Threaded joint with unscrewing prevention device

Abstract

The invention relates to a threaded joint (1) comprising a male end (2) having a male thread (4) and a male free end (13), a female end (3) having a female thread (5) and a female free end (8), the female end (3) further comprising at least one extension (6) extending axially from the side of the female thread (5) and forming the female free end (8), the at least one extension (6) being radially flexible and comprising, on an inner surface (9), an extension shoulder (10) arranged so as to engage with a locking surface (11) extending from an outer surface (12) of the male end (2) and axially limit the relative movement of the male end (2) relative to the female end (3) in one direction.

Description

Description Threaded joint with anti-loosening device technical field [1]The present invention relates to an assembly for making a threaded joint intended for use in a steel catenary, in particular subjected to torsional forces when placed on a seabed to connect a wellhead on the seabed to equipment on the surface, or in a column called OCTG. Technological background [2]Metal tubes are widely used in various fields of the energy industry such as power generation, oil and gas, as well as in mechanical engineering. Summary [3] In the prior art, it is known to weld tubes end to end to create a column designed to withstand such torsional forces. Alternatively, it is also known to make such columns from flexible materials. The object of the invention is to provide an alternative to known techniques based on a threaded joint comprising means for limiting the loosening of the joint formed, even when subjected to swell and ocean currents. [4] The present invention is also useful for the implementation of columns intended for drilling or for preparing hydrocarbon wells for production ("drilling" and "drilling with casing"). A component "used for drilling and producing hydrocarbon wells" means any substantially tubular element intended to be assembled with another element of the same or different type to ultimately form either a packing suitable for drilling a hydrocarbon well, or a casing or production column used in well production, this column also being able to be used for drilling. [5] A threaded joint comprises a first and a second tubular steel component, the first tubular component having at one of its ends axial a male threaded zone made on its outer circumferential surface, the second tubular component having at one of its axial ends a female threaded zone made on its inner circumferential surface, the threaded joint being obtained by screwing until a final assembly position of the male threaded zone with the female threaded zone. [6] Components used in hydrocarbon drilling or well production applications are screwed together with high tightening torque. This high torque is generally achieved through the cooperation of thrust surfaces on each component or by means of so-called self-locking threads. However, some applications induce even higher stresses, such as subsea risers. "Risers." Therefore, high tightening torques must be used to prevent loosening between components. However, tightening torques are limited by the risk of plastic deformation of the steel surfaces joined by tightening. It is therefore necessary to adapt the seals to mitigate the risk of unexpected loosening. [7] Developments have been made to overcome these drawbacks. For example, US patent 5794985 proposes a sleeve joint in which the ends of the male components are fitted one inside the other within the sleeve, so as to prevent rotation and, consequently, the unscrewing of the components independently of each other. However, while this arrangement does indeed make unscrewing (breakout) difficult, it also complicates the screwing of the male components into the sleeve. This is because it is necessary to position the male components relative to each other so that their ends fit together at the end of the screwing process, which requires extremely precise control of the angular positions. [8] Also known from US-5785357 is a threaded joint that does not require the two male components to be fitted together, but requires a toothed ring carried by the male component to be fitted together. Each tooth of the ring must be received in a complementary serration on the sleeve with the female thread. Such a ring is prevented from rotating around the male element by splines that cooperate with grooves in the male component. This design complicates the assembly operation because the final tightening of the screw between the male and female components depends on the position of the toothed crown. However, the screw wrenches used on site have tolerances, and it is very complicated to guarantee the alignment of the numerous teeth carried by the ring in their complementary serrations. [9]The invention relates to a threaded joint which is simple to implement on site, both for screwing and unscrewing, and which offers significant resistance to unscrewing.

[0010] The solution of the invention provides for a structural decorrelation of the means enabling the rotational immobilization of the ring around the male component, and of the means enabling the prevention of unscrewing between the male component and the female component. [1 l] The seal according to the invention is equipped with an "anti-loosening" function. The "anti-loosening" function refers to the seal's ability to prevent it from unscrewing unintentionally, that is, when this is not desired. More specifically, a seal equipped with such a function must not unscrew when subjected, for example, to torsional or tensile stresses, or vibrations, during operation.

[0012] The anti-loosening function of a seal according to the invention is linked to the fact that it is not possible to separate the first tubular component from the second by applying a torsional torque between the two components.

[0013] One idea at the heart of the invention is to prevent the unscrewing of the two components by limiting the possibility of unscrewing, which by a helical movement combines rotational and translational movements, by blocking the axial translation of the two ends, while not preventing the assembly of the two components in a conventional way by screwing.

[0014] According to one embodiment, the invention provides a threaded joint comprising a male end having a male thread and a male free end, and a female end having a female thread and a female free end. The female end further comprises at least one extension extending axially from the side of the female thread and forming the female free end. This at least one extension is radially flexible and comprises, on an internal surface, an extension shoulder arranged to cooperate with a radial shoulder of a locking surface extending from an external surface of the male end and axially limiting, in one direction, the relative movement of the male end with respect to the female end. This increases the resistance of the joint to tensile, torsional or flexural stresses against unscrewing.

[0015] According to some embodiments, such a device may include one or more of the following characteristics.

[0016] According to one embodiment, the female end may comprise a plurality of extensions separated by recesses and distributed circumferentially, each extension being radially flexible and comprising on its internal surface an extension shoulder arranged to cooperate with the radial shoulder of the locking surface and axially limit in one direction the relative movement of the male end with respect to the female end.

[0017] In one embodiment, the locking surface can be located on the side of the male thread opposite the free male end. Thus, the seal can be assembled by screwing according to standard industry practices.

[0018] In one embodiment, a retaining ring can extend at least partially around at least one extension. This further improves the anti-loosening performance.

[0019] In one embodiment, the retaining ring can be fixed to the extensions by means chosen from screws, glue, or pins. Thus, the retaining ring is held in position during the use of the joint.

[0020] According to one embodiment, the retaining ring can be a hose clamp.

[0021] In one embodiment, the retaining ring may include a portion located axially beyond the extensions and extending radially towards the outer surface of the male end, said portion being arranged to protect said extensions. Thus, the extensions and their functional surfaces are protected, in particular during the transport or handling of tubes having a female end.

[0022] According to one embodiment, the extensions (6) may individually have an extension length CL, an extension height CH, and the locking surface (11) has a minimum locking surface height BOSHmin (in mm) such that: [ L Math II JBOSHmin > 0.2 where E is the Young's modulus of the steel at extension 6 and Ys is the elastic limit at extension 6.

[0023] According to one embodiment, the locking surface (11) may have a maximum locking surface height BOSHmax such that [ L Math 2] J BOSHmax < 1.8 where E is the Young's modulus of the steel at extension 6 and Ys is the elastic limit at extension 6.

[0024] Thus, the anti-unscrewing performance is improved.

[0025] According to one embodiment, the retaining ring may have a retaining ring height RH of at least 0.5 mm. This ensures the ring's resistance to extensional stresses when the joint is subjected to tension, torsion, or bending.

[0026] According to one embodiment, the locking surface may include an engagement surface having an angle between 3° and 30°, preferably between 5° and 20°. This facilitates the assembly of the fused seal.

[0027] According to one embodiment, the radial shoulder (18) can be a frustoconical surface with an angle greater than 0° and less than 30°, preferably with an angle of at least 3°. This improves anti-unscrewing performance.

[0028] According to one embodiment, the extensions 6 may comprise three successive portions: an upstream portion 25 located on the side of the female end 5 and having an upstream outer diameter CD, a downstream portion 24 having a downstream outer diameter ED smaller than the upstream outer diameter CD, an end portion 23 with an end outer diameter BD larger than the upstream outer diameter CD, and the retaining ring 14 having an annular inner diameter AD smaller than the end outer diameter CD and larger than the downstream outer diameter ED. This allows the retaining ring to be mounted on the female end and the female end to be manipulated with the ring, and subsequently, the retaining ring to be locked onto the upstream portion of the extensions and the anti-unscrewing function of the invention to be easily activated after assembly of the seal.

[0029] According to one embodiment, the male end 2 may comprise a male sealing surface 26 and the female end 3 may comprise a female sealing surface 27, the male sealing surface 26 being arranged to cooperate with the female sealing surface 27 to form a seal. Thus, a seal according to the invention makes it possible to maintain or improve sealing performance when the joint is subjected to tensile, torsional or bending stresses. Brief description of the figures

[0030] The invention will be better understood, and other objects, details, features, and advantages thereof will become more apparent from the following description of several particular embodiments of the invention, given solely by way of illustration and not limitation, with reference to the accompanying drawings. [Fig. 1] Figure 1 is a perspective view of a joint resulting from the screw assembly of a set of tubular components according to the invention. [Fig. 2] Figure 2 is a cross-sectional view of the joint in Figure 1 [Fig. 3] Figure 3 is a cross-sectional and perspective view of a variation of the embodiment of Figure 1 [Fig. 4] Figure 4 is a cross-sectional view of a joint according to one embodiment of the invention [Fig. 5] Figure 5 is a cross-sectional view of a joint according to an embodiment of the invention in a first position [Fig.6] Figure 6 is a cross-sectional view of a joint according to the embodiment of Figure 5 in a second position. Description of the implementation methods

[0031] Oil, gas, and other resource extraction processes require a significant number of pipes. Due to the numerous stresses these pipes undergo during both installation and operation, they must adhere to specific standards to prevent degradation and leaks into the environment.

[0032] Figure 1 represents a threaded joint resulting from the assembly of a set of tubular components, this joint having an axis of revolution X.

[0033] This assembly, as shown in Figure 1, comprises a first tubular component with axis of revolution X and having at one of its ends a male end 2 having a male thread 4 (visible in Figure 2) formed on the outer circumferential surface of said male end 2. The circumferential surface is understood to be the surface extending longitudinally and over the entire circumference of the tubular component. On the other hand, surfaces that extend radially at the free edges of the tubular component are not considered circumferential surfaces.

[0034] The thread can be continuous, interrupted, multiple, simple, regular, irregular, etc... The end 1 terminates with a terminal surface or male free end 13.

[0035] The terminal surface is defined as the surface extending from the free edge of end 2 of the component over its thickness. In other words, the distal surface is an annular surface oriented generally radially with respect to the X-axis of the joint.

[0036] The male end 2 further includes on its outer circumferential surface a locking surface 11 comprising a radial shoulder 18. The radial shoulder 18 is a surface having an angle B between 0° and 30° measured in a radial section containing the X axis and the angle being measured with respect to a direction perpendicular to the X axis, i.e. a radial direction. When angle B is strictly greater than zero degrees, the radial shoulder 18 is a frustoconical surface, the apex of which lies on the side of the male free end 13. The locking surface of Figure 1 is circumferentially continuous. Alternatively, the locking surface 11 may be circumferentially discontinuous. Preferably, angle B of the radial shoulder 18 may be a minimum of 1°, more preferably a minimum of 3°, and more preferably still a maximum of 15°.

[0037] The radial shoulder 18 may not be a frustoconical surface but a curved surface, presenting a tangent on an outer part radially and greater than 90°.

[0038] More generally, the radial shoulder 18 of the locking surface 11 is arranged to oppose, relative to the axial displacement, towards the male free end 13, of an object having a corresponding surface.

[0039] The locking surface 11 is located on the opposite side to the free male end 13 with respect to the male thread 4, and is located at a predetermined non-zero distance from said male thread 4. Said predetermined distance is at least 15mm.

[0040] This assembly also includes, as shown in Figure 1, a second tubular component with the same axis of revolution X and having at one of its ends a female end 3 having a female thread 5 made on the inner circumferential surface of said female end 3. Said female end 3 terminates with a terminal surface or free female end 8.

[0041] The female end 3 comprises a plurality of circumferentially distributed extensions 6 separated by recesses 7. The extensions 6 extend axially from the side of the female thread 5 towards the free female end 8. The extensions 6 include the free female end 8. The extensions 6 exhibit radial flexibility such that an extension terminal end 17 can have a first position without radial stress, and can have a second position further from the X-axis than the first position when the extension 6 is subjected to radial stress, particularly when the extension 6 is subjected to a contact force between the extension 6 and the locking surface 11, in particular the contact force between an engagement surface 15 and an extension engagement surface 19.

[0042] An extension 6 includes an extension shoulder 10 arranged to cooperate with the locking surface 11 and to prevent axial movement of the extension 6 relative to the male end 2 in the direction of a displacement of the extension 6 towards the free male end 3. In Figure 1, the extension shoulder 10 is a frustoconical surface with an angle corresponding substantially to the angle of the radial shoulder 18 of the locking surface 11. The extension shoulder 10 extends radially from an internal surface 9 of the extension 6 and inwards.

[0043] Alternatively, the female end may have only one extension 6.

[0044] Alternatively, the female end may comprise 4 extensions 6 arranged circumferentially at 90° and thus distributed over 360°, or the female end may comprise 4 extensions 6 distributed over 90°, or the female end may comprise 36 extensions 6 distributed over 360°

[0045] The locking surface 11, visible in Figures 2 and 3, includes an engagement surface 15 arranged to allow the extensions 6 to slide on the locking surface 11 during joint assembly. The engagement surface 15 is oriented towards the free male end 13. The engagement surface 15 is located between the radial shoulder 18 and the free male end 13. The engagement surface 15 is a frustoconical surface whose smallest The diameter is located on the side of the male free end 13. The angle of the engagement surface 15 is between 3° and 30°, measured in a cutting plane and with respect to the axis of revolution X of the male end 2. Preferably, the angle of the engagement surface 15 is between 5° and 20°. This presents a good compromise between the axial size of the surface and additional strength to the joint assembly. When the female end 3 is screwed onto the male end 2, the extensions 6 follow a helical movement relative to the male end 2 imposed by screwing the female thread into the male thread. The extensions 6 slide, rubbing against the engagement surface 15 in this helical movement, the engagement surface 15 causing a radial separation of said extensions 6.The axial position of the locking surface 11 is such that at the end of screwing, the extension shoulder 10 of an extension 6 is located at least partially beyond the radial shoulder surface 18, either bearing on said radial shoulder 18, or with an axial clearance between the radial shoulder 18 and the extension shoulder 10. The axial clearance can be at most 3mm.

[0046] The locking surface 11 can be obtained by machining the outer surface of the male threaded end 2, or by adding a shrink-fitted metal ring, glued or welded to the outer surface of the male threaded end.

[0047] The extensions 6 include an engagement surface of extension 19 corresponding to the engagement surface 15, that is to say having a truncated conical shape with an angle substantially identical to the angle of the engagement surface 15.

[0048] The extension(s) 6 are located after the female thread on the female connection, and each includes an extension shoulder 10 opposing the unscrewing of the male end of the female end, each extension shoulder 10 bearing against the locking surface 11, more precisely each extension shoulder 10 bearing against the radial shoulder 18 of the locking surface 11, which makes it possible to obtain a joint which supports higher levels of torsional or bending stresses without suffering from unintentional unscrewing, while maintaining ease of assembly on site since it is enough to screw the ends together in a manner similar to usual practices.

[0049] The threaded joint shown in Figures 1 to 3 further includes a retaining ring 14 arranged to prevent radial separation of the extensions 6. The retaining ring 14 is a separate element from the male end 2 and the female end 3. The retaining ring comprises a first portion 20 extending axially at the level of the extensions 6, and radially outward from the extensions 6. With a retaining ring, the joint according to the invention withstands higher levels of torsional or bending stress without loosening. The anti-loosening performance is thus improved with minimal modification to joint assembly practices on site compared to prior art solutions.

[0050] In a variant shown in Figure 3, the retaining ring 14 comprises a second portion 21 extending axially beyond the extensions 6 on the side opposite the thread of the female end 3, said second portion extending radially to an inner diameter of the second portion that is at least 0.4 mm smaller than an outer diameter of the extensions 6. This second portion 21 protects the extensions 6 during the transport of the tubular components or during the operation of the catenaries.

[0051] The retaining ring 14 has a radial thickness of at least 0.5 mm.

[0052] In a variation shown in Figure 1, the retaining ring 14 is held in position on the extensions 6 by screwing, with screws 22 screwed radially through an outer surface of the retaining ring and into threaded holes provided in several extensions. One to eight screws can thus be screwed into one to eight corresponding extensions 6. Four to twelve screws 22 are generally sufficient when the joint comprises at least four circumferentially distributed extensions 6.

[0053] According to one variant, the retaining ring can be glued onto the extensions, or fretted onto said extensions.

[0054] According to one variant, the retaining ring can be a hose clamp, for example from the company Jubilee or CFInox.

[0055] According to one aspect, the 6 extensions individually have an extension length CL, an extension height CH, and the locking surface li has a minimum locking surface height BOSHmin (in mm) such that: [ L Math 1] J BOSHmin > 0.2 where E is the Young's modulus of the steel at extension 6 and Ys is the elastic limit at extension 6.

[0056] Also, the locking surface 11 has a maximum locking surface height BOSHmax such that [ L Math 2] J BOSHmax < 1.8

[0057] The extension length CL is understood as the axial dimension of the extension 6 on its free part, i.e. at the level of the recesses 7, from one end of the recess 7 on the female thread side and up to the extension shoulder 10. The locking surface height BOSH is understood as the radial dimension of the locking surface 11, relative to an outside diameter of male end, measured at an axial distance of no more than 10mm from the locking surface 11.

[0058] The CH extension height is understood as the radial dimension of the extension 6 at its free portion. The CH extension height is generally between 2 mm and 10 mm.

[0059] The CL extension length is at least 15 mm. For example, with tube ends of nominal outside diameter of 177.8 mm (7 inches), 6 extensions were made with a CL extension length of 80 mm.

[0060] In another variant shown in Figures 5 and 6, the extensions 6 comprise three successive portions: an upstream portion 25 located on the female thread side and having an upstream outside diameter CD, a downstream portion 24 having a downstream outside diameter ED smaller than the upstream outside diameter CD, and an end portion 23 with an end outside diameter BD larger than the upstream diameter CD. The retaining ring 14 has an annular inner diameter AD smaller than the end outside diameter CD and larger than the downstream outside diameter ED.

[0061] The extension shoulder 18 has an internal diameter of the extension shoulder IEPD, and extension 6 has a downstream internal diameter IED on its portion 24. The annular internal diameter AD and the downstream external diameter are such that: [Math 3]AD - ED > BOSH - (IED - IEPD)

[0062] The retaining ring 14 has an axial length less than the axial length of the downstream portion 24. The annular inner diameter AD is close to the upstream outer diameter CD, i.e. these two diameters are in tight fit or with clearance, for example a clearance between -0.1mm and +1mm.

[0063] In this variant, the retaining ring 14 is positioned on the extensions 6 and held in place by the end portion 23. When the retaining ring 14 is at the level of the downstream portion 24, the assembly of the female end 3 onto the male end 2 is possible because the retaining ring does not impede the radial movement of the extensions 6 during assembly. When the retaining ring 14 is positioned at the level of the upstream portion 25, the retaining ring opposes the radial separation of the extensions 6, thus preventing the joint thus formed from unscrewing. The advantages of this variant are that the retaining ring is integrated into the female end, which facilitates handling on site.Also, since in most cases the tubular components inserted into a casing or catenary column are assembled with the male end at the bottom and the female end at the top, the retaining ring 14 can slide and be held in position by gravity on the upstream portion 25. Finally, this variant can be combined with other fastening methods presented in other variants, such as screws or adhesive. The ring can also advantageously be made of steel or a bronze alloy.

[0064] In all embodiments described below, the male end may include at least one male sealing surface arranged to cooperate with at least one female sealing surface on the female end to form a metallic seal.

[0065] Advantageously, the interaction between the extensions 6 and the locking surface 11 limits the axial movement of the ends relative to each other and, in synergy with the threads, limits the possibility of slippage between the male and female sealing surfaces. Thus, the invention improves the sealing performance of the joint formed under stress, particularly in tension, bending, or torsion.

[0066] A test was conducted comparing a state-of-the-art seal with a modified seal of the same design incorporating an embodiment according to the invention. This seal according to the invention comprises 36 extensions distributed circumferentially over 360° and does not include a retaining ring. Both seals were subjected to a torsion test. The seal according to the invention achieved an 80% improvement in torsional strength, while the seal according to the invention without extensions allows for to provide torsional resistance representing 16% of the tube's torsional strength (100% corresponding to the resistance of the tube on which the male or female end is formed). Simulations have shown that a joint also incorporating a retaining ring makes it possible to achieve resistance values ​​of at least 40 to 50% of the tube's torsional strength.

[0067] A seal according to the invention can therefore be assembled by screwing a male end into a female end. During the screwing step, the extensions 6 contact the locking surface 11, the engagement surface 15 radially pushing the ends of the extensions 6 outwards until the extension shoulders 10 reach an axial position where the extensions 6 return at least partially radially inwards and the extension shoulders are in a position bearing against the retaining surface 16 of the locking surface 11. Then, the retaining ring 14 is positioned axially at the level of the extensions 6, so as to prevent axial separation of the extensions 6. The retaining ring is then fixed onto the extensions 6, for example by screwing.Thus, the assembly operations of a threaded joint with anti-loosening properties are simplified, with only one additional element to assemble in addition to the two threaded ends.

Claims

Demands

1. Threaded joint (1) comprising a male end (2) having a male thread (4) and a male free end (13), a female end (3) having a female thread (5) and a female free end (8), said female end (3) further comprising at least one extension (6) extending axially from the side of the female thread (5) and forming the female free end (8), said at least one extension (6) being radially flexible and comprising on an internal surface (9) an extension shoulder (10) arranged to cooperate with a radial shoulder (18) of a locking surface (11) extending from an external surface (12) of the male end (2) and axially limiting in one direction the relative movement of the male end (2) with respect to the female end (3).

2. Threaded joint (1) of claim 1 wherein the female end (3) comprises a plurality of extensions (6) separated by recesses (7) and distributed circumferentially, each extension (6) being radially flexible and comprising on its internal surface (9) an extension shoulder (10) arranged to cooperate with the radial shoulder (18) of the locking surface (11) and to axially limit in one direction the relative movement of the male end (2) with respect to the female end (3).

3. Threaded joint (1) of claim 1 or 2 wherein the locking surface (11) is located on the side of the male thread (4) opposite the male free end (13).

4. Threaded joint (1) according to any one of claims 1 to 3 further comprising a retaining ring (14) extending at least partially around at least one extension (6).

5. Threaded joint (1) according to claim 4 in which the retaining ring is fixed on the extensions (6) by a means selected from screws, glue, pins.

6. Threaded joint (1) according to claim 4 wherein the retaining ring (14) is a clamping collar.

7. Threaded joint (1) according to any one of claims 4 to 5 in which the retaining ring (14) comprises a portion (21) axially situated beyond the extensions (6) and extending radially towards the outer surface (12) of the male end, said portion (21) being arranged to protect said extensions (6).

8. Threaded joint (1) according to any one of claims 1 to 7 wherein the extensions (6) individually have an extension length CL, an extension height CH, and the locking surface (11) has a minimum locking surface height BOSHmin (in mm) such that: [ L Math 1] J BOSHmin > 0.2 where E is the Young's modulus of the steel at extension 6 and Ys is the elastic limit at extension 6.

9. Threaded joint (1) according to claim 7 wherein the locking surface (11) has a maximum locking surface height BOSHmax such that [ L Math 2] J BOSHmax < 1.8 where E is the Young's modulus of the steel at extension 6 and Ys is the elastic limit at extension 6.

10. Threaded joint (1) according to any one of claims 4 to 9 in which the retaining ring (14) has a retaining ring height RH (14) of at least 0.5 mm.

11. Threaded joint (1) according to any one of claims 1 to 10 in which the locking surface (11) comprises an engagement surface (15) having an angle between 3° and 30°, preferably between 5° and 20°.

12. Threaded joint (1) according to any one of claims 1 to 11 wherein the radial shoulder (18) is a frustoconical surface with an angle greater than 0° and less than 30°, preferably a frustoconical surface with an angle of at least 3°.

13. Threaded joint (1) according to any one of claims 1 to 5 or 7 to 12 wherein the extensions 6 comprise three successive portions: an upstream portion 25 located on the side of the female thread 5 and having an upstream outside diameter CD, a downstream portion 24 having a downstream outside diameter ED less than the upstream outside diameter CD, an end portion 23 on the side of the female free end (8), the end portion 23 having an end outside diameter BD greater than the upstream outside diameter CD, the retaining ring 14 having an annular inner diameter AD less than the end outside diameter CD and greater than the downstream outside diameter ED.

14. Threaded joint (1) according to any one of claims 1 to 13 wherein the male end 2 comprises a male sealing surface 26 and the female end 3 comprises a female sealing surface 27 and the male sealing surface 26 is arranged to cooperate with the female sealing surface 27 to form a seal.

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