The sliding gate valve realizes the opening and closing control of the fluid passage through the linear sliding of the gate. Its core operating mechanism relies on the sealing cooperation between the gate and the valve body and the transmission mechanism design. It is widely used in industrial pipeline systems that require full open/full close control.
1. Working principle and operation process
Gate sliding mechanism
Opening and closing action: The operating mechanism (handwheel, gear set or electric device) drives the valve stem to rotate, and the rotational motion is converted into the vertical lifting of the gate through the threaded transmission;
Fluid control:
Open state: The gate is fully lifted to the top of the valve cavity, the fluid passage is fully opened, and the flow resistance is close to zero;
Closed state: The gate is pressed down to the valve seat sealing surface to block the flow of the medium. The sealing interface can rely on the medium pressure to self-seal or external pressure to force sealing.
Transmission system adaptation
Manual operation: Small-diameter valves with a DN of ≤300 are mostly directly driven by handwheels, with a torque of ≤150N·m; Gear assistance: Large-diameter (DN≥400) or high-pressure (PN≥40) working conditions are equipped with bevel gear reduction devices to reduce the operating torque to 1/5-1/3 of the original value.
2. Structural features and sealing design
Core components
Gate type: Wedge-shaped single gate: Suitable for clean media, wedge angle 5°-10°, sealing is achieved by forced compression; Parallel double gate: Contains spring compensation structure, suitable for media containing particles or temperature fluctuations, and the self-adjustment deviation of the sealing surface is ≤0.1mm. Valve seat treatment: The sealing surface is welded with cobalt-based alloy (such as Stellite 6), with a hardness of ≥HRC55 and a wear-resistant life of 100,000 openings and closings.
Seal Enhancement Technology
Self-sealing mode: When closed, the medium pressure pushes the gate to press the valve seat, which is suitable for medium and low pressure (≤PN25) working conditions;
Forced sealing mode: Apply additional axial force through the valve stem to ensure zero leakage under high pressure (PN≥64) or vacuum conditions (leakage level API 598 VI).
3. Typical application scenarios
Water treatment system: Flow blocking of municipal trunk pipelines (DN≥1200), resistant to sediment scouring; Chemical plant: Isolation control of corrosive medium pipelines (pH2-12), nitriding treatment of valve stems to enhance corrosion resistance; Energy field: Emergency shut-off of high-temperature steam pipelines (≤570℃), alloy sealing surface resistance to thermal deformation.
The sliding gate valve achieves high-reliability fluid cut-off function under harsh working conditions through structural optimization and material adaptation. Its design logic is technically homologous to gear gate valves and manual gate valves.
