Plumbers use metal and plastic tubing to construct interior plumbing systems, including water-supply systems, drains, waste lines and vent pipes. Among the broad categories of metal and plastic exist several types of pipes, each with distinctive capabilities and characteristics. Indoor plumbing pipes vary according to the temperatures and pressures that they can handle, installation procedures, durability and cost. A comparison of the most common types of interior plumbing pipes allows you to determine the type of pipe that suits your project.
ABS is a large-diameter plastic tubing used for interior drain, waste and vent systems (DWV). To eliminate confusion with other types of plastic plumbing pipes, manufacturers produce ABS in a glossy black color. For residential use, ABS typically ranges from 1½ inches in diameter to 4 inches in diameter. Although most of a DWV plumbing system remains concealed behind walls, ABS components, such as P-traps, are available for under-sink fixtures. Plumbers use a specially formulated glue, called ABS "solvent welding compound," to joint ABS pipes and fittings. Alternatively, mechanical, clamp-on rubber fittings are suitable for some applications.
Cast-iron piping is the traditional choice for drain, waste and ventilation systems. Cast iron is thick-walled, durable and unlikely to break or bend. Pipe-fitters weld cast-iron pipes for industrial applications; residential cast-iron plumbing components connect via flexible rubber fittings. Cast iron is heavier than ABS plastic, more expensive and more difficult to work with. Cast iron eventually rusts and develops mineral deposits that contribute to blockages.
Copper Water-Supply Pipes
Despite the availability of less expensive alternatives, copper tubing remains a standard material for construction of residential water-supply systems. Copper tubing is durable and resistant to corrosion and withstands high heat. Plumbers connect copper tube and fittings via soldering with torch or mechanical, compression-type fittings. In addition to water-supply systems, plumbers occasionally apply copper tubing to refrigeration systems, fire-sprinkler systems and radiant floor–heating installations.
Cross-linked polyethylene (PEX) is a flexible, plastic tubing suitable for use in interior water-supply systems. Although PEX enjoys widespread acceptance as a viable plumbing system material, some municipalities restrict its use, and do-it-yourself plumbers must consult local building codes prior to installation. PEX is a strong, yet flexible plastic that withstands both high and low temperatures. Plumbers connect PEX with "snap and lock" compression fittings. Whereas other plumbing tubes require elaborate sets of fittings to navigate through walls, ceilings and floors, PEX's flexibility allows plumbers to snake the material around corners and turns.
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