Threaded tubular connector

Abstract

The invention relates to a tubular connection (1) comprising a first tubular part (2) and a second tubular part (3), the tubular parts (2, 3) each comprising a thread (8) having a variable thread pitch and sealing surfaces (9, 7, 13, 15), the threads (8, 14) engaging with each other when the tubular connection (1) is in the installed state, the sealing surfaces (7, 9, 13, 15) being in sealing contact when the tubular connection (1) is in the installed state, the tubular connection (1) comprises a reference mark (26) having an optimal relative position between the tubular parts (2, 3), characterized in that the optimal relative position corresponds to a nominal optimal relative position to which a correction is applied, the correction depends on a characteristic of the one of the first tubular part (2) and the second tubular part (3), on which the reference mark is arranged, and on a target torque of the tubular connection (1).

Description

Field of the Invention

[0001] The present invention relates to the field of threaded connectors for tubular components used, for example, in drilling, the exploitation of oil and gas wells, the transportation of oil and gas, the storage of fluids, as well as in the fields of geothermal energy or CO2 capture. Background Art

[0002] Threaded connectors for tubular components, such as those used in the production string of an oil and gas well, comprise tubular components for transporting oil, gas or other fluids that are sealingly joined together in pairs. Each of these joined tubular components has a respective threaded end. This threaded end is produced on the inner surface of the tubular component in the case of a threaded end called female (or "box type"), or on the outer surface of the tubular component in the case of a threaded end called male (or "pin type"). These threaded ends are complementary in such a way as to allow the tubular components to be screwed together in pairs.

[0003] The tubular components of the threaded connector are assembled under predetermined stress conditions to meet the fastening and sealing requirements imposed by the service conditions. Assembled in this way, the tubular components form a so-called joint or connection in the assembled state.

[0004] In addition, in use, these threaded connectors are subjected to axial tensile and / or compressive stresses, internal and / or external fluid pressures, bending or torsion, and these forces can combine and have fluctuating intensities. Despite the stresses and the harsh operating conditions in the field, it is still necessary to ensure the tightness of these threaded connectors.

[0005] The threaded connector must also be able to be screwed and unscrewed several times without compromising its performance, in particular without being damaged due to jamming. After unscrewing, these components can be reused under other operating conditions.

[0006] Document US20070158943 describes a threaded connector with self-locking threads having teeth of variable width, i.e., having interference between the sides of the teeth of the thread. The threaded connector described in US20070158943 also includes a metal-to-metal sealing surface. Such a connector provides high torque while ensuring good sealing.

[0007] As stated in the said document, it is important that the two tubular components forming the connector have a controlled relative position to ensure good interaction between the sealing surfaces and thus ensure good sealing of the connector. In particular, it is important that the screwing of the two tubular components allows sufficient interference between the two sealing surfaces to ensure the sealing of the connector while preventing excessive interference that could lead to jamming and / or damage to the sealing surfaces.

[0008] To ensure the correct relative positioning of the tubular components forming the connection, the connection described in US20070158943 also includes complementary stop surfaces located on the tubular components. The abutment of these stop surfaces makes it possible to ensure the correct relative positioning between the tubular components forming the connection. However, such stop surfaces occupy a significant radial space and thus limit the space available for other elements of the tubular components. Such stop surfaces also constitute stress concentration areas that can disrupt the normal function of the connection. Therefore, these stop surfaces are not entirely satisfactory for ensuring the correct relative positioning of the tubular components in a connection that includes teeth with variable widths, interfering threads, and a dedicated sealing surface.

[0009] To avoid using stop surfaces, it is also known to use reference marks, such as visual reference marks, on one of the tubular components of the connection. Typically, the tubular components are screwed together until a target tightening torque, hereinafter referred to as the target torque, is reached, which corresponds to the torque obtained when the threaded connection is in the assembled state. If the end of the tubular component without the visual reference mark is aligned with the visual reference mark in the assembled state of the connection, the connection is considered to have satisfactory operating performance and is thus accepted. Conversely, if the end of the tubular component without the visual reference mark is not aligned with the visual reference mark in the assembled state of the connection, the threaded connection is considered to have unsatisfactory operating performance and is thus rejected.

[0010] Such visual reference marks are arranged on one of the tubular components according to the nominal position of the reference mark. The nominal position of the reference mark is determined in a manner similar to other parameters of the connection, i.e., by means of the dimensions defined in the specifications of the connection and the tubular components. More specifically, the reference point is defined by the nominal optimal relative position between the tubular components and the nominal axial positioning tolerances on either side of the nominal optimal relative position.

[0011] However, as is the case with other parameters of the connection and the tubular components, the nominal position of the reference mark is affected by manufacturing tolerances. Typically, the nominal optimal relative position and the nominal axial positioning tolerances are affected by manufacturing tolerances in terms of their position on the tubular components.

[0012] In addition, since other structural features of the tubular components are also affected by manufacturing tolerances, there is also uncertainty regarding the exact relative position of the tubular components with respect to the reference mark when the connection is in the assembled state.

[0013] Specifically, tolerances involved in thread manufacturing, interference at the target tightening torque, the position of the sealing surfaces, etc. may result in the following situation: the target tightening torque is reached, the end of the tubular component without a reference mark is aligned with the reference mark, but the sealing surfaces are not correctly positioned, thus failing to ensure a good seal at the connection. Therefore, even if the sealing surfaces are not correctly positioned relative to each other, due to manufacturing tolerances, the position of the reference mark corresponds to the position of the end of the tubular component not including the reference mark, and an unsatisfactory assembly state of the connection may be accepted. Such incorrect relative positioning of the sealing surfaces may result in too little interference or, conversely, too much interference between the sealing surfaces, leading to sealing defects or jamming, or even damage to the sealing surfaces.

[0014] Conversely, it may occur that the target tightening torque is reached and, even if the sealing surfaces are correctly positioned, the free end of the tubular component not including the reference mark is not aligned with the reference mark. In other words, due to manufacturing tolerances, there is a non - correspondence between the position of the reference mark and the end of the tubular component not including the reference mark, so satisfactory assembly conditions may be rejected.

[0015] Therefore, there is a need for a connection that reliably provides high torque and a good seal. Summary of the Invention

[0016] The concept underlying the present invention is to provide a connection that reliably provides high torque and a good seal. In particular, the concept underlying the present invention is to position, in an accurate and reliable manner, a reference mark for relative positioning between two tubular components of the connection. Therefore, the concept underlying the present invention is to consider the structural elements of a threaded connection for determining the accurate and reliable positioning of a reference mark for relative positioning between tubular components. The concept underlying the present invention is to use the actual characteristics of the connection and the tubular components to determine the position of the reference mark.

[0017] To this end, the present invention provides a tubular connection, which includes a first tubular component and a second tubular component,

[0018] The first tubular component includes a first thread and a first sealing surface, and the first thread has a variable tooth width,

[0019] The second tubular component includes a second thread and a second sealing surface, and the second thread has a variable tooth width,

[0020] The first thread and the second thread engage in the assembled state of the tubular connection, and the first sealing surface and the second sealing surface are in sealing contact in the assembled state of the tubular connection.

[0021] One of the first tubular member and the second tubular member includes a reference mark which has an optimum relative position between the first tubular member and the second tubular member.

[0022] Characterized in that the optimum relative position of the reference mark is a corrected optimum relative position, the corrected optimum relative position corresponding to a nominal optimum relative position to which a correction is applied, the correction depending on the characteristics of the one of the first tubular member and the second tubular member in which the reference mark is arranged and the target torque of the tubular connection.

[0023] A thread with a variable tooth width has teeth, the width of which taken along the axial direction of the tubular member increases in a direction oriented from the free end of the member towards the body of the tubular member. This tooth width is taken at the same height on consecutive teeth other than imperfect teeth, for example at the level of the top width of the teeth. This variation in tooth width is achieved by means of a difference in the thread pitch of the tooth flanks, for example, the thread pitch of the insertion flank of the tooth being greater than the thread pitch of the load flank of the tooth.

[0024] By means of these features, the reference mark for controlling the relative position between the first tubular member and the second tubular member in the assembled state of the connection is arranged on the corresponding tubular member with satisfactory precision. In particular, this position of the reference mark is determined by the actual characteristics of the tubular member and the tubular connection, rather than by a theoretical position that does not take into account the manufacturing tolerances of the reference mark and the other characteristics of the tubular member and the connection.

[0025] Therefore, the reference mark arranged according to the above features makes it possible to ensure a proper optimum relative positioning of the first tubular member and the second tubular member. In particular, such a reference mark arranged according to the above features makes it possible to ensure a satisfactory relative positioning of the first sealing surface and the second sealing surface, thus ensuring a satisfactory seal of the connection in the assembled state. In addition, this correct positioning of the reference mark and thus of the sealing surface makes it possible to ensure that there is no damage caused by excessive interference on the sealing surface.

[0026] This corrected optimum relative positioning of the tubular members also makes it possible to ensure that the male tubular member is not inserted too far into the female tubular member. Such excessive insertion may cause the tubular connection to jam. In addition, such excessive insertion may cause the end of the male tubular member to deform radially inwards, which may prevent the passage of a control tool ("pig").

[0027] This reference point with the corrected optimal relative position also makes it possible to ensure a satisfactory screwing of the first tubular part and the second tubular part without having to follow a screwing curve. Specifically, screwing the tubular parts until the distal end of the tubular part that does not include the reference mark reaches the relative position at the reference mark is sufficient to ensure that the tubular connection is in a satisfactory assembled state.

[0028] The connection according to the invention advantageously makes it possible to withstand high levels of tensile and compressive forces in a simple and reliable manner, and such a connection does not require the presence of stop surfaces to withstand high levels of tensile and compressive forces.

[0029] According to an embodiment, such a tubular connection may include, individually or in combination, one or more of the following features.

[0030] According to an embodiment, the correction is based on the outer diameter of the one of the first tubular part and the second tubular part on which the reference mark is arranged.

[0031] According to an embodiment, the correction is based on the radial thickness of the one of the first tubular part and the second tubular part on which the reference mark is arranged.

[0032] According to an embodiment, the correction is based on the thread pitch of the one of the first tubular part and the second tubular part on which the reference mark is arranged. According to an embodiment, this thread pitch is the thread pitch of the insertion side of the thread belonging to the one of the first tubular part and the second tubular part that includes the reference mark. According to an embodiment, this thread pitch is the thread pitch of the load side of the thread belonging to the one of the first tubular part and the second tubular part that includes the reference mark.

[0033] According to an embodiment, the correction is based on the target torque of the tubular connection.

[0034] Preferably, the correction satisfies the following equation:

[0035]

[0036] where ST is the tolerance threshold, OD is the outer diameter of the one of the first tubular part and the second tubular part that includes the reference mark, Wt is the thickness of the one of the first tubular part and the second tubular part that includes the reference mark, CC is the target torque of the tubular connection, PdF is the thread pitch of the thread belonging to the one of the first tubular part and the second tubular part that includes the reference mark, preferably the maximum thread pitch among the thread pitch of the load side and the thread pitch of the insertion side, for example the thread pitch of the insertion side or the thread pitch of the guiding side.

[0037] According to an embodiment, the first thread includes a plurality of first teeth having a width taken along the longitudinal axis of the tubular connector, the width increasing in a first direction along the axis of the tubular connector.

[0038] According to an embodiment, the second thread includes a plurality of second teeth having a width taken along the longitudinal axis of the tubular connector, the width increasing in a second direction along the axis of the connector, the first direction being opposite to the second direction.

[0039] Preferably, the first direction is oriented from the distal end of the first tubular member towards the body of the first tubular member. Further, the second direction is oriented from the distal end of the second tubular member towards the body of the second tubular member.

[0040] According to an embodiment, the corrected optimal relative position of the reference marks defines the optimal axial position of the distal end of the other of the first tubular member and the second tubular member. In other words, the reference marks define, by means of the corrected optimal relative position on one of the tubular members, the position at which the distal end of the other tubular member must stop in order to obtain a satisfactory tubular connector in the assembled state.

[0041] According to an embodiment, the tubular connector includes a lower tolerance zone.

[0042] This lower tolerance zone makes it possible to define a zone of the relative position between the tubular members in which the loss of interference between the sealing surfaces is acceptable without significantly damaging the normal function of the tubular connector. For example, it can be considered that a loss of interference of about 30% between the first sealing surface and the second sealing surface is acceptable compared to the nominal interference in the assembled state of the connector, i.e., at the target torque. In such a case, it can be considered that a tubular connector in the assembled state having at least 70% interference between the first sealing surface and the second sealing surface is acceptable. This acceptable loss of interference can be adjusted according to the circumstances, for example according to the shape of the first sealing surface and / or the second sealing surface, the presence of one or more other seals in the tubular connector, the expected use conditions or any other reason.

[0043] According to an embodiment, the lower tolerance zone is determined on the one hand by the corrected optimal relative position of the reference marks and on the other hand by a lower correction limit, the lower tolerance zone extending a corresponding distance from the corrected optimal relative position to the lower correction limit in the direction of the distal end of the said one of the first tubular member and the second tubular member that includes the reference marks.

[0044] This lower limit can be defined in many ways. For example, this lower limit can be arbitrarily defined based on statistics considered to be acceptable lower limits. Preferably, this lower limit is determined according to the interference between the first sealing surface and the second sealing surface. Ideally, this lower limit is determined based on the interference between the first sealing surface and the second sealing surface on the one hand and the interference between the first thread and the second thread on the other hand.

[0045] According to an embodiment, the corrected lower limit satisfies the following equation:

[0046]

[0047] where SI is the interference percentage regarding the seal, R1 is the acceptable interference loss, ST1 is the inclination of the first sealing surface, and ST2 is the inclination of the second sealing surface.

[0048] In the case of a flat sealing surface, the inclination ST1 or ST2 of such a flat sealing surface corresponds to the angle formed between the flat sealing surface and the longitudinal axis of the tubular connector. In the case of a toroidal sealing surface, the inclination of the toroidal sealing surface corresponds to the angle formed by the straight line connecting the joining points of the toroidal sealing surface with the parts of the tubular component axially located on either side of the toroidal sealing surface.

[0049] According to an embodiment, the corrected lower limit is equal to the minimum between a first lower limit and a second lower limit, and the first lower limit and the second lower limit satisfy the following equations:

[0050] (1) and

[0051] (2) If then

[0052] the second lower limit = 0, and

[0053] If then

[0054]

[0055] where SI is the interference percentage regarding the seal, R1 is the acceptable tolerance loss, ST1 is the inclination of the first sealing surface, ST2 is the inclination of the second sealing surface, and TTdeg is the inclination of one of the first thread and the second thread, and one of the first thread and the second thread is arranged on the tubular component including the reference mark, and Ti is the nominal interference between the first thread and the second thread under the target torque.

[0056] Such a lower limit takes into account on the one hand the interference between the sealing surfaces and on the other hand the interference between the threads, such that a very precise lower limit can be determined, thereby precisely ensuring that when the distal end of the tubular component without the reference mark is radially aligned with the reference mark between the corrected optimal relative position and the lower tolerance zone in the assembled state of the tubular connection, the minimum interference between the sealing surfaces is ensured.

[0057] In the case of a tubular connection in which the top and / or root of its thread teeth are inclined with respect to the longitudinal axis of the connection, the inclination of the thread corresponds to the inclination of the top and / or root. In the case of a tubular connection in which the top and root of its thread teeth are parallel to the longitudinal axis of the tubular connection, the inclination of the thread corresponds to the inclination of the straight line passing through the same points of the roots or tops of the consecutive teeth, and teeth with singularities, such as imperfect teeth that do not allow the definition of corresponding points on this straight line, are ignored in the definition of this inclination.

[0058] According to an embodiment, the tubular connection further includes an upper tolerance zone.

[0059] Such an upper tolerance zone makes it possible to define the zone of the relative position between the tubular components, thereby ensuring that damage is not caused due to excessive interference between the sealing surfaces. Additionally, this upper tolerance zone ensures that the tubular connection is not deformed inwardly due to the tubular components being screwed together excessively, as such deformation would hinder the passage of a control tool ("drift").

[0060] According to an embodiment, the upper tolerance zone is determined on the one hand by the corrected optimal relative position of the reference mark and on the other hand by an upper limit, and the upper tolerance zone extends a corresponding distance from the corrected optimal relative position to the upper limit in the direction of moving away from the free end of the one of the first tubular component and the second tubular component that includes the reference mark.

[0061] The upper limit can be defined in many ways. For example, the upper limit can be arbitrarily defined based on statistical data considered to be an acceptable upper limit. Preferably, the upper limit is determined according to the interference between the first sealing surface and the second sealing surface. Ideally, the upper limit is determined on the one hand based on the interference between the first sealing surface and the second sealing surface and on the other hand based on the interference between the first thread and the second thread.

[0062] According to an embodiment, the upper limit satisfies the following equation:

[0063]

[0064] where SI is the interference percentage regarding sealing, R2 is the acceptable tolerance loss, ST1 is the inclination of the first sealing surface, and ST2 is the inclination of the second sealing surface.

[0065] According to an embodiment, the upper limit is equal to the minimum between a first upper limit and a second upper limit, and the first upper limit and the second upper limit satisfy the following equations:

[0066] (3) and

[0067] (4) If then

[0068] the second upper limit = 0, and

[0069] If then

[0070]

[0071] wherein, SI is the interference percentage regarding sealing, R2 is the acceptable tolerance loss, ST1 is the inclination of the first sealing surface, ST2 is the inclination of the second sealing surface, and TTdeg is the inclination of one of the first thread and the second thread, one of the first thread and the second thread is arranged on a tubular component including a reference mark, and Ti is the nominal interference between the first thread and the second thread under the target torque of the connector.

[0072] According to an embodiment, the first tubular component has a plurality of first sealing surfaces, and the second tubular component has a plurality of second sealing surfaces.

[0073] In the case of a plurality of sealing surfaces on each tubular component in the tubular components, the lower limit and the upper limit are defined as described above for each sealing area in the sealing area of the tubular connector, and such a sealing area is formed by the interaction of one of the first sealing surfaces and one of the second sealing surfaces. Then, the lower tolerance area is defined by the corrected optimal relative position and the minimum lower limit in the set of lower limits. Similarly, then, the upper tolerance area is defined by the corrected optimal relative position and the minimum upper limit in the set of upper limits. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] With reference to the accompanying drawings, the present invention will be better understood according to the following description of several specific embodiments of the present invention provided only in a non-limiting illustrative manner, and other objects, details, features and advantages of the present invention will become more apparent.

[0075] Figure 1 Figure 1 is a cross-sectional view of a tubular connector according to an embodiment of the present invention.

[0076] Figure 2 Figure 2 schematically depicts Figure 1 ​​​​The region of the tubular connector shown in [description], the region including reference marks for the relative positioning of the tubular components.

[0077] Figure 3 Figure 3 Schematically depicts Figure 1 A first variant of the tubular connector shown in [description], depicting the region of the variant, the region including reference marks for the relative positioning of the tubular components.

[0078] Figure 4 Figure 4 Schematically depicts Figure 1 A second variant of the tubular connector shown in [description], depicting the region of the variant, the region including reference marks for the relative positioning of the tubular components. Detailed Description

[0079] In the description, the drawings, and the claims, axis X corresponds to the axis of rotation of the tubular components in the assembled state of the tubular connector, and axis X also defines the axis of the tubular connector. By convention, the "radial" orientation is oriented orthogonally to axis X and the "axial" orientation is oriented parallel to axis X.

[0080] The terms "outer" and "inner" are used to define the relative position of an element with respect to axis X. Thus, an element closer to axis X is considered an inner or radially inner element, as opposed to an element that is considered an outer or radially outer element and is located on the periphery in the radial direction.

[0081] Oil, gas, or other extraction requires a large number of pairs of connected pipes to form a pipe string in an extraction well. Since these pipes are subjected to many stresses during both their installation and their operation, these pipes meet standards to avoid any damage and any leakage into the environment.

[0082] Figure 1 A cross-sectional view of a tubular connector 1 according to an embodiment of the present invention is shown. The tubular connector 1 is formed by assembling a first tubular component 2 with a second tubular component 3.

[0083] The first tubular component 2 includes a first body 4 and a first connection portion 5. The first connection portion 5 is formed on the outer surface of the first tubular component 2, and the first tubular component 2 is thus referred to as a "male part" (or "pin part"). The first connection portion 5 successively includes a first outer sealing surface 7, a first thread 8, a first inner sealing surface 9, and then the first free end 6 of the first tubular component 2 from the first body 4 to the first free end 6 of the first tubular component 2.

[0084] ​​​​Similarly, the second tubular member 3 includes a second body 10 and a second connecting portion 11. The second connecting portion 11 is formed on the inner surface of the second tubular member 3, and the second tubular member 3 is thus referred to as a "female member" (or "box member"). The second connecting portion 11 sequentially includes a second inner sealing surface 13, a second thread 14, a second outer sealing surface 15, and then the second free end 12 from the second body 10 to the second free end 12 of the second tubular member 3.

[0085] As Figure 1 shown, the first thread 8 includes a plurality of first teeth 16. The first teeth 16 have a width taken parallel to the axis X at the same radial tooth height on each of the first teeth 16, and this width is variable along the axis X. More specifically, the first teeth 16 have an increasing width along the axis X in a first direction oriented from the first free end 6 towards the first body 4.

[0086] The first teeth 16 respectively have a first root 17, a first insertion side 18, a first top 19, and a first load side 20. The first insertion side 18 faces the first free end 6. The first load side 20 faces the first body 4.

[0087] Similarly, the second thread 14 includes a plurality of second teeth 21 with variable tooth widths, and the second teeth 21 have an increasing width in a second direction oriented from the second free end 12 towards the second body 10, so the first direction and the second direction are opposite with respect to the axis X. Similarly, the second teeth 21 have a second root 22, a second insertion side 23 facing the second free end 12, a second top 24, and a second load side 25 facing the second body 10.

[0088] Figure 1 The assembled state of the tubular connector 1 is shown. This assembled state is obtained by screwing the first tubular member 2 and the second tubular member 3 together. During this screwing, the first teeth 16 engage with the second teeth 21. More specifically, in the assembled state, the first teeth 16 and the second teeth 21 engage in an interfering manner. Thus, in the assembled state, the first insertion side 18 interferes with the second insertion side 23, and the first load side 20 interferes with the second load side 25.

[0089] Similarly, in this assembled state, the first inner sealing surface 9 and the second inner sealing surface 13 are in interfering contact to ensure good sealing of the tubular connector 1, especially for the fluid circulating inside the tubular connector 1. The first outer sealing surface 7 and the second outer sealing surface 15 are also in interfering contact to ensure good sealing of the tubular connector 1, especially for the fluid outside the tubular connector 1.

[0090] To ensure the correct relative positioning of the first tubular member 2 and the second tubular member 3 in the assembled state, and in particular the correct relative positioning of the sealing surfaces 7, 9, 13 and 15, a reference mark 26 is arranged on the first tubular member 2. More specifically and as shown in Figure 2 the reference mark 26 is arranged on the outer surface of the first body 4.

[0091] The reference mark 26 includes a nominal optimum relative position, i.e. a theoretical position defined in the specifications intended for the manufacture of the first tubular member 2, which nominal optimum relative position is referred to as the nominal position in the remainder of the description. This nominal position defines the relative position between the first tubular member 2 and the second tubular member 3, and more specifically the relative position between the second free end 12 and the first tubular member 2, in which nominal position the various elements of the first tubular member 2 and the second tubular member 3, and in particular the sealing surfaces 7, 9, 13 and 15, are positioned in such a way as to ensure the optimum functioning of the tubular connection 1.

[0092] The reference mark 26 also includes a nominal lower limit and a nominal upper limit, which nominal lower limit and nominal upper limit define on either side of the nominal position an acceptable region for the relative positioning between the tubular members 2 and 3. In the assembled state of the connection, the theoretical presence of the second free end 12 in a straight line in the radial direction with these relative positioning regions theoretically guarantees the functioning of the tubular connection 1, which functioning is not optimum but remains within acceptable operating limits. For example, these nominal lower limit and nominal upper limit can define an acceptable loss of interference between the sealing surfaces 7, 9, 13 and 15, or conversely, define the maximum interference limit that can be accepted with respect to the optimum interference.

[0093] However, the reliability of this reference mark 26 is affected by the manufacturing tolerances of the first tubular member 2 and the second tubular member 3. In particular, the reference mark 26 is affected by the manufacturing tolerances of the threads 8 and 14, which manufacturing tolerances affect the degree of interference between the sides 18, 20, 23 and 25, and thus affect the relative position between the first tubular member 2 and the second tubular member 3. The nominal position, the nominal upper limit and the nominal lower limit defining the reference mark 26 are themselves also affected by manufacturing tolerances. In addition, the sealing surfaces 7, 9, 13 and 15 are also affected by manufacturing tolerances. Therefore, there is uncertainty as to the reliability of the reference mark 26 in indicating the correct relative positioning of the sealing surfaces 7, 9, 13 and 15.

[0094] The influence of manufacturing tolerances on the reference mark 26 may result in the acceptance of the tubular connection 1 because, even if the sealing surfaces 7, 9, 13, and 15 do not interact in an acceptable manner, the second free end 12 is arranged to be in a straight line with the reference mark 26 in the radial direction. Conversely, the influence of manufacturing tolerances on the reference mark 26 may result in the rejection of the tubular connection 1 because, even if the sealing surfaces 7, 9, 13, and 15 interact in an acceptable manner, the second free end 12 is not in a straight line with the reference mark 26 in the radial direction.

[0095] To avoid this, according to the present invention, the reference mark 26 is positioned according to the actual parameters of the tubular components 2 and 3. Generally, the reference mark 26 is positioned on the first tubular component 2 according to the parameters of the first tubular component 2 and the second tubular component 3 after their manufacture, and these parameters are measured, calculated, or obtained by any other means. Therefore, the parameters used in the following equations related to one of the tubular components 2 or 3 are the actual parameters of the tubular component 2 or 3, such as those measured after manufacture. However, the parameters related to the tubular connection 1, such as the target torque CC, the interference percentage SI regarding sealing, or the interference Ti between the first thread 8 and the second thread 14, are the nominal values, i.e., the theoretical values, of the tubular connection 1. These nominal values are obtained at the target torque in the case of interference.

[0096] In particular, the corrected optimal relative position 27 is defined. The reference mark 26 is arranged on the first tubular component not according to the nominal position but according to this corrected optimal relative position 27, hereinafter referred to as the correction position 27. This correction position 27 is defined not only according to the nominal position defined in the application document but also according to the outer diameter OD of the first tubular component 2, the thickness Wt of the first tubular component 2, and the thread pitch Pdf of the first thread 8. After the manufacture of the first tubular component 2, the outer diameter OD, the thickness Wt, and the thread pitch Pdf are measured, calculated, or obtained by any other means on the first tubular component 2; therefore, these are the actual parameters of the first tubular component.

[0097] The correction position 27 is also positioned according to the target torque CC of the tubular connection 1.

[0098] Therefore, a positioning correction for calculating the optimal relative position is performed for the reference mark. This correction satisfies the following equation:

[0099]

[0100] where ST is the tolerance threshold, OD is the outer diameter of the first tubular component 2, Wt is the thickness of the first tubular component 2, CC is the target torque of the tubular connection 2, and PdF is the thread pitch of the first thread 8, preferably the larger of the thread pitch on the load side and the thread pitch on the insertion side of the first thread 8.

[0101] The tolerance threshold ST can be determined in many ways. Preferably, the tolerance threshold ST can be arbitrarily determined, for example, determined at the value 96000, which value is applicable to all connectors according to the present invention. The tolerance threshold ST can also be calculated by analyzing the inclination of the thread and the thread pitch, in particular the "wedge ratio", i.e., the difference between the thread pitch on the insertion side and the thread pitch on the load side.

[0102] This equation enables the displacement distance relative to the nominal position to be obtained. Thus, the corrected position 27 is obtained by applying an offset having a value corresponding to the obtained correction to the nominal position, and thus the position where the reference mark 26 is arranged on the first tubular member 2 is obtained.

[0103] This correction allows the reference mark 26 to be positioned precisely and reliably. In particular, the corrected position 27 takes into account the manufacturing tolerances of the first tubular member 2 and the tubular connector 1, such that the corrected position 27 corresponds to the relative position of the second free end 12 with respect to the reference mark 26, in which the sealing surfaces 7, 9, 13, and 15 are actually correctly positioned to ensure the sealing of the tubular connector 1.

[0104] In addition, the reference mark 26 arranged based on the corrected position 27 includes a correction lower limit 28 and a correction upper limit 29 that can be determined in various ways.

[0105] For example, the correction lower limit 28 and / or the correction upper limit 29 can be determined by the nominal lower limit and / or the nominal upper limit, respectively. In this case, the reference mark 26 includes an upper tolerance region and a lower tolerance region determined by the corrected position 27 and these nominal limits.

[0106] Alternatively, the correction lower limit 28 and / or the correction upper limit 29 can be determined based on acceptable limit statistics.

[0107] Preferably, like the corrected position 27, the correction lower limit 28 and / or the correction upper limit 29 are also determined based on the actual structural parameters of the tubular connector 1 to further improve the reliability and accuracy of the reference mark 26.

[0108] Therefore, the correction lower limit 28 is advantageously determined according to the desired minimum interference between the sealing surfaces 7, 9, 13, and 15. Similarly, the correction upper limit 29 is advantageously corrected according to the desired interference between the sealing surfaces 7, 9, 13, and 15.

[0109] Ideally, the lower limit is determined not only based on the desired minimum interference between the sealing surfaces 7, 9, 13, and 15, but also based on the interference between the threads 8 and 14. Similarly, ideally, the corrected upper limit 29 is determined not only based on the desired interference between the sealing surfaces 7, 9, 13, and 15, but also based on the interference between the threads 8 and 14.

[0110] In the case of a connector including a plurality of seals as shown in Figure 1 the corrected lower limit is determined for each of the seals in the seal assembly in order to obtain a plurality of corrected lower limits. Then, the corrected lower limit for defining the reference point 26 is the smallest corrected lower limit among the plurality of corrected lower limits. Similarly, the corrected upper limit is calculated for each of the seals in the seal assembly, and the corrected upper limit for defining the reference 26 is the smallest corrected upper limit among the plurality of corrected upper limits obtained based on the plurality of seals.

[0111] Thus, in Figure 1 the case of a tubular connector as shown in including an inner seal formed by the first inner sealing surface 9 and the second inner sealing surface 13 and an outer seal formed by the first outer sealing surface 7 and the second outer sealing surface 15, the corrected limit is determined for the inner seal and the corrected limit is determined for the outer seal. Then, the corrected lower limit 28 of the reference numeral 26 is the smallest corrected lower limit among those corrected lower limits determined for the inner seal and the outer seal. Similarly, then, the corrected upper limit 29 of the reference numeral 26 is the smallest corrected upper limit among those corrected upper limits determined for the inner seal and the outer seal.

[0112] The position of the corrected lower limit and the corrected upper limit with respect to the sealing area is generally described below, and the following description can be applied to each of the different seals.

[0113] According to an embodiment considering the actual interference between the sealing surfaces, the corrected lower limit 28 satisfies the following equation:

[0114]

[0115] where SI is the interference percentage with respect to sealing, R1 is the acceptable tolerance loss between the sealing surfaces, ST1 is the inclination of the first sealing surface, and ST2 is the inclination of the second sealing surface.

[0116] Thus, such a corrected lower limit 28 takes into account the influence of the desired actual interference between the sealing surfaces to accept or reject the tubular connector 1.

[0117] In the case of a flat sealing surface, the inclination of such a flat sealing surface corresponds to the angle formed between the flat sealing surface and the axis X of the tubular connector 1.

[0118] In the case of a toroidal sealing surface, the inclination of the toroidal sealing surface corresponds to the angle formed by a straight line connecting the joining points of the toroidal sealing surface with the portions of the tubular member axially located on either side of the toroidal sealing surface.

[0119] The acceptable interference loss between the sealing surfaces can be determined based on the shape of the sealing surfaces, the desired performance of the tubular connection 1, or any other reason. Such an interference loss between the sealing surfaces is, for example, 30%, that is, a minimum interference of 70% is ensured by correcting the lower limit.

[0120] Similarly, the upper limit satisfies the following equation:

[0121]

[0122] where SI is the interference percentage regarding the seal, R2 is the maximum acceptable interference between the sealing surfaces, ST1 is the inclination of the first sealing surface, and ST2 is the inclination of the second sealing surface.

[0123] The maximum acceptable interference between the sealing surfaces can be determined based on the shape of the sealing surfaces, the performance of the desired tubular connection, or any other reason. Such a maximum acceptable interference between the sealing surfaces is, for example, 40%.

[0124] Therefore, this corrected upper limit takes into account the influence of the desired actual interference between the sealing surfaces to accept or reject the tubular connection 1.

[0125] According to a preferred embodiment that takes into account not only the actual interference between the sealing surfaces but also the interference between the threads, the corrected lower limit is equal to the minimum between a first corrected lower limit and a second corrected lower limit, and the first corrected lower limit and the second corrected lower limit satisfy the following equations:

[0126] (1) and

[0127] (2) If then

[0128] the second lower limit = 0, and

[0129] If then

[0130]

[0131] Wherein, SI is the interference percentage regarding the seal, R1 is the acceptable tolerance loss, ST1 is the inclination of the first sealing surface, ST2 is the inclination of the second sealing surface, and TTdeg is the inclination of the thread corresponding to the tubular member on which the reference mark 26 is arranged, and Ti is the nominal interference between the first thread and the second thread under the target torque of the connector.

[0132] Such a lower correction limit takes into account the interference of the sealing surfaces on the one hand and the interference between the threads on the other hand, so that a very precise lower correction limit can be determined, thereby accurately ensuring a minimum interference in the assembled state of the tubular connector 1.

[0133] Similarly, the upper correction limit is equal to the minimum value between the first upper correction limit and the second upper correction limit, and the first upper correction limit and the second upper correction limit satisfy the following equations:

[0134] (3) And

[0135] (4) If Then

[0136] The second upper limit = 0, and

[0137] If Then

[0138]

[0139] Wherein, SI is the interference percentage regarding the seal, R2 is the acceptable tolerance loss between the sealing surfaces, ST1 is the inclination of the first sealing surface, ST2 is the inclination of the second sealing surface, and TTdeg is the inclination of the thread corresponding to the tubular member on which the reference mark 26 is arranged, and Ti is the nominal interference between the first thread and the second thread under the target torque of the connector.

[0140] In this preferred embodiment, the influence of the desired actual interference between the sealing surfaces and the influence of the actual interference between the threads are taken into account to reliably and accurately accept or reject the tubular connector.

[0141] Figure 1 And Figure 2 Fig. shows the tubular connector 1, wherein the reference mark 26 is arranged on the outer surface of the body 4 of the male first tubular member 2, and the tubular connector can be accepted according to the relative position of the second free end 12 with respect to the reference mark 26. However, the present invention is equally applicable to tubular connectors having other configurations.

[0142] Figure 3 And Figure 4Depicts other configurations of such an example, and the above descriptions regarding reference numeral 26, calibration position 27, calibration lower limit 28, and calibration upper limit 29 equally apply to other configurations of such a tubular connector 1. Among these Figure 3 and Figure 4 , elements that are the same as or perform the same functions as the elements described above regarding Figure 1 and Figure 2 have the same reference numerals. In the following descriptions of Figure 3 and Figure 4 , only the elements that are different from those already described above regarding Figure 1 and Figure 2 are described in detail. Regarding the elements not described regarding Figure 3 and Figure 4 , they are the same as those already described regarding Figure 1 and Figure 2 .

[0143] Figure 3 Depicts the case of a tubular connector 1 referred to as "flush type", that is, the outer diameter of the tubular connector 1 is smaller than 101% of the outer diameters of the tubular members 2 and 3 forming it. In this tubular connector 1, the reference numeral 26 is arranged on the outer surface of the first connection portion 5 of the first tubular member 1. More specifically, the reference numeral 26 is arranged between the first body 4 and the first outer sealing surface (not shown).

[0144] Figure 4 Depicts the case of a tubular connector 1 in which the reference numeral 26 is arranged on the inner surface of the second tubular member 3, that is, on the female tubular member 3. Then, this reference numeral 26 enables the acceptance or rejection of the tubular connector 1 based on the relative position between the reference numeral 26 and the first free end 6. In addition, the reference numeral 26 is then arranged on the inner surface of the second connection portion 11 that is axially located between the second body 10 and the second inner sealing surface 13.

[0145] Regarding Figures 1 to 4 only the elements related to the present invention are described. The tubular connector may also include other features not described above. Thus, for example, Figure 1 the tubular connector shown in includes an outer groove for collecting the grease that can be applied to the tubular member, and the first tubular member may include a chamfer connecting the face of the free end of the first tubular member and the inner surface of the first tubular member, etc.

[0146] The above has described the present invention in the case of a preferred embodiment with reference to Figures 1 to 4 . However, the present invention also encompasses embodiments not shown.

[0147] For example, the present invention is applicable to the case of integral connectors or sleeve-coupled connectors. In integral connectors, the long tubular components have male connecting elements at the first end and female connecting elements at the other end, and these long components are directly assembled in pairs. In sleeve-coupled connectors, the long tubular components have male connecting elements at each end, and the shorter tubular components called couplers have female connecting elements at each end, and the two long tubular components are connected by means of the couplers.

[0148] The connectors can be flush or semi-flush. A flush connector is a connector whose outer diameter is at most equal to 101% of the outer diameter of the body of the tubular component attached to the connector. A semi-flush connector is a connector whose outer diameter is at most equal to 110% of the outer diameter of the body of the tubular component attached to the connector.

[0149] Similarly, the present invention has been described above in the case of single-start threads, and the present invention is also applicable to the case of threads including, for example, several thread regions at several levels.

[0150] The present invention is also applicable to the case of tubular connectors including, for example, one or more sealing regions on either side of the thread and / or including a central sealing region.

[0151] Likewise, the roots and tops of the teeth of the thread can be parallel to the axis of the tubular connector or parallel to the inclination of the thread. Such teeth can have a dovetail profile or a trapezoidal profile.

[0152] The reference marks can be made in various ways. Thus, such reference marks can be made, for example, by knurling, by machining grooves forming visual reference marks, by laser marking, by coating, by stamping reference marks, etc.

[0153] In the case where the tubular connector includes a plurality of first sealing surfaces and a plurality of corresponding second sealing surfaces that form different sealing regions in pairs, the correction lower limit and the correction upper limit are respectively the minimum value between the lower limits calculated for each sealing region in the sealing regions and the minimum value between the upper limits.

[0154] Although the present invention has been described in connection with several specific embodiments, it is obvious that the present invention is by no means limited thereto, and within the scope of the present invention, the present invention includes all technical equivalents of the described devices and their combinations.

[0155] The use of the verb "comprise" or "include" and its combined forms does not exclude the presence of other elements or other steps other than those stated in the claims.

[0156] In a claim, any reference signs in parentheses shall not be construed as limiting the claim.

Claims

1. A tubular connector (1), the tubular connector (1) comprising a first tubular member (2) and a second tubular member (3), The first tubular member (2) comprises a first thread (8) and a first sealing surface (9, 7), the first thread (8) having a variable tooth width, The second tubular member (3) comprises a second thread (14) and a second sealing surface (13, 15), the second thread (14) having a variable tooth width, The first thread (8) and the second thread (14) are engaged in the assembled state of the tubular connector (1), and the first sealing surface (7, 9) and the second sealing surface (13, 15) are in sealing contact in the assembled state of the tubular connector (1), One of the first tubular member (2) and the second tubular member (3) comprises a reference mark (26), the reference mark having an optimum relative position between the first tubular member (2) and the second tubular member (3), Characterized in that, The optimum relative position of the reference mark (26) is a corrected optimum relative position (27), the corrected optimum relative position (27) corresponding to a nominal optimum relative position to which a correction is applied, the correction depending on the characteristics of the one of the first tubular member (2) and the second tubular member (3) in which the reference mark is arranged and the target torque of the tubular connector (1).

2. The tubular connector (1) according to claim 1, Wherein, The correction satisfies the following equation: Where ST is a tolerance threshold, OD is the outer diameter of the one of the first tubular member (2) and the second tubular member (3) that includes the reference mark (26), Wt is the thickness of the one of the first tubular member (2) and the second tubular member (3) that includes the reference mark (26), CC is the target torque of the tubular connector (1), and PdF is the thread pitch of the thread that belongs to the one of the first tubular member (2) and the second tubular member (3) that includes the reference mark (26).

3. The tubular connector (1) according to claim 1 or 2, further comprising a lower tolerance zone.

4. The tubular connector (1) according to claim 3, Wherein, The lower tolerance zone is determined on the one hand by the corrected optimum relative position (27) of the reference mark (26) and on the other hand by a lower correction limit (28), the lower tolerance zone extending a corresponding distance from the corrected optimum relative position (27) to the lower correction limit (28) in the direction of the free ends (6, 12) of the one of the first tubular member (2) and the second tubular member (3) that includes the reference mark (26).

5. The tubular connector (1) according to claim 4, Wherein, The lower correction limit (28) satisfies the following equation: Wherein, SI is the interference percentage regarding the seal, R1 is the acceptable interference loss, ST1 is the inclination of the first sealing surface (7, 9), and ST2 is the inclination of the second sealing surface (13, 15).

6. The tubular connector (1) according to claim 5, wherein, the corrected lower limit is equal to the minimum value between the first lower limit and the second lower limit, and the first lower limit and the second lower limit satisfy the following equations: (1) and (2) If then The second lower limit = 0, and If then wherein, SI is the interference percentage regarding the seal, R1 is the acceptable tolerance loss, ST1 is the inclination of the first sealing surface (7, 9), ST2 is the inclination of the second sealing surface (13, 15), and TTdeg is the inclination of one of the first thread (8) and the second thread (14), one of the first thread (8) and the second thread (14) is arranged on the tubular component including the reference mark (26), and Ti is the nominal interference between the first thread and the second thread.

7. The tubular connector (1) according to one of the preceding claims, further comprising an upper tolerance zone.

8. The tubular connector (1) according to claim 7, wherein, the upper tolerance zone is determined on the one hand by the corrected optimal relative position (27) of the reference mark (26), and on the other hand by the corrected upper limit (29), and the upper tolerance zone extends a corresponding distance from the corrected optimal relative position (27) to the corrected upper limit (29) in a direction moving away from the free end (6, 12) of one of the first tubular component (2) and the second tubular component (3) including the reference mark (26).

9. The tubular connector according to claim 8, wherein, the upper limit satisfies the following equation: wherein, SI is the interference percentage regarding the seal, R2 is the acceptable tolerance loss, ST1 is the inclination of the first sealing surface (7, 9), and ST2 is the inclination of the second sealing surface (13, 15).

10. The tubular connector (1) according to claim 9, wherein, the corrected upper limit (29) is equal to the minimum value between the first upper limit and the second upper limit, and the first upper limit and the second upper limit satisfy the following equations: (3) (4) If then The second upper limit = 0, and If then wherein, SI is the interference percentage regarding the seal, R2 is the acceptable tolerance loss, ST1 is the inclination of the first sealing surface (7, 9), ST2 is the inclination of the second sealing surface (13, 15), and TTdeg is the inclination of one of the first thread (8) and the second thread (14), one of the first thread (8) and the second thread (14) is arranged on the tubular component including the reference mark (26), and Ti is the nominal interference between the first thread and the second thread.

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