How to Seal a Copper Pipe

Written by steve sloane
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How to Seal a Copper Pipe
Heat around the pipe end/cap area using a propane torch. (Comstock/Comstock/Getty Images)

Copper is one type of piping that is used in the installation of household water supply lines. Generally installed in 3/4- and 1/2-inch diameters, the pipe sections join to each other with couplings and melted solder. Sealing a copper pipe end is done with a fitting called an end cap. This cap looks somewhat like a shortened straight coupling, but with one end sealed off. Once fitted, the cap can be later removed to add more pipe to the existing line.

Skill level:

Things you need

  • 120-grit emery cloth
  • Circular wire brush
  • Soldering paste and brush
  • Roll of solder
  • Propane torch
  • Rag

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  1. 1

    Wrap 120-grit emery cloth around the outside end of the existing copper pipe. Turn the cloth several times until the pipe end becomes shiny. Push a circular wire brush into the end of the copper end cap, twisting it around several times.

  2. 2

    Brush a thin layer of soldering paste (known as flux) around the shiny pipe end, and the inside walls of the end cap. Push the cap fully onto the end of the pipe.

  3. 3

    Pull 8 inches of solder from its spool, and bend the last 2 inches 90 degrees. Turn on the propane torch.

  4. 4

    Heat all around the seam where the pipe enters into the end cap, using the propane torch. Touch the tip of the solder to the seam. If the pipe/cap is hot enough to make the solder melt, apply solder all around the seam. Wipe off all excess solder and flux residue from the pipe/cap seam using a rag.

Tips and warnings

  • Take time wiping away all traces of flux residue. If left, it will corrode the pipe/cap over time.
  • Make sure there is no water in the pipeline near the soldering area. If there is, the pipe/cap won't reach the required temperature to make the solder melt.

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