How Does a Forged Steel Gate Valve Work? - SIO
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How Does a Forged Steel Gate Valve Work?

15/09/2019
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Forged steel gate valves are the most commonly used linear motion valves in the piping industry. They are used to start or stop the flow of medium through pipes. The valves feature a gate as a disk that rises and falls to control the flow of medium. Gate valves are popularly used in different kinds of industries because they are versatile, easy to use, and durable.

Forged Steel Gate Valve
Forged steel gate valve

Forged steel gate valves can be constructed in many different ways making them suitable for various applications in any factory unit. They allow bi-directional flow and can be operated using manual and electric actuators. Gate valves are only used in fully open or fully closed positions. They cannot be used for throttling purposes. 

In this blog, we are going to share with you how forged steel gate valves are constructed and how they work. Read on!

How is Forged Steel Gate Valve Constructed?

Gate valves can have many different kinds of components. However, the basic structure of all gate valves remains the same. Every gate valve has three main parts: Body, Bonnet, and Trim. Take a look at the diagram below to see what a typical gate valve looks like. 

Diagram of a forged steel gate valve

Source: https://valveproducts.net/gate-valve/parts-of-a-gate-valve

Body

The body of the valve, also known as shell, is the first pressure boundary against onstream flow. In forged steel gate valves, the body is made of metal that is hot forged to get a more consistent, strong, and durable finish. Forged steel gate valves have improved strength and resilience characteristics than cast steel gate valves

Bonnet

The bonnet of a gate valve is the opening at the top of the body that can be removed to access the moving parts of the valve. The bonnet of forged steel gate valves can be welded, bolted, or pressure sealed to the body depending on the application. This is an important component of the valve since it determines how the valve will be repaired, maintained, or replaced. 

Trim

The trim of the gate valve features all the moving parts of the valve. The first part is the stem, which is connected to the actuator on one end and the disk on the other. It is responsible for moving the disk of the valve. The second part is the disk itself. In forged steel gate valves, the disk is in the form of a gate that can move upwards and downwards. It is usually made of steel or other durable materials. The last moving part of the trim is the seat of the valve. The seat partners with the disk or gate of the valve to provide a firm seal. The seat of a forged steel gate valve is either in a ‘V’ shape or in the shape of a pointed valley. 

How do Forged Steel Gate Valves Work?

Forged steel gate valves are popular in piping systems as they are easy to install and operate. They are mostly used to isolate certain areas in the piping system. For example, if you had to manage steam distribution in a power plant you will install a welded gate valve like the SIO Forged Steel Gate Valve

Diagram of the closed and open status of a forged steel gate valve

Source: https://hardatengineer.com

To open the valve, you will move the actuator one way which in turn will move the stem of the valve. SIO forged steel gate valves come with OS&Y (Outside Screw and Yoke) stems. This is a type of rising stem in which the threaded part of the stem is kept outside the fluid containment area. The stem is kept safe from corrosion from strong fluids. Also, OS&Y stems are not directly connected to the actuator. In fact, the actuator is connected to a bushing top at the top of the valve yoke. This means the actuator doesn’t move up or down as you open and close the valve saving both space and energy. 

Forged steel gate valve
Forged steel gate valve

As the stem rises, it lifts the connected gate so that the flow path is cleared. The gas can now easily flow from one end of the pipeline to the other. Flexible wedge gate forged steel valve or parallel disk forged steel gate valve are more suitable for steam and non-condensed gas. In the former, the gate has cut around the perimeter. These cuts improve seat alignment and provide greater protection against leakages. Parallel disk gate valves feature two solid pieces of disks that held together by a special mechanism. The seats in this valve are spring-loaded so they are always in contact with the gates providing bi-directional sealing. 

Forged steel gate valve
Forged steel gate valve

To stop the flow of gas, move the actuator in the opposite direction. The stem will rotate again, this time bringing the gate downwards to block the flow path of the medium. The onstream pressure will cause the seat to move towards the gate forming a firm seal. When it is fully open, the disk of the forged steel gate valve is completely removed allowing free flow of medium. Since there is no resistance to the flow, there is very little pressure drop as the medium passes through the gate valve. When fully closed, there is 360-degree surface contact between the disk and seat of the valve, making sure the valve is sealed properly. 

Forged Steel Gate Valve Applications

Forged steel gate valves are extremely versatile and can be used for many different kinds of applications in piping units. They can be used in high-temperature coking units, food and beverage factories,  pharmaceutical services, waterways and municipalities, drilling manifold systems, subsea manifolds, and more.

Forged steel gate valve
Forged steel gate valve

Welded forged steel gate valves can be used for standard and critical applications in the power industry. Smaller non-rising stem forged steel gate valves are suitable for wellhead manifold systems as the provide a reliable mechanical seal and can handle high-pressure operations. Forged steel double expanding gate valves can be used in pipeline applications where operational integrity is vital. Forged steel resilient gate valves are suitable for many different industrial and commercial applications.

Conclusion

Forged steel gate valves are sturdier and more durable than other kinds of gate valves. They can be used in high-temperature operations or for isolating critical areas in piping units. SIO offers forged steel gate valves class 800 and more. Our gate valves are API 602, ASME B16.34, and API 598 certified. If you’re looking to add any special features to your gate valves, get in touch with us. We will provide full OEM support for your project. 

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