Chlorinated polyvinyl chloride pipe, more commonly known as “CPVC pipe,” is a plumbing material made of highly durable thermopastic. It is the most commonly used piping in building construction in most parts of the world, outpacing ordinary polyvinyl and metal and copper alternatives. Builders often prefer it because it is very durable, resists corrosion, and has very high temperature thresholds. This makes it safe for supplying water, gas, and oil, and it can also mean energy savings for homeowners and businesses. The biggest drawbacks usually have to do with cracking, and some people also complain that drinking water carried through these pipes has a somewhat plastic taste, particularly when the pipes are new.
How They're Made
These sorts of pipes often look like they’re made of ordinary plastic, but in most cases their manufacturing is somewhat complicated. Chemists usually begin with the polymerization of the vinyl chloride monomer, which is a molecule that forms the basis of many plastics. Through a series of reactions they then use thermal energy or ultraviolet rays to decompose the chlorine ions, which can displace hydrogen molecules.
The end result is a material that is durable and tough. From the outside it looks a lot like regular polyvinyl chloride pipe, or PVC pipe, and it shares many of that precursor’s traits when it comes to malleability and general usefulness. It is stronger and more resistant to leaks and energy loss, however. PVC was the industry standard in most places until the mid-1980s, when the CPVC alternative became more widely produced and accepted. Installation is safer and faster, requiring only a special solvent cement as opposed to the torch and solder that are usually required for metal piping. CPVC options generally last longer, too, and tend to be less susceptible to failures.
One of the biggest benefits of CPVC piping is its ability to tolerate heat. It is generally capable of withstanding corrosive water temperatures between 70°F and 90°F higher than its PVC counterparts, which makes it a good choice for carrying hot water and industrial liquids alike. For hot and cold water applications, it is typically rated at 100 pound per square inch (psi) at 180°F and 400 psi at room temperature. It is also fire resistant and will not burn without a flame source, making it suitable for fire suppression systems in light hazard and residential settings.
Chemical Corrosion Resistance
CPVC is also generally non-toxic, which means that it won’t leach chemicals or corrosives even if they’ve been sitting in the pipe for some time. It’s immune to galvanic corrosion and resists scale build up, which is important where water purity is concerned. It is also resistant to chemicals and durable against their residues. Being plastic, it is not subject to electrolysis, the process through which water breaks down into oxygen and hydrogen gas.
Homeowners and businesses often like this sort of piping because it can sometimes save money on heating and cooling costs, at least where liquid temperatures are concerned. It has pretty good insulation, which means that it keeps hot water hot and, conversely, cold water cold. Gasoline and oil often flow really well through these sorts of pipes, too, which can promote greater efficiency and in some cases means that building owners will use less.
There are concerns with the use of this piping, however. Some people who receive drinking water through CPVC pipes complain of a plastic taste in the water. The pipe and fittings are also subject to cracking if they’re dropped, and they can sometimes warp or break if a house’s foundation shifts dramatically or, as is more common in some places, during earthquakes. Despite their great resistance to temperature shifts internally, they can sometimes expand with temperature change externally. Freezing conditions can sometimes mean that these pipes will burst, for instance, which can create a major problem. There have been some documented cases of bacteria growing inside the pipe as well, often in cases where the pipes are rarely used.