Are any special pipes available for specific applications?

Yes. The PE pipe producing industry is very innovative in developing pipes for special applications and to be more cost-effective in dealing with installation and service needs.

The special pipes are mainly multi-layer materials. These are co-extrusions of different thermoplastic materials to form pipes with two or more layers in their walls, with each layer performing a specific function.

The multi-layer pipes may have:

• A harder thin outer layer to protect the main body of the pipe from damage where good quality bedding is not available, where installation is with directional drilling through coarse, granular soils, or where installation is by pipe bursting.
• A stiffer inner layer to improve crack resistance in specific conditions.
• A thin, peelable outer layer to obviate the need for scraping prior to electrofusion, thus making the fusion process simpler in difficult conditions.
• A metallic foil sandwiched between two layers of thermoplastic to protect potable water against any permeation of contaminants in the soil or ground water and to assist in detection of the buried pipe from the surface.
• Certain combinations of the above.

References

ISO 9623:1997 PE/metal and PP/metal adapter fittings for pipes for fluids under pressure - Design lengths and size of threads - Metric series
ISO 9624:2019 Thermoplastics pipes for fluids under pressure - Mating dimensions of flange adapters and loose backing flanges
ISO/TS 10839:2022 Polyethylene pipes and fittings for the supply of gaseous fuels - Code of practice for design, handling and installation