by Mark Heathcote, Plastics Industry Pipe Association of Australia Executive Manager
When it comes to plastic pipe most people immediately think of the plastic pipe systems around their home – PVC drain waste and vent systems, stormwater pipe and electrical conduits. An increasing number of Australians would also recognise pipes made from PEX, multilayer composites and polybutylene, used for gas and hot and cold water pipes inside their homes. What many may fail to appreciate is that every major utility supplying critical services to homes and businesses relies heavily on the long-term performance of plastic pipe systems.
Australia’s gas distribution network has depended more on plastic pipe systems than any other material for many years. The story is similar for water and wastewater utilities – they now primarily use plastic pipe systems to deliver clean drinking water and safely remove wastewater. The electrical cables buried in your street are protected by a polyethylene or PVC conduit, as are the communications utilities. And it’s not just the urban utilities that take advantage of plastics. In rural and regional Australia plastics are also the material of choice for irrigation projects, and stock and domestic networks such as the 8,500km Wimmera Mallee Pipeline System.
There are a variety of plastic materials to choose from and each possesses different material properties which can be used to determine which best suits any given application. The materials commonly found in pipe and conduit systems for utilities are polyvinyl chloride (PVC), polyethylene (PE) and polypropylene (PP). Before discussing where each of these materials is used, one common aspect must be addressed – sustainability.
The more we study the life cycle of materials the clearer it becomes that plastics are genuinely the most sustainable material for pipelines in comparison with alternatives such as cast iron, steel, copper and concrete. Life cycle analysis (LCA) examines every aspect of the material, from the raw components to the finished product, and can include installation, operation and end-of-life aspects such as recyclability.
LCA’s form the basis for comparing materials and are used extensively in a variety of sustainability rating tools. The Infrastructure Sustainability Council of Australia’s rating tool and Green Building Council of Australia’s Green Star tool both use LCA’s as key elements in their rating systems. LCA comparisons between plastics and alternative pipe materials show that plastic pipe systems consistently outperform other materials. Peer-reviewed studies completed in Australia and Europe which assessed the life cycle of drainage and pressure pipes also found that plastics were by far the best performers (see references).
While many would expect PE and PP to outperform the alternative pipe materials in terms of sustainability, some may be surprised to learn that PVC does exactly the same. Many misconceptions about PVC pipe remain, some of which we will dispel here. PVC pipe contains no plasticisers (including phthalates). In Australia PVC pipe contains no heavy metal stabilisers (i.e. lead), as mandated in Australian product standards for PVC pipe — the only national product standards for PVC pipe to do so.
The Australian plastic pipe industry is committed to responsible sourcing, manufacture and recycling of PVC. Our industry has embedded the Best Environmental Practice (BEP) requirements developed by the Green Building Council in the Australian product standards to make compliance, procurement and identification simpler and more effective. All the raw material requirements and waste management improvements involved in the BEP requirements are certified by independent third party certification bodies.
Australia is one of the major developers and users of oriented PVC pressure pipe (PVCO), which uses less than half the raw material to achieve the same pressure capability in comparison with PVCU pressure pipe, which still forms the basis of pressure pipe in the US. PVCO also has significantly improved fatigue and impact resistance over the standard PVCU material, resulting in better overall performance. In terms of non-pressure pipe in Australia, the industry utilises material efficient multilayer and structured wall pipe and conduits to achieve a 20-30 per cent reduction in material usage while maintaining the same operational performance and life expectancy as traditional PVC pipes. In short, we do much more with less.
When it comes to recycling, all the common plastic pipe systems PVC, PE and PP are readily recycled and are being recycled now. Almost all post-industrial waste is recycled and we are also recycling post-consumer pipe waste. For example, over 650 tonnes of post-consumer PVC pipe, mostly sourced from demolition sites or construction waste, was recycled by the industry last year. Due to the nature of the material and the innovative product range the recyclate is used to manufacture new pipe with the same life and performance expectations as pipe made from virgin material. Not only does plastic pipe connect Australia, it is also very much part of the recycling process.
PIPA has worked with key environment groups such as the Green Building Council of Australia (GBCA). Romilly Madew, Chief Executive of the GBCA, recently used work done with PIPA as an example of a collaborative success story in the green building sector. In an article she wrote for the GBCA Newsletter in August Ms Madew said, “The trust and transparency developed during the process of collaborating with PIPA gave us the confidence to make some significant changes, as well as the opportunity to examine our industry in a way not thought possible.” These comments were in the context of the development of Best Environmental Practice PVC, and highlight how effective our collaboration has been, and continues to be, with the GBCA.
There is so much emphasis on sustainability today because it underpins the plastic pipe industry’s relationships and credibility with our stakeholders, the most important of which is the broader community. While our achievements are considerable and measurable, we are committed to making further improvements wherever and whenever possible.
It makes sense to start with the most commonly used engineering plastic for pipe applications – PVC. PVC has been used for infrastructure pipes in Australia for around 50 years in both pressure and non-pressure applications. PVC is the best performing pressure water pipe system in the country – based on CSIRO analysis of performance data from the Australian water agencies. PVC is also the most commonly used material for sewer and drainage pipe systems. In all these applications PVC pipes’ resistance to the corrosive effects of the soil they are buried in, and the effects of the water and wastewater they transport are key elements to their success. Combine this with structural integrity and a simple, effective jointing system and you can appreciate why these systems perform so well.
PVC also finds major applications in buried electrical and communications networks where its insulating properties, simple installation and rugged performance make it an attractive option for the conduits protecting electrical supply networks and communications cabling.
PE is another engineering plastic commonly used for pipe in utility applications. Most of the PE pipe in Australia is used for pressure applications in water, wastewater, gas distribution and gas gathering. PE is also commonly used for electrical and communication conduits. Whilst PE is often installed in traditional open trench conditions, the welded joint system and the ability to produce it in long coils means PE systems are well suited to trenchless installation methods like directional drilling and sliplining. These long continuous lengths also enable the use of innovative installation methods such as plough-in. Trenchless techniques are increasingly favoured by utilities, not only because of their cost advantages but because their small construction footprint generally minimises disruption to traffic and pedestrian access, in addition to reducing impact on the environment.
Finally there is PP, which is used primarily for non-pressure applications like sewer and stormwater drainage by Australian utilities. The attraction of PP systems stems from their light weight, simple and effective jointing and excellent corrosion resistance.
Put simply, plastic pipe and conduit are an integral part of Australia’s utility infrastructure.
1. Adaptation of the USGBC TSAC Report for Relevance to Australian DWV Pipe, Nigel Howard, Branz 2008.
2. A suite of Environmental Product Declarations commissioned by TEPPFA and undertaken by independent group the Flemish Institute for Technological Research (VITO) to measure the environmental footprint of various plastic pipe systems based on life-cycle assessment. The work was validated by the Denkstatt sustainability consultancy in Austria. Those most relevant to infrastructure pipe options in Australia are:
• Polyethylene pipe systems for water distribution (PE);
• Bi-oriented Polyvinylchloride MRS 45 MPa pipe system for water distribution (PVC-O MRS 45 MPa).
• PVC solid-wall sewer pipe systems for drainage and sewage (PVC solid wall);
• Polyvinylchloride multilayer sewer pipe system with a foamed core (PVC Multilayer Foam);
• Polyvinylchloride (PVC-U) multilayer sewer pipe system with a core of foam and recyclates (PVC Multilayer Foam + Recyclates);
• Polypropylene structured (twin) wall sewer pipe system (PP sewer twin wall).
The Plastics Industry Pipe Association of Australia – PIPA – is the peak industry body representing the interests of Australia’s plastics pipes, fittings and raw material suppliers. It promotes the correct use and installation of safe and environmentally responsible plastics pipe systems. Details about any of these systems and links to the companies that supply them can be found on the PIPA website: www.pipa.com.au/