The invention belongs to the technical field of pipeline hole opening under pressure, in particular to a hole opening tool under pressure and a hole opening process for a composite pipeline with a PE(
polyethylene) lining
pipe. A PE
pipe fitting with a pre-buried
electric heating wire, a PE
saddle and a PE
flange is used in the hole opening process. The construction process is characterized in that a
branch line hole opening method that holeopening is required to be connected with a
branch line without stopping and disconnecting the main pipeline after the pipeline is repaired by using the PElining
pipe is adopted, a part of the old pipeline is removed at the hole opening position, the prefabricatedPE
pipe fitting with the pre-buried
electric heating wire, the PE
saddle and the PE flangeis welded to the hole opening position of the PE lining pipe in an electric melting mode, a pipe hoop is installed to sleeve the PE
pipe fitting and the exposed part of the PE lining pipe at the old pipeline removal part, a
branch line valve is installed, the hole opening tool under pressure is installed, the
branch line valve is closed after the hole opening operation under pressure is finished,and the hole opening tool under pressure is disassembled. The newly-added
branch line hole opening of the composite pipeline with the PE lining pipe is realized through a non-stop conveying hole opening mode under pressure.