Zhejiang Dongri Valve Co., Ltd.
Trunnion-mounted ball Valves are often the preferred choice for demanding oil and gas, chemical, water treatment, and power-generation applications because they deliver three essential advantages. First, their fixed ball and trunnion supports minimize movement, operating torque, seat wear, and leakage, making them highly reliable in high-pressure and high-temperature service. Second, spring-loaded seats and double block and bleed designs provide dependable bidirectional sealing, pressure isolation, and safer maintenance. Third, their durable construction, fast 90-degree shutoff, lower actuator requirements, and availability in welded, split-body, and top-entry designs support long-term operating efficiency. To achieve these benefits, proper installation, alignment, leak testing, lubrication, inspection, and timely replacement of worn seats or seals are essential, while compliance with API 6D and ISO 14313 helps ensure consistent quality and safety.
Choosing between a floating ball valve and a trunnion-mounted ball valve can affect operating torque, maintenance work, sealing performance, and the total cost of a piping system. I have seen buyers focus only on line size or pressure rating, then discover that actuator sizing, seat wear, or service conditions were not considered.
The right choice depends on how the valve works in the actual system.
A floating ball valve has a ball that is not fixed to a stem at the bottom. The ball can move slightly inside the body. When line pressure rises, the ball moves toward the downstream seat and helps create a seal.
This design is often used for small and medium line sizes. It has a simpler structure and may be easier to maintain. The valve can work well in water, air, gas, and many general process applications when the pressure, temperature, and media match the manufacturer’s specifications.
A trunnion-mounted ball valve uses a fixed ball. The ball is supported by a lower stem or trunnion and an upper stem. The seats move toward the ball to maintain contact.
The fixed support reduces the load transferred to the valve seats. That feature becomes useful as valve size and pressure increase. A large floating ball may push strongly against the downstream seat, while a trunnion design can manage the ball load through its support system.
I do not treat one design as suitable for every pipeline. A 2-inch utility line and a 24-inch gas pipeline face very different mechanical demands.
Floating ball valves can require more operating torque as pressure and size rise. The ball presses against the seat, and that contact creates friction. An actuator must provide enough torque to open and close the valve under the expected pressure conditions.
Trunnion ball valves often reduce the operating torque created by ball movement. This can allow a smaller actuator for a similar service, though the final actuator size still depends on pressure, temperature, seat material, differential pressure, and safety requirements.
A project example helps explain the difference.
I once reviewed a valve selection for a large natural gas line. The team initially compared only the purchase prices of two valve types. After checking the operating torque and actuator requirements, the trunnion-mounted option offered a more practical package for the larger line. The valve body cost was not the only factor. The actuator, support structure, installation space, and maintenance plan also affected the decision.
For a smaller water line, a floating valve may provide a suitable balance between price, size, and service needs. For a high-pressure line with a large diameter, a trunnion design may reduce the mechanical load placed on the seats and actuator.
The torque value should come from the valve supplier’s data, not from a general rule.
People often ask, “Which valve seals better?” That question is too broad.
Both floating and trunnion ball valves can provide reliable shutoff when they are correctly selected, installed, and operated. Sealing performance depends on seat material, pressure direction, temperature, media, surface finish, cavity pressure, and maintenance practice.
Floating valves use line pressure to help press the ball against the downstream seat. This can support shutoff in many standard applications. The same contact force may increase seat wear when the valve operates frequently or handles abrasive particles.
Trunnion valves usually use spring-loaded seats. The seats stay in contact with the ball at low pressure, while line pressure can add force when needed. Some designs include self-relieving or pressure-relieving features. These details vary by product and should be checked in the valve documentation.
For a clean gas service with limited cycling, either design may work well when the pressure class and temperature range are suitable. For slurry, dirty fluid, or media with solid particles, I pay closer attention to seat construction, flushing options, cavity design, and the supplier’s service record. A valve label alone cannot answer those questions.
I use this checklist before recommending a valve:
Record the line size and pressure class
Larger sizes and higher pressures often make trunnion support more attractive.
Check the pressure differential
The pressure at opening and closing can change the required torque.
Review the media
Clean liquid, gas, corrosive fluid, and abrasive slurry place different demands on seats and body materials.
Estimate the operating cycle
A valve used twice a year has a different duty from one that cycles every few minutes.
Size the actuator from verified torque data
Include breakaway torque, running torque, emergency conditions, and the required safety margin set by the project.
Confirm maintenance access
A valve that fits the pipe but cannot be serviced safely may create trouble later.
Check the required shutoff and testing conditions
Ask for the applicable test standard, seat leakage class, fire-safe option, and pressure-relief details when the service requires them.
My view is simple: floating ball valves often suit compact, general-purpose systems, while trunnion-mounted ball valves often suit larger or higher-pressure applications. That is a guide, not a substitute for engineering data.
The common mistake is choosing by valve name alone. A sound decision compares pressure, size, media, cycling, torque, actuator cost, seat design, and maintenance access as one package. When those factors match the service, both valve types can perform well.
When I choose a valve for a piping system, I look beyond the purchase price. The valve must control flow, seal well, handle the working pressure, and remain practical to service. A poor match can lead to leakage, pressure loss, extra maintenance, or an early replacement.
That is why floating ball valves may be a suitable option for many water, oil, gas, and general industrial applications. Their design is simple, their operation is quick, and their cost is often manageable for systems that do not need a more complex valve structure.
How a floating ball valve works
A floating ball valve uses a hollow ball with a passage through its center. The ball sits between two valve seats and is not fixed to a stem at the lower side. When the stem turns the ball, the opening lines up with the pipe to allow flow. A quarter turn moves the valve to the closed position.
When the valve closes, pressure from the upstream fluid pushes the ball against the downstream seat. This pressure-assisted action helps the seat create a tight shutoff.
The design contains fewer main parts than many other valve types. That can make inspection and replacement easier, especially in systems where the valve size and pressure rating remain within the design range.
Why I may select a floating ball valve
A floating ball valve usually moves from open to closed with a 90-degree turn. This suits applications that need fast isolation, such as equipment maintenance, tank connections, pump lines, and utility piping.
A lever handle also gives me a simple visual indication. The handle position normally shows whether the valve is open or closed.
The ball presses against the valve seat when line pressure is present. With the correct seat material and pressure rating, this arrangement can provide a tight seal for clean liquids, air, natural gas, and other compatible media.
The result depends on the full valve selection. Fluid temperature, pressure, chemical content, and particle level all affect sealing performance.
When the ball opening matches the pipe passage, the valve can offer a fairly direct flow path. This helps reduce pressure loss compared with some valves that place an obstruction in the flow path.
A full-port design is often considered when the system needs easier pigging, lower pressure drop, or a passage close to the pipe’s internal diameter. A reduced-port design may suit systems where compact size and lower cost have more value.
The quarter-turn mechanism is easy for operators to understand. Manual versions do not require a handwheel with many rotations, and automated versions can work with electric or pneumatic actuators.
If a seat or seal needs replacement, the valve may be easier to service than a design with a larger number of internal moving parts. The actual maintenance method depends on whether the valve is one-piece, two-piece, or three-piece.
Floating ball valves are commonly used in small and medium pipeline sizes. They can be found in water systems, compressed air lines, fuel service, process equipment, and building services.
For larger diameters or higher pressure loads, a trunnion-mounted ball valve may be more suitable because its ball has additional mechanical support. A floating design should not be selected only because it looks similar to another ball valve.
A practical selection example
Suppose I am choosing a valve for a water-treatment skid. The line carries clean water at a moderate temperature, the valve is used for isolation, and the operator needs a compact manual handle.
A floating ball valve may fit this duty when:
A different choice may be better for wastewater containing large solids, high-temperature steam, abrasive slurry, or a line that needs regular flow adjustment. Ball valves are generally better suited to open-or-closed service than continuous throttling. Keeping the valve partly open for long periods can wear the seats and disturb the flow path.
What I check before ordering
I use a short checklist:
I also check the product documents rather than relying on a general description. The pressure rating may change with temperature, and a valve suitable for water may not be suitable for a chemical or gas service.
Floating ball valves can be a sensible choice when the system needs compact isolation, quick operation, and a direct flow path. Their value comes from matching the valve to the service, not from using the same design everywhere.
When I compare options, I focus on the actual working conditions. A simple valve in the right application can support stable operation and easier maintenance. A simple valve in the wrong application can create leaks, wear, and added work.
When I select a ball valve, I look at more than pressure class and pipe size. The valve must match the operating cycle, fluid, temperature, space limits, and maintenance plan. That is why a floating ball valve can be a practical choice over a trunnion-mounted design in many small and medium pipeline applications.
A floating ball valve does not use a fixed lower and upper stem support to hold the ball in place. The ball moves slightly under line pressure. This movement pushes the ball against the downstream seat and helps create a tight shutoff.
Here are three reasons I may choose a floating design.
A floating valve has a simpler internal structure. It usually contains fewer support parts, bearings, and load-carrying components than a trunnion-mounted valve.
That simpler design can reduce:
For a water treatment line, compressed air system, or general process pipe with a moderate diameter, the extra structure of a trunnion valve may not provide enough value to justify the added cost.
I often see this choice in utility systems where the valve opens and closes during planned operations rather than cycling every few minutes. The system still needs dependable isolation, but it may not need the load support used in larger high-pressure pipelines.
The total project cost also includes transport, lifting, flange alignment, actuator sizing, and future service. A lighter floating valve can make these tasks easier, especially in areas with limited access.
A floating ball valve uses line pressure to help press the ball against the downstream seat. When the valve is closed, this contact can support a tight seal when the valve is correctly selected for the medium and operating conditions.
This design works well in applications such as:
The sealing result depends on more than the valve body. I also check the seat material, pressure rating, temperature range, fluid cleanliness, and installation quality.
For example, a plant may use a floating ball valve on a clean-water branch line that operates at a stable pressure. The valve may remain open for long periods and close during maintenance isolation. In that situation, the pressure-assisted seal can meet the operating need without the larger support system found in a trunnion valve.
A floating design is not a solution for every fluid. Abrasive particles, heavy solids, high temperature, or repeated pressure changes can affect seat life. The valve specification should match the actual medium instead of relying on the valve type alone.
Floating ball valves often have a compact body and a straightforward operating mechanism. This can help when the pipeline is installed in a narrow plant area or when the valve must fit between existing equipment.
The smaller structure may also reduce actuator size. Lower operating torque can make the complete valve package easier to install, though the actual torque still depends on pressure, seat material, fluid, temperature, and cycle frequency.
Maintenance teams may also prefer the simpler construction. Inspection and part replacement can be more direct when the valve does not include extra trunnion supports and related components.
A common maintenance example is a utility line installed above a service platform. The team may have limited room for lifting equipment and only short access windows during planned shutdowns. A compact floating ball valve can make removal and replacement more manageable.
Good maintenance still requires proper procedures. The line must be isolated and depressurized before service. Seat and seal materials should be checked against the fluid. The actuator should be tested after installation, and the valve should be operated within its rated conditions.
A floating valve may not be the right fit for large-diameter or high-pressure service. As valve size and pressure increase, the ball load can rise. This may increase operating torque and place more force on the seats and stem.
A trunnion-mounted ball valve supports the ball with fixed shafts or trunnions. The ball carries less side load from the line pressure, which can make this design suitable for:
The selection should follow the operating data. I usually compare valve size, pressure class, temperature, medium, expected cycles, actuator torque, maintenance access, and failure requirements before making a recommendation.
I use a simple review process:
Floating ball valves can offer a useful balance of cost, size, shutoff performance, and service simplicity for many moderate-duty systems. Trunnion valves have their own strengths in larger, higher-pressure, or frequently operated applications.
The best choice is not based on the valve name alone. It comes from matching the valve structure to the pipeline conditions, operating pattern, and maintenance plan.
Choosing between a floating ball valve and a trunnion-mounted ball valve can affect cost, operation, maintenance, and service life. I often see buyers focus only on line size or pressure class. That approach can lead to a valve that works on paper but creates high operating torque or extra maintenance in the field.
The better choice starts with the service conditions: pressure, temperature, media, valve size, operating frequency, and actuator capacity.
A floating ball valve has a ball that is held in place by the valve seats. When line pressure pushes the ball toward the downstream seat, the ball forms a tight seal.
This design is common in small and medium-sized pipelines. It has a simple structure, fewer internal parts, and a lower purchase cost in many applications.
I usually look at a floating valve when:
A floating ball valve can be a practical fit for water systems, air lines, general process service, and selected oil or gas applications. The final choice still depends on the manufacturer’s pressure and material data.
A trunnion-mounted ball valve uses a fixed lower and upper support to hold the ball. The ball does not move freely with the line pressure. The seats move toward the ball to create the seal.
This structure reduces the force placed on the ball seats. It can also lower operating torque in large or high-pressure valves, which helps when selecting an actuator.
I often consider a trunnion design when:
Trunnion-mounted valves often include a cavity relief design, double piston effect seats, emergency sealant injection points, or other features for specific process needs. These features can support maintenance planning, but they may also increase the valve’s cost and inspection requirements.
A floating ball valve can develop higher torque as pressure and valve size increase. Line pressure pushes the ball into the seat, which increases contact force.
A trunnion-mounted valve carries the ball on fixed supports. The seat movement is more controlled, so the operating torque can be lower for a similar pressure and size range.
This affects actuator selection. A small actuator may be suitable for one service but insufficient for another. I always ask for the valve torque data across the full operating range, not only the breakaway torque.
Floating ball valves are often selected for smaller pipeline sizes because their structure is simple and compact.
For larger pipelines, a trunnion-mounted design may offer better control of ball movement and seat loading. A large floating valve can still be suitable, but the supplier should confirm torque, seat stress, actuator sizing, and test results.
Pressure and temperature influence seat performance, body strength, and valve torque.
A floating design may work well at moderate pressure and temperature when the seat material matches the media. High pressure can increase the load on the downstream seat.
A trunnion-mounted design may be better suited to high-pressure service, especially when the valve is large or operated often. The design alone does not guarantee suitability. Body material, trim, seat material, fire-safe construction, and pressure testing all matter.
Floating ball valves have fewer internal components, which can make inspection and repair more straightforward.
Trunnion-mounted valves may include more parts, such as support bearings, springs, seat carriers, and injection fittings. These parts provide useful functions in demanding service but require a maintenance plan that matches the valve design.
I recommend checking:
A lower purchase price does not always mean lower ownership cost. A valve that is difficult to operate or repair may create more work for the plant team.
I use the following steps when comparing the two designs.
Prepare the line size, pressure class, operating pressure, temperature, media, flow direction, and valve connection standard.
The media description should be specific. “Gas” or “liquid” is not enough. Mention whether the service contains sand, particles, water, corrosive compounds, or abrasive solids.
A valve that works twice a year may have different needs from a valve that cycles every hour.
Check the expected number of cycles, fail position, control method, and available instrument air or electrical power. These details help determine the actuator and valve design.
Ask the supplier to provide:
Torque can change with pressure, temperature, seat material, and media. A single torque value may not show the full operating condition.
Seat materials such as PTFE, reinforced PTFE, PEEK, or metal options serve different conditions. The right choice depends on temperature, pressure, chemical compatibility, and expected wear.
Body and trim materials also need review when the media may cause corrosion. Material selection should follow the actual process data rather than a general product label.
Useful documents may include:
These records help the engineering and maintenance teams confirm that the valve matches the project requirements.
Consider a water transfer line with a moderate diameter, steady pressure, clean media, and occasional isolation. A floating ball valve may offer a simple and suitable solution when its pressure, temperature, and material limits match the line.
Now consider a high-pressure gas pipeline with a large diameter, frequent operation, and a powered actuator. A trunnion-mounted ball valve may provide better control of operating torque and seat loading.
Neither choice should be made from pipe size alone. A small valve may need a special seat or material because of the media. A large valve may still be unsuitable if the pressure, temperature, or actuator data has not been checked.
For many general isolation duties, a floating ball valve can meet the need with a simpler structure. For larger, higher-pressure, or frequently operated lines, a trunnion-mounted valve may be a better match.
I treat the decision as a service-fit question, not a design competition. The right valve is the one that matches the process data, actuator plan, maintenance ability, and project budget.
For any inquiries regarding the content of this article, please contact Wang Zhixiang: 241126365@qq.com/WhatsApp +8613777730323.
American Petroleum Institute, 2018, Pipeline Transportation Systems for Liquids and Slurries
International Organization for Standardization, 2015, Industrial Valves Testing of Valves Part 1 Pressure Tests Test Procedures and Acceptance Criteria
American Petroleum Institute, 2019, Fire Test for Valves
International Organization for Standardization, 2012, Industrial Valves End-to-End and Center-to-End Dimensions for Valves
American Society of Mechanical Engineers, 2022, Process Piping
Mannesmann Rexroth, 2020, Industrial Ball Valve Design and Maintenance Guide
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August 27, 2026
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