Connection device for tubular elements

Abstract

The invention relates to a connection device (1) comprising a first tubular element (3), a second tubular element (2), and a coupling sleeve (4) for connecting the first tubular element (3) to the second tubular element (2); a first male portion (6) of the first tubular element (3) comprises a free end with an annular sealing lip (16) configured to cover an outer sealing surface (14) of the second tubular element (2), the sealing lip (16) having an outer periphery (17) on which an outer threaded portion (12) is formed.

Description

Technical Field

[0001] This invention relates to a connection device for providing a sealed connection between two tubular elements. The invention particularly relates to a connection device designed for use in gas or oil wells to form drill pipe, casing, or production strings. Background Technology

[0002] Connection devices designed for use in gas or oil wells are known in the prior art. These devices include a first tubular element, a second tubular element, and a connecting sleeve for sealingly connecting the first and second tubular elements together. Each tubular element has a threaded convex portion that is screwed into a threaded concave portion of the connecting sleeve.

[0003] This type of connecting device is known, in which the connecting sleeve has an inwardly projecting flange. Such a connecting device is described, for example, in document FR3027649. The flange has two axially stopping surfaces designed to mate with corresponding axially stopping surfaces located at the free ends of the first and second tubular elements. The sleeve also has two sealing surfaces that mate with corresponding sealing surfaces of the first and second tubular elements. This connecting device is not entirely satisfactory, particularly because the flange and the two sealing surfaces complicate the connecting sleeve and increase manufacturing costs.

[0004] Document US2012 / 0074692 addresses this problem by proposing a connecting device in which a stop and seal function is performed between the two free ends of two tubular elements screwed into a connecting sleeve. For this purpose, the free ends of the first and second tubular elements have axial stop surfaces. Furthermore, the free end of one of the tubular elements has an annular sealing lip that interferes with a truncated conical sealing surface disposed on the outer surface of the other tubular element to seal the connection when the axial stop surfaces contact each other. However, such a connecting device is not entirely satisfactory. In practice, the axial stop surfaces must be large enough to withstand the significant tightening torque applied when one of the tubular elements is screwed into the connecting sleeve until the axial stop surface contacts the axial stop surface of the other tubular element. Therefore, the annular sealing lip must be made with a small amount of material, making it particularly fragile and compromising the reliability of contact between the sealing lip and the corresponding truncated conical sealing surface. Summary of the Invention

[0005] The core idea of ​​this invention is to propose a connection device of the aforementioned type, which is simpler to manufacture and ensures a reliable seal for the connection.

[0006] According to one embodiment, the present invention provides a connecting device comprising a first tubular element, a second tubular element, and a connecting sleeve for connecting the first tubular element and the second tubular element; the connecting sleeve includes a first concave portion having a first internal thread and a second concave portion having a second internal thread, the first tubular element having a first convex portion, and the second tubular element having a second convex portion, the first convex portion having a first external thread designed to mate with the first internal thread of the connecting sleeve and a second external thread designed to mate with the second internal thread of the connecting sleeve, so as to enable threaded connection from the first convex portion to the first concave portion and threaded connection from the second convex portion to the second concave portion.

[0007] The first convex portion includes a free end having a first axial stop surface, and the second convex portion includes a free end having a second axial stop surface and an outer sealing surface. The outer sealing surface extends between the second axial stop surface and the second external thread portion. The second axial stop surface is designed such that when the first convex portion and the second convex portion are respectively connected to connection positions located inside the first concave portion and inside the second concave portion, the second axial stop surface contacts the first axial stop surface. The free end of the first convex portion also has an annular sealing lip that protrudes axially relative to the first axial stop surface. The sealing lip is designed such that when the first axial stop surface and the second axial stop surface contact each other, the sealing lip covers the outer sealing surface and makes radial sealing contact with the outer sealing surface. The sealing lip has an outer periphery on which a portion of the first external thread portion is formed.

[0008] The connecting device with the above-described features is particularly advantageous because it helps simplify the manufacture of the connecting sleeve due to the seal formed between the first and second tubular elements. Furthermore, because of the first external thread on the sealing lip, a large amount of material is used to form the sealing lip. The large amount of material used to manufacture the sealing lip ensures that it is sufficiently rigid to ensure sealing contact with the external sealing surface and to guarantee the sealing performance of the device.

[0009] According to one embodiment, such a connecting device may have one or more of the following features.

[0010] According to one embodiment, the first external thread portion has a tapered portion and a cylindrical portion, the cylindrical portion being axially positioned between the tapered portion and the free end of the first convex portion, such that the cylindrical portion is at least partially disposed on the sealing lip. These features increase the radial thickness of the sealing lip, thereby increasing the rigidity of the sealing lip and thus increasing the reliability of the device seal.

[0011] According to one embodiment, the first internal thread portion, designed to mate with the cylindrical portion of the first external thread portion, is tapered.

[0012] According to one embodiment, the cylindrical portion of the first external thread and the first tapered internal thread engage in an interference manner, preferably in an axial interference manner, to provide a self-locking effect.

[0013] Therefore, according to one embodiment, the first external thread portion includes a thread portion having an insertion side and a bearing side, the insertion side being oriented toward the free end of the first convex portion, and the bearing side being oriented in the opposite direction. The first external thread portion includes an axial pressure region in the connection position, the axial pressure region extending from the free end of the first convex portion between a first region and a second region. In the first region, axial interference begins between the insertion side and the corresponding surface of the first internal thread portion. Starting from the second region, the insertion side no longer interferes with the corresponding surface of the first internal thread portion, while the bearing side interferes with the corresponding region of the first internal thread portion.

[0014] According to one embodiment, the axial pressure region has between one and four teeth.

[0015] According to one embodiment, the first or second convex portion is a millend (factory-assembled end) and the other portion is a field end. The millend is designed to be connected to the coupling sleeve before the field end.

[0016] According to an advantageous embodiment, the first convex portion is at the factory-assembled end, and the second convex portion is at the field end. Alternatively, the first convex portion is at the field end, and the second convex portion is at the factory-assembled end.

[0017] According to one embodiment, the connecting sleeve has an additional axial stop surface that protrudes radially toward the inside of the connecting sleeve from an intermediate portion located between a first internal thread portion and a second internal thread portion, and a sealing lip is designed such that when the first convex portion is in the connected position, the sealing lip is in axial contact with the additional axial stop surface.

[0018] According to one embodiment, the first tubular element has a visual mark arranged at a predetermined distance from the first axial stop surface. This visual mark ensures that the first tubular element is positioned relative to the connecting sleeve in a predetermined manner.

[0019] According to one embodiment, the end teeth of the first external thread are designed to contact an additional axial stop surface in the engagement position. In other words, the teeth of the first external thread positioned closest to the free end of the sealing lip are designed to mate with the additional axial stop surface. According to one embodiment, the radial height of the additional stop surface is equal to or greater than half the radial height of the end teeth. According to one embodiment, the radial height of the additional stop surface is equal to or less than the radial height of the end teeth.

[0020] According to one embodiment, the second external thread portion is frustoconical and the second internal thread portion is frustoconical.

[0021] According to one embodiment, the coupling sleeve has a threadless intermediate portion disposed between a first internal thread portion and a second internal thread portion. The advantage of this intermediate portion is that it forms an empty space for receiving excess grease.

[0022] According to one embodiment, the axial length of the intermediate portion is equal to or greater than one pitch of the first external thread, and preferably greater than two pitches of the first external thread. This pitch is, for example, the distance between the insertion sides of two consecutive teeth of the first external thread or the distance between the bearing sides of two consecutive teeth. This length of the intermediate portion creates significant free space to accommodate the first external thread.

[0023] According to one embodiment, in the connected position, one end of the intermediate portion is axially positioned between the free end of the sealing lip and the first axial stop surface. Preferably, the axial distance separating the first axial stop surfaces at the end of the intermediate portion is equal to or less than one pitch of the first external thread. These features reduce stress concentrated on the radius at the tip of the stop. Furthermore, these features provide good axial stability for the sealing lip and thus a more reliable seal for the connection.

[0024] According to one embodiment, a recess is formed in the middle portion, and a first external thread portion is partially seated in the recess.

[0025] According to one embodiment, the intermediate portion is positioned such that when the first axial stop surface and the second axial stop surface are in contact with each other, the sealing lip is in radial contact with the outer sealing surface on the radially inner side of the intermediate portion.

[0026] According to one embodiment, when the first axial stop surface and the second axial stop surface are in contact with each other, the radial contact of the seal between the sealing lip and the outer sealing surface is formed with a radial interference measured in millimeters, the radial interference being equal to or greater than twice the radial distance separating the first external thread portion from the intermediate portion of the connecting sleeve. Preferably, this distance between the first external thread portion and the intermediate portion is measured at the end teeth of the first external thread portion.

[0027] According to one embodiment, when the first axial stop surface and the second axial stop surface are in contact with each other, the radial contact of the seal between the sealing lip and the outer sealing surface is formed with radial interference, causing the sealing lip to deform radially outward, thereby making the first external threaded portion contact the middle portion of the connecting sleeve. This contact provides good radial stability for the seat portion of the sealing lip to abut against the middle portion, thereby ensuring a reliable seal.

[0028] According to one embodiment, the first tubular element, the second tubular element, and the connecting sleeve are made of steel.

[0029] According to one embodiment, the first external thread and the first internal thread contact each other with a greater degree of interference in the interference zones compared to the degree of interference between the second external thread and the second internal thread. Preferably, the degree of interference between the first external thread and the first internal thread is more than 10% greater than the degree of interference between the second external thread and the second internal thread. This degree of interference is related, for example, to the depth of interference measured in millimeters or to the measured values ​​of the surface in terms of interference. Therefore, the tightening torque of the first convex portion is greater than the tightening torque of the second convex portion, which prevents the first convex portion from being unscrewed from the connecting sleeve when the second convex portion is tightened. Attached Figure Description

[0030] The invention will be better understood and its additional objects, details, features and advantages will be more clearly set forth in the following detailed description of several specific embodiments of the invention, given by way of non-limiting example only with reference to the accompanying drawings.

[0031] Figure 1 This is a cross-sectional view of a connecting device according to one embodiment.

[0032] Figure 2 yes Figure 1 A detailed cross-sectional view of the connecting device according to the first variant embodiment.

[0033] Figure 3 yes Figure 1 A detailed cross-sectional view of the connecting device according to a second variant embodiment.

[0034] Figure 4 yes Figure 1 A detailed cross-sectional view of the connecting device according to a third variant embodiment. Detailed Implementation

[0035] In the specification and drawings, axis X is the screwing axis of the tubular element of the connecting device. By convention, the "radial" direction is orthogonal to axis X, and the axial direction is parallel to axis X. The terms "external" and "internal" are used to define the relative position of the element with respect to axis X; therefore, elements closer to axis X are considered internal, as opposed to external elements located on the radially outer periphery.

[0036] See below Figure 1 and Figure 2 A connecting device 1 according to a first embodiment is described. The connecting device 1 includes a first tubular element 3, a second tubular element 2, and a connecting sleeve 4 for sealingly connecting the tubular elements 2 and 3 together. The tubular elements 2 and 3 and the connecting sleeve 4 are generally made of steel.

[0037] Each tubular element 2, 3 has two ends. Figure 1 Only one of the two ends is shown, each end having a convex portion 5, 6, which is designed to screw into the corresponding concave portion 7, 8 of the connecting sleeve 4. This allows multiple tubular elements 2, 3 to be sequentially and sealingly connected to each other, for example to form a drill string, casing string, or production string for a gas well or oil well.

[0038] Each convex portion 5, 6 has external threads 11, 12, which are designed to mate with the internal threads 9, 10 of one of the concave portions 7, 8 of the connecting sleeve 4. More specifically, the convex portion 6 of the first tubular element 3 has a first external thread 12, which is designed to mate with the first internal thread 10 of the connecting sleeve 4, and the convex portion 5 of the second tubular element 2 has a second external thread 11, which is designed to mate with the second internal thread 9 of the connecting sleeve 4. Advantageously, the connecting sleeve 4 has an intermediate portion 18 positioned between the first internal thread 10 and the second internal thread 9 to form an empty space designed to receive excess grease. In the example shown, the diameter of the intermediate portion 18 is substantially equal to the root diameter of the first adjacent threads of the first internal thread 9 and the second internal thread 10 of the connecting sleeve 4. According to a variant embodiment, the diameter of the middle portion may also be slightly smaller than the root diameter of the first adjacent thread of the first internal thread portion 10 of the connecting sleeve 4, which helps to further enhance the self-locking effect of the convex portion 6 of the first tubular element 3 in the connecting sleeve 4 (described below).

[0039] In the embodiments described below, the convex portion 6 of the first tubular element 3 is designed to be screwed into the connecting sleeve 4 before the convex portion 5 of the second tubular element 2 is screwed into the connecting sleeve. Thus, for example, the convex portion 6 of the first tubular element 3 can be pre-assembled with the connecting sleeve 4 in the factory, while the convex portion 5 of the second tubular element 2 is assembled with the connecting sleeve 4 at a later time, at the installation site of the gas well or oil well. In this case, the convex portion 6 of the first tubular element 3 is generally referred to as the "mill end," and the convex portion 5 of the second tubular element 2 is referred to as the "field end." To prevent the first tubular element 6 from being unscrewed from the connecting sleeve 4 when the second tubular element 2 is screwed on, the tightening torque of the first tubular element 3 in the connecting sleeve 4 caused by the engagement of the first external thread 12 with the first internal thread 10 of the connecting sleeve 4 is greater than the tightening torque of the second tubular element 2 caused by the engagement of the second external thread 11 with the second internal thread 9 of the connecting sleeve 4. Preferably, the tightening torque of the first tubular element 3 in the connecting sleeve 4 is more than 10% greater than the tightening torque of the second tubular element 2. To ensure this, when in the stop position (also known as the connected position), the threaded portion of the first external thread 12 contacts the threaded portion of the first internal thread 10 in an interference region. The surface area of ​​this interference region is greater than the surface area of ​​the interference region between the threaded portion of the second external thread 11 and the threaded portion of the second internal thread 9, and preferably, the surface area of ​​this interference region is more than 10% greater than the surface area of ​​the interference region between the threaded portion of the second external thread 11 and the threaded portion of the second internal thread 9. Alternatively or additionally, when in the connected position, the threaded portion of the first external thread 12 contacts the threaded portion of the first internal thread 10 with an interference degree measured in millimeters that is greater than the interference degree measured in millimeters between the threaded portions of the second external thread 11 and the threaded portions of the second internal thread 9, and preferably the interference degree between the threaded portions of the first external thread 12 and the threaded portions of the first internal thread 10 is more than 10% greater than the interference degree measured in millimeters between the threaded portions of the second external thread 11 and the threaded portions of the second internal thread 9.

[0040] exist Figure 1 and Figure 2In the illustrated embodiment, the first internal thread portion 10 of the connecting sleeve 4 is truncated tapered, such that the first internal thread portion 10 has an inclination angle relative to the axis X. In other words, the diameter of the thread portion of the first internal thread portion 10 of the connecting sleeve 4 increases from the middle portion 18 of the connecting sleeve 4 toward the end of the connecting sleeve 4 located on the side of the first internal thread portion 10. The first external thread portion 12 of the first tubular element 3 is tapered. In other words, the first external thread portion 12 has a truncated tapered portion in which the diameter of the thread portion decreases toward the free end of the convex portion 6 of the first tubular element 3, and then continues to the cylindrical portion of the first external thread portion, in which the diameter of the thread portion remains constant until the free end of the convex portion 6.

[0041] In an advantageous embodiment, the cylindrical portion of the first external thread 12 is long enough to achieve a self-locking effect, i.e., when the first external thread 12 is engaged with the first internal thread 10, the tightening torque is increased by interference. Therefore, for a predetermined tightening torque, the relative position of the convex portion 6 within the connecting sleeve 4 can be determined according to the torque within manufacturing tolerances. In practice, the convex portion 6 of the first tubular element 3 is screwed into the connecting sleeve 4 until a threshold connecting torque is reached, thereby ensuring the predetermined relative positioning of the first element with respect to the connecting sleeve 4.

[0042] like Figure 2 As shown, each of the threaded portions in the first external threaded portion 11 and the second external threaded portion 12 is formed by a stabbing flank 19 and a loading flank 20. The stabbing flank 19 is arranged upstream of the loading flank 20. In other words, the stabbing flank 19 of the first external threaded portion 12 is oriented toward the free end of the first tubular element 3, while the loading flank 20 is positioned away from the free end.

[0043] like Figure 3As shown in the embodiment, in order to achieve the aforementioned self-locking effect using the truncated conical and cylindrical-conical shapes of the first internal thread portion 10 and the truncated conical and cylindrical-conical shapes of the first external thread portion 12, the first external thread portion 12 has an axial pressure region 21. This axial pressure region 21 extends downstream between a first region 22 and a second region 23. In the first region 22, interference begins between the penetrating side 19 and the corresponding surface of the first internal thread portion 10. In the second region 23, the penetrating side 19 no longer interferes with the corresponding surface of the first internal thread portion 10, while the bearing side 20 interferes with the corresponding region of the first internal thread portion 10. Preferably, the axial pressure region 21 has between one and four teeth, each tooth being a portion of the thread portion extending 360° around the axis X. In other words, the axial pressure region 21 corresponds to the portion of the thread portion of the first external thread portion 12 extending in an angular range between 360° and 1440° around the axis X. This ensures a satisfactory self-locking effect, especially when screwed onto the factory-installed end. Furthermore, this enhances the axial stability of the sealing lip 16 described below.

[0044] According to other embodiments, the first internal thread portion 10 and the first external thread portion 12 may not have the aforementioned structure that provides a self-locking effect. In this case, the first tubular element 3 may be provided with a visual mark positioned at a predetermined distance from the free end of the convex portion 6 of the first tubular element 3, thereby ensuring the predetermined relative positioning of the first tubular element 3 with respect to the connecting sleeve 4.

[0045] Furthermore, the second internal thread portion 9 of the connecting sleeve 4 and the second external thread portion 11 of the second tubular element 2 are truncated tapered. In addition, the diameter of the thread portion of the second internal thread portion 9 of the connecting sleeve 4 increases from one end of the connecting sleeve 4 towards the end of the connecting sleeve 4, while the diameter of the thread portion of the external thread portion 11 of the second tubular element 2 decreases towards the free end of the second tubular element 2.

[0046] like Figure 2 As shown in detail, the free end of the convex portion 6 has a first axial stop surface 15 and an annular sealing lip 16, which protrudes axially from the first axial stop surface 15 and radially to the outside of said surface. The free end of the convex portion 5 of the second tubular element 2 has a second axial stop surface 13 and an outer sealing surface 14 extending between the second axial stop surface 13 and the second external thread portion 11. The outer sealing surface 14 extends obliquely relative to the axis X, such that the diameter of the convex portion 5 decreases from the second external thread portion 11 toward the second axial stop surface 13.

[0047] Therefore, when the convex portion 5 of the second tubular element 2 is screwed into the connecting sleeve 4, the second axial stop surface 13 abuts against the first axial stop surface 15 in the axial direction, which indicates that the second tubular element 2 has reached the desired predetermined position.

[0048] In addition, the sealing lip 16 contacts the outer sealing surface 14, which ensures a seal between the first tubular element 2 and the second tubular element 3.

[0049] More specifically, the sealing lip 16 includes an inner surface having a sealing seat, also referred to as the sealing surface of the sealing lip 16. The inner surface of the sealing lip 16 is machined such that when the second tubular element 2 is screwed into the connecting sleeve 4, the outer sealing surface 14 abuts against the sealing seat of the inner surface of the sealing lip 16, causing the sealing seat of the sealing lip 16 to elastically deform. This interference-type contact ensures a seal between the outer sealing surface 14 and the connecting sleeve 4.

[0050] In the illustrated embodiment, the first axial stop surface 13 and the second axial stop surface 15 have matching frustoconical shapes. More specifically, the first axial stop surface 15 has a frustoconical shape oriented such that the radial portion of the first axial stop surface 15 decreases towards the end of the first convex portion 6, while the second axial stop surface 13 has a frustoconical shape oriented such that the radial portion of the second axial stop surface 13 increases towards the end of the second convex portion 5. According to an advantageous embodiment, the matching frustoconical shapes have a half-angle of less than 90° and advantageously greater than 70° at the apex, for example, a half-angle of about 75° at the apex. When the axial stop surfaces 13, 15 are engaged, these inclinations of the first axial stop surface 13 and the second axial stop surface 15 tend to press the outer sealing surface 14 against the sealing lip 16, thereby ensuring satisfactory sealing contact.

[0051] like Figure 1 and Figure 2 As shown, the sealing lip 16 has an outer peripheral portion 17 on which a portion of a first external thread 12 is formed. This arrangement is particularly advantageous because the outer peripheral portion 17 strengthens the sealing lip 16 by increasing the amount of material used to manufacture the lip 16. Advantageously, due to the cylindrical shape of the first external thread 12 at the end of the first convex portion 6, the amount of material used to manufacture the sealing lip 16 is also greater.

[0052] In an alternative embodiment, the structures of the free ends of the first convex portion 5 and the second convex portion 6 are reversed, such that the sealing lip 16 is disposed on the convex portion 5 and the outer sealing surface 14 is disposed on the convex portion 6.

[0053] Figure 4 Another embodiment is shown, wherein the connecting sleeve 4 has an additional axial stop surface 24 formed in the intermediate portion 18 of the connecting sleeve 4, and the end of the sealing lip 16 is designed such that when the first tubular element 3 is screwed into the connecting sleeve 4, the end of the sealing lip 16 contacts the additional axial stop surface 24. This additional axial stop surface 24 ensures the predetermined relative positioning of the first tubular element 3 with respect to the connecting sleeve 4, even when the first external thread portion 12 and the first internal thread portion 10 do not provide a self-locking effect. In the illustrated embodiment, the additional axial stop surface 24 is formed by the side of an annular flange 25 projecting radially toward the inside of the connecting sleeve 4.

[0054] Although the invention has been described in conjunction with several specific embodiments, it is apparent that the invention is by no means limited thereto, and that the invention includes all technical equivalents and combinations thereof of the described means, wherein such technical equivalents and combinations thereof fall within the scope of the invention.

[0055] The use of the verbs “comprising” or “including” when enumerating does not exclude the presence of other elements or steps besides those mentioned in the claims.

[0056] In the claims, the reference numerals between parentheses should not be construed as constituting a limitation on the claims.

Claims

1. A connecting device (1) comprising a first tubular element (3), a second tubular element (2), and a connecting sleeve (4) for connecting the first tubular element (3) and the second tubular element (2); the connecting sleeve (4) comprising a first concave portion (8) having a first internal thread (10) and a second concave portion (7) having a second internal thread (9), the first tubular element (3) having a first convex portion (6), and the second tubular element (2) having a second convex portion (5), the first convex portion (6) having a first external thread (12) designed to mate with the first internal thread (10) of the connecting sleeve (4), and the second convex portion (5) having a second external thread (11) designed to mate with the second internal thread (9) of the connecting sleeve (4), such that threaded connection from the first convex portion (6) to the first concave portion (8) and threaded connection from the second convex portion (5) to the second concave portion (7) can be achieved. The first convex portion (6) includes a free end having a first axial stop surface (15), and the second convex portion (5) includes a free end having a second axial stop surface (13) and an outer sealing surface (14). The outer sealing surface (14) extends between the second axial stop surface (13) and the second external thread portion (11). The second axial stop surface (13) is designed such that when the first convex portion (6) and the second convex portion (5) are respectively connected in a connection position located inside the first concave portion (8) and the second concave portion (7), the second axial stop surface (13) and the second convex portion (5) are connected. The first convex portion (6) is in contact with an axial stop surface (15), and the free end of the first convex portion (6) also has an annular sealing lip (16) that protrudes axially relative to the first axial stop surface (15). The sealing lip (16) is designed such that when the first axial stop surface (15) and the second axial stop surface (13) are in contact with each other, the sealing lip (16) covers the outer sealing surface (14) and makes radial sealing contact with the outer sealing surface (14). The sealing lip (16) has an outer peripheral portion (17), on which a portion of the first external thread portion (12) is formed. The first external thread portion (12) has a tapered portion and a cylindrical portion, the cylindrical portion being axially positioned between the tapered portion of the first external thread portion (12) and the free end of the first convex portion (6), such that the cylindrical portion is at least partially disposed on the sealing lip.

2. The connecting device (1) according to claim 1, wherein, The first external thread portion (12) includes a thread portion having an insertion side (19) and a bearing side (20), the insertion side (19) being oriented toward the free end of the first convex portion (6), and the bearing side (20) being oriented in the opposite direction. The first external thread portion (12) or the second external thread portion (11) includes an axial pressure region (21) extending from the free end of the first convex portion (6) between a first region (22) and a second region (23). In the first region (22), axial interference begins between the insertion side (19) and the corresponding surface of the first internal thread portion (10). Starting from the second region (23), the insertion side (19) no longer interferes with the corresponding surface of the first internal thread portion (10), while the bearing side (20) interferes with the corresponding region of the first internal thread portion (10).

3. The connecting device (1) according to claim 2, wherein, The axial pressure region (21) has between one and four teeth.

4. The connecting device (1) according to any one of claims 1 to 3, wherein, The connecting sleeve (4) has an additional axial stop surface (24) that protrudes radially toward the inside of the connecting sleeve (4) from an intermediate portion (18) located between the first internal thread portion (10) and the second internal thread portion (9), and the sealing lip portion (16) is designed to contact the additional axial stop surface (24) in the connecting position.

5. The connecting device (1) according to claim 4, wherein, The end teeth of the first external thread portion (12) are designed to contact the additional axial stop surface (24) in the connection position, the radial height of the additional stop surface (24) being equal to or greater than half the radial height of the end teeth.

6. The connecting device (1) according to claim 1, wherein, The second external thread portion (11) is truncated tapered, and the second internal thread portion (9) is truncated tapered.

7. The connecting device (1) according to claim 1, wherein, The connecting sleeve (4) has a threadless intermediate portion (18) arranged between the first internal thread portion (10) and the second internal thread portion (9).

8. The connecting device (1) according to claim 7, wherein, The axial length of the middle portion (18) is equal to or greater than one pitch of the first external thread portion (12).

9. The connecting device (1) according to claim 7, wherein, In the connection position, one end of the intermediate portion (18) is axially positioned between the free end of the sealing lip (16) and the first axial stop surface (15).

10. The connecting device (1) according to claim 7, wherein, The intermediate portion (18) is positioned such that when the first axial stop surface (15) and the second axial stop surface (13) are in contact with each other in the connection position, the sealing lip (16) is in radial contact with the outer sealing surface (14) on the radially inner side of the intermediate portion (18).

11. The connecting device (1) according to claim 1, wherein, The first tubular element (3), the second tubular element (2) and the connecting sleeve (4) are made of steel.

12. The connecting device (1) according to claim 1, wherein, Compared to the degree of interference between the second external thread (11) and the second internal thread (9), the first external thread (12) and the first internal thread (10) come into contact with a greater degree of interference in the interference area.

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