Repair of check valve

The design of check valves is simple and reliable, so they rarely fail if operating parameters are followed.

However, to ensure proper functioning, it is periodically recommended to check the check valves for tightness in blocking the flow. For this, the section of the pipeline under pressure to the valve's inlet pipe is shut off and drained. Attention is paid to the pressure gauges installed before and after the check valve. If the pressure on the section after the valve's outlet pipe remains unchanged while the inlet pressure drops, this indicates that the valve has hermetically blocked the flow. If the pressure drops on both gauges, the check valve is not preventing reverse flow.

If reverse flow through the valve is detected during inspection, it should be removed. The most likely cause of failure is the clogging of the flow passage by sludge, which can be eliminated by simple cleaning.

Possible malfunctions and methods of elimination

Malfunction	Cause	Solution
No flow	The pressure difference on the valve disc is less than the opening pressure	Increase the pressure before the check valve or decrease the pressure after it
-//-	During installation, the passage hole plug or disc retainer was not removed	Remove the check valve and take out the plug/retainer
The valve does not hermetically block the flow	The seat or disc is damaged	Replace the check valve
-//-	A solid particle got under the disc	1. Try to flush the particle by opening/closing the shut-off valve near the check valve several times. 2. Drain the pipeline, remove the valve, and take out the particle.
The check valve is noisy	The valve diameter is too large	1. Install a smaller valve 2. Install a disc damper (this option is available for some types of check valves)
-//-	- high flow turbulence - check valve is installed too close to the pump - pipeline vibration	Change the installation location of the check valve
Flange of the check valve is broken	The valve is subjected to loads from the connected pipelines	Unload the valve body by installing additional supports or thermal expansion compensators
-//-	Bolts are tightened unevenly or the corresponding flanges are misaligned	Tighten the bolts evenly, correct the flange misalignment