THREADED CONNECTION FOR HOSE

Abstract

The present invention refers to oil and gas equipment and is applicable to threaded connections for casings, which are used for the construction of vertical wells, directional wells and horizontal wells. The connection comprises a male and a female element, the ends of which, both externally and internally, have been formed in accordance with tapered trapezoidal threads, sealing surfaces, transitions as well as shoulder end faces. The apex and root of the thread turning profile of the male and female elements are formed parallel to the axial line of the thread. The additional surface is formed in the form of a tapered surface on the female element and a tapered surface or a convex spherical surface on the male element. The transition from the sealing surface to the additional surface is formed in the form of a concave spherical surface on the male element and in the form of a convex spherical surface on the female element.High tightness of joints under considerable mechanical loads is achieved by improving the fitting characteristics of the joints, preventing joint jamming at the initial stage of installation, reducing damage (galling) of the surfaces.

Description

Description THREADED CONNECTION FOR SHINGTS Invention Engineering Field The present invention refers to a threaded connection for casings and is applicable to the joining of assembled elements, which are used for the construction of vertical wells, directional wells and horizontal wells in oil, gas, gas-condensate fields. Background of the Invention Casings for oil, gas, and gas condensate wells operate under complex conditions—under significant multidirectional combined mechanical loads (tension, compression, bending, and torsion). Considering the above, the primary requirement for threaded casing connections is to maintain tightness, including gas tightness, at high mechanical load levels. In addition, taking into account the assembly of threaded joints for sleeves in the field, threaded joints must have the characteristics of fast installation and ease of installation and disassembly, reliable alignment, stabilization of threaded joint elements relative to each other, resistance to numerous disassembly and assembly cycles without observed damage to the contact surfaces of the threads, seals and the surface of the pipe shoulder end face. The prior art discloses a threaded connection for a sleeve containing male and female elements, the ends of which, both externally and internally, have been made in accordance with tapered trapezoidal threads, the sealing and shoulder end face surfaces of which form an internal sealing unit. The tapered trapezoidal threads of the male and female elements are made with the apex and root of the thread turning profile parallel to the axial line of the thread. The sealing surfaces on the male and female elements are made in the form of spherical, concave and convex surfaces (RU 2639343 C1, 21.12.2017 (1) The threaded connection for the sleeve disclosed in document (1) does not guarantee the tightness (in particular gas tightness) of the connection under the influence of multi-directional combined mechanical loads. The jamming of the connection at the initial stage of installation, and damage (galling (metal abrasions)) of the threaded connection surface during operation, under the influence of high levels of mechanical loads, which leads to a decrease in the tightness of the connection. This engineering solution (1) is designed to provide the closest example to the claimed invention. Brief Description of the Invention The technical solution provided by the claimed invention, is the maintenance of high tightness of the joint under the influence of sufficient multi-directional mechanical combined loads, such technical result is achieved by improving the installation characteristics of the joint - prevention of joint jamming at the initial stage of installation, and preventing damage (galling) of the sealing surfaces. Threaded connection for a sleeve containing male and female elements, the ends of which, both externally and internally, have been made in accordance with tapered trapezoidal threads, and the sealing and shoulder end face surfaces of which form an internal sealing unit. The tapered trapezoidal threads of the male and female elements are made with the apex and root of the thread turning profile parallel to the axial line of the thread. The internal sealing unit is provided with an additional surface located between the sealing surface and the shoulder end face surface. Additional surfaces are made in the form of tapered surfaces on the female elements and tapered surfaces or convex spherical surfaces on the male elements. The transition from the sealing surface to the additional surface is made in the form of a concave spherical surface on the male element and in the form of a convex spherical surface on the female element. Specifically in the claimed invention design, the trapezoidal threads of the male and female elements are made with a taper of 1:18. Specifically in the claimed invention design, the trapezoidal threads of the male and female elements are made with a taper of 1:12. Specifically in the claimed invention design, the trapezoidal threads of the male and female elements are made with a taper of 1:8. Specifically in the claimed invention design, the threads The tapered trapezoid of male and female elements is made with a slope of 8.467 mm. Specifically in the claimed design of the invention, the trapezoidal tapered threads of the male and female elements are made with a slope of 5.08 mm. Specifically in the claimed design of the invention, the trapezoidal tapered threads of the male and female elements are made with an inclination angle of the thrust flange of the turning profile of 13-170 to the normal line of the thread axis. Specifically in the claimed invention design, the trapezoidal tapered threads of the male and female elements are made with a rotational profile load flange inclination angle of -3 to 70 to the normal line of the thread axis. Specifically in the claimed design of the invention, the shoulder end face surfaces of the male and female elements are made at an angle of 8-120 to the normal line of the thread axis. In particular, in the claimed design of the invention, the sealing surfaces of the male and female elements are tapered with an inclination angle of 11-140 to the normal line of the thread axis. In particular, in the claimed design of the invention, the sealing surface is made in the form of a convex spherical surface with a radius of 125-200 mm on the male element and in the form of a tapered surface with an inclination angle of 11-140 to the normal line of the thread axis on the female element. In particular, in the claimed design of the invention, the transition from the apex to the puncture side of the threaded rotary profile of the male and female elements is made in the form of a complex surface consisting of two spherical surfaces, having different radii. In particular, in the claimed design of the invention, the radius of the spherical surface adjacent to the apex of the threaded turning profile of the male and female elements is equal to 0.2 - 0.5 mm, and the radius of the spherical surface adjacent to the puncture side of the threaded turning profile of the male and female elements is equal to 1.1 - 1.3 mm In particular, in the claimed design of the invention, the additional surface is made in the form of a tapered surface with an inclination angle of 3-60 to the axial line of the thread on the male and female elements. In particular, in the claimed design of the invention, the additional surface is made in the form of a convex spherical surface with a radius of 90-100 mm on the male element and in the form of a tapered surface with an inclination angle of 3-60 to the axial line of the thread on the female element. In particular, in the claimed design of the invention, a concave spherical surface between the sealing surface and the additional surface of the male element is made with a radius of 3-5 mm. In particular, in the claimed design of the invention, a convex spherical surface between the sealing surface and the additional surface of the female element is made with a radius of 6-8 mm. Short Description of Image Figure 1 shows the claimed threaded connection for the installed casing. Figure 2 shows the turning profile of a threaded connection. Figure 3 shows the internal sealing unit. Complete Description of the Invention A threaded connection for a sleeve is claimed to contain a male element (1) and a female element (2) whose ends, both externally and internally, are made to align with each other by means of a tapered trapezoidal thread (3). The thread turning profile (3) is made in the form of an unequal-sided trapezoid, the sides of which are made in the form of a loading side (4) and a piercing side (5), which have different angles of inclination to the normal line of the thread axis. When installing the connection with such threads, the load sides (4) of the threaded rotary profiles (3) of the male element (1) and the female element (2) come into contact with each other and perform axial tensile loads affecting the connection for casing. In other words, the contact of the load sides (4) of the threaded rotary profiles (3) on the male element (1) and the female element (2) prevents thread crossing (thread wear) (3) on the male element (1) and the female element (3) at the limit tensile loads applied to the connection under the string against the load of the well itself. Also achieved reduction of radial interference values ​​on the threads, which provides high wear resistance of the connection, increasing work efficiency at high loads. When assembling a connection with a trapezoidal thread a structural gap appears on the puncture side (5) of the thread turning profile (3), which provides increased fit of the connection allows for multiple disassembly and assembly of the threaded connection without damage (galling) of the thread contact surface (3) and without loss of the performance characteristics of the connection, provides prevention of jamming of the connection at the initial stage of installation. The above is achieved by stabilizing the position of the male (1) and female (2) elements relative to each other at the initial stage of installation. The threads (3) on the male (1) and female (2) elements are made in a tapered shape, which on the one hand provides high biting action during installation and can withstand high bending and tensile loads arising during operation, and on the other hand - maintains the installation characteristics of the connection, as well as prevents thread jamming. The apex (6) and root (7) of the thread turning profile (3) are made parallel to the axial line of the thread, in order to avoid thread jamming at the initial stage of installation, providing a deep free entry path for the male element (1) into the female element (2) during installation, without damage (galling) of the apex (6) and root (7) of the thread turning profile (3). The thread profile (3) described above of the claimed connection provides 100% of its compression efficiency, preventing the connection from jamming, damaging its surface during installation. The claimed invention is made up of an internal sealing unit, which is formed by bringing together sealing surfaces (8), (9) and shoulder end face surfaces (10), (11) on the male (1) and female (2) elements of the connection. The presence of an internal sealing unit in the joint, the seal (8), (9) and the end face surfaces of the shoulders (12), (13) which in the assembled state are connected to each other with sufficient contact stress, with the appearance of elastic strain and the formation of metal-to-metal sealing, provides high tightness of the joint including gas tightness of the joint affected by combined multi-directional mechanical loads in any combination. In addition, the contact surface of the shoulder end surfaces (12), (13) provides contraction and improvement of the sealing surfaces (8), (9), creating the resistance of the connection to compression loads. Accurate positioning of the male element (1) in relation to the female element (2), accurate installation of the design values ​​of the interference and installation torque during installation of the connection - in other words, also provided improved installation characteristics, the possibility of checking the installation of the connection. Additional surfaces (10), (11) are located between the seals (8), (9) and the end face surfaces of the shoulders (12), (13). Additional surfaces (10), (11) are made in the form of tapered surfaces on the female element (2) and tapered surfaces or convex spherical surfaces on the male element (1). During the installation process of the claimed threaded connection, when the threads (3) of the male (1) and female (2) elements interact, the additional surfaces (10), (11) of the male (11) and female (2) elements come into contact with each other and their further interaction (contact) occurs. After that, the sealing surfaces (8), (9) of the male (1) and female (2) elements interact, due to the plastic strain of which a metal-to-metal seal is formed. In addition, in the fully installed state, the additional surfaces (10), (11) of the male (1) and female (2) elements do not come into contact with each other, which forms a gap. Thus, the additional surfaces (10), (11) in the process of fitting the connection, during the transition from the thread contact (3) to the contact of the sealing surfaces (8), (9), bear part of the contact pressure, thereby protecting the sealing surfaces (8), (9), from damage (galling) during fitting the connection. Additional surfaces (10), (11) are made in the form of tapered surfaces on the male (1) and female (2) elements which provide partial relief of contact pressure from the sealing surfaces (8), (9) (to protect the sealing surfaces (8), (9). Additional surfaces (10), (11) are made in the form of tapered surfaces on the female element (2) and convex spherical surfaces on the male element (1) which on the one hand provide an optimal contact area of ​​additional surfaces (10), (11) during the assembly of the connection and the necessary stress level of the contacting additional surfaces (10), (11) which is necessary to release part of the contact stress from the sealing surfaces (8), (9) (to protect the sealing surfaces (8), (9)), on the other hand provide for optimal soft and smooth dismantling of the additional surfaces (10), (11) after contact, without damage (galing) of the additional surfaces (10), (11). In addition, the application of the sealing surfaces (8), (9) at a distance from the end face surfaces of the shoulders (12), (13), that is, the removal of the contact area of ​​the sealing surfaces (8), (9) from the contact area of ​​the end face surfaces of the shoulders (12), (13), leads to a reduction in the interdependence of the sealing surfaces (8), (9) and the end face surfaces of the shoulders (12), (13) and ensures maximum tightness of the connection at any combination of loads, including gas tightness. The transition from the sealing surfaces (8), (9) with the additional surfaces (10), (11) is made in the form of a concave spherical surface (14) on the male element (1) and in the form of a convex spherical surface (15) on the female element (2). During the installation process of the claimed threaded connection, after the interaction of the threads (3) of the male (1) and female (2) elements, the sealing surfaces (8), (9) pass relative to each other, which begins with the interaction of the transition surfaces - the convex spherical surface (14) on the male element (1) and the convex spherical surface (15) on the female element (2). The application of the transition surfaces (14), (15) as described above facilitates the passage of the sealing surfaces (8), (9) relative to each other at the moment of the first contact, ensures the safety of the sealing surfaces (8), (9), protects against damage (galling) during the installation of the connection. In addition, the convex spherical surface (15) on the female element (2) increases the contact area of ​​the sealing surfaces (8), (9) of the male (1) and female (2) elements, which positively affects the tightness of the connection. Examples of Application of Invention: The claimed threaded connection for the sleeve functions as follows. After the alignment of the male elements (1) and female elements (2) with each other, the initial step in the installation process is to engage the male elements (1) and female elements (2) using a tapered trapezoidal thread (3), which is made on the outer surface of the male element and the inner surface of the female element (2). There is further extension of the additional surfaces (10), (11) of the male elements (1) and female elements (2) related to each other and their connection (contact). After that the transition surfaces (14), (15) and sealing surfaces (8), (9) of the male (1) and female (2) elements interact, due to the plastic strain of which a metal-to-metal seal is formed. The specified transition from the contact of the additional surfaces (10), (11) to the contact of the sealing surfaces (8), (9) shown on the connection installation diagram as a transition segment, is a form of jump towards reducing the installation torque and its further increase. The completion of the joint installation process is carried out by means of contact force on the surface of the shoulder end faces (12), (13), which are formed on the male elements (1) and female elements (2) which causes contact pressure from the surface of the shoulder end faces (12), (13), the value of which is in the elastic stress range. Additional surfaces (10), (11) in the assembled state of the male (1) and female (2) elements do not touch each other, which forms a gap. Examples of embodiments of the invention: To perform the test of the claimed threaded connection for the sleeve, samples were made (Number 1, 2, 3). For example, No. 1, a sleeve with a diameter of 178 mm is used as a blank connection. On the outer surface of the male element and the inner surface of the female element of this example, a tapered trapezoidal thread with a taper of 1:12, with a slope of 8.467 mm, with a slope angle of the thrust side turning profile of 150 and a slope angle of the load side turning profile of -50 to the normal line of the thread axis. The peak and root of the thread turning profile of the male and female elements are made parallel to the axial line of the thread. The internal sealing unit element is formed, then the sealing surface is made in the form of a convex spherical surface with a radius of 125 mm on the male element and a tapered surface with a slope angle of 120 to the thread axial line on the female element, the additional surface is generated in the form of a convex spherical surface with a radius of 90 mm on the male element and a tapered surface with a slope angle of 40 to the thread axial line on the female element, the shoulder end face surface is generated at an angle of 100 to the thread normal axis line. The transition from the sealing surface to the additional surface is made in the form of a concave spherical surface with a radius of 3 mm on the male element and in the form of a convex spherical surface with a radius of 7 mm on the female element. For example No. 2, a sleeve with a nominal diameter of 114 mm is used as a blank connection. On the outer surface of the male element and the inner surface of the female element of example No. 2, a tapered trapezoidal thread with a taper of 1:18, with a slope of 5.08 mm, with a slope angle of the thrust side turning profile of 150 and a slope angle of the load side turning profile of -50 to the normal line of the thread axis. The peak and root of the thread turning profile of the male and female elements are made parallel to the axial line of the thread. The elements of the internal sealing unit are formed: the sealing surfaces are made tapered with an angle of inclination of 120 to the axial line of the thread; the surfaces of the shoulder end faces are formed with an angle of 100 to the normal axis line of the thread; the additional surfaces are made tapered with an angle of inclination of 40 to the normal axis line of the thread. The transition from the sealing surfaces to the additional surfaces is made in the form of a concave spherical surface with a radius of 5 mm on the male element and in the form of a convex spherical surface with a radius of 7 mm on the female element. In addition, a specimen (No. 3) was manufactured, which had the closest analogous geometric parameters - a casing with a nominal diameter of 178 mm as a blank connection was used. On the outer surface of the male element and the inner surface of the female element of sample item No. 3, a tapered trapezoidal thread with a taper of 1:16 is formed, with a slope of 6.35 mm, with a slope angle of the thrust side turning profile of 150 and a slope angle of the load side turning profile of -50 to the normal line of the thread axis. The internal sealing unit element is formed: the sealing surface is produced in a spherical shape; the end face surface of the shoulder is formed at an angle of 100 to the normal axis line of the thread. Sample testing for installation / disassembly is carried out until damage occurs to the threaded surfaces and internal seal assembly. Testing of the above-mentioned samples showed the appearance of surface damage (galling) after two cycles of disassembly and assembly of the sample No. 3 made in accordance with the prior art, and the absence of joint jamming and damage (galling) on ​​the surface after five cycles of disassembly and assembly of the specimens No. 1, 2 made in accordance with the claimed invention. The use of the proposed threaded connection ensures the durability of the connection tightness bearing a 20% increase in the combined multi-directional mechanical load value.

Claims

Claim 1. A threaded connection for a casing comprising a male and a female element, the ends of which, both externally and internally, are made interlocking with a tapered trapezoidal thread, and the sealing and the shoulder end face surfaces forming an internal sealing unit, the apex and the root of the thread rotation profiles of the male and female elements being produced parallel to the thread axis line, characterized in that an internal sealing unit is provided with an additional surface, located between the sealing surface and the shoulder end face surface, at this time, the additional surface is made in the form of a tapered surface on the female element and a tapered surface or a convex spherical surface on the male element and the transition from the sealing surface to the additional surface is made in the form of a concave spherical surface on the male element and a convex spherical surface on the female element.

2. The connection according to claim 1, wherein the trapezoidal threads of the male and female elements are formed with a taper of 1:

18.

3. The connection according to claim 1, wherein the trapezoidal threads of the male and female elements are formed with a taper of 1:

12.

4. The connection according to claim 1, wherein the trapezoidal threads of the male and female elements are formed with a taper of 1:

18.

5. The connection according to claim 1, wherein the tapered trapezoidal threads of the male and female elements are formed with a pitch of 8.467 mm.

6. The connection according to claim 1, wherein the tapered trapezoidal threads of the male and female elements are formed with a pitch of 5.08 mm.

7. The connection according to claim 1, wherein the trapezoidal tapered threads of the male and female elements are made with an inclination angle of the turning profile thread flange of 13-170 to the normal line of the thread axis.

8. The connection according to claim 1, wherein the trapezoidal tapered threads of the male and female elements are made with an inclination angle of the load side of the rotating profile of -3 go -70 to the normal line of the thread axis.

9. The connection according to claim 1, wherein the shoulder end surfaces of the male and female elements are made at an angle of 8-120 to the normal axis of the thread.

10. The connection according to claim 1, wherein the sealing surfaces of the male and female elements are tapered at an angle of 11-140 to the thread axis line.

11. The connection according to claim 1, wherein the sealing surface is made in the form of a convex spherical surface with a radius of 125-200 mm on the male element and in the form of a tapered surface with an inclination angle of 11-140 to the normal line of the thread axis on the female element.

12. The connection according to claim 1, wherein the transition from the apex to the puncture side of the threaded turning profile of the male and female elements is made in the form of a complex surface consisting of two spherical surfaces, having different radii.

13. The connection according to claim 12, wherein the radius of the spherical surface adjacent to the top of the threaded turning profile of the male and female elements is made equal to 0.2 - 0.5 mm, and the radius of the spherical surface adjacent to the insert side of the threaded turning profile of the male and female elements is made equal to 1.1 - 1.3 mm 14. The connection according to claim 1, wherein the additional surface is made in the form of a tapered surface with an inclination angle of 3-60 to the thread axis line on the male and female elements.

15. The connection according to claim 1, wherein the additional surface is made in the form of a convex spherical surface with a radius of 90-100 mm on the male element and in the form of a tapered surface with an inclination angle of 3-60 to the thread axis line on the female element.

16. The connection according to claim 1, wherein the concave spherical surface between the sealing surface and the additional surface of the male element is made with a radius of 3-5 mm.

17. The connection according to claim 1, wherein a concave spherical surface between the sealing surface and the additional surface of the female element is formed with a radius of 6-8 mm.

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