Valve selection is a very important step in the design of any fluid handling system because the wrong type of valve can lead to many problems. Among all the types of valves, the gate valve and the ball valve are two of the most commonly used valves in engineering and technology. Although both are used to control the flow of liquid, they differ in design, functionality, and application. It is crucial to understand these differences to achieve the best results in terms of system performance, productivity, and safety in numerous industries. This article will focus on the detailed description of gate valves and ball valves, which will help you make the right choice for your application.
What is a Gate Valve?
In its simplest form, a gate valve is a linear motion valve that opens or shuts off the water flow or any other fluid. Its main application is to open or shut the fluid flow completely, allowing a full bore flow when in the open position and no flow when closed. Some of the most common types of gate valves are the parallel slide gate valves, wedge gate valves (solid wedge, flexible wedge, and split wedge) and through-conduit gate valves, which are developed to meet different high pressure and temperature conditions.
What is a Ball Valve?
A ball valve is a type of rotary valve that rotates a quarter turn to open or close the valve with the help of a spherical disc having a hole in the center. Ball valves are characterized by their ability to shut off quickly, provide a tight seal, and are relatively small in size, making them suitable for use in water supply systems. There are several types of ball valves such as full port, reduced port, V-port, and trunnion-mounted ball valves, and each of them has different flow coefficients and pressure ratings. The main element is a hollow ball with a rotatable bore.
Gate Valve vs Ball Valve: How Do They Compare?
Working
Design and Structure
The structure of gate and ball valves also has some differences that can be outlined as follows: A gate valve is made up of body, bonnet, gate, seat rings, stem and actuator which could be handwheel or automatic. The gate slides along the stem with the help of the seat rings to regulate the flow. Ball valves, in contrast, are usually made up of a body, ball, seats, stem, and actuator. The ball with its unique bore is the main flow control component which rotates to either open or close the seats to allow or prevent the flow of fluids. Gate valves are generally larger and heavier than the ball valves of the same size and pressure class mainly due to the required space for the movement of the gate.
Flow Control
In the case of flow control, gate valves are mainly used for on-off applications in large water supply lines. They are not very effective in controlling or managing the flow. Some of the issues that may arise from partially opening a gate valve include flow induced vibration, erosion of the gate and seats due to the high velocity of the fluid passing through the restricted opening and valve damage. Ball valves are mainly used for on/off service but they can provide some measure of throttling especially when the ball has a V-shape port. But, throttling with a standard ball valve can also cause seat wear if it is done for a long time. In terms of flow control, the use of control valves is more recommended than both gate and ball valves.
Applications
Gate valves are used in those processes where there is a need for a large and free flow of the medium and where the valve is not frequently opened or closed. Examples include:
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Water and wastewater treatment plants
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Oil and gas pipelines
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Power plants
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Mining operations
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Bulk material handling
Ball valves due to their fast operation and ability to shut off and seal are used in a broad range of applications such as:
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HVAC systems
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Natural gas distribution
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Chemical processing
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Food and beverage industry
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Pharmaceuticals
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Automated process control systems
It mainly depends on the needs of the system, for instance, whether it requires quick closure, tight sealing, or low pressure drop.
Sealing Performance
Tightness is one of the most important aspects of valve performance, and both gate valves and ball valves have varying degrees of sealing. Ball valves, especially those with soft seats (PTFE or elastomer) are relatively more effective in terms of sealing than the gate valves. This is due to the spherical shape of the ball and the uniform contact with the seats along the sealing surface. Gate valves depend on the gate closing on the seats to create a seal. In the course of time, the sealing surfaces of the gate valves can be subjected to wear and tear depending on the frequency of use of the valve or if the fluid passing through the valve contains abrasive materials, which can cause leakage.
Service Life
The service life of both gate valves and ball valves depends on the material used in the valve, the working conditions (pressure, temperature, type of fluid), and usage frequency. In general, ball valves are less complex in design and have fewer parts that are in motion, and therefore, they are more likely to have a longer life cycle particularly in cycling services. The quarter turn operation also reduces the wear and tear of the internal parts. Gate valves, due to their sliver motion, can suffer more wear on the gate and seats especially if the valve is used for throttling. Nevertheless, in the cases when they are used mostly in the fully open or fully closed position and are not exposed to severe conditions, gate valves can also serve for a long time and ensure the durability of the system as a whole.
Maintenance and Cleaning
The maintenance of gate valves and ball valves is different because of the design of the two. Gate valves are generally more demanding in terms of maintenance because of the number of parts that move and the wear on the gate and seats. Maintenance of the spindle may require frequent lubrication while the packing may require inspection to check for any leakage. Cleaning can also be more complicated in gate valves because of the cavity that is usually available for debris to deposit, thus causing contamination. Ball valves are comparatively less complex and therefore, they need less maintenance. Nevertheless, the seats of ball valves can be worn out by abrasive fluids or high pressure. Cleaning a ball valve is usually easy, sometimes it only requires that the valve is opened and flushed.
Factors to Consider When Choosing Between Gate and Ball Valves
Fluid Type
The nature of the fluid that is to be managed by the system is a critical factor in the choice of the valve. For clean, non-viscous fluids, both gate and ball valves can be better choices. However, for fluids containing suspended solids or slurries, gate valves might be more susceptible to clogging or seat damage due to the sliding motion of the gate. Ball valves, which clean themselves as the ball turns, may be preferable in such applications. For highly corrosive fluids, the material of construction of the valve parts (body, seats, seals) is critical and both types of valves are made in various corrosion resistant materials and they can handle gasses.
Installation Space
The size of the installation space may also determine whether a gate or ball valve is used. Ball valves are generally more compact in design compared to gate valves of the same nominal size and pressure rating. This makes ball valves to be preferred in many systems since they require less installation space in many cases. Gate valves need more linear travel for the gate to be fully lifted when fully open and this may be a limitation in some applications.
Cost
The initial cost of gate valves and ball valves may differ depending on the size, pressure class, material of construction, and brand. In general, for the small sizes and low pressure class, the cost of ball valves may be slightly higher than the gate valves. But in the large sizes and high pressure classes, the cost difference may not be much and at times, the gate valves may be cheaper. The overall cost should also include the long-term costs such as the costs of maintaining the equipment and the costs of replacing the equipment in the near future.
Pressure
For the low to medium pressure ranging up to the ANSI Class 300, both gate and ball valves can be used, but the ball valves are more preferred due to the better sealing and quick operation. In high-pressure applications (ANSI Class 600+), the use of special designs is necessary for both. Gate valves are used for very high pressure applications, but there are high pressure ball valves with trunnion mounting as well. It is always important to ensure that the valve’s pressure rating is higher than the system’s maximum pressure and hydraulic shock.
Temperature
Another factor that influences the choice of the valve is the temperature of the fluid being handled. Gate valves and ball valves can be ordered with different materials for the body, seats, and seals that are suitable for different temperature ranges. Temperature plays a significant role in the performance and durability of the valve and therefore it can either be high or low. For instance, high temperatures may lead to the deterioration of some soft seat materials used in ball valves. The following table shows the approximate temperature limits for the most commonly used valve materials:
| Material | Typical Temperature Range (°C) | Typical Temperature Range (°F) |
| Carbon Steel | -29 to 427 | -20 to 800 |
| Stainless Steel | -196 to 538 | -320 to 1000 |
| PTFE (Teflon) | -200 to 260 | -328 to 500 |
| EPDM | -50 to 150 | -58 to 302 |
| Buna-N (Nitrile) | -40 to 121 | -40 to 250 |
Valve Actuation: The Next Step for Gate and Ball Valves
Although handwheel or lever operation is typical for gate and ball valves, there are many applications where remote or automatic control is necessary. This is where valve actuation comes into play. Pneumatic, electric, and hydraulic actuators can be used on both gate and ball valves. Pneumatic actuators work on the principle of compressed air to provide the necessary force to operate the valve, making it a cost effective and efficient solution for many applications. Electric actuators employ an electric motor to supply the required torque for the valve operation, and they are easy to interface with the control systems.
As a professional actuated valves manufacturer in China, Vincer is dedicated to offering the most innovative valve solutions. Our commitment to quality and safety is underscored by our various certifications, including CE, ISO9001:2015, FDA, and RoHS, demonstrating our adherence to European safety standards, international quality management systems, and strict safety and environmental regulations. Furthermore, our upgraded SIL certificate ensures our products meet rigorous safety integrity levels. We are dedicated to independent research, development, production, and marketing of electric and pneumatic gate and ball valves. Whether you need electric ball valves for accurate flow control or pneumatic gate valves for dependable shut-off, Vincer has a wide range of products to suit your needs.
Conclusion
Selecting the right valve is crucial for the success of any fluid handling system. The decision between these two types of valves depends on the nature of the application, the type of fluid, pressure, temperature, available space, cost, and whether the valve needs to be actuated. It is only by understanding the differences and the strengths of each that one can make the right choice of the valves and have a better and more efficient fluid handling system.