The process of Pipeline Isolation

Pipeline isolation or Pipe freezing is a non-obtrusive, controlled method of isolating a small section of pipe, by solidifying the pipe contents to form a secure ice plug which in turn contains the liquid flow whilst a modification process is carried out. The main advantage of pipeline isolation is that a 'break-in' can be done without incurring the costs and down-time of a complete system drain down.

During the process, a jacket is fitted around the pipeline on either one or both sides of the work section and liquid nitrogen is inserted into the jacket to freeze the contents of the pipe. Liquid Nitrogen has a temperature of -196°C, and is utilized during the course of operations by continuous evaporation, which takes place within the jacket in three ways:

•  Heat is absorbed from the pipe and its' contents, as it cools from ambient temperature to liquid nitrogen temperature.

• By absorption of heat from within the jacket, and in natural evaporation through exposure to natural air.

• In managing the plug in its frozen form, while replacement, maintenance or repair work takes place.

Once the ice plus is placed, the inactive side can be drained, this enabling obtrusive pipe work repairs or modifications to be carried out.