About PipeFreezing
Put simply, pipefreezing is a non-intrusive, controlled method of isolating a short section of pipe, by solidifying the pipe contents to form a secure ice plug which in turn contains the liquid flow whilst a modification procedure is carried out. The major advantage is that a 'break-in' can be performed 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 introduced into the jacket to freeze the contents of the pipe. Liquid Nitrogen has a temperature of - 196°C, and is consumed 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 maintaining the plug in its frozen form, while replacement, maintenance or repair work takes place.
Once the ice plug is established, the 'dead-side' can be drained, thus allowing intrusive pipework repairs or alternations to be carried out. Once work is completed and the system back-filled, the integrity of the repaired section can be pressure tested to the ice plug.
The freeze process time varies, depending on the size of pipe and its contents. Hydrocarbon oils and other chemicals can take up to four times as long to freeze as water.
Download our brochure here: PipeFreezing Brochure
Sequence A
The redundant branch to be removed is clearly visible in the excavation. It was decided to freeze the 12" main either side of the branch to effect total isolation, in order to remove the redundant pipework and fit a blank flange.
Sequence B
The pipe has been cleaned of mud and loose dirt, the two pipefreezing jackets have been assembled around the pipe at their preferred locations, and the freezes have been achieved and pressure tested to ensure their integrity.
Sequence C
Once the freezes have been confirmed as 'ON' the branch is drained and removed. The flange was cleaned and the blank flange installed with a new joint ring and fastenings. The jackets were removed and the freezes allowed to thaw naturally.
