OPUS

Domestic Water: CPVC Pipe

Domestic hot and cold water systems generally convey potable hot and cold water used for...
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Chlorinated Polyvinyl Chloride (CPVC) is a thermoplastic pipe and fitting system made with CPVC...
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Benefit of Material to Systems Application

While copper tubing had been the predominant material used in domestic hot and cold water systems for several decades, Chlorinated Poly Vinyl Chloride (CPVC) has gained a sizeable share of the market due to its lower cost, easier installation, resistance to corrosion and abrasion, high impact strength, and light weight. CPVC piping materials have a smooth bore which improves flow.  CPVC pipe also reduces water noise. CPVC is particularly useful as a corrosion-resistant alternative to copper in situations where aggressive or acidic water or soil is prevalent (for example, pH less than 7).

System Application and Material Usage

CPVC piping for potable hot and cold water distribution systems is recognized in all model plumbing codes, but always check with local building departments to ensure its compliance. A few jurisdictions have specific restrictions on the use of CPVC. All plumbing codes specify the allowable materials used for water distribution and require the use of piping having a 100 psi @ 180°F rating for the hot water portion of the system.

CTS (copper tube size) dimension CPVC pipe for plumbing systems is manufactured in sizes ½ inch through 2 inch. The CTS plumbing products are made to copper tube outside diameter dimensions, in accordance with ASTM D2846 specifications, and have an SDR (Standard Dimension Ratio) 11 wall thickness. SDR dimensions means that the pipe wall thickness is proportional to the outside pipe diameter and that all sizes of pipe are rated for the same pressure.

CTS fittings are also made to ASTM D2846 standards.  The pressure ratings of the CTS SDR 11 systems are 400 psi at 73°F and 100 psi at 180°F. CPVC plumbing pipe is sold in both straight lengths and (in small diameters) coils. These systems are hydrostatically tested at 150 psi at 210°F for at least 48 hours to assure integrity at those conditions, which may develop in the event that the water heater controls malfunction. Thus, such materials are suitable for hot water distribution where water heaters are installed with relief valves set at 150 psi at 210°F.

IPS (iron pipe size) dimension CPVC pipe for plumbing systems is manufactured in sizes ¼ inch through 24 inch. For potable water the typical sizes are 2 ½ inch through 8 inches.  The IPS piping products are made to iron pipe outside diameter dimensions, in accordance with ASTM F441 specification, and have a Schedule 80 wall thickness.  IPS fittings are Schedule 80, meeting the requirements of ASTM F437 (threaded) or ASTM F439 (socket).  The pressure rating of the IPS Schedule 80 system reduces as the diameter increases according to the table shown below.  (Note that the pressure bearing capability also changes as the temperature changes according to the derating factors for CPVC piping systems.)

Nominal Pipe Size (in.)

Maximum Water Pressure (psi) at 73°F
2 ½420
3370
4320
6280
8250

When Schedule 80 CPVC piping is used in the hot and cold water distribution system in a commercial type building, it must be part of an engineered piping system.  CPVC water piping may be used in the ground, above ground, and in and below concrete slabs, or as water supply and distribution lines. It may be used outdoors if the pipe contains pigments to shield against ultraviolet radiation. Painting the assembly with water-based latex paint is one way to develop this protection.

Like all piping material, CPVC expands when heated and contracts when cooled. CPVC piping (regardless of pipe diameter) will expand about 1 inch per 50 feet of length when subjected to a 50°F temperature increase. Therefore, allowances must be made for this resulting movement. However, laboratory testing and installation experience have demonstrated that the practical issues are much smaller than the coefficient of thermal expansion would suggest.

The stresses developed in CPVC pipe are generally much smaller than those developed in metal pipe for equal temperature changes because of the difference in elastic modulus. Required loops for CPVC piping systems are typically smaller than those recommended by the Copper Development Association for copper systems.

Support of vertical piping should be made at every floor, with a mid-story guide if the pipe diameter is 2 inch or less.  Expansion is mainly a concern in hot water lines, although it may occur in cold water lines when the temperature at the time of the installation is very cold.

Generally, thermal expansion can be accommodated with changes in direction; however, a long straight run may require an offset or loop. Only one expansion loop, properly sized, is required in any single straight run, regardless of its total length. If more convenient, two or more smaller expansion loops, properly sized, can be utilized in a single run of pipe to accommodate the thermal movement. For above ground installations, be sure to hang pipe with smooth straps that will not restrict movement. For underslab or below ground installations, be sure backfill material will not restrict movement at the expansion loop, offset or change of direction.  

The most commonly used joining method for CPVC pipe and fittings uses a solvent-cement on the pipe end and in the tapered socket. Additional joining methods include threaded joints (Schedule 80 CPVC pipe) and flanges (most often for transition joints).

Manufacturers and Suppliers Participating in OPUS

ANVIL International

Anvil International offers a full line of domestically-produced iron fittings, steel nipples,......
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Charlotte Pipe & Foundry

Charlotte Pipe and Foundry is the only manufacturer that offers a system of cast iron, PVC......
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Embassy Group LTD

Embassy Group LTD is a 100-percent member owned, 3.2 billion dollar corporation consisting of......
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F.W. Webb Company

F.W. Webb Company is a multi-faceted distributor of plumbing and heating, HVAC and controls,......
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Ferguson

Ferguson specializes in providing PVF, Plumbing, HVAC and Related Specialty Products and......
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J.O. Galloup Company

J.O. Galloup Company is a premier distributor of commercial and industrial piping products,......
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NIBCO INC.

NIBCO Inc. is a recognized industry leader of flow control solutions to the residential and......
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Weldbend Corporation

Weldbend Corporation is a manufacturer of carbon steel welding fittings and forged steel......
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WinWholesale, Inc.

WinWholesale, Inc. is comprised of over 525 wholesale distribution locations. Along with Noland......
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Woodford Manufacturing Company

Woodford Manufacturing Company offers frost-free, backflow protected commercial, residential and......
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Applicable Joining Methods

Solvent Weld

Solvent welding, also known as solvent cementing or solvent bonding, is the process of joining...
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