Abstract: An apparatus is used for both repair of operating pipelines and protection of newly built pipelines and comprises a cleaning tool (1) which is caused to move in the interior of the pipeline (5) under the action of a flow of fluid containing a dissolved inhibitor. The cleaning tool comprises a hub (3) on which blades (4) are secured in two rows to engage the pipeline surface. The blades (4) are displaced with respect to one another so that the angle between two adjacent blades is from 10.degree. to 25.degree. to define apertures along the periphery of the cleaning tool through which jets of fluid can flow to remove a part of deposits and to impregnate the remaining layer with the inhibitor dissolved in the fluid as so to form a protective coating. A support member (11) carrying an impact-type alarm member is mounted on the cleaning tool (1) so as to facilitate location of the apparatus in the pipeline and to maintain the apparatus in a desired position.