Trunnion vs. Floating Ball Valves: Key Differences and How to Choose

Choose a floating ball valve when the required size, pressure, and operating conditions suit a ball supported by its seats. Choose a trunnion-mounted ball valve when the ball needs mechanical support and lower operating torque is important, especially in larger or higher-pressure designs. The main difference is how the ball is supported and how sealing force is generated: a floating ball moves slightly toward the downstream seat under pressure, while a trunnion ball is held in place by upper and lower supports and the seats move toward it.

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Neither design is automatically better for every project. I recommend comparing the actual pressure and temperature envelope, size, media, operating frequency, actuator requirements, and maintenance plan before specifying either type.

Comparison Scope and Quick Difference Summary

Both valve types use a rotating ball with a bore to open or block flow, and both are commonly selected for on-off service. Their performance depends on the complete valve design, materials, seat construction, and applicable specifications—not only on whether the ball floats or is trunnion-mounted.

How the Designs Work

Floating Ball Design

A floating ball is not fixed by a lower support. The stem turns the ball, while the seats support it and provide the sealing interface. When the valve is closed, upstream pressure can push the ball downstream against its seat, helping create a seal.

This load path is simple, but it also means the seats and stem may experience greater forces as differential pressure increases. The resulting operating torque depends on factors such as pressure, seat material, valve size, and the condition of the components. Buyers should use the supplier’s torque figures for the specified operating conditions rather than assume a universal actuator size.

Trunnion-Mounted Ball Design

A trunnion valve supports the ball with a stem at the top and a trunnion or equivalent support at the bottom. The ball is restrained from moving downstream in the same way as a floating ball. Instead, the seats move toward the ball to provide sealing contact, with details varying by seat and valve design.

Because the ball is supported, the seats do not need to carry the same ball movement and load as in a floating design. This arrangement can help manage operating torque in larger or higher-pressure valves. Trunnion valves may also include features such as spring-loaded seats or cavity-relief provisions, but buyers should confirm the exact construction and functions in the datasheet.

Key Differences for Procurement and Specification

Pressure, Size, and Operating Torque

Floating valves are often considered for smaller or moderate-duty applications, while trunnion designs are frequently evaluated as size, pressure, or actuation demands rise. These are selection tendencies, not fixed limits: product ranges overlap, and manufacturers offer different designs. A nominal size alone cannot establish suitability.

Specify the maximum and minimum operating pressure, differential pressure across the closed valve, temperature range, and required cycle frequency. For example, a request for a 2 in (DN 50) valve is more useful when accompanied by the pressure class, medium, temperature, and end connection. That size is an illustrative procurement detail, not a rule that determines which ball support is correct.

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Sealing, Materials, and Service Conditions

Seat material and construction influence leakage performance, temperature suitability, chemical compatibility, and torque. Metal-seated and soft-seated options may behave differently, so avoid choosing a valve type based on the ball support alone. Confirm body, ball, stem, seat, and seal materials against the process medium and project requirements.

Also clarify whether the service involves abrasive particles, solids, corrosive media, frequent cycling, or potential pressure trapped in the body cavity. These conditions can affect seat wear and the required valve features. Ask the supplier to state the applicable leakage test basis and the proposed design provisions in the quotation or technical submittal.

Actuation and Installation

Both designs can be supplied for manual or actuated operation, depending on the product configuration. A quarter-turn ball valve uses approximately 90° of rotation between its open and closed positions, but the torque required to complete that movement varies by design and operating condition. For an actuator package, request the valve torque data across the specified pressure range and confirm the actuator’s sizing assumptions.

Installation constraints matter as well. Compare face-to-face dimensions, weight, access for operation or maintenance, mounting details, and the space available for an actuator. For a larger valve, these practical requirements can influence project cost and schedule as much as the basic valve type.

Application Suitability: Which Type Fits?

When to Consider a Floating Ball Valve

• The project calls for a compact, straightforward shutoff valve within the manufacturer’s stated size and pressure range.
• The operating torque and actuator requirements are manageable for the selected configuration.
• The process conditions are compatible with the offered seat and body materials.
• Budget, installation space, and maintenance access favor a simpler valve arrangement.

When to Consider a Trunnion-Mounted Ball Valve

• The valve is relatively large or operates at conditions where floating-ball torque may be a concern.
• The valve will be automated and the project requires carefully controlled actuator sizing.
• The specified pressure, service, and operating frequency match the manufacturer’s trunnion design.
• The project needs particular seat, cavity, or sealing features that are available in the offered configuration.

These lists are starting points, not substitutes for engineering review. A trunnion valve is not automatically the safer or more reliable choice, and a floating valve is not automatically limited to low-pressure service. Confirm compliance with the project’s governing standards, pressure-temperature ratings, inspection requirements, and end-user specifications.

Cost, Lead Time, and Sourcing Risk

Purchase price depends on more than the mounting style. Size, pressure class, materials, seat design, end connections, testing, actuation, and documentation can all affect the quotation. A floating design may be economical for a suitable application, while a trunnion design may justify its cost where the specified torque, size, or operating conditions call for it.

Lead time is likewise configuration-dependent and should be confirmed for the exact bill of materials. To reduce sourcing risk, send suppliers the datasheet or a complete inquiry schedule, including quantity, pressure and temperature, medium, operation type, connection standard, required documents, and delivery destination. Ask them to identify deviations from your specification instead of assuming that a general product description covers every requirement.

How to Make the Final Decision

1. Define the service: Record medium, pressure, temperature, flow direction, and any solids or corrosive components.
2. Set the valve requirements: Confirm size, pressure class, connection, materials, shutoff expectations, and applicable standards.
3. Compare torque and support: Review the manufacturer’s torque data and determine whether a floating or trunnion arrangement better suits the load and operating plan.
4. Check the complete package: Evaluate actuator, installation dimensions, testing, documentation, maintenance access, and delivery schedule.
5. Review the technical offer: Have the supplier confirm suitability for the stated conditions and list any assumptions or exclusions.

Final Recommendation

In short, select a floating ball valve when its seat-supported design meets the project’s pressure, size, torque, and service requirements. Select a trunnion-mounted ball valve when its supported ball and seat arrangement better matches larger or higher-load service, or when the verified torque requirements favor that design. The right choice is the one supported by the full operating data and the manufacturer’s technical confirmation—not a blanket preference for one type.

For a quotation or design review, share your operating conditions, valve size and pressure class, materials, connection requirements, and manual or automated operation needs with Kaiwei (凯维). Our team can use those details to help compare suitable configurations and clarify the information needed before you place an order.