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Flexalen PU

High performance, flexible pre-insulated system
Pre-insulated pipe PU

Flexalen® PU is a pre-insulated plastic pipe system consisting of fully flexible and semi-flexible pipes (SL). The flexible pre-insulated pipe system is produced conform to the European standard EN15632-1, 2 and KIWA system certified as well as third-party controlled according BRL KOMO 5609-2. The PB service pipes are conform to EN-ISO 15876. The PUR foam and HDPE casing pipe of the semi-flexible pre-insulated pipes (SL) fulfil the functional requirements according EN253.

District heating systems with Flexalen PU

Flexalen PU was specifically developed for mid to large scale heating networks that require the best possible flexibility and the highest insulation class for plastic pipe systems. The system comes in single and double; in coiled pipe from DN20 to DN80 and straight lengths from DN50 to DN300. The Flexalen PU pre-insulated pipe consists of:

  • Polybutene (PB-H) Service pipe: a flexible polyolefin material that assures quick and reliable assembly, 50-year lifetime, while being the best in class for pressure and temperature rating.

  • Bonded Polyurethane (PUR) insulation with excellent insulation values (λ ≤ 0.023 W/m∙K for coiled and λ ≤ 0.030 W/m∙K for straight pipe.

  • Corrugated Low-Density Polyethylene (LDPE) casing for the coiled pipes to protect the pipe against risk of outside damage and allow for maximum flexibility.

  • Smooth High-Density Polyethylene (HDPE) casing for the straight pipes to protect the pipe against any risk of outside damage.

Proven efficiency

Quicker to install and lower operation costs are the key reasons client chose for Flexalen PU. Contact your local Flexalen representative for case studies or further info.

Why choose Flexalen PU pre-insulated pipes?

  • Permanent corrosion-free
  • Highest insulation class for plastic pipe systems.
  • Large network capacity with service pipes up to OD315mm
  • Full compatibility with Flexalen 600: combine highest insulation class of main lines with the most flexible house connection lines
  • Safest choice with homogeneous welding and high-pressure rating 95°C/8bar, for increased reliability
  • Thermaflex service: Support with integrated network design, calculation tools, training and on-site support

Technical support

Our technical support team and network engineers are ready to support you with:

  • Network design optimization
  • Network balancing and dimensioning
  • Putting together Bill of Material
  • Double check design and BOM during order
  • In house training facilities and programs
  • Technical assistance on site
  • Instant remote assistance


The Flexalen PU pre-insulated pipes are available as a single (DN20 to DN300) and double pipe system (DN20 to DN65). Flexalen PU coiled pipe is available up to DN80. Flexalen PU SL straight pipes are delivered in lengths 11.8m (DN50 to DN200 mm) or 3/5.8/6m (DN200 and DN300).

  • Specificities

    Flexible coiled pipes and Semi-flexible sticks

    Safe welding technology and proofen compression fitting system.

    Full range of accessories

    Safe and secure operation

    Long lifetime expectancy 

  • Pressure rating




  • Service temperature

    Wide temperature range

    Minimum -10°C

    Maximum 95°C 

  • Additional information

    For more details contact Thermaflex or download the technical datasheet!

  • Availabilities

    Service pipes: OD25 – 315mm

    Flexible coiled:

    • Single – OD25-90
    • Twin – OD25-75

    Sticks single: OD 63-315mm


Radius 10 Km
200 Km
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