Guide to Control Valve Selection Use and Maintenance

In complex industrial systems, fluids flow through pipelines like blood through veins, with control valves serving as the "intelligent switches" that precisely regulate flow and pressure to ensure stable operation. However, the market offers a bewildering array of control valves—manual, pneumatic, electric—and improper selection can range from affecting production efficiency to creating safety hazards. This comprehensive guide explores the world of control valves from selection to application and maintenance.

The domestic valve industry has seen significant advancement in recent years, with numerous high-quality manufacturers emerging. Industry conferences have summarized developmental achievements while charting future directions. Major projects including high-pressure control valves for petrochemical storage facilities and advanced manufacturing initiatives demonstrate domestic capabilities in high-end valve production. Breakthroughs in specialized applications, such as cryogenic control valves for LNG operations, highlight the sector's technical progress.

Control valves are primarily categorized by their actuation method:

Featuring simple structures and low costs, these are suitable for applications requiring minimal precision where manual operation is practical.

With rapid response times and high precision, these valves are ideal for frequent adjustments but require compressed air supplies.

Capable of remote operation and high automation levels, these suit large-scale control systems despite their relatively higher costs.

Proper valve selection requires careful evaluation of multiple factors. These key questions guide decision-making:

• Medium Characteristics: Type, temperature, pressure, and corrosivity influence material selection for valve bodies and seals.
• Flow Characteristics: Process requirements determine whether linear, equal percentage, or quick-opening characteristics are needed.
• Port Size: Proper sizing relative to pipeline dimensions and flow rates ensures effective control.
• Pressure Drop: System requirements dictate appropriate valve specifications.
• Actuator Type: Control precision and response needs determine suitable actuators.
• Body Material: Medium corrosivity dictates material choices like stainless steel or alloy options.
• Sealing Configuration: Leakage requirements guide soft or hard seal selection.
• Connection Method: Pipeline interfaces determine flange, threaded, or welded connections.
• Operating Environment: Temperature, humidity, and explosion-proof needs influence specifications.
• Brand and Support: Reputable manufacturers with reliable service ensure long-term performance.

Control valves serve critical roles across petroleum, chemical, power, metallurgical, and pharmaceutical industries. Key operational considerations include:

Strict adherence to installation guidelines ensures proper positioning and orientation.

Pre-operation checks should verify component integrity and tight connections, with gradual parameter adjustments during testing.

Regular inspections should monitor operational status, clear internal debris, and replace worn components. Pneumatic systems require additional air supply monitoring.

Pressure testing represents a crucial quality assurance step. Sixteen essential principles govern proper testing procedures:

1. Verify valve specifications against requirements
2. Use clean, non-corrosive testing media
3. Maintain standard-compliant test pressures
4. Apply pressure gradually without shock
5. Monitor all components for leaks
6. Depressurize slowly post-testing
7. Document all test parameters and results
8. Employ qualified testing personnel
9. Maintain calibrated testing equipment
10. Secure testing areas with proper signage
11. Use appropriate personal protective equipment
12. Immediately address any abnormalities
13. Record results in technical documentation
14. Only deploy pressure-tested valves
15. Conduct specialized tests for extreme conditions
16. Prioritize safety throughout all operations

As indispensable components in industrial automation systems, control valves demand careful selection, proper application, and diligent maintenance. Understanding these operational principles helps ensure reliable performance across diverse industrial applications.