Zhejiang Dongri Valve Co., Ltd.
Choosing between floating and trunnion-mounted ball Valves depends on your pressure rating, Valve size, and operating conditions. Floating ball valves provide a simple, economical solution for low- to medium-pressure applications, while trunnion-mounted designs deliver greater stability, reduced operating torque, and dependable performance in high-pressure or large-diameter systems. With the right selection, you can improve efficiency, safety, and long-term reliability. We help you solve your pressure puzzle by matching your application with the ideal Ball Valve solution.
Choosing between a floating ball valve and a trunnion ball valve can affect operating torque, shutoff performance, maintenance work, and the total cost of a piping system.
I have seen valve selections go wrong because the decision was based only on line size or purchase price. A valve may fit the pipe and still be a poor match for pressure, temperature, flow direction, or actuator size.
The better question is simple:
How will the valve work in the actual system?
A floating ball valve uses a ball that is not fixed to a lower stem or trunnion. The ball moves slightly under line pressure and presses against the downstream seat.
This design is common in:
The design has fewer main support parts, so the valve is often compact and easier to purchase at a lower initial cost. The operating torque may also be reasonable in smaller sizes.
The sealing action depends on line pressure pushing the ball against the seat. That can provide a strong shutoff when the valve has been selected correctly.
A floating valve may be a practical choice when:
A floating ball valve is not automatically a low-pressure valve. Some models are designed for demanding service. I always check the pressure class, temperature range, seat material, and tested shutoff rating instead of judging the valve by its name alone.
A trunnion ball valve uses a fixed ball supported by a trunnion, or mounted support shaft. The ball does not move freely toward the downstream seat in the same way as a floating ball.
The seats move toward the ball to maintain contact. This arrangement can reduce the force needed to turn the ball, especially in larger valves and higher-pressure systems.
Trunnion designs are often used in:
Because the ball is supported, the valve can handle high operating loads with less dependence on line pressure to move the ball into the seat. Many trunnion valves also include features such as:
These features are not present on every model. I treat them as design options that must be confirmed through the technical data sheet.
This point helps me explain the two designs to a project team.
With a floating ball valve, line pressure helps push the ball toward the seat. The sealing force is closely related to the pressure acting on the ball.
With a trunnion ball valve, the ball remains supported while the seats move toward it. The valve does not rely on the ball shifting through the line in the same way.
That difference affects several practical factors:
| Selection factor | Floating ball valve | Trunnion ball valve |
|---|---|---|
| Ball support | Ball is free to move slightly | Ball is fixed by a trunnion |
| Common size range | Small to medium applications | Medium to large applications |
| Operating torque | Can rise with size and pressure | Often more controlled in large sizes |
| Initial cost | Often lower | Often higher |
| Actuation | Suitable for many basic duties | Useful for larger or frequent operations |
| Maintenance features | Usually simpler | May include more service features |
| Typical use | General process and utility lines | High-pressure and pipeline service |
This table is a starting point, not a replacement for valve sizing.
I would look at a floating design when the system has moderate pipe sizes and the valve will not be cycled continuously.
For example, a water treatment plant may use a floating ball valve on a clean water branch line. The valve may open during normal operation and close during maintenance. If the pressure, temperature, seat material, and actuator torque all match the service, a trunnion design may add cost without providing a useful benefit.
A compressed air line in a factory can be another suitable case. The line may need reliable isolation, but it may not require a large actuator or special pipeline features. A compact floating valve can make installation easier.
The media still matters. Solids, scale, polymer buildup, and sticky materials can affect the seats and ball. A valve that works well with clean water may not work in the same way with slurry or contaminated fluid.
I usually study a trunnion design when the valve is large, the pressure is high, or the actuator must operate the valve often.
Consider a long natural gas pipeline. A large valve may need a powerful actuator, remote operation, and reliable sealing after many operating cycles. The supported ball can help control the operating torque. Features such as cavity relief, fire testing, and double block and bleed may also be part of the pipeline specification.
Another example is a high-pressure process unit where the valve sits in a critical isolation point. The project may require a documented seat test, a defined leakage rate, emergency sealant injection, or a double isolation arrangement. A trunnion valve may suit that specification, but only when the selected model includes the required features.
A trunnion valve is not a universal upgrade. Its extra features can increase purchase price, weight, installation effort, and maintenance requirements. If the process does not need them, the design may be more than the system requires.
I use a short review process before recommending a valve.
Record the nominal pipe size, design pressure, operating pressure, temperature, and pressure class.
Do not select a valve from the pipe diameter alone. Two 8-inch lines may have very different requirements because one handles water at a moderate pressure while the other handles high-pressure gas.
Write down the fluid and its condition.
Ask:
Seat and body materials must match the media. A strong valve body cannot compensate for an unsuitable seat material.
A valve that opens twice a year has a different duty from a valve that cycles every hour.
Frequent cycling increases the need to review:
A trunnion valve may be helpful for larger, frequently operated valves, but the final choice should come from a proper torque calculation.
I never rely on a general rule such as “large valve equals large actuator.”
The required torque can change with:
The supplier should provide breakaway, running, and closing torque data for the selected conditions. The actuator should be matched to those figures.
Some systems need more than simple on-off control.
Check whether the specification calls for:
These requirements can guide the design choice more than the valve type alone.
One mistake is choosing the cheapest valve without checking the full operating range. The valve may pass a basic inspection and still require a larger actuator after installation.
Another mistake is assuming that a trunnion valve will always seal better. Shutoff depends on seat materials, pressure, temperature, manufacturing quality, installation, and media condition. The support design matters, but it is only one part of the result.
I also see users compare face-to-face dimensions without checking the end connection. Flanged, threaded, welded, and wafer-style connections can affect installation and replacement work.
A further issue is ignoring access space. A large trunnion valve with an actuator, gearbox, bypass, or injection fittings may need more room than expected. Maintenance teams should be able to reach the stem, packing area, drain, and bleed connections.
A floating ball valve may be a suitable starting point when the application has:
A trunnion ball valve may deserve closer review when the application has:
The final selection should come from the complete service data, not from a simple rule based on valve type.
When I help a customer compare these designs, I ask for the line size, pressure, temperature, media, operating frequency, end connection, actuator requirement, and required standards. Those details usually show whether the project needs a simpler floating valve or the added support and features of a trunnion valve.
The right fit is the valve that performs within its stated range, matches the system’s risks, and remains practical to operate and maintain.
When I select a ball valve for a pressure system, I do not look only at the pipe size or the purchase price. I look at how the valve will handle pressure, how often it will operate, and what may happen if the line pressure changes.
Floating and trunnion-mounted ball valves can both provide reliable shutoff, but they work in different ways. The right choice depends on valve size, pressure rating, operating frequency, torque demand, and maintenance needs.
A floating ball valve has a ball that is not fixed to a stem support at the bottom. The stem turns the ball, while line pressure pushes the ball toward the downstream seat.
That movement helps the ball press against the seat and create a tight seal. The design has fewer internal parts, which can make it easier to inspect and maintain.
I often consider a floating ball valve for:
The design can work well when the pressure load is within the valve’s rated range. As the valve size and pressure increase, the force acting on the ball also rises. The actuator may need more torque to turn the ball, and seat wear may become a greater concern.
A floating ball valve may be a practical option when the system needs dependable on-off service without a large actuator or complex support structure.
A trunnion-mounted ball valve uses a fixed shaft arrangement. The ball is supported at the top and bottom, so it does not move freely with the line pressure.
The seats move toward the ball to maintain contact. Springs or other seat-loading parts help keep the sealing force stable when pressure changes.
This design is often selected for:
Because the ball is supported, the line pressure creates less turning resistance at the stem. The actuator can often be smaller than one used for a similar floating valve, although the total valve assembly may be larger and more costly.
A trunnion valve can also support features such as double block and bleed, cavity pressure relief, and emergency sealing options, depending on the design and specification.
This distinction causes many selection mistakes.
Most floating and trunnion ball valves are designed for isolation. They are intended to be fully open or fully closed. They are not automatically suitable for continuous throttling.
If I partially close a standard ball valve and leave it in that position, the high-velocity flow may damage the seats or ball. Pressure drop, cavitation, vibration, and noise can also affect the system.
For continuous pressure control, I may need a control valve, a characterized ball valve, or a special trim designed for throttling. The selection should include:
A shutdown ball valve and a pressure control valve may look similar from the outside, but their internal designs and operating duties can be very different.
Floating ball valves are commonly used in smaller or moderate-size lines. The ball relies on downstream movement to seal, so the force increases as pressure and diameter increase.
Trunnion-mounted valves support the ball mechanically. This makes them more suitable for larger bore sizes and higher-pressure services.
The exact limit depends on the manufacturer’s design, pressure class, material, and testing requirements. I always check the technical data instead of choosing by appearance.
Floating valves may require higher torque as line pressure rises because the ball presses against the downstream seat.
Trunnion valves often require lower operating torque because the ball is supported and the seats move toward it. This can reduce actuator size and support repeated operation.
Torque still depends on temperature, fluid type, seat material, pressure differential, and valve condition. A simple torque estimate may not be enough for a gas pipeline or high-cycle application.
A floating valve uses line pressure to help push the ball into the downstream seat. This can provide effective sealing in the right service.
A trunnion valve uses spring-loaded seats and may offer sealing at lower pressure conditions. It can also provide more control over cavity pressure and seat behavior.
Both designs require correct material selection. A soft seat may work for clean fluids at moderate temperatures, while metal seats may be considered for higher temperatures, abrasive particles, or fire-safe service.
Floating ball valves have a relatively simple internal structure. This may make them easier to repair in smaller process systems.
Trunnion valves contain more parts, including trunnions, springs, and movable seats. Maintenance may require more planning, special tools, and trained personnel.
For a remote pipeline, I also consider the availability of replacement seats, seals, actuators, and service support.
A floating valve often has a lower initial cost for suitable small and medium applications. A trunnion valve may cost more because of its support structure and seat system.
Purchase price should not be the only factor. A valve that needs a large actuator, frequent seat replacement, or difficult field maintenance may cost more over its service life.
I use a step-by-step review before choosing between the two designs.
Ask whether the valve will isolate flow, control pressure, prevent reverse flow, or support emergency shutdown.
If the valve will remain partly open during normal operation, a standard isolation ball valve may not be suitable.
Collect the normal and maximum values for:
A valve suitable for clean water may not suit wet natural gas, slurry, or a chemical stream.
The pressure difference across the valve affects torque, seat loading, and actuator sizing.
A valve that opens easily during low differential pressure may need much more force during high differential pressure. I ask the supplier for torque data across the operating range rather than checking only one point.
A floating valve may fit a compact process skid with moderate pressure and limited cycling.
A trunnion-mounted valve may fit a large gas pipeline where the valve must handle high pressure, large diameter, and frequent automated operation.
The project specification may require standards for pressure testing, fire-safe performance, fugitive emissions, materials, or pipeline service.
I check the required standards with the engineering team and valve supplier before ordering. A correct body style does not replace the need for proper testing and documentation.
The actuator must match the required torque, failure position, cycle time, and control signal.
For a gas isolation system, the project may also require a shutdown function, position feedback, or a manual override. These details affect the complete valve package.
Suppose I am reviewing a valve for a water treatment skid. The line is moderate in size, the pressure is stable, and the valve opens only during maintenance or process changeover. A floating ball valve may meet the need if the materials, pressure rating, and seat design match the water quality.
Now consider a large gas transmission line. The valve may need remote actuation, repeated operation, low operating torque, and reliable sealing during pressure changes. A trunnion-mounted ball valve may be a better fit for that duty.
Neither choice is automatic. I still review the pressure class, temperature range, gas composition, actuator torque, seal materials, and required tests.
Some buyers choose a floating valve because it is less expensive, then discover that the actuator cannot handle the actual operating torque.
Others select a trunnion valve for a small, low-pressure line where its added features provide little value.
Another frequent issue is using an isolation valve for throttling. If pressure control is part of the process, the valve should be selected around flow behavior and control range, not only shutoff performance.
The useful question is not “Which valve is better?” I ask, “Which design matches the pressure, size, movement, fluid, and service duty of this system?”
Floating ball valves can provide a simple solution for many moderate applications. Trunnion-mounted ball valves can support larger, higher-pressure, and more demanding systems. Careful review of operating conditions helps prevent actuator problems, seat damage, and avoidable maintenance work.
When I choose a ball valve, pressure is only one part of the decision. A valve may show a high pressure rating on paper, yet the rating can change with temperature, valve size, body material, and the fluid being handled.
I start with the actual operating conditions:
This information helps me compare valves based on service needs rather than a single pressure number.
Ball valves are commonly marked with ratings such as Class 150, Class 300, PN16, or PN40. These markings describe pressure limits under defined conditions. They do not mean the valve can handle the same pressure at every temperature.
For example, a valve rated for 1000 psi at room temperature may have a lower allowable pressure at a higher temperature. I always check the pressure-temperature chart supplied by the manufacturer.
The rating should also match the weakest part of the assembly. A valve may be rated for high pressure while the connected pipe, fitting, flange, or gasket has a lower limit. The complete system must be checked as one unit.
A floating ball valve uses line pressure to press the ball against the seat. This design can provide reliable shutoff in water lines, air systems, fuel service, and many process applications.
I often consider a floating ball valve when:
A smaller floating valve can work well in a compressed air line or water system. The seat material still matters. PTFE seats suit many clean fluids, while other seat materials may be needed for higher temperature or tougher service.
A trunnion-mounted ball valve supports the ball with fixed stems or support points. The ball does not move as freely as the ball in a floating design. This reduces the operating force, which can help with large pipe sizes and higher pressure systems.
I look at this design when:
For a pipeline carrying gas or liquid over a long distance, a trunnion-mounted valve may be a better fit than a floating design. The final choice still depends on pressure class, temperature, body material, seat design, and shutoff requirements.
A full-port ball valve has a bore close to the inside diameter of the pipe. It creates less flow restriction and can support pigging in some pipeline systems.
A reduced-port valve has a smaller opening through the ball. It may cost less and can be suitable where a small pressure drop is acceptable.
I do not choose a full-port valve only because it sounds stronger. Port size mainly affects flow, pressure loss, cleaning access, and equipment compatibility. The pressure rating comes from the valve construction and design, not simply from the bore size.
Common body materials include brass, stainless steel, carbon steel, and special alloys. The right material depends on pressure, temperature, corrosion risk, and fluid properties.
For clean water and moderate service, brass may be suitable in some systems. Stainless steel can be a better option where corrosion resistance or hygiene is required. Carbon steel is often used in industrial piping, but the fluid and external environment must be reviewed.
I also check the stem, ball, seats, seals, and end connections. A stainless steel body does not automatically make every internal part suitable for the application.
Imagine a water line operating at 12 bar with a maximum temperature of 60°C. The pipe size is DN50, and the valve will open and close several times each day.
I would compare:
A PN16 valve may appear suitable at a basic level, but the selection still depends on the manufacturer’s data and the system’s pressure changes. If water hammer is possible, I would also review closing speed and actuator settings.
A system can experience pressure spikes when a pump starts, a check valve closes, or a ball valve shuts too quickly. These short events may place more stress on the valve than the normal working pressure.
When I see frequent pressure changes, I review:
A valve selected only from the normal pressure may not provide enough margin for these events.
I use this simple order:
The most suitable ball valve is not always the one with the largest pressure number. It is the valve whose rating, materials, design, and operating method match the complete system. When I compare these points together, I reduce the chance of leakage, difficult operation, and early replacement.
When a pipeline shows pressure loss, unstable flow, or repeated valve damage, the problem may not come from the pump or compressor. The ball valve may be the wrong size, material, pressure class, or bore design.
I start by looking at the full operating picture, not just the pipe diameter. A valve that fits the line can still create trouble if its pressure rating does not match the system or if its seal cannot handle the media.
Every ball valve has a pressure rating. This rating should match the actual system pressure at the working temperature.
I check:
A valve rated for water at room temperature may have a lower allowable pressure at higher temperatures. The product data sheet should show the pressure-temperature limits. I do not rely on the pipe size alone when choosing a valve.
A pressure gauge can also reveal useful information. If the gauge before the valve shows much higher pressure than the gauge after it, the valve may be undersized, partly closed, or affected by debris.
The fluid inside the pipe affects the valve body, ball, stem, and seat.
Water, air, oil, steam, chemicals, and abrasive fluids place different demands on the valve. Stainless steel may suit some corrosive services, while carbon steel may be used in other systems. PTFE seats work well in many applications, but temperature and media compatibility still need checking.
I ask these questions before selecting a valve:
A valve that works well on clean water may not perform the same way in a slurry line. Solid particles can wear the seat and affect shutoff.
The bore controls how much flow can pass through the valve.
A full-port ball valve has a flow passage close to the inside diameter of the connected pipe. It usually creates less resistance when the valve is open. A reduced-port valve has a smaller passage and may create more pressure loss.
For a system that needs steady flow, I compare the valve bore with the required flow rate and pressure drop. Selecting a valve only by nominal pipe size can lead to poor results.
A typical maintenance case involves a 2-inch compressed-air line fitted with a reduced-port valve. The line size looked correct, yet tools at the end of the branch received unstable air pressure. After checking the flow path, the maintenance team found that the valve bore limited the available flow. A correctly sized full-port valve reduced the restriction. The final selection still needed to match the line pressure, thread or flange type, and seal material.
The valve connection must match the pipeline.
Common options include:
I check the standard, size, face-to-face dimension, gasket needs, and available installation space. A valve with the wrong connection may require adapters, which can add leak points and make future service harder.
A manual handle may suit a valve that is adjusted only during maintenance. An actuator may help when the valve must respond to a control signal or operate from a remote panel.
Pneumatic and electric actuators need correct torque and control settings. The actuator should not be selected from valve size alone. Seat friction, pressure difference, temperature, and cycle frequency all affect the required operating force.
For automatic systems, I also check whether the valve should be normally open or normally closed during a power or air failure. That choice should match the process risk and the site control plan.
A suitable ball valve can still perform poorly if it is installed under stress.
I keep the pipe properly supported and avoid forcing the valve into position. The flow direction, where marked, should be followed. The line should be cleaned before installation because welding debris, rust, and grit can damage the sealing surfaces.
After installation, I check for:
Testing should follow the site procedure and the valve maker’s instructions. Pressure testing with an unsuitable medium can create a safety risk, so the test method must fit the valve and the piping system.
I keep the valve decision easy to review. A short record can include:
This record helps maintenance teams replace the valve with a compatible model later. It also reduces the chance of choosing a product from a single detail, such as size or price.
Pressure problems rarely have one cause. The valve, pipe, pump, media, temperature, and operating method work as one system. I choose the ball valve after checking each part of that system. That approach helps control pressure loss, reduce leakage risk, and make maintenance more predictable.
We has extensive experience in Industry Field. Contact us for professional advice:Wang Zhixiang: 241126365@qq.com/WhatsApp +8613777730323.
American Petroleum Institute, 2022, API Specification 6D: Pipeline and Piping Valves
International Organization for Standardization, 2015, ISO 17292: Metal Ball Valves for Petroleum, Petrochemical and Allied Industries
American Society of Mechanical Engineers, 2022, ASME B16.34: Valves—Flanged, Threaded and Welding End
International Organization for Standardization, 2016, ISO 5208: Industrial Valves—Pressure Testing of Metallic Valves
American Petroleum Institute, 2019, API Standard 598: Valve Inspection and Testing
American Society of Mechanical Engineers, 2022, ASME B16.5: Pipe Flanges and Flanged Fittings
Metal hard sealing offers exceptional durability and dependable performance in demanding high-temperature environments. Designed to withstand temperatures of up to 500°C, it resists cracking, defo
Tired of frequent Valve failures an
Engineers trust Dongri API ball Valves
Dongri Ball Valves are engineered t
Email to this supplier
October 19, 2026
October 18, 2026
Privacy statement: Your privacy is very important to Us. Our company promises not to disclose your personal information to any external company with out your explicit permission.
Fill in more information so that we can get in touch with you faster
Privacy statement: Your privacy is very important to Us. Our company promises not to disclose your personal information to any external company with out your explicit permission.
