1. Core Structure and Operating Principle
Metal Seal Assembly
Valve Seat Material: Overlay-welded carbide (such as 1Cr13, Stellite cobalt-based alloy) or solid stainless steel forging, resistant to high-temperature wear.
Gate Compatibility:
Rigid Gate: Integrally cast, suitable for high-pressure, stable operation (PN ≥ 16 MPa).
Elastic Gate: A central groove design adapts to slight seat deformation, enhancing sealing reliability.
Sealing Mechanism
Forced Seal: Mechanical force from the valve stem pushes the gate against the valve seat, forming a metal-to-metal contact seal.
High-Pressure Self-Enhancement: Medium pressure assists in compressing the sealing surface, resulting in a tighter seal at higher pressures (up to 42 MPa).
2. Performance Advantages
| Features | illustrate |
|---|---|
| High temperature resistance | Applicable to -29℃~550℃ (steam/high temperature oil and gas) |
| Erosion resistance | Carbide sealing surface resists erosion by particle-containing media (such as coal ash, slurry) |
| Long life design | Sealing surface can be repaired after wear (surfacing welding or replacement of valve seat ring) |
| Zero leakage rating | Complies with ANSI Class VI standards (high pressure conditions) |
3. Typical Application Scenarios
Energy Industry
Ultra-high-pressure shutoff of power plant main steam lines (PN420 grade);
Pig transmitter and receiver for long-distance oil and gas pipelines.
Harsh Operating Conditions
Metallurgical blast furnace pulverized coal injection system (resistant to 800°C);
Chemical industry with highly corrosive media (such as concentrated sulfuric acid, using a 316L valve seat).
4. Selection and Maintenance Key Points
Key Parameters
Sealing Surface Angle: Wedge-type gates typically have an inclination angle of 2°52′ to 5°, with a larger angle for low pressures.
Valve Body Material: WCB cast steel for high temperatures; duplex stainless steel for corrosive environments.
Operating Limitations
Suitable only for fully open/fully closed operation. Half-open operation can cause erosion damage to the sealing surface.
The valve stem must be installed vertically; a deflection greater than 3° may cause unilateral wear.