As a supplier of floating ball valves, I often encounter inquiries from customers about the differences between floating ball valves and trunnion ball valves. Understanding these differences is crucial for selecting the right valve for specific applications. In this blog, I'll delve into the characteristics, advantages, and suitable scenarios of both types of ball valves to help you make an informed decision.
Structural Differences
The most fundamental difference between floating ball valves and trunnion ball valves lies in their structural design.
Floating Ball Valve
In a floating ball valve, the ball is not fixed axially and is "floating" within the valve body. The ball is held in place by the valve seats on both sides. When the valve is closed, the pressure of the fluid in the pipeline pushes the ball against the downstream valve seat, creating a tight seal. This design allows for a relatively simple structure and is suitable for applications with lower to medium pressure. For instance, in a small - scale water supply system, a floating ball valve can effectively control the flow of water due to its straightforward sealing mechanism.
There are two main types of floating ball valves in our product range: the Floating Soft Seat Ball Valve and the Floating Metal Seat Ball Valve. The soft - seat version is often used in applications where a tight shut - off is required, such as in the food and beverage industry to prevent leakage of liquids. The metal - seat floating ball valve, on the other hand, is more suitable for high - temperature and abrasive media, like in some chemical processing plants.
Trunnion Ball Valve
A trunnion ball valve has a different structure. The ball in a trunnion ball valve is fixed by a trunnion, which is a shaft or a pivot at the top and bottom of the ball. This design allows the trunnion to absorb part of the force exerted by the fluid pressure, reducing the load on the valve seats. As a result, trunnion ball valves can handle much higher pressures compared to floating ball valves. In large - scale oil and gas pipelines where the pressure can be extremely high, trunnion ball valves are the preferred choice.
Sealing Mechanisms
The sealing mechanisms of these two types of ball valves also vary significantly.
Floating Ball Valve
The sealing of a floating ball valve relies on the deformation of the valve seats and the pressure of the fluid to press the ball against the seat. The soft - seat floating ball valve can achieve a very tight seal because the soft material of the seat can conform to the surface of the ball, filling any small irregularities. However, the soft seat may be subject to wear over time, especially when dealing with abrasive media. The metal - seat floating ball valve provides better resistance to wear and high temperatures but may not offer the same level of tight sealing as the soft - seat version in some cases.
Trunnion Ball Valve
Trunnion ball valves use a combination of the trunnion support and the valve seats for sealing. The trunnion helps to maintain the position of the ball accurately, and the valve seats are designed to provide a reliable seal even under high - pressure conditions. Since the trunnion takes on a significant portion of the pressure load, the valve seats experience less stress, which can result in a longer service life for the sealing components.
Advantages and Disadvantages
Each type of ball valve has its own set of advantages and disadvantages.
Floating Ball Valve
Advantages:
- Simple Structure: The floating ball valve has a relatively simple design, which makes it easier and more cost - effective to manufacture. This simplicity also means that it is generally more compact, making it suitable for applications where space is limited.
- Good Sealing at Low to Medium Pressures: As mentioned earlier, floating ball valves can provide a tight seal at low to medium pressures, especially with soft - seat designs.
- Lower Cost: Due to its simpler structure and manufacturing process, floating ball valves are usually more affordable than trunnion ball valves.
Disadvantages:
- Limited Pressure Capacity: Floating ball valves are not suitable for extremely high - pressure applications because the ball may be pushed too hard against the seat, causing excessive wear or even damage to the seat.
- Shorter Service Life in Harsh Environments: In applications with abrasive or high - temperature media, the valve seats of floating ball valves may wear out more quickly, reducing the service life of the valve.
Trunnion Ball Valve
Advantages:
- High - Pressure Resistance: Trunnion ball valves are designed to handle high pressures effectively. They can be used in large - scale industrial pipelines, such as those in the oil and gas industry, where pressures can reach several thousand pounds per square inch.
- Longer Service Life: The trunnion support reduces the stress on the valve seats, which can result in a longer service life, especially in harsh operating conditions.
- Better Performance in Large - Sized Applications: Trunnion ball valves are often preferred for large - diameter valves because they can maintain a reliable seal even as the size of the valve increases.
Disadvantages:
- Higher Cost: The more complex design and manufacturing process of trunnion ball valves make them more expensive than floating ball valves.
- Larger Size and Weight: Trunnion ball valves are generally larger and heavier than floating ball valves, which may require more space and stronger support structures for installation.
Application Scenarios
The choice between a floating ball valve and a trunnion ball valve depends largely on the specific application requirements.
Floating Ball Valve
- Water Supply and Drainage Systems: In municipal water supply and drainage networks, floating ball valves are commonly used due to their relatively low cost and good sealing performance at the operating pressures of these systems.
- Food and Beverage Industry: The soft - seat floating ball valves are ideal for applications in the food and beverage industry because they can provide a hygienic and tight seal, preventing the leakage of liquids and ensuring product quality.
- Small - Scale Chemical Processing: For small - scale chemical processing plants where the pressure is not extremely high, floating ball valves can be a cost - effective solution for controlling the flow of various chemicals.
Trunnion Ball Valve
- Oil and Gas Industry: In upstream, midstream, and downstream oil and gas operations, trunnion ball valves are widely used in pipelines, refineries, and storage facilities. They can withstand the high pressures and harsh environments associated with these applications.
- Power Generation: Trunnion ball valves are also used in power generation plants, especially in high - pressure steam and water systems, to control the flow of fluids safely and reliably.
- Large - Scale Industrial Pipelines: Any large - scale industrial pipeline that requires high - pressure operation, such as those in the petrochemical and mining industries, will often use trunnion ball valves.
Conclusion
In conclusion, the choice between a floating ball valve and a trunnion ball valve depends on various factors, including the pressure requirements, the nature of the fluid, the operating environment, and the budget. As a supplier of floating ball valves, I understand the importance of providing the right valve for each customer's specific needs. If you are still unsure which type of ball valve is suitable for your application, I encourage you to contact us for professional advice. We have a team of experts who can help you select the most appropriate valve and provide you with detailed information about our products. Whether you need a floating ball valve for a small - scale project or a trunnion ball valve for a large - scale industrial application, we are here to assist you. Contact us today to start a procurement discussion and find the perfect ball valve solution for your needs.
References
- Valve Handbook, 4th Edition, by J. S. T. Lovick
- Industrial Valves: Selection and Application, by J. M. Munson