Choose a floating ball valve when its size and pressure conditions suit a ball supported by the seats; choose a trunnion ball valve when a mechanically supported ball is better suited to the required size, pressure, or operating torque. The key difference is how the ball is supported and how sealing force is created. Both designs typically operate with a quarter-turn movement of 90°, but neither is universally superior. Your selection should account for pressure, temperature, media, operating frequency, end connections, and the applicable project specifications.
This comparison focuses on the two common ball-support arrangements used in industrial isolation service. Actual performance depends on the valve’s design, materials, seat construction, dimensions, and operating conditions, so product data should be checked for the specific model. A valve’s name alone does not confirm its pressure rating, leakage performance, or suitability for a particular fluid. Use the comparison as a starting point for a technical review rather than as a substitute for sizing and specification checks.
| Feature | Floating ball valve | Trunnion ball valve |
|---|---|---|
| Ball support | The ball is not fixed by a trunnion; it can move slightly under pressure. | The ball is supported by a stem and lower trunnion or equivalent bearing arrangement. |
| Sealing action | Line pressure can push the ball against the downstream seat. | Seats move or load against the supported ball, according to the design. |
| Operating torque | Can increase as pressure and seat loading increase. | Often selected where reduced torque is valuable, especially in larger or higher-pressure designs. |
| Typical selection emphasis | Compactness and suitable performance for the specified service. | Ball support, operating loads, and suitability for demanding or larger-bore service. |
A floating ball valve uses a ball held in position primarily by the seats and body geometry rather than by a lower trunnion. When the valve is closed, pressure from the upstream side may move the ball toward the downstream seat, helping create the seal. This pressure-assisted action is part of the design principle, but the resulting shutoff performance depends on seat materials, pressure differential, fluid properties, and the valve’s construction. Higher seat loading can also mean greater friction and operating torque.
A trunnion ball valve supports the ball at the stem and a lower trunnion or another engineered support arrangement. Instead of relying on the ball to shift downstream in the same way, the design typically uses seats that load against the supported ball. This arrangement can reduce the load transferred through the ball to the seats and may help manage operating torque in larger or higher-pressure valves. Exact behavior varies by manufacturer and seat design, so buyers should review the product’s torque and pressure data.
Both valve types can be used for on-off isolation in many industrial systems when the selected model is rated for the service. Common considerations include the design pressure and temperature, fluid compatibility, required leakage performance, fire-safe or emissions requirements where specified, and the desired end connection. Materials such as carbon steel, stainless steel, and other alloys are selected according to the fluid, environment, and project specification; no material should be assumed suitable without a compatibility review. If the valve will be automated, actuator sizing must use the manufacturer’s torque data for the actual operating conditions.
| Selection factor | Floating valve: points to review | Trunnion valve: points to review |
|---|---|---|
| Pressure and differential pressure | Confirm the valve and seats are rated for the full operating envelope. | Confirm the design rating and seat behavior for the specified pressure conditions. |
| Size and torque | Check operating torque carefully, especially as size or pressure increases. | Review torque, bearing, and actuator requirements for the exact size and configuration. |
| Service conditions | Verify materials, seat compatibility, temperature, and media characteristics. | Apply the same compatibility checks and confirm the support design suits the service. |
| Maintenance and operation | Confirm the maintenance plan and access requirements for the selected construction. | Review seat and support components, serviceability, and any project-specific inspection needs. |
A floating design may be appropriate when the required valve size, pressure rating, and operating torque fall within the manufacturer’s stated limits. It can be a practical option for isolation duties where the specification favors a comparatively straightforward arrangement and the service does not require the particular support approach of a trunnion design. For example, a buyer evaluating a 2-inch line might include floating valves in the comparison, but that nominal size alone does not establish suitability. Pressure, temperature, seat selection, and the valve’s certified product data remain decisive.
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A trunnion design is often considered for larger-bore or higher-pressure applications where supporting the ball and managing operating loads matter to the design. A 20-inch pipeline is an illustrative case in which buyers commonly examine trunnion options, but it is not a universal size threshold or a recommendation independent of project data. The required pressure class, operating torque, actuation method, and service conditions must still be checked. Where frequent operation or automation is involved, request torque values for the relevant differential pressure and temperature.
Purchase price cannot be compared reliably from valve type alone. Size, pressure rating, body and trim materials, seat design, end connections, testing scope, documentation, and actuator requirements all affect the quotation. A trunnion valve may involve a different construction and component set, but the cost difference depends on the exact specification and supplier, so buyers should compare like-for-like offers rather than assume one design is always cheaper.
Lead time also depends on configuration, material availability, production capacity, inspection requirements, and order quantity. To reduce sourcing risk, send suppliers a complete datasheet or valve schedule, including line size, pressure and temperature, fluid, connection standard, operating method, and required documents. Ask each supplier to identify deviations from the specification and confirm the offered design, materials, and test scope in writing. This makes technical and commercial comparisons more meaningful.
In short, floating ball valves use pressure-driven movement of the ball toward a seat, while trunnion ball valves support the ball and use a different seat-loading arrangement. Floating designs may suit applications within their specified size, pressure, and torque limits; trunnion designs are often evaluated when larger size, higher pressure, or operating-load considerations make ball support important. Neither description alone guarantees better sealing, longer service life, or lower total cost. The right choice is the model that meets the full operating and project specification.
Before requesting a quotation, prepare the valve size, design pressure and temperature, fluid details, connection requirements, operating frequency, actuation method, and documentation needs. Ask the supplier to confirm the proposed construction, material and seat compatibility, pressure rating, torque data, testing scope, lead time, and any deviations. Kaiwei (凯维) can support B2B buyers by reviewing these selection inputs and discussing suitable valve configurations for the stated project requirements. Share your valve schedule or operating conditions to begin a focused technical and commercial comparison.
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