METALLIC TUBULAR CONNECTING PART AND METHOD FOR OBTAINING SUCH A PART BY ADDITIVE MANUFACTURING

Abstract

A tubular metal connecting part (1) comprising a total axial length (LT), an inner surface (5) and an outer surface (6), wherein the inner (5) and outer (6) surfaces define a wall (7), an outer transition surface (SText) and an inner transition surface (STint) wherein the outer transition surface (SText) and the inner transition surface (STint) delimit a transition thickness (W) of the wall (7), wherein a first threaded end (2) is defined by a first portion of outer surface (P1ext) extending along a first axial length (L1), a second threaded end (3) is defined by a second portion of inner surface (P2int) extending along a second axial length (L2),wherein the connecting part (1) is characterized in that the sum of the first axial length (L1) and the second axial length (L2) is less than or equal to the total axial length (LT) of the connecting part (1).

Description

METALLIC TUBULAR CONNECTING PART AND METHOD FOR OBTAINING SUCH A PART BY ADDITIVE MANUFACTURING The present invention relates to tubular metal components in the field of oil and natural gas and, in particular, for use, for example, in the operation of hydrocarbon extraction wells or hydrocarbon transport, the geothermal field or carbon capture. More specifically, the present invention relates to a metallic tubular connecting part made, for example, of steel, intended to connect at least two metallic tubular components that are incompatible because their inner and / or outer diameter, thickness, and thread geometry are different. Such connecting parts (1) have a yield strength that is preferably greater than or equal to 550 MPa. For the purposes of the present invention, a connecting part is understood to mean a coupling or fitting, which is frequently referred to in the literature by one of the following terms: interconnector, circulating heads, circulating pipe straightener, or water sleeve. The present invention also relates to a method for obtaining a metallic tubular connector part by additive manufacturing. In the prior art, such metal tubular connecting parts have two threaded ends, usually of different diameters, and a transition portion that connects the two threaded ends and allows, where appropriate, a gradual change from one diameter to the other. These metal tubular connecting parts are obtained by subtractive manufacturing methods, in particular by various controlled machining and material removal processes (e.g., cutting or drilling) from thick solid metal bars, blocks, or tubes. The disadvantage of prior art connecting parts is their weight, which complicates the work of operators who must handle them, particularly during transport, handling, and use. Furthermore, the subtractive methods used to manufacture prior art connecting parts have several disadvantages. In particular, the greater the amount of material removed, the higher the manufacturing cost. As a result, with subtractive methods, manufacturers are forced to remove as little material as possible to optimize the cost of producing a part. This economic constraint leads to a technical constraint: a minimum amount of material is removed, resulting in significantly thicker walls in the transition portion of prior art connecting parts.In this transition portion, more material can be removed, which can reduce the part's weight and make it easier for operators to handle during transport, use, and handling. Instead of doing this, to save costs, the final part has a significant amount of excess material in its transition portion, making it heavier and more cumbersome. What's more, this excess material also represents a loss of material that could be reused in the manufacture of other parts. This material loss ultimately translates into an economic loss as well. To overcome the disadvantages of the connecting parts of the prior art, the object of the present invention relates to a tubular metallic connecting part having at least one axis of revolution (x) and a total axial length (Lr), wherein said connecting part comprises: - an interior surface and an exterior surface, where said interior and exterior surfaces define a wall, - at least one first exterior transition plane (Bext) and at least one second exterior transition plane (Dext), wherein both of said exterior transition planes (Bext) and (Dext) are orthogonal to the axis of revolution (x), - at least one first interior transition plane (A¡nt) and at least one second interior transition plane (Gnt), wherein both of said interior transition planes (A¡nt) and (C¡nt) are orthogonal to the axis of revolution (x), - an outer transition surface (SText) having a truncated conical shape defined by an outer transition generatrix (G) having an inclination of angle α to the axis of revolution (x), wherein said outer transition surface (SText) extends from the first outer transition plane (Bext) to the second outer transition plane (Dext), - an inner transition surface (ST¡nt) having a truncated conical shape defined by a transition generatrix (G) having an inclination angle a2 to the axis of revolution (x), wherein said transition surface (ST¡nt) extends from the first inner transition plane (A¡nt) to the second inner transition plane (D¡nt), wherein said transition surface (SText) and said inner transition surface (STmt) delimit a wall transition thickness (W), - a first male or female threaded end, having a first end plane (SI) orthogonal to the axis of revolution (x), a first inside diameter (IDi) and a first outside diameter (ODi), wherein said first end is defined by a first inside surface portion (Pl¡nt) of inside diameter (IDi) extending from the first end plane (SI) to the first transition plane (Amt), and by a first outside surface portion (Plext) of outside diameter (ODi) extending along a first axial length (Li) from the first end plane (SI) to the first outside transmission plane (Bext), wherein said first inside surface portion (Pl¡nt) has a substantially cylindrical shape defined by a first inside surface generatrix (Gl¡nt), and wherein said first outside surface portion (Plext) has a substantially cylindrical shape defined by a first outside surface generatrix (Glext),with oenn / eznz / E / YiAi, - a second male or female threaded end, having a second end plane (S2) orthogonal to the axis of revolution (x), a second inner diameter (ID2) and a second outer diameter (OD2), wherein said second end is defined by a second inner surface portion (P2int) of inner diameter (ID2) and extending along a second axial length (L?) from the second end plane (S2) to the second inner transition plane (Cint), and by a second outer surface portion (P2ext) of outer diameter (OD2) and extending from the second end plane (S2) to the second outer transition plane (Dext), wherein said inner surface portion (P2int) has a substantially cylindrical shape defined by a second inner surface generatrix (G2int),wherein said second portion of outer surface (P2ext) has a substantially cylindrical shape defined by a second generatrix of outer surface (G2ext), wherein the sum of the first and second axial lengths (Li) and (L2) is less than or equal to the total axial length (Lt) of the connecting part, wherein said connecting part is characterized in that the first end has a first wall thickness (El), wherein the second end has a second wall thickness (E2) and the transition thickness (W) satisfies the following equation: [Mathematics] 1 x max (El; E2) < W< 1.5 x max (El; E2) Where: max (El; E2) represents the largest selected value of the thickness (El) and (E2), and corresponds to (El) and (E2) when (El) and (E2) are equal. Thus, the wall thickness variations in the transition portion are low. In other words, the wall thickness in the transition portion is more homogeneous than in the connecting parts of the previous technique. In this patent application, the term "threaded end" means an end that has a thread along all or part of its length. Furthermore, in this patent application, the term "substantially cylindrical" refers to a tubular surface that may have surface irregularities, such as threads. Furthermore, in this patent application, the term axial length refers to any length along the axis of revolution (x). Thus, any element or portion of the connecting part that has an axial length is an element or portion that has an axis that is substantially zero with respect to the axis of revolution (x) of the connecting part. Such a relationship between the first and second axial lengths (Li) and (L2) is due to the order in which the transition planes follow one another along the axis of revolution (x), from the first end plane (SI) to the second end plane (S2). According to one embodiment, the planes (Bext) and (Cint) may be aligned. In such a case, the sum of the axial lengths (Li) and (L2) is equal to the total axial length (Lt) of the connecting part. According to an embodiment where the planes (Bext) and (Cnt) are not aligned, the plane (Ant) is closer to the plane (Bext) than to the plane (Cnt), and the plane (Dext) is closer to the plane (Gnt) than to the plane (Bext). In such a case, the sum of the axial lengths (Li) and (Lz) is strictly less than the total axial length (Lt) of the connecting part.This arrangement of the transition planes leads to a refinement of the wall portion located between the first interior surface transition plane (Ant) and the second exterior surface transition plane (Dext): this wall portion is referred to as the transition portion. This refinement results in a reduction of the wall thickness in the transition portion, as well as a reduction in the weight of the connecting part. The first and second end planes (SI) and (S2) are the planes that define the total axial length (Lt) of the connecting part. In other words, the connecting part extends along a total axial length (Lt) from the first end plane (SI) to the second end plane (S2). The first interior transition plane (A¡nt) is a cross-sectional plane of the connecting part. The plane (A¡nt) is orthogonal to the axis of revolution (x) and passes through the intersection between the first interior surface generatrix (Gl¡nt) and the interior transition generatrix (G). The first exterior transition plane (A¡nt) is a cross-sectional plane of the connecting part. The plane (Bext) is orthogonal to the axis of revolution (x) and passes through the intersection between the first exterior surface generatrix (Glext) and the exterior transition generatrix (G). The second interior transition plane (Cint) is a cross-sectional plane of the connecting part. The plane (Cnt) is orthogonal to the axis of revolution (x) and passes through the intersection between the second interior surface generatrix (G2int) and the interior transition generatrix (G). The second exterior transition plane (Dint) is a cross-sectional plane of the connecting part. The plane (Dext) is orthogonal to the axis of revolution (x) and passes through the intersection between the second exterior surface generatrix (G2ext) and the exterior transition generatrix (G). The transition thickness (W) corresponds to the thickness of the wall portion extending from the first outer transition plane (Bext) to the second inner transition plane (Cint). In other words, the transition thickness (W) extends along the entire wall portion where the outer transition surface (Sext) and the inner transition surface (Sint) overlap. The length of the transition thickness (W) is thus defined by the first outer transition plane (Bext) and the second inner transition plane (Cint). In this patent application, the term thickness, when referring to any portion of the wall, means a thickness measured along an axis perpendicular to at least one of the surfaces that delimit the wall in the portion under consideration, namely, one of the following surfaces: inner surface, outer surface, inner transition surface (ST¡nt) or outer transition surface (SText). cu oenn / eznz / E / YiAi The two generatrices of the inner surface (Glmt) and (G2¡nt), and the two generatrices of the outer surface (Glext) and (G2ext) all have a substantially zero angle to the axis of revolution (x). A substantially zero angle is understood here to mean an angle that is less than or equal to 2° to the axis of revolution (x). According to one modality, the first outside diameter (ODi) is different from the second outside diameter (OD2). According to one modality, the first inner diameter (IDi) is different from the second inner diameter (ID2). According to one modality, the first outside diameter (ODi) is different from the second outside diameter (OD2), and the first inside diameter (IDi) is different from the second inside diameter (ID2). According to one modality, the diameter (OD2) can be equal to the diameter (IDt). According to one modality, the first and second outside diameters (ODi) and (OD2) are between 25 mm and 950 mm. Preferably, the larger of the two outside diameters (ODi) and (OD2) is between 75 mm and 950 mm, and the smaller of the two outside diameters (ODi) and (OD2) is between 25 mm and 700 mm. According to one embodiment, the first and second inside diameters (ID 1) and (ID2) are between 20 mm and 900 mm. Preferably, the larger of the two inside diameters (IDi) and (ID2) is between 70 mm and 900 mm, and the smaller of the two inside diameters (IDi) and (ID2) is between 20 mm and 695 mm. Preferably, the difference between (ODi) and (OD2) is less than or equal to 500 mm and the difference between (IDi) and (ID2) is less than or equal to 500 mm. The first inner diameter (IDi) is measured in the vicinity of the first inner transition plane (Aint). The second inner diameter (ID2) is measured in the vicinity of the second inner transition plane (Cint). The first outer diameter (ODi) is measured in the vicinity of the first outer transition plane (Bext). The second outer diameter (OD2) is measured in the vicinity of the second inner transition plane (Dext). Thus, the inner and outer diameters of the first and second ends may vary. All the aforementioned features contribute, either individually or collectively, to reducing the wall thickness in the portion of the wall located between the first interior transition plane (A¡nt) and the second transition plane (Dext): this portion of the wall is referred to as the transition portion. According to one embodiment, the first end has at least one first unthreaded part, and the second end has at least one second unthreaded part. cm oenn / eznz / E / YiAi According to one embodiment, the first unthreaded part extends along a first unthreaded length (li) from the first inner transition plane (Aint), and the second unthreaded part extends along a second unthreaded length (b) from the second inner transition plane (Cint). The first and second unthreaded lengths (li) and (b) are axial lengths. Advantageously, each of the first and second unthreaded lengths (li) and (b) is greater than or equal to 150 mm. Such a length of the unthreaded parts allows the connecting part to be grasped or gripped by the tools normally used by operators to assemble, for example, by screwing, the connecting part to the at least two tubular components to be connected. According to one modality, the inner surface comprises the following parts from the first end plane (SI) to the second end plane (S2): - a first threaded or non-threaded part (Tl¡nt), - a first unthreaded cylindrical part, - a truncated conical part (ST¡nt), - a second unthreaded cylindrical part, and - a second threaded or non-threaded part (T2¡nt). According to one modality, the outer surface comprises the following parts from the first end plane (SI) to the second end plane (S2): - a first threaded or non-threaded part (Tlext), - a third unthreaded cylindrical part, - a truncated conical part (SText), - a quarter unthreaded cylindrical part, and - a second threaded or non-threaded part (T2ext). According to one modality, the first and second thicknesses (El) and (E2) are between 2 mm and 300 mm, more preferably between 2 mm and 150 mm, even more preferably between 2 mm and 75 mm. According to one modality, the first and second thicknesses (E1) and (E2) are such that |(E1) - (E2)| < 65 mm, preferably such that |(E1) - (E2)| < 40 mm, even more preferably such that |(E1) - (E2)| < 25 mm. Preferably, the first and second thicknesses (El) and (E2) are equal. According to one embodiment, the angles α1 and α2 are both between and inclusive of 100° and 300° with respect to the axis of revolution (x). This allows a fluid to flow optimally through the connecting part. Preferably, the angles α1 and α2 are both between and inclusive of 150° and 25°, and more preferably, α1 and α2 are both 20°. When the angles α1 and α2 are greater than 10°, a fluid can no longer flow optimally, and the connecting part loses effectiveness in its fluid-carrying function. When the angles α1 and α2 are less than 10°, the total axial length (Lt) of the part is too large and no longer meets the dimensional standards for this type of bushing. Since dimensional standards are established for the optimal handling and storage of this type of product, it is preferable to lengthen these bushings beyond the incidence of 10°, i.e., in such a way that the angles a1 and a2 are less than 10°. According to one modality, the angles a1 and a2 are such that |a1 - a2| < 5°. Preferably, the angles a1 and a2 are such that |a1 - a2| < 2°. More preferably, the angles a1 and a2 are such that |a1 - a2| < 0° and thus the outer transition surface (SText) and inner transition surface (ST¡nt) are substantially parallel to each other and the transition thickness (W) is substantially constant along its entire length. According to one modality, the transition thickness (W) is between 2 mm and 450 mm, preferably between 2 and 225 mm, more preferably between 3 mm and 75 mm, even more preferably between 7 mm and 25 mm. According to one modality, the total axial length (Lt) of a connecting part is between 0.3 m and 6 m, preferably between 0.3 m and 2.5 m, more preferably between 0.6 m and 1.5 m. The present invention further relates to a connecting part, the wall of which is produced, either wholly or partially, by additive manufacturing. Preferably, the wall is produced entirely by additive manufacturing. In accordance with ISO / ASTM 52900:2015(E), the term additive manufacturing is the general term for technologies that, based on a geometric representation, create physical objects by successively adding material. ISO / ASTM 52900:2015(F) defines additive manufacturing as follows: the process of joining materials to produce parts from 3D model data, typically layer upon layer, as opposed to subtractive and formative manufacturing methodologies. The inventors have found that the invention allows for homogeneous heat treatment of the connecting portion, particularly the transition portion, due to the homogeneity of the wall thickness. This is not the case in the prior art because the lack of homogeneity in the wall thickness of the transition portion is such that the effects of heat treatment on the connecting portion will inevitably result in heterogeneities within the transition portion. Surprisingly, the inventors have also found that, due to the homogeneity of the wall thickness in the transition portion, a non-destructive ultrasonic test can also be performed on the connecting part of the invention. The non-destructive ultrasonic test aims to detect defects in the wall of a part by emitting ultrasonic signals and detecting their reflections at acoustic interfaces within the wall thickness. More specifically, the dimensions, shape, and location of a defect are determined as a function of the time elapsed between the emission of an ultrasonic signal at a specific location on the part's wall and the detection of its reflection at another specific location on the wall.Thus, when the wall has significant thickness variations between the point of signal emission and the point of signal detection, the reflected signal can originate from a variety of emitted ultrasound paths, making it difficult to isolate it from other signals. Consequently, the detected signal cannot be used to assess the defect to be identified. Such measurements are therefore unreliable when the wall of a connected part has significant thickness variations, to the point that some areas, particularly the transition portion, cannot be inspected due to the presence of returned ultrasonic paths related to the part's geometry in the transition portion, specifically the wall thickness and the inclination angles of the inner and outer transition surfaces. Thus, in the prior art, non-destructive ultrasonic testing can be performed on the connected part.Thus, it is only carried out on the metal block before it is subjected to conventional subtractive methods, and the final part is never ultrasonically tested, thus leaving possible defects in the part wall after manufacturing. An additional objective of the invention relates to a method for obtaining a connecting part comprising at least: i. a step of producing the wall completely or partially by additive manufacturing, ii. a step of machining the first and second ends. Such a method makes it possible to dispense with subtractive methods, at least for obtaining the wall. The wall thus constitutes a preform that is threaded into the machining step (i) using methods of the prior art. Such a method makes it possible to limit the amount of material required to obtain the wall, thereby avoiding the material waste normally generated by subtractive methods. According to the invention, step (i) can be carried out by one of the following additive manufacturing methods belonging to the Direct Energy Deposition category as defined by ASTM F2792, such as Laser Metal Deposition (LMD), Wire Arc Additive Manufacturing (WAAM), or any other method that can be qualified as a Direct Energy Deposition method. According to one modality, the method comprises a third step (iii) of heat treatment of the connecting part. According to one modality, the machining step (i) comprises machining cu oenn / eznz / E / YiAi all surfaces of the part and can be carried out before or after the heat treatment step. Other features and advantages of the invention will become apparent upon examination of the following detailed description provided below, and from the accompanying drawings. [Figure 1]: Figure 1 shows a diagram of a longitudinal section view of a connecting part of the prior art; [Figure 2]: Figure 2 shows a diagram of a longitudinal sectional view of a connecting part according to an embodiment of the invention; The accompanying drawings may be used not only to supplement the invention, but also to contribute to its definition, where applicable. They do not limit the scope of the invention. Figure 1 shows a diagram of a longitudinal sectional view of a connecting part (1) of the prior art. The connecting part comprises a shaft of revolution (x), a total axial length (Lt), a wall (7), an inner surface (5) and an outer surface (6), a first threaded end (2) and a second threaded end (3), as well as a transition portion (4). The transition portion (4) extends from a first transition plane (A¡nt) to the second transition plane (Dext). The first end (2) is defined by a first end plane (SI) and a first outer surface portion (Plext) that extends along a first axial length (Li) from the first end plane (SI) to a first outer transition plane (Bext). The second end (3) is defined by a second end plane (S2) and a second inner surface portion (P2¡nt) that extends along a second axial length (Lz) from the second end plane (52) to a second inner transition plane (C¡nt). The second inner transport plane (Cm) passes orthogonally through the first outer surface portion (Plext). In other words, the first outer surface portion (Plext) and the second inner surface portion (P2nt) overlap in the area bounded by the second inner transition plane (Cnt) and the first outer transition plane (Bext). Thus, the first axial length (Li) and the second axial length (L2) are such that their sum is greater than the total axial length (Lt) of the connecting portion (1). This results in excess material and a significant wall thickness (7) in the transition portion (4), particularly in the area defined between the second inner transition plane (Cnt) and the first outer transition plane (Bext) where the portions (Plext) and (P2nt) overlap. To obtain a more homogeneous wall thickness in the transition portion of the connecting part, the geometries of the connecting parts of the prior art are not sufficient, since an excess of material is always present in the transition portion. cu oenn / eznz / E / YiAi Figure 2 shows, as a diagram, a longitudinal cross-sectional view of a connecting part (1) according to one embodiment of the invention. The connecting part (1) comprises a first threaded end (2), a second threaded end (3), and a transition portion (4) connecting the ends (2) and (3). Furthermore, the part (1) comprises a wall (7) bounded by an inner surface (5) and an outer surface (6). The wall (7) includes several portions that can be delimited by end planes and / or transition planes. More specifically, the connecting part (1) shown in Figure 2 includes a first end plane (SI) and a second end plane (S2), a first inner transition plane (Aint) and a second inner transition plane (Cint), a first outer transition plane (Bext) and a second outer transition plane (Dext). The first end (2) has a first inner diameter (IDi) and a first outer diameter (ODi). The first end (2) extends from the first end plane (SI) to the first outer transition plane (Bext). The threading is represented in the figures as a diagram. Typically, the threads at both ends have inclined faces. The first end (2) comprises a first outer surface portion (Plext) extending along a first axial length (Li). The first axial length (Li) is greater than an axial length along which a first inner surface portion (Plint) extends. The first end (2) further has a first unthreaded portion (9) extending along a first unthreaded length (k). The wall (7) of the first end (2) has a first thickness (El) that is substantially constant along the entire first unthreaded length (li). In other words, the first thickness (El) is substantially constant along the entire portion of wall (7) where the first portion of inner surface (Pl¡nt) and the first portion of outer surface (Plext) overlap. The first unthreaded portion (9) is located close to the transition portion (4). In the threaded portion of the first end (2), the initial thickness (El) varies according to the dimension and geometry of the threads. Figure 2 shows an embodiment where the first end (2) has a female thread, i.e., the inner surface (5) is threaded and the outer surface (6) is unthreaded. However, according to the invention, threading can be present on either the inner surface (5) or the outer surface (6) of the first end (2). The threaded portion of the first end (2) is located distal to the transition portion (4). The second end (3) has a second inner diameter (ID2) and a second outer diameter (OD2). The second inner diameter (ID2) is smaller than the first inner diameter (IDi), and the second outer diameter (OD2) is smaller than the first outer diameter (ODi). The second end (3) extends from the second end plane (S2) to the second inner transition plane (C¡nt). The second end (3) comprises a second inner surface portion (Pl¡nt) extending along a second axial length (Lz). The second axial length (Lz) is greater than an axial length along which the second outer surface portion (P2ext) extends. The second end (3) further has a second unthreaded portion (8) extending along a second unthreaded length (lz). The wall (7) of the second end (3) has a second thickness (E2) that is substantially constant along the entire second unthreaded length (lz). In other words, the second thickness (E2) is substantially constant along the entire portion of wall (7) where the second portion of inner surface (P2int) and the second portion of outer surface (P2ext) overlap. The second unthreaded portion (8) is located close to the transition portion (4). In the threaded portion of the second end (3), the second thickness (E2) varies according to the dimension and geometry of the threads. Figure 2 shows an embodiment where the second end (3) has a female thread, i.e., the inner surface (5) is threaded and the outer surface (6) is unthreaded. However, according to the invention, threading can be present on either the inner surface (5) or the outer surface (6) of the second end (3). The threaded portion of the second end (3) is located distal to the transition portion (4). The first and second ends (2) and (3) are shown in Figure 2, both having a female thread; however, the present invention also covers the case where both ends (2) and (3) have a male thread, as well as the case where one of the two ends (2) and (3) has a female thread and the other a male thread. The transition portion (4) extends from the first transition plane (Ant) to the second transition plane (Dext). The connecting part (1) thus comprises two wall portions in which the ends (2) and (3) are aligned with the transition portion (4). These two portions are referred to as connection areas. Each connection area is defined by an inner connection radius and an outer connection radius (not shown in the figures) that gives the connection areas a rounded shape. The radius of curvature of this rounded shape, i.e., the connection radius, can be between, and inclusive of, 20 mm and 80 mm, preferably between, and inclusive of, 25 mm and 65 mm. More preferably, the connection radii measure 50 mm. The connection radii may meet these dimensions to limit the concentration of stresses or forces applied to the transition portion (4) when the connecting part (1) is in operating condition.If they are not properly sized, these stresses may exceed the elastic limit of the connecting part (1). cu oenn / eznz / E / YiAi The first connection area is bounded by the first transition plane (Aint) and the first outer transition plane (Bext), and the second connection area is bounded by the second inner transition plane (Cint) and the second outer transition plane (Dext). The first and second connection areas allow the first and second ends (2) and (3) to gradually connect to the transition portion (4). In the connection areas, only one of the inner and outer diameters of part (1) varies, while the other remains constant. Thus, in the first connection area, only the inner diameter (IDi) varies along a slope with an angle of inclination α to the (x) axis. In the second connection area, only the second outer diameter (OD?) varies along a slope with an angle of inclination α2 to the (x) axis. The portion of the wall (7) with the transition thickness (W) is located between the two connection areas. More specifically, the portion of the wall (7) with the transition thickness (W) extends from the first outer transition plane (Bext) to the second inner transition plane (Cint). In this portion of the wall (7), the inner surface (5) and the outer surface (6) are referred to as the outer transition surface (SText) and the inner transition surface (STint), respectively. In contrast to the connection areas, in this portion of the wall (7) with the transition thickness (W), both the inner and outer diameters vary. The inner diameter varies according to a slope with an angle of inclination α2 to the x-axis. The outer diameter varies according to a slope with an angle of inclination α to the x-axis. The angles α and α2 both have a value between, and inclusive of, 10° and 30°, such that: 10° < α < 30° and 10° < α2 < 30°.The difference in slope between the inner transition surface (ST¡nt) and the outer transition surface (SText) does not exceed 5 degrees and, preferably, does not exceed 2 degrees, so that: |al - a2| < 5°, preferably |al - a2| < 2°.

Claims

1. A tubular metal connecting part (1) having at least one axis of revolution (x) and a total length (Lt), wherein said connecting part (1) comprises: - an inner surface (5) and an outer surface (6), wherein said inner (5) and outer (6) surfaces define a wall (7), - at least one first outer transition plane (Bext) and at least one second outer transition plane (Dext), wherein both of said outer transition planes (Bext) and (Dext) are orthogonal to the axis of revolution (x), - at least one first inner transition plane (Aint) and at least one second inner transition plane (Cint), wherein both of said inner transition planes (Aint) and (Cnt) are orthogonal to the axis of revolution (x), - an outer transition surface (SText) having a truncated conical shape defined by an outer transition generatrix (G) having an inclination of angle to the axis of revolution (x),wherein said outer transition surface (SText) extends from the first outer transition plane (Bext) to the second outer transition plane (Dext), - an inner transition surface (ST¡nt) having a truncated conical shape defined by a transition generatrix (G) having an inclination angle α2 to the axis of revolution (x), wherein said transition surface (ST¡nt) extends from the first inner transition plane (A¡nt) to the second inner transition plane (D¡nt), wherein said transition surface (SText) and said inner transition surface (ST¡nt) delimit a wall transition thickness (W) of the wall (7), - a first male or female threaded end (2), having a first end plane (SI) orthogonal to the axis of revolution (x), a first inner diameter (IDi) and a first outer diameter (ODi),wherein said first end (2) is defined by a first inner surface portion (Plmt) of inner diameter (IDi) extending from the first end plane (SI) to the first transition plane (Aint), and by a first outer surface portion (Plext) of outer diameter (ODi) extending along a first axial length (Li) from the first end plane (SI) to the first outer transmission plane (Bext), wherein said first inner surface portion (Plmt) has a substantially cylindrical shape defined by a first inner surface generatrix (Glmt), and wherein said first outer surface portion (Plext) has a substantially cylindrical shape defined by a first outer surface generatrix (Glext), - a second end (3) male or female threaded, having a second end plane (S2) orthogonal to the axis of revolution (x),a second inner diameter (ID2) and a second outer diameter (OD2), wherein said second end (3) is defined by a second portion of inner surface (P2¡nt) of inner diameter (ID2) and extending along a second axial length (L2) from the second end plane (S2) to the second inner transition plane (C¡nt), and by a second portion of outer surface (P2ext) of outer diameter (OD2) and extending from the second end plane (S2) to the second outer transition plane (Dext), wherein said portion of inner surface (P2¡nt) has a substantially cylindrical shape defined by a second inner surface generatrix (G2¡m), wherein said second portion of outer surface (P2ext) has a substantially cylindrical shape defined by a second outer surface generatrix (G2ext),where the sum of the first and second axial lengths (Li) and (L2) is less than or equal to the total axial length (Lt) of the connecting part (1), where said connecting part (1) is characterized in that the first end (2) has a first wall thickness (El) of the wall (7), where the second end (3) has a second wall thickness (E2) of the wall (7) and the transition thickness (W) satisfies the following equation: [Mathematics] 1 x max (El; E2) < W < 1.5 x max (El; E2) where: max (El; E2) represents the largest selected value of the first and second thicknesses (El) and (E2), and corresponds to (El) and (E2) when (El) and (E2) are equal.

2. The connecting part (1) according to claim 1, further characterized in that the first end (2) has at least a first unthreaded part (9), and the second end (3) has at least a second unthreaded part (8).

3. The connecting part (1) according to claim 2, further characterized in that the first unthreaded part (9) extends along a first unthreaded length (l1) from the first inner transition plane (A1nt), and the second unthreaded part (8) extends along a second unthreaded length (l2) from the second inner transition plane (C1nt). 4,- The connecting part (1) in accordance with any of the preceding claims, further characterized in that the angles a1 and a2 are both between, and including, 10° and 30° with respect to the axis of revolution (x). 5.- The connecting part (1) in accordance with any of the preceding claims, further characterized in that the angles a1 and a2 are such that |α 1 - a2| < 5o, preferably the angles a1 and a2 are such that |a1 - a2| < 2o.

6. The connecting part (1) in accordance with any of the preceding claims, further characterized in that the wall (7) is produced completely or totally by additive manufacturing.

7. A method for obtaining the connecting part (1) in accordance with any of the preceding claims, characterized in that said method comprises at least: i. a step of producing the wall (7) completely or partially by additive manufacturing, ii. a step of machining the first (2) and second ends (3).

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