Threaded joint for oil and gas pipeline

Abstract

The invention discloses an oil and gas pipeline screwed joint which comprises an outer screwed joint and an inner screwed joint which are hollow and tubular and are arranged in a matched mode, and further comprises a first main sealing structure, a first auxiliary sealing structure, an inner thread, an outer thread, a second auxiliary sealing structure and a second main sealing structure which are sequentially arranged in the axial direction. An oil and gas pipeline threaded connector solves the problem that in the prior art, sealing performance is insufficient, and aiming at the characteristic that glass fiber reinforced plastic materials are poor in toughness, four-stage sealing structures are arranged on the connector and include the first main sealing structure, the second main sealing structure, the first auxiliary sealing structure and the second auxiliary sealing structure. And elastic sealing parts and materials are introduced into each stage of sealing structure, so that the excellent air-tight sealing performance is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of pipeline auxiliary equipment and relates to an oil and gas pipeline threaded joint device. Background Art

[0002] With the continuous development of oil and gas resources, most oilfields have entered the middle and late stages of development. As the main carrier of oil and gas transportation, the service environment faced by oil and gas gathering and transportation pipelines is becoming increasingly harsh. On the one hand, with the continuous increase in the water cut of crude oil, the high salinity formation water causes serious scaling on the inner wall of the pipeline, and the number of pipeline corrosion perforation and leakage accidents caused by under-deposit corrosion is increasing continuously; on the other hand, the produced oil and gas also face corrosion from media such as high sulfur, carbon dioxide, and chloride ions, which also increases the risk of corrosion perforation inside the pipeline to a certain extent. Through long-term research on the internal corrosion mechanism and prevention measures of gathering and transportation pipelines, it is found that fiberglass pipelines have a wide application prospect in the high-corrosion working conditions of oil and gas fields due to their strong corrosion resistance.

[0003] Fiberglass pipeline is a non-metallic pipeline made of resin, glass fiber, and quartz sand by a special process. It has the characteristics of strong corrosion resistance, good hydraulic characteristics, light weight and high specific strength, non-pollution of the transported medium, fast installation, and easy-to-master construction methods. In recent years, fiberglass pipelines have been widely used in oil and gas field surface engineering at home and abroad, especially in the Middle East, the Gulf region, Jilin Oilfield, and Tarim Oilfield in China.

[0004] The selection of the connection method and location for fiberglass pipes is generally determined through consultation between the design and pipe manufacturers based on the usage requirements proposed by the owner and the project characteristics. The common connection forms include: socket adhesion, butt wrapping connection, socket connection with or without a locking structure using a sealing ring, flange connection, and threaded connection. Among them, threaded connection is widely used due to its economic efficiency in processing and manufacturing and the convenience of on-site installation and construction. Currently, the threaded structures used in oil and gas transportation pipelines all adopt the round thread or the buttress thread specified in API. This threaded structure poses a risk of leakage during the service life of the pipeline, mainly for the following reasons: Firstly, the threads in API are designed based on the properties of steel materials and are not suitable for fiberglass materials. Since steel materials are isotropic, that is, the mechanical properties of the material are exactly the same in all directions. While fiberglass sleeves are composed of resin, glass fibers, and quartz sand, and the material is anisotropic, that is, the mechanical properties in the axial, radial, and circumferential directions are completely inconsistent, which leads to completely inconsistent meshing degrees of the threads in these three directions. Secondly, since the API threads themselves do not have sealing ability, the realization of their sealing performance mainly depends on the thread compound applied to the thread surface to fill the space between the inner and outer thread flanks after thread meshing. This is very effective for liquid sealing, but oil and gas pipelines often transport a mixture of oil and gas, which easily causes gas leakage. As the pressure of the transported medium inside the pipe and the pipe diameter continue to increase, the risk of leakage of the medium inside the pipe from the threaded joint also continues to increase.

[0005] In summary, for the connection of fiberglass oil and gas transportation pipelines, there is a problem of insufficient sealing performance in the existing technology. Summary of the Invention

[0006] The purpose of the present invention is to provide a threaded joint for oil and gas pipelines, which solves the problem of insufficient sealing performance in the existing technology.

[0007] The technical solution adopted by the present invention is that a threaded joint for oil and gas pipelines includes a hollow tubular outer threaded joint and an inner threaded joint that are cooperatively arranged, and further includes a first main sealing structure, a first auxiliary sealing structure, an inner thread, an outer thread, a second auxiliary sealing structure, and a second main sealing structure that are sequentially arranged along the axial direction.

[0008] The characteristics of the present invention also lie in:

[0009] The interference of the pitch diameters of the outer threaded joint and the inner threaded joint is 0.38 mm - 0.51 mm, the taper of the outer threaded joint and the inner threaded joint is 1:10, the pitch is 6.34 mm - 6.36 mm, and the materials of the outer threaded joint and the inner threaded joint are fiberglass.

[0010] The external thread joint includes a first main shoulder, a first sealing groove, a second sealing groove, an external thread, a fourth sealing groove, a third sealing groove, and a first auxiliary shoulder arranged axially in sequence; the internal thread joint includes a second auxiliary shoulder, an internal thread auxiliary sealing surface, an internal thread, an internal thread main sealing surface, and a second main shoulder arranged axially in sequence.

[0011] The first main sealing structure includes the second main shoulder. An elastomer of the second main shoulder is fixedly connected to the second main shoulder along the axial direction of the pipeline. The elastomer of the second main shoulder is in close contact with the elastomer of the first main shoulder. The structures of the elastomer of the second main shoulder and the elastomer of the first main shoulder are in the shape of a circular ring with a rhombic cross-section, and the inner angle of the rhombic cross-section is 29.5° - 30.5°. The elastomer of the first main shoulder is fixedly connected to the first main shoulder along the axial direction of the pipeline. The radial length of the elastomer of the second main shoulder is the same as the side length of the cross-section of the second main shoulder. The radial length of the elastomer of the first main shoulder is the same as the side length of the cross-section of the first main shoulder. The materials of the elastomer of the second main shoulder and the elastomer of the first main shoulder are rubber.

[0012] The first auxiliary sealing structure includes the first sealing groove and the second sealing groove. The structures of the first sealing groove and the second sealing groove are in the shape of annular grooves and are arranged in parallel on the inner wall of the external thread joint. The first sealing groove is filled with a first non-metallic elastic sealing ring, and the second sealing groove is filled with a second non-metallic elastic sealing ring. The first non-metallic elastic sealing ring and the second non-metallic elastic sealing ring are in interference contact with the internal thread main sealing surface. The materials of the first non-metallic elastic sealing ring and the second non-metallic elastic sealing ring are rubber and Teflon with a compression elastic modulus of 29.5° - 30.5°.

[0013] The second auxiliary sealing structure includes the third sealing groove and the fourth sealing groove. The third sealing groove and the fourth sealing groove are in the shape of annular grooves and are arranged in parallel on the inner wall of the external thread joint. The third sealing groove is filled with a third non-metallic elastic sealing ring, and the fourth sealing groove is filled with a fourth non-metallic elastic sealing ring. The third non-metallic elastic sealing ring and the fourth non-metallic elastic sealing ring are in interference contact with the internal thread auxiliary sealing surface. The materials of the third non-metallic elastic sealing ring and the fourth non-metallic elastic sealing ring are rubber and Teflon with a compression elastic modulus of 400 GPa - 500 GPa.

[0014] The second main sealing structure includes the first auxiliary shoulder. An elastomer of the first auxiliary shoulder is fixedly connected to the first auxiliary shoulder along the axial direction of the pipeline. The elastomer of the first auxiliary shoulder is in close contact with the elastomer of the second auxiliary shoulder. The structures of the elastomer of the first auxiliary shoulder and the elastomer of the second auxiliary shoulder are in the shape of a circular ring with a rectangular cross-section. The elastomer of the second auxiliary shoulder is fixedly connected to the second auxiliary shoulder along the axial direction. The radial length of the cross-section of the elastomer of the first auxiliary shoulder is the same as the side length of the cross-section of the first auxiliary shoulder. The radial length of the cross-section of the elastomer of the second auxiliary shoulder is the same as the side length of the cross-section of the second auxiliary shoulder. The materials of the elastomer of the first auxiliary shoulder and the elastomer of the second auxiliary shoulder are rubber.

[0015] The external thread structure is in the form of a number of annular grooves evenly distributed in parallel. The external thread includes an external thread tooth bottom surface provided at the bottom of the groove. The external thread tooth bottom surface is connected to an external thread advancing surface provided on the groove wall through a first transition arc. The external thread tooth bottom surface is connected to an external thread loading surface provided on the other groove wall through a fourth transition arc. The external thread advancing surface is connected to an external thread tooth top surface through a second transition arc. The external thread tooth top surface and the external thread loading surface are connected through a third transition arc. The arc radii of the second transition arc and the third transition arc are both 0.35 mm - 0.45 mm, and the arc radii of the first transition arc and the fourth transition arc are both 0.45 mm - 0.55 mm. The flank angle of the external thread advancing surface is 16.5° - 17.5°, and the flank angle of the external thread loading surface is 21.5° - 22.5°.

[0016] The internal thread structure is in the form of a number of annular grooves evenly distributed in parallel. The internal thread is arranged in cooperation with the external thread. The internal thread includes an internal thread tooth bottom surface provided at the bottom of the groove. The internal thread tooth bottom surface is connected to an internal thread advancing surface provided on the groove wall through a fifth transition arc. The internal thread tooth bottom surface is connected to an internal thread loading surface provided on the other groove wall through an eighth transition arc. The internal thread loading surface is connected to an internal thread tooth top surface through a seventh transition arc. The internal thread tooth top surface and the internal thread advancing surface are connected through a sixth transition arc. The arc radii of the sixth transition arc and the seventh transition arc are both 0.35 mm - 0.45 mm, and the arc radii of the fifth transition arc and the eighth transition arc are both 0.45 mm - 0.55 mm. The flank angle of the internal thread advancing surface is 16.5° - 17.5°, and the flank angle of the internal thread loading surface is 21.5° - 22.5°.

[0017] The beneficial effects of the present invention are as follows: In the internal and external threads of the threaded joint of the oil and gas pipeline of the present invention, a double shoulder structure of a main shoulder and a secondary shoulder is provided, which effectively improves the stress distribution of the threads after make-up, makes the stress distribution of each thread tooth more uniform, and avoids the galling problem caused by large stress concentration of individual thread teeth. The double positive angle thread profile is introduced, which effectively realizes quick make-up on site and is not prone to cross-threading. The pitch diameter interference amount and the tolerance range are set, which further ensure the reasonable interference amount of each stage of sealing contact after make-up and guarantee the sealing ability. Brief Description of the Drawings

[0018] Figure 1 is a schematic structural diagram of the threaded joint of the oil and gas pipeline of the present invention;

[0019] Figure 2 is a schematic diagram of the first main sealing structure and the first auxiliary sealing structure in the threaded joint of the oil and gas pipeline of the present invention;

[0020] Figure 3 is a schematic diagram of the second main sealing structure and the second auxiliary sealing structure in the threaded joint of the oil and gas pipeline of the present invention.

[0021] Figure 4 This is a schematic structural diagram of the external thread in the threaded joint of the oil and gas pipeline of the present invention;

[0022] Figure 5 This is a schematic structural diagram of the internal thread in the threaded joint of the oil and gas pipeline of the present invention.

[0023] In the figure, 1. External thread joint; 2. Internal thread joint; 3. External thread; 4. Internal thread; 5. First main sealing structure; 6. First auxiliary sealing structure; 7. Second auxiliary sealing structure; 8. Second main sealing structure; 9. Inner wall of external thread; 10. First main shoulder; 11. First main shoulder elastomer; 12. First non-metallic elastic sealing ring; 13. Second non-metallic elastic sealing ring; 14. First sealing groove; 15. Second sealing groove; 16. Main sealing surface of internal thread; 17. Second main shoulder; 18. Inner wall of internal thread joint; 19. Second main shoulder elastomer; 20. Outer wall of external thread joint; 21. First secondary shoulder; 22. First secondary shoulder elastomer; 23. Secondary sealing surface of internal thread; 24. Third sealing groove; 25. Fourth sealing groove; 26. Third non-metallic elastic sealing ring; 27. Fourth non-metallic elastic sealing ring; 28. Second secondary shoulder elastomer; 29. Second secondary shoulder; 30. Outer wall of internal thread joint; 31. Bottom surface of external thread tooth; 32. First transition arc; 33. Thread entry surface of external thread; 34. Second transition arc; 35. Top surface of external thread tooth; 36. Third transition arc; 37. Load-bearing surface of external thread; 38. Fourth transition arc; 39. Bottom surface of internal thread tooth; 40. Fifth transition arc; 41. Thread entry surface of internal thread; 42. Sixth transition arc; 43. Top surface of internal thread tooth; 44. Seventh transition arc; 45. Load-bearing surface of internal thread; 46. Eighth transition arc. Detailed implementation manners

[0024] The present invention will be described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0025] The threaded joint of the oil and gas pipeline of the present invention has a direct connection structure, including as Figure 1The hollow tubular and cooperatively arranged external thread joint 1 and internal thread joint 2 made of fiberglass, the interference of the pitch diameters of the external thread joint 1 and the internal thread joint 2 is 0.38 mm - 0.51 mm, the taper of the external thread joint 1 and the internal thread joint 2 is 1:10, and the pitch is 6.34 mm - 6.36 mm. It also includes a first main sealing structure 5, a first auxiliary sealing structure 6, an internal thread 4, an external thread 3, a second auxiliary sealing structure 7, and a second main sealing structure 8 arranged in sequence along the axial direction. The external thread joint 1 includes a first main shoulder 10, a first sealing groove 14, a second sealing groove 15, an external thread 3, a fourth sealing groove 25, a third sealing groove 24, and a first auxiliary shoulder 21 arranged in sequence along the axial direction; the internal thread joint 2 includes a second auxiliary shoulder 29, an internal thread auxiliary sealing surface 23, an internal thread 4, an internal thread main sealing surface 16, and a second main shoulder 17 arranged in sequence along the axial direction.

[0026] The first main sealing structure 5 includes Figure 2 the second main shoulder 17 as shown. The second main shoulder 17 is fixedly connected with a second main shoulder elastomer 19 along the axial direction of the pipeline. The second main shoulder elastomer 19 is in close contact with the first main shoulder elastomer 11. The structures of the second main shoulder elastomer 19 and the first main shoulder elastomer 11 are circular rings with a rhombus cross-section, and the inner angles of the rhombus cross-section are 29.5° - 30.5°. The first main shoulder elastomer 11 is fixedly connected to the first main shoulder 10 along the axial direction of the pipeline. The radial length of the second main shoulder elastomer 19 is the same as the side length of the cross-section of the second main shoulder 17, and the radial length of the first main shoulder elastomer 11 is the same as the side length of the cross-section of the first main shoulder 10. The materials of the second main shoulder elastomer 19 and the first main shoulder elastomer 11 are rubber. The first auxiliary sealing structure 6 includes Figure 2 the first sealing groove 14 and the second sealing groove 15 as shown. The first sealing groove 14 and the second sealing groove 15 are in the shape of annular grooves and are arranged in parallel on the inner wall of the external thread joint 1. The first sealing groove 14 is filled with a first non-metallic elastic sealing ring 12, and the second sealing groove 15 is filled with a second non-metallic elastic sealing ring 13. The first non-metallic elastic sealing ring 12 and the second non-metallic elastic sealing ring 13 are in interference contact with the internal thread main sealing surface 16. The materials of the first non-metallic elastic sealing ring 12 and the second non-metallic elastic sealing ring 13 are rubber and Teflon with a compression elastic modulus of 400 GPa - 500 GPa.

[0027] The second main sealing structure 8 includes Figure 3The first secondary shoulder 21 shown, a first secondary shoulder elastomer 22 is fixedly connected along the axial direction of the pipeline to the first secondary shoulder 21. The first secondary shoulder elastomer 22 is in close contact with the second secondary shoulder elastomer 28. The structures of the first secondary shoulder elastomer 22 and the second secondary shoulder elastomer 28 are in the shape of an annular ring with a rectangular cross-section. A second secondary shoulder 29 is fixedly connected along the axial direction to the second secondary shoulder elastomer 28. The radial length of the cross-section of the first secondary shoulder elastomer 22 is the same as the side length of the cross-section of the first secondary shoulder 21. The radial length of the cross-section of the second secondary shoulder elastomer 28 is the same as the side length of the cross-section of the second secondary shoulder 29. The materials of the first secondary shoulder elastomer 22 and the second secondary shoulder elastomer 28 are rubber. The second auxiliary sealing structure 7 includes as Figure 3 shown a third sealing groove 24 and a fourth sealing groove 25. The third sealing groove 24 and the fourth sealing groove 25 are in the shape of annular grooves and are arranged in parallel on the inner wall of the external thread joint 1. A third non-metallic elastic sealing ring 26 is filled in the third sealing groove 24. A fourth non-metallic elastic sealing ring 27 is filled in the fourth sealing groove 25. The third non-metallic elastic sealing ring 26 and the fourth non-metallic elastic sealing ring 27 are in interference contact with an internal thread secondary sealing surface 23. The materials of the third non-metallic elastic sealing ring 26 and the fourth non-metallic elastic sealing ring 27 are rubber and Teflon with a compression elastic modulus of 400 GPa - 500 GPa.

[0028] The external thread 3 structure is in the shape of a number of annular grooves arranged in parallel and evenly distributed. The external thread 3 includes as Figure 4 shown an external thread tooth bottom surface 31 provided at the bottom of the groove. The external thread tooth bottom surface 31 is connected by a first transition arc 32 to an external thread advancing surface 33 provided on the groove wall. The external thread tooth bottom surface 31 is connected by a fourth transition arc 38 to an external thread loading surface 37 provided on the other groove wall. The external thread advancing surface 33 is connected by a second transition arc 34 to an external thread tooth top surface 35. The external thread tooth top surface 35 and the external thread loading surface 37 are connected by a third transition arc 36. The arc radii of the second transition arc 34 and the third transition arc 36 are both 0.35 mm - 0.45 mm. The arc radii of the first transition arc 32 and the fourth transition arc 38 are both 0.45 mm - 0.55 mm. The flank angle of the external thread advancing surface 33 is 16.5° - 17.5°. The flank angle of the external thread loading surface 37 is 21.5° - 22.5°.

[0029] The internal thread 4 structure is in the shape of a number of annular grooves arranged in parallel and evenly distributed. The internal thread 4 is arranged in cooperation with the external thread 3. The internal thread 4 includes as Figure 5The inner-thread tooth bottom surface 39 provided at the bottom of the groove is connected to the inner-thread advancing surface 41 provided on the groove wall through a fifth transition arc 40. The inner-thread tooth bottom surface 39 is connected to the inner-thread loaded surface 45 provided on the other groove wall through an eighth transition arc 46. The inner-thread loaded surface 45 is connected to the inner-thread tooth top surface 43 through a seventh transition arc 44. The inner-thread tooth top surface 43 and the inner-thread advancing surface 41 are connected through a sixth transition arc 42. The arc radii of the sixth transition arc 42 and the seventh transition arc 44 are both 0.35 mm - 0.45 mm, and the arc radii of the fifth transition arc 40 and the eighth transition arc 46 are both 0.45 mm - 0.55 mm. The flank angle of the inner-thread advancing surface 41 is 16.5° - 17.5°, and the flank angle of the inner-thread loaded surface 45 is 21.5° - 22.5°.

[0030] In view of the problem of insufficient sealing performance in the prior art, the present invention provides a four-stage sealing structure, namely a first main sealing structure 5, a second main sealing structure 8, a first auxiliary sealing structure 6, and a second auxiliary sealing structure 7. Elastic sealing components and materials are introduced in each stage of the sealing structure, thus ensuring excellent gas sealing performance of the threaded joint of the oil and gas pipeline. A double shoulder structure with a main shoulder and a secondary shoulder is provided in both the internal and external threads, effectively improving the stress distribution of the threads after make-up, making the stress distribution of each thread tooth more uniform, and avoiding the galling problem caused by large stress concentration of individual thread teeth. A double positive angle thread profile is introduced, effectively realizing rapid on-site make-up and not prone to cross-threading. The medium diameter interference and its tolerance range are specified, further ensuring the reasonable interference of each stage of sealing contact after make-up, guaranteeing the sealing ability, and specifically solving the problem of insufficient sealing performance in the prior art.

[0031] Example 1

[0032] As Figures 1 - 5 shown, this example provides a threaded joint for an oil and gas pipeline, which includes a hollow tubular external thread joint 1 and an internal thread joint 2 that are cooperatively arranged, and also includes a first main sealing structure 5, a first auxiliary sealing structure 6, an internal thread 4, an external thread 3, a second auxiliary sealing structure 7, and a second main sealing structure 8 arranged in sequence along the axial direction. The medium diameter interference between the external thread joint 1 and the internal thread joint 2 is 0.38 mm - 0.51 mm. The taper of the external thread joint 1 and the internal thread joint 2 is 1:10, and the pitch is 6.35 mm. The materials of the external thread joint 1 and the internal thread joint 2 are fiberglass.

[0033] Example 2

[0034] As Figures 1 - 5As shown in the figure, this embodiment provides a threaded joint for oil and gas pipelines, which includes a hollow tubular outer threaded joint 1 and an inner threaded joint 2 that are arranged in cooperation, and also includes a first main sealing structure 5, a first auxiliary sealing structure 6, an inner thread 4, an outer thread 3, a second auxiliary sealing structure 7, and a second main sealing structure 8 that are arranged in sequence along the axial direction. The interference of the pitch diameter between the outer threaded joint 1 and the inner threaded joint 2 is 0.38 mm - 0.51 mm, the taper of the outer threaded joint 1 and the inner threaded joint 2 is 1:10, the pitch is 6.35 mm, and the materials of the outer threaded joint 1 and the inner threaded joint 2 are fiberglass. The outer threaded joint 1 includes a first main shoulder 10, a first sealing groove 14, a second sealing groove 15, an outer thread 3, a fourth sealing groove 25, a third sealing groove 24, and a first auxiliary shoulder 21 that are arranged in sequence along the axial direction; the inner threaded joint 2 includes a second auxiliary shoulder 29, an inner thread auxiliary sealing surface 23, an inner thread 4, an inner thread main sealing surface 16, and a second main shoulder 17 that are arranged in sequence along the axial direction.

[0035] The first main sealing structure 5 includes a second main shoulder 17. A second main shoulder elastomer 19 is fixedly connected to the second main shoulder 17 along the axial direction of the pipeline. The second main shoulder elastomer 19 is in close fit with the first main shoulder elastomer 11. The structures of the second main shoulder elastomer 19 and the first main shoulder elastomer 11 are circular rings with a rhombus cross-section, and the inner angle of the rhombus cross-section is 30°. The first main shoulder elastomer 11 is fixedly connected to the first main shoulder 10 along the axial direction of the pipeline. The radial length of the second main shoulder elastomer 19 is the same as the side length of the cross-section of the second main shoulder 17, and the radial length of the first main shoulder elastomer 11 is the same as the side length of the cross-section of the first main shoulder 10. The materials of the second main shoulder elastomer 19 and the first main shoulder elastomer 11 are rubber.

[0036] Embodiment 3

[0037] As Figures 1 - 5 As shown in the figure, this embodiment provides a threaded joint for oil and gas pipelines, which includes a hollow tubular outer threaded joint 1 and an inner threaded joint 2 that are arranged in cooperation, and also includes a first main sealing structure 5, a first auxiliary sealing structure 6, an inner thread 4, an outer thread 3, a second auxiliary sealing structure 7, and a second main sealing structure 8 that are arranged in sequence along the axial direction. The interference of the pitch diameter between the outer threaded joint 1 and the inner threaded joint 2 is 0.38 mm - 0.51 mm, the taper of the outer threaded joint 1 and the inner threaded joint 2 is 1:10, the pitch is 6.35 mm, and the materials of the outer threaded joint 1 and the inner threaded joint 2 are fiberglass. The outer threaded joint 1 includes a first main shoulder 10, a first sealing groove 14, a second sealing groove 15, an outer thread 3, a fourth sealing groove 25, a third sealing groove 24, and a first auxiliary shoulder 21 that are arranged in sequence along the axial direction; the inner threaded joint 2 includes a second auxiliary shoulder 29, an inner thread auxiliary sealing surface 23, an inner thread 4, an inner thread main sealing surface 16, and a second main shoulder 17 that are arranged in sequence along the axial direction.

[0038] The first main sealing structure 5 includes a second main shoulder 17. Axially along the pipeline, a second main shoulder elastomer 19 is fixedly connected to the second main shoulder 17. The second main shoulder elastomer 19 is in close contact with the first main shoulder elastomer 11. The structures of the second main shoulder elastomer 19 and the first main shoulder elastomer 11 are circular rings with a rhombus cross-section, and the inner angle of the rhombus cross-section is 30°. The first main shoulder elastomer 11 is axially fixedly connected to the first main shoulder 10 along the pipeline. The radial length of the second main shoulder elastomer 19 is the same as the side length of the cross-section of the second main shoulder 17, and the radial length of the first main shoulder elastomer 11 is the same as the side length of the cross-section of the first main shoulder 10. The materials of the second main shoulder elastomer 19 and the first main shoulder elastomer 11 are rubber. The first auxiliary sealing structure 6 includes a first sealing groove 14 and a second sealing groove 15. The structures of the first sealing groove 14 and the second sealing groove 15 are annular grooves and are arranged in parallel on the inner wall of the external thread joint 1. A first non-metallic elastic sealing ring 12 is filled in the first sealing groove 14, and a second non-metallic elastic sealing ring 13 is filled in the second sealing groove 15. The first non-metallic elastic sealing ring 12 and the second non-metallic elastic sealing ring 13 are in interference contact with the internal thread main sealing surface 16. The materials of the first non-metallic elastic sealing ring 12 and the second non-metallic elastic sealing ring 13 are rubber and Teflon with a compression elastic modulus of 450 GPa.

[0039] The second auxiliary sealing structure 7 includes a third sealing groove 24 and a fourth sealing groove 25. The third sealing groove 24 and the fourth sealing groove 25 are in the shape of annular grooves and are arranged in parallel on the inner wall of the external thread joint 1. A third non-metallic elastic sealing ring 26 is filled in the third sealing groove 24, and a fourth non-metallic elastic sealing ring 27 is filled in the fourth sealing groove 25. The third non-metallic elastic sealing ring 26 and the fourth non-metallic elastic sealing ring 27 are in interference contact with the internal thread secondary sealing surface 23. The materials of the third non-metallic elastic sealing ring 26 and the fourth non-metallic elastic sealing ring 27 are rubber and Teflon with a compression elastic modulus of 450 GPa. The second main sealing structure 8 includes a first secondary shoulder 21. Axially along the pipeline, a first secondary shoulder elastomer 22 is fixedly connected to the first secondary shoulder 21. The first secondary shoulder elastomer 22 is in close contact with the second secondary shoulder elastomer 28. The structures of the first secondary shoulder elastomer 22 and the second secondary shoulder elastomer 28 are circular rings with a rectangular cross-section. Axially, the second secondary shoulder elastomer 28 is fixedly connected to a second secondary shoulder 29. The radial length of the cross-section of the first secondary shoulder elastomer 22 is the same as the side length of the cross-section of the first secondary shoulder 21, and the radial length of the cross-section of the second secondary shoulder elastomer 28 is the same as the side length of the cross-section of the second secondary shoulder 29. The materials of the first secondary shoulder elastomer 22 and the second secondary shoulder elastomer 28 are rubber.

[0040] Example 4

[0041] As Figures 1 - 5As shown in the figure, this embodiment proposes an oil and gas pipeline threaded joint, which includes a hollow tubular external threaded joint 1 and an internal threaded joint 2 that are cooperatively arranged. It also includes a first main sealing structure 5, a first auxiliary sealing structure 6, an internal thread 4, an external thread 3, a second auxiliary sealing structure 7, and a second main sealing structure 8 that are arranged in sequence along the axial direction. The interference of the pitch diameters of the external threaded joint 1 and the internal threaded joint 2 is 0.38 mm - 0.51 mm, the taper of the external threaded joint 1 and the internal threaded joint 2 is 1:10, the pitch is 6.35 mm, and the materials of the external threaded joint 1 and the internal threaded joint 2 are fiberglass. The external threaded joint 1 includes a first main shoulder 10, a first sealing groove 14, a second sealing groove 15, an external thread 3, a fourth sealing groove 25, a third sealing groove 24, and a first secondary shoulder 21 that are arranged in sequence along the axial direction; the internal threaded joint 2 includes a second secondary shoulder 29, an internal thread secondary sealing surface 23, an internal thread 4, an internal thread main sealing surface 16, and a second main shoulder 17 that are arranged in sequence along the axial direction.

[0042] The first main sealing structure 5 includes a second main shoulder 17. Along the axial direction of the pipeline, a second main shoulder elastomer 19 is fixedly connected to the second main shoulder 17. The second main shoulder elastomer 19 is in close contact with the first main shoulder elastomer 11. The structures of the second main shoulder elastomer 19 and the first main shoulder elastomer 11 are circular rings with a rhombus cross-section, and the inner angle of the rhombus cross-section is 30°. The first main shoulder elastomer 11 is fixedly connected to the first main shoulder 10 along the axial direction of the pipeline. The radial length of the second main shoulder elastomer 19 is the same as the side length of the cross-section of the second main shoulder 17, and the radial length of the first main shoulder elastomer 11 is the same as the side length of the cross-section of the first main shoulder 10. The materials of the second main shoulder elastomer 19 and the first main shoulder elastomer 11 are rubber. The first auxiliary sealing structure 6 includes a first sealing groove 14 and a second sealing groove 15. The structures of the first sealing groove 14 and the second sealing groove 15 are annular grooves, and they are arranged in parallel on the inner wall of the external threaded joint 1. The first sealing groove 14 is filled with a first non-metallic elastic sealing ring 12, and the second sealing groove 15 is filled with a second non-metallic elastic sealing ring 13. The first non-metallic elastic sealing ring 12 and the second non-metallic elastic sealing ring 13 are in interference contact with the internal thread main sealing surface 16. The materials of the first non-metallic elastic sealing ring 12 and the second non-metallic elastic sealing ring 13 are rubber and Teflon with a compression elastic modulus of 450 GPa.

[0043] The second auxiliary sealing structure 7 includes a third sealing groove 24 and a fourth sealing groove 25. The third sealing groove 24 and the fourth sealing groove 25 are in the shape of annular grooves and are arranged in parallel on the inner wall of the external thread joint 1. The third sealing groove 24 is filled with a third non-metallic elastic sealing ring 26, and the fourth sealing groove 25 is filled with a fourth non-metallic elastic sealing ring 27. The third non-metallic elastic sealing ring 26 and the fourth non-metallic elastic sealing ring 27 are in interference contact with the internal thread pair sealing surface 23. The materials of the third non-metallic elastic sealing ring 26 and the fourth non-metallic elastic sealing ring 27 are rubber and Teflon with a compression elastic modulus of 450 GPa. The second main sealing structure 8 includes a first secondary shoulder 21. The first secondary shoulder 21 is axially fixed with a first secondary shoulder elastic body 22 along the pipeline. The first secondary shoulder elastic body 22 is in close fit with the second secondary shoulder elastic body 28. The structures of the first secondary shoulder elastic body 22 and the second secondary shoulder elastic body 28 are in the shape of an annular ring with a rectangular cross-section. The second secondary shoulder elastic body 28 is axially fixed with a second secondary shoulder 29. The radial length of the cross-section of the first secondary shoulder elastic body 22 is the same as the side length of the cross-section of the first secondary shoulder 21, and the radial length of the cross-section of the second secondary shoulder elastic body 28 is the same as the side length of the cross-section of the second secondary shoulder 29. The materials of the first secondary shoulder elastic body 22 and the second secondary shoulder elastic body 28 are rubber.

[0044] The structure of the external thread 3 is in the form of a number of annular grooves evenly distributed in parallel. The external thread 3 includes an external thread tooth bottom surface 31 provided at the bottom of the groove. The external thread tooth bottom surface 31 is connected to an external thread advancing surface 33 provided on the groove wall through a first transition arc 32. The external thread tooth bottom surface 31 is connected to an external thread loading surface 37 provided on the other groove wall through a fourth transition arc 38. The external thread advancing surface 33 is connected to an external thread tooth top surface 35 through a second transition arc 34. The external thread tooth top surface 35 and the external thread loading surface 37 are connected through a third transition arc 36. The arc radii of both the second transition arc 34 and the third transition arc 36 are 0.40 mm. The arc radii of both the first transition arc 32 and the fourth transition arc 38 are 0.50 mm. The flank angle of the external thread advancing surface 33 is 17°. The flank angle of the external thread loading surface 37 is 22°. The structure of the internal thread 4 is in the form of a number of annular grooves evenly distributed in parallel. The internal thread 4 is arranged in cooperation with the external thread 3. The internal thread 4 includes an internal thread tooth bottom surface 39 provided at the bottom of the groove. The internal thread tooth bottom surface 39 is connected to an internal thread advancing surface 41 provided on the groove wall through a fifth transition arc 40. The internal thread tooth bottom surface 39 is connected to an internal thread loading surface 45 provided on the other groove wall through an eighth transition arc 46. The internal thread loading surface 45 is connected to an internal thread tooth top surface 43 through a seventh transition arc 44. The internal thread tooth top surface 43 and the internal thread advancing surface 41 are connected through a sixth transition arc 42. The arc radii of both the sixth transition arc 42 and the seventh transition arc 44 are 0.40 mm. The arc radii of both the fifth transition arc 40 and the eighth transition arc 46 are 0.50 mm. The flank angle of the internal thread advancing surface 41 is 17°. The flank angle of the internal thread loading surface 45 is 22°.

Claims

1. Oil and gas pipeline threaded joint, Characterized in that: It includes a hollow tubular outer threaded joint (1) and an inner threaded joint (2) that are cooperatively arranged, and also includes a first main sealing structure (5), a first auxiliary sealing structure (6), an internal thread (4), an external thread (3), a second auxiliary sealing structure (7), and a second main sealing structure (8) arranged in sequence along the axial direction.

2. The oil and gas pipeline threaded joint according to claim 1, Characterized in that: The interference of the pitch diameters of the outer threaded joint (1) and the inner threaded joint (2) is 0.38 mm - 0.51 mm, the taper of the outer threaded joint (1) and the inner threaded joint (2) is 1:10, the pitch is 6.34 mm - 6.36 mm, and the materials of the outer threaded joint (1) and the inner threaded joint (2) are fiberglass.

3. The oil and gas pipeline threaded joint according to claim 2, Characterized in that: The outer threaded joint (1) includes a first main shoulder (10), a first sealing groove (14), a second sealing groove (15), an external thread (3), a fourth sealing groove (25), a third sealing groove (24), and a first secondary shoulder (21) arranged in sequence along the axial direction; the inner threaded joint (2) includes a second secondary shoulder (29), an inner thread secondary sealing surface (23), an internal thread (4), an inner thread main sealing surface (16), and a second main shoulder (17) arranged in sequence along the axial direction.

4. The oil and gas pipeline threaded joint according to claim 3, Characterized in that: The first main sealing structure (5) includes a second main shoulder (17), and a second main shoulder elastomer (19) is fixedly connected to the second main shoulder (17) along the axial direction of the pipeline. The second main shoulder elastomer (19) is in close fit with the first main shoulder elastomer (11). The second main shoulder elastomer (19) and the first main shoulder elastomer (11) are in the shape of a circular ring with a rhombus cross-section, and the inner angle of the rhombus cross-section is 29.5° - 30.5°. The first main shoulder elastomer (11) is fixedly connected to the first main shoulder (10) along the axial direction of the pipeline. The radial length of the second main shoulder elastomer (19) is the same as the side length of the cross-section of the second main shoulder (17), and the radial length of the first main shoulder elastomer (11) is the same as the side length of the cross-section of the first main shoulder (10). The materials of the second main shoulder elastomer (19) and the first main shoulder elastomer (11) are rubber.

5. The oil and gas pipeline threaded joint according to claim 4, Characterized in that: The first auxiliary sealing structure (6) includes a first sealing groove (14) and a second sealing groove (15). The first sealing groove (14) and the second sealing groove (15) are in the shape of annular grooves and are arranged in parallel on the inner wall of the external thread joint (1). The first sealing groove (14) is filled with a first non-metallic elastic sealing ring (12), and the second sealing groove (15) is filled with a second non-metallic elastic sealing ring (13). The first non-metallic elastic sealing ring (12) and the second non-metallic elastic sealing ring (13) are in interference contact with the internal thread main sealing surface (16). The materials of the first non-metallic elastic sealing ring (12) and the second non-metallic elastic sealing ring (13) are rubber and Teflon with a compression elastic modulus of 29.5° - 30.5°.

6. The oil and gas pipeline threaded joint according to claim 5, wherein: The second auxiliary sealing structure (7) includes a third sealing groove (24) and a fourth sealing groove (25). The third sealing groove (24) and the fourth sealing groove (25) are in the shape of annular grooves and are arranged in parallel on the inner wall of the external thread joint (1). The third sealing groove (24) is filled with a third non-metallic elastic sealing ring (26), and the fourth sealing groove (25) is filled with a fourth non-metallic elastic sealing ring (27). The third non-metallic elastic sealing ring (26) and the fourth non-metallic elastic sealing ring (27) are in interference contact with the internal thread secondary sealing surface (23). The materials of the third non-metallic elastic sealing ring (26) and the fourth non-metallic elastic sealing ring (27) are rubber and Teflon with a compression elastic modulus of 400 GPa - 500 GPa.

7. The oil and gas pipeline threaded joint according to claim 6, wherein: The second main sealing structure (8) includes a first secondary shoulder (21). The first secondary shoulder (21) is fixedly connected with a first secondary shoulder elastic body (22) along the axial direction of the pipeline. The first secondary shoulder elastic body (22) is in close fit with a second secondary shoulder elastic body (28). The first secondary shoulder elastic body (22) and the second secondary shoulder elastic body (28) are in the shape of an annular ring with a rectangular cross-section. The second secondary shoulder elastic body (28) is fixedly connected with a second secondary shoulder (29) along the axial direction. The radial length of the cross-section of the first secondary shoulder elastic body (22) is the same as the side length of the cross-section of the first secondary shoulder (21). The radial length of the cross-section of the second secondary shoulder elastic body (28) is the same as the side length of the cross-section of the second secondary shoulder (29). The materials of the first secondary shoulder elastic body (22) and the second secondary shoulder elastic body (28) are rubber.

8. The oil and gas pipeline threaded joint according to claim 7, wherein: The external thread (3) is structured as a number of annular grooves evenly distributed in parallel. The external thread (3) includes an external thread tooth bottom surface (31) provided at the groove bottom. The external thread tooth bottom surface (31) is connected to an external thread advancing surface (33) provided on the groove wall through a first transition arc (32). The external thread tooth bottom surface (31) is connected to an external thread loading surface (37) provided on the other groove wall through a fourth transition arc (38). The external thread advancing surface (33) is connected to an external thread tooth top surface (35) through a second transition arc (34). The external thread tooth top surface (35) and the external thread loading surface (37) are connected through a third transition arc (36). The arc radii of the second transition arc (34) and the third transition arc (36) are both 0.35 mm - 0.45 mm. The arc radii of the first transition arc (32) and the fourth transition arc (38) are both 0.45 mm - 0.55 mm. The flank angle of the external thread advancing surface (33) is 16.5° - 17.5°. The flank angle of the external thread loading surface (37) is 21.5° - 22.5°.

9. The oil and gas pipeline threaded joint according to claim 8, characterized in that: The internal thread (4) is structured as a number of annular grooves evenly distributed in parallel. The internal thread (4) is arranged in cooperation with the external thread (3). The internal thread (4) includes an internal thread tooth bottom surface (39) provided at the groove bottom. The internal thread tooth bottom surface (39) is connected to an internal thread advancing surface (41) provided on the groove wall through a fifth transition arc (40). The internal thread tooth bottom surface (39) is connected to an internal thread loading surface (45) provided on the other groove wall through an eighth transition arc (46). The internal thread loading surface (45) is connected to an internal thread tooth top surface (43) through a seventh transition arc (44). The internal thread tooth top surface (43) and the internal thread advancing surface (41) are connected through a sixth transition arc (42). The arc radii of the sixth transition arc (42) and the seventh transition arc (44) are both 0.35 mm - 0.45 mm. The arc radii of the fifth transition arc (40) and the eighth transition arc (46) are both 0.45 mm - 0.55 mm. The flank angle of the internal thread advancing surface (41) is 16.5° - 17.5°. The flank angle of the internal thread loading surface (45) is 21.5° - 22.5°.

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