How to Extend the Service Life of Control Valves

As indispensable equipment in industrial production, control valves are widely used in various process flows. Their service life directly affects production stability and operating costs.

Proper selection is the foundation for extending the service life of control valves.

1.Working conditions impose vastly different requirements on control valves. Therefore, during model selection, full consideration shall be given to the properties of process media, such as temperature, pressure, corrosivity and viscosity. For high-temperature and high-pressure media, control valves with materials and structures capable of withstanding corresponding working conditions shall be selected. For corrosive media, corrosion-resistant materials such as stainless steel and ceramics shall be adopted.

2.Accurately calculate the valve size according to parameters including flow rate and pressure differential, to avoid oversized or undersized valves. An oversized valve often operates at a small opening, which easily causes wear on the valve plug and seat. An undersized valve fails to meet process requirements and runs under overload for a long time, shortening its service life.

3.Adopt specially designed structures or select valves with longer service life to achieve the goal of life extension, such as multi-stage pressure reducing valves, anti-cavitation valves and corrosion-resistant valves.

Correct installation and commissioning are also critical to the service life of control valves.

4.Install control valves in strict accordance with the installation manual. Ensure the valve is installed at a position convenient for operation and maintenance, and avoid locations with severe vibration or excessively high/low temperatures. For pipe connections, guarantee pipe concentricity to prevent extra stress on the control valve caused by improper pipe installation, which may impair normal operation. After installation, conduct comprehensive commissioning covering valve stroke, tightness, flow characteristics and other items, to ensure the control valve is in optimal working condition before commissioning.

5.For flow-to-open type valves, the fluid flows toward the opening direction. Cavitation and erosion mainly act on the sealing surface, which rapidly damages the root of the valve plug and the sealing surfaces of the plug and seat. For flow-to-close type valves, the fluid flows toward the closing direction. Cavitation and erosion occur after throttling, below the valve seat sealing surface. This protects the sealing surface and valve plug root and extends service life.

Routine maintenance is a key step to prolong the service life of control valves.

6. It is recommended to establish a complete maintenance system and inspect and service control valves periodically. Check for damage, corrosion and other defects on the valve exterior; inspect whether seals are aged or leaking, and replace faulty components promptly. Lubricate the actuator regularly to ensure smooth movement. Inspect and calibrate the control system of the control valve to guarantee accurate and stable control signals. Keep the process media clean to prevent impurities and particles from entering the valve interior and causing abrasion to the valve plug and seat.

Optimizing operating conditions can also effectively extend the service life of control valves.

7. Avoid operating control valves under extreme working conditions as much as possible. For example, prevent long-term operation at small or large openings. At small openings, the medium flows at high velocity, which tends to scour and wear the valve plug and seat. At large openings, the control valve exhibits poor stability, which also reduces its service life. Adjust process parameters so that the control valve operates within a reasonable opening range. Limit the fluctuation range of process medium flow, pressure and other parameters to avoid impact on the valve caused by excessive fluctuations.

Timely repair and upgrading are important measures to ensure long-term stable operation of control valves.

8. Carry out repairs promptly when faults or wear occur. Replace severely worn components such as valve plugs and seats in a timely manner. With continuous technological advances, upgrade and retrofit control valves by adopting more advanced materials, structures and control technologies to improve valve performance and service life.