A device for manufacturing a double-walled thermoplastic pipe with a connecting sleeve has a molding tunnel with a succession of molds for forming a corrugated molding wall and a connecting sleeve, respectively. An extrusion device extrudes a first flexible tube into said molding tunnel and a second flexible tube into said first flexible tube. A first gas channel is arranged for generating a pressure between said first and second flexible tubes. A compressed-gas control device is connected to said first gas channel for generating a pressure p1 or a pressure p2 in said space between said first and second flexible tubes by compressed air emerging from said first gas channel. A second compressed-gas control device is connected to a second gas channel for guiding compressed gas onto an inner side of said second flexible tube. Said first pressure controller is connected to said first gas channel via a compressed-gas line that is connected to an additional compressed-gas reservoir for gas exchange therewith.