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Pipes are required to last a very long time. The engineered polymers used are very stable materials. The long life properties that can be problematic for single use applications, such as packaging, make them the perfect choice for infrastructure.
Plastic pipes have transformed the way we live, delivering essential services and utilities to our homes and communities. A long service life is critical for infrastructure. Plastic pipes supply drinking water, convey sewage and stormwater, protect network cables for more than 100 years.
Types of plastic materials that are durable and rugged. Unlike, commodity plastics, engineered polymers are designed to have specific molecular structures – strength, toughness, chemical resistance, UV resistance and ease of processability making them suitable for long life applications.
Long term strength of plastic pipes is tested in accordance with international standards – ISO 9080 Plastic piping and ducting systems – determination of the long term hydrostatic strength of thermoplastic materials in pipe form by extrapolation.
The preface extract of Australian Standard AS/NZS 1260:2017 states “…. Plastics pipe systems are often designed on the basis of 50 years extrapolated test data. This is established international practice but is not intended to imply the service life of drainage pipes is limited to 50 years. For currently manufactured and installed systems, the actual life cannot be predicted, but logically be expected to be well in excess of 100 years before major rehabilitation is required”.
Source: Simplyss, The Lifespan of Essential Household Items
One of the most important features of plastic pipes is their design life. They are intended and designed to last a very long time. When pipes are installed in a building it is expected that the pipes will last as long as the building. When pipes are installed in infrastructure applications then they are commonly required to have a life expectancy in excess of 100 years.
In typical environmental conditions, plastic materials are well known to last for a very long time. They do not biodegrade or corrode and generally their properties remain stable in the long term. These properties are ideal for a product such as pipes – a long life expectancy is required.
Plastics provide excellent protection and preservation of many products but often are single use. The inappropriate disposal of single use plastics can result in pollution and environmental damage.
Most plastic pipes used for water supply, sewerage and drainage applications are installed in ground. When these pipes reach the end of their serviceable lives (and this is a very long way off), they will be used as host pipe for some form of trenchless rehabilitation with yet another plastic system.
Did you know plastic pipes represent a very small portion of waste going to landfill? This was confirmed by the NSW Government audit of Construction and Demolition Waste. In one landfill site of 450,000 tonnes of waste less than 3% was plastics. The reason why is due to their very long service life, typically more than 100 years.
Plastic pipes and fittings are being recycled now! The common plastics used for pipe production like PVC and PE are thermoplastics and readily reprocessed. Scrap generated during manufacturer is reground and fed back into the manufacturing process.
Completing the circular economy…
After a service life in excess of 100 years a plastic pipe can be reprocessed into another pipe for another 100 years service life. This can be repeated up to and over 6 times!
Our commitment to the Australian community is simple – we aim to recycle the maximum amount of usable plastic pipe – find out more about PIPA’s recycling program and partners
The vast majority of plastic pipes are made from a single material and therefore easier to recycle.
An economical and versatile thermoplastic polymer, derived from vinyl chloride monomer – a chlorinated hydrocarbon.
PVC is 57% chlorine by mass which is sourced from the abundant natural resource – common salt.
Recyclability of PVC
Due to the long life of rigid PVC products and low volume in waste streams, there is no current limitation for the amount of recycled PVC that can be utilised. PVC has a high recyclability and can be mechanically recycled back into a pipe product performing the same structural function as one made only from virgin material.
Edge Environment, 2017, Environmental Product Declaration, PVC Non- Pressure Pipes for Building Applications, IPLEX, p.17
A tough, rigid and crystalline thermoplastic polymer produced via chain-growth polymerisation from the monomer propylene. It is the second most widely produced commodity plastic after polyethylene.
There are three main grades of polypropylene resin allowing for changes in specific properties as determined by the composition of the polymer chain.
Recyclability of PP
Although the PP pipes are most likely to be left in the ground at end of life, PP has a high recyclability and can be mechanically or chemically recycled to replace virgin polypropylene in new products.
Edge Environment, 2017, Environmental Product Declaration, StormPRO® and SewerPRO® Polypropylene Pipes, Vinidex, p.14
Is the world’s most widely used thermoplastic polymer and is produced by the polymerisation of ethylene gas, a derivative of the petroleum industry. The polymer consists essentially of long-chain molecules of very high molecular weight, made up of many thousands of the -CH2- repeating unit.
There are many different types of polyethylene for example:
Modern day polyethylene pressure pipes for conveyance of water or gas are made from a type of HDPE called PE100.
Recyclability of PE
Although the PE pipes are most likely to be left in the ground at end of life, PE has a high recyclability and can be mechanically or chemically recycled to replace virgin polyethylene in new products.
Edge Environment, 2016, Environmental Product Declaration, Polyethylene Pipes, IPLEX, p.11
Why is flexible packaging difficult to recycle?
Flexible packaging is more challenging to recover as it often involves multiple polymer layers/and or aluminium, which are difficult to separate adding complication to the recycling process, unlike most pipes which are made from one single material.
This ensures each material can be processed in the appropriate way, avoiding contamination resulting in an individual material that can be reused to make products.
Find out more about the recycling process for plastic pipes.
Pipes are engineered to withstand various loads and stresses for their entire service life.
Pressure pipes are designed to withstand the internal pressure created by the fluid being conveyed within the pipe. The fluid being conveyed creates both longitudinal and hoop stresses in the wall of the pipe.
Read more about Combined Loading of Buried Thermoplastics Pressure Pipes.
Buried pipes are also subject to external loads caused by installation, soil and traffic. The stresses are relaxing slowly over the course of time as the imposed loads are fully transferred into the surrounding soil and stabilising pipe deflection. The additional stresses caused by external loading do not result in reduced failure times when the pipes are internally pressurised. It has been shown that the visco-elastic behaviour of materials such as PE and PVC is a beneficial feature providing a long life for thermoplastics pressure pipes.
Research has been done to identity the relationship between cover height, soil type and compaction and their effect on the deflection of buried PP pipes used for stormwater drainage purposes when exposed to early loading. The results showed acceptable deflections below 3% for all installation conditions and buckling was never encountered.
Courtney Dunn’s presentation at Ozpipe Conference Sydney 2019, The Behaviour of Polypropylene Pipes – The effect of early loading and installation conditions on their deformation. Australian National University – Bachelor of Engineering honours.
VIEW THE PRESENTATION Durability is a result of product design
For plastic pipes it is intended that they can be installed (generally behind a wall or underground) and not require any maintenance or repair for decades.
Plastic pipes are therefore designed for long life. They withstand the forces they are subjected to; they do not corrode and resist chemical attack, they resist abrasion and maintain a smooth bore for easy fluid flow, they are designed not to leach secondary materials into the fluid flow which is important for drinking water applications.
Plastic pipes and fittings are made in a range of designs to suit the requirements of specific applications
For each type of material (PVC-U, PVC-M, PVC-O, Polyethylene, Polypropylene) and application whether be for pressure pipes and fittings or non-pressure drainage and sewerage pipes and fittings there are AS/NZS standards that define the required performance criteria in terms of strength, toughness, long term pressure carrying capabilities and other properties for the material being used. The material and physical characteristics of plastic pipes makes them the appropriate material of choice across multiple applications.
Water is the life blood of all farming operations and its security is essential. Plastics pipes are suitable for the complete range of farming applications. Pressure pipes for pivot, drip and micro-irrigation, stock watering and potable water supply. Non-pressure pipes for flood irrigation and stock watering systems.
Low cost, wide range of sizes and pressure capabilities, flexibility, toughness, UV resistance, ease of handling and installation are all advantages important to primary producers.
PVC pipes and fittings for plumbing and waste drainage applications is the choice of plumbers worldwide. Low cost, light weight and very long service life expectancy are the overwhelming advantages.
Polyethylene pipes are used extensively in gas distribution applications worldwide. In Australia the use of polyethylene in natural gas distribution systems is growing rapidly.
Polyethylene is lightweight, flexible and available in long coils to minimise the frequency of joints. It is ideally suited for a wide range of service conditions requiring very little maintenance. It has excellent abrasion resistance, flexibility, toughness, is totally unaffected by corrosion, tolerates high rates of ground strain and temperature fluctuation.
Coal seam gas upstream collection systems rely entirely on the unique properties of polyethylene pipe. In the past decade, in excess of 22,000 kilometers of polyethylene pipe has been safely installed in Queensland gas fields alone. This is equivalent to the entire reticulation network of Australia’s largest city. Polyethylene’s flexibility, toughness, long-length coil and ability to be reliably welded will ensure it remains the material of choice in this demanding application.
The use of plastics pipes in mining for water, waste, chemical and slurry transport is extensive. PVC, polyethylene and polypropylene pipes may be installed above or below ground. Polyethylene pipe is available with a highly weatherable, reflective white outer skin to protect against solar heat absorption. The pipes are light weight, long length, flexible and easy to transport and install. They are corrosion free, abrasion resistant, maintain a smooth bore and when properly installed, require very little maintenance.
PVC is ideally suited for telecommunication and power conduits due to its high impact strength, smooth internal bore, inherent straightness and large range of diameters. Flexibility, corrosion and UV resistance characteristics of PVC conduits makes them ideal for a wide range of installation conditions.
High density polyethylene (HDPE) is ideal for pipe lining and cable encasing, which makes it perfect for buried cable installations. Polyethylene has become the default conduit used in directionally drilled electrical and communications conduit applications.
The use of plastics pipes in potable water supply applications has been growing rapidly in Australia over the past three decades. Both PVC and polyethylene pipe have major advantages over competitive materials and as polymer technology keeps improving, the choice of plastics pipes for water supply infrastructure projects keeps increasing.
In many applications, plastics pipes have an expected life in excess of 100 years, during which they provide excellent performance and trouble-free service life. They are totally free from corrosion and because of their relatively light weight, are easy to handle, transport and install.
Plastics pipes are flexible and fatigue resistant and can withstand repetitive pressure surges. They provide a smooth biological growth free bore through the life of the product eliminating flow restrictions common to other materials.
The use of plastics pipes for both sewers and storm drains is extensive in North America, Europe and Australia. In addition, there is rapid growth in the use of plastics in-situ liners for the renovation of corroded, cracked and leaking metallic, concrete and asbestos cement sewer pipe installations.
Availability of large diameter plastics pipes provided design engineers an opportunity to select products based on cost and performance basis. Very long service life expectancy and low maintenance requirements are major advantages for the selection and use of plastics pipes for sewage and storm drain applications.
Immunity from corrosion and resistance to attack by many industrial chemicals make plastics pipes the obvious choice for industrial and chemical plant installations. As with all materials used in the construction of chemical plants, care must be taken in selecting the appropriate plastic material that will withstand the operating conditions.
The wide range of polymers used in manufacture of plastics pipes, valves and fittings provide a good range of products from which to select the appropriate material.
Polyethylene piping systems are well suited to installation in difficult industrial situations. PE pipe’s toughness, ductility and ease of installation makes it ideal for industrial compressed air reticulation.
Plastic pipes and fittings have been in service for decades. Testing has found that the properties and performance do not change over the long term.
PVC pipes were introduced in Europe in the 1950’s and in Australia in 1960. Conduits were the original product manufactured followed by pressure pipes and then sewer and drainage pipes. Several studies have been conducted to determine if there is any change in the product properties over time.
In 1985, PVC-U water pipes exhumed after 4 to 16 years’ service in the UK and concluded that ageing was not a significant factor influencing the performance of the pipes. Stress regression tests showed that all pipes would be expected to exceed a 100 year life under normal operating conditions
Long term strength of plastic pipes is tested in accordance with international standards – ISO 9080 Plastic piping and ducting systems – determination of the long term hydrostatic strength of thermoplastic materials in pipe form by extrapolation.
Find out more – Long Term Performance of PVC Pressure Pipes in a Large Rural Water Supply Scheme
In 2014, Folkman reported on quality control tests on 8 PVC-U water pipes that had been in continuous service between 20 and 49 years. The standardized tests 5 included pipe dimensions, acetone immersion, burst pressure and hydrostatic integrity tests. Samples of the pipe having been successfully tested after 49 years’ service had already passed all the quality control tests after 22 years’ service. This has demonstrated the intact ability of this quality pressure PVC-U pipe to perform its intended purpose after a half century.
Read Folkman’s Report on Validation of the Long Life of PVC Pipes.
In 2014, a European study showed long term performance of sewer pipes, solid wall and structured wall, made from PE and PP-B, both virgin material and excavated pipes that had been in service for 38 years. The study demonstrated polyolefin sewer systems will have an in-service life of at least one hundred years.
Read the report 100 year service life of polypropylene and polyethylene gravity sewer pipes.
Lars-Eric Janson concluded in his 1996 report Plastic Pipes – How long can they last? “that everything is pointing towards at least 100 years practical service life for today’s buried sewer pipes”
Australian Plastic pipe manufactures have their products independently certified, ensuring they meet high performance standards
Australian pipe systems are made to comply with Australian or International Standards.
They set out specifications and design procedures to ensure products and services consistently perform safely, reliably and the way they are intended to.
The various asset owners, utilities and regulatory bodies require that only product that complies with the relevant standards is used. Water supply and drainage pipework installations are regulated and only product that conforms to the relevant Australian standard is allowed to be installed. Standards help to maintain a high standard of installation and performance for our infrastructure.
There are over
70
Australian Standards relating to plastic pipes and fittings.
These standards cover all aspects from manufacturing, product specifications, other materials used in plastic pipeline systems, testing through to quality management systems
Plastic pipes have performed well in full life cycle assessments, demonstrating high sustainability standards across the life of the product.
It is a methodology used to assess the environmental impacts of a product or service across its whole life (from the extraction of materials, to its manufacturing, transportation, installation, use, and eventual end of life).
LCA studies have shown that among different pipes used for Drain / Waste / Vent (DWV), all plastic pipes are considerably better than the metal pipe alternatives.
Howard, 2009, LCA of Australian Pipes, p.C-ii.
Best environmental practice PVC (BEP PVC) guidelines were developed by the Green Building Council of Australia, in conjunction with PIPA and the Vinyl Council of Australia, a number of years ago to set the standard for best environmental practice PVC and PVC pipes and fittings manufacture. These benchmarks were subsequently incorporated into the AS/NZS product standards to facilitate and openly encourage:
The use of BEP PVC pipes and fittings can assist buildings to qualify for credit points where pipe and fittings can be shown to comply with the GBCA “Best Practice Guidelines for PVC in the Built Environment”.
Visit the GBCA website
An EPD is a registered document that provides relevant, verified and comparable information about the life cycle environmental performance of businesses and/or products developed specifically for B2B communication and in line with agreed international standards.
The use of independently verified EPDs assists designers and building owners to qualify for credit points in the GBCA Green Star sustainability ratings system for buildings and fit out.
Based on LCA studies, plastic pipes have a significantly better environmental profile than cast iron and copper pipes against all categories and across their whole life cycle.
Branz, 2008, STUDY REPORT Adaptation of the USGBC TSAC Report for Relevance to Australian DWV Pipe Final, p6.
The lower the Ecopoints signifies better environmental impact. Plastic pipes are substantially lower than Copper and outperform cast iron and ABS.
Edge Environment, 2013, Life Cycle Assessment of Australian Pipes, Update of 2009 year’s Report
Polymeric pipes typically outperform metal pipe for the 100mm pipe evaluated (this result may not be true for large diameter pressure pipe applications).
Howard, 2009, LCA of Australian Pipes, p.C-ii.
Edge Environment, 2013, Life Cycle Assessment of Australian Pipes, Update of 2009 year’s Report
