TUBULAR SCREW CONNECTION

Description

Technical field

[0001] The invention relates to the field of tubular threaded joints. More particularly, the invention relates to metallic tubular threaded joints used in the oil and gas, energy or storage industry, and in particular for use such as the exploitation of hydrocarbon wells, the transport of hydrocarbons, carbon capture or geothermal energy. Technological background

[0002] The term "threaded joint" herein means an assembly consisting of substantially tubular, metallic components assembled together by screwing. The tubular components may be tubes or any type of connecting part commonly used in the field of the invention, such as sleeves. Such metallic tubular components have an elastic limit preferably greater than or equal to 450 MPa.

[0003] Each tubular component has an end portion with a male threaded area or a female threaded area intended to be screwed with a corresponding end portion of a similar component. Thus assembled, the threaded tubular components constitute what is called a joint or a connection.

[0004] These seals are subjected to a wide variety of axial tensile or compressive stresses, internal or external fluid pressure, bending or even torsion, which may be combined and whose intensity may fluctuate. Sealing must be ensured despite these stresses and despite the harsh operating conditions on site.

[0005] In recent years, the demand of operators in the field of the invention has evolved. Thus, it is increasingly requested by operators that threaded joints have better resistance to all these stresses, in particular when the stress load applied to the joint exceeds the elastic limit of said joint.

[0006] To meet this demand, the prior art described in patent EP3572612: a tubular threaded joint comprising a tubular female end extending from a main body of a first tubular element, and a tubular male end extending from a main body of a second tubular element. This joint has two stepped threaded portions, between which a first stop is arranged. The joint further comprises a second stop formed by a male free end and a female internal shoulder. The threads of the tubular components forming this joint have load flanks and engagement flanks with exactly the same pitch. The disadvantage of such a joint is that axial play remains at the load flanks and / or the engagement flanks of the thread. When such a joint is subjected to high mechanical stresses, there is then a high risk that this axial play will cause leaks.Due to this axial clearance, the greases that are added during coupling, in particular to limit the risk of leakage, are stored in the gaps formed between the load flanks and the engagement flanks. Thus, when such a joint passes from a first tensile stress state to a second compressive stress state, the gaps that were open in the first stress state close, thus opening new gaps between the thread flanks that were in contact in the first stress state but are no longer in the second stress state. Such a passage from one stress state to another causes a movement of the greases from the gaps that were open in the first stress state of the joint, to the gaps that are formed when the joint passes into the second stress state.With such a movement of greases in the thread, the load flanks and the engagement flanks are alternately spaced from each other, then directly in contact, and vice versa, depending on the stress state in which the seal is found. The fact that the thread flanks regularly come into direct contact leads to a significant increase in the risk of seizure, which greatly reduces the service life of the seals. As a result, such seals must be changed frequently, which complicates maintenance for operators while generating additional operational costs. Summary

[0007] In order to overcome the above drawbacks, a first aim of the invention is to significantly reduce the risk of seizure at the level of a threaded joint while improving the resistance of the threaded joint to mechanical stresses. In addition, a second aim of the invention is to reduce the operational costs generated by the use of the threaded joint while simplifying operations on site.

[0008] Thus, the invention provides a threaded joint having a longitudinal axis x, said joint comprising a first tubular component and a second tubular component, the first tubular component and the second tubular component being screwed to each other, the first component comprising a first tube and a male element arranged at one end of said first tube, the male element comprising successively from the first tube to a male internal stop surface of said male element: a male external stop surface, at least a first male threaded portion having a variable-width thread profile with self-locking tightening, and the male internal stop surface, the second component comprising a second tube and a female element arranged at one end of said second tube, the female element comprising successively from the second tube to a female external stop surface of said female element: a female internal stop surface, at least a first female threaded portion having a variable-width thread profile with self-locking tightening, a female lip, and the female external stop surface, a first axial length BSL between the female inner abutment surface and the female outer abutment surface being greater than a second axial length PSL between the male inner abutment surface and the male outer abutment surface, the first axial length BSL and the second axial length PSL being such that a gap is formed between the male outer abutment surface and the female outer abutment surface, said gap being capable of being closed by contact between the male outer abutment surface and the female outer abutment surface when an axial compressive load is applied.

[0009] The gap formed between the male external abutment surface and the female external abutment surface relieves the compressive force exerted on the thread flanks when the load applied in compression exceeds the yield strength of the joint. Thus, when the tubular components are screwed together and an axial compressive load is applied, the male external abutment surface and the female external abutment surface come into contact as soon as the axial compressive load becomes greater than the yield strength of the threads. This has the consequence that the compressive load is immediately distributed on the one hand, on the thread flanks, and on the other hand, on the surfaces of the male and female external abutments. Such a distribution of the load makes it possible to maintain the seal provided by the thread.Such an architecture of the male and female elements thus makes it possible to obtain a joint with better compression performance, particularly after its elastic limit.

[0010] The internal diameter of a seal decreases axially from the outer abutment surfaces to the inner abutment surfaces. Therefore, the surface area of ​​an outer abutment is necessarily greater than the surface area of ​​an intermediate abutment, and an intermediate abutment surface is necessarily greater than an inner abutment surface. Therefore, the fact that the abutment contact is between the outer abutment surfaces allows for a larger abutment contact area and therefore a greater torque capacity than that of a seal whose abutment contact is at an inner or intermediate shoulder. In other words, the fact that the abutment contact is between the outer abutment surfaces allows for the support of greater axial compressive loads compared to abutment contact that would be at an inner or intermediate shoulder.

[0011] Variable width, self-locking threads such as those used in the invention prevent a gap from forming in the thread of the joint. Thus, when the first tubular component and the second tubular component are screwed together and no axial compressive load is applied, the integrity, and in particular the sealing, of the joint is produced entirely by the torque generated by the contact between, on the one hand, the load flanks and the thread engagement flanks of the first tubular component, and on the other hand, the load flanks and the thread engagement flanks of the second tubular component. Therefore, with such a joint, it is not necessary to use greases to achieve sealing, which reduces the amount of grease used and therefore reduces operational costs.On the other hand, due to the absence of axial play between the threads, the risk of seizure during a change of stress state, for example when changing from a tensile state to a compression state, the risk of seizure is almost zero and the service life of such a joint is therefore significantly increased.

[0012] According to one embodiment, the male element comprises a male external housing which extends from the male external abutment surface to the male threaded portion.

[0013] According to one embodiment, the male external abutment surface has an inclination of angle α relative to a first axis y, said first axis y being perpendicular to the longitudinal axis x, and in that the female external abutment surface has an inclination of angle β relative to a second axis y", said second axis y" being perpendicular to the longitudinal axis x, the angles α and β being such that the male external abutment surface and the female external abutment surface are substantially parallel. In other words, the angles α and β are substantially equal.

[0014] Thanks to these characteristics, whatever the value of the angles α and β, the male external stop surface and the female external stop surface are always face to face, so as to present a maximum contact surface between them, which improves the performance of the joint in compression.

[0015] For the sake of clarity, it is hereby specified that, in the present application, any value given to the angle α corresponds to an angle value measured in the trigonometric direction between the male external stop surface and the y axis. In the same way, any value given to the angle β corresponds to an angle value measured in the trigonometric direction between the female external stop surface and the y axis.

[0016] According to one embodiment, the y-axis and the male external abutment surface are coaxial and the y-axis and the female external abutment surface are coaxial. The angles α and β thus formed are either zero angles or flat angles. A zero angle is defined as having a value of 0° and a flat angle is defined as having a value of 180°.

[0017] According to one embodiment, the angles α and β both have either a value of 0° or a value of 180°.

[0018] According to one embodiment, the angles α and β are such that: 0°≤ α ≤30° and 0°≤β≤30°. Beyond 30°, when an axial compressive load is applied to the seal, the lip may begin to flex, which may lead to the lip breaking.

[0019] According to one embodiment, the angles α and β are such that: 0°≤ α ≤10° and 0°≤β≤10°.

[0020] According to one embodiment, the angles α and β are such that: 0°≤ α ≤5° and 0°≤β≤5°.

[0021] When a joint is subjected to an axial compressive load, and in particular when this load exceeds the elastic limit of said joint, the end of the female element tends to undergo a mechanical force oriented radially towards the outside of the tube. This phenomenon tends to reduce the contact surface between the male external stop surface and the female external stop surface, which tends to reduce the compression performance of the joint. Such values ​​of the angles of inclination of the male and female external stop surfaces make it possible to orient the force radially towards the inside of the tube and therefore to avoid this phenomenon.

[0022] According to one embodiment, the gap has an axial length of between 0.10 mm and 1.75 mm. Preferably, the gap has an axial length of between 0.10 mm and 0.82 mm, and even more preferably between 0.10 mm and 0.63 mm. Ideally, the gap has an axial length of between 0.10 mm and 0.50 mm. This allows the gap to close and therefore leads to the improvement of the compressive strength in an optimal manner according to the compression capacities involved in the field of the invention.

[0023] Preferably, the gap has an axial length such that: BSL × (0.5%) / 4 ≤ gap (30) ≤ BSL × 0.7% where BSL is in mm.

[0024] The minimum value makes it possible to reduce the compressive force exerted on the sides of the threads when the load applied in compression exceeds the elastic limit of the joint from 25% of the compression capacity of the joint according to the invention.

[0025] The maximum value makes it possible to reduce the compressive force exerted on the sides of the threads when the load applied in compression reaches 100% of the compression capacity of the joint according to the invention. Definitions

[0026] In the present application, the term "screwed state" means that the tubular components are connected to each other so as to form a joint suitable for use in the field of the invention. By way of example, sealing may be cited as a property necessary for the use of the joint in a field of the invention.

[0027] Axial length means a length that extends and is measured along the longitudinal axis x.

[0028] For the sake of clarity, a way in which the first axial length BSL and the second axial length BSL can be measured is shown here. Thus, the first axial length BSL can be measured from a first female inner radial end to a second female inner radial end. The distance between the points projected radially on the x-axis is therefore taken. Similarly, the second axial length PSL can be measured from a first male inner radial end to a second male inner radial end. The distance between the points projected radially on the x-axis is also taken.

[0029] The term "self-locking tightening thread" means that the thread of the male thread has an axially increasing width in a first direction and the thread of the female thread has an axially increasing width in a second direction, said second direction being opposite to the first direction. The width of self-locking tightening threads, such as those used in the invention, can vary axially, i.e. along the longitudinal axis x, and / or radially, i.e. along an axis perpendicular to the longitudinal axis x. When the width of the threads varies radially, the threads then have a dovetail profile.

[0030] Note that for the so-called "wedge" thread, the threaded portions are offered with a different pitch value for the load flank and for the engagement flank, so that the helix of this type of thread offers a tooth width which increases as the helix turns, from one end to the other, with the hollows defined between the turns of this helix decreasing according to the same progression.

[0031] It should be noted that within the framework of the invention, a stop surface is capable of being in stop contact but is not necessarily so once the joint is in the screwed state. Brief description of the figures

[0032] The invention will be better understood, and other objects, details, characteristics and advantages thereof will appear more clearly during the following description of several particular embodiments of the invention, given solely for illustrative and non-limiting purposes, with reference to the accompanying drawings.

[0033] It should be understood, however, that the present application is not limited to the precise arrangements, structures, features, embodiments and appearance shown. The drawings are not drawn to scale and are not intended to limit the scope of the claims to the embodiment(s) shown in these drawings.

[0034] Therefore, it is to be understood that where features recited in the claims are followed by references, said references are included solely to enhance the understanding of the claims and in no way limit the scope thereof. [ Fig. 1 ] There figure 1 is a diagram of a longitudinal sectional view of a threaded joint whose two tubular components are screwed together, according to one embodiment of the invention (thread not shown). Fig. 2 ] There figure 2is a diagram of a close-up view of detail A of the threaded joint according to the invention of the figure 1 (thread not shown). [ Fig. 3 ] There figure 3 is a diagram of a close-up view of a variant of detail A of a threaded joint according to an embodiment of the invention (thread not shown). Description of the embodiments

[0035] There figure 1 illustrates a longitudinal sectional view of a threaded joint 1 comprising a first tubular component C1 and a second tubular component C2 screwed to each other, according to one embodiment of the invention.

[0036] The first tubular component C1 comprises a first tube 10 and a male element 15. The male element 15 is disposed at one end of the first tube 10. The male element 15 is directly adjacent to the first tube 10. The male element 15 extends axially from a male external abutment surface 11 to a male internal abutment surface 13. The male element 15 successively comprises, from the male external abutment surface 11: a male external housing 14, a male threaded portion 12 having a variable width thread profile with self-locking tightening (not shown), and the male internal abutment surface 13. Although the thread is not described in detail in the present patent application, those skilled in the art may refer to patent EP2999841 which describes a self-locking thread suitable for use in any embodiment of the present invention.

[0037] US patent application 2012 / 286507 A1 discloses a known threaded joint.

[0038] The male outer abutment surface 11 extends radially between a first male outer radial end 16 and a first male inner radial end 18. The first male inner radial end 18 may be a fillet having a radius of curvature between 0.1 mm and 5.0 mm and connecting the male outer abutment surface 11 and the male outer housing 14.

[0039] The male internal abutment surface 13 extends radially between a second male outer radial end 17 and a second male inner radial end 19. The second male outer radial end 17 and the second male inner radial end 19 may be edge breaks or roundings each having a respective radius of curvature and each being directly adjacent to the male internal abutment surface 13.

[0040] The male outer housing 14 extends from the first male inner radial end 18 to the start of the male threaded portion 12. The male outer housing 14 has an unthreaded surface which may have a cylindrical or frustoconical shape. On the figure 1 , the male external housing 14 has a cylindrical unthreaded surface which forms a right angle with the male external abutment surface 11, in other words, the unthreaded surface of the male external housing 14 and the male external abutment surface 11 are orthogonal.

[0041] The male threaded portion 12 is conical, for example with a half-angle of conicity between 0.5° and 5°, preferably between 1° and 3°. The male threaded portion 12 is arranged on the outside of the male element and extends from the male external housing 14 to the second male external radial end 17. The thread (not shown) of the threaded portion 12 has a variable-width thread profile with self-locking tightening, such as a “wedge” type thread in English.

[0042] The second tubular component C2 comprises a second tube 20 and a female element 25. The female element 25 is disposed at one end of the second tube 20. The female element 25 is directly adjacent to the second tube 20. The female element 25 extends axially from a female external stop surface 21 to a female internal stop surface 23. The female element 25 successively comprises, from the female external stop surface 21: a female lip 24, a threaded portion 12 having a variable-width thread profile with self-locking tightening (not shown), a female internal housing 28, and the female internal stop surface 23.

[0043] The female external stop surface 21 and the male external stop surface 11 are arranged opposite each other so as to delimit a gap 30 between them. On the figure 1 , the gap 30 has an axial length of 0.43 mm.

[0044] The female outer abutment surface 21 extends radially between a first female outer radial end 29 and a first female inner radial end 26. The first female inner radial end 26 may be an edge break or a rounding having a radius of curvature between 0.1 mm and 5.0 mm and being directly adjacent to the female outer abutment surface 21.

[0045] The female internal abutment surface 23 is arranged facing the male internal abutment surface 13 and at a distance therefrom, for example at an axial distance of between 2 mm and 15 mm. The female internal abutment surface 23 extends from a second female internal radial end 27 to the female internal housing 28. The female internal abutment surface 23 may be straight or rounded so as to form a fillet. On the figure 1, the female internal stop surface 23 forms a fillet which has a radius of curvature whose value can for example be between 0.2 mm and 6.0 mm, preferably between 0.5 mm and 1.5 mm.

[0046] The female lip 24 has an inner surface 31 facing the male outer housing 14. The inner surface 31 is an unthreaded surface and has a cylindrical shape. The inner surface 31 extends from the first female inner radial end 26 to a distal thread flank 32 of the female threaded portion 22.

[0047] The female threaded portion 22 has a taper substantially equal to that of the male threaded portion 12. The female threaded portion 22 is arranged on the inside of the female element 25 and extends from the female internal housing 28 to the distal thread flank 32. The thread (not shown) of the threaded portion 22 has a variable width thread profile with self-locking tightening, such as a “wedge” type thread in English.

[0048] The female internal housing 28 is directly adjacent to the fillet formed by the female internal abutment surface 27 and extends to the female threaded portion 22. The female internal housing 28 has an unthreaded surface which may have a cylindrical or frustoconical shape. On the figure 1 , the female internal housing 28 has a cylindrical non-threaded surface.

[0049] A first axial length BSL extends and is measured axially between the first female inner radial end 26 and the second female inner radial end 27, so the distance between the points projected radially on the x axis is taken. The first axial length BSL can be between 60 mm and 300 mm, preferably between 100 mm and 250 mm, and even more preferably between 110 mm and 225 mm. On the figure 1 , the first axial length BSL is 217 mm.

[0050] A second axial length PSL extends and is measured axially between the first male inner radial end 18 and the second male inner radial end 19, so the distance between the points projected radially on the x axis is taken. The first axial length PSL can be between 60 mm and 300 mm, preferably between 100 mm and 250 mm, and even more preferably between 110 m and 225 m. On the figure 1, the second axial length PSL is 208mm.

[0051] There figure 2 illustrates a close-up view of detail A of the threaded joint shown schematically in figure 1 .

[0052] The gap 30 is delimited by the male external abutment surface 11 and the female external abutment surface 21. The male external abutment surface 11 and the female external abutment surface 21 are parallel. According to the embodiment illustrated in figure 2 which corresponds to that of the figure 1, the male external abutment surface 11 and the female external abutment surface 21 are orthogonal to the longitudinal axis x of the threaded joint 1. In other words, according to this embodiment, the male external abutment surface 11 forms with the y axis an angle α which is a flat angle or a zero angle. In the same way, the female external abutment surface 21 forms with the y axis an angle β which is a flat angle or a zero angle. The axes y and y are both orthogonal to the longitudinal axis x. The gap 30 thus formed between the male external abutment surface 11 and the female external abutment surface 21 has an axial length which can be between 0.10 mm and 1.75 mm. In the embodiment illustrated in figure 2 , the gap 30 has an axial length of 0.43 mm.

[0053] There figure 3 illustrates a close-up view of a variant of detail A shown in figure 2. According to this variant, the male external abutment surface 11 is inclined at an angle α relative to the y-axis, and the female external abutment surface 21 is inclined at an angle β relative to the y-axis. The y and y-axes are both orthogonal to the longitudinal axis x. The angle α may have a value between 0.1° and 30°, preferably between 0.1° and 10°, even more preferably between 0.1° and 5°. The angle β may have a value between 0.1° and 30°, preferably between 0.1° and 10°, even more preferably between 0.1° and 5°. In the embodiment of the figure 3 , the angle α and the angle β both have a value of 15°. The gap 30 thus formed between the male external abutment surface 11 and the female external abutment surface 21 has an axial length which can be between 0.10 mm and 1.75 mm. In the embodiment illustrated in figure 3 , the gap 30 has an axial length of 0.43 mm.

Claims

1. Threaded joint (1) having a longitudinal axis (x), said joint comprising a first tubular component (C1) and a second tubular component (C2), the first tubular component (C1) and the second tubular component (C2) being screwed to one another, - the first component (C1) comprising a first tube (10) and a male element (15) disposed at one end of said first tube (10), the male element (15) comprising successively from the first tube (10) to a male internal stop surface (13) of said male element: a male external stop surface (11), at least a first male threaded portion (12) having a self-locking variable-width thread profile, and the male internal stop surface (13), - the second component (C2) comprising a second tube (20) and a female element (25) disposed at one end of said second tube (20), the female element (25) comprising successively from the second tube (20) to a female external stop surface (21) of said female element: a female internal stop surface (23), at least a first female threaded portion (22) having a self-locking variable-width thread profile, a female lip (24) and the female external stop surface (21), a first axial length BSL between the female internal stop surface (23) and the female external stop surface (21) being greater than a second axial length PSL between the male internal stop surface (13) and the male external stop surface (11), the first axial length BSL and the second axial length PSL being such that an interstice (30) is formed between the male external stop surface (11) and the female external stop surface (21), said interstice (30) being closable by contact between the male external stop surface (11) and the female external stop surface (21) when an axial compressive load is applied.

2. Tubular joint (1) according to Claim 1, characterized in that the male external stop surface (11) is inclined by an angle α in relation to a first axis (y), said first axis (y) being perpendicular to the longitudinal axis (x), and in that the female external stop surface (21) is inclined by an angle β in relation to a second axis (y"), said second axis y" being perpendicular to the longitudinal axis (x), the angles α and β being such that the male external stop surface (11) and the female external stop surface (21) are substantially parallel.

3. Tubular joint (1) according to Claim 2, characterized in that the angles α and β are such that: 0°≤ α ≤30° and 0°≤ β ≤30°.

4. Tubular joint (1) according to Claim 2, characterized in that the angles α and β are such that: 0°≤ α ≤10° and 0°≤ β ≤10°.

5. Tubular joint (1) according to Claim 2, characterized in that the angles α and β are such that: 0°≤ α ≤5° and 0°≤ β ≤5°.

6. Tubular joint (1) according to Claim 2, characterized in that the angles α and β are both 0°.

7. Tubular joint (1) according to any one of the preceding claims, characterized in that the interstice (30) has an axial length of between 0.10 mm and 0.82 mm.

8. Tubular joint (1) according to any one of the preceding claims, characterized in that the interstice (30) has an axial length such that: BSL × 0 , 5 % 4 ≤ interstice 30 ≤ BSL × 0 , 7 % where BSL is in mm.