Plumber's Diaries

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  • Date July 8th, 2011 13:45
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  • All plastics are created from petroleum and have recently come under fire from environmentalists around the world. Scan the internet and you'll find countless articles about waste, massive ocean dead zones, and chemical tyranny. For better or worse, plastic isn't going anywhere anytime soon. Until it does, there are very notable differences between the plastics that are currently in the market. Of course, every design requirement dictates an individual solution, though not all plastics are created equally. When sourcing plastic for water piping needs, use HDPE pipes whenever possible.

    HDPE - High Density Polyethylene:
    At its molecular level, pure HDPE is made from carbon and hydrogen atoms. When combined a strong and dense piping solution, ideal for water pipes, results. HDPE's density enables pipes to withstand heat and load, making them appropriate for hot or cold water piping and applications with high compressive forces (buried pipe). HDPE can also be recycled (nearly infinitely), is durable, and can be non-toxic. Like all plastics, HDPE pipes are also not created equal. Similar to most industries, additives, product quality, and poor detailing can seriously undermine or reverse their benefits. When sourcing HDPE pipes, consider:

    A common failure for most materials, connections can either be a huge asset or major liability for HDPE pipes. When done right, HDPE pipes are fused together. Just like steel welding, this process creates a homogenous connection that is as strong as the pieces it connects. No additional hardware or nasty silicones or other sealants are needed. This can reduce the materials used and installation time. Performance may also improve as pipe diameters do not change, avoiding blockages. The quality of connections depends both on the base material and the expertise of the installer. Quality base materials should have a wall thickness that is consistent, and thick enough for the required weld. Installers should be trained specifically to cut and weld HDPE pipes. Some HDPE manufacturers offer this type of training.

    HDPE can be recycled, almost infinitely. I write 'almost' because its recyclability depends on its purity. When HDPE is commingled with other plastics, its properties are often degraded. When recycled, the result is downgraded plastic products, slowly headed towards a landfill. This also makes it very difficult for manufacturers to source HDPE from waste streams (it's typically not cost effective to verify the purity of reclaimed HDPE products). Manufacturers who claim their HDPE is 100% recyclable aren't necessarily lying, though the real validity of their claims depends on how their products are managed after use. I have not found a manufacturer with a reclamation program in China, and few companies would even have cause to start one. Most piping is sold through complicated distributor networks making it very difficult for manufacturers to track where their products end up. The logistics of this process are also complicated and very cost prohibitive, even if the materials could be located. Only manufacturers who sell directly to clients have a legitimate opportunity to create such a closed-loop economy. There is a distinct market opportunity for material brokers to emerge - brokers who source reclaimed materials and identify the inherent quality and composition of the reclaimed loot. Industry standards could also play a major role in reducing waste - if standards were harmonized, waste HDPE could universally be used by manufacturers looking to source recycled content.

    Fuel Source and Toxicity:
    Pure HDPE is also worth its weight as an energy source, literally. HDPE is made from petroleum - the weight of pipes is equivalent to the same weight of petroleum. More interesting, when burned pure HDPE doesn't off-gas dioxins or phthalates, two nasty persistent and bioaccumulative toxins that have brought the PVC industry under fire (no pun intended). The absence of reclamation programs is not always a major issue for pure HDPE as waste pipe is frequently used as a fuel source. The downside here is similar to that of recycling. Additives may be used in HDPE to create various performance needs. These additives may create dioxins, phthalates, or other harmful substances when burned. When commingled, it's difficult to know what is being burned. How to avoid this? Confirm the chemical composition of the HDPE you source. You may even consider requiring manufacturers to burn samples as part of your specification process.

    The upshot, quality HDPE solutions and qualified installers do exist in China, Hong Kong, and Taiwan. Drop us a line if you need more information.

    Geberit's strength test demonstration. Photo courtesy of Billy Hustace.

    Geberit's installation training center. Photo courtesy of Billy Hustace.

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