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Description:
Gate Valve, so-called Sluice Valve, is a valve that opens by lifting a barrier out of the fluid path. The gate valve needs very less space along the pipeline axis, and the flow of fluid is hardly restricted when the gate is fully opened or fully closed. The gate faces are generally wedge-shaped as they are able to apply pressure on the sealing surface, but they can be parallel faces as well. The main purpose is to prevent fluid flow, when the fluid starts and stops in the piping system, the disc moves perpendicular to the direction of flow. The valve stem and handwheel rotate clockwise to open (CTO) / clockwise to close (CTC) to operate the gate valve. The main components of a gate valve include valve body, seat, wedge, stem, gasket, handwheel, and bonnet. |
Brand:
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CATALOGUE
- ANSI 150# SS316 Gate Valves >
- JIS 10K SS316 Gate Valves >
- Threaded End SS316 Gate Valves (200 PSI) >
- Threaded End SS316 Gate Valves (800 PSI) >
- ANSI 150# Cast Iron Gate Valves >
- JIS 10K Cast Iron Gate Valves >
- ANSI 150# Cast Steel Gate Valves >
- ANSI 150# Forged Steel Gate Valves >
- Threaded End Forged Steel Gate Valves >
- Welded End Forged Steel Gate Valves >
LITERATURE
- ANSI 150# SS316 Gate Valves >
- JIS 10K SS316 Gate Valves >
- Threaded End SS316 Gate Valves (200 PSI) >
- Threaded End SS316 Gate Valves (800 PSI) >
- ANSI 150# Cast Iron Gate Valves >
- JIS 10K Cast Iron Gate Valves >
- ANSI 150# Cast Steel Gate Valves >
- ANSI 150# Forged Steel Gate Valves >
- Threaded End Forged Steel Gate Valves >
- Welded End Forged Steel Gate Valves >
Different Types of Gate Valves
Product Information of Gate Valves
1. What is a Gate Valve used for?
The usage of a Gate Valve is to close the flow of liquid rather than to regulate the flow. The typical gate valve has no obstacles in the flow path when it is fully opened, resulting in very low flow resistance. When the gate is moved, the size of the open flow channel commonly changes in a non-linear manner, which means the flow rate will not change evenly with the valve stem stroke. It is still depending on the construction, a partially open gate may vibrate due to fluid flow.
Generally speaking, gate valves are mainly used for larger pipe diameters (from 2” to the largest pipes) because their construction is less complex than other types of large size valves. Under high pressure, the friction can lead to a problem. As the pressure of the medium pushes the gate toward its guide rail, resulting in difficulty to operate the valve. Besides, a large gate valve is usually allocated with a bypass controlled by a smaller valve to decrease the pressure before the gate valve works. Gate valves without additional sealing rings on the gate / the seat are used in applications where slight valve leakage is not a problem, including heating circuits or sewer pipes.
In addition, gate valves cannot be applicable as control or regulating valves, this is because the accuracy of flow control is not achieved. High-speed flow in partially opened valves is discouraged. It may corrode the surface of the valve seat and the valve disc, which may cause vibration and noise.
The usage of a Gate Valve is to close the flow of liquid rather than to regulate the flow. The typical gate valve has no obstacles in the flow path when it is fully opened, resulting in very low flow resistance. When the gate is moved, the size of the open flow channel commonly changes in a non-linear manner, which means the flow rate will not change evenly with the valve stem stroke. It is still depending on the construction, a partially open gate may vibrate due to fluid flow.
Generally speaking, gate valves are mainly used for larger pipe diameters (from 2” to the largest pipes) because their construction is less complex than other types of large size valves. Under high pressure, the friction can lead to a problem. As the pressure of the medium pushes the gate toward its guide rail, resulting in difficulty to operate the valve. Besides, a large gate valve is usually allocated with a bypass controlled by a smaller valve to decrease the pressure before the gate valve works. Gate valves without additional sealing rings on the gate / the seat are used in applications where slight valve leakage is not a problem, including heating circuits or sewer pipes.
In addition, gate valves cannot be applicable as control or regulating valves, this is because the accuracy of flow control is not achieved. High-speed flow in partially opened valves is discouraged. It may corrode the surface of the valve seat and the valve disc, which may cause vibration and noise.
2. Types of body Gate Valve
There is a variety of options for body gate valve:
A. Body Bonnet Joint
I. Screwed bonnet
- Economical option.
- Less complex valve design
II. Bolted bonnet
- Common used and a large number of designs.
- A gasket is required to seal the joint between the valve body and the bonnet.
III. Welded bonnet
- Popular design without disassembly.
- Lighter than bolted bonnet counterparts.
IV. Pressure sealed bonnet
- Applied to a high pressure system.
- Suitable for high temperature applications.
- The higher the body cavity pressure, the greater the force acting on the gasket in the pressure seal.
B. Disc Type
I. Split wedge / parallel disc valve
II. Solid taper wedge
III. Flexible wedge
C. Stem Movement Type
I. Rising stem or OS & Y type (Screw end type & outside stem)
II. Non-rising stem type
There is a variety of options for body gate valve:
A. Body Bonnet Joint
I. Screwed bonnet
- Economical option.
- Less complex valve design
II. Bolted bonnet
- Common used and a large number of designs.
- A gasket is required to seal the joint between the valve body and the bonnet.
III. Welded bonnet
- Popular design without disassembly.
- Lighter than bolted bonnet counterparts.
IV. Pressure sealed bonnet
- Applied to a high pressure system.
- Suitable for high temperature applications.
- The higher the body cavity pressure, the greater the force acting on the gasket in the pressure seal.
B. Disc Type
I. Split wedge / parallel disc valve
II. Solid taper wedge
III. Flexible wedge
C. Stem Movement Type
I. Rising stem or OS & Y type (Screw end type & outside stem)
II. Non-rising stem type
3. How many types of Gate Valves are there:
- Solid taper wedge: Because of its strength and simplicity, a solid taper wedge is the most generally used disc type gate valve. It can be installed in any position and application for all types of fluids. Nonetheless, the pipe loads or thermal expansion results cannot compensate in aligning to changes in seat alignment. The disc design is the easiest to leak. The solid wedge is thermally locked for application under high temperature environments, where thermal locking is a phenomenon in which a wedge gets stuck between valve seats and leads the metal to expand. Therefore, solid wedge gate valves are often used in low and medium pressure temperature applications.
- Flexible wedge: A solid disc with cutouts on the periphery. The cut varies in terms of size, depth, and shape. The shallow and narrow cuts around the wedge preserve strength and reduce flexibility. Cast grooves or wider and deeper cuts on the wedge perimeter provide greater flexibility. In addition, it also provides better sealing and improves valve seat alignment, it also enhances the performance of thermal binding. Thermal binding is a phenomenon where the wedge gets stuck in a closed position. The main reason is due to the relatively cold valve stem being inserted into a hot valve, and the valve stem heats up, thereby further increasing the seating force after the torque is turned off. When the valve body cools down, the valve seat contact on the valve wedges, locking them in place. Hence, flexible wedges are generally used in steam system applications. The disadvantage of flexible wedges is that line fluids tend to accumulate in the disc and cause corrosion and ultimately undermine the disc.
- Split wedge or parallel disc valve: The split wedge disc consists of two solid pieces, which are fixed to each other with the help of a special mechanism. In the case that half of the disc is not aligned, the other half of the disc can be adjusted freely according to the seat surface. The split disc can be in a parallel disc or wedge-shaped, where parallel discs adopt a spring-loaded design, and they contact the valve seat to provide a two-way direction sealing; whereas splitting wedges are usually utilized to deal with non-condensable gases and liquids at room temperature or high temperature. Even though the valve may be closed when the pipeline is cold, the movement of the valve disc can avoid thermal bonding. This means that when the line is heated by fluid and expands, it does not produce thermal bonding.
ANSI 150# SS316 Flange End Gate Valve
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4. What is the Stem Movement Type?
Gate valves are categorized into two types, which are rising stem and non-rising stem types. The rising stem gate valve can track the opening or closing position through the up and down movement of the valve stem. When the valve is in the open position, the valve stem will go up; when the valve is closed, it will move downward. It provides a visual indication of the valve position and can lubricate the valve stem. The valve type is only appropriate for installation on the ground, the nut rotates around the threaded stem and moves it. The valve closes when the valve stem cannot be viewed above the control wheel and opens when the threaded stem extends from the top of the wheel. It is called OS&Y valve, which means external stem and yoke or external thread and yoke. The non-rising stem gate valve does not perform upward movement of the stem. The disc is threaded inside and moves along the stem while the wheel and valve stem are rotated. As the steam threads are bare to the flow medium, and the valve is purposely used in a limited space, therefore it allows linear steam movement. The flow medium will not result in corrosion or erosion. Rising stem vs Non-rising stem The key difference between the rising stem and the non-rising stem gate valve is the appearance of the rising stem gate valve. It can be observed from the appearance to see whether the valve is closed or open. The lead of the stem is the part to be identified. |
5. How long does a gate valve last?
The gate valve has a small disc inside the valve. When the valve handle is turned, it will move to control the fluid flow. As time increases, the performance of the valve may drop and tends to stick. When the valve is fully closed, water will usually still flow through because the valve flap is stuck in the open position. If the valve is indeed closed, when the handle returns to the open position, the disc will sometimes get stuck in the closed position.
Wear and corrosion are other common causes of gate valve failure. When the gate valves have been used for a longer year, they tend to wear out; whereas corrosion can result in the disc getting stuck in the open or closed position. The stem leading from the handle to the disc usually can be fractured when the valve handle is forced, making the gate valve no longer functioned.
The gate valve has a small disc inside the valve. When the valve handle is turned, it will move to control the fluid flow. As time increases, the performance of the valve may drop and tends to stick. When the valve is fully closed, water will usually still flow through because the valve flap is stuck in the open position. If the valve is indeed closed, when the handle returns to the open position, the disc will sometimes get stuck in the closed position.
Wear and corrosion are other common causes of gate valve failure. When the gate valves have been used for a longer year, they tend to wear out; whereas corrosion can result in the disc getting stuck in the open or closed position. The stem leading from the handle to the disc usually can be fractured when the valve handle is forced, making the gate valve no longer functioned.
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