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By: FlowGuard EMEA on 26-oct-2020 1:00:00
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Putting the Pieces Together: The Truth About FlowGuard CPVC

Throughout Lubrizol’s growing reputation for the pioneering development, manufacture and processing of CPVC over the last six decades, there has at times been some misunderstanding about CPVCs strengths, what it can do and how it benefits property owners for the long term.


These misconceptions often arise when being compared with alternative materials for plumbing pipe, such as PPR, PEX or copper. And while CPVC is a chlorinated form of PVC, it has often been unfairly compared to PVC, its closest relative.  


The truth, in full, is as follows; with proper handling, storage and installation by trained professionals, FlowGuard® CPVC plumbing pipe performs water distribution to the highest standard, and is equipped to do so for decades at a time. 


What is Lubrizol CPVC?

The Lubrizol Corporation began pioneering chlorinated polyvinyl chloride (CPVC) in 1959. The main focus was to develop new materials for use in piping systems, which led to the establishment of FlowGuard Pipe and Fittings.   


The chlorination of PVC to make CPVC has led to the creation of one of the strongest, durable plastic materials for potable water available today. Its inherent heat, chemical and corrosion resistance has led to safe and reliable installations in residential and commercial properties for 60 years. 

What Makes FlowGuard CPVC?

PVC is converted into CPVC through a process of chlorination. Through this process, additional chlorine atoms are added to the molecular chain of PVC, adding a layer of security that gives CPVC its strength. This chlorination protects the PVC carbon chain from degradation, keeping the polymer intact. 

the addition of chlorine atoms to PVC to make CPVC


Degradation of polymers can occur in various ways, including fire, acid, oxidisers and UV. CPVC protects the molecular chain from all of the above, its chlorine atoms acting as back-up resources to keep the chain stable. 


CPVC’s inherent properties give pipe manufacturers and installers a healthy list of advantages:

  • Flame and smoke performance
  • Acid and oxidiser resistance
  • Biofilm resistance
  • Immunity to chlorine in drinking water
  • Design flexibility


Understanding the science behind CPVC’s core strength, allows us to address the common misconceptions about this highly versatile and reliable material.


What are the Misconceptions About CPVC?


“CPVC has the same strengths and weaknesses as PVC”


The truth about FlowGuard CPVC is that it achieves a level of strength and resistance that PVC simply cannot. 


It’s essential to know the difference between PVC and CPVC, as a transformation occurs through the chlorination process. The addition of extra chlorine atoms acts as body armor for the carbon chain of the polymer. 


For example, when an oxidiser attacks, it knocks hydrogen atoms (blue) away from the polymer’s core (grey) and causes it to split apart. The additional chlorine atoms in CPVC (red) contain additional electrons which attach to the oxidiser, leaving the carbon chain intact.  


comparison of PVC and CPVC molecular structure


For pipe installers, this means healthy flow of water in harsher environments where ordinary plastics would be prone to degradation.


“CPVC pipes and fittings are not welded, they are glued together”


The truth about FlowGuard CPVC is that it is not welded or glued, it is fused at the molecular level, creating a fundamentally inseparable bond. 


It is often considered that all pipes and fittings must undergo a welding process for a fully secure installation to take place. These types of processes are typically associated with heat welding tools or electrical machinery. CPVC is sometimes misunderstood in this area, since equipment like this is not required. 


Installers fit FlowGuard CPVC pipes using solvent cement. This substance is far from glue. CPVC is an amorphous polymer, which means it must undergo molecular entanglement for it to bond. While heat tools can achieve this, it cannot perform as well on materials with such a high natural resistance to heat. Solvent cement makes the molecular structure moldable, at which point it can bond against another CPVC surface.


“CPVC is no safer for home plumbing than PPR or PEX”


The truth about FlowGuard CPVC is that it consistently outperforms its rivals when it comes to corrosion and bacterial resistance. 


The following data from a third party study demonstrates that there is a major difference between plumbing pipes, in terms of how effectively they resist biofilm formation. 


Biofilm is the development of substances inside aqueous environments which can harbor harmful bacteria, including legionella. This table shows CPVC’s strength against legionella formation as superior to its plastic counterparts and even stainless steel:


legionella sample test in plumbing pipe materials


CPVC naturally resists biofilm formation; its chlorinated environment is not an ideal space for biofilm to attach and multiply. PPR, for example, has a textured surface which enables a faster, secure attachment, allowing biofilm to thrive.


“CPVC plumbing pipes do not last long enough”


The truth about FlowGuard CPVC is that its history in reliable plumbing installations goes back 60 years.


Many FlowGuard CPVC water distribution systems installed 60 years ago, shortly after CPVC was pioneered, are still functioning and performing well today. This has not been the case for a number of CPVC’s common market alternatives.



A material that has been publicized as a reliable alternative to CPVC in the past, is PEX. In addition to its known vulnerability to biofilm formation as illustrated above, PEX also has a history of 10 class-action lawsuits dating back to 2008, all resulting from failures from contact with drinking water.


In plumbing applications, chlorine resistance is essential. While CPVC is inherently resistant to chlorine commonly found in treated water, multi-layered composite pipe made of PEX cannot adequately transport water with chlorine levels any higher than 5ppm. This is a difficulty for plumbing installations in harsh disinfection environments.



In a study comparing the service life of CPVC with PPR, it was revealed that PPR is highly susceptible to the corrosive effects of chlorine and hypochlorous acid, which forms when drinking water is disinfected for consumption. Through a combination of oxidation, stress cracking and erosion, PPR displayed significant damage after just ten months.


comparing the effects of chlorine on PPR and CPVC


The Truth About Installing FlowGuard CPVC

While the arguments for FlowGuard CPVC’s superior strength in plumbing applications are many in number, it’s important to remember that these strengths are only valid through proper handling, storage and installation of CPVC pipes and fittings. 


In order to keep FlowGuard CPVC Pipes and Fittings performing at the optimum level, it is important that installers learn the installation process thoroughly. While it is a much faster and straightforward process than installing PPR (cutting installation time by up to 50%), it must be adhered to exactly in order for permanent molecular bonds to be formed.


See our video, How to Install FlowGuard CPVC With Solvent Cement.


Along with a thorough knowledge of installation, installers must know the correct practises for handling and storing FlowGuard CPVC, in order to maintain its maximum effectiveness. 

For example, it is better to store pipes in a relatively flat, protected area, free of sharp or jagged rocks and debris. While CPVC pipe is naturally resistant to UV, a non-transparent material will help prevent the discoloring effects of sunlight. 


Pipes should always be inspected for damage prior to installation. Small cracks can form if the CPVC pipe has been handled forcefully. If this should happen, the installer should measure 5cm from the end of the crack and recut the pipe. 


FlowGuard Pipe and Fittings also come with an in-house team of technical support specialists, the largest network of experts in the industry. They can assist with material specification, system design, installation and availability. 


Why do Misconceptions About CPVC Happen?

Such misconceptions about CPVC have, unfortunately, received widespread media coverage. The misunderstandings that have brought CPVC under fire have been spurred on by local competition, particularly in the US.  


The repiping business have been particularly outspoken against CPVC piping in domestic applications, sometimes referring to PEX as a smart alternative. While they are, as repiping specialists, required to encourage homeowners to replace their current systems with alternatives, the complete removal of a CPVC water distribution system should only take place if a thorough, professional installation has not been followed through correctly. 


As the studies show, CPVC consistently outperforms PEX and PPR in terms of contamination prevention, corrosion resistance and service life. CPVC pipes that were properly installed decades ago across the world are still in use to this day.


In Saudi Arabia, one of the most ambitious residential developments in recent history has been the National Guard housing project, consisting of over 30,000 residential villas. This project began 30 years ago and now has FlowGuard CPVC delivering clean, safe water to every building. FlowGuard Pipe and Fittings was chosen for its speed of installation and in particular, its resistance to chlorine.


Don’t be Misled: Ask for the Truth

Talk to your supplier and discuss CPVC and its alternatives. Get the facts about piping materials available in your area and their true effectiveness, and get the project completed properly the first time, entrusting your project and your customers safety to materials and installation processes that are proven.

Don’t settle for anything less than effective results that last decades. Talk to one of our technical support specialists about properly installing FlowGuard CPVC in your community.


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