How to Pre-Solder Copper Fittings for Plumbing

Installing shower mixers require pre-soldering preparation.

Pre-soldering copper fittings (such as shower mixers) requires preparing the fitting and cutting the copper pipe to the exact length that goes into the fitting. In short, pre-soldering is every necessary step before any soldering takes place. Note that in general, copper pipe for homes comes in either 1/2-inch or 3/4-inch diameters, so check the existing copper pipes in your home, as well as the fitting, before purchasing new pipe. Bear in mind also that preparing the copper joints (couplings) is the same process as preparing the fittings for soldering.

Things You'll Need

• Copper pipe
• Felt tip pen
• Copper couplings
• Tubing cutter
• Tape measure
• Emery cloth
• Lead-free soldering paste (flux)
• Small brush
• Lead-free solder

Instructions

1. Cut the new copper pipe to the required length (this might be the distance from the existing copper line to the new fitting). Mark the new pipe where it needs to be cut with a felt tip pen. Place the tubing cutter around the pipe and tighten the blade down onto the felt tip mark. Rotate the cutter once before tightening and rotating a second time. Repeat this until the pipe is cut.

2. Sand the inside of the inlet on the fitting where the pipe will go with emery cloth. Sand also the end of the copper pipe that will go into the fitting. Apply lead-free soldering paste (flux) with a small brush to the inside of the inlet on the fitting, as well as the sanded end of the new copper pipe (1 inch).

3. Push the copper pipe up all the way into the inlet of the fitting (usually 1/2 to 3/4 inch). The fitting is now ready for soldering. Finally, uncoil 12 inches of solder from its spool and bend the last 2 inches 90 degrees--as you continue soldering, keep bending the last 2 inches of solder for soldering the next joint. As all joints (couplings) in the new copper line are prepared the same way as described, it is always best to prepare and install all joints before any soldering takes place. Only once all joints and new pipe have been assembled, as well as the pipe pushed into the new fitting, do you turn on the propane torch and begin to solder.

Tips & Warnings

• Copper couplings come in straight, 30-, 45-, 60- and 90-degree angles to help you install pipe around corners.

References

• "Home Improvement 1-2-3"; Benjamin W. Allen, Christopher Cavanaugh; 1995