Patent ID: 7014223

Claim:
A flush-type integral threaded joint for tubes, comprising a male member ( 1 ) provided, on its outer surface, with a frustoconical threaded portion ( 7 ) and a female member ( 2 ) provided on its inner surface with a frustoconical threaded portion ( 8 ), said respective two frustoconical threaded portions ( 7 , 8 ) of said male ( 1 ) and female ( 2 ) members having the same value of conicity, comprising between 6.25% and 12.5%, and being designed to screw together in a reversible way, one inside the other, until contact is produced between two pairs of annular shoulders ( 5 ′, 6 ′, 5 ″, 6 ″) lying substantially in a plane orthogonal to the longitudinal axis of said male and female members ( 1 , 2 ), each of said male ( 1 ) and female ( 2 ) members being provided with a pair of sealing surfaces ( 11 ′, 12 ′; 11 ″, 12 ″) respectively set adjacent each end of said respective frustoconical threaded portions ( 7 , 8 ) and with functions, in the first case, as an external seal ( 12 ′, 12 ″) and in the second case as an internal seal ( 11 ′, 11 ″) wherein a first surface of each of the two pairs of sealing surfaces ( 11 ′, 12 ′; 11 ″, 12 ″) is of a spherical shape and wherein each pair of sealing surfaces ( 11 ′, 12 ′; 11 ″, 12 ″) is adapted to operate under reciprocal radial interference of the correspondent sealing surfaces to provide a flush-type threaded joint.