Steel pipe is generally used in the home for the installation of gas lines (although galvanized water pipe was once used, it no longer satisfies building codes). This type of steel pipe is hollow in the center and is coated black so that it can be distinguished from other pipes of similar diameter. If the installed pipe has been damaged or bent, it needs to be replaced with a new straight section and a union joint installed to fit the new pipe into place.
Things You'll Need
- Marker pen
- Tubing cutter
- Tape measure
- Union joint
- Pipe wrench
- Threading compound
- Steel coupling
- Soapy water
Turn off the gas at the gas meter. Mark the existing section of steel gas pipe on each side of the bent area. Place a tubing cutter around the pipe and tighten its blade onto one of the marks. Rotate the cutter 360 degrees. Retighten the blade and rotate the cutter a second time. Repeat these steps until the gas pipe is cut through and then cut the pipe at the second mark and remove the bent pipe section.
Measure the distance between the two existing pipe cuts and then measure the length of the body of a union joint (do not include the inlets on each end into which the gas pipes will enter). Subtract the union joint length from the measurement between the two gas pipe cuts.
Place a pipe wrench around the pipes on each side of the cutout section and turn the wrench counterclockwise to remove them from the couplings that hold them in place. Take these two pipes, as well as the calculated measurement, to a major do-it-yourself store. Have the plumbing department cut a new section of 3/4-inch gas pipe to the same length as your calculation and then have them thread both ends of the new pipe, as well as the cut ends, onto the two removed existing pipes.
Apply threading compound to both ends of the removed sections of gas pipe. Screw these pipes into the existing couplings on the gas pipeline and tighten them in place with the wrench. Thread a new steel coupling into the end of one of the gas pipes just installed. Tighten it in place with the wrench. Apply compound to both ends of the newly cut section of gas pipe and screw one end into the new steel coupling. Tighten the pipe to the coupling with the wrench. There will now be a gap in the pipeline big enough in which the union joint can be installed and where the pipes on each side of the gap will have threads.
Remove the male end of the union from the female end (the female end has the central nut attached). Screw the female end onto one of the threads on either side of the gap. Tighten it in place with the wrench. Screw the male end of the union onto the thread on the other side of the gap. Tighten it with the wrench. Thread the union's central nut onto the male end by hand and tighten it in place with the wrench.
Turn on the gas. Mix some soapy water and apply it to the steel couplings, as well as the union joint. If any bubbles are seen from the couplings/union, it indicates that gas is escaping. The pipe will need to be tightened more to the couplings/union until no more bubbles can be seen.
Tips & Warnings
- If the bent pipe section is close to the end of the gas line and is easily accessible, the pipe sections can be removed to this point by unscrewing them from the couplings, and then a new pipe section can be installed.
- Photo Credit old worked off adjustable wrench image by Kostyantyn Ivanyshen from Fotolia.com