Line freezing is another means of isolating system components and or providing a means of pressuring testing pipelines. As provided by several specialized maintenance companies, a line freeze plug is performed by installing a jacket around the pipe and injecting liquid nitrogen. As the line cools, the process fluid transfers heat to the liquid Nitrogen, as the fluid cools it forms a solid plug. Once the plug is formed and is grown to the desired length, the system is ready to have the desired work performed. As long as the Nitrogen supply continues to the jacket, the freeze plug can be maintained. Line Freezing can be performed on various piping materials including carbon steel, cast iron, nickel alloy, aluminum alloy, copper-based alloy, and stainless steel. Line freezing is completed without the need of line stop fittings or welding.