How to Replace a Soldered Wall Pipe That Leads to a Sink Trap

The trap is the curved section of pipe that is underneath a sink, leading away from the sink drain and leading to a horizontal section of pipe that connects to a stub-out on the wall. Normally, the different sections of the sink's drain plumbing connect to each other through slip nuts, allowing you to easily dismantle them for repairs or replacement. You may, however, find that the horizontal pipe is soldered to the stub-out. In this case, use alternate means to remove and replace the pipe.

Propane torch
Hammer
Pipe wrench
Tape measure
Replacement pipe
Plastic washer
Slip nut

Instructions

- 1
  Light the propane torch and aim it towards the joint where the horizontal drain pipe underneath the sink connects to the wall stub out. Keep the torch moving around the perimeter of the joint, to un-solder the connection.
- 2
  Tap the joint gently with a hammer, to loosen it. If the joint does not come loose, grip the horizontal drain pipe with a pipe wrench while you heat the joint with the torch. Slowly twist the pipe counter-clockwise, and pull it away from the stub-out.
- 3
  Unscrew the slip nut, using the pipe wrench if necessary, that connects the other end of the pipe to the sink's trap. Remove the pipe.
- 4
  Allow the stub-out to cool down.
- 5
  Measure the distance between the threads on the stub-out and the trap, using a tape measure, to be sure you have a replacement pipe of the right length.
- 6
  Place a plastic washer on the end of the replacement pipe, and a slip nut. Connect the pipe to the stub-out, tightening the slip nut with your hand. Finish tightening the slip nut with the pipe wrench, so that it is secure and snug.
- 7
  Place a plastic washer on the other end of the new pipe, and connect it to the trap with a slip nut. Tighten the slip nut by hand, followed by tightening it with the pipe wrench.

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Plumbing