Tips on Installing and Servicing Gate Valves

If you encounter an old-school gate valve on a job, here’s some advice to keep in mind

Tips on Installing and Servicing Gate Valves

Anthony Pacilla

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For the service technician, valves are an essential feature of a plumbing distribution system. While servicing a piece of equipment or water control, you will run into two types of valves (on residential service) — the wheel handle style gate valve and the ball valve.

The ball valve has many upsides. It is easy to turn and if exercised routinely it will clean itself through its tight sweeping motion within the valve body. But if you run into an inoperable, leaking, or ugly-looking gate valve, here are some service tips.

Old Style Gate Valves

Old style gate valves are one of the scariest valves to see as a service technician. Gate valves are very old-school and are made up of a wheel handle valve, a stem with a packing gland, a bonnet, and a disc that wedges itself into the stream of water to cut off the water supply.

It sounds like a perfect system, but the nightmare starts after you shut it off. When you shut the valve off, often the barnacles on the disc crunch their way into the disc housing and jam. Once the disc gets stuck and wedged into its resting place, it doesn’t want to come back out. You might say, “Oh well, just force it out by turning the wheel handle with a wrench or pliers,” and you would be wrong. That’s because of how the valve is designed. The wedge that is now stuck has a wheel handle and stem screwed into it just like a typical screw. When you spin the handle out in an attempt to restore flow to the system, the handle and the stem spin out of the wedge, and the wedge remains stuck in place. This is what many plumbers refer to as “dropping a gate.” You will not get that gate out, and the valve now needs to be replaced. 

When attempting to shut off a gate valve to service a device, you need to do a few things. First, explain to the customer what the possibilities are in detail so that they aren’t surprised if or when the gate drops. Second, let the customer know that if it does in fact drop, they may have to pay to have the valve replaced. This will create a clear line of understanding about who is financially responsible in the event of a broken valve. It also sets a precedent that it is an expected and probable thing so the customer won’t blame you for breaking it and follow up with the infamous, “You touched it last – you break it, you buy it.” Lastly, when you finally decide to give it a shot, shut the valve off very slowly. Do not force it at any point. If you can get the water to flow barely, then make your repair. This will require you to repair with the water partially flowing so make necessary adjustments based on site conditions to allow you to do that type of repair.

Wheel Handle Shut-Offs

After they did away with the screwed-in gate issue mentioned above, they came out with gate valves that won’t “drop.” These valves are tremendous, and older plumbers love them because you can service the valve without replacing it. It has almost an identical interior setup with packing, a stem, and a rubber washer that squishes down onto a brass seat (that’s part of the valve body) to get a good and tight seal. 

The two most essential ways to service a leaking gate valve are the two nuts. The first and smaller nut is the packing nut that holds the packing gland. The bigger nut is called the union bonnet ring. If the valve is leaking from the packing you can take the bibb screw out, take the handle off, remove the packing nut, slide it off, and repack the gland with either graphite packing (sold in a shoestring looking variety) or packing barrels (which are nice and made specifically for this repair). Or, if in a bind, you can twirl Teflon tape around itself a few times and then wrap it around as the packing gland material, grease it with plumber’s grease, and re-install the packing nut (just snug it or the nut will crack). 

If the valve doesn’t get a positive seal, you can remove the union bonnet ring and unscrew the stem, which will reveal the rubber washer held in by a bibb screw. Get yourself a flat washer variety kit, find the correct size washer, put the smooth end facing the seat and the wording facing the valve handle, and re-install.  

About the Author

Anthony Pacilla is a registered master plumber for McVehil Plumbing in Washington, Pennsylvania. He has 23 years' experience in the plumbing and HVAC trades, and has a bachelor’s in business and economics from Thiel College.



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