How to Solder Pipe

Soldering is the process of joining 2 metal components by the addition of a heated filler metal. The process is instrumental in joining copper plumbing pipes to form sturdy, leak-proof joints. Unlike higher-temperature forms of metal joinery like welding, soldering is a relatively safe and simple process that can be undertaken by even novice repair people. Learning how to solder pipe is mostly a matter of preparation; once you have the joint ready, the solder finishes the job quickly.


  1. 1
    Assemble the tools you'll need for soldering the pipe. Most importantly, you'll need a propane torch. This is a small propane tank with a regulator fitted on top; some have an automatic igniter, while others will require a striker to ignite the gas. You will also need lead-free solder (leaded solder can leach into your water supply, causing health problems). A tube cutter is the ideal tool for cutting copper pipes, but a hacksaw will also work. To clean the pipe, you will need some 120-grit emery cloth and a small can of tinning flux. All of these supplies can be purchased from a hardware store.
  2. 2
    Cut the pipe at the desired location. Copper tubing is soft, and is best cut with a tube cutter. To use a tube cutter, tighten the tool around the pipe and then rotate it around, lowering the blade more with each turn. After several rotations, the pipe will break off cleanly. A hacksaw will also work, but it will leave a rougher edge that will make it harder to achieve a leak-proof joint.
  3. 3
    Remove the burrs from the cut pipe. Insert the reaming attachment of the tube cutter into the freshly cut pipe and rotate it a full revolution. This will remove the metal shavings produced when cutting the pipe.
  4. 4
    Clean the pipe where it will be joined. Use the 120-grit emery cloth to clean any dirt, oil, or corrosion off the parts of the pipe that will be joined. Rub the cloth thoroughly against the surface of the pipe; the copper should be shiny when you are done. To clean the interior, wrap the emery cloth around your finger and rotate your finger around inside the pipe. Avoid touching the pipe with your bare hands after cleaning it.
  5. 5
    Apply the tinning flux to the pipe. Use a small brush to apply a thin layer of tinning flux to the pipe where it will be joined. After applying the flux, fit the pipe into its joint until it is fully seated, wiping away any excess flux. The tinning flux will acid-clean the copper as its heats, which will help the solder to flow evenly.
  6. 6
    Heat the copper joint. Turn on your propane torch, and adjust the gas regulator until the inner blue cone of your flame is about 1-1/4 inches (3.2 cm) long. The hottest point of the flame is the very tip of this cone, so hold the torch so that the cone's tip is just touching the copper joint. You do not need to move the flame around; copper conducts heat evenly and quickly, so the surrounding areas will heat sufficiently if the flame is positioned against the joint.
  7. 7
    Apply the solder to the joint. After briefly allowing the joint to heat, hold the tip of your solder against the point where the pipe meets the joint. Always hold the solder on the opposite side of the pipe as your flame; this will ensure that you are applying solder to the coldest part of the joint. The reason is simple: if the coldest part is hot enough to melt the solder, then the entire joint will be hot enough and the solder will flow easily. When you touch the solder to the joint, it will immediately melt and disappear into the joint through capillary action. A little goes a long way; be careful not to apply so much solder that it leaks out of the joint.
  8. 8
    Allow the solder to harden. Remove your flame from the pipe and allow the joint to set. The solder will be hard in less than a minute, and the joint should return to room temperature within 10 minutes.


  • You can't solder a copper pipe that has water in it. Make sure to thoroughly drain and dry the pipe before soldering.
  • When working with the propane torch, always wear safety goggles and heavy work gloves.

Things You'll Need

  • Propane torch
  • Striker (optional)
  • Lead-free solder (Typically tin (Sn) based alloy with antimony (Sb), copper (Cu), and/or Silver (Ag))
  • Tube cutter or hacksaw
  • 120-grit emery cloth
  • Tinning flux
  • Brush
  • Safety goggles
  • Heavy gloves

Article Info

Categories: Metalwork and Wire Projects | Welding