Solutions To The Problem of Excessive Switching Torque of Ball Valves: A Comprehensive Analysis From Valve Body Structure To Actuator Selection

I. ANALYSIS OF THE CAUSES OF EXCESSIVE SWITCHING TORQUE OF BALL VALVES

(A) Problems with the Valve Body Structure

• Unreasonable Sealing Structure: Insufficient machining accuracy of the sealing surface or improper selection of sealing materials will lead to an increase in the friction between THE BALL AND THE VALVE SEAT, thereby increasing the switching torque.

• Fit Problems between the Ball and the Valve Seat: The dimensional accuracy and surface roughness of THE BALL AND THE VALVE SEAT have a direct impact on the switching torque. An overly small clearance will increase the friction, while an overly large clearance may lead to medium leakage.

• Friction between the Valve Stem and the Packing: The material of the packing, the degree of compression, and the surface treatment of the valve stem will all affect the friction between them. If the packing is compressed too tightly or the material is improperly selected, the friction will increase.

(B) Improper Actuator Selection

• Insufficient Output Torque of the Actuator: If the output torque of the actuator is less than the switching torque required by the BALL VALVE, it will result in the valve being unable to open or close normally, and may even damage the actuator.

• Mismatch of Actuator Types: Different types of actuators are suitable for different application scenarios. For example, for large-diameter or high-pressure ball valves, fork-type pneumatic actuators or electric actuators should be preferentially selected.

• Unreasonable Actuator Control Mode: On-off control type actuators are suitable for simple operations, while modulating control type actuators have more precise flow regulation capabilities. Improper selection of the control mode may lead to switching jams or insufficient torque.

II. OPTIMIZATION SCHEMES FOR THE VALVE BODY STRUCTURE

(A) Optimize the Sealing Structure

• Improve the Machining Accuracy of the Sealing Surface: Adopt high-precision machining equipment and processes to ensure that the sealing surfaces of the valve seat and the ball are flat and smooth, reducing friction.

• Select Appropriate Sealing Materials: According to the working medium and temperature conditions, select sealing materials that are resistant to high temperatures and corrosion to reduce wear and friction.

• Optimize the Design of the Sealing Structure: Adopt advanced designs such as elastic seals or floating valve seats to improve the sealing performance while reducing friction.

(B) Adjust the Fit between the Ball and the Valve Seat

• Precise Control of Dimensional Accuracy: Strictly control the dimensional accuracy of THE BALL AND THE VALVE SEAT to ensure a reasonable fit clearance.

• Optimize the Surface Treatment Process: Adopt processes such as polishing, sandblasting, and coating to improve the surface smoothness and hardness and reduce the friction coefficient.

(C) Improve the Friction between the Valve Stem and the Packing

• Reasonably Select the Packing Material: According to the working conditions and medium characteristics, select packing materials that are resistant to high temperatures and corrosion, such as graphite or polytetrafluoroethylene.

• Adjust the Degree of Packing Compression: Reasonably control the degree of packing compression to avoid being too tight or too loose.

• Optimize the Surface Treatment of the Valve Stem: Adopt processes such as hard chrome plating and spray coating to improve the surface hardness and smoothness of the valve stem and reduce friction.

III. ACTUATOR SELECTION SCHEMES

(A) Reasonably Select the Actuator Type

• Pneumatic Actuator: It is suitable for large-diameter and high-pressure ball valves, with a large output torque and quick action.

• Electric Actuator: It is suitable for ball valves with high requirements for switching accuracy, with a large output torque and high control accuracy.

• Hydraulic Actuator: It is suitable for super-large-diameter and ultra-high-pressure ball valves, with a large output torque and stable action.

(B) Ensure the Matching of the Actuator's Output Torque

• Accurately Calculate the Switching Torque: Combine the actual working conditions to accurately calculate the switching torque required by the BALL VALVE.

• Consider the Safety Factor: According to the type of medium, increase the corresponding safety factor to ensure that the actuator can reliably drive the ball valve to open and close.

• Match the Torque Characteristic Curve: Select an actuator whose output torque characteristic curve is similar to that of the ball valve's switching torque.

(C) Optimize the Actuator's Control Mode

• Select an Appropriate Control Mode: According to the application scenario and control requirements, select an on-off control type or a modulating control type actuator.

• Equip with Signal Feedback Function: In occasions where real-time monitoring of the state of the ball valve is required, select an actuator with a signal feedback function.

IV. CONCLUSION

To solve the problem of excessive switching torque of ball valves, it is necessary to start from two aspects: optimizing the valve body structure and selecting the actuator. By optimizing the sealing structure, adjusting the fit between THE BALL AND THE VALVE SEAT, improving the friction between the valve stem and the packing, and reasonably selecting the actuator type, ensuring the matching of the output torque, and optimizing the control mode, the switching torque of the ball valve can be effectively reduced, and the operation convenience and the service life of the equipment can be improved.