Maintenance and servicing methods for check valves

I. Maintenance Method 

1. Leakage fault handling 

Seal inspection and replacement: If the seals (such as O-rings, gaskets) are aging, cracked or damaged, they should be replaced with components of the same original specification as soon as possible. 

Valve disc and valve seat repair: Inspect the mating surface of the valve disc and valve seat. If there is wear, scratches or corrosion, the surface smoothness should be restored using grinding tools, or the damaged parts should be replaced directly. 

Spring adjustment: For spring-loaded check valves, if the spring is loose or broken, a spring of the same specification needs to be replaced and the preload force should be adjusted to the design value. 

2. Handling of valve disc jamming 

Internal cleaning: Remove the valve, clean the accumulated dirt, welding slag or foreign objects in the valve chamber, and ensure that there is no obstruction to the movement of the valve disc. 

Component correction and replacement: If the valve disc is deformed, it needs to be corrected or replaced using specialized tools; when the guiding components (such as the guide rod and bushing) are worn, they need to be repaired or replaced to ensure the vertical movement of the valve disc. 

3. Vibration and Noise Control 

Pipeline optimization: Check whether the pipeline supports are firmly installed to avoid resonance; Install flexible joints or shock absorbers before and after the valves to reduce the transmission of vibrations. 

Flow rate control: By adjusting the system flow rate or replacing with larger-diameter valves, the flow velocity of the medium is controlled within a reasonable range (typically ≤ 3 m/s). 

Valve selection review: If the original valve selection was incorrect (such as the pipe diameter being too small), the system parameters need to be re-evaluated and an appropriate valve should be replaced. 

4. System pressure adjustment 

If the check valve fails to close tightly due to fluctuations in system pressure, a pressure stabilizing device (such as a buffer tank or a pressure reducing valve) should be installed at the pump outlet or in front of the valve to ensure that the pressure remains within the designed range. 

II. Maintenance Methods 

1. Daily inspection and cleaning 

Surface cleaning: Regularly wipe the surface of the valve body with a dry cloth to avoid using corrosive cleaners; inspect the valve body for cracks, rust or deformation. 

Internal cleaning: Every six months, remove the valve and use a dedicated cleaning agent to clean the valve disc, valve seat and valve chamber, removing oil stains, impurities and deposits; after cleaning, blow dry with compressed air and apply anti-rust oil. 

2. Regular replacement of seals 

Based on the frequency of use and environmental conditions, it is recommended to replace the seals every 1-2 years; in humid, high-temperature or corrosive medium environments, the replacement period should be shortened to 6-12 months. 

3. Rust Prevention and Lubrication 

Anti-rust treatment: Apply anti-rust paint or lubricating grease on the surface of the valve body, with particular attention to the corroded areas such as the threads and flange connection surfaces. 

Lubrication of moving parts: Regularly apply lubricating oil (such as lithium-based grease) to moving parts like valve rods and guide rods to reduce friction and wear. 

4. Long-term Storage Management 

Storage environment: Store the check valve in a dry and well-ventilated indoor area, avoiding direct sunlight and rain exposure; the storage temperature should be controlled between -10℃ and 40℃. 

Dust and rust prevention: Both ends of the pipe are blocked with foam boards, and the ports are sealed with plugs; the valve disc is fixed in the open position, and the pneumatic drive device is placed upright to avoid mutual compression. 

Regular inspection: Check the protective condition of the valve passage, sealing surface and welding joint once every three months. After cleaning off the dirt, reapply anti-rust oil. 

5. Operation Status Monitoring 

Regular pressure testing: Conduct a pressure test on the check valve once a year to verify its sealing performance and operational flexibility; the test pressure should be 1.5 times the design pressure, and the holding pressure time should be no less than 5 minutes. 

Data Record: Establish a valve maintenance file, documenting the time, content, and replaced components of each repair and maintenance, to provide a reference for subsequent maintenance. 

III. Maintenance and Care Tips 

1. Safe operation: Before maintenance, the upstream and downstream valves must be closed and the medium drained to ensure that the system is free of pressure. If the medium is flammable, explosive or toxic, additional safety precautions must be taken. 

2. Component Matching: When replacing seals or critical components, it is essential to use products of the same specification and material as the original ones. Failure to do so may result in leakage or jamming due to incompatibility. 

3. Professional Training: Maintenance personnel must undergo professional training to be familiar with the structure, principle and maintenance procedures of the check valve, in order to prevent damage to the valve due to improper operation. 

4. Preventive Maintenance: Based on the operating characteristics of the system, formulate a preventive maintenance plan. Regularly inspect and replace wear-prone components to extend the service life of the valves.