Copper Piping: Getting The Right Length And The Right Shape

The techniques for joining copper piping and fittings are the same whether you are adding new runs or repairing damage in old ones.

The first essential step is to cut the pipe or tube perfectly straight, then clean its end of kinks or burrs and clean the mating surfaces of both pipe and fitting. Flexible and rigid copper piping can be cut with a special tool called a tube cutter, or with a hacksaw and miter box. For flexible tube, you may need a bender.

A well-made soldered sweat joint is the best for either rigid pipe or flexible tube, stronger and more leak resistant than a mechanical connection. When soldering, use a lead-free solder approved for use on plumbing piping.

The easiest solders to use are those containing an alloy of silver, tin and copper. Because of the silver content, these solders are somewhat more expensive than alloys of tin and cadmium, antimony or zinc, and they are a bit harder to find. You may need to go to a plumbing supply store rather than a home-center store. But solders containing silver are worth the extra cost and trouble because they melt at low temperatures, comparable to those of the old 50-50 (half tin, half lead) solder that in times past was the standard plumbing solder. Do not solder water piping with an acid- or rosin-core solder, or with solder containing any lead whatsoever.

Caution: Before working on plumbing with a torch, drain all water from the pipes to avoid a dangerous steam buildup. Place a heatproof pad between the pipe and surfaces that might ignite. Because of the fire hazard, avoid soldering in cramped spaces; instead of sweated joints, use flexible tube and mechanical connectors if you can.



These compression, tap-on and flare fittings go only with flexible tube; they are somewhat more expensive and less durable than sweat fittings, but they require little skill to make and are generally preferred for small jobs.

Using A Tubing Bender

Unlike rigid copper pipe, flexible tube can be bent for turns. To prevent kinks in the walls, slip a coiled-spring bender over the section, using a clockwise twisting motion. Bend the tube with your hands or form it over your knee. Overbend the tube a bit, then ease it back to the exact angle you want.

Using A Cutter

Slide the cutter onto the pipe or tube and turn the knob until the cutting wheel bites into the wall. Do not tighten the knob all the way or it may bend the wall and the joint will leak. Turn the cutter once around, retighten the knob, and continue turning and tightening until the piping is severed. Use the triangular blade attached to the cutter to ream nut the burr inside and, with a file, remove the ridge that the cutter has left on the outer surface. If you cut with a hacksaw, remove the inner burr with a round file.

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