4A National Standard Flange Butterfly Valve is a high-performance flow control device utilizing CD3MN (4A Duplex Stainless Steel) to handle corrosive and abrasive media. Engineered with an advanced Triple Eccentric (Three-Dimensional) Metal Seal structure, this valve is designed for high-pressure and high-temperature service up to 550°C in metallurgy, petrochemical, and industrial drainage systems.
Description
Unlike standard butterfly valves, this model incorporates a third eccentric angle (B), which creates a conical sealing profile.
- Frictionless Operation: The three-dimensional structure ensures that the valve seat and butterfly plate remain separate until the final moment of closure. This eliminates friction during the entire 90° travel, significantly extending the service life.
- Self-Tightening Function: The “more closed, more tight” mechanism uses the torque applied during closing to increase sealing pressure, ensuring a bubble-tight shut-off even under high-pressure conditions.
- Torque Adjustment: The unique slope of the cone allows operators to adjust the seal overpressure arbitrarily via torque changes, making the seal more reliable and preventing leakage phenomena.
Features
- Advanced Material (4A Duplex): Built from CD3MN (4A) duplex stainless steel, providing superior mechanical strength and elite resistance to pitting and stress corrosion cracking (SCC) compared to standard 316L.
- Dual Sealing Advantage: The butterfly plate utilizes a multi-layered composite seal (hard metal layers interleaved with flexible soft layers). This provides the durability of a metal-to-metal seal with the zero-leakage performance of a resilient seal.
- Hardened Sealing Surfaces: The valve seat is surfaced with cobalt-based alloy (Stellite) welding, offering extreme wear resistance and maintaining integrity under high-velocity flow.
- High-Pressure Stability: The structural design ensures that medium pressure has minimal influence on the operational torque, allowing for nimble and effort-reducing manual or automated operation.
Specifications
| Specification | Standard Reference |
| Design Standard | GB/T 12238 / JB/T 8527 |
| Flange Dimensions | GB/T 9113 / HG/T 20592 |
| Face-to-Face Length | GB/T 12221 |
| Body Material | 4A Duplex Steel (CD3MN / 022Cr22Ni5Mo3N) |
| Pressure Rating | PN10, PN16, PN25, PN40 |
| Testing Standard | GB/T 13927 / JB/T 9092 |
Applications
- Petrochemical & Refining: Handling corrosive hydrocarbons and high-temperature vapors.
- Metallurgy: High-heat gas systems and cooling water circulation in smelting plants.
- Power Generation: Steam extraction and circulating water systems.
- Marine & Desalination: High-chloride seawater environments where duplex strength is required.
