Advantages and Risks of CPVC Piping

When installing a new sprinkler system, property owners and sprinkler designers must sometimes choose between CPVC and black steel pipe.  Chlorinated polyvinyl chloride (CPVC) has been used for indoor piping since the 1960s and provides many advantages over other materials.  It is ductile, lightweight, and inexpensive, and its resistance to corrosion makes it well suited for transporting water.  Since fractures in the pipe can lead to massive property damage due to leaks and flooding, property owners must weigh the convenience and cost savings of a CPVC system against the risks and take extra precautions during the installation.

CPVC is a popular alternative to steel piping in fire protection systems, in particular for residential projects.  Contractors like it for its ease of installation.  Pipes can be cut with simple hand tools and joined with solvent cement rather than with welded or threaded couplings; they can also be mounted by only two workers without any special machinery.  Since diameters as small as ¾” are permitted for CPVC piping, the material is ideally suited for fitting into tight spaces such as inside walls.  In addition to the convenience and reduction in material and labour costs, it boasts some advantages for fire protection: CPVC has a lower frictional loss than black steel (with a C factor of 150 instead of 120), and is good at withstanding a fire due to its high melting point and high flame and smoke resistance.

However, there are many risks associated with CPVC piping, particularly if it is poorly installed or contaminated by other substances.  Recently, a series of lawsuits worth billions of dollars in total over failures in CPVC piping in condominiums and apartment complexes has thrown the status of CPVC sprinkler systems as durable, dependable money-savers into question.  The future of CPVC in fire protection is beyond the scope of this article, but research is underway to determine what caused this rash of accidents and whether CPVC is less reliable than widely believed, with one study estimating that as many as 80% of failures were caused by defects in the material itself rather than installation errors.  Some of the other common causes of piping failures include improper system engineering (such as not providing for linear thermal expansion), improper storage and handling, and contamination.

Installation Guidelines

In order to reduce the risk of failure, the sprinkler contractor should take the following precautions:

Follow the CPVC manufacturer’s guide carefully. Warnings are often not listed on the materials themselves.  Every manufacturer of CPVC pipes and fittings includes a manual with detailed instructions on how to install and care for every element of the system.

Hire trained installers. Many workers are unaware of the specific challenges posed by CPVC.  This can lead to errors made from ignorance or from carelessness, such as contamination or too much or too little cement.  Installers should be trained by an authorized representative of the manufacturer.

Take precautions to not expose CPVC to incompatible substances. Anything from traces of standard cleaning agents to common electrical wiring that brushes against the surface can degrade the pipe.  Solvents, cements, caulks, cutting oils, sealants, and thread pastes must be listed as compatible with CPVC by the manufacturer.  When combining metallic pipes and fittings with CPVC products in a system, the cutting oil should be removed prior to assembly.  In addition, CPVC products should not be stored in containers with metal products, as they may become damaged with packing oils.  Care must also be taken not to handle CPVC with gloves contaminated by oils or other incompatible materials.

Protect material from heat and ultraviolet radiation. When CPVC is exposed to the direct sunlight for prolonged periods, it can lose some of its impact resistance. If the material must be stored outside, it should be covered with an opaque and well ventilated tarp to limit degradation from heat and UV rays.

Take extra precautions for solvent cementing in cold weather.  Low temperatures can alter the physical properties of the pipes and fittings or interfere with the joining process by prematurely solidifying the cement.  In addition, ice or snow that comes into contact with the joining surfaces can melt and contaminate the sealant with water. To prevent adverse effects from cold weather, the system should be prefabricated as much as possible in a heated workspace and have a long curing period before operation. The solvent cement should also be stored in a warm place; take special care to ensure that the cement remains fluid throughout application. Maintain the pipe and fittings at similar temperatures.  Lastly, before the solvent cement is applied, the joining surfaces should have all moisture removed and be cleaned with a softener approved for CPVC.

Hiring a consultant engineer for the partial surveillance of the installation of your CPVC sprinkler system is a cost-effective way to ensure that the proper guidelines are being followed. Feel free to contact us for more information on this topic or to hear more about our fire protection construction surveillance services.

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