All You Need To Know About Working With Copper Pipe

March 07, 1986|By Bernard Gladstone.

Whether it is a matter of replacing a defective faucet, repairing a damaged section of pipe or adding water lines when installing a new appliance or fixture, a knowledge of how to cut, join and assemble copper pipe is often needed.

Two kinds of copper pipe are used in the home plumbing system: hard pipe in straight lengths that cannot be bent and soft pipe or tubing in coils that can be bent around obstructions to minimize the need for extra fittings. Both types are usually assembled with soldered joints, which are strong, leakproof, relatively easy to complete and, in most cases, will last almost indefinitely. For neat, watertight joints, the end of the pipe must be cut off square and the metal must be thoroughly cleaned before joints are assembled. You can use either a tubing cutter (sold in hardware stores) to cut off pipe or a fine-tooth hacksaw. With a hacksaw, it`s best to use a miter box to ensure a square cut. Then remove burrs and jagged edges with a file or abrasive paper.

After cutting, clean the outside end of the pipe where it will fit inside the fitting. Use fine steel wool or emery cloth and polish until the metal is bright all the way around. Then do the same on the inside of the fitting. Use a clean cloth to wipe away all particles from the inside of the fitting and the outside of the pipe, and avoid touching the cleaned metal with your fingers.

To ensure a good chemical bond between the solder and the copper pipe, first coat the surfaces with a noncorrosive soldering flux (sold in hardware stores). Use a small brush to apply a thin layer of the flux to the outside of the pipe and the inside of the fitting, then slide the pieces together and twist back and forth slightly to make certain the flux has been spread uniformly around on the inside.

Line up the fittings properly, then use a portable propane torch to heat the joint for soldering. Direct the heat to the heaviest part of the fitting, not on the pipe, and move the flame around all sides to heat the fitting evenly. After a minute or so, the metal should get hot enough to cause the flux to bubble and be hot enough to solder. Touch the end of the wire solder to the edge of the fitting, but do not allow the flame to melt the solder.

If the metal is hot enough, the solder will melt instantly on contact and be drawn into the joint by capillary action. If the metal is not hot enough to melt the solder instantly, take away the solder and apply more heat. If the solder melts on contact but does not draw the solder into the joint, the fitting is not hot enough. If you overheat the fitting, the solder may start to bubble or run out. If this happens your best bet is to take the joint apart and start again.

When applying solder to the joint, keep moving the end of the solder around the fitting to make certain the inside gets coated on all sides. As soon as you have a ring of solder visible on all sides, take the solder and the flame away, then use a heavy piece of rag immediately to wipe away excess solder around the outside.

When you work on existing pipes or fittings, make sure all the water is drained out before you start.