Special round threaded joint of oil casing

Abstract

The invention relates to a special round threaded joint of an oil casing, which is applied to the oil industry and comprises a coupling and a tube. The coupling is connected with the tube via threads 4, the threads 4 are special round threads with arc tooth tops and arc tooth bottoms, a thread side angle of a guiding surface of the threads ranges from 40 degrees to 50 degrees, a thread side angle of a bearing surface of the threads ranges from 1 degree to 5 degrees, and the taper of the threads ranges 1:8 to 1:20. The special round threaded joint comprises the asymmetrical special round threads, the thread side angle of the guiding surface of the threads is larger than that of standard round threads, the screwing performance of the threads is good, and unaligned screwing is not easy to be caused when in tightening. The thread side angel of the bearing surface of the threads forms a barb, the connection strength of the threads is improved, the sealing performance of the threads is improved, simultaneously, bending resistance of the joint is realized, and the anti-leakage performance of the special round threaded joint is greatly improved.

Description

technical field [0001] The invention relates to a threaded joint of an oil well pipe used in the petroleum industry, in particular to a special round threaded joint of an oil casing. Background technique [0002] The oil and casing in the oil well pipe industry is mainly connected by threaded joints to form an oil and casing string with a length of several thousand meters. Among them, the strength requirements, sealing performance, tensile load and torque resistance of the threaded joint connection Higher requirements. [0003] At present, the structure of the existing oil-casing round thread connection is basically the API (American Petroleum Institute) standard round thread. The technology is relatively mature, but the use effect is not ideal. This kind of standard round threaded joint has poor sealing surface performance and weak bending resistance, which often leads to quality accidents such as leakage, breakage, and slippage at the threaded joint. Contents of the inv...

AI Technical Summary

Problems solved by technology

[0003] At present, the existing oil casing round thread connection structure is basically API (American Petroleum Institute) standard round thread, the technology is relatively mature, but the use effect is not ideal

This kind of standard round thread joint has poor sealing surface performance and weak bending resistance, which often leads to quality accidents such as leakage, breakage, and slippage at the threaded joints.

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