| 摘要 |
A screw joint for oil well pipes, for preventing degradation in gastightness caused at the time of tension after axial compression, and a method of manufacturing the same. A screw joint for oil well pipes, formed with a seal portion and a torque shoulder portion, is such that a length (15) of a tip end of a thick-walled pin portion having an inner diameter determined by the formula (1) is not less than a length (16) extending to a position of the pin portion corresponding to the seal portion but not more than a half of a length (17) of the pin portion, an inner diameter of the remaining pin portion near a pipe body is equal to that of the pipe body, an inner diameter increases gradually from the thick-walled pin portion to the remaining pin portion, and an inner diameter of a box portion on the torque shoulder portion is equal to that of the tip end of the thick-walled pin portion in a state where the joint is fastened. Formula (1) is: do > dx ≥ d0 -, where dx (mm) designates a inner diameter of the thick-walled pin portion, and d0 (mm) designates an inner diameter of the pipe body. <IMAGE> |
