In industrial piping systems, valves are indispensable components that control the flow of fluids and ensure the safe and efficient operation of the system. The wedge gate valve, as a common type of valve, plays a significant role in numerous industrial fields due to its unique structure and reliable performance. This article will provide a detailed introduction to the structural characteristics, working principles, advantages and disadvantages, and applicable scenarios of wedge gate valves, helping readers gain a comprehensive understanding of this important industrial valve.
The wedge gate valve gets its name from the angle between its sealing surface and the vertical centerline, meaning the two sealing surfaces form a wedge shape. This structure allows the wedge gate valve to achieve a tighter seal when closed, effectively preventing fluid leakage. A typical wedge gate valve consists of a valve body, valve seat, gate, and stem. Among these, the gate is the key component of the wedge gate valve, moving perpendicularly to the fluid direction to open and close the valve.
Valve Body: The valve body is the main part of the wedge gate valve, providing the foundation for the installation and support of other components. It is usually made of corrosion-resistant and wear-resistant materials to ensure the valve's performance in harsh working environments.
Valve Seat: The valve seat is the key component that cooperates with the gate to achieve sealing. It is typically made by hard face with hard alloy to enhance its wear, high-temperature, and corrosion resistance.
Gate: The gate is the core component of the wedge gate valve, with a wedge shape and a certain angle θ between the sealing surfaces and the vertical centerline of the gate, known as the wedge half-angle. Common wedge half-angles are 2°52' and 5°. The size of the wedge half-angle significantly affects the valve's performance. A smaller angle reduces the force required to close the valve, but it increases the likelihood of the wedge gate being wedged in the valve body due to pipe deformation caused by temperature changes.
Stem: The stem moves up and down to drive the gate, enabling the valve's opening and closing. It is usually made of high-strength material to ensure it does not deform or get damaged during operation.
The sealing principle of the wedge gate valve involves the stem driving the gate to move up and down, causing the gate to closely adhere to the valve seat, thereby forming a reliable seal. When the valve is closed, the sealing surfaces of the gate and valve seat make tight contact, creating a sealing pressure to prevent fluid leakage. When the valve is opened, the gate moves upward, allowing the fluid passage to be unobstructed.
The valve body of the wedge gate valve is equipped with a guiding mechanism that prevents the gate from rotating during opening or closing. This ensures the alignment of the sealing surfaces and prevents the gate from rubbing against the valve seat before it reaches the closed position, reducing wear on the sealing surfaces.
The wedge gate valve controls its opening and closing by the stem driving the gate to move up and down. When the valve is closed, the gate tightly adheres to the valve seat, forming a reliable seal; when the valve is opened, the gate moves upward, allowing the fluid passage to be unobstructed. It is important to note that wedge gate valves are designed for full open and full close operations and are not suitable for regulating or throttling purposes.
Initial Position: The valve is fully open, with the gate located at the upper part of the valve body, allowing the fluid passage to be completely unobstructed.
Closing Action: The gate gradually moves downward by rotating the stem.
Seal Contact: As the gate approaches the valve seat, the sealing surfaces of the gate and valve seat begin to make contact and gradually form a sealing pressure.
Final Closure: The gate fully adheres to the valve seat, creating a tight seal and completely cutting off the fluid passage.
Initial Position: The valve is fully closed, with the gate tightly adhering to the valve seat and the fluid passage completely cut off.
Opening Action: The gate gradually moves upward by rotating the stem.
Seal Separation: The sealing surfaces of the gate and valve seat gradually separate, allowing the fluid passage to begin to open.
Final Opening: The gate fully leaves the valve seat, making the fluid passage completely unobstructed.
As a widely used industrial valve, the wedge gate valve has a unique structure and working principle that enable it to perform well in various operating conditions. However, like any industrial equipment, it also has its own strengths and limitations. The following will provide a detailed discussion of the advantages and disadvantages of wedge gate valves to better understand their performance in practical applications.
Good Sealing Performance: The wedge structure allows the gate to closely adhere to the valve seat, forming a reliable seal that effectively prevents fluid leakage.
Wide Applicability: Wedge gate valves can be used with various media, including water, steam, and oils, and are suitable for a range of operating conditions from low-temperature, low-pressure to high-temperature, high-pressure applications.
Simple Structure: Particularly for single-gate designs, the structure is simple, making manufacturing and maintenance relatively easy.
Flexible Gate Design: The flexible gate can adapt to temperature changes and is less likely to be wedged, enhancing the valve's reliability and service life.
High Torque: Since the valve relies on the stem to push the gate downward to achieve sealing, the operating torque of the wedge gate valve is relatively high, requiring a greater operating force.
Particle Medium Issues: During closure, particle media may enter the sealing surfaces, leading to poor sealing and potential damage to the sealing surfaces.
Temperature Rise Issues: When the temperature rises excessively in the closed state, the stem may expand due to heat, causing the gate to become stuck.
Complex Electric Actuator: The electric actuator for wedge gate valves is relatively complex because it limits torque rather than travel. The actuator must have sufficient torque margin to ensure the valve can open under full pressure differential and to account for the increased opening and closing torque due to thermal expansion of the valve components.
Wedge gate valves can be categorized into various types based on their structure and function. Each type has its unique characteristics and suitable applications. The following will introduce several common types of wedge gate valves in detail.
The flexible gate wedge gate valve features a simple structure and reliable sealing. It is less prone to wedging due to temperature changes in the medium. The single-piece flexible gate, supported by a central cantilever beam, has a circular groove on its mid-plane that provides flexibility. When closed, the gate's slight deformation compensates for manufacturing deviations, ensuring a tight seal with the valve seats. This design prevents wedging caused by thermal expansion or valve body deformation. Suitable for medium and small-sized valves with various pressures and temperatures, it should not be used with media containing excessive solid particles to avoid clogging the gate's groove.
The rigid gate wedge gate valve has a solid, single-piece structure that cannot compensate for valve seat misalignment due to pipeline loads or thermal fluctuations. The high processing accuracy required for the wedge half-angle on both sealing surfaces makes manufacturing and maintenance more difficult. During operation, wear between sealing pairs is common, and the gate is susceptible to wedging with temperature changes. For sizes larger than DN50 (NPS2), it is not recommended for temperatures exceeding 121°C (250°F). However, it is the most economical option for small gate valves up to DN50 (NPS2), suitable for lower "pressure-temperature" conditions.
The double gate wedge gate valve combines two gates hinged into a wedge shape by a spherical center. This design allows the gate to adjust its angle for better mating with both valve seats. The spherical center automatically adjusts the sealing wedge angle, reducing processing accuracy requirements. The gate is less likely to stick or scratch with temperature changes, and wear can be compensated by adding shims at the center. However, the complex structure with more parts makes it unsuitable for viscous media and prone to gate detachment due to rusting. Typically installed vertically in water and steam pipelines, it addresses issues like valve body twisting and temperature-induced wedging. Suitable for sizes DN50 to 600 (NPS12 to 24), it uses materials like carbon steel, chromium-molybdenum steel, stainless steel, duplex stainless steel, and nickel alloy, with an operating temperature range of -196°C to 816°C.
Both wedge gate valves and parallel gate valves are commonly used valve types in industrial piping systems, each with its unique structural and performance characteristics. Understanding the differences between these two types of valves is crucial when selecting the appropriate valve. The following will provide a detailed comparison of wedge gate valves and parallel gate valves from various aspects to help readers better choose the suitable valve type.
Wedge Gate Valve: The gate is wedge-shaped, with the sealing surfaces on both sides having a certain angle with the vertical centerline. This design allows the valve to form a tighter seal when closed.
Parallel Gate Valve: The gate is flat and may have flow holes, which facilitate pigging operations. The sealing surfaces of the gate and valve seat of the parallel gate valve are always in contact, preventing particles in the medium from entering the sealing surfaces. Therefore, it is more suitable for applications with particulate media.
Wedge Gate Valve: It relies on the stem pushing the wedge-shaped gate downward to achieve forced sealing, resulting in a higher torque. The torque switch controls the closure, requiring a certain torque to maintain the stem's pushing force on the gate and to produce a sealing pressure on the valve seat.
Parallel Gate Valve: It relies on the medium pressure to press the gate against the valve seat to complete the sealing, with a smaller torque on the stem. The travel switch controls the closure, requiring only the control of the gate's position.
Wedge Gate Valve:
Advantages: Good sealing performance, wide applicability, simple structure, and the flexible gate design adapts to temperature changes.
Disadvantages: High torque, particles may enter the sealing surface, temperature rise may cause the gate to stick, and the electric actuator is complex.
Parallel Gate Valve:
Advantages: Smaller stem torque, easy operation, the gate and valve seat are always in tight contact, particles are less likely to enter, good sealing performance, suitable for applications with particulate media, the stem has a protective cover, and a longer service life.
Disadvantages: Relatively complex structure, especially the design with flow holes, which requires regular greasing maintenance and increases maintenance costs.
Wedge Gate Valve: Suitable for medium and small-sized piping systems, especially in applications requiring reliable sealing and the ability to adapt to temperature changes. It is widely used in pipelines carrying water, steam, oils, and other media.
Parallel Gate Valve: Suitable for medium and low-pressure, large and medium-sized piping systems for oils or coal gas, natural gas, and other applications, particularly those with particulate media, such as in the petroleum, chemical, and natural gas industries.
To ensure the long-term stable operation of wedge gate valves, regular maintenance and care are essential. The following are some common maintenance and care measures.
Sealing Performance: Regularly inspect the valve's sealing performance to ensure that the sealing surfaces between the gate and valve seat are not worn or damaged.
Stem Condition: Check if the stem is deformed or damaged to ensure it can move up and down smoothly.
Guiding Mechanism: Inspect whether the guiding mechanism is functioning properly to prevent the gate from rotating during opening or closing.
Cleaning: Regularly clean the exterior and interior of the valve, especially the sealing surfaces and stem, to prevent the accumulation of dust and impurities.
Lubrication: Regularly lubricate the stem and guiding mechanism to reduce friction and extend the valve's service life.
Avoid Over-Operation: When operating the valve, avoid excessive force to prevent damage to the stem and gate.
Temperature Control: When used in high-temperature environments, pay attention to the impact of temperature changes on the valve to prevent the gate from being wedged.
Worn Parts Replacement: If the gate, valve seat, or other components are severely worn, they should be replaced in a timely manner to ensure the valve's sealing performance.
Professional Repair: For complex repair work, it is recommended to contact professional maintenance personnel to ensure the quality of the repair.
As an important industrial valve, the wedge gate valve plays a significant role in various industrial applications due to its unique structure and reliable performance. Its wedge design enables the valve to form a tighter seal when closed, effectively preventing fluid leakage. Although the wedge gate valve has some drawbacks, such as high torque and the potential for particles to enter the sealing surface, these can be effectively managed through proper maintenance and care. When selecting a valve, one should consider the specific operating requirements and weigh the characteristics of wedge gate valves and parallel gate valves to choose the most suitable type to ensure the safe and efficient operation of the system. Through the detailed introduction provided in this article, readers should have a comprehensive understanding of the wedge gate valve, including its structural characteristics, working principles, advantages and disadvantages, and applicable scenarios, which will help them make informed choices in practical applications.
Copyright © 2025 China Topper Valve Packing Seal Kits Co., Ltd. All Rights Reserved.