CPVC Piping and UV Resistance Properties

A question piping specifiers often ask is how does CPVC fare in the presence of high intensity solar radiation and prolonged sunlight exposure coupled with temperatures as high as 50° C in summer? They want to know how using a thermoplastic material makes sense in such punishing conditions.

Fortunately, King Fahd University of Petroleum & Minerals conducted a landmark study in 2013 that examined the question of premature weathering from UV rays in detail, and the results should be encouraging. A key finding of the study, after both natural and artificially accelerated weathering testing, was that CPVC’s physical and mechanical properties stand up exceptionally well to UV exposure. The samples involved were locally manufactured 4-inch Schedule 80 CPVC pipes and were exposed for periods ranging from two weeks to 18 months at locations in Dhahran, Saudi Arabia.

Test Findings Reveal CPVC Stands Up Well to UV Exposures

Researchers found clear UV resistance as it relates to CPVC’s critical pressure-bearing capabilities (fracture strength, tensile strength and modulus of elasticity). UV rays and the free radicals they generate don’t have the same damaging effects on the piping walls of FlowGuard^® CPVC as they do on PP-R, for example.

FlowGuard CPVC is formulated with specialized UV blocking agents such as carbon black and titanium dioxide in amounts sufficient to withstand the normal exposures that occur before installation. The carbon black and titanium dioxide protect that integrity, keeping the pipe’s pressure rating, and other physical properties intact.

Gloss loss and discoloration can be a common occurrence, the study found, but that is purely superficial and not detrimental to pipe integrity in any way. An approach that is sometimes recommended as an extra precaution for external installations is painting the pipe.

It is very important to cover piping waiting to be installed with a non-transparent tarp or keep it shaded until it is imminently ready for installation. There is no practical reason for CPVC pipe to be overexposed to sunlight when it is so easy to protect it.

If you have any questions about FlowGuard CPVC pipe and the appropriate practices, check with your FlowGuard technical representative for guidance.