Repair of threaded ball valve

Operation

The valve must not be operated with the ball in an intermediate position. The valve should be either fully open or fully closed.

It is not allowed to use additional levers that extend the handle for opening/closing the valve.

To prevent the ball from sticking during operation, the valve should be opened/closed periodically.

To avoid water hammer, the ball valve should be opened/closed slowly.

In case of system freezing, after draining, the ball valve should be opened/closed several times. Ice formation in the ball valve is not allowed. If the ball valve was closed during drainage, water might remain in the ball's flow part, which could freeze and cause the body to rupture.

The pressure and temperature at the valve's installation point must not exceed the working pressure. For most valve designs, operation with simultaneous maximum temperature and nominal pressure is not allowed.

It is recommended to clean the ball valve from dust and corrosion every six months and to tighten threaded connections if necessary.

Repair

Fault	Cause	Correction
Non-hermetic closure	Damaged end seal on the ball	End seal damage may be caused by lime deposits or solid particles in the working medium. Disassemble the valve and replace the ball's end seals.
-	Abrasive wear of the ball. The valve was in a partially open position, which is not allowed.	If the working medium contains solid particles that could damage the polished surface of the ball, replace the ball or valve. To prevent further failures, install a mesh filter before the valve.
Leakage at the valve stem	Damaged stem seal	Drain the pipeline, remove the handle, loosen the sealing nut, remove the retaining ring holding the seal, and the seal itself. Install a new seal, retaining ring, nut, and handle.
Cannot open/close	Stuck ball	Replace the ball. See the disassembly procedure below.

Disassembly procedure for brass threaded ball valve

To repair the ball valve, the section where it is installed must be drained, and the valve disassembled.

Remove the handle and loosen the nut holding the stem seal. Remove the retaining ring, the Teflon stem seal, and the stem itself.

The body of the brass ball valve is glued with a sealant, so some manufacturers recommend heating the connection to 200°C before disassembly.

Screw the threads into the valve couplings and secure the body in a vice on one side while turning the other side with a wrench. Remove the Teflon seal and the ball.

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