Weld purging innovators, Huntingdon Fusion Techniques (HFT®), has created a pipe freezing system which enables repair work to be carried out on major pipe networks without having to drain the entire system.

The Accu-FreezeTM Pipe Freezing System utilises liquid nitrogen (N2) to freeze selected liquid in a specific section of the pipe or tube, which then safely forms a controlled, in-line ice plug, blocking the flow of fluid.

The contained ice plug, ideally situated upstream from the repair zone, forms beneath the Accu-Freeze jacket or coil and is capable of withstanding 138 bar in pipes or tubes with diameters of up to 12 inches.

Accu freeze paf pho 49 c frozen clam on pipe hft huntingdon fusion technique hft pipe

The UK-based business highlighted the primary advantages of the patented technique, quoting increased freezing capability of liquid N2 and the ability to control the pipe wall temperature throughout the freeze process. Accu-Freeze can be operated remotely with the liquid N2 injections automated throughout the entire freezing process.

Luke Keane, Technical Support at HFT, gave an example of the Accu-Freeze System being installed recently in Serbia, for a client who needed to repair pipework in a large apartment block, “We used a copper coil on the carbon steel pipe and had to wrap it about 10 inches along the pipe length, wound tight.”

“We then performed a freeze using the Accu-Freeze System connected to a dewar of liquid N2. Within 50 minutes a solid ice plug had been formed, blocking the flow from the cylinder to enable the pipe section to be cut out and replaced. Following the repair work, the ice plug defrosted naturally and the flow continued in the system. Minimum disruption, no system drain down, no air locks and extremely quick!”