An assembly including two symmetrically-disposed expandable threaded tubular joints. The joints including a male tubular element at one end of a tube and equipped with a male thread, a first annular lip having a first axially abutting surface, a first inner surface and a first outer surface, and a second abutting surface; and a female tubular element equipped with a female thread, a second annular lip having a third abutting surface, a second outer surface and a second inner surface, and a third inner surface and a fourth axially abutting surface which, together with the second outer surface, defines an annular housing homologous to the corresponding first lip. The two female tubular elements form two opposing ends of a female/female-type sleeve.