Non-metallic pipe expansion joint, pipe and method of installing the joint

Abstract

The application provides a non-metal oil pipe expansion joint, an oil pipe and a method for installing the joint. The non-metal pipe body of the oil pipe comprises a tubular reinforcing layer and a tubular inner lining layer located in the reinforcing layer, and the inner lining layer is tightly combined with the reinforcing layer. The joint comprises a joint body which is tubular and has a connecting thread at one end; and an expansion sleeve which is tubular, coaxial with the joint body and located in the joint body. In the installed state of the joint body and the expansion sleeve, a part of the outer wall of the expansion sleeve can be pressed against the inner wall of the joint body, and another part of the outer wall of the expansion sleeve can directly press the part of the reinforcing layer between the outer wall of the expansion sleeve and the inner wall of the joint body against the inner wall of the joint body, so that the outer wall of the reinforcing layer is tightly fitted and fixed with the inner wall of the joint body. The non-metal oil pipe expansion joint, the oil pipe and the method for installing the joint provided by the application can overcome the shortcomings of low connection bearing capacity and poor temperature resistance between the joint and the pipe body of the existing non-metal oil pipe.

Description

Technical Field

[0001] This invention relates to the field of oil and gas transportation, and in particular to a non-metallic oil pipe expansion joint, an oil pipe and a joint installation method. Background Technology

[0002] In existing technologies, seamless steel pipes are widely used in oil and gas extraction. Commonly used tubing consists of a pipe body and fittings, with the pipe bodies connected and sealed by tapered threads at both ends of the fittings. Multiple sections of tubing are connected together and extended downhole. The complex downhole conditions and the reciprocating motion of the sucker rod easily cause tubing wear, corrosion, scaling on the pipe walls, and damage to the tapered threads. Damage to metal tubing inevitably leads to frequent well workovers, reducing oil and gas production efficiency and increasing extraction costs.

[0003] Oil pipes are prone to wear, corrosion, and scaling. Currently, the most common approach is to apply a coating to the inner wall of the pipe. However, it is difficult to remove rust completely from the inner wall of the pipe, resulting in low adhesion of the inner wall coating. In particular, during use, the coating with low adhesion will gradually peel off and detach. The detached paint impurities may even cause pump jamming accidents. Therefore, the application of oil pipe inner coating technology is limited.

[0004] Currently, the most advanced technology for solving various problems with oil pipelines is to install a polyethylene liner on the inner wall of the pipeline, which can solve problems such as wear, corrosion, and scaling of the pipeline body to a certain extent. However, due to the liner material and installation process, the liner does not adhere well to the pipeline body, causing problems such as liner peeling, loosening, and unstable service life. On the other hand, installing a liner requires a high level of cleanliness and precision on the inner surface of the pipeline. The installation process involves cumbersome steps such as diameter reduction, pipe threading, heating, and flanging, resulting in high manufacturing costs and hindering its widespread application.

[0005] Patent CN107351344A discloses a method for manufacturing non-metallic oil pipes used in oil and gas fields, including a pipe body and couplings. Both the pipe body and couplings comprise a heat-resistant layer, an intermediate reinforcing layer, and an anti-corrosion layer. The heat-resistant layer is a heat-resistant polymer formed by polymerizing polyethylene or butadiene with a molecular weight of 1.5 million to 3.2 million under a rigid catalyst. The intermediate reinforcing layer is composed of high-pressure resistant glass fiber, reinforced polyester fiber, aramid fiber, polyethylene fiber, and a mesh of high-strength steel wire. The anti-corrosion layer is made of polyethylene with a molecular weight of 2.5 million to 4.2 million. This method uses a method of directly fabricating tapered threads between the inner and outer layers of the composite pipe for connection: "Each inner conical boss has a through-hole internal tapered pipe thread formed by threaded molding. The nominal inner diameter of the inner tapered pipe thread is equal to the nominal outer diameter of the outer tapered pipe thread. The through-hole internal tapered pipe thread of the coupling connects the outer tapered pipe threads of two adjacent pipe bodies, and so on."

[0006] Further research revealed that directly using threaded molding to manufacture tubing joints results in very limited connection strength. This is primarily because the reinforcing layer in the core of the composite pipe cannot continuously transmit axial force, and the axial force at the joint is borne by the polymer of the inner lining or outer protective layer. Especially in the high-temperature environment downhole, the polymer material softens to some extent, further reducing its mechanical properties.

[0007] Patent CN001128485 discloses a connection method for metal-reinforced plastic composite pipes. The technical solution involves fabricating a plastic flange that meets the working pressure requirements for connection. This method uses a plastic flange to connect the composite pipes, employing adhesives or fusion welding; however, the connection strength is limited, making it unsuitable for high-pressure applications and significantly restricting its use. Furthermore, this method connects the inner and outer layers of the composite pipe, meaning the reinforcing layer of the main pipe body cannot continuously transmit axial force, making it difficult to apply to downhole pipe string connections.

[0008] Patent CN201720358773.6 discloses a hydraulic hose connector. Existing hydraulic hose end metal connectors typically use a crimping method for installation. With an inner metal support, an outer sleeve is fitted over the pipe and the connection is achieved through compression. While this method is simple to operate, the multiple layers of the pipe are crimped in a single operation, and the outer layer material is relatively soft, resulting in poor pull-out resistance of the connector. Therefore, this technical solution is difficult to apply to downhole tubing.

[0009] Based on the above technical background, inventing safer and more reliable non-metallic oil pipe joints has practical significance and application prospects, and the innovation and research and development of related technologies have great application value. Summary of the Invention

[0010] This invention provides a non-metallic oil pipe expansion joint that can overcome the shortcomings of existing non-metallic oil pipe joints and pipe bodies, such as low load-bearing capacity and poor temperature resistance.

[0011] The present invention provides a non-metallic oil pipe expansion joint, wherein the non-metallic body of the oil pipe includes a tubular reinforcing layer and a tubular inner liner layer located within the reinforcing layer, the inner liner layer being tightly bonded to the reinforcing layer, characterized in that the joint comprises:

[0012] The connector body is tubular, and one end of the connector body is provided with a connecting thread;

[0013] An expansion sleeve, which is tubular, is located within the connector body and coaxial with it. When the connector body and the expansion sleeve are installed, a portion of the outer wall of the expansion sleeve can be pressed against the inner wall of the connector body, while another portion can directly press the portion of the reinforcing layer located between the outer wall of the expansion sleeve and the inner wall of the connector body against the inner wall of the connector body, so that the outer wall of the reinforcing layer and the inner wall of the connector body form a tight fit and fixation.

[0014] Preferably, the end of the inner liner is provided with an annular embedding groove, the annular opening is located on the end wall of the inner liner and the depth is parallel to the axis of the inner liner, and the end of the expansion sleeve away from the connecting thread of the connector body is embedded in the annular embedding groove.

[0015] Preferably, the inner wall of the connector body has annular first, second, and third steps arranged sequentially from one end to the other, with the diameters of the first, second, and third steps increasing sequentially. The connecting thread is located at the end of the connector body with the first step. When the connector body and the expansion sleeve are installed, a portion of the inner wall of the expansion sleeve can press against the outer wall of the second step of the connector body, and another portion can directly press the portion of the reinforcing layer located between the outer wall of the expansion sleeve and the inner wall of the third step against the outer wall of the third step, so that the outer wall of the reinforcing layer and the inner wall of the third step form a tight fit and fixation. The inner wall of the third step has multiple annular first protrusions. The inner wall of the second step has a first annular groove circumferentially surrounding the second step.

[0016] Preferably, the outer wall of the connector body is provided with knurling or a second annular groove circumferentially surrounding the connector body. The outer wall of the connector body also provides a third annular groove, the depth of which is greater than the depth of the knurling or second annular groove. The connector further includes a cylindrical connector protective layer covering the outside of the connector body. One end of the connector protective layer at least covers the third annular groove, and the other end at least covers the junction between the end of the connector body away from the connecting thread and the reinforcing layer. The outer wall of the connector body decreases in outer diameter at a position opposite to the second and third steps to form a fourth step. The third annular groove and the knurling or second annular groove are provided on the outer wall of the fourth step.

[0017] Preferably, the thickness of the reinforcing layer located between the outer wall of the expansion sleeve and the inner wall of the connector body is greater than the thickness of other portions; and / or the reinforcing layer is formed by interlacing fibers or fiber tapes.

[0018] Preferably, when the connecting thread is formed on the outer wall of the first step, the connector constitutes a male connector, and when the connecting thread is formed on the inner wall of the first step, the connector constitutes a female connector.

[0019] The present invention also provides an oil pipe, comprising a non-metallic pipe body, wherein at least one end of the pipe body is connected to a connector as described above.

[0020] The present invention also provides another type of oil pipe, comprising a non-metallic pipe body, one end of which is connected to a male connector as described above, and the other end of which is connected to a female connector as described above.

[0021] The present invention also provides a method for installing a connector, for connecting the connector to a non-metallic pipe body of an oil pipe, the non-metallic pipe body comprising a tubular reinforcing layer and a tubular inner liner layer located within the reinforcing layer, the inner liner layer being tightly bonded to the reinforcing layer, comprising the following steps:

[0022] (1) Place the expansion sleeve inside the connector body;

[0023] (2) Ring-strip the inner lining at the end of the pipe body and extend the end of the reinforcing layer between the joint body and the expansion sleeve;

[0024] (3) Insert the expansion device into the expansion sleeve and apply a radially outward force to the expansion sleeve to expand and deform the expansion sleeve and press the reinforcing layer tightly against the inner wall of the joint body, and then remove the expansion device from the expansion sleeve.

[0025] Preferably, step (2) further includes the following operation: an annular embedding groove is opened at the end of the inner liner, the opening of the annular embedding groove is located on the end wall of the end of the inner liner, and the depth is parallel to the axis of the inner liner, and the end of the expansion sleeve away from the connecting thread of the connector body is embedded in the annular embedding groove.

[0026] Preferably, the inner wall of the connector body has annular first, second, and third steps arranged sequentially from one end to the other, with the diameters of the first, second, and third steps increasing sequentially. The connecting thread is located at the end of the connector body where the first step is located. In step (1), the length of the inner liner removed is the same as the length of the third step of the connector. In step (3), the expansion sleeve expands and deforms, with one part pressing the reinforcing layer against the inner wall of the third step of the connector body to fix the expansion sleeve, reinforcing layer, and third step together. The other part presses against the inner wall of the second step of the connector body and is fixed together with the second step. The inner wall of the third step has multiple annular first protrusions. The inner wall of the second step has a first annular groove circumferentially surrounding the second step.

[0027] Preferably, the outer wall of the connector body is provided with knurling or a second annular groove that surrounds the connector body circumferentially, and the outer wall of the connector body is also provided with a third annular groove. The depth of the third annular groove is greater than the depth of the knurling or the second annular groove. The installation method further includes step (4), covering the outside of the connector body with a cylindrical connector protective layer. One end of the connector protective layer can at least cover the third annular groove, and the other end of the connector protective layer can at least cover the junction between the end of the connector body away from the connecting thread and the outer wall of the reinforcing layer.

[0028] Preferably, the outer diameter of the connector body is reduced at a position opposite to the second and third steps to form a fourth step, and the third annular groove and knurling or the second annular groove are provided on the outer wall of the fourth step.

[0029] Preferably, in step (4), the joint protective layer is formed by injection molding the outer wall of the joint body and the outer wall of the part of the reinforcing layer near the joint. During injection molding, the injection material enters the third annular groove and the second annular groove or knurling.

[0030] Preferably, the thickness of the portion of the reinforcing layer extending between the joint body and the expansion sleeve is greater than the thickness of the other portions; and / or the reinforcing layer is formed by interlacing fibers or fiber tapes.

[0031] The non-metallic oil pipe expansion joint, oil pipe, and installation method of the present invention have the following advantages compared with the prior art:

[0032] 1. The expansion sleeve of the joint can press the reinforcing layer of the pipe body tightly against the inner wall of the joint body. The axial force between the joint and the pipe body is borne by the reinforcing layer, which has a greater strength than the inner lining layer and can withstand a greater axial force. Therefore, a more stable connection can be obtained than that of traditional joints. Through testing and analysis, the joint and the pipe body can withstand an internal pressure of up to 45 MPa, meeting the needs of conventional downhole oil production.

[0033] 2. The inner lining of the pipe body has an annular groove with an opening on its end wall. The depth of the annular groove is parallel to the axial direction of the inner lining. The end of the expansion sleeve away from the connecting thread of the connector body is embedded in the annular groove. This design creates a more stable and reliable connection between the end of the inner lining and the expansion sleeve. Under the radial outward pressure generated by the medium in the pipe body, the inner lining undergoes radial deformation, and its annular groove can more tightly wrap the end of the expansion sleeve, forming a self-sealing between the inner lining and the expansion sleeve. The higher the pressure of the medium, the more reliable the seal. At the same time, the stronger the connection between the inner lining and the expansion sleeve, the stronger the connection between the connector body and the pipe body is. Attached Figure Description

[0034] Figure 1This is a schematic diagram of the structure of a non-metallic oil pipe expansion joint and the oil pipe body in an embodiment of the present invention, when they are assembled but not yet expanded.

[0035] Figure 2 This is a schematic diagram of the structure of a non-metallic oil pipe expansion joint and the oil pipe body during expansion connection according to another embodiment of the present invention.

[0036] Figure 3 for Figure 2 A partially enlarged schematic diagram of the expansion joint of a non-metallic oil pipe and the expansion joint of the oil pipe body.

[0037] Figure Labels

[0038] 1. Connector body; 11. First step; 12. Connecting thread; 13. Second step; 14. First protrusion; 15. Third step; 16. Fourth step; 17. First annular groove; 18. Second annular groove; 19. Third annular groove.

[0039] 2. Expansion sleeve;

[0040] 3. Connector protective layer;

[0041] 4. Pipe body, 41. Reinforcing layer, 42. Inner lining layer, 43. Pipe body protective layer, 44. Annular embedded groove.

[0042] 5. Expansion joint device. Detailed Implementation

[0043] This invention provides a non-metallic oil pipe expansion joint for connecting to the non-metallic pipe body 4 of an oil pipe, such as... Figure 1-3 As shown, the non-metallic pipe body 4 of the oil pipe includes a tubular reinforcing layer 41 and a tubular inner liner 42 located within the reinforcing layer 41, and a pipe body protective layer 43 outside the reinforcing layer. The reinforcing layer 41, the inner liner 42, and the pipe body protective layer 43 are all made of non-metallic materials. The inner liner 42 is tightly bonded to the reinforcing layer 41. The connector includes a connector body 1 and an expansion sleeve 2. The connector body 1 is tubular, and one end of the connector body 1 is provided with a connecting thread 12. The expansion sleeve 2 is tubular, located inside the connector body 1, and coaxial with the connector body 1. After being subjected to radial outward compression deformation, that is, in the state where the connector body and the expansion sleeve are installed, a part of its inner wall can be pressed against the inner wall of the connector body 1, and another part can directly press the portion of the reinforcing layer 41 located between the outer wall of the expansion sleeve 2 and the inner wall of the connector body 1 against the inner wall of the connector body 1, so that the outer wall of the reinforcing layer and the inner wall of the connector body form a tight fit and fixation.

[0044] The non-metallic tubing expansion joint of this invention allows the expansion sleeve 2 to press the reinforcing layer 41 of the tubing 4 against the inner wall of the joint body 1. The axial force between the joint and the tubing 4 is borne by the reinforcing layer 41, which has a greater strength than the inner lining layer 42 and can withstand a greater axial force. Therefore, a more stable connection than traditional joints can be achieved. Through testing and analysis, the joint and tubing 4 can withstand an internal pressure of up to 45 MPa, meeting the requirements of conventional downhole oil production.

[0045] As a preferred solution, such as Figure 1 As shown, the inner liner has an annular groove with an opening on its end wall at its end, and the depth direction of the annular groove is parallel to the axial direction of the inner liner. The end of the expansion sleeve away from the connecting thread of the connector body is embedded in the annular groove. This design makes the connection between the end of the inner liner and the expansion sleeve more stable and reliable. Under the radial outward pressure generated by the medium in the pipe, the inner liner undergoes radial deformation, and its annular groove can more tightly wrap the end of the expansion sleeve, forming a self-sealing between the inner liner and the expansion sleeve. The greater the pressure of the medium, the more reliable the seal. At the same time, the stronger the connection between the inner liner and the expansion sleeve, the stronger the connection between the connector body and the pipe body is also further improved.

[0046] like Figure 1 As shown, the inner wall of the connector body 1 has annular first step 11, second step 13 and third step 15 arranged sequentially from one end to the other. The diameters of the first step 11, second step 13 and third step 15 increase sequentially. The connecting thread 12 is located at the end of the connector body 1 where the first step 11 is provided. After the expansion sleeve 2 is subjected to radial outward compression deformation, that is, in the state where the connector body and the expansion sleeve are installed, a part of its inner wall can be pressed against the outer wall of the second step 13 of the connector body 1, and another part can directly press the part of the reinforcing layer 41 located between the outer wall of the expansion sleeve 2 and the inner wall of the third step 15 against the outer wall of the third step 15 so that the outer wall of the reinforcing layer 41 and the inner wall of the third step form a tight fit and fixation.

[0047] like Figure 3 As shown, the inner wall of the third step 15 is provided with multiple annular first protrusions 14. The inner wall of the second step 13 is provided with a first annular groove 17 circumferentially surrounding the second step 13. When the expansion sleeve 2 is subjected to radial outward compression and expands outward, the portion of the expansion sleeve 2 opposite to the first annular groove 17 of the second step 13 deforms and enters into the first annular groove 17, cooperating with the side wall of the first annular groove 17, thereby increasing the axial load-bearing capacity. At the same time, the portion of the reinforcing layer 41 opposite to the third step 15 deforms under the action of the first protrusions 14, conforming to the shape of the first protrusions 14, also increasing the axial load-bearing capacity.

[0048] The outer wall of the connector body 1 is provided with knurling or a second annular groove 18 circumferentially surrounding the connector body 1. In this embodiment, the outer wall of the connector body 1 is provided with a second annular groove 18. The outer wall of the connector body 1 is also provided with a third annular groove 19, the depth of which is greater than the depth of the knurling or the second annular groove 18. The connector also includes a cylindrical connector protective layer 3 covering the outside of the connector body 1. One end of the connector protective layer 3 can at least cover the third annular groove 19, and the other end can at least cover the junction of the connector body 1 away from the connecting thread and the outer wall of the reinforcing layer 41. At the same time, the connector protective layer 3 is connected to the tube body protective layer 43 of the tube body. The connector protective layer 3 can protect the connector body 1 and can seal the junction of the connector body 1 away from the connecting thread 12 and the reinforcing layer 41, preventing external impurities from entering between the reinforcing layer 41 and the connector body 1.

[0049] In this embodiment, the outer diameter of the outer wall of the connector body 1 decreases at a position opposite to the second step 13 and the third step 15 to form a fourth step 16. The third annular groove 19 and the knurled or second annular groove 18 are provided on the outer wall of the fourth step 16. The connector protective layer 3 is formed by injection molding or winding, and the diameter of the outer wall of the connector protective layer 3 is the same as the diameter of other parts of the outer wall of the connector body 1. During injection molding, the injection material enters the knurled or second annular groove 18 on the outer wall of the fourth step 16 and can enter the third annular groove 19. The connector protective layer 3 formed by the injection material cooperates with the inner wall of the knurled or second annular groove 18 and the third annular groove 19, increasing the bonding force between the injection material and the connector body 1, thus making it less likely to detach from the connector body 1.

[0050] In this embodiment, the thickness of the reinforcing layer 41 located between the outer wall of the expansion sleeve 2 and the inner wall of the connector body 1 is greater than the thickness of other parts, and it is formed by interlacing fibers or fiber tapes, which can further improve the force that the connector can bear after being connected to the pipe body 4.

[0051] When the connecting thread 12 is formed on the outer wall of the first step 11, the connector constitutes a male connector. In this embodiment, as shown... Figure 1 and Figure 2 As shown, the connector body 1 on the right is a male connector. The outer wall of one end of the connector body 1 with a first step 11 gradually increases in the axial direction starting from the end of the connector body 1, and the outer wall of this end is provided with external threads. When the connecting thread 12 is formed on the inner wall of the first step 11, the connector constitutes a female connector. In this embodiment, as... Figure 1 and Figure 2As shown, the connector body 1 on the left is a male connector. The inner wall of the end of the connector body 1 with the first step 11 gradually narrows in the axial direction starting from the end of the connector body 1, and the inner wall of this end is provided with internal threads.

[0052] The present invention also provides an oil pipe, comprising a non-metallic pipe body 4, one end of which is connected to a connector as described above, which can be a female connector or a male connector. The other end of the pipe body 4 can be connected to other equipment or connectors.

[0053] The present invention also provides another type of oil pipe, comprising a non-metallic pipe body 4, one end of which is connected to a male connector as described above, and the other end of which is connected to a female connector as described above. When it is necessary to connect two sections of pipe body 4 together, the male connector of one pipe body 4 can be connected to the female connector of the other pipe body 4 by means of threads.

[0054] The present invention also provides a method for installing a connector for connecting the connector to a non-metallic pipe body 4 of an oil pipe. The non-metallic pipe body 4 includes a tubular reinforcing layer 41 and a tubular inner liner 42 located within the reinforcing layer 41, and also includes a pipe body protective layer 43 outside the reinforcing layer 41. The inner liner 42 is tightly bonded to the reinforcing layer 41. The method includes the following steps:

[0055] (1) Place the expansion sleeve 2 inside the connector body 1;

[0056] (2) Remove the inner lining layer 42 at the end of the pipe body 4 and extend the end of the reinforcing layer 41 between the joint body 1 and the expansion sleeve 2.

[0057] (3) Insert the expansion device 5 into the expansion sleeve 2 and apply a radially outward force to the expansion sleeve 2 to expand and deform the expansion sleeve 2, pressing the reinforcing layer 41 against the inner wall of the joint body 1, and then remove the expansion device from the expansion sleeve. The expansion device 5 can be an existing conventional expansion device.

[0058] Using the joint installation method of the present invention, the expansion sleeve 2 can press the reinforcing layer 41 of the pipe body 4 tightly against the inner wall of the joint body 1. The axial force between the joint and the pipe body 4 is borne by the reinforcing layer 41, and the strength of the reinforcing layer 41 is greater than that of the inner lining layer 42. Its axial force capacity is also greater than that of the inner lining layer 42, thus achieving a more stable connection than traditional joints. Through testing and analysis, the joint and pipe body 4 can withstand an internal pressure of up to 45 MPa, meeting the requirements of conventional downhole oil production.

[0059] As a preferred embodiment, step (2) further includes the following operation: an annular embedding groove is opened at the end of the inner liner, the opening of the annular embedding groove is located on the end wall of the end of the inner liner, and the depth is parallel to the axis of the inner liner, and the end of the expansion sleeve away from the connecting thread of the connector body is embedded in the annular embedding groove, the depth of the annular embedding groove is parallel to the axis of the inner liner.

[0060] In this embodiment, the thickness of the reinforcing layer 41 located between the outer wall of the expansion sleeve 2 and the inner wall of the connector body 1 is greater than the thickness of other parts, and it is formed by interlacing fibers or fiber tapes, which can further improve the force that the connector can bear after being connected to the pipe body 4.

[0061] The inner wall of the connector body 1 has annular first step 11, second step 13 and third step 15 arranged sequentially from one end to the other. The diameters of the first step 11, second step 13 and third step 15 increase sequentially. The connecting thread 12 is located at the end of the connector body 1 where the first step 11 is provided. In step (1), the length of the inner lining layer 42 that is peeled off is the same as the length of the third step 15 of the connector. In step (3), the expansion sleeve 2 expands and deforms a part of its portion to press the reinforcing layer 41 against the inner wall of the third step 15 of the connector body 1, so that the expansion sleeve 2, the reinforcing layer 41 and the third step 15 are fixed together. The other part is pressed against the inner wall of the second step 13 of the connector body 1 and fixed together with the second step 13.

[0062] The inner wall of the third step 15 is provided with multiple annular first protrusions 14. The inner wall of the second step 13 is provided with a first annular groove 17 that circumferentially surrounds the second step 13. When the expansion sleeve 2 expands outward under radial outward force, the portion of the expansion sleeve 2 opposite to the first annular groove 17 of the second step 13 deforms and enters into the first annular groove 17, cooperating with the side wall of the first annular groove 17, thereby increasing the axial load-bearing capacity. At the same time, the portion of the reinforcing layer 41 opposite to the third step 15 deforms under the action of the first protrusions 14, conforming to the shape of the first protrusions 14, which also increases the axial load-bearing capacity.

[0063] The outer wall of the connector body 1 is provided with knurling or a second annular groove 18 circumferentially surrounding the connector body 1. In this embodiment, the outer wall of the connector body 1 is provided with a second annular groove 18. The outer wall of the connector body 1 is also provided with a third annular groove 19, the depth of which is greater than the depth of the knurling or the second annular groove 18. The connector also includes a cylindrical connector protective layer 3 covering the outside of the connector body 1. The installation method of the connector of the present invention further includes step (4), covering the outside of the connector body 1 with a cylindrical connector protective layer 3. One end of the connector protective layer 3 can at least cover the third annular groove 19, and the other end of the connector protective layer 3 can at least cover the end of the connector body 1 away from the connecting thread 12 where it connects with the reinforcing layer 41. The connector protective layer 3 is connected to the pipe body protective layer 43. The connector protective layer 3 can protect the connector body 1 and can seal the connection between the outer wall of the connector body 1 away from the end provided with the connecting thread 12 and the outer wall of the reinforcing layer 41, preventing external impurities from entering between the reinforcing layer 41 and the connector body 1.

[0064] In step (4), the joint protective layer 3 is formed by injection molding the outer wall of the joint body 1 and the outer wall of the reinforcing layer 41 near the joint. During injection molding, the injection material enters the third annular groove 19 and the second annular groove 18 or knurling, so that the joint protective layer 3 formed by the injection molding material can generate a greater bonding force with the joint body 1, thus making it less likely to detach from the joint body. In this embodiment, the outer diameter of the outer wall of the joint body 1 decreases at the position opposite to the second step 13 and the third step 15 to form a fourth step 16. The third annular groove 19 and the knurling or second annular groove 18 are provided on the outer wall of the fourth step 16. The diameter of the outer wall of the injection-molded joint protective layer 3 is the same as the diameter of other parts of the outer wall of the joint body 1.

[0065] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. The scope of protection of the present invention is defined by the claims. Various modifications or equivalent substitutions made by those skilled in the art to the present invention within its spirit and scope of protection also fall within the scope of protection of the present invention.

Claims

1. A non-metallic tubing expansion joint, the non-metallic tubing body of the tubing comprising a tubular reinforcing layer and a tubular inner liner layer located within the reinforcing layer, the inner liner layer being intimately bonded together with the reinforcing layer, characterised in that, The joint comprises: The joint body is tubular, one end of the joint body is provided with a connecting thread, the inner wall of the joint body is provided with annular first, second and third steps arranged in sequence from one end to the other end, the diameters of the first, second and third steps increase in sequence, the connecting thread is located at the end of the joint body provided with the first step, the outer wall of the joint body is provided with knurling or a second annular groove circumferentially surrounding the joint body, the outer wall of the joint body is further provided with a third annular groove, the depth of the third annular groove is greater than the depth of the knurling or the second annular groove, the joint further comprises a tubular joint protective layer covering the outside of the joint body, one end of the joint protective layer can cover at least the third annular groove, the other end can cover at least the joint between the end of the joint body away from the connecting thread and the reinforcing layer; The expansion sleeve is tubular, the expansion sleeve is located inside the joint body and coaxial with the joint body, in the state that the joint body and the expansion sleeve are installed, a part of the outer wall of the expansion sleeve can be pressed against the second step of the joint body, another part can directly press the part of the reinforcing layer between the outer wall of the expansion sleeve and the inner wall of the third step to the third step, so that the outer wall of the reinforcing layer and the inner wall of the third step form a tight fit and fixation; The inner lining layer end is provided with an annular embedding groove, the opening of the annular embedding groove is located on the end wall of the inner lining layer and the depth is parallel to the axis of the inner lining layer, the end of the expansion sleeve away from the connecting thread of the joint body is embedded into the annular embedding groove.

2. The non-metallic oil pipe expansion joint of claim 1, wherein, The inner wall of the third step is provided with a plurality of annular first protrusions.

3. The non-metallic oil pipe expansion joint of claim 1, wherein, The inner wall of the second step is provided with a first annular groove circumferentially surrounding the second step.

4. The non-metallic oil pipe expansion joint of claim 1, wherein, The outer wall of the joint body is reduced in diameter at a position opposite to the second step and the third step to form a fourth step, the third annular groove and the knurling or the second annular groove are arranged on the outer wall of the fourth step.

5. The non-metallic oil pipe expansion joint of claim 1, wherein, The thickness of the part of the reinforcing layer between the outer wall of the expansion sleeve and the inner wall of the joint body is greater than the thickness of other parts; and / or the reinforcing layer is formed by interlaced winding of fibers or fiber belts.

6. The non-metallic oil pipe expansion joint of claim 1, wherein, When the connecting thread is formed on the outer wall of the first step, the joint constitutes a male joint, when the connecting thread is formed on the inner wall of the first step, the joint constitutes a female joint.

7. A tubing comprising a non-metallic tubing body, characterized in that At least one end of the pipe body is connected with the joint as claimed in any one of claims 1-5.

8. A tubing comprising a non-metallic tubing body, characterized in that, One end of the pipe body is connected with the male joint as claimed in claim 6, and the other end of the pipe body is connected with the female joint as claimed in claim 6.

9. A method of installing a joint, characterised in that, For connecting the joint as claimed in any one of claims 1-6 with a non-metallic pipe body of the oil pipe, the non-metallic pipe body comprises a tubular reinforcing layer and a tubular inner lining layer located inside the reinforcing layer, the inner lining layer is tightly combined with the reinforcing layer, comprising the following steps: (1) placing the expansion sleeve inside the joint body; (2) ring stripping the inner lining layer at the end of the pipe body, and extending the end of the reinforcing layer between the joint body and the expansion sleeve; (3) the expanding device is extended into the expanding sleeve to apply a radially outward force to the expanding sleeve to expand the expanding sleeve and compress the reinforcing layer against the inner wall of the joint body, and then the expanding device is withdrawn from the expanding sleeve.

10. The mounting method according to claim 9, wherein The step (2) further comprises the following operation: an annular embedding groove is formed at the end of the inner liner, the opening of the annular embedding groove is located at the end wall of the end of the inner liner, and the depth is parallel to the axis of the inner liner, and the end of the expanding sleeve away from the connecting thread of the joint body is embedded into the annular embedding groove.

11. The method of installing of claim 10, wherein, The inner wall of the joint body has an annular first step, a second step and a third step arranged in sequence from one end to the other end, the diameters of the first step, the second step and the third step increase in sequence, the connecting thread is located at the end of the joint body provided with the first step, the length of the inner liner stripped in step (1) is the same as the length of the third step of the joint, and in step (3), a part of the expanding sleeve expands and deforms to compress the reinforcing layer against the inner wall of the third step of the joint body to fix the expanding sleeve, the reinforcing layer and the third step together, and the other part is compressed against the inner wall of the second step of the joint body to fix the second step together.

12. The method of installing of claim 11, wherein, The inner wall of the third step is provided with a plurality of annular first protrusions.

13. The method of installing of claim 11, wherein, The inner wall of the second step is provided with a first annular groove circumferentially surrounding the second step.

14. The method of installing of claim 11, wherein, The outer wall of the joint body is provided with a knurl or a second annular groove circumferentially surrounding the joint body, and the outer wall of the joint body is further provided with a third annular groove, the depth of the third annular groove is greater than the depth of the knurl or the second annular groove, and the installation method further comprises step (4): a tubular joint protective layer is wrapped outside the joint body, one end of the joint protective layer can cover at least the third annular groove, and the other end of the joint protective layer can cover at least the joint between the end of the joint body away from the connecting thread and the outer wall of the reinforcing layer.

15. The method of mounting of claim 14, wherein, The outer diameter of the joint body is reduced at a position opposite to the second step and the third step to form a fourth step, and the third annular groove and the knurl or the second annular groove are arranged on the outer wall of the fourth step.

16. The method of installing a joint of claim 14, wherein, In step (4), the joint protective layer is formed by injection molding on the outer wall of the joint body and the outer wall of the part of the reinforcing layer close to the joint, and during injection molding, the injection molding material enters the third annular groove and the second annular groove or the knurl.

17. The method of installing of claim 9, wherein, The thickness of the part of the reinforcing layer extending between the joint body and the expanding sleeve is greater than the thickness of other parts; and / or the reinforcing layer is formed by interlaced winding of fibers or fiber belts. The thickness of the part of the reinforcing layer extending between the joint body and the expanding sleeve is greater than the thickness of other parts; and / or the reinforcing layer is formed by interlaced winding of fibers or fiber belts.

Images