| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a joint for an oil-well steel pipe which has superior sealing performance, even under a more severe working environment than before. SOLUTION: The joint for an oil-well steel pipe comprises a male member, having an annular surface provided to the tip side of a pipe body and an outer peripheral surface provided to the rear-end side, a female screw having a cavity, inside which the male member is accommodated and screwing on the male screw in the cavity, and a female member, having an annular surface making contact with and joint opposedly against the annular surface of the tip side, where the annular surface of the female member is provided with a recessed groove, in which a sealing ring is fitted and the load surfaces of the male and female screws are formed by a screw thread having a negative load flank angle.</p> |
