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In many industrial processes, valves are critical components that control the flow of liquids, gases, or slurries within a system. Among the many types available, the manual trunnion ball valve is widely appreciated for its durability, precision, and reliability in handling high-pressure and large-diameter applications. Choosing the right one for your operation is not just a matter of picking a product off the shelf—it requires a clear understanding of your operational needs, technical specifications, and long-term maintenance considerations.
This article offers an in-depth, easy-to-understand guide to help you make the right decision when selecting a manual trunnion ball valve. We will cover how these valves work, their unique advantages, the factors that influence your choice, and how to match their capabilities with your specific application.
A manual trunnion ball valve is a type of quarter-turn valve that uses a fixed, anchored ball design supported at both the top and bottom by trunnions (or shafts). The ball inside the valve contains a bore through which the medium flows. Rotating the handle 90 degrees opens or closes the valve.
Unlike floating ball valves—where the ball is held in place only by the compression of the seats—the trunnion ball valve’s anchored ball design helps reduce the operating torque and minimizes wear on the seats, especially under high-pressure conditions. The “manual” aspect means that the operator turns a hand lever or gear operator to control the valve’s position, making it simple and straightforward to operate without requiring external power sources.
Manual trunnion ball valves are widely used in oil and gas, petrochemical, power generation, water treatment, and other heavy-duty industries because they combine high performance with mechanical simplicity.
Some key advantages include:
High Pressure and Large Size Capability
Trunnion ball valves handle large-diameter pipelines and high-pressure applications more efficiently than floating ball valves. Their anchored ball design ensures stable operation even under intense conditions.
Reduced Operating Torque
Since the ball is fixed and supported by trunnions, less force is required to turn it, making operation easier for manual use.
Long Service Life
The design minimizes wear on the seats and seals, leading to a longer operational life and fewer maintenance interventions.
Tight Shut-off
These valves are known for providing excellent sealing performance, preventing leakage even under demanding operating conditions.
The choice of a manual trunnion ball valve should not be rushed. Each detail—ranging from material selection to operational environment—can impact the valve’s performance and lifespan. Here are the most important considerations:
The size of the valve must match the pipeline diameter, and the pressure rating should align with the maximum operating pressure of the system. Manual trunnion ball valves are available in a range of pressure classes (such as ANSI Class 150, 300, 600, or higher) and sizes from a few inches to several feet in diameter.
Tip: For high-pressure applications, consider a valve with reinforced trunnions and seats designed to withstand the full system pressure without deformation.
The valve body, ball, and seats should be made from materials suitable for your fluid type and environmental conditions. Common body materials include:
Carbon steel for general industrial use with non-corrosive fluids.
Stainless steel for corrosive environments or hygienic applications.
Duplex or super duplex stainless steel for seawater or highly aggressive chemicals.
Seat and seal materials (such as PTFE, reinforced PTFE, or metal seats) should also be chosen based on temperature, pressure, and media compatibility.
The way the valve connects to the pipeline is critical for sealing reliability and ease of installation. Common connection types include:
Flanged ends for large, high-pressure pipelines and easy maintenance access.
Welded ends for permanent installations with no risk of leakage at the connection points.
Threaded ends for smaller pipelines and lower pressure applications.
Take into account the temperature, pressure, and flow characteristics of the medium. Extreme cold, high heat, or abrasive fluids will require special materials or coatings to prevent damage.
For example:
Cryogenic applications require valves with extended bonnets and low-temperature-tolerant materials.
High-temperature environments may need metal-seated valves instead of soft-seated designs.
Trunnion ball valves can use either soft seats (made of polymeric materials) or metal seats:
Soft seats provide tight shut-off and are suitable for clean fluids and moderate temperatures.
Metal seats resist high temperatures, abrasive particles, and corrosive chemicals but may allow a small amount of leakage.
Valves that allow easy access to internal components without removing them from the pipeline can save significant downtime during maintenance. Look for designs with replaceable seats and seals, as well as corrosion-resistant coatings on critical components.
Even though you are selecting a manual valve, it’s worth considering how it could be adapted for automation in the future. Many trunnion ball valves can be retrofitted with pneumatic or electric actuators if operational needs change.
Check that the valve meets recognized international standards, such as API 6D, ASME B16.34, ISO, or CE marks. Compliance ensures that the valve has been manufactured to strict safety, quality, and performance criteria.
Understanding where these valves excel can help confirm whether they are the right choice for your project:
Oil and Gas Pipelines: Their high-pressure capability and large size options make them ideal for controlling crude oil, natural gas, and refined petroleum products.
Petrochemical Plants: They handle aggressive chemicals and high-temperature processes while maintaining leak-tight sealing.
Power Generation: Cooling systems, steam lines, and fuel gas controls often rely on trunnion ball valves for reliability under demanding loads.
Water Treatment: Used in desalination plants, wastewater facilities, and potable water systems due to their durability and sealing performance.
Even experienced engineers can overlook details that affect valve performance. Some common mistakes include:
Underspecifying Materials
Choosing a cheaper material that cannot withstand the process fluid will lead to premature failure.
Ignoring Future Needs
Failing to consider potential system expansions or automation upgrades can result in costly replacements later.
Overlooking Maintenance Accessibility
If the valve is installed in a difficult-to-reach location without service-friendly features, maintenance costs will rise.
Gather Complete System Data
Include pressure, temperature, flow rate, medium type, and any special environmental conditions.
Consult Valve Experts
Engage with manufacturers or suppliers early in the process to match the valve design with your operational requirements.
Review Life-Cycle Costs
Consider not only the purchase price but also installation, maintenance, and replacement costs over the valve’s lifespan.
Inspect Quality Control Procedures
Choose valves from manufacturers with rigorous testing protocols and documented quality assurance systems.
Selecting the right manual trunnion ball valve for your operation is a process that requires careful consideration of technical requirements, environmental factors, and long-term performance expectations. By understanding the unique benefits of trunnion ball valve design, you can match the valve’s capabilities to your specific needs—ensuring reliable operation, reduced downtime, and optimal flow control.
From the material of the body and seats to the connection type and pressure rating, every detail matters. A well-chosen manual trunnion ball valve will not only perform effectively under current conditions but also adapt to future operational changes, making it a sound long-term investment.
For industries seeking dependable flow control solutions, high-quality manual trunnion ball valves from reputable suppliers are essential. Goole Valve Technology Co., Ltd. has established itself as a trusted provider of precision-engineered valves that meet stringent international standards, delivering performance and reliability across a wide range of industrial applications.
