Cooper piping for water supply is available in two forms-rigid, or hard tubing, and drawn, or soft tubing. Rigid copper comes in 10-or 20-foot lengths, while soft copper comes in 60-, 100-, and 120-foot coils. You typically use rigid copper for in-house, above-concrete water-piping installations, and soft copper for below ground applications and for connecting stub-outs with faucets. Along with black steel pipe, some codes allow the use of soft copper for both natural gas and propane piping.
Rigid copper is available in Type M and Type L wall thickness. Type M, thinner than Type L, is used predominantly in residential systems. Type L is more common in commercial installations. Soft copper comes in Type L and Type K wall thicknesses--Type k is heavier. You use Type L most often aboveground, as both water and gas piping, while you use Type K soft almost exclusively for underground water piping. Type K soft copper is also used to run water service lines between public mains and private homes.
You can join rigid copper with soldered-or sweat-fitting, compression fittings, and push-fit fittings. You can join soft copper with compression and flare fittings. Threaded adapters are available for joining copper to any other threaded material, including threaded steel and CPVC plastic. Only soldered and threaded fittings can be hidden in walls, however.
Cutting Water Pipes
The methods and equipment you need to cut water pipes depend on the piping material itself. Many people cut copper and galvanized steel with hacksaw, but a tubing cutter leaves a more uniform edge. You can also cut plastic pipe with a tubing cutter, but most do-it-yourselfers reach for a hacksaw instead. The reason has less to do with the quality of the cut than with the availability of the tool. Tubing shears are probably the best cutting tool for plastic.
A clean, straight cut is also important. A tubing cutter can leave a compression ridge inside the pipe, while hacksaws leave coarse burrs. Ragged burrs protruding from a pipe's edge will eventually break off and make their way into control valves, appliances. Severe edges also create friction in the water flow, called line friction, which can reduce pressure. And finally, raised edges generate turbulence, which can eventually erode the pipe wall. To prevent these problems, ream any severe edges left by a cutting tool before you install the pipe.
To ream a copper or plastic pipe, lift the triangular reaming attachment from the top of the cutter, insert it into the end of the pipe, and give it several sharp twists. When dealing with steel pipe, you'll need a more aggressive reaming tool-one with hardened-steel cutting blades. You can rent many of these tools. If you are making only a few cuts, use a rat-tail file.