A catheter joint

Abstract

The present application relates to a kind of pipe joints, belong to oil and gas exploitation technical field, including large specification pipe body and respectively being arranged at the outer thread piece and inner thread piece of large specification pipe body two ends, the outer thread piece includes the right angle outer step, transition cylindrical surface, outer thread, metal sealing cone surface and outer thread right angle end face in the direction of outer thread piece from inner thread piece sequentially distributed, the transition cylindrical surface is provided with wedge-shaped sealing groove, the inner thread piece includes the right angle inner shoulder, metal sealing cone hole, inner thread, transition cylindrical hole and inner thread right angle end face in the direction of inner thread piece from outer thread piece sequentially distributed.Thread is directly processed in the two ends of large specification pipe body, the outer diameter of joint is maximally reduced, independent metal / metal seal and elastic seal are designed, and the sealing reliability of joint is high;By increasing thread pitch, optimizing thread tooth type, the screwing performance of thread is greatly improved, and it is convenient for oilfield site operation.

Description

Technical Field

[0001] This invention relates to a conduit connector, belonging to the field of oil and gas extraction technology. Background Technology

[0002] Oilfield conduit pipes are large-diameter pipes, a type of casing, used to secure the walls or boreholes of oil and gas wells. The conduit pipes are inserted into the borehole and secured with cement to help isolate the wellbore from rock formations and prevent wellbore collapse, while also ensuring the circulation of drilling mud to facilitate drilling and extraction.

[0003] Connections between conduits typically employ three methods: snap ring connections, flange bolt connections, and threaded connections. Snap ring connections offer quick installation and disassembly, but poor sealing performance; flange bolt connections utilize mechanical flanges, providing high reliability and good sealing performance, but are time-consuming and inefficient; threaded connections are easy to disassemble and offer good sealing performance, thus becoming the dominant connection method in recent years.

[0004] Chinese invention patent CN201460761U discloses a threaded connector for a water-tight conduit, comprising an internal threaded connector and an external threaded connector fixedly connected to the water-tight conduit. The internal and external threaded connectors are connected by a special oil pipe thread. A sealing element, an O-ring, is provided between the internal and external threaded connectors. This oil pipe thread has 2-4 threads, a taper of 1:12, a lead of 25.4 mm, and a pitch of 6.35 mm. The outer diameter of this connector is much smaller than that of a snap ring connector, meeting production needs. However, this invention lacks a metal seal and therefore lacks gas-tight capability. Furthermore, the outer diameter of the connector is larger than the pipe body, requiring friction welding for connection. This makes it inconvenient for oilfield use.

[0005] Chinese invention patent CN221462262U discloses an anti-backlash surface-mounted conduit threaded connector, comprising a male conduit connector and a female conduit connector. The male conduit connector has a quick-connect male thread on its outer side, and multiple sets of anti-backlash protruding ends are evenly distributed at its bottom end. The female conduit connector has a quick-connect female thread that mates with the quick-connect male thread on its inner side, and a boss at the bottom end of the female conduit connector to limit the screwing depth of the male conduit connector. The top of the boss has several anti-backlash concave surfaces that mate with the multiple sets of anti-backlash protruding ends. This invention incorporates a metal sealing bevel, enhancing sealing reliability. However, while this invention focuses on solving the problems of thread loosening and anti-backlash, issues such as a large outer diameter of the connector and difficulty in threading and mating still exist.

[0006] Therefore, there is a need for a conduit connector that reduces the outer diameter of the connector and improves the sealing reliability and fastening performance of the connector. Summary of the Invention

[0007] The technical problem to be solved by the present invention is: in order to overcome the shortcomings of the prior art, a conduit connector is provided, which minimizes the outer diameter of the connector by means of a coupling-free design, improves the sealing reliability of the connector by simultaneously setting elastic seal and metal / metal seal, and improves the fastening performance of the connector by means of a flat thread guide surface, a large pitch tooth profile and a flat top tooth structure design.

[0008] The technical solution adopted by the present invention to solve the above problems is as follows: a conduit connector, comprising a large-size pipe body and external threaded parts and internal threaded parts respectively disposed at both ends of the large-size pipe body. The external threaded part includes a right-angled external step, a transition cylindrical surface, an external thread, a metal sealing conical surface, and an external thread right-angled end face distributed sequentially from the internal threaded part to the external threaded part. A wedge-shaped sealing groove is provided at the transition cylindrical surface. The internal threaded part includes a right-angled internal shoulder, a metal sealing conical hole, an internal thread, a transition cylindrical hole, and an internal thread right-angled end face distributed sequentially from the external threaded part to the internal threaded part.

[0009] Preferably, an O-ring is placed in the wedge-shaped sealing groove, and after the external threaded part and the internal threaded part are screwed together, the O-ring is pressed through the transition cylindrical hole to achieve sealing. The metal sealing conical surface and the metal sealing conical hole form a radial interference fit, constituting a metal / metal sealing structure.

[0010] Preferably, after the external threaded part and the internal threaded part are screwed together, the external thread and the internal thread form a radial interference fit with an interference amount of 0.02mm to 0.08mm.

[0011] Preferably, the interference fit between the metal sealing conical surface and the metal sealing conical hole is 0.4 mm to 1.0 mm, and the taper of both the metal sealing conical surface and the metal sealing conical hole is 1:6 to 1:8.

[0012] Preferably, when the external threaded part and the internal threaded part are normally screwed together, there is a gap δ1 between the right-angle end face of the external thread and the right-angle inner shoulder, and the gap δ1 is 0.02mm to 0.06mm. When the screwing torque of the external thread and internal thread is too large, when the main shoulder formed by the right-angled outer step and the right-angled end face of the internal thread undergoes plastic deformation, the gap δ1 disappears, and the right-angled end face of the external thread contacts the right-angled inner shoulder to share part of the screwing torque.

[0013] Preferably, both the external and internal threads are tapered pipe threads, and the taper of both the external and internal threads is 1:10.

[0014] Preferably, the external thread includes a first tooth root, a first guide surface, a first tooth tip, and a first bearing surface that are sequentially distributed along the axial direction of the large-size pipe body, wherein the first tooth root and the first tooth tip are both parallel to the axial direction of the large-size pipe body. Both the first guide surface and the first bearing surface are inclined surfaces, and the inclination directions of the first guide surface and the first bearing surface are the same; The tilt angle α1 of the first guide surface is 45° to 55°, and the tilt angle β1 of the first bearing surface is 10° to 15°.

[0015] Preferably, the internal thread includes a second tooth tip, a second guide surface, a second tooth root, and a second bearing surface that are sequentially distributed along the axial direction of the large-size pipe body, wherein the second tooth root and the second tooth tip are both parallel to the axial direction of the large-size pipe body. Both the second guide surface and the second bearing surface are inclined surfaces, and the inclination angle α2 of the second guide surface and the inclination angle β2 of the second bearing surface are the same as α1 and β1, respectively.

[0016] Preferably, the pitch of both the external and internal threads is L, which is 8.467 mm. The tooth width Lp of the external thread is 4.339 mm, the tooth width Lb of the internal thread is 4.234 mm, the tooth height Hp of the external thread is 2.15 mm, and the tooth height Hb of the internal thread is 2.27 mm.

[0017] Preferably, after the internal thread and the external thread engage, there is a gap δ2 between the first tooth tip of the external thread and the second tooth root of the internal thread, the gap δ2 being 0.12 mm, and there is a gap δ3 between the first guide surface of the external thread and the second guide surface of the internal thread, the gap δ3 being 0.105 mm.

[0018] Compared with the prior art, the advantages of the present invention are as follows: 1. Threads are directly machined at both ends of large-diameter pipes, minimizing the outer diameter of the joint; 2. Independent metal / metal seals and elastic seals are designed, ensuring high reliability of the joint seal; 3. By increasing the thread pitch and optimizing the thread tooth profile, the thread engagement performance is greatly improved, making it easier for oilfield operations. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a catheter connector according to the present invention; Figure 2 This is a schematic diagram of the structure of the two connectors before they are screwed together. Figure 3 This is a schematic diagram of the structure after the two parts are twisted together; Figure 4 This is a schematic diagram of a metal / metal sealing structure; Figure 5 This is a schematic diagram of the external thread tooth profile; Figure 6 A schematic diagram of the internal thread tooth profile; Figure 7This is a diagram showing the meshing of internal and external threads.

[0020] Among them: 1. Large-size pipe body; 2. Externally threaded component; 3. Internally threaded component; 4. Shaft; Right-angled external step 21, transition cylindrical surface 22, external thread 23, metal sealing conical surface 24, right-angled end face of external thread 25, wedge-shaped sealing groove 26, O-ring 27; First tooth root 231, first guide surface 232, first tooth tip 233, first bearing surface 234; Right-angle inner shoulder 31, metal sealing tapered hole 32, internal thread 33, transition cylindrical hole 34, internal thread right-angle end face 35; Second tooth tip 331, second guide surface 332, second tooth root 333, second bearing surface 334. Detailed Implementation

[0021] like Figure 1 As shown, a conduit connector in this embodiment includes a large-size pipe body 1 and external threaded parts 2 and internal threaded parts 3 respectively disposed at both ends of the large-size pipe body 1. Here, the large-size pipe body 1 refers to a steel pipe with an outer diameter greater than or equal to 660.4 mm. During use, two of the connectors are assembled. During assembly, the external threaded part 2 of one connector is screwed into the internal threaded part 3 of the other connector, and no coupling is required. like Figure 2 As shown, the external threaded component 2 includes a right-angled external step 21, a transition cylindrical surface 22, an external thread 22, a metal sealing cone surface 24, and an external thread right-angled end face 25, which are distributed sequentially from the internal threaded component 3 to the external threaded component 2. A wedge-shaped sealing groove 26 is provided in the middle of the transition cylindrical surface 22. The internal threaded component 3 includes a right-angled inner shoulder 31, a metal sealing tapered hole 32, an internal thread 33, a transition cylindrical hole 34, and an internal thread right-angled end face 35, which are distributed sequentially from the external threaded component 2 to the internal threaded component 3. like Figure 3 As shown, during the assembly of the two connectors, the external thread 2 and the internal thread 3 on the internal thread 3 are screwed together in an arc shape, and the external thread 22 and the internal thread 33 form a radial interference fit with an interference amount of 0.02mm to 0.08mm. Before screwing in, place an O-ring 27 in the wedge-shaped sealing groove 26; After screwing, the right-angled outer step 21 and the right-angled end face 35 of the internal thread form an axial interference fit, which plays the role of upper locking and positioning and bears the main torque; The transition cylindrical hole 34 presses the O-ring 27 in the wedge-shaped sealing groove 26 to form a radial interference fit, blocking the entry of external fluid and playing a sealing role. The sealing groove is designed as a wedge, which can effectively fix the O-ring 27 and prevent the O-ring 27 from slipping out. like Figure 4 As shown, the metal sealing conical surface 24 and the metal sealing conical hole 32 form a radial interference fit, constituting a metal / metal sealing structure, which can play a gas-tight role. The radial interference between the metal sealing conical surface 24 and the metal sealing conical hole 32 is linearly distributed along the axial direction. Specifically, the interference between the metal sealing conical surface 24 and the metal sealing conical hole 32 is 0.4mm to 1.0mm. The formula for the radial interference between the metal sealing conical surface 24 and the metal sealing conical hole 32 is as follows:

[0022] The radial interference between the metal sealing conical surface 24 and the metal sealing conical hole 32; This is the axial distance starting from the small end of the metal sealing cone surface 24. ; This is the interference fit at the small end, ranging from 0.2 mm to 0.5 mm. This is the interference fit at the large end, ranging from 0.6 mm to 1.2 mm. The axial length of the sealing cone surface. ; Traditional constant interference results in contact pressure concentrated in a certain area of ​​the metal seal cone 24 (such as the small end or the large end), which can easily lead to local yielding or leakage. However, this formula adjusts the distribution of interference along the axial direction to make the sealing contact pressure as equal as possible, avoiding local peaks or valleys, and significantly improving the sealing reliability. Moreover, the interference can be adjusted according to the local radial stiffness, with a smaller interference in areas of weak radial stiffness and a larger interference in areas of strong radial stiffness, to achieve deformation coordination. Secondly, the small end has a small interference (e.g., 0.2 mm), which makes initial alignment easy and prevents damage to the threads and sealing surface. The large end has a large interference (e.g., 1.0 mm), which forms a high-strength metal seal when finally tightened. This inlet-friendly and end-locking mode is particularly suitable for large-diameter conduits, making field operations smoother. The formula makes the sealing contact pressure more uniform along the conical surface, avoiding local overload or leakage; The taper of both the metal sealing conical surface 24 and the metal sealing conical hole 32 is 1:6 to 1:8; The formula for calculating the taper of the metal sealing conical surface 24 and the metal sealing conical hole 32 is as follows:

[0023] C represents the taper value between the metal sealing conical surface 24 and the metal sealing conical hole 32; D is the diameter of the large end of the cone, d is the diameter of the small end of the cone, and L is the length of the cone. It should be noted that under normal screwing conditions, there is a gap δ1 between the right-angle end face 25 of the external thread and the right-angle inner shoulder 31. The gap δ1 is 0.02mm to 0.06mm. When the torque is too large, the main shoulder formed by the right-angle outer step 21 and the right-angle end face 35 of the internal thread undergoes plastic deformation, the gap δ1 disappears, and the right-angle end face 25 of the external thread and the right-angle inner shoulder 31 come into contact and share part of the screwing torque. Both the external thread 22 and the internal thread 33 are tapered pipe threads, and the taper of both the external thread 22 and the internal thread 33 is 1:10. like Figure 5 As shown, the external thread 22 includes a first tooth root 231, a first guide surface 232, a first tooth tip 233 and a first bearing surface 234 distributed sequentially along the axis 4 of the large-size pipe body 1. The first tooth root 231 and the first tooth tip 233 are both parallel to the axis 4 of the large-size pipe body 1. Compared with the prior art which is parallel to the thread generatrix, the design of parallel axis 4 makes it less likely to be mis-threaded when going down into the well in the oil field, which is convenient for on-site operation in the oil field. Both the first guide surface 232 and the first bearing surface 234 are inclined surfaces, and the inclination directions of the first guide surface 232 and the first bearing surface 234 are the same. In this way, the thread is sawtooth-shaped, which can improve its connection efficiency. The inclination angle α1 of the first guide surface 232 is 45° to 55°, and the inclination angle β1 of the first bearing surface 234 is 10° to 15°. The gentle angle α1 makes the joint easy to engage. It should be noted that angle α1 is the angle between the first guide surface 232 and the perpendicular line of the thread axis, and angle β1 is the angle between the first bearing surface 234 and the perpendicular line of the thread axis. The inclination angle α1 of the first guide surface 232 and the angle β1 between the first bearing surface 234 and the perpendicular line to the thread axis satisfy the following relationship to ensure over-torque resistance:

[0024] like Figure 6 As shown, the internal thread 33 includes a second tooth tip 331, a second guide surface 332, a second tooth root 333, and a second bearing surface 334, which are distributed sequentially along the axis 4 of the large-size pipe body 1. The second tooth root 333 and the second tooth tip 331 are both parallel to the axis 4 of the large-size pipe body 1. The second guide surface 332 and the second bearing surface 334 are both inclined surfaces, and the inclination angle α2 of the second guide surface 332 and the inclination angle β2 of the second bearing surface 334 are the same as α1 and β1, respectively. The pitch of both the external thread 22 and the internal thread 33 is L, which is 8.467 mm. The tooth width Lp of the external thread 22 is 4.339 mm, the tooth width Lb of the internal thread 33 is 4.234 mm, the tooth height Hp of the external thread 22 is 2.15 mm, and the tooth height Hb of the internal thread 33 is 2.27 mm. like Figure 7 As shown, since the tooth width Lp of the external thread 22 is greater than the tooth width Lb of the internal thread 33, and the tooth height Hb of the internal thread 33 is greater than the tooth height Hp of the external thread 22, after the internal thread 33 meshes with the external thread 22, there is a gap δ2 between the first tooth tip 233 of the external thread 22 and the second tooth root 333 of the internal thread 33, and the gap δ2 is 0.12mm. There is also a gap δ3 between the first guide surface 232 of the external thread 22 and the second guide surface 332 of the internal thread 33, and the gap δ3 is 0.105mm. Gap δ2 and gap δ3 are used to store thread grease, maintain good lubrication of the thread surface, facilitate joint engagement, and prevent thread sticking. In summary, the direct machining of threads on both ends of the large-size pipe body 1 minimizes the outer diameter of the joint. Independent metal / metal seals and elastic seals are designed. After the joint is screwed on, the outer shoulder 21 contacts first, bearing the torque. As the torque increases, the inner shoulder 31 begins to contact, sharing some of the torque. This design eliminates the need for couplings; the threads are directly machined onto the large-size pipe body 1, and the outer diameter of the joint is flush with the large-size pipe body 1, making well entry easier. Simultaneously, the joint has high sealing reliability, strong torsional resistance, and is less prone to sticking. By increasing the thread pitch and optimizing the thread tooth profile, the threading performance is greatly improved, facilitating field operations in the oilfield.

[0025] In addition to the above embodiments, the present invention also includes other embodiments. All technical solutions formed by equivalent transformation or equivalent substitution should fall within the protection scope of the claims of the present invention.

Claims

1. A pipe joint comprising a large-diameter pipe body (1) and an external thread member (2) and an internal thread member (3) provided at both ends of the large-diameter pipe body (1), respectively, characterized in that The external threaded component (2) includes a right-angled outer step (21), a transition cylindrical surface (22), an external thread (22), a metal sealing cone surface (24), and an external thread right-angled end face (25) distributed sequentially from the internal threaded component (3) to the external threaded component (2). A wedge-shaped sealing groove (26) is provided at the transition cylindrical surface (22). The internal threaded component (3) includes a right-angled inner shoulder (31), a metal sealing cone hole (32), an internal thread (33), a transition cylindrical hole (34), and an internal thread right-angled end face (35) distributed sequentially from the external threaded component (2) to the internal threaded component (3). After the external threaded part (2) and the internal threaded part (3) are screwed together, the metal sealing cone surface (24) and the metal sealing cone hole (32) form a radial interference fit, forming a metal / metal sealing structure. The radial interference between the metal sealing cone surface (24) and the metal sealing cone hole (32) is linearly distributed along the axial direction. The formula for the radial interference between the metal sealing conical surface (24) and the metal sealing conical hole (32) is: ； The radial interference between the metal sealing conical surface (24) and the metal sealing conical hole (32); The axial distance starting from the small end of the metal sealing cone surface (24) is the distance from the small end of the cone surface. ; This is the interference fit at the small end, ranging from 0.2 mm to 0.5 mm. This is the interference fit at the large end, ranging from 0.6 mm to 1.2 mm. The axial length of the sealing cone surface. .

2. The catheter connector according to claim 1, characterized in that... An O-ring (27) is placed in the wedge-shaped sealing groove (26). After the external threaded part (2) and the internal threaded part (3) are screwed together, the O-ring (27) is pressed through the transition cylindrical hole (34) to achieve sealing.

3. The catheter connector according to claim 1, characterized in that... After the external threaded part (2) and the internal threaded part (3) are screwed together, the interference is 0.02mm to 0.08mm.

4. The catheter connector according to claim 3, characterized in that... The interference fit between the metal sealing conical surface (24) and the metal sealing conical hole (32) is 0.4 mm to 1.0 mm.

5. The catheter connector according to claim 1, characterized in that... The taper of the metal sealing conical surface (24) and the metal sealing conical hole (32) is 1:6 to 1:8; The formula for calculating the taper of the metal sealing conical surface (24) and the metal sealing conical hole (32) is as follows: ； C represents the taper value between the metal sealing conical surface (24) and the metal sealing conical hole (32); D is the diameter of the large end of the cone, d is the diameter of the small end of the cone, and L is the length of the cone.

6. The catheter connector according to claim 1, characterized in that... When the external threaded part (2) and the internal threaded part (3) are normally screwed together, there is a gap δ1 between the right-angle end face (25) of the external thread and the right-angle inner shoulder (31), and the gap δ1 is 0.02mm to 0.06mm. When the screwing torque of the external threaded part (2) and the internal threaded part (3) is too large, when the main shoulder formed by the right-angled outer step (21) and the right-angled end face (35) of the internal thread undergoes plastic deformation, the gap δ1 disappears, and the right-angled end face (25) of the external thread contacts the right-angled inner shoulder (31) to share part of the screwing torque.

7. The catheter connector according to claim 1, characterized in that... The external thread (22) and internal thread (33) are both tapered pipe threads, and the taper of the external thread (22) and internal thread (33) is 1:

10.

8. The catheter connector according to any one of claims 1-7, characterized in that... The external thread (22) includes a first tooth root (231), a first guide surface (232), a first tooth tip (233) and a first bearing surface (234) distributed sequentially along the axis (4) of the large-size pipe body (1). The first tooth root (231) and the first tooth tip (233) are both parallel to the axis (4) of the large-size pipe body (1). Both the first guide surface (232) and the first bearing surface (234) are inclined surfaces, and the inclination directions of the first guide surface (232) and the first bearing surface (234) are the same; The inclination angle α1 of the first guide surface (232) and the angle β1 between the first bearing surface (234) and the perpendicular line to the thread axis satisfy the following relationship: ； The tilt angle α1 of the first guide surface (232) is 45° to 55°, and the tilt angle β1 of the first bearing surface (234) is 10° to 15°.

9. The catheter connector according to claim 8, characterized in that... The internal thread (33) includes a second tooth tip (331), a second guide surface (332), a second tooth root (333), and a second bearing surface (334) distributed sequentially along the axis (4) of the large-size pipe body (1). The second tooth root (333) and the second tooth tip (331) are both parallel to the axis (4) of the large-size pipe body (1). The second guide surface (332) and the second bearing surface (334) are both inclined surfaces. The inclination angle α2 of the second guide surface (332) and the inclination angle β2 of the second bearing surface (334) are consistent with α1 and β1, respectively.

10. The catheter connector according to claim 8, characterized in that... The pitch of both the external thread (22) and the internal thread (33) is L, the pitch L is 8.467mm, the tooth width Lp of the external thread (22) is 4.339mm, the tooth width Lb of the internal thread (33) is 4.234mm, the tooth height Hp of the external thread (22) is 2.15mm, and the tooth height Hb of the internal thread (33) is 2.27mm. After the internal thread (33) and the external thread (22) are engaged, there is a gap δ2 between the first tooth tip (233) of the external thread (22) and the second tooth root (333) of the internal thread (33), the gap δ2 is 0.12mm. There is a gap δ3 between the first guide surface (232) of the external thread (22) and the second guide surface (332) of the internal thread (33), the gap δ3 is 0.105mm.

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