Fremgangsmåte til fremstilling av innvendig pletterte rör

This invention concerns a process for producing internally plated pipes which, as compound pipes with an outer diameter of at least 60 mm, are used for transport of corrosive and/or abrasive fluids. To that effect, a second (inner) pipe (2) with a slightly smaller outside diameter than the inner diameter of an outer pipe (1) and a wall thickness of at least 1 mm is inserted into an outer pipe (1) of carbon steel or another more resistant metallic material. The inner pipe (2) is made out of another material, particularly of a corrosion resistant and/or wear resistant metal. Moreover, the outside pipe is reduced in diameter by forced fit using a reducing ring (4) so that the outer pipe (1) is mechanically reduced to press against the inner pipe (2). This invention is characterized in that the reduction of the diameter of the outer pipe (1) using a reducing ring (4) is only carried out to the extent that the mechanical deformation of the inner pipe, which is brought about by the pressing on of the outer pipe onto the inner pipe (2), still remains within the elastic range.