HDPE pipe is a type of flexible plastic pipe used for fluid and gas transfer and is often used to replace ageing concrete or steel mains pipelines. Made from the thermoplastic HDPE (high-density polyethylene), its high level of impermeability and strong molecular bond make it suitable for high pressure pipelines. HDPE pipe is used across the globe for applications such as water mains, gas mains, sewer mains, slurry transfer lines, rural irrigation, fire system supply lines, electrical and communications conduit, and stormwater and drainage pipes.
The standard specification of HDPE pipes can be classified by both of their nominal pressure (the maximum pressure that an HDPE pipe can withstand) – PN 2.5, PN 4 or PN 16, and by the material used – PE100, PE80, PE63 or PE32.
The two most commonly used HDPE pipes include PE80 and PE100.
- PE 80 – gas pipe for natural gas distribution network with pressure rate up to 4 bars or drinking water pipe with pressure rate up to 16 bar. It is also an ideal piping material for industrial and wastewater applications.
- PE 100 – high demands piping applications that provide long-term strength and creep resistance. It has a significant advantage over PE 80 at low temperatures since it is extremely crack resistant down to -30°C
Although HDPE pipe is often estimated to last 50 years, they are in fact more likely to have life expectancies of 100 years. PIPA (Plastics Industry Pipe Association) and the Plastic Pipe Institute (PPI) have written technical white papers on HDPE design life. The PIPA paper is called “Life Expectancy for Plastics Pipes” which mentions that because of the fifty-year stress regression data, people who falsely assume that plastic pipe systems’ life expectancy is only fifty years. In fact, these pipe systems can be reasonably expected to last up to or more than 100 years. In Australia, PE pipes and PE fittings were introduced during the mid-1900s, mainly for irrigation or water supply, but also for gas, fuel, and other industrial applications. The use of this 50-year time interval, leads to a misunderstanding that it represents a 50-year pipe life. For pipe systems that have been correctly manufactured and installed, the actual life cannot be predicted, but can be expected to be over 100 years until major rehabilitation is needed.