Patent ID: 8220842
Filing Date: 2012-07-17
Classification: E21B,F16L

Abstract:
1. A threaded tubular connection for a tubular string that is subjected to dynamic bending loads, comprising: a male tubular element provided with a male threaded portion and a female tubular element provided with a female threaded portion, the male threaded portion and the female threaded portion each comprising self-locking threads having a crest, a load flank, a stabbing flank and a root, a load flank lead of the self-locking threads being larger than a stabbing flank lead of the self-locking threads such that in a tightened position of the threaded tubular connection, the load flanks and the stabbing flanks of the male self-locking threads are engaged in tight contact with the load flanks and the stabbing flanks of the female self-locking threads, and a transfer zone that is axially disposed between said threaded portions and a free end of at least one of said tubular elements, and that is axially spaced from said threaded portions, wherein a fraction of at least 20% of bending moment, to which the connection is subjected, is transferred from one of the male and female elements to the other, wherein the male and female elements include respective transfer surfaces in mutual contact with a radial interference fit in said transfer zone, at least one of the transfer surfaces being an undulated surface having a profile and defining a series of rounded annular ribs which come into interfering contact with the facing transfer surface, points of maximum diameter and minimum diameter of the profile being located on respective rounded portions of the profile, the free end of one of the tubular elements having a front surface free of contact with the other tubular element.