hiline gre 1400x500

Hiline GRE - Pre-insulated GRE Pipe System

A pre-insulated rigid GRE pipe system for district heating, cooling applications 


Hiline GRE 50pxH

Hiline GRE is a rigid, pre-insulated glass reinforced epoxy (GRE) pipe system specifically developed for the next generation of district heating and cooling networks. Capable of operating at temperatures and pressures previously only achievable with steel systems, it offers outstanding thermal performance coupled with exceptional levels of reliability.

Hiline GRE dimensioned 800

Available Dimensions

(9m / 11.89m lengths)


GRE Service Pipe

Casing and Insulation
(Series 1)
Length Weight
  OD ID Wall Volume PN Casing OD Insulation thickness
  d   s     D (nominal)    
  mm mm mm l/m bar mm mm m Kg/m
HG.050.P20/9 56.8 53.2 1.8 2.22 20 125 32 9.00 3
HG.080.P20/9 85.4 81.8 1.8 5.26 20 160 35 9.00 5
HG.100.P20/9 109.6 105.2 2.2 8.69 20 200 42 9.00 6
HG.150.P20/9 165.6 159.0 3.3 19.86 20 250 39 9.00 9
HG.200.P20/12 217.4 208.8 4.3 34.24 20 315 45 11.89 14
HG.250.P20/12 273.5 262.9 5.3 54.28 20 400 59 11.89 17
HG.300.P20/12 326.3 313.7 6.3 77.29 20 450 58 11.89 24
HG.350.P20/12 358.2 344.4 6.9 93.16 20 500 67 11.89 30

Please Note: Pipes are supplied with factory-prepared taper spigot/socket ends.  Larger diameters, up to DN600mm, are available on request

Glass Reinforced Epoxy (GRE) Service Pipe

A composite pipe manufactured from helical-wound glass fibre reinforced epoxy material that is designed for use in heating and cooling networks. Offering a minimum life of 25 years when operating at 120°C at 10 bar, the service pipe will accommodate pressures of up to 20 bar and details of service life at other temperature and pressure combinations can be found on the table opposite.

Tough Outer Casing

Manufactured in HDPE to the requirements of the EN253 standards, the tough and resilient outer casing enables the pipe to be buried directly in the ground – so ensuring the network’s insulation integrity is maintained throughout its service life.

High-Performance Insulation

A layer of CFC-free rigid polyurethane foam provides outstanding insulation properties, with values of 0.022 W/mK and with the insulation thickness according to the Series 1 requirements of EN 253. With the service pipe and outer casing being bonded together by the foam insulation, the system far out-performs other systems with an air gap. With this increased efficiency, comes lower heat loss and therefore a saving in both operational costs and carbon emissions.
For even greater efficiency, Hiline GRE pipe systems are also available with increased insulation thickness to series 2 and series 3.

Complete System

Hiline GRE has a comprehensive range of pre-fabricated bends, tees, fittings and accessories that enable it to be adapted to meet all possible configurations – including transitions to other types of pre-insulated pipe systems – such as Hiline Steel or Hiline Flex. Hiline GRE can be offered as off-site pre-fabricated fittings and spool assemblies to meet a client’s bespoke requirements – significantly reducing installation time and cost.

Hiline GRE Joint Cutaway 400

Robust and Adaptable Joints

The Hiline GRE service pipe is joined by means of an adhesive-bonded taper socket and spigot technique that provides secure and reliable connections that will exceed the life expectancy of the pipe system. The HDPE outer casing can be joined using the proven Hiline range of wrap-around heat-shrink or electro-fusion couplings to ensure the very tightest of joints to protect against the ingress of ground water.

Trace Heating and Leak Detection Options

Hiline GRE is available with the option of integrated trace heating cables to protect the media temperate and leak detection systems that warn of moisture ingress into the insulation.


The GRE service pipe is manufactured in line with procedure ISO 14692; 1-4 and ASTM D 2310 class 11FX1 and ASTM D 2996, indicating type, grade, class and long term pressure strength classification for the GRE pipe axial load resistant type of pipe being RTRP-11 FW1.

Hiline GRE pre-insulated pipes and fittings for thermal utilities are manufactured within an ISO 9001 accredited environment, generally in accordance with the requirements of EN 253 and in compliance with EN 448, EN 488, EN 489 and EN 13941

Service Life

Hiline GRE  - Service Life

Water Temperature

Service Life (years)

Working Pressure (bar)

Up to 95°c





























* Contact us for details

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)