Coupling-free oil pipe screwed joint
By designing a sealing mating inclined surface, a limiting boss, and a sealing buffer ring structure in the couplingless oil pipe threaded joint, the problem of loosening and separation of the couplingless oil pipe threaded joint under vibration environment is solved, achieving reliable sealing and improved vibration resistance performance, and ensuring the stability and safety of the connection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- JIANGSU CHANGBAO STEELTUBE CO LTD
- Filing Date
- 2025-06-30
- Publication Date
- 2026-05-19
AI Technical Summary
Uncoupling threaded tubing joints are prone to loosening or detachment under vibration, affecting the normal production of oil and gas wells and posing safety risks. Furthermore, on-site installation relies on high-torque tightening operations.
A couplingless oil pipe threaded joint was designed, including a male thread and a female thread. The male and female threads are provided with a sealing mating inclined surface, a limiting boss, an outer annular groove and a shoulder groove, and are equipped with a sealing buffer ring to form a metal sealing and elastic buffer structure, providing radial limiting and axial preload, and enhancing vibration resistance.
It achieves reliable sealing and connection stability in vibration environments, reduces the impact of vibration on the connection, prevents loosening, and ensures long-term stability and safety.
Smart Images
Figure CN224260277U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to a couplingless oil pipe threaded joint, belonging to the technical field of oil casing threaded connection. Background Technology
[0002] In oil and gas extraction operations, the reliability of downhole connections (such as tubing and casing) is crucial. Among these, couplingless tubing, due to its advantages such as a continuous, smooth outer diameter and reduced flow resistance, is widely used in many operating conditions. The tubing is connected via threaded joints. However, in many practical scenarios, especially when there are vibration sources in the well, such as electric submersible pumps, these devices generate continuous mechanical vibrations during operation. This vibrational environment poses a severe challenge to the long-term tightness of the threaded joints in couplingless tubing, easily leading to gradual loosening (loosening) or even complete disconnection (disengagement). Such failures not only affect the normal production of oil and gas wells but, in severe cases, can also lead to major safety accidents such as tubing falling into the well, causing huge economic losses and safety risks.
[0003] Meanwhile, when installing these couplingless oil pipes on site, the tightening (threading) of their threaded joints often relies on the use of pipe wrenches, and the threaded joints often require a high threading torque.
[0004] After searching the existing technology, it was found that Chinese patent CN211549600U discloses an acid-resistant, easy-to-drill, coupling-free aluminum alloy oil pipe. The patent uses a structure with a metal seal and a sealing ring, which has good sealing performance. However, it was found that in the process of use, there is a lack of a suitable limiting structure in the axial direction. Under vibration environment, loosening or disengagement is prone to occur, resulting in connection failure. Summary of the Invention
[0005] The technical problem to be solved by this utility model is to overcome the defects of the prior art and provide a couplingless oil pipe threaded joint that can provide a reliable seal and has good vibration resistance.
[0006] To solve the above-mentioned technical problems, the technical solution of this utility model is: a couplingless oil pipe threaded joint, comprising:
[0007] The male thread is located on one end of the oil pipe. The male thread is provided with an inner shoulder, a sealing mating inclined surface, an external thread, an outer annular groove, a limiting boss and a shoulder groove in sequence from the outside to the inside along the axial direction.
[0008] The female thread is located on the other end of the oil pipe. The female thread is provided with a shoulder end face, a limiting engagement boss, an annular groove, an internal thread, a sealing protrusion, and an inner shoulder groove in sequence from the outside to the inside along the axial direction.
[0009] A sealing buffer ring, wherein the sealing buffer ring is disposed within the outer annular groove of the male thread;
[0010] When the male and female threads are fully engaged, the inner diameter of the male thread is the same as the inner diameter of the oil pipe, and the outer diameter of the female thread is the same as the outer diameter of the oil pipe. The sealing mating inclined surface of the male thread and the sealing protrusion of the female thread fit together to form a first metal sealing surface. The sealing buffer ring is located in the sealing buffer ring receiving space formed by the outer annular groove of the male thread and the annular groove of the female thread. The limiting boss of the male thread abuts against the limiting mating boss of the female thread. The shoulder groove of the male thread and the shoulder end face of the female thread are axially interference fit.
[0011] Furthermore, the pitch of the male external thread and the female internal thread are both 6 threads per inch, and the thread height is 1.32 mm.
[0012] Furthermore, both the external thread of the male thread and the internal thread of the female thread are ACME type cylindrical straight threads.
[0013] Furthermore, when the male thread and the female thread are fully engaged, the radial clearance between the external thread of the male thread and the internal thread of the female thread is 0.2 mm.
[0014] Furthermore, the wall thickness t1 of the shoulder end face of the female buckle is 1.78 mm.
[0015] Furthermore, the axial gap between the inner shoulder of the male buckle and the inner shoulder groove of the female buckle is 0.25mm.
[0016] Furthermore, the external thread of the male thread and the internal thread of the female thread are filled with grease.
[0017] Furthermore, the outer diameter of the oil pipe corresponding to the male and female threads is 73.02 mm.
[0018] By adopting the above technical solution, this utility model has the following beneficial effects:
[0019] In this invention, when the male and female buckles are screwed together, the sealing mating inclined surface of the male buckle abuts against the sealing protrusion of the female buckle, forming a first metal sealing surface, providing radial limiting and rigid sealing. Simultaneously, the sealing buffer ring disposed within the outer annular groove of the male buckle is compressed between itself and the annular groove of the female buckle, forming an elastic buffer sealing structure. This not only improves sealing reliability but also absorbs and buffers vibration to a certain extent, reducing the impact of vibration on connection stability. The limiting boss of the male buckle abuts against the limiting mating boss of the female buckle, providing axial limiting. Furthermore, the shoulder groove of the male buckle and the shoulder end face of the female buckle achieve an interference fit in the axial direction, generating axial preload and improving torsional resistance.
[0020] Secondly, when the male and female threads are fully engaged, the radial clearance between the external thread of the male thread and the internal thread of the female thread is 0.2mm, ensuring smooth thread engagement and providing space for grease. The axial clearance between the inner shoulder of the male thread and the inner shoulder groove of the female thread is 0.25mm, which allows the inner shoulder of the male thread to share the torque when the torque is too high and the shoulder end face of the female thread deforms, which is beneficial for the oil pipe threading operation. The radial width of the shoulder end face of the female thread is 1.78mm, which improves the threading performance and helps prevent loosening.
[0021] In summary, this invention not only achieves reliable sealing but also improves vibration resistance and anti-loosening performance, ensuring the long-term stability and safety of the connection under vibration conditions, and has significant practical value. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of the structure of the couplingless oil pipe threaded joint of this utility model;
[0023] Figure 2 for Figure 1 A magnified view of part A in the middle;
[0024] Figure 3 for Figure 1 A magnified view of part B in the middle section. Detailed Implementation
[0025] To make the contents of this utility model easier to understand, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings.
[0026] like Figure 1-3 As shown, a couplingless oil pipe threaded joint includes:
[0027] Male thread 1 is provided on one end of the oil pipe. Male thread 1 is provided with an inner shoulder 11, a sealing mating inclined surface 12, an external thread 13, an outer annular groove 14, a limiting boss 15, and a shoulder groove 16 in sequence from the outside to the inside along the axial direction.
[0028] The female thread 2 is located on the other end of the oil pipe. The female thread 2 is provided with a shoulder end face 21, a limiting engagement boss, an annular groove, an internal thread, a sealing protrusion 22, and an inner shoulder groove 23 in sequence from the outside to the inside along the axial direction.
[0029] A sealing buffer ring 3 is disposed in the outer annular groove 14 of the male buckle 1;
[0030] When the male buckle 1 and the female buckle 2 are fully engaged, the inner diameter of the male buckle 1 is the same as the inner diameter of the oil pipe, and the outer diameter of the female buckle 2 is the same as the outer diameter of the oil pipe. The sealing mating inclined surface 12 of the male buckle 1 and the sealing protrusion 22 of the female buckle 2 fit together to form the first metal sealing surface. The sealing buffer ring 3 is located in the sealing buffer ring receiving space formed by the outer annular groove 14 of the male buckle 1 and the annular groove of the female buckle 2. The limiting boss 15 of the male buckle 1 abuts against the limiting mating boss of the female buckle 2. The shoulder groove 16 of the male buckle 1 and the shoulder end face 21 of the female buckle 2 are interference fit in the axial direction.
[0031] In this embodiment, as Figure 1-3 As shown, when the male buckle 1 and the female buckle 2 are screwed together, the sealing mating inclined surface 12 of the male buckle 1 abuts against the sealing protrusion 22 of the female buckle 2, forming a first metal sealing surface, providing radial limiting and rigid sealing. Simultaneously, the sealing buffer ring 3, located in the outer annular groove 14 of the male buckle 1, is compressed between itself and the annular groove of the female buckle 2, forming an elastic buffer sealing structure. This not only improves sealing reliability but also absorbs and buffers vibration to a certain extent, reducing the impact of vibration on connection stability. The limiting boss 15 of the male buckle 1 abuts against the limiting mating boss of the female buckle 2, providing limiting and sealing. Furthermore, the shoulder groove 16 of the male buckle 1 and the shoulder end face 21 of the female buckle 2 achieve an interference fit in the axial direction, generating axial preload and improving torsional resistance.
[0032] Specifically, such as Figure 1 As shown, the pitch of the external thread 13 of male thread 1 and the internal thread of female thread 2 are both 6 threads per inch, and the thread height is 1.32 mm.
[0033] Specifically, such as Figure 1 As shown, the external thread 13 of male thread 1 and the internal thread of female thread 2 are both ACME type cylindrical straight threads.
[0034] Specifically, such as Figure 1 As shown, when the male thread 1 and the female thread 2 are fully engaged, the radial clearance between the external thread 13 of the male thread 1 and the internal thread of the female thread 2 is 0.2 mm.
[0035] In this embodiment, as Figure 1-3 As shown, the external thread 13 of male thread 1 and the internal thread of female thread 2 have a tooth profile angle of 27.5°. A radial clearance of 0.2 mm is maintained between the external thread 13 and the internal thread. This clearance provides space for the filling of grease. The grease filling the thread clearance can reduce the frictional resistance during engagement.
[0036] The shoulder end face 21 of the female buckle 2 has a radial width of 1.78 mm, and this shoulder end face 21 forms an interference fit with the shoulder groove 16 of the male buckle 1 in the axial direction. The axial preload generated by the interference fit acts on the shoulder end face 21. An axial clearance of 0.25 mm is provided between the inner shoulder 11 of the male buckle 1 and the inner shoulder groove 23 of the female buckle 2. When the torque causes the shoulder end face 21 to deform, the inner shoulder 11 can abut against the inner shoulder groove 23 to share part of the torque load.
[0037] During the engagement process, the operator first aligns the male thread 1 and the female thread 2, and rotates them to make the external thread 13 engage with the internal thread. As the engagement proceeds, the sealing buffer ring 3 is gradually subjected to radial compression, and the sealing mating inclined surface 12 of the male thread 1 and the sealing protrusion 22 of the female thread 2 gradually come into contact. The limiting boss 15 moves into the limiting mating boss until the shoulder groove 16 and the shoulder end face 21 form an axial interference fit, thus completing the entire connection process.
[0038] Torque tests were conducted on L80 connector oil pipes with a specification of Φ73.02×5.51mm. The yield torques of the two samples were 2710 N·m and 2692 N·m, respectively. The failure location was the fracture at the root of the external thread 13. At the same time, the shoulder end face 21 of the female thread 2 curled up and failed. Taking 50% of the yield torque, i.e., 1300 N·m, as the maximum threading torque.
[0039] Specifically, such as Figure 1 As shown, the wall thickness t1 of the shoulder end face 21 of the female buckle 2 is 1.78 mm.
[0040] Specifically, such as Figure 1 and Figure 3 As shown, the axial clearance between the inner shoulder 11 of the male buckle 1 and the inner shoulder groove 23 of the female buckle 2 is 0.25mm.
[0041] Specifically, such as Figure 1 As shown, the external thread 13 of the male thread 1 and the internal thread of the female thread 2 are filled with grease.
[0042] Specifically, such as Figure 1 As shown, the outer diameter of the oil pipe corresponding to male thread 1 and female thread 2 is 73.02 mm.
[0043] In this embodiment, as Figure 1 and Figure 3 As shown, an axial gap of 0.25mm is provided between the inner shoulder 11 of the male buckle 1 and the inner shoulder groove 23 of the female buckle 2. This gap remains separated under normal engagement. When the external torque exceeds the design load, the shoulder end face 21 of the female buckle 2 will undergo axial deformation. At this time, the inner shoulder 11 enters the inner shoulder groove 23, and the excessive torque load is shared by increasing the contact area, preventing excessive deformation of the shoulder end face 21.
[0044] Grease is filled between the external thread 13 of male thread 1 and the internal thread of female thread 2, with the grease distributed within a radial clearance of 0.2 mm. During thread engagement, the grease reduces direct contact friction between the metal surfaces and simultaneously forms an oil film in the thread clearance, preventing external media from entering the connection. The grease's adhesive properties allow it to remain in the thread clearance for an extended period, providing lubrication for repeated assembly and disassembly.
[0045] The specific embodiments described above further illustrate the technical problems, technical solutions, and beneficial effects of this utility model. It should be understood that the above descriptions are merely specific embodiments of this utility model and are not intended to limit this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.
Claims
1. A premium tubular thread joint, comprising: include: Male thread (1), the male thread (1) is provided on one end of the oil pipe, and the male thread (1) is provided in the following order from the outside to the inside along the axial direction: inner shoulder (11), sealing mating inclined surface (12), external thread (13), outer annular groove (14), limiting boss (15) and shoulder groove (16); The female thread (2) is provided on the other end of the oil pipe. The female thread (2) is provided with a shoulder end face (21), a limiting engagement boss, an annular groove, an internal thread, a sealing protrusion (22), and an inner shoulder groove (23) in sequence from the outside to the inside along the axial direction. A sealing buffer ring (3) is provided in the outer annular groove (14) of the male buckle (1); When the male buckle (1) and the female buckle (2) are fully engaged, the inner diameter of the male buckle (1) is the same as the inner diameter of the oil pipe, and the outer diameter of the female buckle (2) is the same as the outer diameter of the oil pipe. The sealing mating inclined surface (12) of the male buckle (1) and the sealing protrusion (22) of the female buckle (2) fit together to form a first metal sealing surface. The sealing buffer ring (3) is located in the sealing buffer ring receiving space formed by the outer annular groove (14) of the male buckle (1) and the annular groove of the female buckle (2). The limiting boss (15) of the male buckle (1) abuts against the limiting mating boss of the female buckle (2). The shoulder groove (16) of the male buckle (1) and the shoulder end face (21) of the female buckle (2) are axially interference fit.
2. The couplingless oil pipe threaded joint according to claim 1, characterized in that, The external thread (13) of the male thread (1) and the internal thread of the female thread (2) both have a pitch of 6 threads per inch and a thread height of 1.32 mm.
3. The couplingless oil pipe threaded joint according to claim 2, characterized in that, The external thread (13) of the male thread (1) and the internal thread of the female thread (2) are both ACME type cylindrical straight threads.
4. The couplingless oil pipe threaded joint according to claim 1, characterized in that, When the male buckle (1) and the female buckle (2) are fully engaged, the radial gap between the external thread (13) of the male buckle (1) and the internal thread of the female buckle (2) is 0.2 mm.
5. The couplingless oil pipe threaded joint according to claim 1, characterized in that, The wall thickness t1 of the shoulder end face (21) of the female buckle (2) is 1.78 mm.
6. The couplingless oil pipe threaded joint according to claim 1, characterized in that, The axial gap between the inner shoulder (11) of the male buckle (1) and the inner shoulder groove (23) of the female buckle (2) is 0.25 mm.
7. The couplingless oil pipe threaded joint according to claim 1, characterized in that, The external thread (13) of the male thread (1) and the internal thread of the female thread (2) are filled with grease.
8. The couplingless oil pipe threaded joint according to claim 1, characterized in that, The outer diameter of the oil pipe corresponding to the male thread (1) and the female thread (2) is 73.02 mm.