Abstract: A method of obtaining a leakproof connection between a metallic tube having a leak and a metallic sleeve extending over the leak, includes expanding the sleeve being formed of a material having given strength values against an inner wall surface of the tube being formed of a material having strength values greater than the given values. In order to bridge a gap due to spring-back without the aid of an additional component of a shape memory alloy, a sleeve material having strength values lower than those of the material of the tube is used. A leakproof connection is obtained as the result of the greater spring-back of the tube.