Freezing District Heating Water

16th September 2021

  1. Case:

A while ago we got in touch with a new department of one of our customers which is in charge of some pilot projects in district heating water in Flanders. They had already taken their district heating installation into service for a new industrial site. As an expansion of the site was necessary they contacted us to inform if it was possible to extend their network on a dead-end without taking it out of service.

  1. Solution

As OPS we were capable of supplying different solutions to perform the intervention of which we chose to freeze the feed and return district heating water pipes DN40. This decision was taken because there would be no flow in the dead-end  and wall thickness for welding a linestopp fitting was limited.

  1. Job execution

Together with our customer and a partner we managed to make this a one day intervention.
We started the intervention by venting the pipeline so there was no air which could affect the freezing process. Once vented the temperature at freezing positions was about 70°C. OPS operators started the freezing intervention using liquid nitrogen expansion. After a while we managed to get the pipe completely frozen which we double checked with both temperature control and venting the pipe again.

Customer performed their network expansion welding intervention during OPS freezing supervision and the job was completed in only a few hours.


  1. Feedback:

Chosing freezing over linestopp was truly the best solution for this application. The district heating department was statisfied with the OPS provided solution and concluded the intervention was an effictive solution worth repeating.