If your home was built before World War II then there is a good chance that it contains threaded pipe. This piping is very hard to install and can be a nightmare to work with, but thankfully it can be replaced with a modern alternative.

To get the piping out, you will need to follow these tips and use your brute strength.

  • Turn the stop valve off and drain the water out of the pipes so that you have a dry system to work with.
  • Identify the union joint where it is possible to begin dismantling the piping.
  • Using one wrench to hold the union and one to turn the nut, begin to unthread the joint. The union will turn counter-clockwise when undoing the piping.
  • Once you have a break you can then begin to unscrew the rest of the piping.
  • If there is no accessible union then you can cut the pipe with a hacksaw. You will then be able to add a pre-threaded union to the cut pipe.
  • If the pipes are not turning then you can try using a penetrating oil to loosen the connection. Alternatively, a propane torch can be used to heat the pipe and release its grip.

Source: http://www.rooter2.com/plumbing-tools-materials-skills-removing-old-threaded-pipe/