Pipeline gate valve Description
Pipeline gate valve is a key valve installed in the pipeline system to control the flow of the medium. Its core function is to achieve full opening or shutoff of the pipeline rather than regulating the flow.
Working principle: When the gate is fully raised, the valve is in the fully open state, and the fluid can pass freely; when the gate is lowered to the lowest position, the valve is in the fully closed state, blocking the flow of fluid. Gate valves are generally not suitable for regulating flow because they are designed to provide two states: fully open or fully closed.
Design features
- Structural form
Gate type : divided into wedge type (single gate, elastic gate, double gate) and parallel gate type, opening and closing are achieved by vertical lifting of the gate.
Valve stem design :
Open stem structure : The valve stem can be seen when it is lifted and lowered, which is suitable for scenes with sufficient space and is convenient for observing the valve status.
Concealed stem structure : The valve stem only rotates without lifting and lowering, which saves installation height, but the opening cannot be judged intuitively.
Flow channel type :
Full bore type : The flow channel aperture is equal to the nominal diameter, and the flow resistance is extremely small, which is suitable for pipelines with high requirements for conveying efficiency.
Reduced bore type : The flow channel aperture is smaller than the nominal diameter, which can reduce the opening and closing torque, but will increase the flow resistance and energy consumption.
- Sealing and driving mechanism
The sealing surface achieves high flatness through precision machining, and relies on medium pressure or external force to force the valve seat to close when closed.
The valve stem converts the rotational force into linear motion to drive the gate through trapezoidal threads, which saves effort in operation
gate valve in pipeline specification
1. Gray cast iron gate valve
Nominal diameter (DN):
Conventional range: DN15 ~ DN400
Typical examples: DN50, DN80, DN100, DN200
Nominal pressure (PN):
Low pressure system: PN10, PN16 (common in water supply and drainage networks)
Restrictions:
Not suitable for high pressure, high temperature or corrosive media
2. Ductile iron gate valve
Nominal diameter (DN):
Standard range: DN50 ~ DN600610
Special for gas: DN100 ~ DN300 (town gas pipeline)
Nominal pressure (PN):
Conventional pressure: PN10, PN16, PN25
Temperature limit: ≤120℃ (gas working conditions)
3. Cast steel gate valve
Nominal diameter (DN):
Extra wide coverage: DN10 ~ DN1200
Common caliber: DN50 ~ DN600 (industrial main process pipeline)
Nominal pressure (PN):
High pressure application: PN16 ~ PN100 (or American standard Class 150 ~ 2500)
High temperature resistance: Depends on material grade (such as WCB resistant to 425℃, WC9 resistant to 590℃)
4. Stainless steel gate valve
Nominal diameter (DN):
Full diameter coverage: DN15 ~ DN1000
Common in chemical industry: DN50 ~ DN300 (anti-corrosion demand scenario)
Nominal pressure (PN):
Multiple pressure levels: PN16 ~ PN40 (such as Z41W-16P type)
Material type: 304/316/316L (corrosion resistant, high temperature resistant).
Pipeline gate valve
Advantages
- Minimal fluid resistance : The straight-through flow channel design allows the medium to pass in a straight line, with low pressure drop and energy consumption.
- Small opening and closing torque : The vertical movement direction of the gate is perpendicular to the flow direction of the medium, and the operation is easy.
- Excellent sealing performance : When fully open, the sealing surface is less eroded by the medium and has a long service life; the risk of leakage after closing is low.
- Bidirectional sealing ability : Suitable for bidirectional flow pipe networks (such as ring network systems)
Limitations
- Large space requirements: High opening height (especially rising stem type), requiring a large installation space.
- Long opening and closing time: The gate needs to be raised and lowered throughout the entire process, and the speed is slower than the swing valve.
- Complicated maintenance: The double seal substructure is difficult to process and grind, and the maintenance cost is high.
- Not suitable for regulating flow: It is easy to scour the sealing surface when partially opened, causing wear or vibration.
Applications
- Long-distance transmission pipelines: Municipal pipelines: Water supply and drainage, gas transmission (requires low flow resistance and large-diameter cutting).
- Oil and gas pipelines: Cut-off valves for crude oil and refined oil trunk lines.
- Industrial systems: Power stations: High-temperature and high-pressure steam pipelines (depending on material resistance).
- Chemical equipment: Process pipelines with clear full-open/full-close requirements.
- Fire protection system: Fire pump outlet pipeline (requires fast and reliable cutting)
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