Device and method for protecting U-shaped bend pipe

Abstract

The invention relates to a device and a method for protecting a U-shaped bent pipe, and belongs to the technical field of heating pipeline engineering. The purpose is to reduce the difficulty of the protection construction of the U-shaped bent pipe and improve its applicability. The technical scheme is that a water supply pipe and a water return pipe laid in parallel to bypass an obstacle form a U-shaped pipeline, the water supply pipe is located between the water return pipe and the obstacle, an arc steel is fixedly connected to both ends of the U-shaped structure of the water supply pipe, the arc steel and the U-shaped structure of the water supply pipe are respectively located on both sides of the obstacle, and the arc steel and the water supply pipe are located in the same horizontal plane; the arc steel offsets the force applied to the pipeline. Compared with the prior art, the device of the invention has a simple structure and flexible layout; reduces the difficulty of protection construction, and is adaptable to various obstacle environments.

Description

Technical Field

[0001] The invention belongs to the technical field of heating pipeline engineering, and specifically relates to a device and method for protecting a U-shaped bent pipe. Background Art

[0002] The following situations are often encountered in the design and construction of direct buried heating pipelines: During the process of locating the pipeline network, obstacles such as trees or electric poles often block the direction of pipeline laying. When the space around the obstacles is not large enough and square compensators cannot be installed, how to safely bypass these obstacles becomes a problem that designers need to consider.

[0003] The first existing technical solution is to bypass obstacles by connecting small corners in series, such as Figure 1 As shown. There are no fixed piers or compensators on both sides of the angle, or there is no compensation pipe section far away from the compensation device. In order to prevent fatigue damage and local wrinkles, the angle should not be greater than the maximum allowable angle Ø max,n . Maximum allowable angle Ø for various pipe diameters and temperature differences max,n Due to the small allowable angle, the number of corners is very large, the construction is difficult and the distance involved is long; each corner is also a stress danger point, which reduces the safety of the pipeline. In addition, this technical solution cannot solve sudden obstacles.

[0004] The second existing technical solution is to bypass the obstacle by making a U-shaped bend, and then set compensators on both sides of the U-shaped bend to protect it. Figure 2 As shown. The compensator should be consistent with the pipeline axial direction, and the distance between the axial compensator and the elbow should be greater than or equal to 1.5Le; the distance between the fixed pier and the elbow should be 1Le. The lengths of L1, L2, and L3 in the figure are determined by the size of the obstacle and other surrounding pipe positions. Because the lengths of L1, L2, and L3 need to pass stress verification. When the installation conditions are not met and the strength conditions cannot be met, the solution is not feasible; Solution 2 adds a compensator and an inspection chamber, which not only increases investment, but also increases the probability of compensator leakage and reduces the safety of the pipeline network; when using technical solution 2 to solve sudden obstacles, it will cause construction rework and extend the construction period, especially in winter.

[0005] The third existing technical solution is to bypass the obstacle by making a U-shaped bend pipe, and then set fixed piers on both sides of the U-shaped bend pipe to protect it. Figure 3As shown. This solution is also because the lengths of L1, L2, and L3 need to pass stress calculation. The solution is not feasible when the installation conditions are not met and the strength conditions cannot be met. The fixed pier design requires designers to provide thrust and complete civil engineering design, and have geological conditions for construction. Solution three adds fixed piers and increases investment. The thrust of the fixed piers for direct buried pipelines generally ranges from tens of tons to hundreds of tons, and the volume is large. It cannot be implemented when the area around the pipeline is narrow. When using technical solution three to solve sudden obstacles, it will cause construction rework and extend the construction period, especially during winter construction. Summary of the invention

[0006] The present invention overcomes the shortcomings of the prior art and provides a device and method for protecting a U-shaped bend pipe, the purpose of which is to reduce the difficulty of the protection construction of the U-shaped bend pipe and improve its applicability.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions.

[0008] A device for protecting a U-shaped bend pipe, wherein the U-shaped bend pipe is used to form a U-shaped pipeline for bypassing an obstacle, wherein the U-shaped pipeline includes a water supply pipe and a water return pipe laid in parallel, and the plane where the obstacle is located is perpendicular to the water supply pipe and the water return pipe; the water supply pipe is located between the water return pipe and the obstacle, and an arc steel is fixedly connected to both ends of the U-shaped structure of the water supply pipe, the arc steel and the U-shaped structure of the water supply pipe are respectively located on both sides of the obstacle, the arc steel and the water supply pipe are located in the same horizontal plane, and the arc steel and the U-shaped pipeline are coaxially symmetrical.

[0009] Furthermore, the return pipe is located between the water supply pipe and the obstacle, and the two ends of the U-shaped structure of the return pipe and the water supply pipe are connected respectively by pipe clamps and fixing steel, and the two ends of the arc steel are fixedly connected to the two ends of the U-shaped structure of the return pipe.

[0010] Furthermore, a passivation film is provided on the outside of the pipe clamp and the fixing steel.

[0011] Furthermore, the plane where the obstacle is located is parallel to the water supply pipe and the water return pipe, and the arc steel is arranged perpendicular to the water supply pipe and the water return pipe.

[0012] Furthermore, both ends of the U-shaped structure of the return pipe and the water supply pipe are connected by multiple sets of pipe clamps and fixing steel.

[0013] Furthermore, the arc steel is welded to both ends of the U-shaped structure of the water supply pipe.

[0014] Furthermore, a passivation film is provided on the outside of the arc steel.

[0015] Furthermore, a plurality of arc-shaped steels are provided.

[0016] Furthermore, the arc steel is any one of I-beam, channel steel, U-shaped steel and H-steel.

[0017] A U-shaped bend pipe protection method, wherein the U-shaped bend pipe is used to bypass an obstacle to form a U-shaped pipeline, the pipeline includes a water supply pipe and a water return pipe laid in parallel, and the plane where the obstacle is located is perpendicular to the water supply pipe and the water return pipe; two ends of an arc steel are welded to the two ends of the U-shaped structure of the water supply pipe, or the return pipe and the two ends of the U-shaped structure of the water supply pipe are connected respectively through a pipe clamp and a fixing steel and then the two ends of the arc steel are welded to the two ends of the U-shaped structure of the return pipe, the arc steel and the U-shaped pipeline are respectively located on both sides of the obstacle, the arc steel and the U-shaped pipeline are located in the same horizontal plane, and the arc steel and the U-shaped pipeline are coaxially symmetrical.

[0018] Since the temperature of the water supply pipe is much higher than that of the return pipe, the U-shaped bend on the water supply pipe needs to be protected. When the water supply pipe is close to the obstacle, the arc steel is directly welded to the water supply pipe, such as Figure 4 As shown; when the water supply pipe is on the side away from the obstacle, since the arc steel is arranged on the outside, it takes up a large space and the compensation effect is weaker than that on the inside, the supply and return pipes are fixed together by pipe clamps and fixing steel, and the arc steel is welded to the return pipe, as shown in Figure 5 To make the connection between the water supply and return pipes more stable, two fixed steel bars can be arranged on both sides of the U-shaped bend. The cross-sectional diagram of the fixed connection between the water supply and return pipes is shown in the figure below. Figure 6 shown.

[0019] When the arc steel is directly welded to the water supply pipe, the force diagram of the arc steel is as follows Figure 7 Assume that the pipeline is not welded with arc steel, and point H is fixed when the pipeline is running. According to the force analysis of fixed piers in the "Direct Buried Heating Pipeline Engineering Design", the thrust on point H can be calculated in the following two cases:

[0020] Figure 7 L1 is the distance from point H to the end of the U-bend, and L2 is the distance from point H to the active end of the U-bend;

[0021] L1≧L min , L1≧L2, and L max >L2

[0022] H=N a1 -0.8(F min L2+P t2 )

[0023] Where N a1 =F min L max +P t1

[0024] N a1 is the axial force at the left end of point H, L min is the minimum transition length, Lmax is the maximum transition length, P t1 , P t2 It is the resistance of the movable end to the expansion and contraction of the pipe.

[0025] (2) L min >L1>L2

[0026] H=(F max L1+P t1 )-0.8(F min L2+P t2 )

[0027] After adding the arc steel, the force of the arc steel on the pipeline can be decomposed into the axial force F1 and the radial force F2 along the pipeline. The U-shaped tube is symmetrical on both sides. The forces along the axial direction of the pipeline on the left and right sides of the arc steel can offset each other, and the force perpendicular to the axial direction of the pipeline can offset the elastic reaction force of the soil.

[0028] When the arc steel is welded to the return pipe, the axial force of the supply pipe is transmitted to the return pipe through the fixing steel, and the thrust direction of the supply and return pipes on the arc steel is also the same. Figure 7 shown.

[0029] The arc steel bears the thrust of the pipeline: F1=H; F2 is offset by the constraint force of the soil and the axial internal force of the AB section.

[0030] Figure 7 The relative position of the middle arc steel and the heating pipe can be determined according to the specific position and size of the obstacle. The smaller θ is, the larger F1 is when F is the same, and the greater the axial thrust of the pipe that the arc steel can withstand.

[0031] In order to avoid damage to the fixed knot during operation, the fixed knot can be reinforced by rib reinforcement.

[0032] Metals buried directly in the soil are prone to corrosion. They can be treated with passivators or film-forming agents to form a stable passivation film on the surface, or they can be painted or protected by electrochemical protection methods.

[0033] The beneficial effects of the present invention compared with the prior art are as follows: Compared with other technical solutions, the method of using arc steel has a simple structure and flexible arrangement.

[0034] Compared with technical solution 1, this technical solution does not have many stress danger points, involves a short distance, has low construction difficulty and improved safety, and overcomes the problem of difficult to solve sudden obstacles.

[0035] Compared with Technical Solution 2, this technical solution has relatively loose construction and installation conditions, a wider range of applicable U-shaped pipe sizes, and no need to install a compensator inspection chamber. The project cost is reduced, the safety of the pipeline is improved, and the solution to sudden obstacles is more flexible.

[0036] Compared with Technical Solution 3, this technical solution does not require the installation of large-volume fixed piers, the requirements for construction conditions are greatly reduced, the applicable U-shaped pipe size range is wider, and it will not affect the design, construction and surrounding building planning of other pipelines, and it is also simpler to solve sudden obstacles.

[0037] Arc steel can be prefabricated and serialized in factories according to the radius of curvature, size, etc. It has high welding quality and is easy to select. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of a prior art solution 1;

[0039] Figure 2 This is a schematic diagram of the second prior art solution;

[0040] Figure 3 It is a schematic diagram of the third prior art solution;

[0041] Figure 4 This is a layout diagram of the embodiment 1 of the protection U-shaped elbow structure of the present invention;

[0042] Figure 5 This is a layout diagram of the second embodiment of the U-shaped bend pipe protection structure of the present invention;

[0043] Figure 6 for Figure 5 Schematic diagram of cross section of fixed connection of water supply and return pipes;

[0044] Figure 7 It is the schematic diagram of the arc steel force;

[0045] Among them, 1 is an obstacle, 2 is a water supply pipe, 3 is a return pipe, 4 is arc steel, 5 is a pipe clamp, 6 is a fixing steel, 7 is a compensator, and 8 is a fixed pier. DETAILED DESCRIPTION

[0046] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention is further described in detail in conjunction with the embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. The technical solutions of the present invention are described in detail below in conjunction with the embodiments and the accompanying drawings, but the scope of protection is not limited thereto.

[0047] Example 1

[0048] like Figure 4As shown in the figure, it is a branch of a direct buried heating pipe network primary network project in Taiyuan, Shanxi. The design water supply temperature is 120℃, the return water temperature is 70℃, the installation temperature is 10℃, the minimum working cycle temperature is 10℃, the pipeline burial depth is 1.2 meters, the design pressure is 1.6MPa, and the DN500 pipeline hits the obstacle pole. The pipeline direction is as follows Figure 4 As shown, the pipeline forms a U-shaped pipeline bypassing the obstacle 1 at the place where it encounters the obstacle. The pipeline includes a water supply pipe 2 and a water return pipe 3 laid in parallel. The water supply pipe 2 is located between the water return pipe 3 and the obstacle 1. An arc steel 4 is welded at both ends of the U-shaped structure of the water supply pipe 2. The arc steel 4 and the U-shaped structure of the water supply pipe 2 are located on both sides of the obstacle 1 respectively. The arc steel 4 and the water supply pipe 2 are located in the same horizontal plane. A passivating agent is used to form a passivation film on the outside of the arc steel 4.

[0049] When the arc steel 4 is welded to both sides of the U-shaped bend of the water supply pipe 2 through the fixed joint, the force diagram of the arc steel 4 is as follows: Figure 7 As shown in the figure, the distance between the arc steel welding point and the elbow is 3 meters. Figure 7 L1 is the distance from point H to the end of the U-bend, L2 is the distance from point H to the active end of the U-bend, L1=57 meters, L2=3 meters. Assuming that the pipeline is not welded with arc steel, point H is fixed during the operation of the pipeline, and the force on the welding point H along the axial direction of the pipeline is:

[0050] H=(F max L1+P t1 )-0.8(F min L2+P t2 )

[0051] =7786×2×57-0.8×(7786×3)

[0052] =869KN

[0053] After adding the arc steel 4, the force of the arc steel on the pipeline can be decomposed into the force F1 along the pipeline axis and the radial force F2. The U-shaped tube is symmetrical on both sides. The forces along the pipeline axis on the left and right sides of the arc steel can offset each other, and the force perpendicular to the pipeline axis can offset the elastic reaction force of the soil.

[0054] In comparison:

[0055] 1. If the existing technical solution 1 is adopted, according to Appendix 8-1 of the "Design of Direct Buried Heating Pipeline Engineering", under the condition of single-seam welding, the maximum allowable angle of the DN500 pipeline without protection measures is 1.3°. According to the actual situation, 16 1.3° angles need to be connected in series so that the pipeline can avoid obstacles.

[0056] 2. If the existing technical solution 2 is adopted, according to Table 7-1 of the Design of Direct Buried Heating Pipe Engineering, the elastic arm length Le of the DN500 pipe is 8.2 meters, and the length of the U-shaped compensation elbow is 0.8 to 2 times the elastic arm length. The U-shaped elbow cannot be used as a compensation elbow. According to the use requirements of the sleeve compensator, the distance from the elbow must be greater than 1.5 times the elastic arm length, that is, greater than 12.3 meters. The compensation amount of the sleeve compensator is 87mm, and two compensator chambers with a size of approximately 2.4m×3m×1.8m are required for easy maintenance.

[0057] 3. If the existing technical solution 3 is adopted, the U-shaped elbow cannot be used as a compensation elbow, and a fixed pier is set to protect it. The distance between the fixed pier and the elbow is 3 meters. L1 = 57 meters, L2 = 3 meters, check Appendix 5-6, the maximum length of the transition section L max =376 meters, minimum length of transition section L min =L max / 2=188 meters, which belongs to the second case L min >L1>L2, since the compression reaction force of the soil on the elbow side is very small compared to the soil friction force and can be ignored, the force on the fixed pier along the pipeline axis is:

[0058] H=(F max L1+P t1 )-0.8(F min L2+P t2 )

[0059] =7786×2×57-0.8×(7786×3)

[0060] =869KN

[0061] The distance between the fixed pier and the elbow is less than the length of the elastic arm, but the elbow arm is only 3 meters long, so the thrust of the elbow axial force on the fixed pier in the direction perpendicular to the pipeline axis has been balanced by the soil. Therefore, the lateral force on the fixed pier is almost zero.

[0062] According to the magnitude of the force, if a T-shaped fixed pier is set, the floor area of ​​the fixed pier should be set to 5600mm×3200mm, and the height should be 2.5m+1.5m.

[0063] Example 2

[0064] like Figure 5 and 6 As shown in the figure, it is a branch of a direct buried heating pipe network primary network project in Taiyuan, Shanxi. The design water supply temperature is 120℃, the return water temperature is 70℃, the installation temperature is 10℃, the minimum working cycle temperature is 10℃, the pipeline burial depth is 1.2 meters, the design pressure is 1.6MPa, and the DN500 pipeline hits the obstacle pole. The pipeline direction is as follows Figure 5As shown, the pipeline forms a U-shaped pipeline that bypasses the obstacle 1 at the place where it encounters an obstacle. The pipeline includes a water supply pipe 2 and a return pipe 3 laid in parallel. The return pipe 3 is located between the water supply pipe 2 and the obstacle 1. The two ends of the U-shaped structure of the return pipe 3 and the water supply pipe 2 are connected by two sets of pipe clamps 5 and fixed steel 6 respectively. The two ends of the arc steel 4 are welded to the two ends of the U-shaped structure of the return pipe 3. The arc steel 4 and the U-shaped structure of the water supply pipe 2 are located on both sides of the obstacle 1 respectively, and the arc steel 4 and the water supply pipe 2 are located in the same horizontal plane. A passivating agent is used to form a passivation film on the outside of the arc steel 4, the pipe clamp 5 and the fixed steel 6.

[0065] Compared with the existing technical solutions, the construction and installation conditions of this device are relatively loose, and the applicable U-shaped pipe size range is larger, which reduces the project cost, improves the safety of the pipeline, and is more flexible in solving sudden obstacles; and the arc steel can be prefabricated and serialized in the factory according to the curvature radius, size, etc., with high welding quality and easy selection.

[0066] The above content is a further detailed description of the present invention in combination with a specific preferred embodiment. It cannot be determined that the specific embodiments of the present invention are limited to this. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the present invention, which should be regarded as belonging to the present invention and the scope of patent protection determined by the submitted claims.

Claims

1. A device for protecting a U-shaped bend pipe, wherein the U-shaped bend pipe is used to bypass an obstacle (1) to form a U-shaped pipeline, wherein the U-shaped pipeline comprises a water supply pipe (2) and a water return pipe (3) laid in parallel, and the plane where the obstacle (1) is located is perpendicular to the water supply pipe (2) and the water return pipe (3); characterized in that: The water supply pipe (2) is located between the water return pipe (3) and the obstacle (1), and an arc-shaped steel (4) is fixedly connected to both ends of the U-shaped structure of the water supply pipe (2). The arc-shaped steel (4) and the U-shaped structure of the water supply pipe (2) are respectively located on both sides of the obstacle (1). The arc-shaped steel (4) and the water supply pipe (2) are located on the same horizontal plane, and the arc-shaped steel (4) and the U-shaped pipeline are coaxially symmetrical. After the arc steel (4) is added, the force exerted by the arc steel (4) on the pipeline is decomposed into a force F1 along the pipeline axis and a force F2 in the radial direction. The U-shaped pipeline is bilaterally symmetrical, and the force exerted by the arc steel (4) perpendicular to the pipeline axis is offset by the elastic reaction force of the soil. The arc-shaped steel (4) is provided with a passivation film on the outside; the arc-shaped steel (4) is any one of an I-shaped steel, a channel steel, a U-shaped steel, and an H-shaped steel.

2. The device for protecting a U-bend pipe according to claim 1, characterized in that: The water return pipe (3) is located between the water supply pipe (2) and the obstacle (1); the two ends of the U-shaped structure of the water return pipe (3) and the water supply pipe (2) are connected respectively via a pipe clamp (5) and a fixing steel (6); and the two ends of the arc-shaped steel (4) are fixedly connected to the two ends of the U-shaped structure of the water return pipe (3).

3. The device for protecting a U-bend pipe according to claim 2, characterized in that: The pipe clamp (5) and the fixing steel (6) are provided with a passivation film on the outside.

4. The device for protecting a U-bend pipe according to claim 2, characterized in that: The two ends of the U-shaped structure of the water return pipe (3) and the water supply pipe (2) are respectively connected via a plurality of pipe hoops (5) and fixing steel (6).

5. The device for protecting a U-bend pipe according to claim 1, characterized in that: The arc-shaped steel (4) is welded to both ends of the U-shaped structure of the water supply pipe (2).

6. The device for protecting a U-bend pipe according to claim 1, characterized in that: A plurality of arc-shaped steels (4) are provided.

7. A protection method for a device for protecting a U-bend pipe as claimed in any one of claims 1 to 6, wherein the U-bend pipe is a U-shaped pipeline formed to bypass an obstacle (1), the pipeline comprising a water supply pipe (2) and a water return pipe (3) laid in parallel, and the plane where the obstacle (1) is located is perpendicular to the water supply pipe (2) and the water return pipe (3); characterized in that: The two ends of an arc steel (4) are welded to the two ends of the U-shaped structure of the water supply pipe (2), or the two ends of the return pipe (3) and the U-shaped structure of the water supply pipe (2) are connected respectively by means of a pipe clamp (5) and a fixing steel (6), and then the two ends of the arc steel (4) are welded to the two ends of the U-shaped structure of the return pipe (3). The arc steel (4) and the U-shaped pipeline are respectively located on both sides of the obstacle (1), the arc steel (4) and the U-shaped pipeline are located on the same horizontal plane, and the arc steel (4) and the U-shaped pipeline are coaxially symmetrical. After the arc steel (4) is added, the force of the arc steel (4) on the pipeline is decomposed into a force F1 along the axial direction of the pipeline and a force F2 in the radial direction. The U-shaped pipeline is bilaterally symmetrical, and the force of the arc steel (4) perpendicular to the axial direction of the pipeline is offset by the elastic reaction force of the soil.

Images