Polyethylene (PE) for drinking water piping systems (VX-TN-4Q)
PIPA and POP018
The Australian Plastic Industry Pipe Association (PIPA) has reviewed internationally published research to develop guidelines for polyethylene drinking water pipes in contact with chlorine-based disinfectants.
On the 29th June 2018, PIPA published an industry guideline POP018 – Polyethylene Drinking Water Pipes in Contact with Chlorine and Chloramine Disinfectants which addressed the use of PE in pipe systems using chlorine-based disinfectants.
For chlorine and chloramine disinfected systems at temperatures up to of 21°C and maintained within the aesthetic limits of the ADWG, the expected life of SDR11 PE100 and PE80 is not adversely affected.
POP018 also identified that in areas where higher water temperatures are coupled with an aggressive oxidative environment, the combination of any of the following factors may compromise the PE pipe systems:
- Continuous elevated water temperatures
- High levels of disinfectant chemicals (including Chlorine & Chloramine)
- Water acidity (pH level)
- Operating pressure & velocity
- Installation conditions
- Pipe diameter and pressure rating
- Pipe material
Measures to Improve PE Pipe Service Life
If POP018 guidance does not recommend the use of existing PE material the following measures may improve service life:
- Adjusting water chemistry to a more favourable ORP value
- Taking steps to reduce the temperature of the pipe (e.g. increased installation depth)
- Increasing the size (DN) of the PE pipe
- Reducing pipe wall stress by lowering system pressure or increasing the thickness of the pipe wall (i.e. lower SDR)
- Selecting pipe manufactured from PE resin with an enhanced resistance to chlorine disinfectants
- PE with enhanced resistance to chlorine
- POP018 discusses the Chlorine Classification (CC) index set out in ASTM D3350:2014 “Standard Specification for Polyethylene Plastics Pipe and Fittings Materials”.
US standards and Plastic Pipes Institute (PPI) technical notes specify PE materials and their resistance to oxidation as follows:
|PE Material Class for
|Oxidative Resistance (ability to withstand elevated chlorine, temperature, pressure over time)|
Higher classification materials will withstand higher levels of chlorine, temperature and pressure over time.
Note: POP018 assumes existing PE100 materials align with the “base” material in the PPI technical notes.