One answer to this problem is pipe freezing..... Freeze the liquid upstream or on both sides of the repair zone, making a solid, high pressure resistant ice plug.
These high-pressure resisting, long life ice plugs can be made by Qwik-Freezer™ and Accu-Freeze™ systems available from HFT®.
What is pipe freezing?
Liquid carbon dioxide or liquid nitrogen is used to freeze stationary liquid in a selected section of pipe or tubing, accurately and safely creating an in-line ice plug.
This continually isolates the liquid in the system while repairs or modifications are carried out.
What pipe freezing kits are available?
Qwik-Freezer™ - for freezing water with liquid carbon dioxide.
Qwik-Freezer™ uses specially designed jackets, which are wrapped around the pipe at the point or points where the freeze is required. A nozzle on the jacket is coupled to a cylinder of liquid CO2 by means of a special hose.
When liquid CO2 is injected into the space between the jacket and the pipe, it immediately expands to form a solid carbon dioxide (dry ice) at a temperature of -70ºC (-108ºF). This low temperature quickly freezes the water inside the pipe, forming a secure ice plug beneath.
Accu-Freeze™ - for freezing liquids that have a lower freezing point than water by using liquid nitrogen.
For small diameter tubes and pipes, jackets as mentioned above can be used.
For diameters over 8”, it is possible to wrap copper tubing around the pipe where the plug is to be made instead of using jackets.
In addition for the larger diameter pipes, aluminium shells are available to fit precisely on the pipe, where the freeze is to be carried out.
Once the copper piping, jacket or shell have been added to the pipe, the LN2 is then injected via the Accu-Freeze™ control system which takes over by automatically injecting the LN2 and freezing to a temperature set by the user.
As with the jackets, the ice plug is formed directly below tube or shell.
If you have every tried to make a freeze with a spray can or an electric system, you will find that the Qwik-Freezer™ and Accu-Freeze™ systems are several dimensions higher in speed, cost saving and capability.
