Diagnostic Protocol for Thermal Performance of District Heating Pipes in Operation. Part 2: Estimation of Present Thermal Conductivity in Aged Pipe Insulation

Buried and operating district heating (DH) pipes are exposed to thermal degradation of their polyurethane (PUR) insulation over time, status is hard assess without excavation. By using DH pipe valves in manholes as measurement points during a shutdown with an ensuing cooling period, non-destructive assessments can be performed. This study compares new improved field measurements numerical simulations the temperature decline drainage valves. The valve were used thermally part buried network. Results indicate that by method, conductivity network could predicted accuracy >95%. In addition, general diagnostic protocol has been established for assessing network, ready owners use.