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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.


The list of applications that are suitable for  Hiline e-Flex is vast, but typically, it is used above and below-ground, on domestic, commercial and industrial sites for conveying:

  •  District Heating
  •  Chilled Water
  •  Potable Water (optional)
  •  Hot Water (optional)

Manufacture and Standards

Pre-insulated pipes and fittings for thermal utilities are manufactured within an ISO 9001 accredited environment in accordance with EN 15632 Parts 1 and 2.

Service Pipes 

Cross-linked polyethylene (PE-Xa) in accordance with DIN 16892/93 with an oxygen diffusion barrier (EVOH) in accordance with DIN 4726.Hiline Flex Uno 2449 400x267c

Efficient Insulation

A key component in the efficiency of the Hiline pipe systems is our choice of CFC-free polyurethane foam to provide excellent levels of insulation – in accordance with the demands of the EN 253 standard. Using cyclopentane as the blowing agent, we achieve very-low lambda levels – which result in much-reduced energy losses to the media being conveyed by the service pipe. The effects of using a more efficient insulation don’t appear to be much at face value, but factor in a 30-year life-cycle cost of operating the system and the savings – both financial and environmental – mount up significantly. When looking at the life-cycle-costs of a district heating pipe network, the initial capital investment is typically around ten percent – with the biggest cost being the on-going operation.

  •  High-efficiency CFC-free, rigid polyurethane foam insulation

RHI Compliance

Hiline Flex pipe systems are deemed 'Properly Insulated' by the Renewable Heat Incentive (RHI) and therefore meet their strict requirements.

Outer Casing Pipe

The outer casing pipe is manufactured from seamlessly extruded, corrugated polyethylene (PE-LLD).

HilineFlex OpenClipShell Straight 2484 300x200

Site Jointing Techniques

Service Pipes

The jointing of PEX pre-insulated pipes can be carried out using the proven PEX-LOK compression-sleeve jointing system - giving a maintenance free, tight fitting joint.


Casing pipes

The sealing of casing pipes in the field are carried out with a mechanical, shroud jointing system that enables the easy installation of foam insulation in the joint area. 

Quality Assured

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 – such as EN 253, along with any that are pertinent to special applications. 

Additional Services

Pipe Coil Trailer HirePipe coil interior CMYK 7042 400x266

Pipe coils can be delivered to site on a specially-designed pipe coil trailer. These trailers, supplied on a rental basis, enables safe uncoiling and swift installation of Hiline e-Flex pipes straight into pre-prepared trenches. 
Flexible polymer-based pipe systems delivered to site in coils, albeit easier to install than steel systems, can be challenging to safely handle and in using Hiline Flex pipe coil trailers, the process is made much more simple and can reduce the number of operatives required on site. Please contact us for prices and availability.

Pipe Termination Pre-Fitting Service IMG 6937 PrepOfPipeEnds 400x267

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.

World-Class Support

At CPV we pride ourselves by the way in which we support our customers – from the moment that they first contact us through to their long-term operation and maintenance of a pre-insulated pipe network. As manufacturer, it’s important to us to ensure that our systems deliver exceptional performance throughout their working life. Therefore, we have established an array of world-class support services that help our clients every step of the way.

Design and Stress Analysis

designing district heating systems 400x167There are many factors that will affect the long-term integrity of a pre-insulated pipe system. Correctly identifying and dealing with the potential for thermal expansion of the pipe system is a critical element of the design process and we employ state-of-the-art sisKMR specialist stress analysis software. This package allows us to configure the pipe routes to keep the thermal expansion within safe limits and conform to the requirements of the EN 13941 standard for Design and installation of pre-insulated bonded pipe systems for district heating. Please click this link to find out more about our advanced stress analysis service for district heating pipe networks.


Training installers, supervisors and maintenance operatives, our brand new training centre allows for not only the theory, but hands-on practical experience in the correct method for installing the Hiline pipe systems. In addition to this, we also offer training courses in the design, installation, commissioning and maintenance of electronic surveillance systems – including the use of our own buried pipe network, on which we can simulate moisture faults as part of the practical training.

Tool sales and hire

We offer both the sale and short-term hire of all the specialist tools required to install the Hiline pipe system.

Trace and Maintained Heating Systems Support

In temperature-critical, special applications that require round-the-clock maintenance of a specific media temperature, we can supply the Hiline pipe system with Trace or Maintained Heating systems.

On-site support services

Whether it’s on-site training, site supervision or specialist advice, support and maintenance – our engineers are at hand to provide customer support as and when required.

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)