How to Install a Stop Valve on Steel Pipe
If an old galvanized pipe comes out from the wall, installing a shutoff valve is usually a straightforward job; simply screw a threaded stop valve onto the pipe. If possible unscrew the supply tube at the bottom only, so it remains attached to the faucet or toilet above. If this is not possible, you may have to cut through the supply tube with a hacksaw and replace the tube after installing the valve.
Unscrew the parts up to the nipple that sticks out of the wall. Look into the pipe with a flashlight. If it is partially filled with mineral deposits, replacing it will increase the faucet's (or toilet's) water pressure. Some water will remain in the pipes and tubes after water has stopped flowing out the faucet, so you might want to place a bucket or a thick towel underneath.
Expect to spend about one or two hours installing the stop valve. Before you begin, shut off the water, drain the line, and place a bucket or towel below the pipe to catch debris.
What You Need
- Two pipe wrenches
- Adjustable wrench
- Hacksaw (if needed)
- New threaded stop valve for your size of pipe
- Pipe-thread tape
- Pipe nipple (if needed)
Refresher Course: Working with Steel Pipe
Before you begin the project, measure to find the pipe lengths you need. Be sure to take into account the distance the pipes will travel inside fittings and valves. Then wrap each pipe end with several windings of pipe-thread tape and use a pipe wrench to firmly tighten each pipe and fitting in order. Tighten with a tool no smaller than a 14-inch pipe wrench; a smaller tool may not have enough power.
Step 1: Shut Off Water and Remove Elbow
Shut off the water and drain the line by turning on a faucet at a lower location. Hold the steel pipe still with one pipe wrench while you remove the elbow with another wrench. If you can't budge the elbow, slip a length of 1-1/4-inch steel pipe on the wrench handle for more leverage.
Step 2: Screw on Stop Valve
Clean the pipe threads and wrap pipe-thread tape clockwise around the threads several times. Screw the stop valve onto the pipe and tighten with an adjustable wrench. (Don't crank hard with a pipe wrench or the valve might crack.)