Maintenance and repair of stop valve
Maintenance
Maintenance is only necessary for globe valves with stems sealed by replaceable rings, as the sealing material wears out during use. Maintenance of such globe valves involves periodic inspection to detect leaks along the stem, and the frequency of inspection is determined individually based on the frequency of leaks.
Leaks can be corrected by tightening or replacing the seals. The stem of such a globe valve should be periodically lubricated to ensure smooth operation and prevent corrosion.
Globe valves with bronze diaphragms and bellows stem seals do not require periodic maintenance, but due to the limited life of the diaphragm and bellows, their condition should be visually inspected periodically.
Regardless of the type of stem seal, to prevent the globe valve element from sticking to the seat, the valve should be opened/closed at least once every six months, rotating the valve element several times from fully open to fully closed position.
Remember! Globe valves are not intended for throttling flow - they are shut-off valves, and during operation the valve element should be in either fully open or fully closed position.
Possible malfunctions and repair sequence
| Malfunction | Cause | Repair |
|---|---|---|
| The valve does not completely shut off the flow | The gasket or valve is damaged | 1. Drain the pipeline. 2. Close the valve. 3. Unscrew the valve cover (faucet stem). If the cover cannot be unscrewed, it can be heated with a torch or soldering lamp. Brass valves are usually easier to disassemble than cast iron ones. 4. Replace the gasket or valve. Caution! The gasket should not protrude beyond the plane of the valve disc. Otherwise, the valve in the open position may make noise. |
| -//- | The stem is broken | Replace the stem or the entire faucet stem. Refer to the replacement sequence above. |
| -//- | Dirt got under the valve disc | Open and close several times to flush out the dirt under the valve disc with the flow. |
| The valve is buzzing | The valve disc gasket is worn out | The valve disc gasket should be replaced. Refer to the replacement sequence above. |
| Leakage along the stem | The stem seal or packing has worn out | Option 1. Close the valve and tighten the stem packing gland (nut on the stem). Caution! Over-tightening the gland may lock the valve stem. Option 2. Replace the stem seal after draining the pipeline. To do this, unscrew the packing nut, remove the remnants of the old seal with tweezers or a needle, and install a new packing ring or seal. The seal should not be too much, leaving a few turns of thread for installing the packing gland. Rope braided with graphite grease is used for sealing. |
| -//- | The stem is worn at the sealing point | Replace the stem or the entire faucet stem. Refer to the replacement sequence above. |
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