A bimetallic composite pipe fitting threaded connection structure

Abstract

The application discloses a threaded connection structure of a bimetallic composite pipe fitting, which comprises a bimetallic composite pipe body, a coupling and a saddle-shaped sealing piece. The bimetallic composite pipe body is provided with external threads at the end portion and a plurality of annular grooves on the end face. The coupling is provided with internal threads matched with the external threads of the pipe body at both ends, and is provided with a sealing groove and a supporting beam in the middle portion. The saddle-shaped sealing piece is sleeved in the supporting beam and the sealing groove in the middle portion of the coupling. When the external threads of the pipe body are connected with the threads of the coupling, the end face of the pipe body is in contact with and is extruded by the saddle-shaped rubber sealing piece, thus effectively solving the corrosion problem of the pipe end. Meanwhile, the annular groove structure of the pipe end enables the rubber sealing piece to be elastically deformed and filled into the groove under the extrusion of the end portion of the pipe body, so that the threaded connection has a better sealing function. The threaded connection structure does not need to perform anti-corrosion treatment on the end face of the bimetallic composite pipe and the inner surface of the coupling, thus remarkably reducing the threaded connection cost of the bimetallic pipe, and improving the production efficiency.

Description

Technical Field

[0001] This invention relates to the field of oil casing technology for energy exploration and development such as petroleum, natural gas, and coalbed methane, and particularly to a threaded connection structure for bimetallic composite pipe fittings. Background Technology

[0002] Bimetallic composite pipes, due to their excellent corrosion resistance of the inner layer, are increasingly used in the exploration and development of energy resources such as oil, natural gas, and coalbed methane. For example, they are used to manufacture oil casing to stabilize the wellbore and create oil and gas channels. However, the corrosion resistance between the pipe body and the coupling at the threaded connection of bimetallic pipe fittings is a significant factor limiting their application. This includes potential difference corrosion between the surface substrate and the inner corrosion-resistant alloy layer of the bimetallic pipe, and potential difference corrosion between the pipe body and the coupling material. Currently, the common method for addressing the threaded connection of bimetallic composite pipes is to weld the same corrosion-resistant alloy material onto the pipe end and the coupling surface, ensuring that both the pipe body and the coupling connection use the same corrosion-resistant alloy material. This increases the cost of the threaded connection, adds manufacturing steps, and reduces production efficiency.

[0003] Therefore, it is necessary to study an economical bimetallic composite pipe threaded connection structure to address the shortcomings of existing technologies and to solve or mitigate one or more of the aforementioned problems. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides an economical threaded connection structure for bimetallic composite pipe fittings, which solves the problems of surface potential difference corrosion between the base layer and the corrosion-resistant alloy inner layer of the bimetallic pipe body, as well as the surface potential difference corrosion at the connection between the bimetallic pipe body and the coupling, and the high cost and low production efficiency of welding corrosion-resistant alloy to both the pipe end and the inner surface of the coupling.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a threaded connection structure for bimetallic composite pipe fittings, comprising a bimetallic composite pipe body, a coupling, and a saddle-shaped seal; the pipe end of the bimetallic composite pipe body is machined with a tapered external thread, and the pipe end face of the bimetallic composite pipe body is machined with multiple annular sealing grooves; the two ends of the coupling are respectively machined with internal threads matching the tapered external thread, and the middle of the coupling is machined with a sealing groove and a support beam, the sealing groove being located on both sides of the support beam, the protrusion of the saddle-shaped seal being embedded in the sealing groove, the support beam being embedded in the recess of the saddle-shaped seal, and the saddle-shaped seal being made of an oil-resistant material.

[0006] The outer layer of the bimetallic composite pipe is an outer carbon steel pipe, and the inner layer is an inner corrosion-resistant alloy pipe. The pipe body adopts a metallurgical composite method. The bonding strength between the inner corrosion-resistant alloy pipe and the outer carbon steel pipe is greater than or equal to 300MPa. After the external thread of the pipe body is connected to the internal thread of the coupling, the water sealing pressure of the threaded connection is not less than 35MPa.

[0007] The thickness of the pipe end face is greater than 3.0 mm, and the thickness of the inner corrosion-resistant alloy pipe is greater than 0.8 mm.

[0008] The first annular sealing groove on the end face of the pipe is located inside the inner corrosion-resistant alloy pipe.

[0009] The thickness of the saddle-shaped seal is 2~3mm.

[0010] The annular sealing grooves on the end face of the pipe body are arc-shaped, numbering 2 to 3, and the width of the sealing grooves varies radially from the inside to the outside. The width of the innermost annular sealing groove is 0.4 to 0.6 mm, and the width of the outermost annular sealing groove is 0.5 to 1.0 mm.

[0011] The coupling is an axisymmetric structure, and the coupling is symmetrical about its own axial midplane; the dimensions of the sealing groove and the support beam are respectively matched with the protrusion and recess of the saddle-shaped seal.

[0012] The support beam 22 has a dovetail-shaped structure with an inclination angle of -3° to -5°. The recess of the saddle-shaped seal 3 is also dovetail-shaped, and the inclination angle of the dovetail-shaped recess is the same as that of the dovetail-shaped support beam 22, or the inclination angle is -4° to -6°.

[0013] The end face of the tube is provided with a bevel, and the angle of the bevel is 1° to 3°.

[0014] The thread at the end of the tube is an API thread or a non-API special thread.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: Based on the connection structure described in this invention, the bimetallic tube body does not require welding of a corrosion-resistant alloy layer at the nose end, resulting in lower processing costs. A saddle-shaped seal is provided in the middle of the coupling to prevent corrosion between the coupling materials on the tube end face. The saddle-shaped seal is seated in the middle of the coupling, and through the constraint of the support beam and sealing groove, the saddle-shaped seal is firmly fixed to the inner surface of the coupling. Simultaneously, under pressure, the saddle-shaped seal will also embed into the annular sealing groove, reliably fixing it at the connection point. After the bimetallic tube body and coupling are threaded together, the tube metal... The annular sealing groove on the end face increases the contact area between the saddle-shaped seal and the end face of the pipe body, reducing the risk of corrosion between the outer substrate material and the inner alloy material of the pipe body end face. After the bimetallic pipe body and the coupling are threaded together, the saddle-shaped seal bears the compressive force between the metal end face of the pipe body and the coupling support beam, giving the threaded connection good sealing performance. The sealing pressure under clean water medium is greater than 35MPa. All of the above means that there is no requirement for corrosion resistance of the coupling material, and there is no need to weld corrosion-resistant alloy material onto the inner surface of the coupling. The structure is simple and the processing cost is lower. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of an economical bimetallic composite pipe threaded connection structure provided in one embodiment of the present invention.

[0018] Figure 2 These are schematic diagrams of the pipe end structure, where (a) is a partial cross-sectional structural diagram and (b) is an overall axial schematic diagram of the end face.

[0019] Figure 3 This is a schematic diagram of a partial structure on the middle surface of the coupling.

[0020] Figure 4 This is a schematic diagram of a dovetail-shaped support beam on a coupling.

[0021] Figure 5 This is a schematic diagram of a structure with a step at the end of a tube.

[0022] Figure 6 This is a schematic diagram of a structure with a beveled end face of a tube.

[0023] Wherein: 1-Bimetallic composite pipe body; 2-Coupling; 3-Saddle-shaped seal; 11-Outer carbon steel pipe body; 12-Inner corrosion-resistant alloy pipe; 13-External thread of pipe body; 14-Pipe body end face; 15-Annular sealing groove; 21-Internal thread of coupling; 22-Internal support beam of coupling; 23-Internal sealing groove of coupling. Detailed Implementation

[0024] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0025] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0026] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0027] The present invention provides an economical threaded connection structure for bimetallic composite pipe fittings, comprising a bimetallic composite pipe body 1, a coupling 2, and a saddle-shaped seal 3; the pipe body end is machined with a tapered external thread 13, and the pipe body end face 14 is machined with multiple annular sealing grooves 15; the coupling 2 is machined with internal threads 21 at both ends that match the tapered external thread 13, and a sealing groove 23 and a support beam 22 are machined in the middle of the coupling, the sealing groove 23 is located on both sides of the support beam 22, the protrusion of the saddle-shaped seal 3 is embedded in the sealing groove 23, and the support beam 22 is embedded in the recess of the saddle-shaped seal 3.

[0028] The bimetallic composite pipe body 1 has an outer carbon steel pipe body 11 and an inner corrosion-resistant alloy pipe body 12. The pipe body is constructed using a metallurgical composite method, and the bonding strength between the inner corrosion-resistant alloy pipe body 12 and the outer carbon steel pipe body 11 is greater than or equal to 300 MPa. The thickness of the pipe body end face 14 is greater than 3.0 mm, and the thickness of the inner corrosion-resistant alloy pipe body 12 is greater than 0.8 mm. The annular sealing grooves 15 on the pipe body end face 14 are arc-shaped, numbering 2 to 3, and the width of the sealing grooves varies radially from the inside out, with the innermost annular sealing groove having a width of 0.4 to 0.6 mm and the outermost annular sealing groove having a width of 0.5 to 1.0 mm. The first annular sealing groove 15 on the pipe body end face is located within the corrosion-resistant alloy layer 12. The saddle-shaped seal 3 is made of oil-resistant material with a thickness of 2 to 3 mm, and the support beam 22 has a width of 5 to 10 mm. The coupling 2 has an axisymmetric structure, and the dimensions of the sealing groove 23 and support beam 22 machined in the middle of the coupling match those of the saddle-shaped seal 3. After the external thread 13 of the pipe body is connected to the internal thread 21 of the coupling, the water sealing pressure of the threaded connection is not less than 35 MPa. The external thread 13 at the end of the pipe body is an API thread or a non-API special thread.

[0029] like Figure 1 The present invention discloses an economical bimetallic composite pipe threaded connection structure comprising: a bimetallic composite pipe body 1, a coupling 2, and a saddle-shaped seal 3; the pipe body has a tapered external thread 13 machined at its end, and two annular sealing grooves 15 machined on the pipe body end face 14; the coupling 2 has internal threads 21 at both ends that match the tapered external thread 13, and a sealing groove 23 and a support beam 22 machined in the middle of the coupling; the saddle-shaped rubber seal 3 is made of rubber with a thickness of 2.8 mm.

[0030] like Figure 1 As shown, in one specific embodiment, the outer layer of the bimetallic composite pipe 1 is an outer carbon steel pipe 11, and the inner layer is an inner corrosion-resistant alloy pipe 12. The pipe body adopts a metallurgical composite method, and the bonding strength between the inner corrosion-resistant alloy pipe 12 and the outer carbon steel pipe 11 is 300MPa.

[0031] like Figure 1 As shown, in one specific embodiment, the coupling 2 is an axisymmetric structure, and the coupling 2 is symmetrical about the axial mid-plane.

[0032] like Figure 2 As shown, in one specific embodiment, the thickness of the tube end face 14 is 4.0 mm, and the thickness of the inner corrosion-resistant alloy 12 is 1 mm.

[0033] like Figure 2 As shown, in one specific embodiment, the annular sealing groove 15 on the end face of the pipe body is arc-shaped, and there are two of them. The width of the sealing groove varies from the inside to the outside along the radial direction. The width of the innermost annular sealing groove is 0.4 mm, and the width of the outermost annular sealing groove is 0.6 mm.

[0034] like Figure 2 As shown, in one specific embodiment, the first annular sealing groove 15 on the end face of the pipe body is provided inside the inner corrosion-resistant alloy pipe 12, 0.3 mm away from the inner surface, and the saddle-shaped rubber seal 3 is flush with the inner surface of the pipe body.

[0035] like Figure 3 As shown, in one specific embodiment, the dimensions of the sealing groove 23 and the support beam 22 machined in the middle of the coupling 2 are respectively matched with the protrusion and the recess of the saddle-shaped seal 3. When the saddle-shaped seal 3 is squeezed, it is tightly embedded with the sealing groove 23 and the support beam 22.

[0036] like Figure 3 As shown, in one specific embodiment, after the external thread 13 of the pipe body is connected to the internal thread 21 of the coupling, the water sealing pressure of the threaded connection is 40 MPa.

[0037] like Figure 1 As shown, in one specific embodiment, the external thread 13 at the end of the tube body is an API long round thread.

[0038] refer to Figure 4 The support beam 22 can adopt a dovetail structure with an inclination angle of -3° to -5°. The recess of the saddle-shaped seal 3 is also dovetail-shaped, and the inclination angle of the dovetail shape of the recess is the same as or -4° to -6° as the inclination angle of the dovetail shape of the support beam 22.

[0039] As an optional embodiment, refer to Figure 5 The tube end face 14 can also be provided with a step, and the saddle-shaped seal 3 is provided with lugs on both sides that can be embedded in the step; the lugs are embedded in the step, which can effectively lock the saddle-shaped seal 3 in the sealing position, and the tube end face 14 presses it tightly, which can make it easier to install and improve the reliability of the seal.

[0040] The tube end face 14 described in this application may also be provided with a slope, the slope angle being 1°~3°, see reference. Figure 6 The inclined surface can be set along the entire thickness of the pipe; or it can be set only on the end face, with the part near the inner wall of the pipe being a straight end face. The inclined surface itself forms a space with a tendency to compress, which squeezes the saddle-shaped seal 3 at the connection between the pipe end and the coupling 2.

[0041] The foregoing has provided a detailed description of an economical bimetallic composite pipe threaded connection structure provided in the embodiments of this application. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this application; furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

[0042] Certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The terms "comprising" and "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising / including but not limited to". "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error. The following descriptions in the specification are preferred embodiments for carrying out this application; however, these descriptions are for the purpose of illustrating the general principles of this application and are not intended to limit the scope of this application. The scope of protection of this application shall be determined by the appended claims.

[0043] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes said element.

[0044] The foregoing description illustrates and describes several preferred embodiments of this application. However, as previously stated, it should be understood that this application is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the application concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this application should be within the protection scope of the appended claims.

Claims

1. A threaded connection structure for a bimetallic composite pipe fitting, characterized in that, The system includes a bimetallic composite pipe body (1), a coupling (2), and a saddle-shaped seal (3). The bimetallic composite pipe body (1) has tapered external threads (13) at its end and multiple annular sealing grooves (15) on its end face (14). The first annular sealing groove (15) on the end face is located inside the inner corrosion-resistant alloy pipe (12). The coupling (2) has internal threads (21) that match the tapered external threads (13) at both ends. The coupling has a sealing groove (23) and a support beam (22) in the middle. The sealing groove (23) is located on both sides of the support beam (22). The protrusion of the saddle-shaped seal (3) is embedded in the sealing groove (23), and the support beam (22) is embedded in the recess of the saddle-shaped seal (3). The material is oil-resistant; the support beam (22) is a dovetail structure, and the recess of the saddle-shaped seal (3) is a dovetail; the annular sealing groove (15) of the pipe end face (14) is arc-shaped, with 2 to 3 grooves, and the width of the sealing groove varies from the inside to the outside along the radial direction. The width of the innermost annular sealing groove is 0.4 to 0.6 mm, and the width of the outermost annular sealing groove is 0.5 to 1.0 mm; the support beam (22) and the sealing groove (23) constrain the saddle-shaped seal (3) to be fixed on the inner surface of the coupling. After the threaded connection, the saddle-shaped seal (3) is embedded in the annular sealing groove (15) of the pipe end face, isolating the bimetallic composite pipe end face (14) and the inner surface of the support beam (22) from the corrosive medium. The water sealing pressure of the threaded connection is not less than 35 MPa.

2. The threaded connection structure of the bimetallic composite pipe fitting according to claim 1, characterized in that, The outer layer of the bimetallic composite pipe body (1) is an outer carbon steel pipe body (11), and the inner layer is an inner corrosion-resistant alloy pipe (12). The pipe body adopts a metallurgical composite method, and the bonding strength between the inner corrosion-resistant alloy pipe (12) and the outer carbon steel pipe body (11) is greater than or equal to 300MPa.

3. The threaded connection structure of the bimetallic composite pipe fitting according to claim 1, characterized in that, The thickness of the end face (14) of the tube body is greater than 3.0 mm, and the thickness of the inner corrosion-resistant alloy tube (12) is greater than 0.8 mm.

4. The threaded connection structure of the bimetallic composite pipe fitting according to claim 1, characterized in that, The thickness of the saddle-shaped seal is 2~3mm.

5. The threaded connection structure of the bimetallic composite pipe fitting according to claim 1, characterized in that, The coupling (2) is an axisymmetric structure, and the coupling (2) is symmetrical about its own axial mid-plane; the dimensions of the sealing groove (23) and the support beam (22) are matched with the protrusion and recess of the saddle-shaped seal (3) respectively.

6. The threaded connection structure of the bimetallic composite pipe fitting according to claim 1, characterized in that, The inclination angle of the dovetail shape of the support beam (22) is -3° to -5°, and the inclination angle of the dovetail shape of the recess is the same as or -4° to -6° as the inclination angle of the dovetail shape of the support beam (22).

7. The threaded connection structure of the bimetallic composite pipe fitting according to claim 1, characterized in that, The end face (14) of the tube body is provided with a bevel, and the angle of the bevel is 1°~3°.

8. The threaded connection structure of the bimetallic composite pipe fitting according to claim 1, characterized in that, The thread at the end of the tube is an API thread.

Images