Sealing screwed joint

Abstract

The utility model discloses a sealing threaded connector which comprises a coupling and a pipe body meshed with the coupling, and the pipe body is connected with the coupling through threads. An external thread, an outer sealing surface and an outer shoulder surface are sequentially arranged on the upper surface of the pipe body from the middle part to the end part; an internal thread, an inner sealing surface and an inner shoulder surface are sequentially arranged on the lower surface of the coupling from the end part to the middle part; the external thread is matched with the internal thread, the outer sealing face is matched with the inner sealing face, and the outer circular bead face is matched with the inner circular bead face. The threaded connector has reliable connection strength and sealing performance under the complex working conditions of internal and external pressure, bending load, compression load, tensile load and the like.

Description

Technical Field

[0001] The utility model relates to the technical field of threaded joints, in particular to a sealing threaded joint. Background Art

[0002] API threaded joints are mainly sealed by threads, while special threaded joints achieve multi-level sealing through independent sealing surfaces and torque shoulders, while the threaded part mainly serves as a connection. Compared with API standard threaded joints, special threaded joints have significantly enhanced sealing performance and connection strength. Research on special threaded joints mainly focuses on analyzing the sealing performance, connection strength, mechanical behavior and deformation failure of thread segments, sealing surfaces and shoulders under loads such as thread loading and unloading, axial loads, internal and external pressures, bending moments and temperature.

[0003] In the oil and gas industry, the use of pipes is very large. The threaded part of the pipe is the weakest and most important link in the entire pipe connection, and is the core and key part of the pipe. As my country's oil production environment becomes increasingly harsh and the intensity of high-temperature and high-pressure oil and gas well production continues to increase, the stress and deformation problems of the pipe thread tooth surface have become more complicated, and the problems of leakage, slipping threads, and fractures caused by thread failure have become increasingly prominent, seriously affecting oil and gas production under various working conditions. In particular, the requirements for sealing performance in oil and gas production are getting higher and higher, and the development of pipe joints with excellent sealing performance has become a focus of attention.

[0004] At present, the existing special thread sealing surface structural features are: the sealing adopts a simple structure of cone face to cone face or spherical face to cone face; it is easy to process and measure, and the technology is relatively mature. The disadvantage is that the seal is easy to separate under complex loads underground, and the bending resistance is weak, which often leads to leakage, breakage, slippage and other quality accidents at the threaded connection parts. Utility Model Content

[0005] In order to overcome the defects of the above technologies, the purpose of the utility model is to provide a sealed threaded joint, which effectively solves the defects of threaded joint sealing failure and joint disengagement, and improves the threaded joint under complex working conditions such as internal and external pressure, bending load, compression load and tensile load. The connection strength and sealing performance have more reliable.

[0006] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0007] A sealed threaded joint comprises a coupling 8 and a pipe body 7 meshed therewith, wherein the pipe body 7 is connected to the coupling 8 through threads;

[0008] The upper surface of the tube body 7 is provided with an external thread 4, an external sealing surface 5, and an external shoulder surface 6 in sequence from the middle to the end;

[0009] The lower surface of the coupling 8 is provided with an internal thread 1, an internal sealing surface 2, and an internal shoulder surface 3 in sequence from the end to the middle;

[0010] The external thread 4 matches with the internal thread 1 , the external sealing surface 5 matches with the internal sealing surface 2 , and the external shoulder surface 6 matches with the internal shoulder surface 3 .

[0011] The end of the pipe body 7 is provided with an external thread 4, and both ends of the coupling 8 are provided with an internal thread 1. The thread taper 12 of the pipe body 7 and the coupling 8 as a whole is 1:16, which can ensure high connection strength.

[0012] The outer sealing surface 5 is provided with a section of arc surface structure; the inner sealing surface 2 is provided with a section of inner sealing arc surface, and the inner sealing surface 2 and the outer sealing surface 5 are interference fit to form a main sealing surface.

[0013] The pipe body 7 is provided with an inwardly concave reverse end face A with a reverse angle of 15°, and the coupling 8 is provided with a shoulder surface, and the reverse end face A and the shoulder surface cooperate to form a secondary sealing surface. The threaded joint for the oil pipe adopts an improved partial trapezoidal thread, and the threaded joint connection for the casing adopts an industrial standard partial trapezoidal thread, and the thread surface is filled with thread grease.

[0014] The tooth height (h2) of the internal thread 1 is 1.7-1.9 mm, the tooth height (h1) of the external thread 4 is 1.6-1.7 mm, and the gap size is 0.15-0.25 mm.

[0015] The internal thread 1 and the external thread 4 include a guide surface angle 9, a load surface angle 10 and a pitch 11. The guide surface angle 9 is 15°, the load surface angle 10 is -5.5°, and the pitch 11 is 6 threads per inch; the thread taper 12 is 1:16, and the torque shoulder angle A is -15°, which ensures the buckle positioning and plays a role of auxiliary sealing.

[0016] Beneficial effects of the utility model:

[0017] The utility model adopts the outer sealing arc surface and the inner sealing structure to form a match, thereby improving the axial tensile strength and ensuring the reliability of the nose metal seal, and enhancing the anti-slip performance.

[0018] The torque shoulder and the end of the pipe column are equipped with an arc-shaped sealing surface, which reduces the tensile, compressive and bending loads on the joint, thus achieving excellent sealing performance. The design of the reverse shoulder of the secondary sealing surface has good sealing effect and anti-torque buckling ability, which can avoid damaging the thread, improve the anti-galling ability of the thread and the tensile and bending resistance of the joint.

[0019] The joint can reduce the interference of the thread, relieve the concentrated stress of the thread, and improve the connection strength and the ability to resist stress corrosion cracking. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of the utility model.

[0021] Figure 2 for Figure 1 A local enlarged view of the S in the middle.

[0022] Figure 3 Schematic diagram of external thread tooth profile.

[0023] Figure 4 Schematic diagram of internal thread tooth profile.

[0024] Figure 5 It is the thread profile diagram in the present utility model. DETAILED DESCRIPTION

[0025] The utility model is further described in detail below in conjunction with the accompanying drawings.

[0026] like Figure 1 , Figure 2 As shown, a sealed threaded joint comprises a coupling 8 and a pipe body 7 engaged therewith, wherein the coupling is provided with an internal thread 1, an internal sealing surface 2 and an internal shoulder surface 3;

[0027] The tube body 7 is provided with an external thread 4, an external sealing surface 5 and an external shoulder surface 6; there is a gap between the external thread 4 and the internal thread 1, and the internal thread 1 and the external thread 4, the internal sealing structure 2 and the external sealing surface 5 form an interference fit to form a main seal;

[0028] The inner shoulder surface 3 cooperates with the outer shoulder surface 6 to form an auxiliary seal; the pipe body 7 is connected to the coupling 8 through a thread, the end of the pipe body is provided with an outer thread 4, the coupling 8 is provided with an inner thread 1, and the thread taper 12 is 1:16. The outer sealing surface 5 of the pipe body is set as an arc surface structure, and a sealing arc surface is set at the inner sealing surface 2 of the coupling to form a sealing surface with the outer sealing surface 5 of the pipe body.

[0029] The pipe body is provided with a reverse end face with a reverse angle, and the angle A between the end face angle and the normal line is 15°. The coupling 8 is provided with a shoulder surface, and the reverse end face and the shoulder surface cooperate to form a secondary sealing surface. The threaded joint for the oil pipe adopts an improved partial trapezoidal thread, and the threaded joint connection for the casing adopts an industrial standard partial trapezoidal thread, and the thread surface is filled with thread grease.

[0030] like Figure 3 As shown, the tooth height (h1) of the external thread 4 is 1.6-1.7 mm, and the tooth width (b1) of the external thread 4 is 1.57.

[0031] like Figure 4 As shown, the internal thread 2 tooth height (h2) is 1.7~1.9mm, and the internal thread 2 tooth width (b2) is 1.55.

[0032] like Figure 5As shown, the guide face angle 9 of the internal and external threads is 15°, the load face angle 10 is -5.5°, the pitch 11 is 6 teeth per inch, and the thread taper 12 is 1:16.

[0033] The working principle of the utility model is as follows:

[0034] The threaded joint comprises a pipe body 7 and a coupling 8, wherein the pipe body is composed of a tapered external thread 4, an external sealing surface 5, and an external shoulder surface 6 at the vertex of the external sealing surface. The coupling 8 is composed of a tapered internal thread 1, an internal sealing surface 2, and a shoulder 3 behind the internal sealing surface.

[0035] The pipe body 7 and the coupling 8 are screwed together by threads. The end of the pipe body has a sealing surface and a shoulder. During the screwing process of the pipe body and the coupling, they come into contact and produce a certain amount of interference. A section of arc surface structure is provided in front of the external thread 4 of the joint and at the external sealing structure 5. The curvature radius of the arc surface is 20mm. The inner sealing surface 2 of the coupling is provided with an inner sealing arc surface, which is interference-fitted with the arc surface structure at the external sealing structure to form a main sealing surface. The pipe body is provided with a concave reverse end face with a reverse angle. The coupling 8 is provided with a shoulder surface. The reverse end face and the shoulder surface are interference-fitted to form a secondary sealing surface. The angle A between the end face angle and the normal is approximately 15°.

[0036] The threaded joints used for oil pipes adopt improved trapezoidal threads, and the threaded joints used for casings adopt industrial standard trapezoidal threads, and the thread surface is filled with thread grease.

[0037] Preferably, the tooth height (h2) of the internal thread 1 is 1.7-1.9 mm, the tooth width (b2) of the internal thread 1 is 1.55, the tooth height (h1) of the external thread 4 is 1.6-1.7 mm, the tooth width (b1) of the external thread 4 is 1.57, and the gap size is 0.15-0.25 mm. The guide surface angle 9 of the internal and external threads is 15°, the load surface angle 10 is -5.5°, the pitch 11 is 6 teeth per inch, the thread taper 12 is 1:16, and the torque shoulder angle A is -15°, which ensures the upper positioning and plays the role of auxiliary sealing.

[0038] The special threaded joint of the utility model has good anti-slip ability. Due to the structure of the arc-shaped sealing surface, the joint has good tensile resistance, compression resistance and bending resistance. At the same time, the design of the reverse shoulder has good sealing effect and anti-over-torque buckling ability, which can avoid damage to the thread.

Claims

1. A sealed threaded joint, characterized in that: It comprises a coupling (8) and a pipe body (7) engaged with the coupling; The upper surface of the tube body (7) is provided with an external thread (4), an external sealing surface (5), and an external shoulder surface (6) in sequence from the middle to the end; The lower surface of the coupling (8) is provided with an internal thread (1), an internal sealing surface (2), and an internal shoulder surface (3) in sequence from the end to the middle; The external thread (4) matches with the internal thread (1), the external sealing surface (5) matches with the internal sealing surface (2), and the external shoulder surface (6) matches with the internal shoulder surface (3); The outer sealing surface (5) is provided with a section of arc surface structure; the inner sealing surface (2) is provided with a section of inner sealing arc surface, and the inner sealing surface (2) and the outer sealing surface (5) are interference-fitted to form a main sealing surface.

2. A sealed threaded joint according to claim 1, characterized in that: The end of the pipe body (7) is provided with an external thread (4), and both ends of the coupling (8) are provided with an internal thread (1), and the thread taper (12) of the pipe body (7) and the coupling (8) as a whole is 1:

16.

3. A sealed threaded joint according to claim 1, characterized in that: The tube body (7) is provided with an inwardly concave reverse end face (A) with a reverse angle of 15°, and the coupling (8) is provided with a shoulder face, and the reverse end face (A) and the shoulder face cooperate to form a secondary sealing face.

4. A sealed threaded joint according to claim 1, characterized in that: The tooth height h2 of the internal thread (1) is 1.7-1.9 mm, the tooth height h1 of the external thread (4) is 1.6-1.7 mm, and the gap size is 0.15-0.25 mm.

5. A sealed threaded joint according to claim 1, characterized in that: The internal thread (1) and the external thread (4) include a guide face angle (9), a load face angle (10) and a pitch (11), wherein the guide face angle (9) is 15°, the load face angle (10) is -5.5°, and the pitch (11) is 6 threads per inch.

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