Diagnostic protocol for thermal performance of district heating pipes in operation. Part 2: Estimation of present thermal conductivity in aged pipe insulation
Artikel i vetenskaplig tidskrift, 2021

Buried and operating district heating (DH) pipes are exposed to thermal degradation of their polyurethane (PUR) insulation over time, and their status is hard to 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 with numerical simulations of the temperature decline in drainage valves and shutdown valves. The drainage valve measurements were used to thermally assess part of a buried DH network. Results indicate that by using the drainage valves as measurement points in a cooling method, the thermal conductivity of the buried DH network could be predicted with an accuracy of >95%. In addition, a general diagnostic protocol has been established for assessing the thermal status of a DH network, ready for network owners to use.

Heat losses

Non-destructive testing

Cooling method

District heating network

Thermal status


Thermal conductivity



Peter Lidén

Chalmers, Arkitektur och samhällsbyggnadsteknik, Byggnadsteknologi

Bijan Adl-Zarrabi

Chalmers, Arkitektur och samhällsbyggnadsteknik, Byggnadsteknologi

Carl-Eric Hagentoft

Chalmers, Arkitektur och samhällsbyggnadsteknik, Byggnadsteknologi


1996-1073 (ISSN) 19961073 (eISSN)

Vol. 14 17 5302



Bearbetnings-, yt- och fogningsteknik

Annan fysik



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