sealing plane. The
second moves the shaft away from the pipe centerline. The third introduces
an angled, cone-shaped sealing geometry. These three offsets allow the disc
and seat to separate quickly when the valve opens and make sealing contact
mainly near the final closing position.
Because the sealing surfaces do not slide against each other through the
full stroke, friction and wear are reduced. This makes the design suitable
for frequent operation and demanding metal-seated service.
Why Use Pneumatic Actuation?
A pneumatic actuator provides fast 90-degree operation and can be
integrated into an automated process. Depending on the project, the
package may include a solenoid valve, limit switch box, positioner and
air filter regulator. Double-acting and spring-return arrangements can
be selected according to the required fail position.
Final actuator sizing must consider valve torque, differential pressure,
operating frequency, air pressure, cycle time, installation position and
the required safety factor. The actuator should not be selected from
nominal pipe size alone.
WDL Valve Technical Range
| Product Type | Pneumatic high performance triple offset wafer butterfly valve |
|---|---|
| Size Range | DN50–DN400 / NPS 2–16 |
| Flange Compatibility | HG 20592 PN10–PN25, ASME B16.5 Class 150 and JIS 10K |
| Face-to-Face Reference | GB/T 12221 and API 609 |
| Sealing System | Triple-offset multilayer metal sealing system |
| Actuator Mounting | ISO 5211 |
| Operation Options | Pneumatic actuator; manual, worm gear and electric options available |
Dimensions, pressure ratings and torque figures are reference information.
The final construction must follow the approved WDL Valve drawing and
project datasheet.
Main Design Features
- Triple-offset geometry reduces sliding contact between disc and seat.
- Multilayer metal sealing supports demanding temperature and pressure conditions.
- Wafer body provides compact installation between compatible pipeline flanges.
- Pneumatic actuator supports rapid on/off control and process automation.
- ISO 5211 mounting platform simplifies actuator connection.
- One-piece precision-cast body construction.
- Self-lubricating bearings help reduce operating torque.
- Graphite packing is available for high-temperature stem sealing.
Available Material Options
Material selection should be based on the medium, temperature, pressure,
corrosion risk, solids content and project specification. WDL Valve can
configure the main components in carbon steel, stainless steel, duplex,
super duplex, titanium and nickel alloys.
| Component | Available Materials |
|---|---|
| Valve Body | WCB, WCC, CF8, CF8M, CF3, CF3M, 4A, 5A, Titanium Grade 2 and nickel alloy |
| Disc | CF8, CF8M, CF3, CF3M, 4A, 5A, Titanium Grade 2 and nickel alloy |
| Stem | 17-4PH, 304, 304L, 316, 316L, 2205, 2507, Titanium Grade 2, nickel alloy or Monel |
| Seat | 304, 304L, 316, 316L, 2205, 2507, Titanium Grade 2 or nickel alloy; polymer options are available for compatible duties |
| Packing and Gasket | PTFE, RPTFE, TFM or graphite according to service conditions |
Triple Offset Metal Seat vs. Soft Seat
| Selection Factor | Triple Offset Metal Seat | Soft Seat |
|---|---|---|
| Sealing movement | Cam-like, low-rubbing contact near final closure | Disc compresses or wipes across an elastomer or polymer seat |
| Typical conditions | Elevated temperature, pressure, high cycling or demanding media | General water, air and compatible utility service |
| Seat material | Metal or multilayer metal construction | Elastomer or polymer |
| Selection priority | Durability under severe operating conditions | Low torque and tight shutoff within seat limits |
Typical Applications
- Power generation, steam and hot utility systems
- Oil, gas, refinery and petrochemical processing
- Coal chemical production and industrial gas lines
- Vacuum and high-cycle pipeline service
- Metallurgy and industrial furnace systems
- Pulp and paper, textile dyeing and light industry
Information Required for Correct Valve Selection
- Process medium, composition and solids content.
- Normal and maximum operating temperature.
- Operating pressure, design pressure and maximum differential pressure.
- Valve size, flange standard, pressure class and face-to-face requirement.
- Required shutoff direction and leakage acceptance criteria.
- Cycle frequency, required opening time and emergency shutdown duty.
- Air supply pressure, fail-open or fail-closed position and accessory requirements.
- Material, corrosion allowance, fire-safe or other project requirements.
ISO 5211
defines attachment requirements for part-turn valve actuators, while
API 609
covers butterfly-valve construction, including wafer designs. The
purchase specification should state the required standard edition and
project-specific additions.
Frequently Asked Questions
What is the third offset in a triple offset butterfly valve?
The third offset is the angular relationship of the conical sealing
surfaces. It helps remove sliding contact between the seat and disc
through most of the operating stroke.
Can this valve be used for steam?
It can be configured for compatible steam service. WDL Valve must verify
the pressure, temperature, material, packing, sealing design and actuator
torque for the actual operating point.
Is the valve suitable for throttling?
Triple offset butterfly valves can be considered for certain regulating
duties, but sizing must evaluate flow velocity, pressure drop, cavitation,
vibration and actuator control. A control application should not be
selected from pipe size alone.
What pneumatic accessories are available?
A typical package may include a solenoid valve, limit switch box,
positioner and air filter regulator. The exact accessories, enclosure
protection and hazardous-area certification must be stated in the enquiry.
How should the actuator be sized?
Actuator sizing should use the valve torque at the specified differential
pressure, air-supply pressure, cycle time and a suitable safety factor.
WDL Valve confirms the final selection from the project operating data.
Discuss Your Triple Offset Butterfly Valve Application
Send WDL Valve your medium, size, pressure, temperature, flange standard,
air supply and fail-position requirements for technical review.
Related Triple-Offset Butterfly Valves
For flanged pipeline connections, see the Pneumatic Flanged Triple-Offset Butterfly Valve. For a metal-seated pneumatic design, review the D673H Pneumatic Triple-Eccentric Butterfly Valve.
