A method for reinforcing the socket of large-diameter flexible joint steel pipe

Abstract

This invention discloses a method for reinforcing the socket of large-diameter flexible socket joint steel pipes, belonging to the field of pipeline engineering technology. For large-diameter steel pipes with integrated flared sockets, a ring-shaped reinforcing ring adapted to the socket is prepared and its ends are chamfered. The ring-shaped reinforcing ring is then coaxially positioned with the inner wall of the socket, achieving full circumferential fit. Subsequently, a full welding process is used to fix the reinforcing ring to the inner wall of the socket. Finally, a sealing positioning groove is formed between the reinforcing ring and the outer end anti-reverse ring of the socket, completing the socket reinforcement. The reinforcement method is simple and convenient to operate. The formed "socket-ring-reinforcing ring" composite structure significantly improves the radial stiffness of the socket, effectively suppressing circumferential deformation. Furthermore, the original flexible socket connection process of the steel pipe is not altered throughout the process, exhibiting strong compatibility. After reinforcement, it ensures uniform compression of the sealing rubber ring, preventing interface leakage. This method is suitable for the socket processing and reinforcement of large-diameter flexible socket joint steel pipes used in urban water supply, gas supply, and power plant circulating water systems.

Description

Technical Field

[0001] This invention relates to the field of pipeline engineering technology, and in particular to a method for reinforcing the socket of a large-diameter flexible socket joint steel pipe. Background Technology

[0002] Socket-joint flexible steel pipes have become the mainstream pipe material for large-diameter, long-distance pipeline projects due to their convenient installation and ability to adapt to axial expansion and radial deflection caused by geological settlement. The socket is typically integrally formed with the steel pipe body through hydraulic or mechanical flaring processes and is the core component of the socket connection. It must withstand multiple forces, including the pipeline's own weight, water pressure, backfill soil pressure, vehicle dynamic loads, as well as squeezing and collisions during transportation and external forces during on-site installation.

[0003] In existing technologies, the socket of large-diameter flexible joint steel pipes does not have a dedicated reinforcing structure, relying solely on its own wall thickness to ensure structural strength. However, the socket of large-diameter steel pipes has a large circumferential span and insufficient radial inherent stiffness. Under the aforementioned complex external forces, it is prone to circumferential deformation (ellipticity exceeding tolerance), which in turn leads to uneven circumferential compression of the sealing rubber ring, causing problems such as joint leakage and shortened rubber ring life. In severe cases, it can also cause difficulties in connecting the spigot and socket, reducing construction efficiency.

[0004] While some socket reinforcement methods exist in the industry, such as welding stiffening rings to the outside of the socket or adding secondary socket inserts, these methods are complex. External stiffening rings increase the pipe's outer diameter, affecting trench excavation and backfilling. Secondary socket inserts require altering the original flexible socket connection technology of the steel pipe, reducing the pipe's adaptability to geological settlement. Furthermore, they have long processing cycles and high manufacturing costs, making them unsuitable for the efficient construction requirements of engineering sites. Therefore, there is an urgent need for a socket reinforcement method for large-diameter flexible socket steel pipes that is simple to process, easy to operate, provides significant reinforcement, and does not alter the original flexible socket connection performance of the steel pipe. Summary of the Invention

[0005] The purpose of this invention is to propose a method for reinforcing the socket of a large-diameter flexible socket steel pipe to solve the problems mentioned in the background art. By adding an annular reinforcing ring to the inner wall of the socket, efficient reinforcement of the socket is achieved, significantly improving the radial stiffness of the socket and effectively suppressing circumferential deformation. Moreover, this method is simple in process, controllable in operation, does not change the original flexible socket connection process of the steel pipe, has strong compatibility, and can ensure the reliability of sealing after reinforcement.

[0006] To achieve the above objectives, this invention provides a method for reinforcing the socket of a large-diameter flexible socket steel pipe. The method involves setting an annular reinforcing ring on the inner wall of the socket at one end of the steel pipe body to form a composite reinforcement structure, comprising the following steps: Step S1: Prepare the annular reinforcing ring: Prepare the annular reinforcing ring according to the internal dimensions of the socket. The axial length of the annular reinforcing ring is consistent with the axial length inside the socket. The radial thickness is selected according to the diameter of the steel pipe body and the appropriate wall thickness is selected inside the socket. Step S2: Machining the annular reinforcing ring: Chamfering is performed on both end faces of the annular reinforcing ring, with a chamfer angle greater than 30° and less than 45°; Step S3: Coaxial positioning assembly: Place the machined annular reinforcing ring into the socket, so that the annular reinforcing ring is coaxially arranged with the socket, and the outer wall of the annular reinforcing ring is tightly fitted with the inner wall of the socket around the entire circumference. Step S4: Full welding fixation: The annular reinforcing ring is fixedly connected to the inner wall of the socket using a full welding process. Welds are set around the entire circumference of both ends of the annular reinforcing ring along the axial direction. The height of the weld is not less than the radial thickness of the annular reinforcing ring. Step S5: Forming a sealing positioning groove: Fix a backstop ring to the outer end of the socket to form a sealing positioning groove between the backstop ring and the end of the annular reinforcing ring.

[0007] Preferably, the steel pipe body is a spiral welded steel pipe, a straight seam welded steel pipe, or a seamless steel pipe, and the socket is integrally formed at the end of the steel pipe body by hydraulic flaring or mechanical flaring process.

[0008] Preferably, in step S1, the material strength of the annular reinforcing ring is not lower than the material strength of the steel pipe body and the socket.

[0009] Preferably, in step S3, a coaxial positioning fixture is used to position and assemble the annular reinforcing ring, the coaxiality error between the annular reinforcing ring and the socket is no more than 0.5mm, and there is no gap between the annular reinforcing ring and the inner wall of the socket.

[0010] Preferably, in step S4, the full welding process uses manual arc welding or gas shielded welding, and the weld is subjected to non-destructive testing after welding is completed.

[0011] Preferably, in step S5, the anti-reverse retaining ring is fixed to the outer end of the socket by welding, with its inner diameter being larger than the outer diameter of the steel pipe body and its outer diameter being consistent with the outer diameter of the socket.

[0012] Preferably, in step S5, the sealing rubber ring is installed into the sealing positioning groove so that the sealing rubber ring and the sealing positioning groove are interference fit.

[0013] Preferably, a sealed inner cavity is formed between the inner wall of the annular reinforcing ring and the outer diameter of the steel pipe body socket. After the sealing rubber ring is installed in the sealed inner cavity, a flexible seal is achieved through compression and rebound.

[0014] Therefore, the present invention employs the above-mentioned method for reinforcing the socket of a large-diameter flexible joint steel pipe, which has the following advantages: (1) Significant reinforcement effect and significantly improved socket deformation resistance: The annular reinforcing ring fits and is coaxially fixed with the inner wall of the socket around the entire circumference, forming a "socket-annular reinforcing ring" composite structure, which greatly improves the radial stiffness of the socket and effectively controls the ellipticity of the socket. It can effectively resist the circumferential deformation caused by transportation, backfill soil and vehicle external loads, water pressure fluctuations or self-weight, and fundamentally solve the technical problem of easy circumferential deformation of the socket. (2) Ensure sealing reliability: This method ensures the coaxiality of the reinforcing ring and the socket by using coaxial positioning fixtures, and ensures the quality of the weld by non-destructive testing. The reinforcement structure has high stability and consistency. Moreover, the socket is not deformed after reinforcement, which can ensure that the compression of the sealing rubber ring in the circumferential direction is uniform, avoid local stress concentration, completely solve the risk of interface leakage caused by socket deformation, and extend the service life of the sealing rubber ring. (3) Strong compatibility: The reinforcing structure of this method is located inside the socket, and the original flexible connection process of the steel pipe is not changed throughout the process. The axial expansion and contraction and deflection angle of the socket are not affected. It can be adapted to existing flexible interface forms such as sliding type and mechanical type, without the need to adjust the installation equipment and process. (4) Simple structure and low cost: The manufacturing process of the ring reinforcement ring is simple and the welding and fixing method with the socket is mature. Compared with the external reinforcement or secondary socket welding scheme, it significantly reduces the manufacturing cost and construction cycle, and subsequent maintenance is convenient.

[0015] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0016] Figure 1 This is a structural schematic diagram of a method for reinforcing the socket of a large-diameter flexible joint steel pipe mentioned in an embodiment of the present invention; Figure 2 This is a flowchart illustrating the steps of a method for reinforcing the socket of a large-diameter flexible joint steel pipe mentioned in an embodiment of the present invention.

[0017] Figure label: 1. Steel pipe body; 2. Socket; 3. Annular reinforcing ring; 4. Anti-reverse retaining ring; 5. Weld; 6. Sealing positioning groove; 7. Sealing rubber ring; 8. Steel pipe body spigot. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the 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.

[0019] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0020] Example like Figure 1-2 As shown, this embodiment provides a method for reinforcing the socket of a large-diameter flexible joint steel pipe. For a large-diameter steel pipe body 1 integrally formed with a socket 2 through a flaring process, an annular reinforcing ring 3 adapted to the socket 2 is added to the inner wall of the socket 2, forming a composite load-bearing structure of "socket 2 - annular reinforcing ring 3". This achieves deformation resistance reinforcement of the socket 2. The steel pipe body 1 is a spiral welded steel pipe, a straight seam welded steel pipe, or a seamless steel pipe. The socket 2 can be integrally formed at the end of the steel pipe body 1 through hydraulic or mechanical flaring processes, without requiring modification to the original structure of the steel pipe body 1 and the socket 2, thus exhibiting strong adaptability. Specifically, the method includes the following steps: S1. Preparation of the annular reinforcing ring 3: Based on the actual internal dimensions of the socket 2 to be reinforced, the annular reinforcing ring 3 is custom-made. The steel pipe body 1 is any large-diameter steel pipe with a nominal diameter of not less than DN600. The annular reinforcing ring 3 is made of steel with a strength grade of Q235B or higher, and its material strength is not lower than that of the steel pipe body 1 and the socket 2, ensuring that the reinforcing ring and the socket 2 are subjected to force synchronously and deform together. The axial length of the annular reinforcing ring 3 is completely consistent with the internal axial length of the socket 2, and the radial thickness is greater than the wall thickness of the socket 2, providing sufficient radial support for the socket 2. At the same time, it is ensured that the inner wall of the annular reinforcing ring 3 and the inner wall of the steel pipe body 1 can achieve a smooth transition without protruding steps, avoiding flow resistance during media transportation.

[0021] S2. Processing the annular reinforcing ring 3: Chamfers are processed on both ends of the annular reinforcing ring 3, with the chamfer angle controlled at 30°~45°. This chamfer facilitates the full deposition of welding materials during subsequent welding, ensuring the forming quality and welding strength of the weld 5. On the other hand, it effectively avoids the sealing positioning groove 6, preventing the welding operation from affecting the dimensional accuracy of the sealing positioning groove 6. At the same time, an avoidance notch is processed on the outer wall of the annular reinforcing ring 3 at the position of the pre-set sealing positioning groove 6 on the inner wall of the socket 2. The size and shape of the avoidance notch are completely adapted to the sealing positioning groove 6 on the inner wall of the socket 2, ensuring that the sealing rubber ring 7 can be installed normally afterward.

[0022] S3. Coaxial positioning assembly: Place the machined annular reinforcing ring 3 into the socket 2 to be reinforced, and use a special coaxial positioning fixture for positioning to ensure that the annular reinforcing ring 3 and the socket 2 are coaxially arranged with a coaxiality error of no more than 0.5mm; and adjust the position of the annular reinforcing ring 3 so that the outer wall of the annular reinforcing ring 3 and the inner wall of the socket 2 are tightly fitted around the entire circumference without gaps between them, ensuring that the reinforcing ring can evenly bear the circumferential stress of the socket 2 and avoid local stress concentration.

[0023] S4. Full Weld Fixing: The annular reinforcing ring 3 is fixedly connected to the inner wall of the socket 2 using a full welding process. During welding, full circumference welding is performed at both ends of the annular reinforcing ring 3 along the axial direction to form a continuous weld 5. The height of the weld 5 is not less than the radial thickness of the annular reinforcing ring 3 to ensure the strength of the welded connection and prevent the annular reinforcing ring 3 from falling off or loosening under external loads. The welding process can be manual arc welding or gas shielded welding to adapt to the operational requirements of different construction scenarios. After welding, the weld 5 is subjected to non-destructive testing to ensure that the weld 5 is free of defects such as slag inclusions, porosity, and incomplete penetration, thus ensuring the reliability of the reinforcing structure.

[0024] S5. Forming a sealing positioning groove 6: Weld and fix a backstop ring 4 to the outer end of the socket 2. The inner diameter of the backstop ring 4 is larger than the outer diameter of the steel pipe body 1, and the outer diameter is consistent with the outer diameter of the socket 2, so that a regular annular sealing positioning groove 6 is formed between the backstop ring 4 and the end of the annular reinforcing ring 3. The sealing positioning groove 6 provides positioning and accommodation space for the subsequent installation of the sealing rubber ring 7, thus completing all the reinforcement work of the socket 2.

[0025] The sealing rubber ring 7 is installed into the formed sealing positioning groove 6, so that the sealing rubber ring 7 and the sealing positioning groove 6 are interference fit, and the initial positioning of the sealing rubber ring 7 is achieved. When the spigot of the adjacent steel pipe is inserted into the reinforced socket 2, the inner wall of the annular reinforcing ring 3 and the outer diameter of the steel pipe spigot 8 form a sealing cavity. After the sealing rubber ring 7 is squeezed into the sealing cavity, it undergoes elastic deformation. Through the compression rebound force, the outer wall of the sealing rubber ring 7 is tightly fitted with the inner wall of the annular reinforcing ring 3, and the inner wall is tightly fitted with the outer wall of the steel pipe spigot 8, so as to achieve a flexible seal of the socket interface.

[0026] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for reinforcing the socket of a large-diameter flexible socket joint steel pipe, characterized in that: A composite reinforcement structure is formed by setting an annular reinforcing ring on the inner wall of the socket at one end of the steel pipe body. The steel pipe body is a spiral welded steel pipe, a straight seam welded steel pipe, or a seamless steel pipe. The socket is integrally formed at the end of the steel pipe body by hydraulic flaring or mechanical flaring process. The process includes the following steps: Step S1: Prepare the annular reinforcing ring: Prepare the annular reinforcing ring according to the internal dimensions of the socket. The axial length of the annular reinforcing ring is consistent with the axial length inside the socket. The radial thickness is selected according to the diameter of the steel pipe body and the appropriate wall thickness is selected inside the socket. Step S2: Machining the annular reinforcing ring: Chamfering is performed on both end faces of the annular reinforcing ring, with a chamfer angle greater than 30° and less than 45°; Step S3: Coaxial positioning assembly: Place the machined annular reinforcing ring into the socket, so that the annular reinforcing ring is coaxially arranged with the socket, and the outer wall of the annular reinforcing ring is tightly fitted with the inner wall of the socket around the entire circumference. The annular reinforcing ring is positioned and assembled using a coaxial positioning fixture. The coaxiality error between the annular reinforcing ring and the socket is no more than 0.5mm, and there is no gap between the annular reinforcing ring and the inner wall of the socket. Step S4: Full welding fixation: The annular reinforcing ring is fixedly connected to the inner wall of the socket using a full welding process. Welds are set around the entire circumference of both ends of the annular reinforcing ring along the axial direction. The height of the weld is not less than the radial thickness of the annular reinforcing ring. Step S5: Forming a sealing positioning groove: A backstop ring is fixedly installed at the outer end of the socket. The backstop ring is fixed to the outer end of the socket by welding. Its inner diameter is larger than the outer diameter of the steel pipe body, and its outer diameter is consistent with the outer diameter of the socket, so that a sealing positioning groove is formed between the end of the backstop ring and the annular reinforcing ring. Install the sealing rubber ring into the sealing positioning groove so that the sealing rubber ring and the sealing positioning groove are interference fit; The inner wall of the annular reinforcing ring forms a sealed inner cavity with the outer diameter of the steel pipe body socket. After the sealing rubber ring is installed in the sealed inner cavity, it achieves a flexible seal through compression and rebound.

2. The method for reinforcing the socket of a large-diameter flexible socket joint steel pipe according to claim 1, characterized in that: In step S1, the material strength of the annular reinforcing ring shall not be lower than the material strength of the steel pipe body and the socket.

3. The method for reinforcing the socket of a large-diameter flexible socket joint steel pipe according to claim 1, characterized in that: In step S4, the full welding process is either manual arc welding or gas shielded welding. After welding is completed, the weld is subjected to non-destructive testing.

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