Huntingdon makes a clean cut with its Accu-Freeze System
Huntingdon Fusion Techniques has used its Accu-Freeze System to safely sever a wastewater pipeline as part of a project in Oregon. Accu-Freeze uses liquid nitrogen to create a frozen plug in the pipe before it is cut.
Liquid nitrogen is fed to a spiral copper tube wrapped around the target area to create an in-line ice plug capable of withstanding over 2,000 psi of pressure in pipes up to 12 inches in diameter. For larger diameters an insulated aluminium jacket is tailored to the job and placed around the target pipe.
While traditional liquid nitrogen freezing techniques needed large quantities of expensive liquid nitrogen, Accu-Freeze’s controller has cut nitrogen usage by developing a patented temperature monitoring and control system. Liquid nitrogen is pulsed into the spiral at the lowest possible rate, controlled by thermocouples placed around the freeze.
The Accu-Freeze System was developed for the nuclear industry in the US by two engineers at Diablo Canyon, who wanted a system that could be operated remotely, and which operated within tight cryogenic temperature limits for steel piping. Accu-Freeze has a long list of nuclear power and nuclear engineering customers, including General Dynamics’ Electric Boat submarine yard.
“Automatic control of the nitrogen flow frees people to do other work during the freeze, which in many situations can take hours,” said Huntingdon representative Michaela Reay. A freeze can be maintained for many days to allow engineers to work on the target component (usually a valve).
Accu-Freeze has already been used in hydrocarbons processing. Many hydrocarbons are hard to freeze and so in some cases water or water based gels are injected to create a viable freeze-plug zone.