A flanged gate valve is a type of valve that uses a flange connection and controls the flow of fluid by opening and closing a gate. It is widely used in pipeline systems in the petroleum, chemical, power, and municipal industries. Its core function is to completely cut off or allow the flow of the medium through the vertical movement of the gate. It features reliable sealing, low flow resistance, and a wide pressure range, making it particularly suitable for applications requiring "fully open/fully closed" control.
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Flanged Gate Valve Technical parameters
Material:Carbon Steel (WCB, WCC for strength)
Size Range:2″ to 48″ (DN50-DN1200)
Connection Options:Flanged, Threaded (NPT, BSP), Butt Weld, Socket Weld
Working Pressure:Class 150 to Class 1500 (up to 2,500 psi / 172 bar)
Working Temperature:-29°C to 425°C
Sealing Options:Metal-to-Metal, Resilient Seat, Graphite, PTFE
Manufacturing Method:Cast, Forged, Machined
Applicable Medium:Water, Oil, Gas, Steam, Chemical Fluids
Manufacturing Standard:API 600, API 602, ASME B16.34, BS 5163, DIN 3352
Flanged Gate Valve Structure and Classification
Basic Structure
Imported flanged gate valves consist of a valve body, valve cover, gate, valve stem, valve seat, and actuation device (manual, electric, pneumatic, etc.). The valve body and valve cover are fastened together with flange bolts to form a sealed cavity; the gate, as the opening and closing element, fits tightly with the valve seat to achieve a seal; the valve stem connects the gate and the actuation device, transmitting operating force.
Gate Types
Rigid Gate: Simple structure, suitable for normal temperature and low pressure conditions, but the sealing surface is prone to wear.
Resilient Gate: Compensates for sealing surface wear through slight elastic deformation of the gate, suitable for high temperature, high pressure, or media containing particles.
Wedge Gate: Divided into single-wedge and double-wedge types. Single-wedge is suitable for low pressure, while double-wedge automatically adjusts the sealing pressure through the wedge angle, adapting to high-pressure conditions.
Connection and Actuation Methods
Flanged Connection: Standard flanges conform to national standards such as GB/T 12237, ensuring secure installation and sealing, suitable for large-diameter, high-pressure pipelines. Drive method: Manual operation involves rotating the valve stem via a handwheel or handle; electric/pneumatic drive enables remote control via an actuator, offering fast response and suitability for automation systems.
Flanged Gate Valve Working Principle and Operation Logic
Opening Process
Rotate the handwheel or start the electric actuator. The valve stem moves the gate upward. When the gate is fully out of the valve body passage, fluid resistance is minimized (flow resistance coefficient is 1.5-2 times that of a butterfly valve of the same diameter), allowing the medium to pass smoothly. In actual operation, the fully open position of the valve is usually marked by the top of the valve stem, but it needs to be turned back 1/2-1 turn to prevent locking due to temperature changes.
Closing Process
Rotate the handwheel in the opposite direction or execute the closing command. The valve stem pushes the gate downward until it is tightly fitted with the valve seat. Resilient valve seats maintain sealing performance through automatic wear compensation, while hard seal structures (such as metal-face seals) rely on high-pressure forced sealing, suitable for flammable and explosive media.
Sealing Mechanism
Self-sealing: Relies on the medium pressure to press the gate against the valve seat, suitable for low-pressure conditions.
Forced sealing: Ensures sealing surface contact through external force (such as valve stem preload). Under high-pressure conditions, the sealing specific pressure can reach over 6MPa.
Soft seal: Made of elastic materials such as PTFE and EPDM, achieving zero leakage (ISO 15848-1 certified), suitable for clean fields such as food and medicine.
Applications
Energy Sector
Oil & Gas Extraction: Used in wellhead equipment, resistant to 10-35MPa high pressure and hydrogen sulfide corrosion, using 2507 super duplex stainless steel valve bodies.
Long-Distance Pipelines: DN500-DN1200 large-diameter valves equipped with electric drives, enabling emergency shutdown (response time ≤15 seconds).
Nuclear Power: Primary circuit main steam isolation valves in the nuclear island must meet ASME NPT nuclear grade certification, resistant to strong neutron radiation and 350℃ high temperature.
Industrial Manufacturing
Chemical Industry: Acid and alkali storage tank inlet and outlet valves use PTFE-lined imported flange gate valves, resistant to strong corrosion and with no risk of media contamination.
Metallurgy: Blast furnace gas pipelines use wear-resistant cast iron valve bodies with welded wear-resistant alloy sealing surfaces, adaptable to dusty gas erosion.
Semiconductors: Photoresist delivery pipelines use 316L EP grade stainless steel valve bodies, with inner walls electrolytically polished to Ra≤0.2μm to prevent particulate contamination.
Municipal and Environmental Protection
Waterworks: Ductile iron valve bodies paired with EPDM soft seals achieve zero leakage, reducing pipeline leakage rates.
Wastewater Treatment: Cast iron valve bodies with epoxy resin coating resist acid, alkali, and impurity erosion, preventing sludge deposition.
District Heating: Carbon steel valve bodies with metal hard seals prevent high-temperature hot water erosion that could lead to seal failure.
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