US 5,092,635 A · Buttress thread form

Abstract

The overall description of this invention is a truncated buttress-type thread form that incorporates a reverse-angle tension load flank with a compression flank and a torque shoulder; the thread does not have any radial interference designed into it, but the hooked tension flank does tend to pull the pin and box together once the torque shoulder is engaged. The mating compression flanks have designed into them a minimum amount of clearance prior to the shouldering action, which then closes to zero or very near zero at the moment the shoulder is engaged. This drawing together is due to the tendency of the hooked threads to pull together at shouldering if there exists no radial interference in the thread body. The thread roots and crests can be tapered, parallel to the taper of the thread body, or flat and parallel to the pipe axis but maintain adequate clearance to allow some closure once the shoulder is engaged so that the compression flanks can draw together.

Claims14

Dependent claims

A thread form for a joint connecting two pipes comprising:

a pin having a root, a crest, a compression flank on one side of said pin root, and a tension flank on the other side of said pin root;
a box having a root, a crest, a compression flank on one side of said box root, and a tension flank on the other side of said box root;
said pin crests overlapping in part said pin roots;
said box crests overlapping in part said box roots;
a torque shoulder on said pin;
a torque shoulder on said box;
whereupon torquing the joint beyond initial contact between said box and pin torque shoulders, said pin and box tension and compression flanks are in respective contact over at least a portion of the length of the thread form such that compressive loads on the pipes are transferred substantially through the thread form rather than said pin and box shoulders;
said box crest is spaced from said pin root when the joint is torqued beyond initial contact of said pin and box torque shoulders;
said pin crest is spaced from said box root when the joint is torqued beyond initial contact of said pin and box torque shoulders;
and
wherein said box crest is longer than said pin root.

8 more elements

Dependencies are inferred from the claim text.

Buttress thread form

Life of this patent

Buttress thread form

Life of this patent

Abstract

Claims14