EN 15698-1:2009

Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Requirements
  4.1 General
  4.2 Steel service pipe
  4.3 Material, casing properties and
      dimensions
  4.4 Polyurethane rigid foam insulation (PUR)
  4.5 Pipe assembly
      4.5.1 End alignment of forward and
             return service pipes
      4.5.2 Distance between forward and
             return service pipes
      4.5.3 Twisting of service pipes
      4.5.4 Centre line deviation
      4.5.5 Pipe ends
      4.5.6 Axial shear strength
      4.5.7 Expected thermal life and long term
             temperature resistance
      4.5.8 Thermal conductivity in unaged condition
      4.5.9 Impact resistance
      4.5.10 Long term creep resistance and modulus
      4.5.11 Surface conditions at delivery
      4.5.12 Measuring wires for surveillance systems
5 Test methods
  5.1 General
  5.2 Test specimens
  5.3 Casing
  5.4 Polyurethane rigid foam insulation (PUR)
  5.5 Pipe assembly
      5.5.1 Axial shear strength
      5.5.2 Expected thermal life and long term
             temperature resistance
      5.5.3 Thermal conductivity in unaged condition
      5.5.4 Thermal transmittance
      5.5.5 Impact resistance
      5.5.6 Creep behaviour at 140 degrees C
6 Marking
Annex A (informative) - Guidelines for inspection and testing
Annex B (informative) - Calculation of thermal transmittance
Annex C (informative) - Waste treatment and recycling
Bibliography

This European Standard for District Heating Twin Pipes, specifies requirements and test methods for straight lengths of prefabricated thermally insulated pipe-in-pipe assemblies for directly buried hot water networks, comprising two steel service pipes from DN 15 to DN 250, rigid polyurethane foam insulation and one cylindrical outer casing of polyethylene. The pipe assembly may also include the following additional elements: Measuring wires, spacers and diffusion barriers.This standard applies only to insulated twin pipe assemblies, for continuous operation with hot water at various temperatures up to 120 °C and occasionally with a peak temperature up to 140 °C.The estimation of expected thermal life with continuous operation at various temperatures is outlined in Annex B of EN 253:2003.