Abstract: A device for producing hollow plastic pipes having a predetermined wall thickness, includes an extruder for producing soft hollow plastic tubing from a raw material, a continuous cooling chamber disposed downstream of the extruder for hardening the soft hollow tubing into the desired plastic pipes after the wall thickness of the plastic tubing has been calibrated, an independent water cooled calibrating sleeve disposed between the extruder and the cooling chamber which adjusts the wall thickness of the soft hollow plastic tubing, the water cooled calibrating sleeve being separated from the extruder and the cooling chamber, and a thickness measuring device disposed in the gap between the calibrating sleeve and the cooling chamber. The calibrating sleeve has an inner wall in which are arranged water inlets and suction orifices distributed along the circumference and the length of the inner wall.