Patent ID: 6030004
Filing Date: 2000-02-29
Classification: E21B,F16B

Abstract:
In a drill pipe tool joint having an internally threaded box section and an externally threaded pin section, the improvement comprising:(a) the box section having internal and external circular face shoulders and a tapered internal threaded section;(b) the pin section having circular shoulder surfaces having face to face engagement with said internal and external circular face shoulders of said box section when the tool joint is made up;(c) said box section and said pin section each having tapered equal angled threads having a thread flank angle in a range of 65.degree. to 85.degree. and being disposed in threaded interengagement when the tool joint is made up; and(d) said tapered equal angled threads having generally elliptical root surfaces for minimizing stress concentration, said generally elliptical root surfaces being defined by a large root radius and by a radius of intersection with adjacent thread flanks defined by radii smaller than said large root radius.