THREADED PIPE JOINT Russian patent published in 2014 - IPC F16L15/00 E21B17/02 

FIELD: machine building.

SUBSTANCE: invention relates to drilling equipment and refers to threaded joint of mainly drill and casing pipes. The threaded joint consists of two parts: a pin and a coupling forming one outer or outer and inner thrust junction, and comprises a recess made along the helical thread line on the nonoperating side of its profile, the recess has constant width and maximal depth in the beginning of the screw first to the junction. The proposed joint is distinguished by the fact that the width m of the base formed at making the recess of a protrusion adjoining the operating side of the thread profile, is determined by the formula m=S_w·k_a/π∙D, where: S_w - area of weak section of a joint part; k_a - coefficient considering the portion of axial force of joint tightening which falls to the thread turn nearest to the thrust junction; D - average diameter of thread of a joint part. Additionally the joint is distinguished by the fact that provided with the second inner thrust junction in it, the recess depth is of maximal value in the beginning of the first thread turn at each thrust junction of the joint and is decreasing to zero by the middle of the thread length.

EFFECT: all other things being equal, tightening torque of the proposed joint is significantly greater than that of a standard joint, so it provides for higher endurance limit and reliability at sign altering loads.

2 cl, 1 dwg, 2 tbl