Connecting joint with special knuckle threads for oil casing

Abstract

The invention relates to a connecting joint with special knuckle threads for an oil casing, which comprises a coupling and a tube. The coupling and the tube are connected in a threaded manner, the special knuckle threads have arc tooth tops and arc tooth bottoms, and the thread side angle of a guiding surface of the special threads is different from that of a bearing surface; a middle cylindrical surface is arranged in the middle of the inner wall of the coupling, a metal sealing structure is arranged between each of two end surfaces of the middle cylindrical surface and an end of a tube, and each metal sealing structure comprises an inner sealing surface and an outer sealing surface; each inner sealing surface comprises an inner conical surface and a transitional conical surface, each inner conical surface is arranged between a corresponding end surface of the middle cylindrical surface and a corresponding inner threaded end of the coupling, and each end surface of the middle cylindrical surface is inclined outwards to form an inner end surface chamfer; and each outer sealing surface comprises an outer conical surface arranged on the outer wall of the corresponding end of the tube, and the end surface of the end of the tube is inclined inwards to form an outer end surface chamfer. The connecting joint comprises the asymmetrical special knuckle threads, is provided with the metal sealing structures, and is high in strength, sealing performance, anti-torsion performance and anti-bending capacity.

Description

technical field [0001] The invention relates to an oil well pipe thread joint used in the petroleum industry, in particular to a special round thread oil casing joint. 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 invention [0004...

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.

Images