Caping Out Bad Threads Takes Some Skill

Caping threaded Pipe or fittings is a handy talent that is very helpful with repairs on threaded piping systems. Caping is necessary when a piece of threaded pipe or a nipple is decayed but the fitting it’s connected to is in good condition. However in quite a few of these situations the piping or nipple is fused into the fitting and can’t be backed using a pipe wrench.

Caping Threaded Pipe

Standard Threaded Nipple

Steps in Caping Threaded Pipe

Step #1

Ready the fitting by cutting away the defective piping leaving several inches of piping in the fitting.

Step #2

Equip your reciprocating saw with a short bi-metal cutting blade and on a slight angle begin cutting inside the pipe. You will be cutting the pipe trying to expose the threads. The reason you are cutting at slight angle is you can see how far you are away from the threads so you don’t cut right through the pipe damaging the threads. As you get closer to cutting through the pipe you can straighten out the angle cutting the pipe deeper in the fitting.

Step #3

In small diameter piping you can begin using a blunt nose chisel to knock the pipe in on itself. You are actually bending the pipe away from the threads. Once this accomplished it is usually pretty easy to back the pipe out of the fitting. If you are caping out a fitting 2” and above you may have to make two cuts close to one another knocking the piece out and bending the pipe from there.

Step #4

Clean the fitting thread with a wire brush and some WD-40 and your fitting is ready to be reused.

Questions????

  • Q. What if I don’t have an electric reciprocating saw?
  • A. You can get a jab saw that you can mount a bi-metal blade to, get one and repeat the steps above by hand. Plumbers did this stuff by hand before electrical reciprocating saws.>

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