Understanding CPVC piping within industrial process water applications. By Sinikka Freidhof and Jorge Solorio
Traditionally, engineers and procurement professionals relied largely on steel and other higher alloys for industrial piping. However, current analysis reveals that in many applications, chlorinated polyvinyl chloride (CPVC) outperforms metallic systems with regards to corrosion resistance and is therefore more cost effective due to its extended lifetime. Yielding an overall lower installation cost, less maintenance and boasting a strong performance with a wide variety of chemicals, CPVC is a material that is gaining attention for being an alternative for metal piping in many end-use applications. CPVC offers numerous advantages that have improved the bottom line of industrial process water applications worldwide.
Corrosion resistance and lifetime
Corrosion is a common, ongoing problem in industrial environments. CPVC pipe and fittings demonstrate superior resistance to internal and external corrosion, eliminating process leaks, flow restrictions and premature pipe failure. Unlike metallic systems, CPVC industrial piping will not pit or scale, as it is inert to most mineral acids, bases, salts and aliphatic hydrocarbons. CPVC is formulated to stand up to many of the same aggressive chemicals that corrode steel, and it does so in temperature environments of up to 97°C.
In addition, external pipe coatings are not necessary because CPVC remains unaffected by even the most aggressive soil and air conditions. When installed outside and exposed to sunlight, specially formulated CPVC compounds with UV resistance exist. Should a portion of the piping need replacing, the plant’s own maintenance personnel can easily make the repair once they have received solvent-welding training. A CPVC piping system requires little or no maintenance when properly installed.
Due to CPVC piping having a Hazen Williams Factor of 150 – which remains the same throughout its lifetime – it has superior long-term hydraulic capabilities compared to metal piping, which experiences increased friction loss during the years of operation. As a consequence, the frequency of pipe replacements is reduced to a minimum (or even completely eliminated). The ‘smoothness’ of the pipe interior offers optimum flow rates allowing for smaller pumps and requiring less energy. The smooth inner surface resists scaling and fouling, thus minimising friction pressure losses in the fluid flow, granting an increased flow rate and possibly a smaller pipe diameter.
CPVC pipe systems have exceptional mechanical strength at the elevated temperatures at which industrial plants often operate. Most CPVC systems can be expected to maintain their pressure bearing capabilities for 50 years or more, providing long-lasting performance. These factors alone already lead to serious cost savings.
Ease of installation
CPVC is lightweight (roughly one-eighth the weight of comparably sized steel piping) and because it can easily be solvent-welded, less complex tools are required. Installation and maintenance are simplified; therefore the overall labour time is reduced. CPVC pipe and fittings are installed using a simple two-step solvent-welding process, which joins pipe and fitting by chemical fusion. Of course it is also possible to join CPVC products through hot-gas, extrusion or mirror welding when fabricators install, for example, a CPVC storage tank.
Additional safety
CPVC piping is safer to operate than metal systems as its thermal conductivity is lower. This not only reduces heat loss, but also keeps the overall surface temperature of the pipe lower, reducing the chance of burns to maintenance and operating personnel and minimises its contribution to the overall ambient temperature in the area of operation.
CPVC has a high flammability resistance as its limiting oxygen index is 60. It requires 60% of oxygen to be able to sustain a flame when burning. As our atmosphere only consists of 20 to 21% of oxygen, CPVC will not burn on its own and will not contribute to flashover. When tested according to EN 13501-1:2002 to determine its fire classification, CPVC achieves a rating of B-s1-d0 (low flammability, no smoke development, no burning drops).
CPVC industrial piping systems offer a range of benefits for industrial process water applications and can be safely used throughout nearly any industrial plant because of their corrosion resistance, long service life, temperature resistance, hydraulic capabilities and wide application range.
Although CPVC is resistant to a broad range of corrosive environments, it’s important to note that not all chemicals are compatible for use with CPVC. Lubrizol CPVC, the manufacturer of the compounds that Corzan Industrial Systems are made of, and its customers have tested hundreds of different chemicals to determine the system’s chemical resistance with Corzan pipes and fittings and have developed a chemical resistance programme to list the solutions that can be used with Corzan, providing installers confidence in the long-term performance of the system.
For more information, visit www.engineerlive.com/epe
Sinikka Freidhof & Jorge Solorio are with Lubrizol.