Union joints are installed in steel pipelines so that pipe sections near each side of the joint can be removed without having to first take out every pipe section from the end of the line to the location of the union. The union joint itself consists of two female threaded end nuts, with a central threaded holding nut which when tightened in place holds the end nuts together. Repairing a leaking union requires removing the union and applying more sealing tape to the threads before refitting the joint back into the pipeline.
Things You'll Need
- Pipe wrench
- Sealing tape
Turn off the water at the main shutoff valve. Place a pipe wrench around the union's central holding nut. Turn the wrench handle counter-clockwise to loosen and remove the central holding nut from the thread that it attaches to, on one of the union's end nuts. Slide the central holding nut six inches along the pipe, resting it temporarily in that position.
Place the wrench around the end nut closest to the central holding nut. Turn the wrench counter-clockwise to loosen and remove the nut from the end of the pipe. Clean around the threaded pipe end with a steel brush to remove all sealing tape. Wrap new white sealing tape twice clockwise around the threaded pipe end. Screw the end nut by hand back onto the pipe end, and tighten in place with the wrench.
Remove the other end nut from the pipe with the wrench, brush off the existing sealing tape from the pipe thread with the steel brush, and wrap new sealing tape twice clockwise around the threaded pipe end. Screw on the end nut by hand and tighten in place with the wrench.
Brush off existing sealing tape from the thread that the central holding nut attaches to, using the steel brush. Wrap sealing tape twice clockwise around the thread, and screw the central holding nut back onto the thread. Use the pipe wrench to tighten the central holding nut in place. Turn on the water supply.
Tips & Warnings
- Union joints come in different diameters to fit different diameter pipes.
- Photo Credit Hemera Technologies/AbleStock.com/Getty Images
How to Fix a Leaky Dishwasher
Is there a puddle in front of your dishwasher? Often this is a relatively easy problem to solve. At best, all you...
How to Fix Leaking Pipes
When a pipe springs a leak, the situation can get out of control fast. You don't want spraying water to wreak havoc...
How to Repair Leaky Pipes Quickly
You can stop - or at least slow down - a leak to prevent water damage until a plumber can do the...
How to Seal Pinhole Leaks in Copper Water Pipes
Even the smallest of leaks in a copper pipe can cause water damage to your home. Whether it's simply rusting the pipe...
How to Seal Leaky Drain Pipes
Even the smallest of leaks in drain pipes can cause damage and chaos in your home. Rust, rot and water damage are...
How to fix a leaking PVC or CPVC water pipe joint
PVC or CPVC piping is common in many modern houses, and occasionally a leak can develop in one of the joints. No...
How to Use a Union or Coupling to Make a Plumbing Repair
Using a coupling or a union to repair plumbing is fairly simple. But there is a difference between a coupling and a...
How to Make a Pipe Union Seal
Home ownership often leads to replacing plumbing and gas line piping at some point. Repairing leaks, especially gas leaks, is vital to...
How to Loosen PVC Pipe
PVC is used to make sewer pipes which exist in many homes. The pipe is strong and durable, and is connected together...
How to Stop a Small Leak at the Brake Line Fittings
The brake system on most vehicles consists of a master cylinder that forces hydraulic fluid through brake lines and into brake calipers...
How to Remove a CV Joint Nut
Learn how to remove lug nuts and a CV joint nut in this free auto repair video.