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In the early days of American plumbing, pipes were made of lead sheets hammered into shape around a pole. Back then lead was usually called by the Latin name "plumbum," and the pipes were "plumbing." The term "plumbing" is still with us, but the lead pipes have been replaced by galvanized steel, brass, copper or plastic pipes.

Many do-it-yourselfers find it difficult to work with metal pipe. Plastic pipe, however, is an ideal material for the home handyman. It's lightweight, easy to handle and less expensive than metal pipe. You don't need special tools to work with it.Plastic pipe has a number of advantages over metal pipes. It will not rust or corrode and it's chemically inert, so it will not collect mineral deposits. The smooth interior walls allow water to flow readily, making clogs less likely. It's weather resistant, so it can be used outdoors.

It can be joined to steel or copper pipes (using special transition fittings) without the threat of galvanic action (an electro-chemical reaction between two dissimilar metals that causes corrosion).

There are some drawbacks to using plastic pipe. It cannot be used in supply systems where the water temperature exceeds 180 degrees or with water pressures more than 100 pounds per square inch.

These are not major obstacles, however. The hot water temperature can be regulated by setting the temperature-pressure relief valve on the hot water heater to 140 degrees.

Most water systems supply water at around 40 pounds per square inch. so pressures of 100 pounds per square inch are unusual. Still it is possible for overpressures to occur when the washing machine or dishwasher suddenly closes a supply valve. This overpressure, or water hammer, can be controlled by installing hammer arrestors.

Even so, some local plumbing codes still prohibit the use of some types of plastic pipe in systems. Be sure to consult a building inspector before starting any project.

There are four types of plastic piping material available; they are designated by their chemical composition, which is often hard to pronounce. It's easier to use the initials: CPVC, PVC, ABS and PB.

CPVC, chlorinated-poly-vinyl-chloride, is the most useful. It is chemically engineered (by adding an extra chlorine atom to the vinyl-chloride molecule) to withstand 180 degree temperatures and 100 pounds per square inch pressures. It is a rigid, cream-colored (some manufacturers offer other colors so you can color-code the hot and cold supply lines) pipe available in 10-foot lengths and in 3/8-, 1/2-, 3/4- and 1-inch diameters (all piping diameters are interior diameters). This is an ideal choice for hot and cold supply pipes.

PVC, or poly-vinyl-chloride, is similar in chemical composition to CPVC but without the extra chlorine atom PVC is not able to withstand hot water temperatures. You can use it for cold water lines, but there's always the danger that you'll mistake it for a length of CPVC and slip it into a hot water line. It's a good choice for drain and vent systems and for drain traps. It's available in 10- and 20-foot lengths - some dealers even sell it by the linear foot - and in diameters from 1/2 to 4 inches.

ABS, or acrylonitrile-butadiene-styrene, was the first plastic pipe approved for home use. It is used for drain and vent systems. It is available in the same lengths and sizes as PVC pipe.

Unlike the three other types of plastic pipe, PB, or poly-butylene, is flexible. That means that it can bend easily around corners; it therefore requires fewer fittings and joints. It is heat-resistant so it can be used for hot and cold supply lines. PB is sold in 25-foot and 100-foot coils and is also sold by the linear foot.

Most plastic pipe is pieced together using straight sections and fittings. The fittings may be either elbows, couplings, reducers or T-fittings. The sections and fittings are bonded with a special solvent that is applied to both pieces. The solvent is formulated for specific plastics, so PVC solvent is used to bond PVC pipe, and ABS solvent bonds ABS pipe. The solvents are not interchangeable.

In some cases the bonding is a two-step process. First a primer is brushed on the pipe, then the solvent. Working time is limited, usually about 30 seconds. It's important then to work accurately and quickly, because the pieces cannot be disconnected once they are joined. If the fitting is incorrect, you have no choice but to saw it off and try again with a new fitting.