Threaded Joint

A threaded joint for coupling together first and second members, each of said members having a central axis between respective ends thereof, said joint comprising:

• a pin thread segment at one end of said first member;
• and
• a tubular box thread segment at one end of said second member, said box thread segment and said pin thread segment each comprising:
• a helical thread defined by a pressure flank and a clearance flank spaced apart from each other with alternating roots and crests extending between said pressure flanks and clearance flanks,
• wherein said pressure flank comprises an S-curve extending upward from the root toward the crest, said S-curve defined by a first curvature c1 adjacent to the root and a second curvature c2, c1 and c2 curving in opposing directions with an inflection point between said curvatures c1 and c2,
• wherein c1, c2, or both c1 and c2, comprises a first compound curvature, and
• wherein the clearance flank comprises a curvature c4 comprising a second compound curvature, the second compound curvature comprising a segment of a first circle having a radius R5, and a segment of a second circle having a radius R6.

A threaded joint part comprising:

• a body,
• a helical thread having a trapezoid profile and extending around the body, the helical thread having flat crests and flat roots, a pressure flank and a clearance flank spaced apart from each other with alternating roots and crests extending between the pressure flank and the clearance flank,
• the helical thread having a tapered leading section having a first end and second end, the first end starting proximate at an end of the body, the leading section tapered from the second end to the first end,
• an angular crest located between the second end of the tapered leading section and the flat crests.