TUBULAR THREADED JOINT WITH TRAPEZOID THREADS HAVING CONVEX BULGED THREAD SURFACE

摘要

The invention concerns a tubular threaded joint comprising two male and female threaded elements one screwed into the other with a specific torque wherein at least one thread surface under contact pressure (125) has prior to being screwed a continuous convex bulged shape over its bending radius length ranging between 2 and 60 mm and is in point-to-point contact with the corresponding surface (26) of the conjugate element. Such a threaded joint exhibits enhanced screwing and unscrewing strength. In one embodiment, the convex bulged surface (125) is a male or female thread flank and one of the male or female threads comprises a groove (31) emerging at the thread crest (29) to make, as the case may be, either the convex bulged flank (125) or the corresponding flank flexible. Such a geometry enables to accommodate contact variations between the flanks.