A Green Alternative to Pressure Pipe

At first glance, plastic materials look pretty much the same, and let’s face it: How many of us really learned enough back in chemistry class to look at the chemical names and fully understand a material’s chemical properties? Thus, we have a tendency to lump polymers in one group and to minimize or ignore the significance of which material you select.

In reality, there is a tremendous difference between plastics in terms of their composition. These differences begin at the basic molecular level and result in substantial differences in their toxicity, life safety, brittleness, chemical sensitivities, expected life, and recyclability.

The focus of this sidebar is on plastics used for large pipes for distributing potable water in institutional and commercial buildings, specifically chlorinated polyvinyl chloride (CPVC) and polypropylene-random (PP-R).

CPVC is produced by chlorination of polyvinyl chloride (PVC) resin. As the name suggests, CPVC is about two-thirds by weight chlorine. In contrast, the building blocks for polypropylene (PP) are chains of hydrogen and carbon, with some longer and some shorter, giving it the characteristics of both strength and flexibility. Following are the properties of PP-R:

• Resistance to stress and cracking (i.e., high tensile and compressive strength)
• Low thermal conductivity
• High operational temperatures
• Resistance to most alkalis and acids, organic solvents,
• degreasing agents, and electrolytic attack
• Recyclable and non-toxic
• Easy to produce and assemble