Plumbing & Heating Division

Order Now- PEX design guide for residential plumbing systems
(Prepared by the NAHB Research Center for PPI, PPFA and PATH)

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NAHB-RC Surge Pressure in Plumbing Pipe Materials

NAHB-RC: Fixture Flow Rate Comparison - Cross-Linked Polyethylene (PEX) Piping and Copper Tubing

Product Overview

Plastic pipe became a real alternative to traditional plumbing pipe with the introduction of cross-linked polyethylene in the early 1970s. Plastics have since gained an excellent reputation for reliability – some pipes have been in continuous pressure service for more than twenty-five years.

Crosslinked polyethylene (PEX), chlorinated polyvinyl chloride (CPVC), and crosslinked polyethylene-aluminum-crosslinked polyethylene (PEX-Al-PEX) are used to produce pipe and tubing for a variety of domestic and industrial hot and cold water applications. All offer the advantages of plastics, including overall durability, light weight, corrosion resistance, and flexibility. In addition, they are designed to resist the temperatures and pressures encountered in hot water systems.

PEX, CPVC, PEX-AL-PEX

PEX is very similar to polyethylene in appearance but, because of cross linking, is a thermoset material – it does not melt. It is highly flexible and easily coiled. PEX is approved in all North American model plumbing codes for hot and cold potable water distribution systems.

CPVC, in addition to its use in domestic plumbing systems, is used extensively in fire sprinkler systems. A service life of over thirty-five years, outstanding corrosion resistance, low flame spread, and low smoke emission levels make it a good choice for this service.

The PEX-AL-PEX composite capitalizes on the corrosion and chemical resistance of plastic and the pressure capacity of metal by laminating the aluminum layer between layers of plastic. The resulting tubing is non-corroding, bendable for form stability, flexible, and resists most acids, salt solutions, alkalis, fats, and oils.

Temperatures and Pressures

PEX maintains a good hydrostatic rating at 200°F and resists creep when projected to a fifty year service life. Its flexibility, while maintaining pressure, eliminates the water hammer noise of traditional plumbing systems.

Installation and Joining

Composite pipes (PEX-AL-PEX or PE-AL-PE) are used in residential and commercial plumbing and in pressure service on compressed air and compressed gas systems.

PEX, and PEX-AL-PEX tubing are typically joined with metal fittings; CPVC tubing with solvent weld fittings. All of these components are readily available and inexpensive. Plastic tubing does not require soldering or special threaded connections.

Maintenance

These systems require little on-going maintenance. The plastics are not subject to corrosion and scaling problems and their inherent flexibility and freeze-tolerance eliminates the possibility of pipe rupture.