Key Factors Affect Ball Valve Torque Value

1. Seat Material (Major Influence)

• Soft seats (PTFE, PEEK, Nylon, Delrin): Lower friction → lower torque
• Metal seats (Stainless Steel, Inconel): Higher friction → higher torque

2. Ball Material & Surface Finish

• Smooth chrome-plated or polished balls reduce friction → lower torque.
• Rough or coated balls (e.g., tungsten carbide) increase friction → higher torque.

3. Seal Type & Design

• Floating ball valves rely on seat compression → higher torque.
• Trunnion-mounted ball valves reduce seat friction → lower torque.
• Spring-loaded seats maintain sealing with less torque increase over time.

4. Operating Pressure & Differential Pressure (ΔP)

• Higher upstream pressure forces the ball against the seat → increases torque.
• High ΔP (pressure drop) requires more force to break the seal → higher breakaway torque.

5. Valve Size (Bore Diameter)

• Larger valves (e.g., 12" vs. 2") have more surface area → higher torque.
• Torque typically increases with the square of the diameter.

6. Temperature Effects

• Cold environments: Soft seats (PTFE) harden → higher torque.
• High temperatures: Metal seats expand → possible galling, increasing torque.

7. Lubrication & Coatings

• Dry operation (no lubrication) increases friction → higher torque.
• Self-lubricating seats (graphite-filled PTFE) reduce torque.
• Coatings (e.g., DLC, Teflon) lower friction.

8. Stem Design & Packing Friction

• Stem sealing (graphite, PTFE packing) adds resistance.
• Stem diameter & length: Thicker/longer stems require more torque.

9. Actuation Method (Manual, Pneumatic, Electric)

• Manual valves: Torque affects handle effort.
• Automated valves: Must match actuator torque rating.

Summary of Dominant Factors:

How to Reduce Torque?

✔ Use PTFE/PEEK seats for low friction.
✔ Choose trunnion-mounted ball valve for large/high-pressure valves.
✔ Ensure smooth ball surface finish.
✔ Consider self-lubricating coatings.
✔ Select proper actuator sizing for automated valves.