1. Floating ball valve
Structural Features
Ball support method:
The ball is only connected to the drive device through the valve stem, and there is no bottom mechanical support.
Under the action of the medium pressure, the ball can float toward the downstream valve seat and press the valve seat to achieve sealing (mainly one-way sealing).
Sealing principle:
The medium pressure pushes the ball to squeeze the downstream valve seat (spring preload assistance) to form a sealing force.
Main Features:
| Item |
Description |
| Application nominal Diameter |
≤ DN 200mm |
| Pressure Rating |
Medium and Low Pressure(Class150~600) |
| Operating Torque |
Higher (Greater operating force is required under high pressure) |
| Flow Direction |
Install in the direction of body arrow (seal depends on downstream pressure) |
| Cost |
The structure is simple and the cost is low |
| Typical Standard |
API 608(Refining and chemical, general Industries) |
Application
Water treatment, low-pressure steam, general chemical fluids (non-abrasive).
Not Applicable:
❌ Large-diameter high-pressure pipelines (excessive torque)
❌ Bidirectional sealing harsh working conditions (such as long-distance pipelines)
2. Trunnion Mounted Ball Valve
Structural Features
Ball support method:
The ball is fixed to the valve body by two upper and lower pivots (Trunnion) to form a mechanical support, and the ball cannot float.
Sealing Principle:
The valve seat is pressed against the ball by the spring preload + medium pressure (bidirectional sealing), and the sealing force is positively correlated with the pipeline pressure.
Additional Safety Design:
Valve stem anti-blowout structure (API 6D mandatory requirement)
Middle cavity overpressure relief device (DBB function)
Main Features:
| Item |
Description |
| Application nominal Diameter |
≤ DN 15~1200mm+ |
| Pressure Rating |
High Pressure(Class150~2500) |
| Operating Torque |
Lower (Only 10%~20% of the floating ball valve, suitable for pneumatic/electric control) |
| Sealing Direction |
Two-way sealing |
| Complexity of structure |
High (with pivoting, spring-loaded seats, etc.) |
| Typical Standard |
API 6D |
Application:
Long-distance oil/gas pipelines (API 6D mandatory requirement)
High pressure, large diameter, bidirectional sealing and harsh working conditions (such as Class 600 and above)
Full-bore pipelines that require pigs to pass (PIG Passable)
Pictures of Floating Ball Valve and Trunnion Mounted Ball Valve
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