How to repair a failed check valve?

How check valve works?

Check valve refers to the valve that automatically opens and closes the valve plate by replying on the flow of the medium itself to prevent the backflow of the medium. The check valve is also known as cut off valve, one way valve, back pressure valve, non-return valve, back water valve, etc.

The check is working automatically, under the action of fluid pressure flowing in one direction, the valve plate opens; when the fluid flows in the opposite direction, the fluid pressure and the self-weight of the valve plate work on the plate to close it on the valve seat, thereby cut off the flow.

Why check valve failed?

① the valve disc is broken.

② the medium is flowing back.

And how to repair the failed check valve?

① Why the valve disc is broken: the reason why the check valve disc is broken is that: the pressure of the medium before and after the check valve is in a state of close to balance. The disc always beats the seat, and also for some disc with fragile material like cast iron and brass, it will be broken. The maintenance method is to replace the broken disc or use the check valve with disc of ductile material.

② the backflow of the medium cause the failure of the check valve: the reason for the backflow of the medium in the check valve is the damage of the sealing surface or the inclusion of impurities; the maintenance method is to repair the sealing surface and clean the impurities, which can prevent the backflow of the medium.