How to implement regulating valve diagnosis

As a key actuating element in industrial process control, the operating status of the regulating valve directly affects the control accuracy, production efficiency, and safety of the system. With the continuous improvement of industrial automation levels, the online diagnosis and status monitoring technology of regulating valves has received increasing attention. This article will discuss how to effectively implement regulating valve diagnosis from aspects such as the purpose of diagnosis, common fault types, diagnostic methods, and implementation steps.

The purpose of regulating valve diagnosis

The main purpose of regulating valve diagnosis is to detect potential faults or performance degradation trends in real-time through the monitoring and analysis of valve operating status, in order to prevent unplanned downtime and improve equipment reliability and maintenance efficiency. Through diagnosis, key parameters such as valve leakage, response speed, positioning accuracy, and friction force changes can be judged, providing a scientific basis for predictive maintenance.

Two, Common fault types of regulating valves

Possible failures of regulating valves during operation mainly include:

1. Leakage: due to wear of the valve core and seat or aging of the sealing parts, medium leakage occurs.
2. Hysteresis and back lash: valve response is not sensitive, and there is a phenomenon of action lag.
3. Sticking and friction abnormalities: valve stem sticking or increased friction force affects control accuracy.
4. Inaccurate positioning: feedback signal does not match the actual opening, affecting the stability of the control loop.
5. Abnormal air or power supply: unstable power supply of the drive device leads to abnormal operation.

Three, Methods of regulating valve diagnosis

The diagnostic methods of regulating valves are mainly divided into online diagnosis and offline detection:

1. Online diagnosis: use intelligent locators, built-in sensors of actuators, or external testing equipment to collect and analyze various parameters of the valve in operation.
2. Offline detection: after the valve is removed from the system, functional tests and leakage detection are carried out in the laboratory or maintenance station.

Online diagnostic technology is widely adopted due to its non-disruptive production and rapid response, and mainly includes the following technologies:

- Pressure and flow monitoring: analyze the relationship between the pressure difference before and after the valve and the flow change to determine whether there is leakage or blockage.
- Stroke and positioning signal analysis: by comparing the control signal with the actual valve position feedback, identify issues such as hysteresis and dead zones.
- Vibration and noise analysis: abnormal vibration or noise may reflect internal wear or flow instability inside the valve.
- Friction test: measure the relationship between the output force of the actuator and the friction force of the valve stem to evaluate the degree of internal wear.

Four, Specific implementation steps of regulating valve diagnosis

1. Establish diagnostic plans: based on system importance and valve operating environment, formulate regular diagnostic plans and priorities.
2. Prepare data collection: configure intelligent locators, sensors, and data collection equipment to ensure data accuracy.
3. Execute diagnostic tests: according to the predetermined process, collect parameters such as opening response tests, leakage tests, and friction tests.
4. Data analysis and evaluation: use professional software to process collected data, identify abnormal patterns, and evaluate the health status of the valve.
5. Generate diagnostic reports: summarize diagnostic results, and propose maintenance suggestions or replacement plans.
6. Subsequent maintenance and tracking: targeted maintenance based on diagnostic results, and continuous tracking of improvement effects.

Five, Conclusion

Diagnosis of regulating valves is an important link to ensure the stable operation of automatic control systems. Advanced diagnostic technology not only improves equipment operating efficiency but also significantly reduces maintenance costs and fault risks. In the future, with the development of technologies such as artificial intelligence and big data, the intelligent diagnosis of regulating valves will become more accurate and efficient, laying a solid foundation for enterprises to achieve digital and intelligent operation and maintenance.