Today's plastic-based materials enable pipe manufacturers to provide the plumbing industry with products that are rugged yet light in weight, easy to use, and cost effective. Not only for standard cold water applications anymore, these new materials can also withstand high pressures and high heat.
"The selection of materials and products has continued to expand, especially during the past few years," offered Randy Knapp, director of engineering at the Building and Construction Division of the Plastics Pipe Institute, Inc. (PPI). "We've seen growing demand not only for industry standard-bearer cross-linked polyethylene that we all know as PEX, but also for piping for residential and commercial systems in larger sizes to replace traditionally metallic systems."
According to Knapp and PPI, which is a trade association representing all segments of the plastic pipe industry, the products now being favored instead of those made from traditional metals, are PE-RT, PP, PEX and CPVC.
"There is a lot of momentum to use high-performance plastic materials in commercial water and industrial systems that require corrosion resistance and reliability,” Knapp said. “Joining is done with either mechanical fittings or by heat fusion making these systems incredibly reliable and easy to install."
Following are some examples of different types of plastic piping and their attributes.
Polyethyelene - Raised Temperature (PE-RT)
According to PPI, this material has been used for many years in applications such as hot and cold water potable systems and underfloor heating. New developments in the processing the material have made it possible for the resin to be used to make large diameter solid wall pipe and pipe with multiple layers. Sections of this pipe can also be heat fused together for a leak-free line, and provide a high temperature performance and corrosion resistance.
PE-RT is available with long-term temperature resistance ranging from well below -20°F to 180°F, and in diameters from 3/8 to 4 inches.
Available in diameters from ½ to 24 inches in both rigid and flexible lengths, the polypropylene material is known for its chemical resistance. It is now widely used in commercial plumbing applications as well as industrial piping and compressed air systems, providing a good insulation factor, which retains heat and reduces energy use. The pipe can be heat fused in diameters up to 24 inches with a full range of molded fittings available.
Flexible Cross-linked Polyethylene (PEX )
According to PPI, PEX pipe continues to gain in popularity as a product that satisfies the needs of homeowners, builders, and plumbers by providing long-term performance, and making installations more labor and cost efficient. PEX is the material of choice for radiant heating systems and is quickly replacing copper for residential potable water plumbing. Other applications of PEX include AWWA municipal water service; snow and ice melt systems; turf conditioning; residential fire sprinklers; and geothermal systems. Typically found in sizes from 3/8 to 3 inches in diameter, PEX pipe comes in straight lengths or coils and is made from proven high-performance materials.
The new edition of the “Residential PEX Water Supply Plumbing Systems Design Guide” is now available online. The guide, which includes expanded information on green construction codes, can help homeowners, designers, builders, plumbers and architects plan, understand and apply the features and benefits of a PEX pipe residential water system.
The completely updated 144-page guide includes comprehensive design concepts and installation guidelines for the proper use of PEX pipe systems. The “Residential PEX Design Guide” project was a collaborative effort between the PPI, the Home Innovation Research Labs, the International Code Council (ICC), and the Plastic Pipe and Fittings Association (PPFA).
Chlorinated Poly Vinyl Chloride (CPVC)
CPVC offers a more rigid piping system that meets the requirements of ASTM Class 23447 as defined in ASTM Specification D1784 and used for potable water distribution, corrosive fluid handling in industry, and fire suppression systems.
CPVC pipe for potable water distribution systems is manufactured by extrusion in sizes ¼ through 16 inches. It is also in available in coils for small diameters of between ½ to 1 inches.
CPVC piping, which is suitable for hot and cold water distribution, has a 400 psi pressure rating at room temperature, and a 100 psi pressure rating at 180°F. CPVC systems offer solvent welded joints, providing fast and easy installation.
According to PPI, PE-RT, PP, PEX and CPVC piping for potable hot and cold water distribution systems are recognized in all model plumbing codes.