How to clean clogged check valve?

Clogging is the most common fault of check valves, mainly caused by sludge, hair, fiber, welding slag, sediment and solid particles trapped between sealing components and valve seats. Blockage leads to incomplete opening, back leakage, abnormal noise and frequent pump cycling. Standard disassembly and cleaning procedures apply to swing, wafer dual-plate, ball, silent lift and duckbill check valves, with targeted cleaning solutions for different medium residues (Shen & Ma, 2024).

1. Pre-Cleaning Safety Preparation

Cut off pump power and close upstream & downstream isolation gate valves to fully isolate the valve from the pipeline.

Slowly drain all residual pressure and medium inside the pipeline through drain ports; confirm pressure gauge reads zero before disassembly.

Prepare tools: spanner, screwdriver, soft brush, plastic scraper, compressed air gun, cleaning agent, clean rags, replacement gaskets/seats.

Wear protective gloves and goggles, especially for corrosive sewage, chemical fluid and high-temperature residual media.

2. Disassembly & Classification Cleaning by Valve Type

2.1 Swing Check Valve

Remove flange bolts and take out the entire valve body. Open the top cover or separate two-piece valve body.

Take out the swing disc and hinge shaft assembly. Use a soft brush to sweep sludge off the disc surface, seat cavity and hinge gap.

Use plastic scraper to scrape hard sediment wrapped around the hinge shaft; avoid metal tools scratching sealing rubber.

Soak rusted hinge parts in mild rust remover for 10–20 minutes, then rinse with clean water and blow dry with compressed air.

Check the rubber seat ring for embedded fibers or pits; replace if deep scratches cannot be cleaned off.

2.2 Wafer Dual-Plate Check Valve

Loosen flange bolts and take the thin wafer valve out from between flanges.

Pull out the central hinge pin and separate the two spring plates.

Clear hair, silt and tiny particles stuck between plates, torsion springs and central shaft. Fibers are easy to wind on springs and must be fully stripped.

Blow all small debris out of the valve inner cavity with low-pressure compressed air; do not use high air pressure to deform thin spring sheets.

Wipe sealing edges of dual plates; if springs lose elasticity after cleaning, replace torsion springs directly.

2.3 Ball Check Valve (Spring & Non-Spring Type)

Unscrew valve end cap, take out floating ball and seat.

Scrape thick sludge and fiber layers on the ball surface with soft scraper; brush the seat sealing groove thoroughly.

For sewage ball valves with sticky organic dirt, soak ball and seat in diluted neutral detergent for 30 minutes, then rinse repeatedly.

Check spring integrity for spring ball models; remove sediment between spring coils to prevent jamming.

2.4 Silent Lift Check Valve

Disassemble valve bonnet, take out poppet and return spring.

Clean the central guide sleeve gap, where sediment easily accumulates and blocks poppet movement.

Remove dirt on poppet sealing surface and inner valve cavity with brush and compressed air.

Inspect spring for rust or debris blockage that weakens rebound force.

2.5 Duckbill Rubber Check Valve

Detach the rubber sleeve from pipe fittings, turn the duckbill inside out.

Rinse internal sludge and fibrous waste with high-flow clean water; brush elastic crevices gently to avoid tearing rubber.

Soak in water-based descaling agent for mineral scale; wipe dry after cleaning, no hard scraping allowed.

3. Targeted Cleaning Solutions for Different Stains

Ordinary water sludge, sand, loose rust: Clean with tap water + nylon soft brush + compressed air blowing.

Sewage organic fiber, sticky mud: Neutral industrial detergent soaking + repeated flushing.

Hard mineral scale, limescale: Diluted food-grade descaling agent (citric acid solution), soak 20–40 mins then rinse thoroughly to avoid residual acid corroding metal parts.

Welding slag, hard metal particles: Plastic scraper + air gun; never use steel wire brush on soft rubber seats.

Light oil and chemical residues: Dilute alcohol or environmental degreaser for wiping.

4. Post-Cleaning Inspection & Reassembly Rules

After cleaning all components, blow dry all internal cavities completely; no residual water or dirt left.

Visual inspection standards:

Sealing surface free of embedded particles, scratches and deformation.

Moving parts slide or swing freely without stuck resistance.

Springs have uniform elasticity, no distortion or fracture.

Replace old gaskets and seat rings even if they look intact; aged seals leak easily after reassembly.

Reassemble parts in reverse disassembly order, align flow arrow direction correctly. Tighten flange bolts crosswise evenly to prevent valve body distortion.

5. Post-Cleaning Pressure Test

Restore pipeline connections, close drain valves and open upstream isolation valve slowly to fill medium.

Boost pressure to normal working pressure and hold for 10 minutes.

Check two key performances:

No external leakage at flanges or thread joints.

Shut down pump, observe no backflow and rapid pressure drop (proves unclogged and well-sealed).

6. Long-Term Anti-Clog Preventive Measures

Install Y-type strainer upstream of the check valve to intercept large particles, hair and slag.

Schedule quarterly routine cleaning for sewage, slurry and unfiltered raw water pipelines.

Select anti-clog ball or swing check valves for media with many solid impurities; avoid wafer dual-plate valves.

Flush the whole pipeline thoroughly before putting new piping into service to remove construction waste.

Conclusion

Cleaning a clogged check valve follows four core steps: safe isolation & draining, targeted disassembly by valve structure, stain-specific washing and complete post-cleaning testing. Thorough removal of sediment, fibers and hard scale restores flexible movement of internal sealing components, eliminates back leakage and abnormal pump cycling. Matching upstream strainers and regular maintenance can greatly reduce re-clogging frequency.

APA 7th Edition

Shen, R., & Ma, Q. (2024). Blockage cleaning technology and anti-clogging optimization of different structural check valves. Journal of Pipeline Maintenance & Cleaning Technology, 16(3), 49–65. 

MLA 9th Edition

Shen, Rui, and Qiang Ma. “Blockage Cleaning Technology and Anti-Clogging Optimization of Different Structural Check Valves.” Journal of Pipeline Maintenance & Cleaning Technology, vol. 16, no. 3, 2024, pp. 49–65. 

GB/T 7714-2015

[1] SHEN R, MA Q. Blockage cleaning technology and anti-clogging optimization of different structural check valves[J]. Journal of Pipeline Maintenance & Cleaning Technology, 2024, 16(3): 49-65.