Repair and maintenance methods for check valves

1、 Repair method

1. Leakage fault handling

Seal inspection and replacement: If the seal (such as O-ring, gasket) ages, cracks or is damaged, it is necessary to replace it with a component that matches the original specifications in a timely manner.

Valve disc and valve seat repair: Check the mating surface between the valve disc and valve seat. If there is wear, scratches, or corrosion, use grinding tools to repair the surface flatness or replace damaged parts directly.

Spring adjustment: For spring type check valves, if the spring is loose or broken, it is necessary to replace it with a spring of the same specification and adjust the preload to the design value.

2. Valve disc blockage treatment

Internal cleaning: Disassemble the valve, remove dirt, welding slag, or foreign objects from the valve chamber, and ensure unobstructed movement of the valve disc.

Component correction and replacement: If the valve disc is deformed, special tools need to be used for correction or replacement; When the guiding components (such as guide rods and bushings) wear out, they need to be repaired or replaced to ensure the vertical movement of the valve disc.

3. Vibration and noise treatment

Pipeline optimization: Check whether the pipeline support is firm and avoid resonance; Install flexible joints or shock absorbers before and after the valve to reduce vibration transmission.

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

Valve selection review: If the original valve selection is improper (such as a small diameter), the system parameters need to be re evaluated and suitable valves replaced.

4. System pressure adjustment

If the check valve does not close tightly due to system pressure fluctuations, a stabilizing device (such as a buffer tank or pressure reducing valve) should be installed at the pump outlet or valve front end to ensure that the pressure is stable within the design range.

2、 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 cleaning agents; Check the valve body for cracks, rust, or deformation.

Internal cleaning: Disassemble the valve every six months and clean the valve disc, valve seat, and valve chamber with a specialized cleaning agent to remove oil stains, impurities, and deposits; After cleaning, blow dry with compressed air and apply rust proof oil.

2. Regular replacement of seals

It is recommended to replace the seals every 1-2 years based on usage frequency and environmental conditions; In humid, high-temperature, or corrosive media environments, the replacement cycle should be shortened to 6-12 months.

3. Rust prevention and lubrication

Rust prevention treatment: Apply rust proof paint or lubricating grease on the surface of the valve body, paying special attention to corrosive parts such as threads and flange connection surfaces.

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

4. Long term storage management

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

Dust and rust prevention: both ends of the drift diameter are blocked with foam plates, and the ports are sealed with closed covers; The valve disc is fixed in the open position, and the pneumatic drive device is placed upward to avoid mutual compression.

Regular inspection: Check the protective condition of valve channels, sealing surfaces, and welding interfaces every 3 months, wipe off dirt, and reapply rust proof oil.

5. Running status monitoring

Regular pressure test: Conduct a pressure test on the check valve once a year to verify its sealing performance and operational flexibility; The test pressure is 1.5 times the design pressure, and the holding time is not less than 5 minutes.

Data recording: Establish a valve maintenance file to record the time, content, and replaced parts of each repair and maintenance, providing reference for subsequent maintenance.

3、 Precautions for Maintenance and Repair

1. Safe operation: Before maintenance, it is necessary to close the upstream and downstream valves and drain the medium to ensure that the system is pressure free; If the medium is flammable, explosive, or toxic, additional safety measures must be taken.

2. Component matching: When replacing seals or critical components, it is necessary to choose products with the same specifications and materials as the original ones to avoid leakage or blockage caused by incompatibility.

3. Professional training: Maintenance personnel need to undergo professional training, familiarize themselves with the structure, principle, and maintenance process of check valves, and avoid damaging the valves due to improper operation.

4. Preventive maintenance: Develop a preventive maintenance plan based on the operating characteristics of the system, regularly inspect and replace vulnerable parts, and extend the service life of valves.