Welding of conduit systems

Production of a pipe system (1) comprises connecting half shells (2a, 2b) by resistance welding, especially capacitor discharge welding. An independent claim is also included for a pipe system produced by the above process. Preferred Features: The longitudinal edges (3a, 3b) of the half shells have no annular projection. At least one half shell has an annular projection along its longitudinal edge which melts during joining of the half shells.