Butterfly valve leakage and solutions
Butterfly Valves are popular in industrial piping systems due to theirsimple design, compact size, quick operation, and low cost. However, leakage remains a common issue. It primarily manifests in two forms: internal leakage, where the valve doesn't seal shut, allowing fluid to pass through; and external leakage, where fluid escapes around the stem, body connections, or flange seals.
Internal Leakage
Internal leakage (the valve is not closed tightly) affects process flow directly. It leads to medium waste, pollution or safety risks.
Damage or Wear of the Sealing Surface
Cause: The medium contains solid particles,crystals,or is prone to cavitation.During valve operation,these can scratch,erode,or wear down the valve seat or the edge of the metal disc.
Solution: Regular Inspection and Replacement: Soft sealing seats wear easily. Check them regularly. Replace them quickly if needed. Select Appropriate Materials: Select the characteristics of medium. Choose seat materials that are more wear-resistant and corrosion-resistant. Examples are reinforced PTFE and metal hard seals.
Loose or Deformed Connection Between Valve Stem and Disc
Cause: The valve is used for a long time. Or the operating torque is too big. These can make connecting components (like pins or keys) between the stem and disc loose, worn or deformed. The disc cannot move to the right closed position.
Solution: Inspect and Tighten: Check these connecting parts regularly. If they are loose or worn, tighten them quickly. Or replace them. Straighten or Replace: If the disc or valve stem itself is deformed, straighten it. Or replace it completely.
Improper Operation (Insufficient Closing Torque or Over-travel)
Cause: Insufficient Torque: The valve cannot reach the fully closed position. The disc cannot contact the seat properly. Over-travel: Some valve designs have this issue. Closing beyond the dead center position creates a gap between the sealing surfaces.
Solution: Standardize Operation: Ensure the actuator (manual, electric, pneumatic) delivers adequate closing torque and brings the valve to the specified position. Adjust Limit Device: For electric or pneumatic valves, inspect and adjust the limit switch or stopper to guarantee accurate open and closed positions.
External Leakage
External leakage causes medium loss. It may also lead to serious safety accidents like fire or poisoning.
Leakage at the Valve Body and Seat Press-Fit Area
Cause: This issue primarily occurs in rubber-lined or plastic-lined butterfly valves. Excessive pipeline stress, temperature fluctuations, or manufacturing defects can create gaps between the valve body and the lining layer.
Solution: Check Pipe Supports: Ensure the pipeline is properly supported to prevent stress from being transferred to the valve. Replace the Valve: This type of leakage is typically difficult to repair on-site. Replacing the entire valve is recommended.
Leakage at the Flange Joint
Cause: The flange gasket is old, damaged or made of improper material. The connecting bolts are loose. Or the tightening force is not even.
Solution: Re-tighten the Bolts: Tighten the flange connection bolts in a diagonal crosswise order. Do it evenly. Replace Gasket: If the gasket is damaged, release the pressure. Remove the flange. Replace it with a new qualified gasket.
Leakage Between the Valve Stem and Body in Centerline Butterfly Valves
Cause: Some centerline butterfly valves have the valve stem penetrating the valve body. The O-ring or sealing gasket here is old and fails.
Solution: Replace the O-ring or seal at this position.
In summary, to prevent leakage of butterfly valve, the strategy of "prevention first, maintenance second" should be adopted. By systematically analyzing the causes of butterfly valve leakage and implementing targeted solutions and preventive measures, we can significantly improve its operational reliability, extend its service life, and ensure the safe and stable operation of the production system.