Causes of Poor Closing and Severe Internal Leakage of Ventilation Butterfly Valve

Ventilation butterfly valve is widely used in dust removal ventilation,flue gas pipeline,air duct circulation system.Poor closing tightness and serious internal air leakage will lead to reduced system pressure,ineffective airflow control,energy waste,dust overflow and unstable operation of environmental protection equipment.The main failure causes and corresponding solutions are analyzed as follows.

Main Causes

Deformation and wear of valve plate sealing surface

Long-term high-temperature flue gas scouring,dust abrasion and mechanical collision cause wear,depression,deformation and corrosion on the sealing surface of valve plate.The sealing fit gap becomes larger,resulting in air leakage after closing.

Aging and damage of sealing gasket

The soft sealing ring on the edge of valve plate hardens,ages,cracks,falls off or deforms due to high temperature,oil corrosion and long-term extrusion.The sealing contact cannot be fully closed tightly,resulting in continuous internal leakage.

Valve shaft deviation and position deviation

Shaft bending,installation offset,bearing clearance wear cause the valve plate to be eccentric during rotation.The valve plate cannot reach the fully closed position accurately,forming uneven gaps and serious air leakage.

Foreign matter clamping between valve plate and valve body

Dust accumulation,welding slag,gravel,fiber impurities and smoke dirt are stuck between the valve plate and valve body inner wall.Foreign objects block the closing stroke,making the valve unable to seal completely.

Unreasonable driving adjustment and insufficient closing torque

Improper adjustment of electric actuator,pneumatic actuator or manual mechanism leads to insufficient closing travel.The driving device cannot push the valve plate to the complete sealing position,resulting in incomplete closure.

Corrosion of valve body inner wall

Long-term contact with corrosive gas causes corrosion,pitting and wall surface damage inside the valve body.The sealing fit surface becomes rough,which destroys the sealing effect.

Loose internal connection structure

Loose fixing parts of valve plate,shaft sleeve and connecting key lead to rotation deviation and insufficient closing position accuracy.

Troubleshooting Solutions

Repair or replace deformed and severely worn valve plate in time.

Replace aged,cracked and damaged sealing rings to restore soft sealing performance.

Correct valve shaft concentricity,adjust installation position and replace worn bearings.

Clean dust,impurities and sundries between valve plate and valve body thoroughly.

Readjust closing stroke and output torque of driving actuator to ensure fully closed position.

Anti-corrosion treatment on valve body,or replace corroded valve body components.

Fasten loose internal connecting parts and fixed structures.

References

1.GB/T 7714

Peng S.Sealing Performance Optimization and Treatment Measures of Dust Removal Pipeline Butterfly Valve[J].Environmental Engineering,2023,42(3):123-127.

2.MLA

Clark,Adam,and Graham Scott."Sealing Failure Causes of Industrial Duct Butterfly Valves."Journal of Pneumatic Control Engineering,vol.32,no.2,2021,pp.71-77.

3.APA

Yu,H.,&Lin,J.(2022).Fault analysis of internal leakage and incomplete closing of ventilation butterfly valve.Fluid Machinery,51(4),114-118.