An improved process for cleaning the interior of a conduit having a series of straight sections and bends. The process includes passing a transit line having a multiplicity of flow divertors positioned at intervals along the length thereof through said conduit. By injecting a propelling gas stream having cleaning particles entrained therein, the multiplicity of flow divertors serve to enhance the in-situ cleaning action of the particles while the propelling gas stream serves to activate the flow divertors and cause the transit line to move along the straight sections and around the bends of the conduit.