Non-destructive methods for assessment of district heating pipes: a pre-study for selection of proper methods

Many energy companies are facing renewal of their district heating and cooling (DHC) network. However, there are no non-destructive methods to determine the performance of existing pre-insulated pipes during operation. A pre-study has led to a selection of a couple of non-destructive methods that will be further evaluated and tested in field and in laboratory. Two non-destructive methods, individually or in combination, are considered interesting for further studies. A cooling method and a method for evaluation of the temperature coefficient of resistance (TCR), which aims at using the existing copper wire in pre-insulated pipes.