PIPE FREEZING
Liquid Nitrogen Pipe freezing
Liquid Nitrogen is applied to the external surface of the pipe, this transfers the low temperature of the Liquid Nitrogen (-196 deg C) through the pipe reducing the temperature of the fluid inside to below its freezing point and creating an “Ice plug”.
The amount of time taken to achieve a freeze is dependent upon many factors, primarily it is the size of the pipe and temperature of the contents although system conditions can be contributing factors.
Once a freeze has been achieved it is maintained by the continued application of liquid Nitrogen.
When we inform you it is safe to start work you can be confident in the knowledge that a freeze achieved using liquid Nitrogen can hold back over 275bar/4000psi, and you will be able to weld, cut, thread or grind without risk of the “ice plug” failing.
Pipeline materials that can be frozen include:
- Carbon steels
- Copper
- Lead
- Cast iron
- Stainless steel
- Epoxy coated pipes
- Concrete and asbestos
- Aluminum
Fluids that can be frozen include:
- Fresh water
- Glycol solutions
- Sea water
- Sewage
- Sludges
- Contaminated water
- Alcohol
- Crude oil
- Fuel oils
- Methanol
- Lubrication oils
Requirements
Generally we require the following conditions to be able to achieve a freeze
No fluid movement – To allow us to carryout a successful isolation we generally require no flow within the pipework, although if you have leaking pipework or fittings, or a low state of flow it may still be possible to freeze
Suitable length of pipework – To carryout the freeze we need a sound length of pipe with no joints or fittings, Depending on pipe size we can get a freeze on as little as 75mm.
Temperature of contents – It is possible to freeze hot pipes, we have frozen pipes from a starting temperatures of over 100 deg C, however as pipe size increases the temperature at which the contents can be frozen decreases. At 200mm/8″ or above we require the pipework and contents to be at no more than 40 deg C.
Information we require
Location
Size of pipe and contents
Number of freezes required
Temperature
Amount of time you require the isolation’s held for or the nature of your intended work.
