Plastic Pipe Misconceptions That Can Cause Job Site Problems

According to responses to a quiz created by FlowGuard Gold Pipe and Fittings, the manufacturer found many plumbers who aren’t fully knowledgeable about certain issues pertaining to pipe materials like CPVC and PEX

Plastic Pipe Misconceptions That Can Cause Job Site Problems

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FlowGuard Gold Pipe and Fittings recently produced a quiz to gauge plumbers’ knowledge of plumbing material characteristics and the right tools to use with different plastic plumbing materials.

After more than 1,500 individuals took the quiz, two issues stood out as areas where many plumbers are operating on outdated information or failing to fully account for important differences in material characteristics, both of which could lead to unwanted problems on the job.

The Right Tool for the Job

One of the first things you learn when entering any trade is to always use the right tool for a particular job. According to the FlowGuard quiz, that isn’t always happening. When it comes to cutting pipe, it’s not only a matter of matching the right tool to the right material but also, in the case of CPVC, to the age of the material you’re working with. Over 60% of the quiz respondents didn’t know the correct tool for cutting into an existing CPVC system.

With new CPVC, ratchet-style cutters are recommended because the material is relatively flexible. But as CPVC ages, it becomes more rigid. The pressure-bearing capability of the material actually increases with age, contradicting the perception among some plumbers that CPVC that appears brittle is weak or compromised. It isn’t, but it does require special handling and a different tool for cutting. If you use ratchet-style cutters on older CPVC, you may end up with cracking, which can add time to a job. Whenever working with already-installed CPVC, use C-style cutters or a fine-tooth saw.

While PEX doesn’t require a different cutting tool when working with new versus installed pipe, the quiz revealed that there was still a misunderstanding about the right tool to use. Almost 20% of plumbers said they wouldn’t use a ratchet-style cutter to cut into existing PEX. In fact, ratchet-style cutters can be used.

Always think about the material characteristics before you make a cut. Ratchet-style cutters are recommended for flexible tubing such as new CPVC, new PEX, and for servicing PEX. C-style cutters are recommended for more rigid materials, such as older CPVC or copper.

Recognizing Service Issues

Not every situation a service plumber faces is as straightforward as selecting the right tool. Plumbers are often required to diagnose causes of failure and take appropriate corrective action. Knowledge of plumbing material characteristics can help you make the right call. The FlowGuard quiz revealed a few opportunities for education. 

A high percentage of plumbers attributed a PEX chlorine failure to UV light. UV light can indeed contribute to chlorine-related failures, but it doesn’t actually cause the failure. What it does is act as a catalyst for the oxidation process that consumes the chlorine inhibitors that protect the pipe from chlorine-induced oxidation. As these chlorine inhibitors get consumed, piping is left vulnerable to attack from chlorine in the water.

This may seem like a technicality, but if you simply replace the failed pipe thinking the problem was UV light exposure, you could be ignoring a broader issue that might require a repipe. If that pipe was unable to handle water conditions in the home, it’s likely other pipes in the home may be experiencing similar degradation but haven’t yet begun to leak.

Another education example involved making a call on whether “brittle” CPVC needed to be replaced. A majority of plumbers said “yes” when, in fact, older CPVC has excellent pressure-bearing capability and can remain in service. In this case, repiping based on the age or rigidity of the material would be unnecessary. 

While many plumbing practices haven’t changed significantly over the years, materials, water treatment practices and other factors that can affect residential plumbing continue to evolve. The FlowGuard quiz demonstrates the importance of material manufacturers providing comprehensive training and education and plumbers regularly seeking out these materials to prevent avoidable problems. To help plumbers access training and education on servicing CPVC, there is a new information hub on the FlowGuard Gold Pipe and Fittings website.

About the Author

Jonathan Simon is the North American residential plumbing manager for Lubrizol Advanced Materials Inc., the parent company for FlowGuard Gold Pipe and Fittings. For 60 years, FlowGuard Gold Pipe and Fittings has provided reliable hot and cold water plumbing systems to residential and commercial buildings. For more information, visit


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