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Working with Rigid Copper Pipe

To solder rigid copper plumbing lines, you must learn a skill that is unlike other household repair skills. At first it may seem frustratingly slow. But once you get the knack, soldering will go faster than screwing together threaded pipe. Sometimes soldering is called “sweating.” Soldering works by using capillary action to flow molten solder into the fitting. Just as an ink blotter soaks up ink, a joint absorbs molten solder, making a watertight bond as strong as the pipe itself.

Eliminating Moisture - If you are adding on to existing plumbing, there may be a little water inside the pipes. This must be dried up if you are to solder a tight joint.

  • Stuff in a piece of white bread (not the crust) just upstream of the connection. It will absorb the water and dissolve when the water is turned on.
  • Buy specially made waxy capsules that plug the line while you work. Later apply heat where the capsule lodged to melt the capsule away.

1. Cut the pipe. Use a hacksaw or a tubing cutter (it makes cleaner cuts). Clamp the cutter onto the tubing, rotate a few revolutions, tighten, and rotate some more. Make hacksaw cuts in a miter box. Don’t nick the metal-—this could cause the connection to leak.

2. Remove burrs. Remove any burrs on the inside of the pipe by inserting the reaming blade of the tubing cutter and twisting. If you don’t have a tubing cutter, use a metal file.

3. Polish the pipe and fitting. Polish the outside of the pipe and the inside of the fitting with emery cloth or steel wool. This removes grease, dirt, and oxidation that could impede the flow of solder. Stop polishing when the metal is shiny. Avoid touching polished surfaces—oil from your fingers could interfere with the solder flow and cause a leak.

4. Dry-fit the pieces. Dry-fit a number of pipe pieces and fittings to make sure they are the right length. If you have difficulty pushing pieces together, the pipe may have been squeezed out of shape during cutting. Cut a new piece. Once you are satisfied, take them apart and set them on a clean surface.

5. Apply flux. Brush on a light, even coating of flux (also called soldering paste) to both surfaces. Flux retards oxidation when the copper is heated. As solder flows into the joint, the flux burns away. Use rosin- (not acid-) type flux for plumbing work.

Caution! Any gaps will leak. Be sure the joint has an even bead around its circumference to prevent leaks.

6. Protect flammable surfaces. If you’re working near framing, paper-sheathed insulation, or other flammable materials, shield them from the propane torch flame with an old cookie sheet or a piece of sheet metal.

7. Form the solder. Bend the solder so it’s easy to work with but long enough to keep your fingers away from the flame. Unwind about 10 inches of solder, straighten it, and bend 2 inches at a 60-degree angle. Light the torch. Adjust the flame until the inner (blue) cone is about 2 inches long.

8. Assemble the connection. Heat the middle of the fitting—not the joint—with the inner cone of the flame. Touch the solder to the joint. If it is hot enough, capillary action will pull solder into the joint. Remove the flame when solder drips from the pipe.

9. Wipe away excess. For a neat, professional look, lightly brush the joint with a damp rag. Take care not to burn your fingers. Most pros lay out an entire run of copper, first cutting and dry-fitting all of its components. After dry-fitting, they go back to clean, flux, and solder each joint.

10. Check for leaks. Test the system by turning the water on. If you have a leak, there is no easy solution—it cannot be fixed while water is present. Shut off the water, drain the line, disassemble the joint, and discard the old fitting. Dry the inside of the pipes. Polish the pipe end and the inside of the new fitting, apply flux, reassemble, and solder again.

11. Install pipe hangers. Copper supply lines need support at least every 6 feet. The plastic type of hanger pictured here is easy to install, helps quiet noisy pipes, and is slightly flexible so it doesn’t damage the pipes.

1. To install a brass valve, remove any heat-sensitive parts. A valve stem has rubber or plastic parts that will melt during soldering. Remove the stem with a wrench. Polish the pipe end and the inside of the fitting as you would with a copper joint.

2. Solder the joint. Fit the pieces together. (If the valve has an arrow, be sure it is pointing in the direction of water flow). Heat the body of the valve, moving the flame back and forth to heat both sides evenly. Brass requires more heating than copper. Apply solder as you would with a copper fitting.

1 .To take apart soldered joints, heat the fitting. NOTE: Shut off the water. Drain the line by opening faucets above and below the run. Light a propane torch, set it so the inner (blue) cone of the flame is about 2 inches long, and heat the fitting. Point the flame at both sides of the fitting, but not directly at the soldered joint.

2. Pull the pieces apart. While the pipe is hot, grasp the fitting and pipe with pliers, and pull the joint apart.

Caution! Once the fitting is heated, you have only a few seconds to take the joint apart. Prepare a safe place to set the torch and have two pairs of pliers within easy reach. Work carefully— the pipes are very hot.

3. Polish the pipe ends. To remove old solder, heat the pipe end with the torch and quickly wipe with a dry rag. Do this carefully—the pipe is very hot. Allow the pipe to cool and polish the end with emery cloth. Never reuse an old copper fitting—a watertight seal can only be made with a new fitting.

Working the Flexible Copper Tubing

Flexible copper tubing is pliable enough to make all but the sharpest turns. This means you don’t have to install a fitting every time you make a turn as you would with rigid pipe. In almost every case, you should connect flexible tubing to compression and flare fittings rather than soldering them. Do not use copper tubing for a gas line. Natural gas will cause the inside of the copper tube to flake, which can damage appliances.

1. Uncoil the tubing. Because flexible copper tubing is soft, always handle it gently. Uncoil tubing by straightening it out every few inches as you go. If the tubing comes in a box, grip the box and carefully pull the tubing upward.

2. Cut the tubing. Cut flexible tubing with a tubing cutter or a hacksaw. Remove any burrs on the inside of the tubing by inserting the reaming blade of the tubing cutter and twisting. Or use a metal file.

3. Bend the tubing. Bend the flexible tubing in gradual, sweeping arcs or it will surprise you by suddenly kinking and you’ll have to throw the piece away. Kinks seriously impede water flow and are almost impossible to reshape. If you need to make a fairly tight turn, use a coil-spring tubing bender like the one shown here. Slide the bender to the point you need a tight bend and, with it in place, bend the tubing. With one of these tools, it is nearly impossible to kink the tubing.

4. Polish the end. Rub the end of the tubing lightly with emery cloth to remove dirt and grease. With compression or flare fittings, you don’t need to polish as much as for a soldered joint. Join tubing by using compression fittings or flare fittings, or by soldering.

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