Valves are crucial components of industrial and civil facilities, widely used in industries such as petroleum, chemical, water supply, gas supply, power, and metallurgy. The primary function of valves is to control the direction, pressure, and flow rate of fluids, ensuring the safe and stable operation of the system. However, because valves operate in harsh environments such as high temperature, high pressure, and strong corrosion for extended periods, they are prone to wear, corrosion, and aging, leading to valve malfunction, leakage, or even safety accidents. Therefore, regular maintenance and upkeep are essential measures to ensure the long-term stable operation of valves.
This article will detail the methods for regular valve maintenance and upkeep, including inspection, cleaning, lubrication, adjustment, and repair, to help users extend valve lifespan and improve system efficiency and safety.

I. The Importance of Regular Valve Maintenance

During operation, valves are affected by various factors such as pressure, temperature, and media. After prolonged operation, various problems can easily occur, such as seal failure, malfunctioning opening and closing, valve seat wear, and corrosion. Regular maintenance and upkeep not only allows for the timely detection and repair of potential faults but also ensures the valve's sealing performance, reliability, and operational efficiency.
Extending Valve Lifespan: Regular inspection and maintenance can effectively slow down valve aging and wear, reducing damage caused by long-term use.
Ensuring System Safety: Valve malfunctions can lead to serious accidents such as fluid leaks, fires, and explosions. Regular maintenance helps identify potential problems early and prevent accidents.
Improving Work Efficiency: Valves are a crucial component of fluid control systems. Good valve maintenance ensures smooth system operation and prevents production stoppages or inefficiencies caused by valve malfunctions.

II. Periodic Valve Inspection
Periodic inspection is the first step in valve maintenance, primarily aimed at identifying and addressing potential problems proactively. Valve inspection should include visual inspection, functional inspection, operational status inspection, and sealing inspection.

1. Visual Inspection
Visual inspection is the simplest and most basic method, helping to identify obvious faults such as corrosion, leakage, and cracks.
Shell and Connections: Inspect the valve shell for cracks, deformation, corrosion, or other damage. Check all valve connections (such as flange connections, threaded connections, etc.) for tightness and looseness.
Valve Markings and Nameplates: Ensure the markings and nameplates on the valve are clearly visible. Check that the valve model, pressure rating, temperature range, etc., meet the usage requirements.
Sealing Components: Inspect the sealing surfaces for wear, cracks, or aging. Ensure the sealing rings are intact.

2. Functional Inspection
Functional inspection primarily involves operating the valve to check its ability to open and close normally and operate smoothly.
Opening and Closing Flexibility: Check whether the valve opening and closing operation is smooth and whether excessive force is required to complete the operation. If the valve is difficult to open and close, it may be due to jamming or wear of internal components.
Manual Operation Check: If the valve is manually operated, open and close it manually to check for any jamming, abnormal noises, or excessive resistance.
Automatic Control Check: For electric or pneumatic valves, check if the automatic control system is operating normally, if signal transmission is sensitive, and if the actuator responds normally.

3. Sealing Check

The sealing performance of the valve directly affects the safety and economy of the system; therefore, regular sealing checks are essential.
Leak Detection: Check for leaks at the valve's sealing surfaces. For fluid pipelines, gas leak detectors and temperature change checks are commonly used to check the valve's sealing performance.
Sealing Material Check: Check for aging, wear, or damage to sealing rings, O-rings, and other sealing components to ensure effective sealing.

4. Operational Status Check

The operational status check evaluates the valve's performance under actual operating conditions, primarily by observing operational data to check for any abnormalities.
Flow and pressure monitoring: Monitor the flow and pressure downstream of the valve using flow meters and pressure gauges to check if the valve can regulate flow and pressure normally within the specified range.
Temperature monitoring: Monitor temperature changes around the valve to check for overheating or undercooling. High temperatures accelerate the aging of sealing materials, while excessively low temperatures may cause the valve to freeze or malfunction.

III. Valve Cleaning and Lubrication

During long-term operation, valves accumulate dirt or deposits due to factors such as media erosion, fluid corrosivity, and temperature variations. These deposits may affect normal valve operation. Therefore, regular cleaning of the valve's interior and exterior is essential.
1. Internal Cleaning
The cleaning of the valve's interior should be tailored to the specific media type and the valve's operating environment. For valves handling liquid media, regular cleaning prevents the accumulation of dirt and deposits, ensuring unobstructed fluid flow.
Remove Deposits: Use a specialized cleaning agent to remove scale and deposits from inside the valve. Pay particular attention to removing deposits from the valve body and sealing surfaces when handling media containing particles.
Inspect Valve Seat and Core: The valve seat and core are critical sealing components. Regularly inspect and clean dirt, corrosion, or deposits from these parts to ensure effective sealing.
2. External Cleaning
External cleaning of the valve's exterior primarily removes dust, oil, and corrosive substances resulting from exposure to harsh environments. Cleaning the valve exterior helps extend its service life and prevents corrosion or damage caused by external contaminants.
Use a Soft Cloth: Wipe the valve's external surface with a clean, soft cloth. Avoid using hard objects to scrape the surface to prevent scratches.
Remove Dirt and Oil Stains: Clean dirt and oil stains around the valve to prevent corrosion of the sealing components.
3. Lubrication
For moving parts, such as valve bearings and stems, regular lubrication reduces friction and wear, ensuring smooth valve operation.
Lubricant Selection: Select appropriate lubricant or grease based on the valve's operating environment and materials. High-temperature resistant lubricants should be used in high-temperature and high-pressure environments.
Lubrication Points: Regularly lubricate valve bearings, stems, and other components to ensure smooth valve opening and closing.

IV. Valve Adjustment and Repair
After prolonged use, valves may experience performance degradation, such as poor sealing, malfunctioning opening and closing, or valve body damage. Regular adjustment and repair can restore normal valve function and prevent minor issues from escalating into major malfunctions.
Sealing Surface Adjustment
The sealing surface is a crucial part of the valve's sealing performance. Prolonged use can lead to wear, deformation, or corrosion of the sealing surface, affecting the valve's sealing performance. In such cases, repair or replacement of the sealing surface is necessary.
Grinding the Sealing Surface: Grinding the sealing surface removes scratches, pits, and other defects, making the sealing surface smoother and improving sealing performance.
1. Replace the sealing ring: If the sealing ring is aged or damaged, it needs to be replaced with a new one promptly.
2. Adjust the valve's opening and closing stroke: During use, wear or uneven sealing surfaces may cause deviations in the valve's opening and closing stroke. In this case, the valve stem or valve actuator needs to be adjusted to restore the normal opening and closing stroke.
3. Replace damaged parts: During regular inspections, if certain valve parts are found to be damaged or severely worn, they need to be replaced promptly. For example, replacing parts such as the valve stem, valve seat, valve core, and sealing rings can effectively restore the valve's performance.

V. Summary

Regular maintenance and upkeep of valves are crucial for their long-term stable operation. Regular inspection, cleaning, lubrication, adjustment, and repair ensure that valves maintain good working condition under various operating conditions, extending their service life and improving system safety and reliability. Different types of valves require different maintenance measures depending on their specific operating conditions. Therefore, valve maintenance should be tailored to the valve type, working environment, and factors such as pressure and temperature.