Threaded tubular element for fatigue resistant threaded tubular joint and resulting threaded tubular joint

摘要

In the present invention, there is disclosed a male or female threaded tubular element (1, 2) for a threaded tubular connection (10, 300) formed at the end of a pipe (101, 102, 202, 301, 302) and comprising an external male threading (3, 303, 303') or an internal female threading (4, 304, 304') depending on whether the threaded element is male or female in type, the threads of which (11, 12), viewed in longitudinal cross section passing through the axis of the threaded element, comprise a thread crest (17, 20, S1, S2), a thread root (18, 19, F1, F2), a rectilinear load flank (13, 14), a rectilinear stabbing flank (15, 16) and two tangential thread root junction zones (21, 22, 51, 52) each of these two zones being disposed between the thread root and one of the two flanks termed the corresponding flank and comprising an arc of a circle, characterized in that at least one of the two tangential thread root junction zones termed the "multiple radius zone" comprises an arc of a circle termed the principal arc (23, 24, 53, 54) where the support circle cuts the support straight line of the corresponding flank at a point termed the flank reference point (PiRF1, PiRF2, PiRF3, PiRF4), and a regular curve termed the secondary curve (25, 26, 27, 55, 56) on either side of the principal arc, which tangentially joins this to the corresponding flank on one side and to the thread root on the other and in that: a) at the flank reference point, the tangent (61, 62, 67, 68) of the support circle of the principal arc makes an acute angle (D, F), which is strictly positive with the support straight line of the corresponding flank, the positive sense being such that the principal arc does not cut into the material of the thread flank; b) said support circle of the principal arc cuts or is tangential to the support straight line of the thread root, the tangent to said support circle (63) making, at the intersection point (PiRR1) or at the tangent point under consideration, an angle (E) in the range -15 to +15[ degrees with the support straight line of the thread root.