DS EN 15698-1:2009 District Heating Pipes - Preinsulated Bonded Twin Pipe Systems For Directly Buried Hot Water Networks - Part 1: Twin Pipe Assembly Of Steel Service Pipe, Polyurethane Thermal Insulation And Outer Casing Of Polyethylene Provides 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