Pipe freezing kit removes draining time 09 July 2021

Companies facing system downtime can drastically reduce pipe and valve repair and maintenance costs with Accu-Freeze, available from the Pipestoppers division of Huntingdon Fusion Techniques. Many companies may have pipework systems such as sprinkler systems for example, that are full of water or other fluid that need to be completely drained for the smallest of repair.

Accu-Freeze works by reducing the pipe fluid to a temperature below its freezing point and developing a freeze plug. This controlled method of pipe freezing uses liquid nitrogen (LN2) to freeze stationary liquids in a section of pipe or tubing. The nitrogen is passed through a coil surrounding the pipe producing a frozen plug inside and hence preventing flow through the part to be removed.

The ice plug only forms beneath the Accu-Freeze coil wrap, jacket or aluminium clam jacket. The system is effective on ½ - 12" (150 to 300 mm) pipe or tube with specials available for larger diameters. The ice plug does not expand outside of the range of the jacket or coil.

Luke Keane, technical support at HFT said: “We carried out an installation of an Accu-Freeze System for a client who was contracted to repair pipework in large blocks of apartments. Working in the plant room, access was pretty tight as the pipes were only 6-8” from the ground. At one end of the pipe there was a pressure gauge and at the other, a 1,000 litre hot water cylinder. Ambient temperature in the pipe was approximately 38ºC.”

“We used a copper coil on the 2” 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 nitrogen (LN2). 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.”

The LN2 injections are automated, which reduces the operators’ workload and the amount of LN2 consumed, keeping operating costs low. Accu-Freeze can also be operated remotely, which makes it ideal for use inside ‘hot’ nuclear areas where personal exposure must be kept below certain limits.

Operations Engineer

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Huntingdon Fusion Techniques Ltd

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