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Hiline FibreFlex Pro - Pre-insulated Reinforced Polymer Pipe System

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A higher-performance reinforced pre-insulated flexible pipe system for higher-temperature district heating applications

Hiline FibreFlex and FibreFlex Pro are cutting-edge pre-insulated, flexible pipe systems that combine a high-modulus aramid mesh reinforcement with modern polymer materials in a multi-layer pipe construction. This significantly improved structure allows plastic pipes to be used at high operating pressures of up to 16 bar and operating temperatures of up to 115°C peak.

A Replacement for Steel

This makes Hiline FibreFlex and FibreFlex Pro ideal alternative, or complimentary, piping solutions to rigid pre-insulated steel pipes commonly found in district heating heat networks. Additionally, they can provide an alternative to conventional pre-insulated PEX pipes offering higher performance and higher factors of safety.

Composite Construction

(click on icons to reveal the labels)

PE-Xa service pipe

Adhesive layer

Aramid fibre mesh

Service pipe jacket with oxygen barrier

PUR foam insulation

LDPE outer casing

  • PE-Xa service pipe

  • Adhesive layer

  • Aramid fibre mesh

  • Service pipe jacket with oxygen barrier

  • PUR foam insulation

  • LDPE outer casing


    Hiline FibreFlex Pro is a highly-efficient reinforced pre-insulated pipe system that’s perfect for district heating applications at higher pressures and temperatures than FibreFlex or standard PE-Xa pipe.

    • Maximum continuous operating temperature (30 years): 95°C
    • Maximum temperature (peak): 115°C
    • Maximum operating pressure (30 years): 10/16 bar at 95°C
    • Thermal conductivity: ≤ 0.0210 W/mK
    • Service pipe: cross-linked polyethylene (PE-Xa) reinforced with aramid fibre mesh
    • Insulation: PUR (CFC-free) - available in Series 1 and 2 thicknesses
    • Outer casing: seamlessly extruded corrugated LDPE

    Available in sizes ranging from  32mm up to 160mm (OD), Hiline FibreFlex is supplied on rolls of up to 550 metres in length (25mm OD). Single and double service pipe configurations available within a single outer casing pipe.

    Complete System

    Complete System

    The Hiline FibreFlex system has a comprehensive range of fittings and accessories to ensure that it can be adapted to suit all possible configurations – including transitions to pre-insulated pipe systems with different types of service pipe – such as steel.
    Greater Thermal Efficiency

    Greater Thermal Efficiency

    Both FibreFlex and FibreFlex Pro pipes are insulated in one continuous manufacturing process using a CFC-free bonded polyurethane foam with an outstanding thermal conductivity value of l≤0.021 W/mK at 50°C.

    As the insulation layer has a lower thermal conductivity than conventional pre- insulated steel pipes (l=0.07 W/mK), in diameters up to 80 mm, the FibreFlex Pro system's heat loss is lower than insulation series S3 pipes and in larger diameters, heat loss is lower than series S2 pipes (see graph).

    When compared to conventional, bonded preinsulated PE-Xa pipes, the heat loss can be up to 17% lower for the FibreFlex system and even better when compared to non-bonded pipes.


    Available in service pipe diameters from DN20 to DN129mm, FibreFlex and FibreFlex Pro are ideal solutions for:
    • Biomass district heating networks
    • High-temperature city heat networks
    • High-pressure heating networks supplying high buildings
    • High-pressure heating networks in hilly areas
    • Special applications at operating temperatures up to 115°C and pressures up to 10 bar
    On-Site Flexibility

    On-Site Flexibility

    The reduced pipe wall thickness makes both systems more flexible to install, significantly increasing their range of application in district heating systems. In addition this includes a full range of fittings and accessories to meet the design requirements of all district heating pipeline projects.
    Strong and secure fittings

    Strong and secure fittings

    FibreFlex and FibreFlex Pro systems are quick and easy to join using specially designed compression fittings, incorporating a unique polymer sleeve, which is inserted between the fitting’s outer sleeve and the service pipe.

    A steel insert is then easily fitted inside the pipe, without the need for the pipe end to be expanded. This provides a robust connection with maximum joint integrity.
    Quality and Standards

    Quality and Standards

    The FibreFlex pipe system is certified OFI CERT ZG 200-2 Class A Technical Specification (in line with EN 15632-2). Hiline systems are manufactured in modern, EN ISO 9001-approved production facilities, using quality-assured materials that comply with all relevant design standards and tolerances for district heating and cooling, along with any that are pertinent to special applications.
    Saving Time and Money

    Saving Time and Money

    Delivered to site coiled in continuous lengths of up to 550 metres, on-site joints can be kept to a minimum making installation a quick and secure process.

    Project Example
    In a project where a heat network of 1,400m of FibreFlex piping was installed, it could be demonstrated that when compared to installing the same network in pre-insulated steel, there was an installed cost saving and a significant reduction in the network installation time (see graph).

    Hiline FibreFlex and FibreFlex UNO

    TypeService PipeNominalOuter CasingMinimumMax Length
      d x s DN D Bending Radius  
      mm  mm


    m m
    32/ 91 32.0 x 2.5 27.0 91 0.90 550
    40/ 111 40.0 x 2.8 34.4 111 0.90 410
    50/111 47.6 x 3.6 40.4 111 0.90 410
    63/126 58.5 x 4.0 50.5 126 1.00 300
    75/142 69.5 x 4.6 60.3 142 1.10 225
    90/162 84.0 x 6.0 72.0 162 1.20 149
    110/182 101.0 x 6.5 88.0 182 1.30 86
    125/202 116.0 x 6.8 102.4 202 1.40 80
    140/202 127.0 x 7.1 112.8 202 1.40 80
    160/225 144.0 x 7.5 129.0 225 1.60 36

    Hiline FibreFlex and FibreFlex Pro - DUO

    TypeService PipesNominalOuter CasingMinimumMax Length
      d x s DN D Bending Radius  
      mm mm 


    m m
    32 + 32/126
    2 x 32.0 x 2.5 27.0 + 27.0 126 1.00 300
    40 + 40/142 2 x 40.0 x 2.8 34.4 + 34.4 142 1.10 225
    50 + 50/162 2 x 47.6 x 3.6 40.4 + 40.4 162 1.20 149
    63 + 63/182 2 x 58.5 x 4.0 50.5 + 50.5 182 1.30 86
    75 + 75/202 2 x 69.5 x 4.6 60.3 + 60.3 202 1.40 80