THREADED JOINT FOR STEEL PIPES

摘要

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.