Abstract: A detachable plug assembly for making a connection between a pipe and an external unit such as a hose fitting or hydraulic unit, for example, in which the pipe can be automatically locked in a well-defined axial position in a bore of the external unit, and thus be assembled in a short time on an assembly line, particularly in the case of assembly by robots, without requiring special tools for either assembly or disassembly. The assembly comprises a bushing which is mountable in a fixed axial position on the pipe, the bushing having a conical shoulder at a forward end thereof for axially engaging the bore of the external unit and centering the pipe therein. The external unit has slots through which project the free ends of a locking element. The free ends extend into the bore of the external unit and engage a groove in the bushing for retaining the pipe in the bore of the external unit.