UV Exposure/Sun Fading Has No Practical Effect on PVC Pipe Performance, Installation and Use

The effect of sunlight on PVC pipe has been a misunderstood topic. Negative attacks by our competitors allege that exposure to sunlight causes PVC pipe’s properties to degrade so severely that the pipe becomes unsuitable for use. The attached technical brief rebuts this contention. Click here.

As with many subjects, there is a germ of truth to the allegation: it is true that UV radiation from sunlight can affect the outermost surface of PVC pipe. However, even after prolonged exposure, there is no practical effect on the pipe’s performance characteristics.

Two-Year UV Exposure Study

A two-year study has quantified the effects of sun fading on the properties of PVC pipe. The research found that exposure to UV radiation results in a change in the pipe’s surface color and a reduction in impact strength. Other properties such as tensile strength (pressure rating) and modulus of elasticity (pipe stiffness) are not adversely affected.

It is important to realize that the average impact strength after two years of exposure still remained above the level required at time of manufacture. There are no restrictions on cutting or tapping of UV-discolored PVC pipe. As well, sun faded pipe can still be installed with less care than is necessary for more vulnerable clay, concrete, or mortar-lined/epoxy-coated ductile iron alternatives.

The Bottom Line

On a practical basis, exposure to UV radiation has no performance-based effect on PVC pipe.

Regards,
	John F. Houle, P.E. Senior Technical Consultant, PVC Pipe Industry 201 E. John Carpenter Freeway, Suite 750 | Irving, TX 75062 T. 972.243.3902 | F. 972.243.3907 www.uni-bell.org