Technical maintenance of a check valve

Malfunction	Cause	Elimination
No flow	The pressure difference on the valve disc is less than the opening pressure	Increase the pressure before the check valve or reduce the pressure after it
-//-	During installation, the plug of the passage hole or the disc holder was not removed	Disassemble the check valve and remove the plug/holder
The valve does not tightly close the flow	The seat or disc is damaged by foreign bodies	Replace the check valve
-//-	A solid particle got under the disc	1. Try to wash out the particle with the flow, for this, open/close the shut-off valve near the valve several times. 2. Drain the pipeline, disassemble the valve, and remove the particle.
The check valve is knocking	A too large diameter of the valve was selected	1. Install a smaller diameter valve 2. Install a disc damper (this option is only available for some types of check valves)
-//-	- high flow turbulence - the check valve is installed too close to the centrifugal pump - vibration of the pipeline	Change the installation location of the check valve
Breakage of the check valve flange	The valve is subject to loads from connected pipelines	Unload the valve body by installing additional supports or compensators for thermal expansion
-//-	The bolts are tightened unilaterally or the corresponding flanges are not co-planar	Perform even tightening of the bolts, eliminate the non-coplanarity of the flanges