THE STRUCTURE OF THE TUBING COUPLING IS
the tubing end and the inner wall of the coupling are connected by conical thread, and the tubing end of the coupling body is connected by flat thread with the same thread and pitch, which has the characteristics of relieving the stress concentration at the root of the external thread of the tubing connected by a single cone thread, and is not easy to produce fatigue and fracture, and the connection effect is good and effectively prevents the accident of the oil well string breaking.
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