api 6d trunnion mounted ball valve
The API 6D trunnion ball valve is a special type of ball valve with a key feature: unlike a floating ball valve, the ball does not move freely but is fixed inside the valve body by two or more trunnions (usually bearings). This design ensures the ball remains in a fixed position during opening and closing, preventing direct friction between the ball and the valve seat, thus significantly reducing seat wear and extending the valve's service life. Furthermore, the trunnion structure can withstand higher pressures, making trunnion ball valves suitable for high-pressure, large-diameter applications.
Specification
Structural Features
- Truncate Support Design
The ball is fixed to the valve body on both sides by trunnions (short shafts), unlike the free-floating design of traditional floating ball valves.
The trunnions are supported by the medium pressure, preventing excessive compression between the ball and the valve seat, reducing wear, and extending service life.
- Bidirectional Sealing
Imported trunnion ball valves typically employ a bidirectional sealing structure, achieving reliable sealing regardless of the medium flow direction.
The valve seat is designed with a spring-loaded or self-sealing structure to adapt to pressure fluctuations and temperature changes.
- Large Diameter and High Pressure Adaptability
Can be designed for DN50~DN1200 (2"~48") or even larger diameters, with pressure ratings covering Class 150~Class 2500 (PN16~PN420).
The trunnion support disperses the medium pressure, making it suitable for high-pressure, high-temperature, or corrosive media conditions.
- Fire Safety Design
The valve seat material typically includes a composite structure of metal and soft seals (such as PTFE). In the event of a fire, the metal portion can form an emergency seal to prevent leakage.
Working Principle
Open State
Rotate the valve stem 90°, aligning the ball channel with the pipeline, minimizing medium flow resistance and reducing pressure drop.
Closed State
Rotate the ball 90° to a vertical position, ensuring a tight seal between the valve seat and the ball surface, cutting off medium flow.
Trundle support ensures the ball does not shift under high pressure, maintaining sealing performance.
Application Scenarios
- Oil and Gas Industry
Oil pipelines, natural gas processing plants, refineries, etc., used to control high-pressure oil and gas media.
- Chemical and Petrochemical Fields
Pipeline systems handling corrosive media (such as acids, alkalis, solvents), requiring valves resistant to chemical corrosion.
- Power Industry
Steam pipelines, boiler feedwater systems, and other high-temperature, high-pressure conditions.
Water Treatment and Municipal Engineering
Large water supply pipelines, sewage treatment plants, etc., requiring large-diameter, low-leakage valves.
Advantages and Limitations
Advantages:
High Reliability: Trunnion support reduces ball shift, ensuring stable sealing performance.
Long lifespan: Low-friction design reduces wear and extends maintenance intervals.
High adaptability: Customizable with special materials such as high-temperature resistant, corrosion-resistant, and explosion-proof materials.
Low operating torque: Trunnion structure reduces opening and closing torque, facilitating automated control.
Limitations:
Higher cost: Complex structure, high-quality materials, and generally higher price than floating ball valves.
Heavier weight: Large-diameter valves require consideration of installation space and support structure.
High installation accuracy requirements: Ensure concentricity between the trunnion and valve seat to prevent leakage.
Selection and Maintenance Recommendations
Selection Points
Media characteristics: Select valve body material (e.g., carbon steel, stainless steel, alloy steel) based on temperature, pressure, and corrosiveness.
Sealing requirements: Determine whether a soft seal (zero leakage) or a hard metal seal (high-temperature conditions) is required.
Operation method: Manual, pneumatic, electric, or hydraulic actuation, selected based on automation requirements.
Maintenance Recommendations
Regular inspection: Check valve seat sealing and trunnion lubrication every 6-12 months.
Cleaning and maintenance: Remove deposits from the valve body to prevent impurities from abrading the ball surface.
Replace seals: Replace the valve seat seals every 3-5 years, depending on usage frequency.
valve in stock
