Abstract: A composite sleeve A serves as an impermeable coupling between pipes T1 and T2 having smooth, uniform ends. The sleeve comprises a rigid binding ring B acting as a jacket for a flexible, elastic and reversible collar C, which is attached to the binding ring by a pair of toric retaining rings D which press the collar C internally against the binding ring at zones of contact 13 in proximity to the ends of the binding ring, while creating, between the contact zones, an annular space 14 between the collar and the binding ring. The coupling connects collection pipes used for gravitational sanitary drainage, and is impervious to internal and external pressures.