Pipeline laying assembly line in plain area and construction method

Abstract

The invention belongs to the technical field of pipeline construction, and particularly relates to a pipeline lowering assembly line in a plain area and a construction method.The assembly line is arranged at the front end of the starting end of pipe ditch excavation, and the assembly line is sequentially connected with a pipeline frame, a welding platform, a flaw detection platform, a joint coating platform, a pipe ditch support and a tractor in series through a conveying device; a pipeline is stored through the pipeline rack and conveyed to the welding platform for welding connection, welding quality detection is carried out on the flaw detection platform, anti-corrosion treatment is carried out on the joint coating platform, finally, the pipeline enters a pipe ditch through the pipe ditch support and then is connected to the bottom of the excavator through the tractor, and the excavator drags and distributes the pipeline. The problems that the road width is too large and the construction period is too long in traditional pipeline lowering are solved, the construction site can be saved, the construction efficiency is improved, and the construction cost is reduced.

Description

Technical Field

[0001] The present application belongs to the technical field of pipeline construction, and specifically relates to an underground pipeline assembly line and a construction method for a pipeline in a plain area. Background Art

[0002] Construction period is cost, and prolonged construction period leads to a sharp increase in construction cost; site is efficiency, and disorderly site leads to complex equipment movement lines and reduced efficiency. Pipeline construction sites should make full use of road length and reduce width occupancy. In the existing technology, pipeline construction in plain areas still follows the traditional steps of pipe laying, welding processing, trench excavation, and pipeline trenching. Under the construction conditions where urban land resources are extremely tight and the construction period is tight, the traditional pipeline construction method needs to innovate the construction equipment or methods. Summary of the invention

[0003] The present application provides a pipeline laying line in plain areas and a construction method thereof, which can solve the problems of excessive road width occupation and long construction period existing in traditional pipeline laying lines.

[0004] The technical solution of this application is as follows: A pipeline assembly line for a plain area pipeline, the assembly line is arranged at the front end of the trench excavation start end, and a conveying device is arranged from the front end to the trench excavation start end, and the conveying device is connected in series from the front end of the trench excavation to the start end: A pipeline rack, arranged at one side of the conveying device, the pipeline rack is used to store pipeline units and convey the pipeline units to the conveying device; The welding platform is matched with the spacing of the pipeline rack and the length of the pipeline. The welding platform includes a connecting unit and a welding unit. The connecting unit is used to align the ends of two continuous pipelines, weld accessories for the pipelines, and weld the ends of the two continuous pipelines. The accessories include a traction head arranged at the front end of the first section of the pipeline. A flaw detection platform, the spacing between the flaw detection platform and the welding platform matches the length of the pipeline, and the flaw detection platform is used to detect the welding quality of the beginning and end of the pipeline; Patching platform, used to wrap anti-corrosion materials around the ends of the pipeline; The limiting platform comprises a bracket and a locking device, wherein the locking device comprises a sleeve for allowing the pipeline to pass through and a tightening member for clamping the sleeve; A pipe trench support is fixed on the ground and extends obliquely toward the inside of the pipe trench. The bottom of the pipe trench support is provided with pulleys supporting the pipeline at several heights. The tractor comprises hooks at two ends, wherein the two hooks are connected through a turnbuckle and a spring, and the hook at one end of the turnbuckle is connected to the traction head, and the hook at one end of the spring is connected to the bottom of the excavator.

[0005] Furthermore, the conveying device includes a conveying shaft connected to each platform and a plurality of driving wheels arranged on both sides of the conveying shaft to support the pipeline to move on the conveying shaft, and each of the driving wheels is driven by a motor.

[0006] A pipeline laying method in plain areas comprises the following steps: S01) Level the site and arrange the pipelines on the pipeline rack along the direction of the trench; S02) The pipeline rack delivers pipelines to the conveying device; S03) When the first pipeline enters the welding platform, a traction head is welded at the front end of the pipeline, and at the same time, the second pipeline is transported to the conveying device; S04) The first pipeline enters the flaw detection platform for welding quality inspection. At the same time, the front end of the second pipeline is aligned with the rear end of the first pipeline along the central axis and connected by welding through the welding unit; S05) The first pipeline enters the patching platform to be wrapped with anti-corrosion materials. At the same time, the front end of the second pipeline enters the flaw detection platform for welding quality inspection. At the same time, the tail end of the second pipeline is welded and connected to the front end of the third pipeline on the welding platform through a welding unit; S06) loosen the clamping device so that the first pipeline passes through the clamping device and the pipeline support in sequence and then enters the pipeline trench; S07) The excavator enters the trench or straddles both sides of the trench and installs the traction head between the two crawlers; S08) A tractor is installed between the traction head of the first pipeline and the traction head of the excavator. The excavator continuously excavates the trench from the starting end of the trench excavation, and controls the start or stop of the production line according to the excavation distance to match the pipeline connection progress with the excavation distance.

[0007] Further, in step S08), when there is groundwater in the trench, a buoy is installed on the pipeline lowered into the trench; When there is no groundwater in the trench, a detachable pulley block is installed below the pipeline entering the trench.

[0008] Furthermore, the method also includes: S09) when the pipeline reaches the end point, adjusting one end of the turnbuckle screw until the spring returns to its original length and then removing the tractor.

[0009] Further, in step S09), when the pipeline reaches the end point, the height difference between the end point and the starting point is measured. When the height difference exceeds 1.8 m, the soil in front of the middle position of the trench and the back of the middle position of the trench are backfilled, and the tractor is removed.

[0010] Due to the adoption of the above technical solution, the beneficial effects of this application are as follows: 1. The assembly line in this application changes the mode of "connecting first, then laying pipes" in the traditional pipe laying method. In the technical solution of the pipe laying assembly line of this application, the connection and laying of pipes are carried out sequentially, that is, there is no need to connect several pipelines first and then place the pipelines in the trench uniformly. The technical solution of this application can significantly reduce the width of the construction site. Specifically, arranging the pipelines in sequence will occupy the lateral space outside the trench, and the pipelines are generally stacked. Moving the pipelines will complicate the equipment movement line, and the equipment will travel back and forth and be hoisted in the construction site, which will significantly reduce the efficiency. In addition, during the continuous excavation process, it is only necessary to reserve construction space on both sides of the trench, and the movement of the pipelines is carried out inside the trench, that is, this application makes full use of the internal space of the excavated trench, which can significantly reduce the reserved construction space on both sides of the trench excavation. After reducing the construction space, the land requisition area is greatly reduced, thereby reducing the land requisition costs and the costs of later vegetation restoration, while shortening the time for operation cleaning.

[0011] 2. The present application can fully coordinate the progress of pipe laying and trench excavation, and carry out pipe laying simultaneously during the process of pipeline excavation, which not only saves the step of lifting and lowering pipes and reduces construction equipment, but also enables the excavator to play its traction role and reduce the equipment rental cost. In the present application, the welding platform, patching platform, and flaw detection platform are all supported by mature existing technologies, which can significantly improve the connection quality of pipelines and avoid rework. The present application innovatively uses excavation equipment as a traction device, thereby replacing traditional pipe laying. Furthermore, the present application combines the three processes of pipe laying, trench excavation, and pipeline trenching into one, thereby improving construction efficiency, saving construction costs, and reducing construction period.

[0012] 3. The technical solution of the down-pipe assembly line of the present application is provided with a pipeline limiting platform, and the limiting platform is specially designed to cooperate with the tail-end effect generated during the pulling process of the pipeline. In the process of pulling the pipeline, the tail end of the connected pipeline will produce a large displacement. Too large displacement will affect the welding construction of the upstream pipeline and also bring safety hazards to the on-site construction personnel. By designing a limiting platform and controlling the displacement and turning angle of the pipeline in the assembly line, the normal operation of the down-pipe assembly line can be guaranteed. The assembly line works intermittently. When the downstream is higher than the upstream, the limiting device can clamp the pipeline to prevent the pipeline from sliding under the action of gravity, thereby avoiding slippage and impacting the welding process of the upstream pipeline. When the downstream is lower than the upstream, the limiting platform can control the upstream length to ensure the smooth progress of the connection process.

[0013] 4. The tractor in this application is designed to cooperate with the limit device and the construction progress. When the traction process is paused, the pipeline will have an inertial impact, and the spring in the tractor can offset the impact force. In fact, during the pipeline traction process, it is not a strictly straight path. The pipeline is laid elastically, and twisting force will be generated during the traction process. The spring and basket screw in the tractor can reduce the twisting force and release stress by rotating. Moreover, the basket screw can be rotated to adjust the length of the tractor to prevent injury to the construction personnel during removal.

[0014] 5. The construction method of the present application realizes the synchronization of trench excavation and pipe laying. The connection between pipelines and the anti-corrosion of pipelines are carried out in a procedural manner along with the progress of excavation. It can concentrate construction time, synchronize the construction progress of each construction group, reduce construction procedures, and greatly improve the efficiency of excavation and pipe laying. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings described herein are used to provide further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application.

[0016] Figure 1 A schematic diagram of a pipeline downpipe flow line in a plain area provided for this application; Figure 2 This is a schematic diagram of the limiting platform described in this application; Figure 3 A schematic diagram of a trench support in this application; In the attached picture: 1. Conveying device; 1-1. Conveying shaft; 1-2. Driving wheel; 2. Pipe rack; 3. Welding platform; 4. NDT platform; 5. Patching platform; 6. Limiting platform; 6-1. Bracket; 6-2. Hoop; 6-3. Fastener; 7. Trench bracket; 8. Puller; 8-1. Hook; 8-2. Turnbuckle; 8-3. Spring; 9. Puller head. DETAILED DESCRIPTION

[0017] Based on the background technology, traditional pipeline construction is divided into trench construction and trench construction. Trench construction completes most of the processes, while trench construction has fewer steps and mainly involves pipe laying. Traditional pipe laying requires a series of processes such as welding pipelines, anti-corrosion, and welding quality testing at the construction site. The equipment used in these processes requires additional space in the trench. Based on this, this application provides a pipeline laying line in plain areas. As attached Figure 1 ~Attached Figure 3As shown, the assembly line is arranged at the front end of the starting end of the trench excavation, and a conveying device 1 is arranged from the front end to the starting end of the trench excavation. The conveying device 1 includes a conveying shaft 1-1 connecting each platform and a plurality of driving wheels 1-2 arranged on both sides of the conveying shaft 1-1 to support the movement of the pipeline on the conveying shaft 1-1, and each of the driving wheels 1-2 is driven by a motor. The motor drives each driving wheel 1-2 to rotate synchronously, and sequential processing can be achieved by coordinating with the spacing between each platform. The starting end of the trench excavation to the front of the site that does not need to be excavated is the front end of the excavation starting end, and the assembly line of the present application is arranged in the site in front.

[0018] The conveying device 1 is connected in series from the front end of the trench excavation to the starting end: The pipeline rack 2 is arranged at one side of the conveying device 1, and is used to store pipeline units and convey pipeline units to the conveying device 1. The pipeline rack 2 is used to stack the required pipelines, and when the pipelines are light, they can be conveyed to the conveying device 1 manually. As an example but not a limitation, a conveyor belt can also be installed on the pipeline rack 2 to convey it into the conveying device 1.

[0019] The welding platform 3 is matched with the spacing of the pipeline rack 2 and the length of the pipeline. The welding platform 3 includes a connection unit and a welding unit. The connection unit is used to align the ends of two continuous pipelines, and is used to weld accessories for the pipelines and weld the ends of the two continuous pipelines. The accessories include a traction head 9 arranged at the front end of the first section of the pipeline. The traction head 9 is a component connected to the traction device 8. As an example, it can be a ring, and the hook 8-1 forms a reliable connection after hooking with the ring. Before welding, it is necessary to try to align the center line of the pipeline with the connection unit first, and then weld. The connection unit is a prior art, and it can use a pipe external adapter. The conveying device 1 needs to be leveled during installation, so the height of the pipeline in the conveying device 1 is basically the same. The connection unit can be fine-tuned with the adapter to align the ends of the two pipelines. The welding unit uses automatic welding equipment. In specific operations, the selection of automatic welding machine and welding materials is selected according to the aperture wall thickness of the pipe and the material of the pipeline. For example, 20# steel can use E4303 welding wire or gas shielded flux cored wire: such as LQ122, LQ172, LQ212, etc., and automatic welding machines can be selected from Panasonic, Lincoln, Megmeet, ESAB, JASIC, etc.). The automatic welding machine is set in a fixed position to automatically complete the entire welding process, including welding parameter adjustment, welding gun movement, etc.

[0020] The flaw detection platform 4 is spaced apart from the welding platform 3 to match the length of the pipeline, and the flaw detection platform 4 is used to detect the welding quality at the beginning and end of the pipeline. As an example and not a limitation, this application uses conventional ultrasonic testing, which is faster and more efficient. When the flaw detection platform 4 finds that there is a problem with the welding quality, rework is required, and the conveying device 1 flips over and drags the pipeline back to the welding unit for rework. It is also possible to separately install an automatic welding machine behind the flaw detection platform 4 or perform secondary welding manually.

[0021] The patching platform 5 is used to wrap the anticorrosion material around the head and tail of the pipeline. The patching platform 5 can be replaced by a general wrapping machine. In pipeline construction, the method of wrapping a heat shrink sleeve or cold wrapping an anticorrosion tape is usually adopted.

[0022] The limiting platform 6 includes a bracket 6-1 and a locking device, wherein the locking device has a ferrule 6-2 that allows the pipeline to pass through and a tightening member 6-3 that clamps the ferrule 6-2. Figure 2 As shown, the ferrule 6-2 is C-shaped, and pressure is applied to the ferrule 6-2 by the tightening member 6-3 to reduce its opening, thereby achieving fixation.

[0023] The pipe trench support 76-1 is fixed to the ground and extends obliquely into the pipe trench. The bottom of the pipe trench support 76-1 is provided with pulleys at several heights to support the pipeline. Figure 3 As shown, the wheel group in the figure is the pulley. It should be noted that the pipeline has an elastic modulus and can form a certain bend, which does not destroy its function. Therefore, during the pipe laying process, the pipeline needs to be tilted into the trench from the site, and because the depth of the trench is generally shallow, about 1m~1.3m, the curvature of the pipeline can fully allow this pipe laying method. During specific operations, the buried depth of the pipeline should be determined according to the geographical location. For example, in northern my country, it needs to be buried below the frozen soil. The trench bracket 76-1 is anchored to the ground and anchored twice on the side wall of the foundation pit. Pulleys of different heights can take over the pipeline at different positions to ensure that it slides smoothly into the trench.

[0024] The tractor 8 includes hooks 8-1 at both ends, and the two hooks 8-1 are connected through a basket screw 8-2 and a spring 8-3. The hook 8-1 at one end of the basket screw 8-2 is connected to the traction head 9, and the hook 8-1 at one end of the spring 8-3 is connected to the bottom of the excavator.

[0025] In specific implementation, a hooking member for hooking with the hook 8 - 1 needs to be installed between the two crawlers of the excavator. As an example, it can be a circular ring.

[0026] The assembly line in this application changes the mode of "connecting first, then laying pipes" in the traditional pipe laying method. In the technical solution of the pipe laying assembly line of this application, the connection and laying of pipes are carried out sequentially, that is, there is no need to connect several pipelines first and then place the pipelines in the trench uniformly. The technical solution of this application can significantly reduce the width of the construction site. Specifically, arranging the pipelines in sequence will occupy the lateral space outside the trench, and the pipelines are generally stacked. Moving the pipelines will complicate the equipment movement line, and the equipment will travel back and forth and be hoisted in the construction site, which will significantly reduce the efficiency. In addition, during the continuous excavation process, it is only necessary to reserve construction space on both sides of the trench, and the movement of the pipelines is carried out inside the trench, that is, this application makes full use of the internal space of the excavated trench, which can significantly reduce the reserved construction space on both sides of the trench excavation. After reducing the construction space, the land requisition area is greatly reduced, thereby reducing the land requisition costs and the costs of later vegetation restoration, while shortening the time for operation cleaning.

[0027] This application can fully coordinate the progress of pipe laying and trench excavation, and lay pipes during pipeline excavation, which not only saves the steps of lifting and laying pipes, reduces construction equipment, but also enables the excavator to play its traction role and reduce equipment rental costs. In this application, the welding platform 3, the patching platform 5, and the flaw detection platform 4 are all supported by mature existing technologies, which can significantly improve the connection quality of the pipeline and avoid rework.

[0028] When the above-mentioned assembly line is used, the pipeline laying construction specifically includes the following steps: S01) Level the site and arrange the pipelines on the pipeline rack along the direction of the trench; S02) The pipeline rack delivers pipelines to the conveying device; S03) When the first pipeline enters the welding platform, a traction head is welded at the front end of the pipeline, and at the same time, the second pipeline is transported to the conveying device; S04) The first pipeline enters the flaw detection platform for welding quality inspection. At the same time, the front end of the second pipeline is aligned with the rear end of the first pipeline along the central axis and connected by welding through the welding unit; S05) The first pipeline enters the patching platform to be wrapped with anti-corrosion materials. At the same time, the front end of the second pipeline enters the flaw detection platform for welding quality inspection. At the same time, the tail end of the second pipeline is welded and connected to the front end of the third pipeline on the welding platform through a welding unit; S06) loosen the clamping device so that the first pipeline passes through the clamping device and the pipeline support in sequence and then enters the pipeline trench; S07) The excavator enters the trench or straddles both sides of the trench and installs the traction head between the two crawlers; S08) A tractor is installed between the traction head of the first pipeline and the traction head of the excavator. The excavator continuously excavates the trench from the starting end of the trench excavation, and controls the start or stop of the production line according to the excavation distance to match the pipeline connection progress with the excavation distance.

[0029] In step S08), when there is groundwater in the trench, a buoy is installed on the pipeline entering the trench; When there is no groundwater in the trench, a detachable wheel set is installed below the pipeline entering the trench.

[0030] S09) When the pipeline reaches the end point, adjust one end of the basket screw until the spring returns to its original length and then remove the retractor.

[0031] In step S09), when the pipeline reaches the end point, the height difference between the end point and the starting point is measured. When the height difference exceeds 1.8 m, the soil in front of the middle position of the trench and the back of the middle position of the trench are backfilled, and the tractor is removed.

[0032] The technical solution for the down-pipe assembly line applied for has a pipeline limiting platform, which is specially designed to cooperate with the tail-end effect generated during the pulling process of the pipeline. In the process of pulling the pipeline, the tail end of the connected pipeline will produce a large displacement. Excessive displacement will affect the welding construction of the upstream pipeline and also bring safety hazards to on-site construction personnel. By designing a limiting platform and controlling the displacement and turning angle of the pipeline in the assembly line, the normal operation of the down-pipe assembly line can be guaranteed. The assembly line works intermittently. When the downstream is higher than the upstream, the limiting device can clamp the pipeline to prevent the pipeline from sliding under the action of gravity, thereby avoiding slippage and impacting the welding process of the upstream pipeline. When the downstream is lower than the upstream, the limiting platform can control the upstream length to ensure the smooth progress of the connection process.

[0033] The tractor in this application is designed to cooperate with the limit device and the construction progress. When the traction process is paused, the pipeline will have an inertial impact, and the spring in the tractor can offset the impact force. In fact, during the pipeline traction process, it is not a strictly straight path. The pipeline is laid elastically, and twisting force will be generated during the traction process. The spring and basket screw in the tractor can reduce the twisting force and release stress by rotating. Moreover, the basket screw can be rotated to adjust the length of the tractor to prevent damage to the construction personnel during removal.

[0034] The construction method of the present application realizes the synchronization of trench excavation and pipe laying. The connection between pipelines and the corrosion protection of pipelines are carried out in a procedural manner along with the excavation progress. It is possible to concentrate construction time, synchronize the construction progress of each construction group, reduce construction procedures, and greatly increase the efficiency of excavation and pipe laying.

[0035] Taking the pipeline No. 20 Φ219×7 seamless steel pipe, the project volume is 1KM buried pipeline as an example, the effect of improving the construction time of this application is explained in detail. It is assumed that the assembly line of this application and the traditional pipe laying have the same external constraints, only one electric welding equipment, the same machinery and construction equipment, the same construction team, the same geological conditions, and the same project volume.

[0036] Traditional methods generally use mobile cranes on construction sites. Each time a mobile crane is used to lift and lay pipes, it needs to support the legs. The crane moves along the direction of the pipeline. Once it is in place, it is then lifted with the legs. Normally, two pipelines can be lifted at a time. After lifting, the legs are folded and the crane moves forward, and the process is repeated. About 6 to 7 pipes can be laid per hour. Each pipeline is about 10 meters long, and there are about 100 pipelines for 1 km. Pipe laying takes 2 working days.

[0037] The method of the present application eliminates the pipe laying step. When the pipe laying assembly line of the present application is used, it takes 2 hours to lay out the assembly line, check the equipment, and power on. After the pipeline is in place, the trench can be excavated.

[0038] Furthermore, the assembly time of a weld is about 25 minutes to 30 minutes. A 1KM pipeline has about 100 welds, and the assembly takes about 50 hours, about 6 days. During the equipment installation process, the present application controls the pulleys of the conveying device to be at the same height, and the center of the pipeline can be overlapped only by manual fine-tuning. When the present application is implemented, automatic welding equipment is preferably used for welding, and the welding equipment does not need to be moved. When it is installed in a fixed position, it can greatly improve welding efficiency and reduce construction period.

[0039] The welding work is the same for both. The traditional welding method takes about 12 days, which can be reduced by 4 days when the fixed-position automatic welding machine of the present application is used. However, the production line of the present application can also perform weld inspection and anti-corrosion while welding. After the traditional method of anti-corrosion patching is completed, the trench is dug and the trench is excavated using an excavator. Due to the construction surface and safety considerations, the excavation task cannot be carried out at the same time as welding anti-corrosion. It needs to be staggered. It takes 4 days to excavate 1KM. Minus the 2 days of cross time that can be advanced, the construction period needs to be increased by 2 days. It takes 2 days to dig the trench and backfill. This step takes a total of 4 days.

[0040] This application uses an assembly line to weld, inspect welds, and perform corrosion protection at the same time. It also digs the trench and uses the conduit support to dig the trench. The construction period is almost not increased. After the corrosion protection and patching, the pipeline trench is immediately laid. It takes 2 days to dig the trench and backfill. It can save 2 days of trench digging, trenching, and backfilling.

[0041] In general, the traditional method takes 26 days to complete the project, while the present application can complete the project in about 12 days or less, saving 54% of the time overall and reducing construction costs by 20%.

[0042] In specific implementation, there are three modes of pipeline trenching, which can basically solve various situations in plain areas.

[0043] The first is when the trench width is narrow, which is smaller than the width between the two crawlers of the crawler excavator. The excavator can move above the trench. The trench can be excavated in advance or excavated as the pipeline is processed. The excavator installs a bracket and a tractor, digs the trench while pulling the pipeline into the trench, and the travel distance is controlled by GPS, and the excavator moves under the premise of ensuring safety. The excavator is working above the trench, and a pulley block is installed under each pipeline pulled. This method is suitable for pipelines with smaller diameters.

[0044] The second type is when the trench is wide and the groundwater is deep. The groundwater level is deep and there is no water at the bottom of the trench. The excavation equipment can be directly constructed in the excavated trench. The pipeline bracket is fixed at the bottom of the trench to facilitate the pulling of the pipeline and prevent the pipeline from being worn during the dragging process. The subsequent steps are the same as the first type.

[0045] The third type is when the trench is wide and the groundwater is shallow. For areas in the south with dense water networks and high groundwater levels, especially in summer when there are more rainstorms, trench excavation is accompanied by a large amount of open water and the trench is full of water. An excavator with a self-floating function can be used, and a bracket and a tractor can be installed at the bottom of the excavator. While digging the trench, the pipeline is pulled into the trench. The pipeline floats on the water. If the buoyancy is not enough, a buoy can be installed on the pipeline to use the buoyancy of the water to better pull the pipeline. When this method is used, the obstacles to construction caused by too much water are overcome, and water is converted into a booster for construction. If there is less water in the trench, water can be poured to raise the water level, which is conducive to pulling the pipeline. After the pipeline is in place, the buoy is removed, water is added for pressure testing, and it sinks to the bottom of the trench, and a counterweight is added to prevent it from floating up.

[0046] Anything not described in this application can be achieved by adopting or drawing on existing technologies. The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A pipeline under-pipeline production line in plain areas, characterized in that: The assembly line is arranged at the front end of the trench excavation start end, and a conveying device is arranged from the front end to the trench excavation start end, and the conveying device is sequentially connected in series from the front end of the trench excavation to the start end: A pipeline rack, arranged at one side of the conveying device, the pipeline rack is used to store pipeline units and convey the pipeline units to the conveying device; The welding platform is matched with the spacing of the pipeline rack and the length of the pipeline. The welding platform includes a connecting unit and a welding unit. The connecting unit is used to align the ends of two continuous pipelines, weld accessories for the pipelines, and weld the ends of the two continuous pipelines. The accessories include a traction head arranged at the front end of the first section of the pipeline. A flaw detection platform, the spacing between the flaw detection platform and the welding platform matches the length of the pipeline, and the flaw detection platform is used to detect the welding quality of the beginning and end of the pipeline; Patching platform, used to wrap anti-corrosion materials around the ends of the pipeline; The limiting platform comprises a bracket and a locking device, wherein the locking device comprises a sleeve for allowing the pipeline to pass through and a tightening member for clamping the sleeve; A pipe trench support is fixed on the ground and extends obliquely toward the inside of the pipe trench. The bottom of the pipe trench support is provided with pulleys supporting the pipeline at several heights. The tractor comprises hooks at two ends, wherein the two hooks are connected through a turnbuckle and a spring, and the hook at one end of the turnbuckle is connected to the traction head, and the hook at one end of the spring is connected to the bottom of the excavator.

2. The pipeline under-line assembly line in plain areas according to claim 1 is characterized in that: The conveying device comprises a conveying shaft connected to each platform and a plurality of driving wheels arranged on both sides of the conveying shaft to support the pipeline to move on the conveying shaft, and each of the driving wheels is driven by a motor.

3. A method for laying pipelines in plain areas using the assembly line of claim 1, characterized in that: The following steps are involved: S01) Level the site and arrange the pipelines on the pipeline rack along the direction of the trench; S02) The pipeline rack delivers pipelines to the conveying device; S03) When the first pipeline enters the welding platform, a traction head is welded at the front end of the pipeline, and at the same time, the second pipeline is transported to the conveying device; S04) The first pipeline enters the flaw detection platform for welding quality inspection. At the same time, the front end of the second pipeline is aligned with the rear end of the first pipeline along the central axis and connected by welding through the welding unit; S05) The first pipeline enters the patching platform to be wrapped with anti-corrosion materials. At the same time, the front end of the second pipeline enters the flaw detection platform for welding quality inspection. At the same time, the tail end of the second pipeline is welded and connected to the front end of the third pipeline on the welding platform through a welding unit; S06) loosen the clamping device so that the first pipeline passes through the clamping device and the pipeline support in sequence and then enters the pipeline trench; S07) The excavator enters the trench or straddles both sides of the trench and installs the traction head between the two crawlers; S08) A tractor is installed between the traction head of the first pipeline and the traction head of the excavator. The excavator continuously excavates the trench from the starting end of the trench excavation, and controls the start or stop of the production line according to the excavation distance to match the pipeline connection progress with the excavation distance.

4. The method for laying pipelines in plain areas according to claim 3 is characterized in that: In step S08), when there is groundwater in the trench, a buoy is installed on the pipeline entering the trench; When there is no groundwater in the trench, a detachable pulley block is installed below the pipeline entering the trench.

5. The method for laying pipelines in plain areas according to claim 3 is characterized in that: The method further comprises: S09) When the pipeline reaches the end point, adjust one end of the basket screw until the spring returns to its original length and then remove the retractor.

6. The method for laying pipelines in plain areas according to claim 5 is characterized in that: In step S09), when the pipeline reaches the end point, the height difference between the end point and the starting point is measured. When the height difference exceeds 1.8m, the soil in front of the middle position of the trench and the back of the middle position of the trench are backfilled, and the tractor is removed.

Images