Freezing Water Pipes
Why would a customer want to freeze a pipe? Well it is not freezing the entire length, it is creating a plug inside the pipe line to stop the water flow once a tap is opened, to then cut the pipe without shutting down the water supply.
A freeze plug will only be able to form on a pipe with no movement on that section or branch of water pipe, as long as there is no movement or flow, a plug will form.