Large-diameter composite bent pipe

Abstract

The utility model relates to the technical field of pipelines, in particular to a large-diameter composite bent pipe. Comprising an outer bent pipe; the inner bent pipe and the outer bent pipe are coaxially arranged, and the inner side of the outer bent pipe is sleeved with the inner bent pipe; the inner bent pipe is formed by sequentially connecting a plurality of pipe joints. The outer bent pipe is an integrally-formed seamless bent pipe. The outer bent pipe is made of carbon steel. The pipe joint is of a closed cylindrical structure formed by rolling plates and then butt-jointing the plates. The pipe joints are made of stainless steel materials. The pipe joints located at the two ends are fixedly connected with the outer bent pipe through spot welding. Chamfers are arranged on the edges of the inner sides of the connectors at the two ends of the pipe joints, and the adjacent pipe joints are connected in a welded mode through grooves formed by folding the chamfers. The structural strength and durability can be remarkably improved, and meanwhile the manufacturing cost is effectively reduced.

Description

Technical Field

[0001] This utility model relates to the field of pipeline technology, specifically to a large-diameter composite bend. Background Technology

[0002] In pipeline transportation systems, large-diameter bends are key components for achieving directional transport of fluid media. These operating conditions typically place high demands on the bend's pressure-bearing capacity, wear resistance, corrosion resistance, and service life.

[0003] In existing technologies, the following solutions are mainly used to meet these requirements for large-diameter bends:

[0004] 1. Seamless Stainless Steel Bend: To meet corrosion resistance requirements, large-diameter seamless bends are made directly from a single piece of stainless steel through processes such as hot pushing and extrusion. However, this approach has significant drawbacks: First, the forming process for large-diameter, thick-walled seamless stainless steel bends is extremely difficult, resulting in extremely high finished product prices and significantly increasing project construction costs; second, the strength of stainless steel is generally lower than that of carbon steel of the same specifications, potentially requiring thicker walls to withstand high pressure, further increasing material costs and manufacturing difficulty.

[0005] 2. Integral carbon steel bend with anti-corrosion lining: To reduce costs, relatively inexpensive carbon steel is used to manufacture the integral bend, and an anti-corrosion coating or lining is applied to its inner wall. The drawback of this approach is that the anti-corrosion coating is easily damaged under the scouring of high-speed fluids containing particles. Once damaged, localized corrosion will accelerate, and maintenance and repair will be difficult, making it hard to guarantee the overall service life.

[0006] 3. Composite Bending Structure: Some existing technologies also employ composite bending structures, attempting to balance structural strength and inner wall corrosion resistance. However, traditional composite structures often fix the inner liner and outer bending pipe as a whole. This leads to significant thermal stress under thermal expansion and contraction conditions due to the difference in thermal expansion coefficients between the inner and outer layers, posing a risk of interface failure. Furthermore, when only the internal corrosion-resistant layer needs replacement, traditional structures often make localized repairs difficult, typically requiring the replacement of the entire bending pipe, resulting in high maintenance costs.

[0007] In summary, existing large-diameter pipe bending solutions struggle to simultaneously guarantee excellent corrosion resistance and structural strength while also ensuring cost-effectiveness in manufacturing, feasibility in producing large components, and ease of maintenance and replacement. Therefore, a novel large-diameter pipe bending design is needed to address these technical challenges. Utility Model Content

[0008] In order to solve the technical problems existing in the background art, the present invention provides a large-diameter composite bend pipe, which can significantly improve the structural strength and durability, while effectively reducing the manufacturing cost.

[0009] The technical solution adopted by this utility model to solve its technical problem is:

[0010] A large-diameter composite bend, comprising:

[0011] External bend;

[0012] The inner bend is coaxially arranged with the outer bend and is sleeved on the inner side of the outer bend;

[0013] An internal bend is formed by connecting several pipe sections in sequence.

[0014] Furthermore, the outer bend is made of a seamless, one-piece molded pipe.

[0015] Furthermore, the outer bend is made of carbon steel.

[0016] Furthermore, the tube section is a closed cylindrical structure formed by the butt jointing of sheet metal after rolling.

[0017] Furthermore, the pipe sections are made of stainless steel.

[0018] Furthermore, the pipe sections at both ends are fixedly connected to the outer bend pipe by spot welding.

[0019] Furthermore, the inner edges of the interfaces at both ends of the pipe section are chamfered, and adjacent pipe sections are welded together by the bevel formed by the matching chamfers.

[0020] The beneficial effects of this utility model are:

[0021] (1) The outer bend adopts an integrally formed seamless bend structure, which eliminates potential weak points in the weld and significantly improves the pressure-bearing capacity and fatigue resistance of the bend, making it suitable for high-pressure and high-stress conditions. Meanwhile, the inner bend is made of stainless steel pipe sections, which enhances the corrosion resistance and wear resistance of the inner wall and extends the service life of the bend, making it particularly suitable for conveying corrosive media or abrasive fluids.

[0022] (2) The inner bend is made by joining multiple pipe sections together after rolling the sheet metal. This segmented manufacturing method reduces the processing difficulty and equipment requirements of large-diameter bends, facilitates standardized production, and reduces raw material waste. The outer bend is made of carbon steel, which has a lower cost, while the inner bend only needs to use stainless steel for the key inner wall, which achieves a reasonable allocation of material costs and better overall economic efficiency.

[0023] (3) The inner bend is located inside the outer bend and is fixed to the outer bend by spot welding at both ends of the pipe sections. This connection method ensures the coaxiality and relative positional stability between the inner and outer pipes, while allowing for a certain degree of thermal expansion adaptability, thus avoiding stress concentration caused by temperature changes. Spot welding simplifies the assembly process and facilitates on-site installation and adjustment.

[0024] (4) A chamfer is set on the inner edge of the pipe section interface. Adjacent pipe sections are welded by the bevel formed by the chamfer, which makes the weld penetration more uniform, reduces welding defects, and improves the strength and sealing of the connection. At the same time, bevel welding helps to disperse stress, reduce the risk of cracking, and ensure the integrity of the inner bend in long-term use. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] Figure 1 This is a schematic diagram of the structure of this utility model;

[0027] Figure 2 This is a schematic diagram of the inner tube structure;

[0028] Figure 3 This is a schematic diagram of the pipe section.

[0029] In the picture:

[0030] 1. Outer bend, 2. Inner bend;

[0031] 21. Pipe section;

[0032] 211. Interface. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to the accompanying drawings.

[0034] like Figure 1 , 2 As shown, a large-diameter composite bend pipe has the following specific structure: an outer bend pipe 1. An inner bend pipe 2 is coaxially arranged with the outer bend pipe 1 and is sleeved inside the outer bend pipe 1. The inner bend pipe 2 is composed of several pipe sections 21 connected sequentially.

[0035] In terms of material composition, the outer bend 1 is a seamless bend formed in one piece, and the outer bend 1 is made of carbon steel. The pipe section 21 is a closed cylindrical structure formed by butt jointing of sheet metal after rolling, and the pipe section 21 is made of stainless steel.

[0036] The outer bend 1 adopts a one-piece seamless bend structure, eliminating potential weak points in the weld and significantly improving the pressure-bearing capacity and fatigue resistance of the bend, making it suitable for high-pressure and high-stress conditions. Meanwhile, the inner bend 2 is composed of stainless steel pipe sections, enhancing the corrosion resistance and wear resistance of the inner wall and extending the service life of the bend, making it particularly suitable for conveying corrosive media or abrasive fluids.

[0037] The inner bend 2 is formed by joining multiple pipe sections 21 together after rolling sheet metal. This segmented manufacturing method reduces the processing difficulty and equipment requirements of large-diameter bends, facilitates standardized production, and reduces raw material waste. The outer bend 1 is made of carbon steel, which has a lower cost, while the inner bend 2 only needs to use stainless steel for the key inner wall, achieving a reasonable allocation of material costs and better overall economic efficiency.

[0038] Regarding the connection structure, the pipe sections 21 at both ends are fixedly connected to the outer bend 1 by spot welding. For example... Figure 3 As shown, the inner edges of the interfaces 211 at both ends of the pipe section 21 are chamfered, and adjacent pipe sections 21 are welded together by the bevel formed by the chamfers.

[0039] The inner bend 2 is located inside the outer bend 1 and is fixed to the outer bend 1 by spot welding through pipe sections 21 at both ends. This connection method ensures the coaxiality and relative positional stability between the inner and outer pipes, while allowing for a certain degree of thermal expansion adaptability, thus avoiding stress concentration caused by temperature changes. Spot welding simplifies the assembly process and facilitates on-site installation and adjustment.

[0040] The inner edge of the interface 211 of pipe section 21 is chamfered. Adjacent pipe sections 21 are welded by the bevel formed by the chamfer, which makes the weld penetration more uniform, reduces welding defects, and improves the strength and sealing of the connection. At the same time, bevel welding helps to disperse stress, reduce the risk of cracking, and ensure the integrity of the inner bend during long-term use.

[0041] In a specific embodiment, the outer side of the bend section of the inner bend 2 experiences stronger impact during operation, while the inner side experiences relatively weaker impact. To accommodate this difference in stress, the interface 211 located on the outer side of the bend section of the inner bend 2 employs a larger chamfer size, resulting in a larger weld and thus improving the welding strength at that location. Conversely, the interface 211 located on the inner side of the bend section of the inner bend 2 employs a smaller chamfer size, resulting in a smaller weld and relatively lower welding strength.

[0042] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A large-diameter composite bend, characterized in that, include: External bend (1); The inner bend (2) is coaxially arranged with the outer bend (1) and sleeved on the inner side of the outer bend (1); The inner bend (2) is composed of several pipe sections (21) connected in sequence.

2. The large-diameter composite bend according to claim 1, characterized in that, The outer bend (1) is a seamless bend formed in one piece.

3. A large-diameter composite bend according to claim 2, characterized in that, The outer bend (1) is made of carbon steel.

4. A large-diameter composite bend according to claim 1, characterized in that, The tube section (21) is a closed cylindrical structure formed by joining together rolled sheet metal.

5. A large-diameter composite bend according to claim 4, characterized in that, The pipe section (21) is made of stainless steel.

6. A large-diameter composite bend according to claim 1, characterized in that, The pipe sections (21) located at both ends are fixedly connected to the outer bend (1) by spot welding.

7. A large-diameter composite bend according to claim 1, characterized in that, The inner edges of the interfaces (211) at both ends of the pipe section (21) are chamfered, and adjacent pipe sections (21) are welded together by fitting the bevel formed by the chamfer.

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