| 摘要 |
A tightening method for a special joint having unthreaded metal-to-metal sealing surfaces and unthreaded shoulder portions. By controlling the ratio of the tightening torque at the completion of tightening to the shouldering torque at the time when the unthreaded shoulder portions come into contact to be in the range of 1.25 - 20 and more preferably 1.4 - 10, sufficient gastightness can be guaranteed and plastic deformation due to overtightening can be prevented regardless of the type of pipe joint or the conditions of use. As a result, it can be widely utilized in the tightening of special joints used with oil well pipes even under the present state of increasingly severe oil well environments. <IMAGE> |
