CSLB C-36 Plumbing ContractorService, Repair, and MaintenanceMedium
During a routine commercial plumbing inspection, you notice a constant slight drip from the stem of a gate valve on a main water supply line. The valve is fully open. What is the most appropriate immediate action to address this issue?
- AReplace the entire gate valve immediately.
- BClose the valve partially to reduce pressure.
- CTighten the packing nut on the valve stem.
- DApply pipe thread sealant to the valve stem.
Show answer & explanationAnswer & explanation
Correct answer: C. Tighten the packing nut on the valve stem.
A slight drip from the stem of a fully open gate valve indicates that the packing around the stem has loosened or worn. The first and most appropriate action is to try tightening the packing nut, which often resolves the drip without needing to replace the valve or shut off the main water supply.
Why the other options are wrong
- A. Replacing the entire valve is a last resort and unnecessary for a minor stem drip, especially when the valve is fully functional otherwise.
- B. Partially closing a gate valve is generally not recommended as it can cause turbulence and accelerate wear, and it will not stop a stem leak.
- D. Pipe thread sealant is for threaded connections, not for sealing a moving valve stem; it would not be effective here.
Gate Valve Stem Leak Repair
Addressing a minor water leak from the stem of a gate valve, typically due to loose or worn packing material.
- Common for older gate valves
- Symptom: constant drip from stem
- First fix: tighten packing nut
- If tightening fails, replace packing or valve
Memory trick: Stem drip? Tighten the nut, don't fuss, it's a quick fix!