Step-by-Step: Working with Unions
To repair a damaged section of steel pipe:
1. Cut damaged steel pipe with a hacksaw. Buy threaded replacement pipes that, when screwed together with a union, are the same length as the old piece.
2. Screw replacement pieces into place with Teflon tape or pipe joint compound to seal threads.
3. Slip the union's large ring nut onto one pipe. Screw one union nut to the end of the same pipe. Screw the other union nut to the end of the other pipe end.
4. Pull the two union nuts together. Slide the ring nut back to the union nuts and hand-tighten it on the exposed threads of the nut on the other pipe. Using two pipe wrenches, give the ring nut another third-turn, while holding the opposing nut with the second wrench.