Repair of butterfly valve

Butterfly valves are simple and reliable, they do not require technical maintenance during operation, and they usually fail due to improper installation. Below is a list of possible malfunctions and the procedure for repairing disc valves.

Possible malfunctions and their remedies

Malfunction	Cause	Remedy
Non-hermetic valve closure	Polymer insert damaged	Damage can occur if welding work was carried out near the butterfly valve, or if it was installed in the closed position, requiring excessive force to open. Another cause of damage may be carbonate deposits on the disk surface, typical for hot water supply systems. Remove the valve and replace the insert.
- // -	Deformed polymer insert	Deformation of the polymer insert may occur during improper installation, for example, if the valve had to be inserted between the flanges with tension, or if it was in the closed position during installation. Drain the pipeline, remove the valve, straighten the polymer insert, and reinstall it.
Unable to open (jammed)	Disk clamped by polymer insert	Drain the pipeline, loosen the flange nuts, open the butterfly valve by one quarter, and tighten the bolts.
Unable to close completely	Flow part is contaminated. Typical for butterfly valves with a vertical stem position	Drain the pipeline, remove the valve and clean the flow part.
- // -	Polymer insert (gasket) damaged	See above.
Leakage between flanges and housing	The planes of the corresponding flanges are not parallel	They should be parallel.
- // -	Additional gasket inserted	Gaskets between the valve flange and housing are not necessary. The polymer insert of the valve serves as a gasket.
- // -	Polymer insert (gasket) damaged	See above.
- // -	Bolts not tightened	No comments
Leakage from the shock absorber	Damaged or missing shock absorber seal	Drain the pipeline, remove the retaining ring that holds the shock absorber seal and replace the seal

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