A female element (1) includes a hollow internal body (2) having an end (3) provided with fastening device (5) to one of the pipes to be joined, a hollow external body (7) coaxial with the internal body (2) and having an end (8) which axially protrudes with respect to another end (4) of the internal body (2) opposite to that provided with the fastening device (5), one rigid central stem (9) coaxially supported by the internal body (2) by a transversal perforated base (18) and having a widened end (10) near the protruding end (8) of the external body (7), an axially sliding sealing bush (12) coaxially arranged about the stem (9) and elastically stressed to be engaged with the widened end (10) of the stem (9) to prevent the passage of fluid within the female element (1), a cleaning bush (14) coaxially arranged about the sealing bush (12) and axially stressed in position so as to prevent the entrance of dirt about the sealing bush (12) and a lock sleeve (16) arranged about the protruding end (8) of the external body (7) and engageable with a complementary end of a male element to ensure the stable union of the two male and female elements of the fitting. The stem (9) is fixed to the base (18) by at least one half bush (25) radially fitted and axially locked in corresponding seats (26, 27) of the stem (9) and the base (18).