Pipes, valves & fittings
Plastic myths unravelled
Durapipe’s building services brand manager, Des Dolan, answers some of the misconceptions regarding the performance of plastic pipework systems
W
hile plastic pipework systems are now readily accepted as a viable alternative to traditional metal materials, there are still
many in the building services industry that are mistaken about the performance capabilities of plastic pipework products. Outlined below are some of the misconceptions
uncovered in the latest Durapipe industry insight research
Myth: Plastics are more expensive Fact: The mistake is often made of comparing initial material costs, but when looking at the installed costs of a system, plastics offer significant cost savings. The lightweight nature of plastic pipe systems, combined with their quick and simple jointing methods, significantly reduces the installation labour time and costs, offering installed cost savings of up to 50% compared with steel or copper systems.
Myth: Plastic pipes snake due to thermal movement Fact: While it is widely acknowledged plastic materials expand and contract more in comparison to metals, thermal expansion in plastic pipes can be easily catered for if addressed at the design stage. The simplest and most cost effective method of
catering for thermal movement is to utilise the natural flexibility of the pipework system by building in changes of direction to the network design. The direction of pipe movement can be controlled by the use of anchor points at strategic positions. Other cost effective solutions include installing expansion loops, bellows, flexible hoses and expansion compensators.
Myth: Plastics are high maintenance Fact: Plastic pipe systems require less maintenance than traditional materials, such as copper and steel. Corrosion is the biggest cause of maintenance and replacement costs in metal systems, with unseen corrosion in copper and steel HVAC systems having the potential to cause severe damage and having a significant impact on operational efficiency. As a result, metal pipework systems need to be continually monitored, with regular flushing of the system scheduled, alongside taking frequent water
24 August 2017
samples to ensure the water quality is not adversely affected by any corrosion. With plastic pipework systems being completely corrosion resistant, this is not an issue and eradicates associated maintenance and repair time and costs. In addition, the smooth bore of plastic pipe systems
ensures no limescale can build up within the system, resulting in less friction loss and guaranteeing that a consistent flow rate is maintained throughout the life of the system. With optimum flow levels maintained, minimal maintenance and repair work is required to ensure the system operates efficiently.
Myth: Plastic pipe systems aren’t designed to last Fact: Plastic pipe systems have a 50-year design life, with the operational performance remaining at the same level throughout the lifetime of the system. The smooth bore of plastic pipe resists limescale build- up, ensuring flow is not restricted and continues at the same rate throughout its working life.
Myth: Plastics are more likely to encourage the growth of bacteria, such as Legionella Fact: The smoothness of the pipe material is an important factor; while the surface of some metallic pipes is rough, the smooth bore of plastic pipes helps to limit biofilm development.
Myth: Plastics have low impact resistance Fact: While not all plastic systems boast impact resistance, ABS is in fact an extremely tough material that provides very high impact resistance and the pipe system remains ductile even at temperatures as low as -40°C. Polypropylene is also a very robust material, remaining ductile down to -20°C.
Myth: Plastics are flammable and a fire hazard Fact: The plastics pipes industry has never claimed that plastic pipes are non-combustible. In a real situation, however, the use of exposed pipework within a room is unlikely and there has been no report, over the last 50 years, that the use of plastic pipes has contributed to any fire-related damage or injury, or increased risk to a property in the event of a fire. In the UK, there are strict building regulations on
the use of plastic and all above ground drainage materials, which state that pipes should be installed within a duct or boxed in behind plasterboard. As a result, plastic pipework should always be concealed behind material of specified fire resistance, with furnishings and fittings much more likely to contribute to the spread of fire than any plastic pipes.
Myth: Plastic gives off toxic gases when it burns Fact: Some plastic materials can give off trace amounts, but not enough to be classed as hazardous in the event of a fire. As with many flammable materials, the primary hazard is smoke. All plastic products give off gases when the material is burning. The predominant gas with PVC-C, for example, is carbon dioxide, which is generally considered harmless.
Myth: Plastics are not sustainable Fact: Plastic pipework systems offer strong sustainability credentials throughout all stages of their lifespan, requiring significantly less energy to manufacture, transport and install, compared with metal alternatives. At every stage of its lifecycle, a plastic pipework
system reduces the level of energy consumption, compared with metal pipe systems. On a typical commercial building project, the real impact of using plastic pipe and fittings equates to a 2,314kg CO2 saving, compared with copper, and a 3,606kg CO2 saving compared with carbon steel. While one plastic pipework system may not be suitable for a specific application, it does not mean all plastics should be overlooked. Unlike metal systems’ ‘one product fits all’ approach, each plastic pipework system has individual performance capabilities that have been purpose-designed for a specific application and so will offer enhanced installation and operational benefits, when compared with traditional systems. It is important for manufacturers and suppliers of plastic products to come together and educate the building services industry on their performance capabilities and the benefits they can offer specifiers, contractors, installers and end users.
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