Pre-installation of cold core for local frozen plugging of large diameter gas pipeline

The local frozen plugging technology with dumbbell-shaped cold core is presented to solve the existing problems in current welding-replacement operation of large diameter gas pipeline. The solid-water emulsifier is injected into the annular space between the frozen dumbbell-shape cold cores and internal wall of pipe, the oil and gas isolation can be realized when the solidwater emulsifier is stuck onto the internal wall of pipe at low temperature. Experiment results indicate that the technology can make the solid-water emulsifier, preset cold core and internal wall of pipe become a whole by making the solid-water emulsifier frozen by using additional cold source, and then the oil and gas within pipeline will be isolated at < 2.2 MPa. This method has higher safety with sound maneuverability.