Abstract: This mechanism offers a simple solution wherein an axial movement of a grooved piece (6) brings about a radial movement of rigid balls (5) that grip and deform a pipe (1) that is initially in a plastic state. Depending on the geometry of the channels (7) of the grooved piece (6), a variable grip is achieved. This gripping operation is simply released as the grooved piece (6) returns to its initial position, the pipe (1) itself now being in a solid state, so that the balls (5) are returned to their initial position. The correct position for gripping the plastic pipe can be detected by a detector (11). The pressurization of the plastic pipe can be achieved thanks to an elastic joint (10) on the piece that surrounds the pipe (1).