Threaded joint for steel pipes
AssigneeSumitomo Metal Industries, Ltd.
InventorsMasaaki SUGINO, Shigeo NAGASAKU
Life of this patent
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Abstract
The galling resistance of a threaded joint for steel pipes which satisfies the standards for an API round threaded joint and which has a pin with triangular male threads and a box with triangular female threads which threadingly engage with the male threads and an unthreaded sleeve positioned at the end of the box is improved. The unthreaded sleeve is shortened or removed so that the length of the unthreaded sleeve in the axial direction of the box becomes at most ½ (including 0) of the value specified by the above standards. The shape of the box specified by the above standards may be modified by providing a swoosh portion at the end of the box and/or by making the bevel angle at the end of the female threads ±15 degrees of the flank angle of the female threads.
Claims7
A threaded joint for steel pipes constituted by a pin and a box which can fit each other, characterized by differing from a threaded joint satisfying the standards for an API round threaded joint prescribed by the American Petroleum Institute in which the pin has triangular male threads and the box has triangular female threads which can threadingly engage with the male threads and an unthreaded sleeve in an opening end of the box in that the unthreaded sleeve of the box is at least partially removed such that the length of the unthreaded sleeve in the axial direction of the box is at most one-half of the value (including 0) prescribed by the above standards.
Dependencies are inferred from the claim text.