THREADED TUBULAR CONNECTION WHICH IS RESISTANT TO BENDING STRESSES

Description

[0001] The invention relates to a threaded tubular connection for a tubular string which is subjected to dynamic bending loads, comprising a male tubular element provided with a male threaded portion and a female tubular element provided with a female threaded portion.

[0002] That type of threaded connection is intended for making strings for hydrocarbon or the like wells.

[0003] In addition to relatively constant (static) axial tensile loads, under the action of waves, the wind, the tides and sea currents, strings connecting an offshore platform to the sea bed are subjected to variable (dynamic) bending loads. Said loads are transmitted from one tube to the next in the string through the threaded connections.

[0004] Figure 3 shows that the last threads of the male element and the female element are subjected to a maximum bending moment which has to be transmitted in addition to the whole of the axial tensile load.

[0005] This results in dynamic tensile loads known as repeated loads at the root of the last threads, and more particularly the last male threads, which initiates fatigue cracking at that location leading to catastrophic rupture of the string.

[0006] International patent applications WO-A-01/75345 and WO-A-01/75346 describe solutions for reducing stresses at the roots of said threads, but the resulting improvement may prove insufficient.

[0007] US 2002/0017788 discloses a threaded connection wherein the sealing zone on the box is undulated so that flexure in a corresponding zone of the pin end is reduced by provision of a support contact with the pin end external surface.

[0008] Said dynamic loads also cause friction between the parts of the male and female elements in contact, leading to cracking due to fretting fatigue.

[0009] When one of the tubular elements has an axial abutment surface at its free end which abuts against the other tubular element, the abutement that occurs enables to absorb part of the bending moment. However, to form such abutment surfaces, it is necessary to choose thicker tubes or to increase their thickness locally by upsetting, which introduces increased costs.

[0010] The aim of the invention is to owercome these disadvantages thanks to an appropriate distribution of bending loads and optionally of tensile loads.

[0011] The invention also aims to provide spaces to house lubricating grease and the debris resulting from wear of the surfaces in contact.

[0012] A further aim is to provide sealing surfaces between the threaded portions and the outside of the threaded connection which do not constitute a source of cracking due to fretting fatigue.

[0013] A final aim is to provide multiple sealing surfaces which enable to maintain a seal in the event of deterioration of certain thereof.

[0014] In particular, the invention provides a threaded connection of the type defined in the introduction, comprising at least one transfer zone axially disposed between said threaded portions and the free end of one of said tubular elements, it being axially spaced from said threaded portions in order to transfer a fraction of at least 20%, preferably at least 30% of the bending moment to which the connection is subjected from one element to the other, the male and female elements having respective transfer surfaces in mutual contact with a radial interference fit in said transfer zone, at least one of the transfer surfaces being an undulated surface defining a series of annular rounded ribs which come into interfering contact with the facing transfer surface, the maximum diameter point and the minimum diameter point of the undulation profile being located on respective rounded portions of the profile, wherein said transfer zone is axially disposed between said threaded portions and the free end of the female element.

[0015] Optional characteristics of the invention, which may be complementary or be by substitution, are given below:

• said free end of one of the tubular elements has a front surface which is free of contact with the other tubular element;
• the axial length of the transfer zone is selected so as to limit the contact pressure resulting from transferring the bending moment to a fraction of the yield strength of the material to less than 1 and preferably less than 0.5;
• said male and female transfer surfaces are lubricated;
• said facing transfer surface is a smooth surface;
• said undulated surface is not in contact with said smooth surface between said ribs;
• said two transfer surfaces are undulated surfaces;
• the ribs of one transfer surface are housed between the ribs of the facing transfer surface;
• said undulated surface or surfaces has/have a periodic profile;
• said periodic profile is asymmetric;
• said profile forms part of the male transfer surface and is defined by a first convex rounded portion containing a point with a maximum profile diameter, by a second concave rounded portion containing a point with a minimum profile diameter and which is tangential to the first rounded portion, and by a third convex rounded portion which is tangential to the first and second rounded portions and which has a radius which is substantially lager thereof;
• the second rounded portion has a larger radius than the first rounded portion;
• starting from the free end of the male element, the axial distance between a maximum profile diameter point and the following minimum diameter point of the profile is less than the axial distance between a minimum profile diameter point and the following maximum diameter point of the profile;
• the third profile is located between a minimum profile diameter point and the following maximum diameter point of the profile;
• the radii of said rounded portions containing the points of maximum profile diameter and of minimum profile diameter are at least equal to 0.4 mm.
• the axial distance between 2 consecutive points of maximum profile diameter is at least equal to 1 mm and the axial distance between 2 consecutive points of minimum profile diameter is at least equal to 1 mm.
• said radial interference fit is substantially constant from one rib to the other;
• said radial interference fit is about 0.4 mm in diameter for a nominal threaded element diameter of 177.8 mm;
• said transfer surfaces are in mutual metal/metal sealing contact;
• a sealing material in the form of a coating or of an added ring is interposed between the metal surfaces of the male and female elements in the transfer zone;
• the male and female transfer surfaces or their envelopes form part of tapered surfaces;
• the transfer surfaces or their envelopes are inclined with respect to the connection axis by an angle comprised between 0.5 and 5°.
• said undulated surface has a roughness Ra ≤ 3.2 micrometers.
• the male transfer surface is adjacent to the regular portion of a great length tube at one end of which the male tubular element is formed;
• said undulated surface and said smooth surface form part of the male and female elements respectively;
• the outer peripheral surface of the female element has a depression which locally reduces its external diameter facing the transfer zone;
• said depression has an axially extending concave curvilinear profile facing the transfer zone and either side thereof, said external diameter being minimal substantially facing a median point of the transfer zone and increasing progressively to either side of said point;
• said curvilinear concave profile is connected to a chamfer adjacent to the free end of the female element;
• said minimum external diameter is such that the bending inertia of the female element in the plane of said minimum diameter is at least equal to the product of the bending inertia I_ZZ of the regular portion of a great length tube at one end of which the male tubular element is formed and the fraction f of the bending moment to be transferred;
• said concave curvilinear profile has a radius of curvature of at least 50 mm and preferably at least 100 mm;
• the female element forms part of a short coupling each end of which is provided with a female threaded element which can receive a male threaded element forming part of a great length tube for connecting the two tubes.

[0016] The invention also provides a process to improve the resistance to fatigue of a threaded tubular connection subjected to dynamic bending loads, said connection comprising a male tubular element with a male threaded portion and a female tubular element with a female threaded portion, characterized in that the connection comprises at least a transfer zone axially located between said threaded portions and the free end of one of said tubular elements while being axially spaced from said threaded portions so as to transfer from one element to the other element a fraction at least equal to 20 % of the bending moment undergone by the connection, the male and female elements having in said transfer zone respective transfer surfaces which are in mutual contact and interfere radially, one at least of the transfer surfaces comprising means suited for spacing radially the contact locations from the section where the stresses applied to the connection run, in particular in the form of a series of rounded annular ribs.

[0017] The characteristics and advantages of the invention will now be described in more detail in the following description, made with reference to the accompanying drawings.

Figure 1 is an axial half-sectional view of a threaded tubular connection of the invention;

Figure 2 is a partial axial sectional view on a larger scale of the male element of the threaded connection of Figure 1, showing a portion of the male transfer surface;

Figures 3 and 4 are explanatory diagrams illustrating the distribution of bending moments along the male element and the female element for a prior art threaded connection and for a threaded connection of the invention respectively.

[0018] The threaded tubular connection shown in Figure 1 comprises a male tubular element 1 and a female tubular element 2 provided with respective tapered threaded portions 3, 4 which cooperate for mutual makeup of the two elements. The element 1 is formed at one end of a great length tube 11 and element 2 is formed at one end of a tubular coupling 12 for connecting two tubes similar to 111. A plurality of tubes similar to 11 each one of which has two threaded elements similar to 1 at its ends can then be connected together through couplings similar to 12 each one of which has two threaded elements similar to 2 at its ends to form a string of tubes for an oil well, for example.

[0019] In the example shown, tube 11 has between its two male elements i.e. over the major portion of its length, termed the regular portion, a uniform external diameter ED of 177.8 mm (7 inches) which represents the nominal diameter of the threaded connection. The values for the dimensions given below take this nominal diameter into account and can vary therefrom.

[0020] According to the invention, the threaded tubular connection has a transfer zone which is axially defined by transverse planes P1 and P2, in which the male and female elements are in mutual contact through respective annular transfer surfaces 5, 6 of revolution around the axis A of the threaded portions; they have well defined profiles.

[0021] The profile of surface 5 is shown in Figure 2. The profile is an undulated periodic profile defined by repetition of a motif formed by three mutually tangential circular arcs, namely a first arc A1 which is outwardly convex, i.e. the concavity of which is turned towards the axis A, passing through a point P_M with a maximum profile diameter, a second concave arc A2 (the concavity of which is turned radially outwardly) passing through a point P_m with a minimum profile diameter, and a third convex arc A3, the radii of said three arcs being respectively 0.8, 1.6 and 8 mm in the example shown. The profile of surface 5 is also asymmetric, the axial distance d₁ between a point P_M with a maximum profile diameter and the following minimum diameter point P_m, starting from the free end 7 of the male element, i.e. from the right in Figure 2, being less than the axial distance d₂ between the point P_m and the following maximum diameter point P'_M of the profile. The distances d₁ and d₂ in this case are about 1 mm and 2 mm respectively.

[0022] The profile of surface 5 is generally inclined with respect to axis A, the straight lines L3 and L4 being respectively tangential to the set of arcs A1 and to the set of arcs A2, and thus constituting the outer and inner envelopes of said profile, being inclined at 2° with respect to said axis, growing closer thereto in the direction of the free end of the male element. Because of said inclination, the terms "maximum diameter point" and "minimum diameter point" refer to maximum and minimum diameters which are relative rather than absolute. The amplitude of the undulations in surface 5, i.e. the radial distance e between lines L3 and L4, is 0.2 mm.

[0023] The surface 6 of the female element facing surface 5, not shown in detail, is a tapered smooth surface the slope of which is equal to that of lines L3 and L4, so that the peaks of the different annular ribs 7 defined by surface 5 come into simultaneous contact with surface 6 when screwing the male threaded portion 3 into the female threaded portion 4. Advantageously, the dimensions of surfaces 5 and 6 are such that radial interference occurs at the end of screwing between the peaks of the ribs and the surface 6, said radial interference fit, i.e. the difference in diameter between the male and female elements measured prior to coupling at points which will come into interfering contact after makeup, being uniform from one rib to the other and advantageously being 0.4 mm.

[0024] Because of the undulated profile of surface 5, the contact surfaces between the crests of the ribs 7 and the surface 5 are radially spaced from the section defined between the cone the generatrix of which is L4 (internal envelope of the ribs) and the opposed peripheral surface (internal) of the male element 1 where the stresses applied to the connection are fully exerted (i.e. where they run), improving thus the resistance to fatigue of said connection when it is subjected to dynamic bending loads.

[0025] Too small an axial distance d₁ + d₂ (corresponding to the pitch of the ribs), for example smaller than 0.5 mm does not easily enable to form a sufficient undulation amplitude for the rounded portions under consideration. For that reason it is preferable to have an axial distance d₁ + d₂ over 1 mm. Nevertheless too large an axial distance d₁ + d₂ does not allow to house several ribs in the transfer zone unless said transfer zone is extended in an excessive way which is not cheaply produced.

[0026] Too small an inclination (lower than 0.5 °) of the lines L3, L4 makes difficult the sliding of the surfaces 5, 6 one against each other during make up of elements 1, 2 in particular because of the desired interference between the surfaces. An inclination above or equal to 1° is even preferable. An inclination above 5° is not desirable because it reduces too much the critical section of the male element 1 (minimum section of the element on which the whole of the axial loads are exerted on the connection) with respect to the section of the regular portion of the tube 11 and in consequence the efficiency of the connection.

[0027] Too low an undulation amplitude, for example lower than 0.5 mm does not allow to distance the section contacts where the axial stresses are exerted neither does it allow to store the wear debris as will be seen further on.

[0028] Too big an undulation amplitude reduces the critical section with the drawbacks mentioned above.

[0029] Moreover because of the undulated profile there remains between surfaces 5 and 6, between two consecutive ribs 7 annular spaces which can receive lubricating grease and/or debris formed by wear of the threaded elements during dynamic loadings. Further, each rib 7 defines an annular sealing contact surface with the surface 6, the multiplicity of said sealing surfaces reducing the risk of loss of a seal between the threaded portion zone 3, 4 and the outside of the threaded connection. This seal can be produced by direct contact of the constituent metallic materials of the male and female elements. In a variation, a sealing material such as an elastomer or a softer metal than that of the male and female elements (for example copper on steel) may be interposed between the substrate materials in the form of a coating or of an added ring. A further possibility consists of subjecting one and/or other of the contact surfaces to a surface treatment which encourages a seal.

[0030] Too small a radial interference between the crests of the ribs and surface 6 does not allow a seal between surfaces 5 and 6. Too large a radial interference risks inducing galling between surfaces 5 and 6 during make up, which galling is detrimental to the behavior to fatigue of the connection and to the seal between surfaces 5 and 6.

[0031] In order to obtain a good seal between surfaces 5 and 6, it is preferable to master the roughness of said surfaces. A roughness Ra > 3.2 micrometers is not desirable. For instance one can choose a roughness Ra ≤ 1.6 micrometers.

[0032] The advantages of the invention are particularly well illustrated in Figures 3 and 4, the top part of each of which shows a half-sectional view of the male element of a threaded tubular connection and the lower portion of which shows curves representing the variation along the axis A of the connection of the bending moments experienced by the male and female elements.

[0033] In Figure 3, which pertains to the prior art, male threaded portion 3 extends from a transverse plane P3 close to the free end 8 of the male element 1 to a transverse plane P4 which is directly followed by the regular portion 21 of the tube 11 to which the male element 1 belongs. When a bending load is applied to the tubular connection of which element 1 forms a part, this latter experiences a bending moment which varies along the axis A, following the curve C1, shown as a straight line. This moment M has a maximum value M₀ in the plane P4. Conversely, the bending moment experienced by the female element, not shown, varies as the curve C2, shown as a straight line, that moment being zero in the plane P4 and increasing progressively in the direction of the free end 8.

[0034] In Figure 4, which pertains to the invention, the bending moment M experienced by the male element 1 takes a maximum value M₀ in the plane P2 which separates the transfer surface 5 and the regular portion 21 of the tube 11. The bending moment experienced by the threaded portion 3 has a maximum value M₁ in the plane P4 which defines the threaded portion 3 opposite the free end 8 of the male element. The further the transfer zone 5, 6 is spaced from threaded portions 3, 4, and as a result from plane P2 and plane P4, the lower the value M₁ with respect to the value M₀.

[0035] In the case shown in Figure 4, the maximum diameter of the transfer surface 5 is equal to the diameter of the regular portion 21 of the tube 11.

[0036] The example below illustrates the manner by which the axial position of the transfer zone can be determined to obtain the effects sought by the invention.

[0037] We shall calculate the distance d between the centre of the transfer zone and the centre of the threaded portions to transfer a fraction f= 0.5 of the bending moment experienced by the connection from one element to the other. This distance is given by equation (1), in which F represents the force on the transfer zone resulting from the bending moment and M_max represents the maximum value of the bending moment which can be applied without permanent deformation of the connection:

[0038] The value M_max is given by equation (2) (the formula for the strength of a material) in which YS represents the yield strength of the material of the connection, I_ZZ represents the inertia of the cross section of the connection and OD represents the external diameter of the regular portion 21 of the tube 11:

[0039] I_ZZ is provided by equation (3), in which ID represents the internal diameter of the threaded connection:

[0040] F equals the product of an area S of the transfer zone and the maximum pressure stress to be applied to this zone, which equals the yield strength YS multiplied by a fraction f' which must not be exceeded.

[0041] S is the projection in an axial plane of the surface area in contact in the transfer zone, and is given by equation (4) in the case of a tapered transfer zone in which D₁ is the diameter of the cylindrical surface 17 (Figure 1) of the female element 2 connecting the threaded portion 4 and the transfer surface area 6, and α is the apex half-angle of the tapered surface containing the transfer surfaces 5, 6 and/or their envelopes:

[0042] Starting from the following data:

OD =

177.8 mm

ID =

157.08 mm

D₁ =

175.95 mm

YS =

551 MPa

f =

0.5

f' =

0.3

α =

2°

the following values can be calculated:

M_max =

119 × 10⁶ N.mm

S =

4685 mm²

D =

76.8 mm

[0043] In the example shown in Figure 1, this distance represents substantially 150% of the axial length of the female threaded portion, which is 51 mm, the axial length of the transfer zone being 13.2 mm.

[0044] More particularly but not exclusively in the case shown in Figure 1 in which the female element forms part of a coupling, the invention also encompasses reducing the thickness of said element, in the region facing the contact surfaces 5 and 6, to increase its flexibility. To this end, a depression 13 is formed on the outer peripheral surface 14 of the coupling, said depression having the profile of a large radius concave circular arc (more than 50 mm), in this case equal to 150 mm. This depression defines a minimum external diameter Dm facing a median point P of the transfer zone 5, 6, the external diameter increasing progressively either side of said point. Opposite the free end 15 of the element 2, the depression 13 connects to the cylindrical portion, with a maximum diameter, of the external surface 14. On the free end 15 side, the depression 13 connects to a chamfer 16 adjacent to the end 15. Advantageously, the minimum diameter of said chamfer, i.e. the diameter of element 2 at the junction between the chamfer 16 and the end face 15, is substantially equal to the diameter Dm of the bottom of the depression.

[0045] The diameter Dm is also selected so as not to have the bending inertia of the female element in the corresponding plane less than the product of the bending inertia I_ZZ of the regular portion of the tube 11 and the fraction f of the bending moment to be transferred.

[0046] While the transfer zone of the invention has been described in combination with a depression on the outer surface of a coupling, the transfer zone can be produced independently of the depression, in particular in the case of a connection which is termed an integral connection in which the male and female elements both form part of great length tubes.

Claims

1. A threaded tubular connection for a tubular string which is subjected to dynamic bending loads, comprising a male tubular element (1) provided with a male threaded portion (3) and a female tubular element (2) provided with a female threaded portion (4), characterized in that it comprises at least one dynamic bending load transfer zone axially disposed between said threaded portions and the free end of one of said tubular elements, while being axially spaced from said threaded portions (3, 4) so as to transfer a fraction of at least 20%, preferably at least 30% of the bending moment to which the connection is subjected from one element to the other, the male and female elements (1, 2) having respective transfer surfaces (5,6) in mutual contact with a radial interference fit in said transfer zone, at least one of the transfer surfaces being an undulated surface (5) defining a series of annular rounded ribs (7) which come into interfering contact with the facing transfer surface (6), the points (P_M, P_m) of maximum diameter and mininium diameter of the undulation profile being located on respective rounded portions (A1, A2) of the profile, transfer zone being axially disposed between said threaded portions (3,4) and the free end (15) of the female element.

2. A threaded connection according to claim 1, in which said free end of one of the tubular elements has a front surface which is free of contact with the other tubular element.

3. A threaded connection according to claim 1 or claim 2, in which the axial length of the transfer zone is selected so as to limit the contact pressure resulting from transferring the bending moment to a fraction of the yield strength of the material which is less than 1 and preferably less than 0.5.

4. A threaded connection according to one of the preceding claims, in which said male and female transfer surfaces (5, 6) are lubricated.

5. A threaded connection according to one of the preceding claims, in which said facing transfer surface (6) is a smooth surface.

6. A threaded connection according to claim 5, in which said undulated surface (5) is out of contact with said smooth surface between said ribs.

7. A threaded connection according to one of the preceding claims, in which the two transfer surfaces are undulated surfaces.

8. A threaded connection according to claim 7, in which the ribs of a transfer surface are housed between the ribs of the facing transfer surface.

9. A threaded connection according to one of the preceding claims, in which said undulated surface or surfaces (5) has/have a periodic profile.

10. A threaded connection according to claim 9, in which said periodic profile is asymmetric.

11. A threaded connection according to one of the preceding claims, in which said profile forms part of the male transfer surface and is defined by a first convex rounded portion (A1) containing a point (P_M) with a maximum profile diameter, by a second concave rounded portion (A2) containing a point (P_m) with a minimum profile diameter and which is tangential to the first rounded portion, and by a third convex rounded portion (A3) which is tangential to the first and second rounded portions and which has a radius (R3) which is substantially larger than the radius of the first and second rounded portions.

12. A threaded connection according to claim 11, in which the second rounded portion has a larger radius (R2) than the first rounded portion.

13. A threaded connection according to one of claims 11 and 12, in which starting from the free end of the male element, the axial distance (d1) between a maximum profile diameter point (P_M) and the following minimum diameter point (P_m) of the profile is less than the axial distance (d2) between a minimum profile diameter point and the following maximum diameter point (P'_M) of the profile.

14. A threaded connection according to claim 13, in which the third rounded portion is located between a minimum profile diameter point (P_m) and the following maximum diameter point (P'_M) of the profile.

15. A threaded connection according to one of the preceding claims, in which the radii (R1, R2) of said rounded portions (A1, A2) containing the points (P_M, Pm) of maximum diameter and of minimum diameter of the profile are at least equal to 0.4 mm.

16. A threaded connection according to one of the preceding claims, in which the axial distance (dl + d2) between two consecutive points (P_M) of maximum diameter of the profile is as least equal to 1 mm and in which the axial distance (dl + d2) between two consecutive points (Pm) of minimum diameter of the profile is at least equal to 1 mm.

17. A threaded connection according to one of the preceding claims, in which said radial interference fit is substantially constant from one rib to the other.

18. A threaded connection according to claim 17, in which said radial interference fit is about 0.4 mm in diameter for a nominal threaded element diameter of 177.8 mm.

19. A threaded connection according to one of the preceding claims, in which said transfer surfaces (5,6) are in mutual metal/metal sealing contact.

20. A threaded connection according to one of claims 1 to 18, in which a sealing material in the form of a coating or of an added ring is interposed between the metal surfaces of the male and female elements in the transfer zone.

21. A threaded connection according to one of the preceding claims, in which the male and female transfer surfaces (5,6) or their envelopes form part of tapered surfaces.

22. A threaded connection according to one of the preceding claims, in which the transfer surfaces or their envelopes are inclined with respect to the axis (A) of the connection by an angle comprised between 0.5 and 5°.

23. A threaded connection according to one of the preceding claims, in which said undulated surface (5) has a roughness Ra at most equal to 3.2 micrometers.

24. A threaded connection according to one of the preceding claims, in which the male transfer surface (5) is adjacent to the regular portion of a great length tube (11) at one end of which the male tubular element is formed.

25. A threaded connection according to one of the preceding claims dependent on claim 5, in which said undulated surface (5) and said smooth surface (6) form part of the male (1) and female (2) elements respectively.

26. A threaded connection according to one of the preceding claims in which the outer peripheral surface (14) of the female element has a depression (13) which locally reduces its external diameter facing the transfer zone (5, 6).

27. A threaded connection according to claim 26, in which said depression (13) has an axially extending concave curvilinear profile facing the transfer zone (5, 6) and either side thereof, said external diameter being minimal (Dm) substantially facing a median point (P) of the transfer zone and increasing progressively to either side of said point.

28. A threaded connection according to claim 27, in which said curvilinear concave profile is connected to a chamfer (16) adjacent to the free end (15) of the female element

29. A threaded connection according to claim 27 or claim 28, in which said minimum external diameter (Dm) is such that the bending inertia of the female element in the plane of said minimum diameter is at least equal to the product of the bending inertia IZZ of the regular portion of a great length tube (11) at one end of which the male tubular element is formed and the fraction f of the bending moment to be transferred.

30. A threaded connection according to one of claims 27 to 29, in which said concave curvilinear profile has a radius of curvature of at least 50 mm and preferably at least 100 mm.

31. A threaded connection according to one of the preceding claims, in which the female element (2) forms part of a short coupling (12) each end of which is provided with a female threaded element which can receive a male threaded element forming part of a great length tube (11) for connecting the two tubes.

Ansprüche

1. Rohrförmige Gewindeverbindung für eine dynamischen Biegebeanspruchungen ausgesetzte Rohrleitung, umfassend eine mit einem Außengewindeabschnitt (3) versehene männliche rohrförmige Komponente (1) und eine mit einem Innengewindeabschnitt (4) versehene weibliche rohrförmige Komponente (2), dadurch gekennzeichnet, dass diese zumindest einen axial zwischen den Gewindeabschnitten und dem freien Ende von einer der rohrförmigen Komponenten angeordneten Bereich zur Übertragung der dynamischen Biegebeanspruchung umfasst, der von den Gewindeabschnitten (3, 4) axial so beabstandet ist, das er wenigstens 20%, vorzugsweise wenigstens 30% des auf die Verbindung einwirkenden Biegemoments von einer Komponente auf die andere überträgt, wobei die männliche und die weibliche Komponente (1, 2) jeweils Übertragungsflächen (5, 6) aufweisen, die sich in einer Presspassung in dem Übertragungsbereich gegenseitig berühren, wobei wenigstens eine der Übertragungsflächen als wellenförmige Oberfläche (5) ausgebildet ist, die eine Reihe ringförmiger, gerundeter Rippen (7) bildet, die mit der gegenüberliegenden Übertragungsfläche (6) einen Presssitz ausbilden, wobei die Punkte (P_M, P_m) mit maximalem Durchmesser und mit minimalem Durchmesser des Wellenprofils an entsprechend gerundeten Abschnitten (A1, A2) des Profils angeordnet sind, wobei der Übertragungsbereich axial zwischen den Gewindeabschnitten (3, 4) und dem freien Ende der weiblichen Komponente angeordnet ist.

2. Gewindeverbindung nach Anspruch 1, worin das freie Ende von einer der rohrförmigen Komponenten eine Stirnfläche aufweist, die die andere rohrförmige Komponente nicht berührt.

3. Gewindeverbindung nach Anspruch 1 oder Anspruch 2, worin die axiale Länge des Übertragungsbereichs so gewählt ist, dass der sich aus der Übertragung des Biegemoments ergebende Anpressdruck auf einen Bruchteil der Materialstreckgrenze begrenzt ist, der weniger als 1 und vorzugsweise weniger als 0,5 beträgt.

4. Gewindeverbindung nach einem der vorangehenden Ansprüche, worin die weibliche und die männliche Übertragungsfläche (5, 6) geschmiert ist.

5. Gewindeverbindung nach einem der vorangehenden Ansprüche, worin die gegenüberliegende Übertragungsfläche (6) glatt ausgebildet ist.

6. Gewindeverbindung nach Anspruch 5, worin die wellenförmige Oberfläche (5) die glatte Oberfläche zwischen den Rippen nicht berührt.

7. Gewindeverbindung nach einem der vorangehenden Ansprüche, worin beide Übertragungsflächen wellenförmig ausgebildet sind.

8. Gewindeverbindung nach Anspruch 7, worin die Rippen einer Übertragungsfläche zwischen den Rippen der gegenüberliegenden Übertragungsfläche angeordnet sind.

9. Gewindeverbindung nach einem der vorangehenden Ansprüche, worin die wellenförmige Oberfläche bzw. die wellenförmigen Oberflächen (5) ein periodisches Profil aufweist bzw. aufweisen.

10. Gewindeverbindung nach Anspruch 9, worin das periodische Profil asymmetrisch ausgebildet ist.

11. Gewindeverbindung nach einem der vorangehenden Ansprüche, worin das Profil einen Teil einer männlichen Übertragungsfläche bildet und von einem ersten konvex gerundeten Abschnitt (A1), der einen Punkt (P_M) mit maximalem Profildurchmesser enthält, von einem zweiten konkav gerundeten Abschnitt (A2), der einen Punkt (P_m) mit minimalem Profildurchmesser enthält und der tangential an den ersten gerundeten Abschnitt anschließt, und von einem dritten konvex gerundeten Abschnitt (A3) bestimmt ist, der tangential an den ersten und zweiten gerundeten Abschnitt anschließt und einen wesentlich größeren Radius (R3) aufweist.

12. Gewindeverbindung nach Anspruch 11, worin der zweite gerundete Abschnitt einen größeren Radius (R2) als der erste gerundete Abschnitt aufweist.

13. Gewindeverbindung nach einem der Ansprüche 11 oder 12, worin ausgehend vom freien Ende der männlichen Komponente, der axiale Abstand (d1) zwischen einem Punkt (P_M) maximalen Profildurchmessers und dem anschließenden Punkt (P_m) minimalen Profildurchmessers kleiner ist als der axiale Abstand (d2) zwischen einem Punkt minimalen Profildurchmessers und dem anschließenden Punkt (P'_M) maximalen Profildurchmessers.

14. Gewindeverbindung nach Anspruch 13, worin der dritte gerundete Abschnitt zwischen einem Punkt (P_m) minimalen Profildurchmessers und dem anschließenden Punkt (P'_M) maximalen Profildurchmessers angeordnet ist.

15. Gewindeverbindung nach einem der vorangehenden Ansprüche, worin die Radien (R1, R2) der gerundeten Abschnitte (A1, A2), die die Punkte (P_M, P_m) maximalen Profildurchmessers und minimalen Profildurchmessers enthalten, zumindest 0,4 mm betragen.

16. Gewindeverbindung nach einem der vorangehenden Ansprüche, worin der axiale Abstand (d1 + d2) zwischen zwei aufeinander folgenden Punkten (P_M) maximalen Profildurchmessers wenigsten 1 mm beträgt, und worin der axiale Abstand (d1 + d2) zwischen zwei aufeinander folgenden Punkten (P_m) minimalen Profildurchmessers wenigsten 1 mm beträgt.

17. Gewindeverbindung nach einem der vorangehenden Ansprüche, worin das radiale Übermaß der Presspassung von einer zur anderen Rippe im wesentlichen konstant ist.

18. Gewindeverbindung nach Anspruch 17, worin das radiale Übermaß der Presspassung bei einem Nominaldurchmesser der mit einem Gewinde versehene Komponente von 177,8 mm in etwa 0,4 mm im Durchmesser beträgt.

19. Gewindeverbindung nach einem der vorangehenden Ansprüche, worin die Übertragungsflächen (5, 6) gemeinsam einen Metall - auf - Metall - Dichtkontakt ausbilden.

20. Gewindeverbindung nach einem der Ansprüche 1 bis 18, worin ein Dichtungsmaterial in Form einer Beschichtung oder eines zusätzlichen Rings zwischen den Metalloberflächen in dem Übertragungsbereich von männlicher und weiblicher Komponente angeordnet ist.

21. Gewindeverbindung nach einem der vorangehenden Ansprüche, worin die männliche und die weibliche Übertragungsfläche (5, 6) oder deren Einhüllenden Teile konisch zulaufender Oberflächen bilden.

22. Gewindeverbindung nach einem der vorangehenden Ansprüche, worin die Übertragungsflächen oder deren Einhüllenden gegenüber der Achse (A) der Verbindung um einen Winkel im Bereich von 0,5 bis 5° geneigt sind.

23. Gewindeverbindung nach einem der vorangehenden Ansprüche, worin die wellenförmige Oberfläche (5) eine Rauhigkeit Ra von maximal 3,2 Mikrometern aufweist.

24. Gewindeverbindung nach einem der vorangehenden Ansprüche, worin die männliche Übertragungsfläche (5) an ein Langrohr (11) angrenzt, an dessen einem Ende die männliche rohrförmige Komponente ausgebildet ist.

25. Gewindeverbindung nach einem der vorangehenden Ansprüche soweit auf Anspruch 5 rückbezogen, worin die wellenförmige Oberfläche (5) und die glatte Oberfläche (6) Teil einer männlichen bzw. weiblichen Komponente bilden.

26. Gewindeverbindung nach einem der vorangehenden Ansprüche, worin die äußere Umfangsfläche (14) der weiblichen Komponente eine Einsenkung (13) aufweist, an der sich deren Außendurchmesser in Richtung des Übertragungsbereichs (5, 6) lokal verjüngt.

27. Gewindeverbindung nach Anspruch 26, worin die Einsenkung (13) ein sich in Richtung des Übertragungsbereichs (5, 6) axial erstreckendes konkav gekrümmtes Profil aufweist, wobei an einer der Seiten davon der minimale Außendurchmesser (D_m) in etwa einem mittleren Punkt (P) des Übertragungsbereichs gegenüberliegt und zu beiden Seiten des Punkts kontinuierlich zunimmt.

28. Gewindeverbindung nach Anspruch 27, worin das konkav gekrümmte Profil an eine an das freie Ende (15) der weiblichen Komponente angrenzende Fase (16) anschließt.

29. Gewindeverbindung nach Anspruch 27 oder Anspruch 28, worin der minimale Außendurchmesser (D_m) so ausgebildet ist, dass das Flächenträgheitsmoment der weiblichen Komponente in der Ebene mit dem minimalen Durchmesser zumindest dem Produkt aus dem Flächenträgheitsmoment IZZ des gleichmäßigen Abschnitts eines Langrohrs (11), an dessen einem Ende eine männliche rohrförmige Komponente ausgebildet ist, und dem Bruchteil f des zu übertragenden Biegemoments entspricht.

30. Gewindeverbindung nach einem der Ansprüche 27 bis 28, worin das konkav gekrümmte Profil einen Krümmungsradius von wenigstens 50 mm und vorzugsweise von wenigstens 100 mm aufweist.

31. Gewindeverbindung nach einem der vorangehenden Ansprüche, worin die weibliche Komponente (2) einen Teil einer Kurzkupplung (12) bildet, deren beide Enden zum Verbinden von zwei Rohren jeweils mit einer Innengewindekomponente versehen sind, die eine als Teil eines Langrohrs (11) ausgebildete Außengewindekomponente aufnehmen kann.

Revendications

1. Joint fileté tubulaire pour colonne tubulaire soumise à des efforts dynamiques de flexion, comprenant un élément tubulaire mâle (1) comportant un filetage mâle (3), et un élément tubulaire femelle (2) comportant un filetage femelle (4), caractérisé en ce qu'il comporte au moins une zone de transfert de charges dynamiques de flexion disposée axialement entre lesdits filetages et l'extrémité libre de l'un desdits éléments tubulaires en étant écartée axialement desdits filetages (3, 4) de manière à transférer d'un élément à l'autre une fraction au moins égale à 20 %, et préférentiellement à 30 %, du moment de flexion subi par le joint, les éléments mâle et femelle (1, 2) présentant dans ladite zone de transfert des surfaces de transfert respectives (5, 6) en contact mutuel avec serrage radial, l'une au moins des surfaces de transfert étant une surface ondulée (5) définissant une série de nervures annulaires arrondies (7) qui viennent en contact serrant avec la surface de transfert en regard (6), les points (PM, Pm) de diamètre maximal et de diamètre minimal du profil ondulé étant disposés sur des arrondis respectifs (A₁, A₂) du profil, ladite zone de transfert étant disposée axialement entre lesdits filetages (3, 4) et l'extrémité libre (15) de l'élément femelle.

2. Joint fileté selon la revendication 1, dans lequel ladite extrémité libre de l'un des éléments tubulaires présente une surface frontale exempte de contact avec l'autre élément tubulaire.

3. Joint fileté selon l'une des revendications 1 et 2, dans lequel la longueur axiale de la zone de transfert est choisie de manière à y limiter la pression de contact résultant du transfert du moment de flexion à une fraction de la limite d'élasticité du matériau inférieure à 1 et préférentiellement inférieure à 0,5.

4. Joint fileté selon l'une des revendications précédentes, dans lequel lesdites surfaces de transfert mâle et femelle (5, 6) sont lubrifiées.

5. Joint fileté selon l'une des revendications précédentes, dans lequel ladite surface de transfert en regard (6) est une surface lisse.

6. Joint fileté selon la revendication 5, dans lequel ladite surface ondulée (5) est hors de contact avec ladite surface lisse entre lesdites nervures.

7. Joint fileté selon l'une des revendications précédentes, dans lequel les deux surfaces de transfert sont des surfaces ondulées.

8. Joint fileté selon la revendication 7, dans lequel les nervures d'une surface de transfert sont logées entre les nervures de la surface de transfert en regard.

9. Joint fileté selon l'une des revendications précédentes, dans lequel ladite ou lesdites surfaces ondulées (5) présentent un profil périodique.

10. Joint fileté selon la revendication 9, dans lequel ledit profil périodique est asymétrique.

11. Joint fileté selon l'une des revendications précédentes, dans lequel ledit profil appartient à la surface mâle de transfert et est défini par un premier arrondi convexe (A1) passant par un point (P_M) de diamètre maximal du profil, un second arrondi concave (A2) passant par un point (P_m) de diamètre minimal du profil et tangent au premier arrondi et un troisième arrondi convexe (A3) tangent aux premier et second arrondis et présentant un rayon (R3) sensiblement plus grand que les rayons des premier et second arrondis.

12. Joint fileté selon la revendication 11, dans lequel le second arrondi présente un plus grand rayon (R2) que le premier arrondi.

13. Joint fileté selon l'une des revendications 11 et 12, dans lequel, en partant de l'extrémité libre de l'élément mâle, la distance axiale (d₁) entre un point (P_M) de diamètre maximal du profil et le point (P_m) de diamètre minimal suivant du profil est inférieure à la distance axiale (d₂) entre un point de diamètre minimal du profil et le point (P'_M) de diamètre maximal suivant du profil.

14. Joint fileté selon la revendication 13, dans lequel le troisième arrondi se situe entre un point (P_m) de diamètre minimal du profil et le point (P'_M) de diamètre maximal suivant du profil.

15. Joint fileté selon l'une des revendications précédentes, dans lequel les rayons (R1, R2) desdits arrondis (A1, A2) contenant les points (P_M, Pm) de diamètre maximum et de diamètre minimum du profil sont au moins égaux à 0,4 mm.

16. Joint fileté selon l'une des revendications précédentes, dans lequel la distance axiale (d1 + d2) entre deux points consécutifs (P_M) de diamètre maximal du profil est au moins égal à 1 mm et dans lequel la distance (d1 + d2) entre deux points consécutifs (Pm) de diamètre minimum du profil est au moins égal à 1 mm.

17. Joint fileté selon l'une des revendications précédentes, dans lequel ledit serrage radial est sensiblement constant d'une nervure à l'autre.

18. Joint fileté selon la revendication 17, dans lequel ledit serrage radial est d'environ 0,4 mm en diamètre pour un diamètre nominal des éléments filetés de 177,8 mm.

19. Joint fileté selon l'une des revendications précédentes, dans lequel lesdites surfaces de transfert (5, 6) sont en contact mutuel étanche métal/métal.

20. Joint fileté selon l'une des revendications 1 à 18, dans lequel un matériau d'étanchéité sous forme d'un revêtement ou d'une bague rapportée est interposé entre les surfaces métalliques des éléments mâle et femelle dans la zone de transfert.

21. Joint fileté selon l'une des revendications précédentes, dans lequel les surfaces de transfert mâle et femelle (5, 6) ou leurs enveloppes appartiennent à des surfaces coniques.

22. Joint fileté selon l'une des revendications précédentes, dans lequel les surfaces de transfert ou leurs enveloppes sont inclinées d'un angle compris entre 0,5 et 5° par rapport à l'axe (A) du joint.

23. Joint fileté selon l'une des revendications précédentes, dans lequel ladite surface ondulée (5) présente une rugosité Ra au maximum égale à 3,2 micro mètres.

24. Joint fileté selon l'une revendications précédentes, dans lequel la surface de transfert mâle (5) est adjacente à la partie courante d'un tube de grande longueur (11) à une extrémité duquel est formé l'élément tubulaire mâle.

25. Joint fileté selon l'une des revendications précédentes, rattachée à la revendication 5, dans lequel ladite surface ondulée (5) et ladite surface lisse (6) appartiennent respectivement aux éléments mâle (1) et femelle (2).

26. Joint fileté selon l'une des revendications précédentes, dans lequel la surface périphérique extérieure (14) de l'élément femelle présente en regard de la zone de transfert (5, 6) une dépression (13) qui réduit localement son diamètre extérieur.

27. Joint fileté selon la revendication 26, dans lequel ladite dépression (13) présente un profil curviligne concave s'étendant axialement en regard de la zone de transfert (5, 6) et de part et d'autre de celle-ci, ledit diamètre extérieur étant minimal (Dm) sensiblement en regard d'un point médian (P) de la zone de transfert et croissant progressivement de part et d'autre de ce point.

28. Joint fileté selon la revendication 27, dans lequel ledit profil curviligne concave se raccorde à un chanfrein (16) adjacent à l'extrémité (15) libre de l'élément femelle.

29. Joint fileté selon l'une des revendications 27 et 28, dans lequel ledit diamètre extérieur minimal (Dm) est tel que l'inertie de flexion de l'élément femelle dans le plan de ce diamètre minimal est au moins égal au produit de l'inertie de flexion I_ZZ de la partie courante d'un tube de grande longueur (11) à une extrémité duquel est formé l'élément tubulaire mâle par la fraction f du moment de flexion à transférer.

30. Joint fileté selon l'une des revendications 27 à 29, dans lequel ledit profil curviligne concave présente un rayon de courbure au moins égal à 50 mm et préférentiellement à 100 mm.

31. Joint fileté selon l'une des revendications précédentes, dans lequel l'élément femelle (2) appartient à un manchon de faible longueur (12) muni à chaque extrémité d'un élément fileté femelle propre à recevoir un élément fileté mâle appartenant à un tube de grande longueur (11) pour le raccordement des deux tubes.

Drawing