Floating vs Trunnion Ball Valves: Structural Differences and Selection Guide
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Ball valves are essential control elements in pipeline systems, widely used in the regulation of flow and pressure for various liquids and gases. Based on the design and working principle of the ball core, ball valves are classified into floating ball valves and trunnion-mounted (fixed) ball valves. Each type has its unique structural characteristics, suitability for different working conditions.
This article compares the structural features of floating ball valves and fixed ball valves, analyzing their differences in sealing methods, applicable working conditions, and installation requirements. By understanding these distinctions, companies can make more informed and rational decisions when selecting valves, ensuring reliable and cost-effective operation over time.
Automatic Pressure Relief: When the temperature in the valve body rises, the valve seat automatically relieves pressure, eliminating the need for an external safety valve. This ensures the safety of transporting liquid media.
Fire Safety Design: Meets API607 and API6FA standards, ensuring the valve can function normally during fires or other emergency conditions.
Reliable Stem Sealing & Low Torque Operation: Dual sealing design, combined with graphite packing and lubricating grease, ensures reliable sealing of the stem in extreme temperature conditions. Sliding bearings and thrust bearings make valve operation easier.
Versatile Actuation Options: Fixed ball valves can be actuated manually, pneumatically, or electrically, offering flexibility for automation, which enhances operational efficiency.
Simple Structure: Floating ball valves only have an upper valve stem, and the ball core can move along the flow direction. Due to the ball's free movement, it can adjust the sealing state according to the medium pressure, making it ideal for small-diameter and low-pressure pipelines.
Application Range: Floating ball valves are mainly suitable for low-pressure, small-diameter pipelines. When the medium pressure is too high, it may cause the ball to damage the outlet valve seat, increasing valve operating torque.
Fixed Ball Valve: The ball core is fixed by upper and lower valve stems and does not move along the flow direction. Sealing depends on the movement of the valve seat to pressurize the ball.
Fixed Ball Valve: Ideal for high-pressure, large-diameter pipelines. The design of fixed ball valves helps reduce valve seat sealing pressure, which lowers operating torque, making them more suitable for demanding environments.
Fixed Ball Valve: Capable of achieving unidirectional and bidirectional sealing, as well as middle cavity pressure relief, making it ideal for high-pressure, high-flow, and complex working conditions.
A: Fixed ball valves are better suited for high-pressure, large-diameter applications due to their sealing structure, which helps reduce valve seat pressure and increases pressure resistance.
Q2: Can fixed ball valves be used in low-pressure, small-diameter pipelines?
A: Although floating ball valves perform better in low-pressure, small-diameter pipelines, fixed ball valves can still be used, albeit at a higher cost.
Q3: How can leakage issues in ball valves be addressed?
A: First, check for seal damage or packing failure. If structural issues are present, replace the damaged components. Regular inspection and maintenance can help prevent leakage issues.
For more detailed valve selection guidance and technical support, feel free to contact DVS. We are here to provide you with one-on-one professional assistance.
This article compares the structural features of floating ball valves and fixed ball valves, analyzing their differences in sealing methods, applicable working conditions, and installation requirements. By understanding these distinctions, companies can make more informed and rational decisions when selecting valves, ensuring reliable and cost-effective operation over time.
1. Structural Features of Fixed Ball Valves
Fixed ball valves typically use flanged or butt-welded connections and are widely used in the control of fluids such as water, steam, oils, liquefied gases, and natural gas. The key feature of a fixed ball valve is its fixed ball core, which is securely attached to the valve body via an upper and lower valve stem. Unlike floating ball valves, the ball in a fixed ball valve does not move under fluid pressure.Key Features of Fixed Ball Valves:
Double Block and Bleed Function: Uses spring-loaded floating seats that effectively block fluid flow when the valve is fully open or closed, ensuring leakage substances can be safely discharged through a bleed valve.Automatic Pressure Relief: When the temperature in the valve body rises, the valve seat automatically relieves pressure, eliminating the need for an external safety valve. This ensures the safety of transporting liquid media.
Fire Safety Design: Meets API607 and API6FA standards, ensuring the valve can function normally during fires or other emergency conditions.
Reliable Stem Sealing & Low Torque Operation: Dual sealing design, combined with graphite packing and lubricating grease, ensures reliable sealing of the stem in extreme temperature conditions. Sliding bearings and thrust bearings make valve operation easier.
Versatile Actuation Options: Fixed ball valves can be actuated manually, pneumatically, or electrically, offering flexibility for automation, which enhances operational efficiency.
2. Structural Features of Floating Ball Valves
Floating ball valves use two valve seat seals at the inlet and outlet to hold the ball core in place. The valve stem rotates to move the ball and control the flow. Unlike fixed ball valves, the ball in a floating ball valve moves toward the outlet under the pressure of the medium, which improves the sealing performance.Key Features of Floating Ball Valves:
Self-Adjusting Sealing: The ball core, when closed, is pushed by the medium pressure against the outlet valve seat, improving the sealing effect. Floating ball valves are particularly well-suited for low-pressure, small-diameter applications.Simple Structure: Floating ball valves only have an upper valve stem, and the ball core can move along the flow direction. Due to the ball's free movement, it can adjust the sealing state according to the medium pressure, making it ideal for small-diameter and low-pressure pipelines.
Application Range: Floating ball valves are mainly suitable for low-pressure, small-diameter pipelines. When the medium pressure is too high, it may cause the ball to damage the outlet valve seat, increasing valve operating torque.
3. Key Differences Between Floating and Fixed Ball Valves
(1) Sealing Structure:
Floating Ball Valve: The ball can float freely along the flow direction. The inlet and outlet valve seats create a seal with the medium pressure and preloading force.Fixed Ball Valve: The ball core is fixed by upper and lower valve stems and does not move along the flow direction. Sealing depends on the movement of the valve seat to pressurize the ball.
(2) Suitability for Different Working Conditions:
Floating Ball Valve: Best suited for low-pressure, small-diameter applications. Higher medium pressure may affect the ball's sealing performance and increase the operating torque.Fixed Ball Valve: Ideal for high-pressure, large-diameter pipelines. The design of fixed ball valves helps reduce valve seat sealing pressure, which lowers operating torque, making them more suitable for demanding environments.
(3) Valve Seat Sealing Capabilities:
Floating Ball Valve: Relies on the outlet valve seat to achieve forced sealing.Fixed Ball Valve: Capable of achieving unidirectional and bidirectional sealing, as well as middle cavity pressure relief, making it ideal for high-pressure, high-flow, and complex working conditions.
4. Common Questions and Answers (FAQ)
Q1: Which is more suitable for high-pressure applications, floating or fixed ball valves?A: Fixed ball valves are better suited for high-pressure, large-diameter applications due to their sealing structure, which helps reduce valve seat pressure and increases pressure resistance.
Q2: Can fixed ball valves be used in low-pressure, small-diameter pipelines?
A: Although floating ball valves perform better in low-pressure, small-diameter pipelines, fixed ball valves can still be used, albeit at a higher cost.
Q3: How can leakage issues in ball valves be addressed?
A: First, check for seal damage or packing failure. If structural issues are present, replace the damaged components. Regular inspection and maintenance can help prevent leakage issues.
Conclusion
Selecting the right ball valve for your pipeline system involves considering multiple factors, including working conditions, pressure requirements, and the nature of the fluid. Both floating ball valves and fixed ball valves have their ideal application scenarios. By understanding their structural characteristics and operating conditions, businesses can make more informed decisions, reduce equipment failures, and ensure the safe and stable operation of their pipeline systems.For more detailed valve selection guidance and technical support, feel free to contact DVS. We are here to provide you with one-on-one professional assistance.
