Abstract: A fatigue resistant waisted threaded tubular element for threaded tubular connection, and resulting threaded tubular connection. The threaded tubular element is waisted by a groove formed in the material beneath the threading to reduce the stiffness of the wall at the level of the first engaging threads. The groove can prevent an increase in the transfer of tensile loads at the level of the first engaging threads of the threaded element on which it is formed and on the corresponding last engaging threads of the mating threaded element intended to be connected thereto to form a threaded tubular connection. This improvement in load transfer limits the risk of initiating a fatigue crack in threaded tubular connections subjected to a cyclic load without reducing their static performances.

Abstract: The threading of a threaded tubular element includes at least one tangential multiple radius junction zone at the thread root, in particular on the load flank side. This zone include a principal arc with a radius where the support circle cuts the flank at a point. The tangent to this circle makes a strictly positive angle with the flank. The secondary arcs have lower radii that effect the tangential junction of the principal arc on one side to the flank and on the other side to the thread root. The radius of the principal are larger than that of the standard circle which passes through and which would alone constitute a tangential junction zone. Such a threaded element provides a threaded tubular connection which incorporates good resistance to both static and cyclic stresses.

Abstract: The threading of a threaded tubular element comprises at least one tangential multiple radius junction zone (21) at the thread root, in particular on the load flank side (13).