| 摘要 |
A tubular connection employing two separate non-concurrent threaded sections, each of which nearly decays, that is, runs out on a tubular surface, one on the outside diameter of the male tubular member, and one on the inside diameter of the female tubular member, thus providing a joint with nearly the strength of the tubular body in tension without the use of a coupling. The female tubular member is expanded through a cold swaging operation before being finished with the two threaded sections. Additionally, the connection features a torque stop and cylindrical seal in the middle of the two thread steps, where stresses may be kept low. The thread elements are reverse angle locking with S-shaped load flanks which reduce stress concentrations and provide a clamping action on the centralized seal. Because of this unique seal, the connection can take cyclic application of external and internal pressure without leaking, a feat non-coupled and non-upset connections of prior art have not achieved. This invention is a total optimization of tension efficiency, pressure integrity, and low stress compared to all other connections of its genre.
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