Pneumatic Triple-Offset Metal-Seated Butterfly Valve

D643W-150LLB Pneumatic Triple-Offset Metal-Seated Butterfly Valve – Product Manual
I. Product Overview
The D643W-10 is a flanged, triple-offset, metal-seated pneumatic butterfly valve with a nominal pressure of PN10. It features a triple-offset design, with the “W” designation indicating a stainless steel metal-to-metal seal. Powered by compressed air, the pneumatic actuator drives the butterfly disc to rotate between 0° and 90°, enabling pipeline media shut-off and flow regulation. It can be equipped with solenoid valves, limit switches, and valve positioners for integration into DCS automation control systems, and explosion-proof options are available.
The triple-offset structure allows the disc to disengage from the seat immediately upon opening, eliminating friction and wear. This ensures high-temperature resistance, wear resistance, and stable sealing performance, making it ideal for pipelines transporting high-temperature flue gas, steam, fuel gas, oil products, and mildly corrosive industrial fluids.
II. Model Designation
D: Butterfly Valve
6: Pneumatic Actuation
4: Flange Connection
3: Triple-Offset Structure
W: Stainless Steel Metal-to-Metal Seal
10: Nominal Pressure PN10 (1.0 MPa)
III. Structural Features

1. Triple-Offset Frictionless Sealing: The 3D offset structure ensures the sealing surfaces disengage the moment the disc opens, eliminating friction during operation. This significantly extends service life and ensures stable sealing performance under high-temperature conditions.
2. High-Temperature Resistant Metal Seal: Features an all-metal sealing pair capable of withstanding high-temperature media. It offers resistance to erosion and wear, making it suitable for media containing trace amounts of dust.
3. Reliable Flanged Connection: The flanged structure ensures stable installation and pressure integrity; compatible with HG20592 national standard flanges.
4. Flexible Pneumatic Actuation: Supports double-acting (continuous air supply) and single-acting spring-return (automatic close/open upon air loss for safety interlocking) configurations; can be fitted with a positioner for proportional control. 5. Blow-out-proof Stem Design: The stem features a blow-out-proof design with flexible graphite packing, ensuring a low risk of external leakage at high temperatures.
5. Easy Maintenance: Modular structure allows for the replacement of sealing components without removing the entire valve from the pipeline.
   IV. Technical Parameters

• Model: D643W-10
• Nominal Pressure: PN10 (1.0 MPa)
• Nominal Diameter: DN50–DN1200
• Connection Type: Flanged (HG20592)
• Structure: Triple-offset
• Sealing Type: Metal-to-metal hard seal (W: stainless steel sealing pair)
• Actuation: Pneumatic actuator (AT/GT type; single-acting or double-acting options available)
• Air Supply Pressure: 0.4–0.8 MPa
• Operating Temperature: -20°C to 425°C
• Applicable Media: Steam, air, flue gas, fuel gas, oil products, water, seawater, mildly corrosive gases/liquids
• Leakage Class: GB/T13927 Class VI
• Flow Characteristic: Approximate equal percentage; suitable for on/off isolation or flow regulation
• Valve Body Material: Stainless steel (W)
• Butterfly Disc: Stainless steel
• Stem: 2Cr13 / 304 stainless steel
• Packing: Flexible graphite
  V. Applicable Operating Conditions
  ✅ Recommended Applications

1. Thermal & Boiler Systems: High-temperature steam, flue gas, hot air ducts;
2. Gas & Coal Chemical Industries: Shut-off for fuel gas, natural gas, and industrial gases;
3. Petroleum & Heating: Thermal oil and various oil product pipelines;
4. Power Plants & Metallurgy: Flue gas with low dust content, circulating water;
5. Automated Processes: Remote pneumatic on/off control, interlocked emergency pipeline shut-off. ❌ Inapplicable Operating Conditions
6. Highly corrosive media (strong acids/alkalis); for highly corrosive applications, please select fluorine-lined valves;
7. Media containing large quantities of hard, coarse particles or causing severe erosion;
8. Operating conditions exceeding rated temperature or pressure parameters.
   VI. Applicable Standards

• Design & Manufacture: GB/T12238
• Face-to-Face Dimensions: GB/T12221
• Flange Standard: HG20592
• Pressure Testing: GB/T13927, API598
• Explosion-proof: Ex d IIC T6 (Explosion-proof version available)
  VII. Installation and Operation Instructions

1. Clean welding slag and debris from the pipeline before installation to prevent hard particles from scratching the metal sealing surfaces;
2. The valve can be installed horizontally or vertically; ensure sufficient clearance for actuator maintenance;
3. Install an air service unit (filter, regulator, and lubricator) upstream of the air supply to ensure the compressed air is clean and dry;
4. Manually operate the valve before initial commissioning to ensure the disc moves freely without binding, then connect the air supply to calibrate the zero point and full stroke;
5. For high-temperature applications, a gradual temperature rise is recommended to avoid thermal shock;
6. Regularly inspect the air supply and fasteners; for prolonged periods of inactivity, periodic full-stroke cycling is recommended to prevent the sealing surfaces from sticking;
7. Single-acting spring-return models provide fail-safe protection upon air supply loss, meeting process safety interlock requirements.
   VIII. Product Advantages Summary
   The D643W-10 triple-offset pneumatic metal-seated butterfly valve utilizes a friction-free triple-offset metal seal, offering high-temperature and wear resistance alongside reliable sealing performance. It features rapid response for remote pneumatic operation and a PN10 pressure rating, making it an ideal choice for automated shut-off and regulation in pipelines carrying steam, flue gas, fuel gas, or high-temperature oils.