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Hiline Custom - Bespoke Pre-insulated Pipes

A pre-insulated system with a choice of service pipes and casing materials to suit the widest variety of applications


Hiline Range 200

Manufactured in accordance with BS EN 253, this rigid, bonded pre-insulated  pipe system is suitable for a variety of  applications - temperatures up to 95°C continuous. Available in dimensions ranging from 20mm to 250mm OD and supplied in 6 and 12 metres lengths.


The list of applications that are suitable for  Hiline Custom 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
  •  Hot Water
  •  Underground heating and HWS mains
  •  Corrosive chemical pipes
  •  Above ground heating and HWS mains
  •  Geo-thermal water pipes
  •  Process fluid pipes
  •  Secondary refrigerant pipes
  •  Temperature-sensitive product lines

Manufacture and Standards

Pre-insulated pipes and fittings for thermal utilities are manufactured within an ISO 9001 accredited environment in accordance with EN 253, EN 448, EN 488, EN 489, EN 13941

Service Pipes

Hiline Custom is available with a choice of a wide range of  pipes, including (but not limited to): PP-R, PP-RCT, PP-B, PP-H, ABS, PVC, PVDF, PE100, FRP and service pipes of other thermoplastic materials. It is commonly supplied with CPV Chemflo polypropylene manufactured from beige grey (RAL 7032) polypropylene block copolymer (PP-B) to dimensions and tolerances as specified in ISO 15494:2003. The quality standards and testing regime for the pipe are to DIN 8078 (Type 2 (PP-B)):1994 with the pipe having high impact resistance at sub-zero temperatures.

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
  •  Different thicknesses available (Series 1, 2 and 3)
  •  Available with optional trace or maintained heating cables
  • Thermal conductivity coefficient 0.022 w/mK

Casing Pipes

Casing pipe is manufactured in accordance with standard EN 253 from high density polyethylene (HDPE). Barrier casings are also available for applications in contaminated ground.


  •  Density 950 kg/m³
  •  Upper yield stress 19 MPa
  •  Elongation at break at least 350%
  •  Expected life at least 50 years

HDPE casing is also available with additional UV stabiliser offering greater protection against direct sunlight for above ground installations and with a barrier casing for use in contaminated ground.

Site Jointing Techniques

Service Pipes

In the case of Faser PP-R pre-insulated pipes to be installed in above and below ground thermal utilities,  the following techniques for thermoplastic welding can be used:

  • Socket fusion in accordance with DVS 2207 Part 11
  • Butt fusion in accordance with DVS 2207 Part 11 and ISO 12176-2 Part 1
  • Electrofusion in accordance with ISO 12176-2 Part 2

Casing pipes

The sealing of HDPE casing pipes in the field can be carried out using the following techniques:

  • Heat shrinkable HDPE oversleeve sealed with hot melt adhesive and heat shrinkable bands (Types NT & DSJ)
  • Heat shrinkable crosslinked HDPE oversleeve sealed with hot melt adhesive (Type TS)
  • Wrap around HDPE electrofusion coupling forming a fully fused casing joint (Type DX)
  • Slide over HDPE heat shrinkable oversleeve sealed by the electrofusion technique (Type DT) 

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. 

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)