What is the Floating Ball Valve?
A floating ball valve is a quarter-turn valve that applies a ball-shaped disk to control fluid flow. The ball is suspended by two valve seats that provide a seal against leakage. When the valve is opened, the ball turns to allow the fluid to flow through the pipeline. Yet, when the valve is closed, the ball turns back into place to stop the flow.
The term “floating” refers to the fact that the ball is not fixed. It is free to move slightly in response to changes in pressure or temperature. This allows the valve to maintain a tight seal even in high-pressure or high-temperature environments.
What are Trunnion Ball Valves?
A trunnion ball valve is a kind of valve used to regulate fluid flow in pipelines. The valve has a spherical or ball-shaped body. This can rotate around a fixed axis of the trunnion. This fixed axis of the trunnion helps to support the ball’s weight. Moreover, it also reduces friction during operation.
Floating Ball Valve vs. Trunnion Ball Valve: What is the Difference
How does the Floating Ball Valve work?
The valve has a spherical or ball-shaped body, free to move within the chamber. The ball is connected to the valve’s stem by a set of floating seats or springs positioned on either side of the ball. The stem extends from the ball through the top of the valve, which is connected to an actuator or handle. This can control the valve’s operation. When the valve is not opened, the ball is pressed against the valve seats, creating a tight seal. It prevents fluid from passing through.
When the valve is opened, the stem is rotated, causing the ball to move away from the valve seats. As the fluid flows through the valve, it exerts pressure on the ball, causing it to move slightly and remain centered in the valve chamber. This allows the valve to maintain a tight seal, even under high-pressure conditions.
How Does the Trunnion Ball Valve Work?
The valve consists of a hollow ball with a hole in the center. The ball is connected to two or more stem-like trunnions that protrude from the valve’s body. These trunnions are anchored to the valve body, which allows the ball to rotate while maintaining a tight seal.
When the valve is not open, the ball is rotated to align the hole in the ball with the pipe orifice, allowing fluid to pass through. When the valve is opened, the ball is rotated 90 degrees, closing off the pipe orifice and preventing fluid flow.
The trunnion mechanism in the valve helps to support the ball’s weight. Moreover, it reduces friction during operation. The trunnions also provide a fixed axis for the ball to rotate around. This will help to maintain alignment and prevent damage to the valve seats.
Floating Ball Valve Vs. Trunnion Ball Valve: Design
Floating Ball Valve Design
A floating ball valve typically consists of the following components:
The valve body is the main structure of this valve. It holds the ball, stems, and other internal components. The body is designed to withstand high pressure and temperature. The body of the floating ball valve is made from various materials such as carbon steel, stainless steel, and cast iron.
The valve seats are located on both sides of the ball. Its purpose is to provide a seal against the ball. The seats are made from a material such as PTFE or reinforced graphite. This material prevents damage to the ball and provides a tight seal.
The ball is a spherical or cylindrical-shaped part of the floating ball valve. It controls the flow of fluid through the valve. The ball is usually made from a rigid material, such as stainless steel, brass, or chrome-plated steel. However, it is designed to fit tightly against the valve seats to prevent leakage.
The stem is an extended, slender component that connects the ball to the handle or actuator. The stem is made from stainless steel or a similar material. It is designed to withstand the forces generated during operation.
- Handle or Actuator:
The handle or actuator is used to control the opening and closing of the valve. The handle is manually operated, while the actuator can be electric or pneumatic, depending on the application.
Design of Trunnion Ball Valve
The valve body is the casing that holds the valve in place. It provides support for the ball valves inside. This design can be constructed from various materials, depending on its application.
- carbon steel
- low-temperature carbon steel
- stainless steel
- super duplex
This is a disc in the shape of a sphere ball that rotates to stop or begin flow in a rotating motion. It is attached at one end to the trunnion and the other to the stem. The ball remains stationary while rotating. The seats of the trunnion ball valve are frequently in touch with this ball, which decreases the torque.
The Trunnion ball valve’s seat is a design element encompassing the ball. When the actuator is activated, the seats hold the ball firmly, preventing access. There are two varieties, namely metal and soft (Teflon). This causes the object to move toward the ball.
A trunnion ball valve has an additional shaft that holds the ball in place from below. This straight shaft is the trunnion. Its purpose is to keep the ball securely in place. In some trunnion-mounted ball valves, the trunnion is an extension of the spherical ball. In others, it is welded to the spherical ball disc.
Floating Ball Valve Vs. Trunnion Ball Valve: Material
Depending on the specific application and operating conditions, floating and trunnion ball valves can be made from various materials. However, there are some differences in the choice of materials between the two valve types due to their design and construction.
Floating ball valves typically have a more straightforward design and require less material than trunnions. As a result, floating ball valves can be made from a broader range of materials, including carbon steel, stainless steel, brass, and various alloys.
On the other hand, trunnion ball valves have a more complex design and require more materials to construct. As a result, trunnion ball valves are typically made from more robust materials, such as high-grade stainless steel, super Duplex or Duplex stainless steel, or other alloys that can withstand high-pressure and high-temperature applications. The seats in trunnion ball valves may also be made from metal alloys, such as Inconel or Monel, to withstand high-temperature and high-pressure conditions.
Trunnion ball valve vs. floating ball valve: Advantages
Advantages of Trunnion Ball Valve:
Higher Pressure and Temperature Ratings:
Trunnion ball valves are designed to handle higher pressure and temperature ratings than floating ball valves, making them suitable for high-pressure applications such as oil and gas pipelines.
The trunnion design allows the ball to pivot on two points, which reduces the operating torque required to turn the valve. This feature makes it easier to operate the valve, especially in large sizes.
Better Sealing Performance:
Trunnion ball valves have a better sealing performance due to the trunnion-mounted design. Two trunnions hold the ball in place, which provides excellent stability and prevents the ball from shifting, ensuring a tight seal.
Advantages of Floating Ball Valve:
- Lower Cost:
Floating ball valves are generally less expensive than trunnion ball valves, making them more cost-effective for low-pressure applications.
- Easy Maintenance:
Floating ball valves are easier to maintain than trunnion ball valves. The ball and stem can be easily removed from the valve body for inspection and repair.
- Quick Operation:
Floating ball valves are designed for quick and easy operation, making them suitable for fast-operation applications.
- Better Flow Control:
Floating ball valves offer better flow control than trunnion ball valves due to the full-port design, which reduces turbulence and pressure drop.