Threaded connection with anti-screw device

Description

Technical field

[0001] The present invention relates to an assembly for producing a threaded joint intended for use in a steel catenary, in particular subjected to torsional forces when arranged on a seabed to connect a wellhead at the seabed to surface equipment, or in a so-called OCTG column. Technological background

[0002] 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

[0003] In the state of the art, it is known to weld tubes end to end to produce a column intended to withstand such torsional forces. Alternatively, it is also known to produce such columns in 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 unscrewing of the formed joint, even when it is subjected to swell and sea currents.

[0004] The present invention is also useful for the implementation of columns intended for drilling or for preparing the exploitation of hydrocarbon wells ("drilling" and "drilling with casing"). The term "component used for drilling and exploitation of hydrocarbon wells" means any element of substantially tubular shape intended to be assembled with another element of the same type or not to ultimately constitute either a fitting capable of drilling a hydrocarbon well, or a casing or production column involved in the exploitation of the well, this column also being able to be used for drilling.

[0005] A threaded joint comprises a first and a second tubular steel component, the first tubular component comprising at one of its axial ends a male threaded zone produced on its outer circumferential surface, the second tubular component comprising at one of its axial ends a female threaded zone produced on its inner circumferential surface, the threaded joint being obtained by screwing to a final assembly position of the male threaded zone with the female threaded zone.

[0006] Components used for drilling or hydrocarbon well development applications are screwed together with a high tightening torque. This high torque is generally achieved through the tightening cooperation of stop surfaces provided on each of the components or by means of so-called self-locking threads. However, certain applications induce even higher stresses such as subsea risers. Therefore, high tightening torques must be used to prevent loosening between the components. However, the tightening torques are limited by the risk of plasticization of the steel surfaces brought into cooperation by tightening. It is therefore necessary to adapt the joints to the risk of untimely loosening.

[0007] Developments have been made to overcome these drawbacks. Thus, document US5794985 proposes a joint with a sleeve in which the ends of the male components are fitted into each other, inside the sleeve, so as to prevent rotation, and consequently, the unscrewing of the components independently of each other. However, if this arrangement indeed makes unscrewing (breakout) difficult, it also complicates the screwing of the male components into the sleeve. Indeed, it is necessary to position the male components relative to each other so that their ends can be fitted together at the end of screwing, which requires excessively precise control of the angular positions.

[0008] Also known from document US-5785357 is a threaded joint that does not require the two male components to be fitted together, but requires the fitting of a toothed ring carried by the male component, each tooth of the ring having to be received in a complementary toothing presented by the sleeve provided with the female thread. Such a ring is immobilized in rotation around the male element by splines cooperating with grooves in the male component. Such a design makes the assembly operation complicated because the end of screwing between the male component and the female component is dependent on the position of the toothed crown. However, the screwing keys 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 toothing. Finally, document US2013076028 proposes a threaded joint with an external sleeve.

[0009] The invention relates to a threaded joint which is simple to implement on site, both when screwing and unscrewing, and which offers significant resistance to unscrewing.

[0010] The solution of the invention provides a structural decorrelation of the means allowing the rotational immobilization of the ring around the male component, means allowing the unscrewing between the male component and the female component to be prevented.

[0011] The joint according to the invention is provided with an "anti-unscrewing" function. An "anti-unscrewing" function is understood to mean the ability of the joint not to unscrew unexpectedly, i.e. when this is not desired. More specifically, a joint provided with such a function must not unscrew when it is subjected in operation, for example, to torsional or tensile stresses, or even vibrations.

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

[0013] An idea at the basis 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 manner 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, a female end having a female thread and a female free end, said female end further comprising at least one extension extending axially from the side of the female thread and forming the female free end, said at least one extension being radially flexible and comprising on an inner surface an extension shoulder arranged to cooperate with a radial shoulder of a locking surface extending from an outer surface of the male end and axially limit in one direction the relative movement of the male end with respect to the female end. This makes it possible to increase the resistance of the joint to tensile, torsional or bending stresses against unscrewing.

[0015] According to embodiments, such a device may comprise one or more of the following features.

[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] According to one embodiment, the locking surface may be located on the side of the male thread opposite the free male end. Thus, the joint may be assembled by screwing according to standard practices of the trade.

[0018] According to one embodiment, a retaining ring may extend at least partially around the at least one extension. Thus, the anti-unscrewing performance is further improved.

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

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

[0021] According to one embodiment, the retaining ring may comprise a portion axially located 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 comprising the 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: BOSHmin > 0.2 × 2 × Ys × CL 2 3 × E × CH where E is the Young's modulus of the steel of extension 6 and Ys is the elastic limit of extension 6.

[0023] According to one embodiment, the locking surface (11) may have a maximum locking surface height BOSHmax such that BOSHmax ≤ 1.8 × 2 × Ys × CL 2 3 × E × CH where E is the Young's modulus of the steel of extension 6 and Ys is the elastic limit of 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 makes it possible to have resistance of the ring to extension stresses during stresses on the joint in tension, torsion or bending.

[0026] According to one embodiment, the locking surface may comprise an engagement surface having an angle of between 3° and 30°, preferably between 5° and 20°. This makes it easier to assemble the threaded joint.

[0027] According to one embodiment, the radial shoulder (18) may be a frustoconical surface with an angle greater than 0° and less than 30°, preferably with an angle of at least 3°. This makes it possible to improve 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 thread 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 greater than the upstream outer diameter CD, the retaining ring 14 having an annular inner diameter AD smaller than the end outer diameter CD and greater than the downstream outer diameter ED. This makes it possible to mount the retaining ring on the female end and to manipulate the female end with the ring, and in a second step to lock the retaining ring on the upstream portion of the extensions and to activate the anti-unscrewing function of the invention easily after assembly of the joint.

[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 seal is subjected to tensile, torsional or bending stresses. Brief description of the figures

[0030] 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. [ Fig. 1 ] There figure 1is a perspective view of a joint resulting from the screwed assembly of a set of tubular components according to the invention. Fig.2 ] There figure 2 is a sectional view of the joint of the figure 1 [ Fig.3 ] There figure 3 is a sectional and perspective view of a variation of the embodiment of the figure 1 [ Fig.4 ] There figure 4 is a sectional view of a seal according to one embodiment of the invention [ Fig.5 ] There Figure 5 is a sectional view of a seal according to an embodiment of the invention in a first position [ Fig.6 ] There figure 6 is a sectional view of a joint according to the embodiment of the Figure 5 in a second position. Description of the embodiments

[0031] Oil, gas, and other exploration requires a large number of pipes. Due to the many constraints these pipes undergo during both installation and operation, they must meet standards to prevent deterioration and leakage into the environment.

[0032] There 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 set includes as shown in the figure 1 a first tubular component with an axis of revolution X and provided at one of its ends with a male end 2 having a male thread 4 (visible in figure 2) made on the outer circumferential surface of said male end 2. Circumferential surface means the surface which extends longitudinally and over the entire circumference of the tubular component. On the other hand, surfaces which extend radially at the free edges of the tubular component are not considered to be circumferential surfaces.

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

[0035] The term "terminal surface" means the surface which extends at the free edge of the end 2 of the component over the thickness of the latter. In other words, the distal surface is in the form of an annular surface oriented generally radially relative to the X axis of the joint.

[0036] The male end 2 further comprises 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 of between 0° and 30° measured in a radial section containing the axis X and the angle being measured relative to a direction perpendicular to the axis X, i.e. a radial direction. When the angle B is strictly greater than zero degrees, the radial shoulder 18 is a frustoconical surface, the apex of which is located on the side of the free male end 13. The locking surface of the figure 1 is circumferentially continuous. Alternatively, the locking surface 11 may be circumferentially discontinuous. Preferably, the angle B of the radial shoulder 18 may be 1° minimum, more preferably 3° minimum and more preferably at most 15°.

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

[0038] More generally, the radial shoulder 18 of the locking surface 11 is arranged to oppose relatively the axial displacement, towards the free male end 13, of an object provided with 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 set also includes, as shown in the figure 1, a second tubular component with the same axis of revolution X and provided at one of its ends with a female end 3 having a female thread 5 made on the inner circumferential surface of said female end 3. Said female end 3 ends with a terminal surface or free female end 8.

[0041] The female end 3 comprises a plurality of extensions 6 distributed circumferentially and separated by recesses 7. The extensions 6 extend axially from the side of the female thread 5 and towards the female free end 8. The extensions 6 comprise the female free end 8. The extensions 6 have 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, in particular 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 comprises an extension shoulder 10 arranged to cooperate with the locking surface 11 and so as to prevent axial movement of the extension 6 relative to the male end 2 in the direction of movement of the extension 6 towards the free male end 3. On the figure 1 , the extension shoulder 10 is a frustoconical surface with an angle substantially corresponding to the angle of the radial shoulder 18 of the locking surface 11. The extension shoulder 10 extends radially from an inner 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 therefore 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 Figure 2 and 3comprises an engagement surface 15 arranged to allow the extensions 6 to slide on the locking surface 11 during assembly of the joint. 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 smaller diameter is located on the side of the free male end 13. The angle of the engagement surface 15 is between 3° and 30°, measured in a section plane and relative 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 axial size of the surface and additional resistance to assembly of the joint.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 the screwing of the female thread into the male thread, the extensions 6 slide by rubbing on 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 3 mm.

[0046] The locking surface 11 can be obtained by machining the outer surface of the male threaded end 2, or by adding a metal ring that is shrunk, glued or welded onto the outer surface of the male threaded end.

[0047] The extensions 6 comprise an extension engagement surface 19 corresponding to the engagement surface 15, i.e. having a frustoconical 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 comprise an extension shoulder 10 opposing the unscrewing of the male end of the female end, each extension shoulder 10 bearing on the locking surface 11, more precisely each extension shoulder 10 bearing on the radial shoulder 18 of the locking surface 11, which makes it possible to obtain a joint which withstands higher levels of torsional or bending stresses without undergoing untimely unscrewing, while maintaining ease of assembly on site since it is sufficient to screw the ends together in a manner similar to usual practices.

[0049] The threaded joint of the figures 1 to 3further comprises 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 outside the extensions 6. With a retaining ring, the joint according to the invention withstands higher levels of torsional or bending stresses without undergoing unscrewing. The anti-unscrewing performance is thus improved with a modification of the practices of assembly of joints on site which remains minimal compared to the solutions of the state of the art.

[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 less than an outer diameter of the extensions 6 by at least 0.4 mm. This second portion 21 makes it possible to protect 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 visible on the 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. 1 to 8 screws can thus be screwed into 1 to 8 corresponding extensions 6. From 4 to 12 screws 22 are generally sufficient when the joint comprises at least 4 extensions 6 distributed circumferentially.

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

[0054] Alternatively, the retaining ring can be a clamp, for example from Jubilee or CFInox.

[0055] According to one aspect, 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: BOSHmin > 0.2 × 2 × Ys × CL 2 3 × E × CH where E is the Young's modulus of the steel of extension 6 and Ys is the elastic limit of extension 6.

[0056] Also, the locking surface 11 has a maximum locking surface height BOSHmax such that BOSHmax ≤ 1.8 × 2 × Ys × CL 2 3 × E × CH

[0057] The extension length CL is understood as the axial dimension of the extension 6 on its free part, that is to say 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 a male end outer diameter, measured at an axial distance of at most 10 mm from the locking surface 11.

[0058] The extension height CH is understood as the radial dimension of the extension 6 at its free portion. The extension height CH 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 external diameter of 177.8 mm (7 inches) extensions 6 were made with a CL extension length of 80 mm.

[0060] In another variant represented in Figures 5 and 6 , the extensions 6 comprise three successive portions: an upstream portion 25 located on the side of the female thread 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 greater than the upstream diameter CD. The retaining ring 14 has an annular inner diameter AD smaller than the end outer diameter CD and greater than the downstream outer diameter ED.

[0061] The extension shoulder 18 has an extension shoulder inner diameter IEPD, the extension 6 has on the downstream portion 24 a downstream inner diameter IED. The annular inner diameter AD and the downstream outer diameter are such that: 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, that is to say that these two diameters are in tight fit or with a clearance, for example a clearance between -0.1 mm and + 1 mm.

[0063] In this variant, the retaining ring 14 is placed on the extensions 6, is retained by the end portion 23. When the retaining ring 14 is at the downstream portion 24, the assembly of the female end 3 on the male end 2 is possible because the retaining ring does not block the radial movement of the extensions 6 during assembly. When the retaining ring 14 is positioned at the upstream portion 25, the retaining ring opposes the radial separation of the extensions 6, thus preventing the unscrewing of the joint thus formed. 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 in such a way that the male end is at the bottom and the female end is at the top, the retaining ring 14 can slide and be held in position by gravity on the upstream portion 25. Finally, it is possible to combine this variant with other fixing means presented in other variants, such as screws, glue. Also, the ring can advantageously be made of steel or an alloy comprising bronze.

[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 makes it possible to limit the axial movement of the ends relative to each other and, in synergy with the threads, to limit the possibility of sliding of the male and female sealing surfaces relative to each other. Thus, the invention makes it possible to improve 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 joint and a joint of the same model modified to incorporate an embodiment according to the invention. This joint according to the invention comprises 36 extensions 6 distributed circumferentially over 360° and does not comprise a retaining ring. Both joints were subjected to a torsion test. The joint according to the invention achieved an improved torsional strength of 80%, the joint according to the invention without extension makes it possible to provide a torsional strength representing 16% of the torsional strength of the tube (100% corresponding to the strength of the tube on which the male end or the female end is made). Simulations have shown that a joint further comprising a retaining ring makes it possible to achieve strength values ​​of the order of 40 to 50% minimum of the torsional strength of the tube.

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

Claims

1. Threaded joint (1) comprising a male end (2) having a male thread (4) and a free male end (13), a female end (3) having a female thread (5) and a free female end (8), said female end (3) also comprising at least one extension (6) extending axially from the side of the female thread (5) and forming the free female end (8), the threaded joint being characterized in that said at least one extension (6) is flexible radially and comprises 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 to limit axially in one direction the relative movement of the male end (2) relative to the female end (3).

2. Threaded joint (1) according to 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 limit axially in one direction the relative movement of the male end (2) relative to the female end (3).

3. Threaded joint (1) according to Claim 1 or 2, wherein the locking surface (11) is located on the side of the male thread (4) opposing the free male end (13).

4. Threaded joint (1) according to one of Claims 1 to 3, also comprising a retaining ring (14) extending at least partially about the at least one extension (6).

5. Threaded joint (1) according to Claim 4, wherein the retaining ring is fixed to the extensions (6) by a means selected from screws, adhesive or pins.

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

7. Threaded joint (1) according to either of Claims 4 and 5, wherein the retaining ring (14) comprises a portion (21) axially located beyond the extensions (6) and extending radially toward the external surface (12) of the male end, said portion (21) being arranged to protect said extensions (6).

8. Threaded joint (1) according to one of Claims 1 to 7, wherein the extensions (6) have individually an extension length CL and an extension height CH, and the locking surface (11) has a minimum locking surface height BOSHmin (in mm) such that : BOSHmin > 0.2 × 2 × Ys × CL 2 3 × E × CH where E is the Young's modulus of the steel of the extension 6 and Ys is the elastic limit of the extension 6.

9. Threaded joint (1) according to Claim 7, wherein the locking surface (11) has a maximum locking surface height BOSHmax such that BOSHmax ≤ 1.8 × 2 × Ys × CL 2 3 × E × CH where E is the Young's modulus of the steel of the extension 6 and Ys is the elastic limit of the extension 6.

10. Threaded joint (1) according to one of Claims 4 to 9, wherein the retaining ring (14) has a height RH of the retaining ring (14) of at least 0.5 mm.

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

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

13. Threaded joint (1) according to 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 external diameter CD, a downstream portion 24 having a downstream external diameter ED which is less than the upstream external diameter CD, an end portion 23 on the side of the free female end (8), the end portion 23 having an end external diameter BD which is greater than the upstream external diameter CD, the retaining ring 14 having an annular internal diameter AD which is less than the end external diameter CD and greater than the downstream external diameter ED.

14. Threaded joint (1) according to 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 in order to form a seal.