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Hiline e-Flex - Pre-insulated PEX Pipe System

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A high-performance pre-insulated flexible pipe system for district heating and cooling applications.

Suitable for temperatures up to 95°C and a maximum working pressure of 6 bar, the pipes are available in sizes ranging from  25mm up to 160mm (OD), supplied on rolls of up to 800 metres in length (20mm OD). Available with single and double service pipe configurations within a single outer casing pipe.

Available Dimensions

Available Dimensions

  • Available in with single or twin service pipes in one outer casing
  • UNO (single) pipes from 25 mm up to 140 mm diameter
  • DUO (twin) pipes from 25+25 mm up to 75+75 mm diameter
  • Delivered in coils of up to 800 metres (25 mm OD)


  • District heating up to 95°C (max)
  • Chilled water
  • Hot water (optional)
  • Potable water (optional)
Manufacture and Standards

Manufacture and Standards

  • Manufactured within an ISO 9001 accredited environment
  • In accordance with EN 15632 Parts 1 and 2
  • Deemed to be 'properly insulated' for RHI projects
Service Pipe

Service Pipe

  • Cross-linked polyethylene (PE-Xa) in accordance with DIN 16892/93
  • Integral oxygen diffusion barrier (EVOH) in accordance with DIN 4726
Efficient insulation

Efficient insulation

  • High-efficiency CFC-free, rigid polyurethane foam insulation
  • Different thicknesses available (Series 1 and 2)
  • Bonded construction with exceptional thermal performance
  • Low lamda levels results in improved operational costs and reduced environmental impact
Tough outer casing

Tough outer casing

  • Seamlessly-extruded corrugated LDPE casing
  • Buried directly in the ground
Secure Service Pipe Joints

Secure Service Pipe Joints

The PEX-LOK axial compression service pipe jointing system is a fit-and-forget solution that offers the very highest levels of joint tightness and reliability

  • Quick and easy to fit with industry standard tools
  • Tools available for sale or hire
  • Installation training available
Robust Casing Joints

Robust Casing Joints

  • Range of secure joints and fittings available
  • Easy-to-fit clip-together casing joints (pictured)
  • Heat-shrink sleeve casing joints also available
  • Joint insulated with two-part PUR foam kits
RHI Compliance

RHI Compliance

Perfect for biomass-fuelled heating projects, Hiline Flex pipe systems are deemed 'Properly Insulated' by Ofgem for the Renewable Heat Incentive (RHI)
Pipe Coil Trailer Hire

Pipe Coil Trailer Hire

Pipe coils can be delivered to site on specially-designed pipe coil trailers.

  • Trailers supplied on a rental basis
  • Enables pipe to be uncoiled straight into the trench
  • Safe handling with fewer on-site operatives
  • Speeds up installation and lowers costs
Please contact us for prices and availability.
Pipe Termination Pre-fitting Service

Pipe Termination Pre-fitting Service

For clients looking to perhaps link just two buildings, we now offer the choice of a factory-fitted heat shrink end cap and pre-fitted PEX-LOK axial compression termination connector with either a BSP thread or steel weld adaptor. Cutting down installation time and reducing the need to hire specialist tools, the pre-fitting service is available on coils of Hiline e-Flex with PEX service pipes diameters up to 63mm OD (DN 51.4mm).

Please ask our sales team for details of this service when making an enquiry or placing an order.

Sector-Specific Solutions

Off-Site Fabrication Services

Hiline Project References

  • Academy Central Residential Developments
  • Arup Campus, Solihull, Birmingham
  • Ashley Park Housing Association
  • Astley Ainslie Hospital
  • British Antartic Survey
  • Calendar Park, Scotland
  • Camelford Primary School
  • CEU University, Leeds
  • Edgbaston Priory Club
  • Falkland Islands
  • Government Facilities
  • Lancaster University, New Sports Centre
  • Leicester Citywide DH Network
  • Northwood Barracks, London
  • Rolls Royce, Derby
  • Shenley Wood Retirement Village
  • Swansea University
  • The British Embassy, Harare, Zimbabwe
  • Warwick University
  • York University Accommodation Block

The True Cost of Insulation

The effects of using a more efficient insulation don’t appear to be much at face value, but factor in a minimum 30-year life-cycle cost of operating the system and the savings – both financial and environmental – mount up significantly. The Hiline range of pre-insulated pipe systems are available with increased levels of insulation thickness – which for a relatively small additional investment at the time of installation – will yield significant savings during the lifetime of the system.

To illustrate this point, take an example scenario in which a 5,000-metre long network (flow and return) consisting of DN150mm steel pre-insulated pipes circulating hot water at a flow temperature of 100°C. If fuelled by a natural-gas-fired boiler, constantly operating all-year-round, the system with standard insulation – over its nominal 30-year life – will lose heat to the equivalent of around £3.65 million’s-worth of gas(*) and emit 15,250 tonnes of CO2.

By making a small additional investment – equivalent to around 10 percent of the material cost at the time of installation – in order to upgrade the Hiline pipe system’s insulation thickness to Series Two, the cost of the heat lost would be reduced by some £1.2million – also saving 5,091 tonnes of CO2 from being emitted. The graph shown demonstrate the effects that this can have.

Figure 1

(*)Basis of Calculations used for example costs:

- Gas supply tariff 3p/ kWh
- Gas costs increase by 2.5% per annum for the 30-year calculation
- Gas boiler efficiency 80%
- Carbon factor for natural gas = 0.1836 kgCO2/kWh (source: Ofgem)