The invention relates to an intervention method for acting on the wall of a fluid pipeline by using a tool comprising a pipe segment and at least first means for creating sealing and second means for creating sealing, the method comprising a step of moving the tool inside the pipeline until the pipe segment is positioned facing a zone of the wall of said pipeline, the method further comprising a step of creating sealing upstream and downstream from said zone respectively by using the first and second means for creating sealing so as to seal off an outer portion of a segment of the pipeline around said zone, followed by a step of acting on said zone of the wall.