Device for welding pipeline and pipeline welding method

Abstract

The invention relates to the technical field of pipeline welding construction, in particular to a device for welding a pipeline and a pipeline welding method. The device for welding the pipeline comprises a guide rail, the guide rail sleeves the pipeline in a surrounding mode, the axis of the guide rail is parallel to the axis of the pipeline, and the surrounding size of the guide rail is adjustable; the multiple supporting components are arranged on the inner side of the guide rail, the multiple supporting components are arranged in the length direction of the guide rail at intervals, the supporting components abut against the outer wall of the pipeline in the radial direction of the pipeline, and the length of the supporting components is adjustable; the walking device is connected to the outer side of the guide rail and can move in the length direction of the guide rail; and the welding machine is connected to the side, back on to the guide rail, of the walking device, and the welding machine is used for welding two pipelines with opposite ends. According to the pipeline welding device, the defects that in the prior art, when two pipelines with opposite ends are welded, a circle of guide rail is mostly arranged outside the pipelines in a sleeving mode, however, the open-air pipelines can expand with heat and contract with cold, and the pipelines with the fixed size cannot be correspondingly adjusted are overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of pipeline welding construction, and particularly relates to a device for welding pipelines and a method for pipeline welding. Background Art

[0002] In water conservancy projects, pipeline welding is a core technical link to ensure the sealing performance, structural strength and corrosion resistance of the water conveyance system. The welding quality is directly related to the leakage risk and service life of the pipe network. Especially in high-pressure water conveyance, underground culverts or inter-basin water diversion projects, the integrity of the weld can resist the stress concentration caused by water hammer impact, sediment erosion and foundation settlement. In the prior art, for the circumferential welding of large-diameter pipelines, an automated process of setting a circular closed guide rail on the outer wall of the pipeline is generally adopted: the welding path is accurately positioned through a magnetic adsorption type track, and a linkage welding trolley is carried to weld two adjacent pipelines.

[0003] However, in some projects, the pipelines set outdoors will undergo thermal expansion and contraction, and the existing guide rails cannot adjust the enclosed size, which affects the welding accuracy. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiency in the prior art that when welding two pipelines with opposite welding ends, a circular guide rail is mostly sleeved outside the pipeline, but the pipelines set outdoors will undergo thermal expansion and contraction, and the pipelines with fixed sizes cannot be adjusted correspondingly, and to provide a device for welding pipelines and a method for pipeline welding.

[0005] In a first aspect, the present invention provides a device for welding pipelines, comprising: A guide rail, the guide rail is sleeved outside the pipeline in a surrounding manner, the axis of the guide rail is parallel to the axis of the pipeline, and the enclosed size of the guide rail is adjustable; A plurality of support members, a plurality of the support members are all arranged inside the guide rail, the plurality of support members are arranged at intervals along the length direction of the guide rail, the support members abut against the outer wall of the pipeline in the radial direction of the pipeline, and the length of the support members is adjustable; A traveling device, the traveling device is connected to the outside of the guide rail, and the traveling device can move along the length direction of the guide rail; A welding machine, the welding machine is connected to the side of the traveling device facing away from the guide rail, and the welding machine is used for welding two pipelines with opposite ends.

[0006] The axis of the guide rail is perpendicular to the plane where the circular guide rail is located and passes through the center of the circular guide rail. The inner side of the guide rail is the side facing the pipeline, and the outer side of the guide rail is the side facing away from the pipeline.

[0007] If the size of the guide rail enclosure is adjustable, the distance between the guide rail and the pipeline can be adjusted by adjusting the size of the guide rail enclosure. The self-length of the support member is adjusted according to the enclosure size of the guide rail. The support frame abuts against the outer wall of the pipeline along the radial direction of the pipeline, and can bear the weight of the welding machine as much as possible, which is beneficial to improving the stability of the structure, thereby being able to improve the welding accuracy as much as possible. If the size of the guide rail enclosure is adjustable and the self-length of the support member is adjustable, when the pipeline is set outdoors, if the pipeline expands and contracts due to heat, the distance between the guide rail and the pipeline can be adjusted to ensure the welding accuracy and efficiency as much as possible; and it can also be adapted to pipelines of different sizes. Preferably, the support member includes a pressing plate frame and a telescopic rod. One end of the telescopic rod is connected to the pressing plate frame, and the other end is connected to the inner side of the guide rail. The pressing plate frame is connected to the outer wall of the pipeline.

[0008] The telescopic rod is connected to the outer wall of the pipeline through the pressing plate frame, which can avoid stress concentration at the connection as much as possible. The use of a telescopic rod facilitates the adjustment of the self-length of the support member.

[0009] Preferably, the guide rail is provided with a first screw hole, and a first bolt passes through the first screw hole and is connected to the end of the telescopic rod away from the pressing plate frame.

[0010] Fixing the telescopic rod to the inner side of the guide rail through the first screw hole and the first bolt is beneficial to improving the stability of the structure.

[0011] Preferably, the guide rail is provided with a plurality of second screw holes, and the plurality of second screw holes are arranged at intervals along the length direction of the guide rail. The size of the guide rail enclosure is adjusted by overlapping and connecting different second screw holes.

[0012] The size of the guide rail enclosure is adjusted by connecting different second screw holes, so as to adjust the distance between the guide rail and the outer wall of the pipeline. And the guide rail connected and enclosed by this method is convenient for installation and is beneficial to improving the construction efficiency.

[0013] Preferably, the traveling device includes traveling wheels, guide wheels and a guide platform. The guide wheels are arranged on both sides of the traveling device, the traveling wheels are arranged in the middle of the traveling device, the guide platform is arranged relative to the guide wheels, the guide platform abuts against the inner side of the guide rail, the guide wheels abut against the outer side of the guide rail, and the distance between the guide wheels and the guide platform is adjustable.

[0014] If the distance between the guide wheels and the guide platform is adjustable, it can be adapted to guide rails of different thicknesses.

[0015] Preferably, the traveling device includes two sets of traveling wheels, and the two sets of traveling wheels are respectively connected to the inner side and the outer side of the guide rail, and the two sets of traveling wheels are used to clamp the guide rail.

[0016] By setting two sets of opposite walking wheels to clamp the guide rail, when the walking device walks below the axis of the pipeline, it can also ensure that the walking speed of the walking device is not affected as much as possible, and the welding efficiency is ensured as much as possible.

[0017] Preferably, an eccentric sensor, a speed monitoring device and a current monitoring device are arranged at the welding end of the welding machine. The eccentric sensor is used to monitor the relative position between the welding torch of the welding machine and the weld seam. The speed monitor is used to monitor the walking speed of the walking device. The current monitoring device is used to monitor the current of the welding machine.

[0018] The eccentric sensor is used to monitor whether the welding torch is eccentric. The speed monitor is used to monitor the walking speed of the walking device, so as to judge whether the walking speed of the walking device is suitable for the pressure applied by the welding torch to the weld seam. The current monitoring device is used to monitor the current of the welding machine, so as to judge whether the current of the welding machine is suitable for the material of the pipeline and the welding requirements, etc. Preferably, the eccentric sensor, the speed monitoring device and the current monitoring device are all connected to a PLC controller. The PLC controller can control the start-stop and walking speed of the walking device, and the PLC controller can control the orientation of the welding torch.

[0019] The PLC controller can control the start-stop and walking speed of the walking device and the orientation of the welding torch, which is beneficial to improving the welding quality and avoiding rework as much as possible.

[0020] In a second aspect, the present invention provides a method for welding a pipeline, comprising the following steps: S1. Install a device for welding a pipeline as described above outside the pipeline; S2. Conduct a trial weld on the pipeline. During the trial weld, measure the current and voltage of the welding machine and the walking speed of the walking device, and calculate whether the welding heat input meets the requirements of the material and thickness of the pipeline. If it meets the requirements, weld along the circumference of the pipeline. If it does not meet the requirements, adjust at least one parameter of the current and voltage of the welding machine and the walking speed of the walking device, and recalculate the welding heat input until the requirements of the material and thickness of the pipeline are met; S3. After the walking device walks along the guide rail for at least one circle, disconnect the power supply and remove a device for welding a pipeline as described above to complete the welding of the pipeline.

[0021] The welding heat input refers to the heat energy input by the welding energy to the weld per unit length during fusion welding, which is calculated from the current and voltage of the welding machine and the walking speed of the walking device. By using a device for welding a pipeline as described above, the size enclosed by the guide rail can be adjusted according to the environment where the pipeline is located, and it is adapted to the pipeline set outdoors.

[0022] Preferably, between step S2 and step S3, ultrasonic flaw detection of the weld seam is also included.

[0023] Performing ultrasonic flaw detection on the weld seam can ensure the welding quality as much as possible.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention provides a device for welding pipes, which includes a guide rail. The size enclosed by the guide rail is adjustable. The guide rail is connected to the outer wall of the pipe through a number of support members, and the length of the support members themselves is adjustable. A traveling device is provided on the guide rail, and the traveling device can move along the length direction of the guide rail. A welding machine is also provided on the traveling device. Since the size enclosed by the guide rail is adjustable, the distance from the guide rail to the pipe can be adjusted by adjusting the size enclosed by the guide rail. The length of the support members themselves is adjusted according to the size enclosed by the guide rail. The support frame abuts against the outer wall of the pipe in the radial direction of the pipe, which can bear the weight of the welding machine as much as possible, is beneficial to improving the stability of the structure, and thus can improve the welding accuracy as much as possible. Since the size enclosed by the guide rail is adjustable and the length of the support members themselves is adjustable, when the pipe is installed outdoors, if the pipe undergoes thermal expansion and contraction, the distance from the guide rail to the pipe can be adjusted to ensure the welding accuracy and efficiency as much as possible; and it can also be adapted to pipes of different sizes. This application overcomes the deficiency in the prior art that when welding two pipes with opposite welding ends, a ring-shaped guide rail is mostly sleeved outside the pipe, but the outdoor pipe will have thermal expansion and contraction changes, and the pipe with a fixed size cannot be adjusted correspondingly.

[0025] 2. The present invention provides a method for welding pipes. First, install the above-mentioned device for welding pipes, then perform a trial weld. If the requirements are met, welding is carried out. If the requirements are not met, at least one parameter among the current and voltage of the welding machine and the traveling speed of the traveling device is adjusted; after the traveling device travels along the guide rail for at least one circle, the power supply is disconnected and the above-mentioned device for welding pipes is removed to complete the welding of the pipe. By using the above-mentioned device for welding pipes, the size enclosed by the guide rail can be adjusted according to the environment where the pipe is located, and it is adapted to pipes installed outdoors. Brief Description of the Drawings

[0026] Figure 1 is a front view schematic diagram of a device for welding pipes according to the present invention; Figure 2 is Figure 1 an enlarged view of part A in Figure 3 is a side view schematic diagram of a device for welding pipes according to the present invention; Figure 4 is Figure 3 an enlarged view of part B in Figure 5 It is a top view schematic diagram of a device for welding pipelines according to the present invention; Icon: 1 - pressure plate frame, 2 - telescopic rod, 3 - guide rail, 4 - first bolt, 5 - traveling device, 6 - welding torch, 7 - guiding platform, 8 - second bolt, 9 - pipeline, 10 - traveling wheel, 11 - guiding wheel, 12 - connecting rod, 13 - second screw hole. Specific embodiments

[0027] The present invention will be further described in detail below in conjunction with specific embodiments. However, this should not be construed as limiting the scope of the above - mentioned subject matter of the present invention to the following embodiments. All technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0028] In the description of the specific embodiments of the present invention, without special explanation, the expression terms of orientation or positional relationship such as "upper", "lower", "left", "right", "center", "inner", "outer", etc. are all based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the invention product / equipment / device is normally used. These terms of orientation or positional relationship are only for facilitating the description of the present invention scheme or simplifying the description in specific embodiments, facilitating technicians to quickly understand the scheme, rather than indicating or implying that a specific device / component / element must have a specific orientation or be constructed and operated in a specific positional relationship. Therefore, it should not be construed as a limitation to the present invention.

[0029] In addition, for terms such as "horizontal", "vertical", "hanging", "parallel", etc., it does not mean that the corresponding device / component / element is required to be absolutely horizontal or vertical or hanging or parallel, but it can be slightly inclined or have a deviation. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and it does not mean that the structure must be completely horizontal, but it can be slightly inclined. Or, it can be simply understood that the corresponding device / component / element is set in the directions of "horizontal", "vertical", "hanging", "parallel", etc., and can have an error / deviation of ±10% relative to the corresponding direction setting, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, more preferably within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still play its role in the present invention scheme.

[0030] In addition, the expressions such as "first", "second", "third", etc. in the terms are only used to distinguish the description of the same or similar components, and should not be construed as emphasizing or implying the relative importance of specific components.

[0031] In addition, in the description of the embodiments of the present invention, "several", "multiple", and "a number of" represent at least two. It can be any situation such as 2, 3, 4, 5, 6, 7, 8, 9, etc., or even more than 9.

[0032] In addition, in the description of the technical solution of the present invention, unless otherwise clearly specified / defined / restricted, where the terms "set", "installed", "connected", "coupled", "provided with", "laid", "arranged" appear, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection. It can be connection means commonly used in the art such as welding, riveting, bolting, and threaded connection. Such a connection can be a mechanical connection, an electrical connection, or a communication connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components.

[0033] Embodiment 1 As Figures 1 to 5 shown, a device for welding pipelines includes: A guide rail 3, the guide rail 3 is enclosed and sleeved outside the pipeline 9, the axis of the guide rail 3 is parallel to the axis of the pipeline 9, and the enclosed size of the guide rail 3 is adjustable; A number of support members, a number of the support members are all arranged inside the guide rail 3, the number of the support members are arranged at intervals along the length direction of the guide rail 3, the support members are radially abutted against the outer wall of the pipeline 9 along the pipeline 9, and the length of the support members is adjustable; A traveling device 5, the traveling device 5 is connected to the outside of the guide rail 3, and the traveling device 5 can move along the length direction of the guide rail 3; A welding machine, the welding machine is connected to the side of the traveling device 5 facing away from the guide rail 3, and the welding machine is used to weld two pipelines 9 with opposite ends.

[0034] Since the enclosed size of the guide rail 3 is adjustable, the distance between the guide rail 3 and the pipeline 9 can be adjusted by adjusting the enclosed size of the guide rail 3. The length of the support member is adjusted according to the enclosed size of the guide rail 3. The support frame is radially abutted against the outer wall of the pipeline 9 along the pipeline 9, which can bear the weight of the welding machine as much as possible, facilitating the improvement of the stability of the structure, and thus the welding accuracy can be improved as much as possible. Since the enclosed size of the guide rail 3 is adjustable and the length of the support member is adjustable, when the pipeline 9 is set outdoors, if the pipeline 9 undergoes thermal expansion and contraction, the distance between the guide rail 3 and the pipeline 9 can be adjusted to ensure the welding accuracy and efficiency as much as possible; and it can also be adapted to pipelines 9 of different sizes. In this embodiment, the guide rail 3 can be a sheet steel, and its specific size is determined according to the actual situation.

[0035] In an alternative embodiment, the support member includes a pressing plate frame 1 and a telescopic rod 2. One end of the telescopic rod 2 is connected to the pressing plate frame 1, and the other end is connected to the inner side of the guide rail 3. The pressing plate frame 1 is connected to the outer wall of the pipeline 9. The telescopic rod 2 can be a sleeve-type rod or a lead screw-type rod. The specific form of the pressing plate frame 1 is determined according to the specific form of the telescopic rod 2. For example, if the telescopic rod 2 is a lead screw-type rod, the pressing plate frame 1 needs to be provided with a nut. The length of the telescopic rod 2 can be adjusted manually or by hydraulic or electric means.

[0036] The telescopic rod 2 is connected to the outer wall of the pipeline 9 through the pressing plate frame 1, so as to avoid stress concentration at the connection as much as possible. The use of the telescopic rod 2 facilitates adjusting the self-length of the support member.

[0037] In this embodiment, as Figure 1 shown, six support members are evenly spaced along the circumference of the pipeline 9. However, in actual use, the number of support members is not limited, and the even spacing arrangement is not limited either, and it can be set according to actual needs.

[0038] In an alternative embodiment, the guide rail 3 is provided with a first screw hole ( Figures 1 - 5 not shown in both figures), and the first bolt 4 passes through the first screw hole and is connected to the end of the telescopic rod 2 away from the pressing plate frame 1.

[0039] In an alternative embodiment, as Figure 3 and Figure 5 shown, the guide rail 3 is provided with a plurality of second screw holes 13, and the plurality of second screw holes 13 are spaced along the length direction of the guide rail 3. By overlapping and connecting different second screw holes 13, the size of the enclosure formed by the guide rail 3 can be adjusted.

[0040] In an alternative embodiment, as Figures 2 - 4 shown, the traveling device 5 includes traveling wheels 10, guide wheels 11 and a guide platform 7. The guide wheels 11 are arranged on both sides of the traveling device 5, the traveling wheels 10 are arranged in the middle of the traveling device 5, the guide platform 7 is arranged relative to the guide wheels 11, the guide platform 7 abuts against the inner side of the guide rail 3, the guide wheels 11 abut against the outer side of the guide rail 3, and the distance between the guide wheels 11 and the guide platform 7 is adjustable.

[0041] In this embodiment, the guide platform 7 and the guide wheels 11 are connected by a connecting rod 12, and the connecting rod 12 is arranged outside the guide wheels 11. The guide platform 7 can move along the length direction of the connecting rod 12, so as to adjust the distance between the guide wheels 11 and the guide platform 7.

[0042] In an alternative embodiment, the traveling device 5 can also be replaced with: including two sets of the traveling wheels 10 ( Figures 1 - 5 The structural form is not shown in either of them), the two sets of the traveling wheels 10 are respectively connected to the inner side and the outer side of the guide rail 3, and the two sets of the traveling wheels 10 are used to clamp the guide rail 3. By arranging the two sets of opposite traveling wheels 10 to clamp the guide rail 3, when the traveling device 5 travels to the lower part of the axis of the pipeline 9, it can also ensure that the traveling speed of the traveling device 5 is not affected as much as possible, and the welding efficiency can be ensured as much as possible.

[0043] In an alternative embodiment, an eccentric sensor ( Figures 1 - 5 not shown in either of them), a speed monitoring device ( Figures 1 - 5 not shown in either of them), and a current monitoring device ( Figures 1 - 5 not shown in either of them) are arranged at the welding end of the welding machine. The eccentric sensor is used to monitor the relative position between the welding torch 6 of the welding machine and the weld seam. The speed monitor is used to monitor the traveling speed of the traveling device 5. The current monitoring device is used to monitor the current of the welding machine. The eccentric sensor is used to monitor whether the welding torch 6 is eccentric. The speed monitor is used to monitor the traveling speed of the traveling device 5, so as to judge whether the traveling speed of the traveling device 5 is adapted to the pressure exerted by the welding torch 6 on the weld seam. The current monitoring device is used to monitor the current of the welding machine, so as to judge whether the current of the welding machine is adapted to the material of the pipeline 9 and the welding requirements, etc. In the actual use process, the eccentric sensor can adopt a laser alignment detector or a laser vision sensor; the speed monitoring device can adopt an encoder or a laser velocimeter; the current monitoring device can adopt an arc sensor.

[0044] In an alternative embodiment, the eccentric sensor, the speed monitoring device, and the current monitoring device are all connected to a PLC controller. The PLC controller can control the start, stop, and traveling speed of the traveling device 5, and the PLC controller can control the orientation of the welding torch 6.

[0045] Embodiment 2 A method for welding a pipeline includes: S1. Install a device for welding a pipeline as described in Embodiment 1 outside the pipeline 9; S2. Perform a trial weld on the pipeline 9. During the trial weld, measure the current and voltage of the welding machine and the traveling speed of the traveling device 5, and calculate whether the welding heat input meets the requirements of the material and thickness of the pipeline 9. If it meets the requirements, perform welding along the circumference of the pipeline 9. If it does not meet the requirements, adjust at least one parameter of the current and voltage of the welding machine and the traveling speed of the traveling device 5, and recalculate the welding heat input until the requirements of the material and thickness of the pipeline 9 are met; S3. After the traveling device 5 travels along the guide rail 3 for at least one circle, disconnect the power supply, remove the device for welding pipes as described in Embodiment 1, and complete the welding of the pipe 9.

[0046] Between step S2 and step S3, ultrasonic flaw detection of the weld seam is also included.

[0047] The wire feeding speed of the welding machine can be estimated from the current of the welding machine and is obtained by referring to the following formula: Wire feeding speed (m / min) ≈ 10 × wire diameter (mm) × current (A).

[0048] The heat input during welding is obtained by the following formula: Heat input during welding (kJ / cm) = welding speed (cm / min) × 1000 / 60 × voltage (V) × current (A).

[0049] Before step S1, the distance between the guide rail 3 and the pipe 9 needs to be determined. In the actual installation process, the distance between the guide rail 3 and the pipe 9 is determined not only by the ambient temperature but also by considering whether the pipe has anti-seismic requirements, etc.

[0050] The above content is only the preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A device for welding pipes, characterized in that, Comprising: A guide rail (3), the guide rail (3) enclosing and sheathing outside a pipeline (9), the axis of the guide rail (3) being parallel to the axis of the pipeline (9), and the enclosed size of the guide rail (3) being adjustable; A plurality of support members, a plurality of the support members are all arranged inside the guide rail (3), a plurality of the support members are arranged at intervals along the length direction of the guide rail (3), the support members abut against the outer wall of the pipeline (9) in the radial direction of the pipeline (9), and the length of the support members is adjustable; A traveling device (5), the traveling device (5) being connected to the outside of the guide rail (3), and the traveling device (5) being capable of moving along the length direction of the guide rail (3); A welding machine, the welding machine being connected to the side of the traveling device (5) facing away from the guide rail (3), and the welding machine being used for welding two opposite ends of the pipelines (9).

2. The device for welding pipes according to claim 1, characterized in that, The support member comprises a pressing plate frame (1) and a telescopic rod (2), one end of the telescopic rod (2) is connected to the pressing plate frame (1), and the other end is connected to the inside of the guide rail (3), and the pressing plate frame (1) is connected to the outer wall of the pipeline (9).

3. The device for welding pipes according to claim 2, characterized in that, The guide rail (3) is provided with a first screw hole, and a first bolt (4) passes through the first screw hole and is connected to the end of the telescopic rod (2) away from the pressing plate frame (1).

4. A device for welding pipes according to any one of claims 1-3, characterized in that, The guide rail (3) is provided with a plurality of second screw holes (13), a plurality of the second screw holes (13) are arranged at intervals along the length direction of the guide rail (3), and the enclosed size of the guide rail (3) is adjusted by overlapping and connecting different second screw holes (13).

5. A device for welding pipes according to any one of claims 1 - 3, characterized in that, The traveling device (5) comprises traveling wheels (10), guide wheels (11) and a guide platform (7), the guide wheels (11) are arranged on both sides of the traveling device (5), the traveling wheels (10) are arranged in the middle of the traveling device (5), the guide platform (7) is arranged relative to the guide wheels (11), the guide platform (7) abuts against the inside of the guide rail (3), the guide wheels (11) abut against the outside of the guide rail (3), and the distance between the guide wheels (11) and the guide platform (7) is adjustable.

6. A device for welding pipes according to any one of claims 1-3, characterized in that, The traveling device (5) comprises two groups of the traveling wheels (10), the two groups of the traveling wheels (10) are respectively connected to the inside and the outside of the guide rail (3), and the two groups of the traveling wheels (10) are used for clamping the guide rail (3).

7. A device for welding pipes according to any one of claims 1-3, characterized in that, The welding end of the welding machine is provided with an eccentric sensor, a speed monitoring device and a current monitoring device, the eccentric sensor is used for monitoring the relative position between the welding torch (6) of the welding machine and the weld seam, the speed monitor is used for monitoring the traveling speed of the traveling device (5), and the current monitoring device is used for monitoring the current of the welding machine.

8. A device for welding pipes according to claim 7, characterized in that, The eccentric sensor, the speed monitoring device and the current monitoring device are all connected to a PLC controller, the PLC controller can control the start-stop and traveling speed of the traveling device (5), and the PLC controller can control the orientation of the welding torch (6).

9. A method for pipeline welding, characterized in that, Comprising the following steps: S1. Install a device for welding pipelines as described in any one of claims 1-8 outside the pipeline (9); S2. Conduct a trial weld on the pipeline (9). During the trial weld, measure the current and voltage of the welding machine and the traveling speed of the traveling device (5), and calculate whether the welding heat input meets the requirements of the material and thickness of the pipeline (9). If it meets the requirements, perform welding along the circumferential direction of the pipeline (9); if it does not meet the requirements, adjust at least one parameter among the current and voltage of the welding machine and the traveling speed of the traveling device (5), and recalculate the welding heat input until the requirements of the material and thickness of the pipeline (9) are met. S3. After the traveling device (5) travels along the guide rail (3) for at least one circle, disconnect the power supply and remove the device for welding pipelines according to any one of claims 1-8 to complete the welding of the pipeline (9).

10. A method for pipeline welding according to claim 9, characterized in that, Between step S2 and step S3, ultrasonic flaw detection of the weld seam is also included.

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