The working principle of gate valves and how to select gate valves

   A gate valve is a shut-off valve that operates by raising or lowering a vertical gate (wedge-shaped or parallel disc) to open or close the fluid passage. It is widely used in industrial piping systems for complete isolation (fully open or fully closed) and is unsuitable for flow regulation.

1.Core Features & Working Principle：

   Key Component – Gate/Disc:

    Typically wedge-shaped (solid, split, or flexible wedge) or parallel (single or double disc).

    The gate moves perpendicularly to the fluid flow direction.

2.Operation:

   Activated by rotating a handwheel, gearbox, or actuator (electric, pneumatic, hydraulic) on the valve stem.

   The stem’s rotary motion converts into the gate’s vertical linear motion via a threaded stem nut.

3.Open state:

   When fully raised, the gate’s passage aligns completely with the valve body, creating a straight, unrestricted flow path with minimal fluid resistance and pressure drop.

4.Closed  state

   When fully lowered, the gate’s sealing surfaces press firmly against the valve seats, forming a metal-to-metal or metal-to-soft-seat (e.g., rubber, PTFE) seal to block fluid flow.

5.Flow Characteristics

   Gate valves are typically full-bore (or near full-bore), meaning the open flow area matches the pipe’s inner diameter, allowing straight-through flow with low turbulence.

6.Key Advantages

   Low Fluid Resistance: Minimal pressure drop when fully open, enhancing energy efficiency.

   Low Operating Torque: Fluid pressure balances gate forces during opening/closing (especially in double-disc designs), reducing effort (vs. globe valves).

   Bidirectional Flow: Symmetrical design allows flow from either direction without affecting sealing or operation.

   Compact Structure (vs. Globe Valves): Shorter face-to-face length saves space.

   Reliable Sealing: Effective sealing in closed state (especially with resilient-seated or metal-seated wedge gates).

   Wide Compatibility: Suitable for water, steam, oil, gas, and corrosive media (with appropriate materials).

7.Key Disadvantages

   Slow Operation: Gate requires full travel to open/close.Sealing Surface Wear: Friction between gate and seats during operation causes erosion, especially with abrasive fluids.

   Difficult Maintenance: Repairing damaged seats/gates often requires specialized tools.

   Large Size/Weight: Bulky design demands significant installation space (height).

   Unsuitable for Throttling: Partially open positions cause high-velocity flow erosion, vibration, and seal damage. Must only be used fully open or fully closed.

   High Cost: Especially for large-diameter, high-pressure applications

8.Major Structural Types

 8.1By Gate Design:

   Wedge Gate Valve: Most common. V-shaped wedge creates sealing force via angle compression or elastic deformation. Reliable sealing, adaptable to thermal changes. Subtypes: Solid wedge, split wedge (self-adjusting), flexible wedge (thermal compensation).

   Parallel Slide Gate Valve: Two parallel discs. Sealing relies on a spreader mechanism (e.g., bottom wedge) or fluid pressure pushing discs against seats. Simpler structure, less prone to jamming, but inferior sealing at low pressure.

 8.2By Stem Movement

   Rising Stem (OS&Y): Stem threads are external. Stem rises during opening, visually indicating position. Resists corrosion but requires vertical clearance.

   Non-Rising Stem (NRS): Stem threads are internal. Stem rotates without lifting, saving vertical space. Ideal for confined areas (e.g., underground) but hides position, and threads are exposed to fluid/corrosion.

9.Typical ApplicationsGate valves are ideal for low-resistance, full-open/full-close isolation in:

    Water Systems: Water treatment plants, sewage networks, building mains.

   Oil & Gas: Pipelines, refineries, transmission lines.

   Power Plants: Boiler feedwater, steam systems.

   Chemical Industry: Corrosive/non-corrosive fluid transport (material-dependent).

   HVAC: Large-system main pipelines.

   SHANDONG EPOCH EQUIPMENT CO., LTD. is a large-scale professional manufacturer in Shandong Province of China, adheres to the orientation of science and technology, environmental protection, quality and efficiency. At present, it has grown into a trans-regional and multi-industrial enterprise integrating such wide industries as design, development, production and export. Visit our website at https://www.epochpipeline.com/ to learn more about our products. For inquiries, you can reach us at sdepochwater@hotmail.com.epochpipeline@hotmail.com