Thermoplastics and Sunlight: How CPVC Withstands UV Exposure

Homeowners and plumbers need to be cautious of the damaging effects UV rays can have on piping materials.

Ultraviolet light generates free radicals within thermoplastics. For thermoplastics like polypropylene (PPR), which are particularly susceptible to UV, the free radicals can begin to chemically break down the material. This leads to early deterioration of the pipe and shortens its service life.

Fortunately, this is not the case with chlorinated polyvinyl chloride (CPVC). Below, we address the impact UV light has on thermoplastic pipes and explain how FlowGuard^® CPVC is designed specifically to withstand these effects.

Effects of UV Light on Some Thermoplastic Pipes

UV light creates damaging free radicals which are extremely reactive and can cause unwanted changes within a material.

This is a problem for PPR piping because its molecular structure is especially vulnerable to free radical attack. PPR also tends to be more translucent than CPVC, meaning the UV is able to attack not only the outside surface of the pipe, but also creates free radicals and molecular damage within the pipe wall. After too much exposure, the material will disintegrate, weakening the piping walls. While effects may not be noticeable right away, microscopic damage may result in premature leaks and failures.

Conversely, UV rays and the free radicals they generate don’t have the same effect on CPVC piping. The Mechanical Engineering Department at the King Fahd University of Petroleum and Minerals conducted a study testing samples of locally manufactured CPVC pipes in harsh weather conditions.

After exposure for periods up to nine months, the results showed UV weathering had limited effects on the strength of the material. The only change was discoloration, which is actually part of the material's natural weathering process and is not detrimental to the pipe.

How FlowGuard CPVC Withstands the Effects of UV

FlowGuard CPVC does not have the same vulnerabilities as PPR. The high levels of chlorine make it naturally more resistant to free radical degradation than PPR. In addition, CPVC integrates specialized additives into the material that further protect the pipe from UV. These additives consist of carbon black and titanium dioxide, which are widely recognized as excellent UV blocking agents.

Despite FlowGuard CPVC’s resistance to UV, we recommend avoiding direct UV exposure before and during construction. This includes covering piping waiting to be installed with a non-transparent tarp or storing it in a shaded area. If possible, avoid bringing piping onsite until it is ready for installation. This will ensure that the pipe retains as much resilience as possible for the rigors of handling and installation.

Want to Learn More About FlowGuard CPVC Pipe and Fittings?

Have questions or looking for more information regarding the capabilities of FlowGuard CPVC Pipe and Fittings? Contact our team of piping systems consultants today.