| 摘要 |
<p>PURPOSE:To withstand repeated use while having excellent airtight properties and high attachable/detachable torque. CONSTITUTION:Load surfaces of an external thread and an internal thread are brought in contact with each other in fastening, and one of a top surface 3 or a bottom surface 4 comes in contact with the load surface, while the other one has a clearance. Moreover the clearance of 0.03mm or less is made on the insertion surface 2 of the external thread and the internal thread. Thereby, the threaded joint can withstand the great number of repeated fastening and detachment and can be economically used even if the depth of the well is deep or the corrosive environment is hard.</p> |
