Abstract: For the connection of two tubes (1, 2), one coupling piece (3, 4), consisting of an external thread (7) adhered, vulcanized or fused onto the end of the tube and a pipe coupling (8) screwed onto this by means of a slide adhesive is each connected with the tube ends. By means of the one coupling piece (4), a coupling lock (5) is slid from behind, which, by means of a flange (12), abuts on a shoulder unit (11). On the free end, the coupling lock (5) supports two swivelable levers (15) with eccentric cams (16), which abut on the shoulder unit (10) of the other coupling piece (3) and press this axially against the first coupling piece (4). By means of this construction, a non-tapered cross-sectional area is achieved in the tube coupling.