What Are the Common Problems with Butterfly Valves?

In your case the seat may be broken, one of the common problems. The soft rubber lining ensures a very good sealing in Epdm Lined Butterfly Valves, however due to exposure to abrasive particles, elevated temperatures or incompatible chemicals it may be subject to degradation. When the EPDM liner hardens or rips, it leaks even if the valve is wide open. This problem is far less common in metal-seated designs such as the Double Flanged Non-Rising Stem Resilient Gate Valve, where the seat is much harder and less prone to mechanical breaches.

An additional similar_damage is warpage of the disc or the misalignment of the disc. Disc in the butterfly valve spins around the flow path line; if debris lies in the pipeline or water hammer occurs, the disc can be deformed or displaced. Where as the sturdy gate in a Dual Plate Wafer Check Valve​ or the Cast Iron Wafer Check Valve will depend on spring-assisted closure opposed to full rotation, the disc of the butterfly valve is more susceptible to damage due to mechanical stress upon repeated cycling.

Actuation problems are also reported, especially in manual models. The stem may feel stiff or completely frozen for the operators. Manual Ductile Iron Non-Rising Resilient Seat Gate Valve​ employs a rising or non-rising stem with a threaded connection which allows for an even distribution of the force, butterfly valve commonly has a singe axis of rotation. Rust or sediment ring around the pivot will make it close to impossible to operate without taking it apart.

Sealing around the stem and flange joints is another issue. While items such as the Flanged Ductile Iron Silent Check Valve​ and Water Supply Wafer Check Valve​ utilize precision machined flanges to eliminate joint leaks, butterfly valves – including wafer- type models – can experience gasket failures if the bolts are not torqued evenly. Conversely, double-flanged designs like the Dual Plate Flange Type Check Valve are more stable at high systems pressure.

Finally, noise and cavitation may be performance-related. Butterfly valves in throttling service can experience similar vibrations as in lightweight designs such as Lightweight Dual Plate Wafer Check Valve, although check valves usually avoid this by simply being open or closed. Cavitation also topples internal surfaces and reduces the longevity of the service.