CPVC Products - Frequently Asked Questions

Copper tube size (CTS) CPVC is designed for use in hot-and-cold-water distribution systems. CPVC systems are ideal for all potable water piping requirements in typical residential (single and multi-family), motel/hotel, mobile home, manufactured housing, light commercial, and institutional structures.

CPVC systems conforming to ASTM D2846 are rated for continuous service at 100 psi and 180 degrees F and are marked accordingly. The model codes recognize CPVC's capability to handle short-term pressure/temperature excursions beyond these levels. Therefore, CPVC is well suited for usage as T/P relief valve discharge lines, evidenced by its faultless service history over the past two decades in this application.

Iron pipe size (IPS) Schedule 40 and Schedule 80 are used for a wide variety of industrial applications.

CPVC is a very cost-effective system. The basic molecular building blocks of the CPVC molecule are chlorine, derived from salt, and ethylene, which comes from oil or natural gas. Because 2/3 of the CPVC molecule is derived from common salt, less energy content goes into making one foot of CPVC pipe than any alternative material. The price of CPVC should remain more stable than other materials in the future.

CPVC piping systems have been installed and operated since 1959, and initial installations are still performing faultlessly. CPVC piping will not fail prematurely due to corrosion, electrolysis, or scale build-up in areas where water, soil, and/or atmospheric conditions are aggressive.

CPVC pipe and fittings are available in 1/2 through 2 inch CTS (Copper Tube Size O.D.). A full range of fittings exists in all sizes. Specialty components including transition connections and chromed supply stops with CPVC solvent weld inserts have been introduced recently. Additional complementary components will naturally evolve (i.e. shower mixing valves and gate valve adapters). In applications calling for larger lines, CPVC is available in IPS sizes (sch. 40 and 80) up to 12" diameter. Transitions from CTS to IPS products can be accomplished in several easy ways.

Yes. CPVC can be installed at least 25% more quickly than copper or iron systems. Financial savings are also realized with regard to lower tool costs and insurance advantages. Considering the frequent rise and fall of the copper price structure, CPVC offers a continuing material cost advantage, often as much as a full 30% savings.

Will a CPVC system offer a financial advantage to Owners in terms of utilities expense?

Yes. The thermal conductivity of a copper system is 2500 times that of a CPVC system. The improved insulating characteristics associated with CPVC can generate substantial long-term savings for an energy conscious home-owner or tenant. CPVC will keep hot water hot for a much longer period of time than copper tubing.

A CTS CPVC system will use the same size pipe that a copper system would, providing a full bore flow system. In general an IPS CPVC system will use the same size pipe as an iron system.

What is the thermal expansion rate for CPVC, and how can I best allow for expansion and contraction when installing?

CPVC piping will expand about 4 inches per 100 feet with a 100 degree F temperature change. The fact that CPVC has higher thermal expansion than metals has led to some concern. However, laboratory testing and installation experience have demonstrated that the problems 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.

Should special considerations be taken to connect CPVC to a hot water heater?

In some instances, yes. However, these considerations are based on concerns regarding external sources of heat. The hot water from the heater will not affect the CPVC.

When connecting to a gas water hear, CPVC should not be located within 6" of the heater's flue, if the flue has no insulation. A metal nipple or flexible appliance connector should be used. This measure eliminates the potential for damage to plastic piping that might result from excessive radiant heat from the flue. If the flue is insulated, the instructions of the flue manufacturer should be followed.

When using CPVC with joints under slab, YOU MUST PRESSURE TEST THE SYSTEM BEFORE POURING THE SLAB. Also, it is wise to use 1" foam insulation pipe sleeve at changes in direction, where the pipe comes out of the slab, and at construction joints. The pipe should be evenly supported in smooth bottom trenches. The backfill should be free of rocks and debris.

Provide for a degree of movement at changes in direction due to thermal expansion.
Protect the tubing from shear forces due to minor shifts in the slab at construction joints.
Provide some protection from abuse during the construction phase for the pipe where it emerges from the slab. Longer lengths of pipe (rolled pipe) is also available for under slab installation. Follow the instructions of the manufacturer.

If the frozen section of pipe is accessible, wrap it with a cloth saturated with hot water. Keep the cloth hot by re-dipping in hot water as necessary. Be careful not to burn your hands. A second technique that is quite successful is to blow heated air directly on the area where the freeze occurred using a low wattage heater/blower such as a hair dryer. Obviously, prevention is the best way to address frozen pipe problems.

Technically, no such provision need be made when passing through wood studs. When passing through metal studs, some form of protection must be used to protect the pipe from abrasion and to prevent noise. This protection may come from plastic insulators, rubber grommets, pipe insulation, or similar devices.

Should I use metal nipples on a CPVC system when I come through the sheetrock?

In areas where there is a likelihood that stresses or impact abuse will occur, a metal nipple is recommended. Such applications as tub fillers, showerheads, and outside sillcocks are examples. However, CPVC stub-outs for closets, lavatories, and sinks are appropriate.

Should I use pipe dope, Teflon^Ž tape, or TeflonŽ paste with CPVC threaded adapters?

Teflon^Ž tape is always safe and effective with CPVC. If you wish to use a paste or pipe dope, always check with the manufacturer for a recommendation because some pastes or dopes contain solvents that may be incompatible with CPVC.

Should specific types of primers and solvent cements be used on a CPVC system? Are specific colors required?

CPVC solvent cement should always be for CPVC piping and manufactured to meet the requirements of ATM F 493. Purple primer manufactured for PVC pipe is acceptable. Faster flashing CPVC primer is available, and is recommended for cold weather installations. Orange CPVC solvent cement and purple primer are specifically required by certain code bodies to facilitate identification by plumbing inspectors. Unpigmented CPVC solvent cement and primers are available and are acceptable in various jurisdictions. Clear cement/primer provides neater finished appearance. One-step cements are now available and are fully satisfactory if the manufacturer's instructions are carefully followed. Your local plumbing inspector can provide a final answer to this question.

CPVC can easily withstand the ultraviolet exposure commonly experienced during the construction phase of a project, provided on-site inventories are turned regularly as would be anticipated. If CPVC is used in above-ground, outdoor applications, protection from ultraviolet attack can be achieved by shielding or by painting the system with an exterior-grade latex paint.

A benefit of CPVC pipe is that numerous, inexpensive choices of cutting tools are available to the installer. CPVC piping has for years been cut by fine-tooth saws. The preferred method is the circular tubing cutter, modified with a plastic cutting blade. This cutter assures a square, clean cut each time and is extermely efficient in terms of labor.

An alternative method is the ratchet cutter. Although this option is quick and easy, the pressure created while cutting the pipe could cause cracking of the pipe wall. This problem is of prime concern during cooler weather (50 degrees F or lower). For this reason, ratchet cutters should be considered only during the summer months. Keep the cutting edges of the cutter sharpened.

Several power tools have been used on major job sites where larger diameter pipe is being installed. Circular saws and portable grinders with abrasive cutting discs are two of the numerous methods being employed by contractors.

I have been told that CPVC pipe can split during installation. Why would this occur? How can these cracks be prevented?

Most cracks are initiated by rough handling. This handling can occur during shipment, while being inventoried at the wholesaler, or while on the job site. Also, fine cracks can be caused by cutting the pipe with dull or damaged ratchet cutters, or by using ratchet cutters in lower temperatures.

The vast majority of cracks occur during colder weather months. When ambient temperatures are below 50 degrees F, CPVC should be handled more carefully.

To reduce problems resulting from cracked product, several measures can be initiated:

Educate your installers. Make them aware of the potential problem and instruct them to handle CPVC in an appropriate way.
Use a saw or a circular tubing cutter with a plastic cutting blade (Rigid #151P or similar) to cut pipe to length.
Inspect pipe ends thoroughly prior to making a joint. Should a crack be evident, cut off any split portion before proceeding.
During cold weather, gripping the tubing tightly around the area to be cut for about 10 seconds prior to making the cut will warm the tubing and reduce possible problems.

Absence of the torch during construction.
Significant reduction in injuries, particularly burns, can translate to reduced workmen's compensation costs.
Reduced job site theft loss.

Yes, CPVC is extremely quiet due to the polymeric structure of the product. CPVC systems are virtually silent. Also, noise associated with water hammer is all but eliminated.

Are there other benefits associated with the polymeric makeup of CPVC systems?

Yes. Due to the CPVC polymeric structure, costly condensation concerns are eliminated, further reducing the long-term problems that one expects with a metal installation. Also, CPVC offers a potable water distribution system that eliminates the metallic taste and potential health hazards associated with metal systems.

Metal piping interests have initiated many attacks on plastic systems, under the guise of health and safety issues. Tests performed at respected universities and independent laboratories confirm that CPVC is superior to copper/lead solder systems in terms of water quality effects and is "no more toxic than wood" in a fire.

All plastics used in potable water systems must be tested regularly and certified by a similar third party certifier as meeting the strict public health requirements of ANSI/NSF 61. This testing ensures that drinking water carried by plastic pipe meets all EPA standards.