Metalloplastic flexible annular joint, wherein it comprises a first metal ring constituted by an inner metal spring with contiguous turns closed on itself and surrounding said spring, at least one metal envelope in which is embedded the spring, said envelope being extended by two parallel planar faces which extend in a transverse equatorial plane of symmetry of the joint, said faces having flared extensions moving away from said plane at a predetermined distance from the spring to partly surround a second solid elastomer plastic ring which is coaxial to the spring in such a way as to create between the two rings a sealed enclosure of limited volume which can be used for controlling the sealing of the joint.