Your home's gas piping system consists of various lengths of straight pipe with different fittings. Since piping threads into fittings by turning it clockwise, you cannot simply unscrew a section of pipe -- as one end loosens, the other will tighten. This is where unions come into play. They allow you to swap out a section of pipe without unscrewing the entire pipe system from the appliance to the damaged section. With just a few common tools, you can quickly make this repair yourself and possibly save hundreds of dollars by not having to call your local heating technician.
Things You'll Need
- Reciprocating saw
- Pipe wrenches
- Black pipe nipples
- Black union
- Pipe thread compound
- Gas leak detector
Turn off all appliances that utilize your natural gas system and then turn the valve at the gas meter to the "Off" position.
Cut through the section of pipe you wish to replace with your reciprocating saw. You may cut through it any place along the pipe.
Turn each piece counterclockwise with your pipe wrench to remove it. The cut you made in Step 2 allows the pipe to turn without further threading it in the opposing fitting.
Measure the length of each piece of pipe you removed. Add these lengths together; this is your total length needed.
Measure the length of the union and subtract 1-1/2 inches (3/4-inch allowance for each connection). Take the final measurement and subtract it from the measurement calculated in Step 4. This is the total length of straight pipe needed.
Divide the total length calculated in Step 5 by two. This will give you the needed length for each pipe (you will have one before the union and one after).
Wrap pipe thread compound around the male threads on each piece of pipe. Install the first piece of pipe into one of the fittings and tighten by turning clockwise. Screw one half of the union on to the other end of the piece of pipe. Screw the other piece of pipe into the other fitting and tighten. Finally, screw the other half of the union on to the end of that piece of pipe. If you measured correctly, each half of the union should butt up next to each other.
Tighten the union. Once tight, the pipe system will be sealed. Turn the valve on at the gas meter to restore gas pressure to the system.
Test for leaks around each of the new joints with gas leak detector. You should not see any bubbles forming at any of the joints.
- Plumber's Quick-reference Manual; Roger Dodge Woodson; 1995
- Timothy Gonyo; Air Flow, Inc; Milwaukee, Wisconsin