What's the Alternative?

A snapshot of non-metallic piping alternatives, namely CPVC and PEX, reveals a number of benefits including cost-savings, flexibility and efficiency.

By Barbara Horwitz-Bennett, Contributing Editor -- Consulting-Specifying Engineer, 5/1/2004

CONSULTING-SPECIFYING ENGINEER: What advantages do non-metallic piping systems offer over traditional plumbing?

DeANGELIS: CPVC and PEX are growing in popularity as acceptance levels increase for these non-metallic piping systems. CPVC delivers long-term performance benefits, such as not being susceptible to corrosion, pitting or scaling. CPVC also stands up to low-pH water, coastal salt air and corrosive soil. In industrial applications, CPVC is actually preferred for a multitude of chemical systems.

RATTENBURY: I have seen some applications of PEX tubing used in domestic water distribution. PEX offers a great advantage for retrofits or renovations due to its flexibility. It can be run through walls and stud bays much like electrical cable. The reduction in the number of joints also decreases the chance of leakage in the future.

KUWATCH: CPVC fire sprinkler systems can be used in all National Fire Protection Assn. (NFPA)-defined light hazard applications, which include NFPA 13, NFPA 13R and NFPA 13D. And CPVC plumbing systems can be used in all commercial and residential applications. It is important to note that all CPVC is not equal. Some CPVC resins and compounds are specifically developed to optimize performance for their individual applications, and are designed to meet or exceed existing code and approval requirements. CPVC, with extra listings or approvals, can be very valuable to both the engineer and sprinkler contractor due to increased flexibility of product use.

Industrial piping systems made from CPVC plastic offer a combination of corrosion resistance, mechanical strength and fire resistance for durability in process applications. When combined with its ease of installation and cost efficiencies, CPVC is ideal for applications that utilize corrosive chemicals at elevated temperatures.

Many chemicals in the process industry aggressively corrode most metallic systems, resulting in process leaks, flow restrictions and ultimately, premature failure. CPVC is inert to most mineral acids, bases, salts and aliphatic hydrocarbons, and compares favorably to other non-metals in these chemical environments.

CSE: Are there additional advantages of alternative piping strategies? What about disadvantages?

DeANGELIS: Although in some areas they are still considered "alternative" piping systems, plastic piping products provide owners, engineers and contractors with options. Advantages include cost efficiency, corrosion resistance, erosion resistance and long life. Disadvantages arise if the application exceeds the performance limitations of plastic piping, or sometimes there can be problems as a result of improper installation.

KUWATCH: With CPVC fire sprinkler systems, there are many benefits with owner occupancy. For example, with a hotel retrofit, one room can be vacated when installing CPVC vs. a whole floor, as is necessary when using metallic systems. CPVC can be fabricated in the field and is corrosion resistant, both inside and outside the pipe and fitting. The product also offers savings on design and field installation.

CPVC plumbing systems offer a number of advantages that make it ideal for new construction and replacement applications. For example, pipe and fittings are available in copper tube sizes from ½-in. to 2-in. CPVC industrial pipe and fittings can also be utilized in systems requiring larger sizes, and are available in iron pipe sizes up to 16-in. in diameter.

One other advantage is durability. CPVC piping systems have been in field testing and actual installations for more than 40 years, including hospitals, hotels, major universities and numerous high-rise applications.

Of course, one of the most attractive benefits is cost. An installed CPVC piping system can cost much less and is faster and easier to install than traditional metal systems. No torches are required, and pipe and fitting joints are solvent-welded quickly and firmly. In the long term, the system offers additional savings because it is highly energy-efficient. With its superior insulating properties, this keeps hot water hotter and cold water colder than metallic systems. And since the system reduces condensation, it also significantly reduces the risk of costly drip damage to walls, structure and contents.

Building owners and property managers concerned with water quality also appreciate the fact that, unlike traditional metallic plumbing systems, a CPVC piping system maintains water quality, as there is no leaching of metal or contamination of the water supply. And, since CPVC doesn't pit or corrode, the system is expected to maintain full water-carrying capacity throughout its entire life.

Some CPVC plumbing piping systems are also four times quieter than a metal plumbing system, which is key for hotels, college dormitories, hospitals and multi-family dwellings where it's critical to minimize guest disruption. In addition, not only does the system minimize water flow noise, but it also resists water hammer.

CSE: Do you find that building owners are hesitant to depart from more traditional piping systems? How do you educate them about alternatives?

RATTENBURY: Building owners, I find, are receptive to new technologies if they offer a cost savings.

KUWATCH: There is a hesitance, but that's because there are many misconceptions about these piping systems that need to be cleared up. Once the building owners become aware of the system's advantages, the acceptance of CPVC is very high.

DeANGELIS: The competitiveness of the construction market has driven people to consider every option to save money and improve quality, which has accelerated the acceptance of plastic piping systems.

Today, the tremendous volatility of the steel and copper markets has driven the cost of those piping systems through the roof and dramatically limited availability. This has motivated even the most traditional owners and contractors to consider alternative piping systems such as plastic. At this time, the product costs are fairly stable and much more affordable than steel or copper.

In general, we find owners receptive to considering plastic piping systems. Our focus has been to educate pipe installers about the benefits of plastic, while also dispelling some of the myths, such as the belief that copper pipe outperforms CPVC. Toward this end, we frequently hold training seminars.

CSE: In potable water applications, how resistant is alternative piping to chemicals such as chlorine?

KUWATCH: The performance and longevity of CPVC piping systems are not compromised by the nature of the potable water conveyed. CPVC products will not corrode or degrade from conditions arising from the source of the potable water or the constituents introduced to purify the water. The most aggressive drinking water, even when containing elevated levels of chlorine, will not detract from the performance or service life of CPVC systems.

DeANGELIS: Plastic has been proven to handle chemicals associated with potable water as effectively as other types of piping, if not better. In industrial process piping, plastics are used especially for their chemical resistance.

RATTENBURY: PVC and CPVC materials are commonly used in municipal water distribution piping and hold up well to chlorine or chloramine. PEX tubing (see "Chlorine and PEX" p. 28) is recognized by the International Code Council and the International Assn. of Plumbing and Mechanical Officials, and is listed by the National Sanitation Foundation. This all indicates that these listed products are suitable for domestic water applications. In addition, the inherent corrosion-resistant property of PEX and PVC also withstands dissolved oxygen and is not susceptible to galvanic corrosion like copper.