Long-distance oil and gas pipeline demagnetization and heating integrated machine

Abstract

The present invention discloses an integrated demagnetization and heating machine for long-distance oil and gas pipelines, comprising a medium-frequency heating cable / AC demagnetization cable and a DC demagnetization cable respectively wound on the inner and outer sides of the outer surfaces of the upstream and downstream pipelines to be welded, and the input ends of the two sets of the medium-frequency heating cables / AC demagnetization cables and DC demagnetization cables are each electrically connected to a set of pipeline demagnetization and heating integrated machines that integrate the pipeline demagnetization function and the pipeline heating function. The application of the present invention can not only reduce the power consumption of the equipment and the space occupied by the working pit, but also simplify the on-site demagnetization and heating steps of the pipeline to be welded, reduce construction time, and improve work efficiency. More importantly, the present invention fundamentally eliminates the possibility of the pipeline on the side to be welded being simultaneously demagnetized by AC and heated by medium frequency, thereby improving the safety of the pipeline welding construction process.

Description

Technical Field

[0001] The invention relates to the technical field of pipeline welding demagnetization and heating, in particular to an integrated demagnetization and heating machine for long-distance oil and gas pipelines. Background Art

[0002] Before welding large-diameter, long-distance oil and gas pipelines in the field, it is necessary to eliminate the magnetism of the steel pipes to prevent arc blow during welding. At the same time, in order to ensure the welding quality, the welding area needs to be preheated to the specified temperature according to the welding process requirements. After welding is completed, the pipes at the welding point still need to be slowly cooled down.

[0003] In this process, two special equipments are needed: pipeline demagnetization equipment and pipeline medium frequency heating equipment. Currently, there are many related discrete equipments in use on the market.

[0004] For large-diameter pipeline welding, a degaussing machine is required on each side of each weld. Furthermore, a medium-frequency heating device is also required on each side of the weld during the welding process. Since large-diameter pipeline assembly and welding construction typically takes place outdoors, especially during repairs of in-service pipelines, which are typically buried approximately 3 to 5 meters underground, a pit must be excavated before welding. While this is relatively easy in plain areas, excavating a pit in mountainous areas, especially during summer, presents significant challenges. This results in long construction times, multiple degaussing and heating steps, and low efficiency. In light of these challenges, a comprehensive degaussing and heating device for long-distance oil and gas pipelines has been proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a long-distance oil and gas pipeline demagnetization and heating integrated machine to solve the problems raised in the above background technology.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: a long-distance oil and gas pipeline demagnetization and heating integrated machine, comprising a demagnetization and heating integrated machine and an upstream pipeline and a downstream pipeline waiting to be welded, wherein the inner and outer sides of the outer surfaces of the upstream pipeline and the downstream pipeline are respectively wound with a medium frequency heating cable / AC demagnetization cable and a DC demagnetization cable, and the input ends of the two sets of the medium frequency heating cables / AC demagnetization cables and DC demagnetization cables are each electrically connected to a set of pipeline demagnetization and heating integrated machine that integrates the pipeline demagnetization function and the pipeline heating function.

[0007] Preferably, the pipeline demagnetization and heating integrated machine includes a pipeline medium frequency heating unit, a programmable switching unit, a pipeline AC demagnetization unit, a first programmable switch unit, a pipeline DC demagnetization unit and a programmable logic controller; the transmission and reception of electrical signals and control signals of the pipeline medium frequency heating unit, the programmable switching unit, the pipeline AC demagnetization unit, the first programmable switch unit and the pipeline DC demagnetization unit are all controlled by the programmable logic controller.

[0008] Preferably, outer surfaces of the upstream pipeline and the downstream pipeline in the interface direction are both equipped with a magnetic field intensity sensor and a temperature sensor, and the magnetic field intensity sensor and the temperature sensor are electrically connected to the programmable logic controller respectively.

[0009] Preferably, the number of temperature sensors used is 8.

[0010] A method for using a solution based on a demagnetization and heating integrated machine for long-distance oil and gas pipelines includes the following steps:

[0011] Step a: When the start button is pressed, the programmable logic controller automatically collects the magnetic field intensity data and temperature data at the pipeline weld and performs relevant logical operations;

[0012] Step b: under the control of the programmable logic controller, the first program-controlled switch unit is disconnected, and the program-controlled switching unit is switched to the AC degaussing unit;

[0013] Step c: The programmable logic controller starts automatic AC demagnetization according to the collected magnetic field strength data until the magnetic field strength of the pipeline at the weld joint is reduced to a specified range, stops the AC demagnetization work, and gives an audible and visual prompt once;

[0014] Step d: the programmable logic controller controls the program-controlled switching unit to disconnect from the AC degaussing unit, and then controls the first program-controlled switch unit to close;

[0015] Step e: The PLC controls the DC degaussing unit to perform DC degaussing. The PLC automatically adjusts the DC output current until the magnetic field strength at the weld joint falls within the specified range, and then issues an audible and visual warning. The PLC continues to automatically adjust and control the DC degaussing unit to maintain the magnetic field strength at the weld joint within the specified range.

[0016] Step f: The programmable logic controller controls the program-controlled switching unit to switch the medium frequency heating cable / AC degaussing cable to the pipeline medium frequency heating unit, and heats the pipeline at the weld according to the built-in or preset temperature rise curve until the temperature reaches the specified requirement. An audible and visual prompt is given once for a long time to remind the operator that the pipeline welding operation can be carried out; at the same time, the programmable logic controller continues to automatically adjust and control the pipeline medium frequency heating unit to maintain the temperature value at the pipeline weld within the specified range;

[0017] Step g: After the pipeline welding is completed, according to the operator's instructions, the programmable logic controller disconnects the first program-controlled switch unit and automatically adjusts and controls the pipeline medium-frequency heating unit to perform insulation and cooling work on the pipeline at the weld according to the built-in or preset insulation and cooling curves;

[0018] Step h: After the heat preservation and cooling work is completed, the programmable logic controller disconnects the program-controlled switching unit, performs an audible and visual prompt, and then switches the device to standby mode.

[0019] Another solution for a long-distance oil and gas pipeline demagnetization and heating integrated machine, the long-distance oil and gas pipeline demagnetization and heating integrated machine, includes a demagnetization and heating integrated machine and an upstream pipeline and a downstream pipeline waiting to be welded, the outer surface of the upstream pipeline is wrapped with a medium frequency heating cable, the outer surface of the downstream pipeline is wrapped with a medium frequency heating cable / AC demagnetization cable and a DC demagnetization cable, the input ends of the medium frequency heating cable / AC demagnetization cable, the DC demagnetization cable and the medium frequency heating cable are electrically connected to the pipeline demagnetization and heating integrated machine that integrates the pipeline demagnetization function and the pipeline heating function.

[0020] Preferably, the pipeline demagnetization and heating integrated machine includes a pipeline medium frequency heating unit, a programmable switching unit, a pipeline AC demagnetization unit, a first programmable switch unit, a pipeline DC demagnetization unit, a programmable logic controller and a second programmable switch unit; the transmission and reception of electrical signals and the transmission and reception of control signals of the pipeline medium frequency heating unit, the programmable switching unit, the pipeline AC demagnetization unit, the first programmable switch unit, the pipeline DC demagnetization unit and the second programmable switch unit are all controlled by the programmable logic controller.

[0021] Preferably, outer surfaces of the upstream pipeline and the downstream pipeline in the interface direction are both equipped with a magnetic field intensity sensor and a temperature sensor, and the magnetic field intensity sensor and the temperature sensor are electrically connected to the programmable logic controller respectively.

[0022] Preferably, the number of temperature sensors used is 8.

[0023] Another method for using the demagnetization and heating integrated machine for long-distance oil and gas pipelines includes the following steps:

[0024] Step a: When the start button is pressed, the programmable logic controller automatically collects the magnetic field intensity data and temperature data at the pipeline weld and performs relevant logical operations;

[0025] Step b: Under the control of the programmable logic controller, the first program-controlled switch unit and the second program-controlled switch unit are disconnected, and the program-controlled switching unit is switched to the AC degaussing unit;

[0026] Step c: The programmable logic controller starts automatic AC demagnetization according to the collected magnetic field strength data until the magnetic field strength of the pipeline at the weld joint is reduced to a specified range, stops the AC demagnetization work, and gives an audible and visual prompt once;

[0027] Step d: the programmable logic controller controls the program-controlled switching unit to disconnect from the AC degaussing unit, and then controls the first program-controlled switch unit to close;

[0028] Step e: The PLC controls the DC degaussing unit to perform DC degaussing. The PLC automatically adjusts the DC output current until the magnetic field strength at the weld joint falls within the specified range, and then issues an audible and visual warning. The PLC continues to automatically adjust and control the DC degaussing unit to maintain the magnetic field strength at the weld joint within the specified range.

[0029] Step f: The programmable logic controller controls the program-controlled switching unit to switch to the pipeline medium frequency heating unit, and connects the pipeline medium frequency heating unit and the second program-controlled switch unit, that is, connects the medium frequency heating cable and the medium frequency heating cable / AC degaussing cable, and heats the pipeline at the weld according to the built-in or preset heating curve until the temperature reaches the specified requirement. An audible and visual prompt is given once for a long time to remind the operator that the pipeline welding operation can be carried out; at the same time, the programmable logic controller continues to automatically adjust and control the pipeline medium frequency heating unit to maintain the temperature value at the pipeline weld within the specified range;

[0030] Step g: After the pipeline welding is completed, according to the operator's instructions, the programmable logic controller disconnects the first program-controlled switch unit and automatically adjusts and controls the pipeline medium-frequency heating unit to perform insulation and cooling work on the pipeline at the weld according to the built-in or preset insulation and cooling curves;

[0031] Step h: After the heat preservation and cooling work is completed, the programmable logic controller disconnects the second program-controlled switch unit and the program-controlled switching unit, performs an audible and visual prompt, and then switches the device to standby mode.

[0032] Compared with existing technologies, the present invention offers the following advantages: It not only reduces equipment power consumption and pit space, but also simplifies the on-site demagnetization and heating procedures for the pipes to be welded, reducing construction time and improving work efficiency. More importantly, the present invention fundamentally eliminates the possibility of simultaneous AC demagnetization and medium-frequency heating of the pipe on the side to be welded, thereby improving the safety of the pipe welding process. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the use status of the single-sided pipeline demagnetization and heating integrated machine of the present invention.

[0034] Figure 2 This is a schematic diagram of the use status of the bilateral pipeline demagnetization and heating integrated machine of the present invention.

[0035] Figure 3 This is a schematic diagram of the use status of the existing equipment of the present invention.

[0036] Figure 4 This is the logical structure diagram of the unilateral pipeline demagnetization and heating integrated machine of the present invention (schematic diagram of the pipeline on the weld side).

[0037] Figure 5 This is the logical structure diagram of the bilateral pipeline demagnetization and heating integrated machine of the present invention.

[0038] In the figure: 1. Upstream pipeline, 2. Medium frequency heating cable / AC degaussing cable, 3. DC degaussing cable, 4. Downstream pipeline, 5. Pipeline degaussing and heating integrated machine, 6. Pipeline medium frequency heating unit, 7. Programmable switching unit, 8. Pipeline AC degaussing unit, 9. First programmable switch unit, 10. Pipeline DC degaussing unit, 11. Programmable logic controller, 12. Magnetic field strength sensor, 13. Temperature sensor, 14. Second programmable switch unit, 15. Medium frequency heating cable. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] Example 1: Please refer to Figure 1 、 Figure 3 and Figure 4 The present invention provides a technical solution: a long-distance oil and gas pipeline demagnetization and heating integrated machine, comprising a demagnetization and heating integrated machine 5 and an upstream pipeline 1 and a downstream pipeline 4 to be welded, wherein the inner and outer sides of the outer surfaces of the upstream pipeline 1 and the downstream pipeline 4 are respectively wound with a medium-frequency heating cable / AC demagnetization cable 2 and a DC demagnetization cable 3, and the input ends of the two sets of medium-frequency heating cables / AC demagnetization cables 2 and DC demagnetization cables 3 are each electrically connected to a set of pipeline demagnetization and heating integrated machine 5 that integrates pipeline demagnetization and pipeline heating functions;

[0041] The present invention optimizes and integrates the two original separate devices, reduces the size of the space occupied in the pipeline welding pit, and reduces part of the earth excavation cost;

[0042] Through optimization and integration, the total power of the original "pipeline heating" and "pipeline degaussing" equipment was reduced, thereby reducing the demand for the total load of mobile power generation equipment on the construction site;

[0043] It simplifies the process of demagnetizing and heating the pipes at the weld joints, reduces construction time and improves construction efficiency;

[0044] In the original pipeline heating and demagnetization method, each construction team needed to be equipped with at least two pipeline medium-frequency heating devices and two pipeline demagnetization devices, and each construction unit was equipped with multiple pipeline medium-frequency heating devices and pipeline demagnetization devices. Through this invention, the "two" separate devices are optimized and integrated into one device, reducing the total number of devices that the construction unit needs to maintain and manage, thereby reducing operating costs.

[0045] When heating and demagnetizing a pipe on one side of a weld, it is strictly forbidden to operate "medium frequency heating" and "AC demagnetization" at the same time, otherwise equipment damage or even casualties may occur. The present invention uses an optimized design to share the same set of cables for medium frequency heating and AC demagnetization of the pipeline. Moreover, due to the design of the programmable switching unit 7 and the programmable logic controller 11, this phenomenon is fundamentally eliminated in terms of physical structure and logical control. Whether the programmable switching unit 7 is in normal operation or in an abnormal fault state, it is impossible for the medium frequency heating / AC demagnetization cable 2 to be connected to the pipeline medium frequency heating unit 6 and the pipeline AC demagnetization unit 8 at the same time. Moreover, the programmable logic controller 11 detects the working status of the programmable switching unit 7 in real time to ensure that the "demagnetization" and "heating" operations are performed in the correct steps, thereby improving the safety of on-site construction.

[0046] Specifically, the pipeline demagnetization and heating integrated machine 5 includes a pipeline medium frequency heating unit 6, a programmable switching unit 7, a pipeline AC demagnetization unit 8, a first programmable switch unit 9, a pipeline DC demagnetization unit 10 and a programmable logic controller 11; the transmission and reception of electrical signals and control signals of the pipeline medium frequency heating unit 6, the programmable switching unit 7, the pipeline AC demagnetization unit 8, the first programmable switch unit 9 and the pipeline DC demagnetization unit 10 are all controlled by the programmable logic controller 11.

[0047] Specifically, the outer surfaces of the upstream pipeline 1 and the downstream pipeline 4 in the interface direction are both equipped with a magnetic field intensity sensor 12 and a temperature sensor 13 , and the magnetic field intensity sensor 12 and the temperature sensor 13 are electrically connected to the programmable logic controller 11 respectively.

[0048] Specifically, eight temperature sensors 13 are used, which are respectively installed near the inner ends of the upstream pipe 1 and the downstream pipe 4 for monitoring the temperature at the weld joint.

[0049] A method for using a solution based on a demagnetization and heating integrated machine for long-distance oil and gas pipelines includes the following steps:

[0050] Step a: When the start button is pressed, the programmable logic controller 11 automatically collects the magnetic field intensity data 12 and the temperature data 13 at the pipeline weld, and performs relevant logical operations;

[0051] Step b: Under the control of the programmable logic controller 11, the first program-controlled switch unit 9 is disconnected, and the program-controlled switching unit 7 is switched to the AC degaussing unit 8;

[0052] Step c: The programmable logic controller 11 starts automatic AC demagnetization according to the collected magnetic field strength data until the magnetic field strength of the pipeline at the weld joint decreases to a specified range, stops the AC demagnetization, and performs an audible and visual prompt;

[0053] Step d: the programmable logic controller 11 controls the program-controlled switching unit 7 to disconnect from the AC degaussing unit 8, and then controls the first program-controlled switch unit 9 to close;

[0054] Step e: The programmable logic controller 11 controls the DC degaussing unit 10 to perform DC degaussing. The programmable logic controller 11 automatically adjusts the DC output current until the magnetic field strength at the weld joint falls within a specified range, and then issues an audible and visual warning. The programmable logic controller 11 continues to automatically adjust and control the DC degaussing unit 10 to maintain the magnetic field strength at the weld joint within the specified range.

[0055] Step f: The programmable logic controller 11 controls the program-controlled switching unit 7 to switch the medium-frequency heating cable / AC degaussing cable 2 to the pipeline medium-frequency heating unit 6, and heats the pipeline at the weld according to the built-in or preset temperature rise curve until the temperature reaches the specified requirement. An audible and visual prompt is given once for a long time to remind the operator that the pipeline welding operation can be carried out; at the same time, the programmable logic controller 11 continues to automatically adjust and control the pipeline medium-frequency heating unit 6 to maintain the temperature value at the pipeline weld within the specified range;

[0056] Step g: After the pipeline welding is completed, according to the operator's instructions, the programmable logic controller 11 disconnects the first program-controlled switch unit 9 and automatically adjusts and controls the pipeline medium-frequency heating unit 6 to perform insulation and cooling work on the pipeline at the weld according to the built-in or preset insulation and cooling curves;

[0057] Step h: After the heat preservation and cooling work is completed, the programmable logic controller 11 disconnects the program-controlled switching unit 7, performs an audible and visual prompt, and then switches the device to the standby state.

[0058] The above operation steps are "automatic mode", and there is also a "manual mode", that is, manually operating the corresponding button to apply instructions to the programmable logic controller 11 to achieve the purpose of controlling other working units. The equipment will perform the corresponding functions completely according to the operator's instructions.

[0059] Example 2: Please refer to Figure 2 、 Figure 3 and Figure 5The present invention provides another technical solution: another solution of a long-distance oil and gas pipeline demagnetization and heating integrated machine, comprising a demagnetization and heating integrated machine 5 and an upstream pipeline 1 and a downstream pipeline 4 to be welded, wherein the outer surface of the upstream pipeline 1 is wound with a medium frequency heating cable 15, and the outer surface of the downstream pipeline 4 is wound with a medium frequency heating cable / AC demagnetization cable 2 and a DC demagnetization cable 3, and the input ends of the medium frequency heating cable / AC demagnetization cable 2, the DC demagnetization cable 3, and the medium frequency heating cable 15 are electrically connected to the pipeline demagnetization and heating integrated machine 5 that integrates the pipeline demagnetization function and the pipeline heating function;

[0060] The technical solution of this embodiment differs from that of Embodiment 1 in that it is another welding condition at the construction site of a long-distance pipeline: welding a new pipeline (section) on the original pipeline. The new pipeline (section) is basically non-magnetic or has extremely low magnetism, which is not enough to affect the welding construction. In this case, during on-site welding, only the old pipeline needs to be demagnetized and heated, and the new pipeline (section) only needs to be heated.

[0061] To meet the needs of such construction sites, the present invention proposes the technical solution of Example 2, namely, a "double-sided pipe demagnetization and heating integrated machine" that can demagnetize the pipe on one side of the weld while also performing medium-frequency heating on the pipes on both sides of the weld. This can further simplify on-site construction steps, reduce operation time, and improve work efficiency.

[0062] Specifically, the pipeline demagnetization and heating integrated machine 5 includes a pipeline medium frequency heating unit 6, a programmable switching unit 7, a pipeline AC demagnetization unit 8, a first programmable switch unit 9, a pipeline DC demagnetization unit 10, a programmable logic controller 11 and a second programmable switch unit 14; the transmission and reception of electrical signals and control signals of the pipeline medium frequency heating unit 6, the programmable switching unit 7, the pipeline AC demagnetization unit 8, the first programmable switch unit 9, the pipeline DC demagnetization unit 10 and the second programmable switch unit 14 are all controlled by the programmable logic controller 11.

[0063] Specifically, the outer surfaces of the upstream pipeline 1 and the downstream pipeline 4 in the interface direction are both equipped with a magnetic field intensity sensor 12 and a temperature sensor 13 , and the magnetic field intensity sensor 12 and the temperature sensor 13 are electrically connected to the programmable logic controller 11 respectively.

[0064] Specifically, eight temperature sensors 13 are used, which are respectively mounted on the inner ends of the upstream pipe 1 and the downstream pipe 4 to detect the temperatures at the welds at both ends.

[0065] Another method for using the demagnetization and heating integrated machine for long-distance oil and gas pipelines includes the following steps:

[0066] Step a: When the start button is pressed, the programmable logic controller 11 automatically collects the magnetic field strength data 12 and the temperature data 13 at the pipeline weld, and performs relevant logical operations;

[0067] Step b: Under the control of the programmable logic controller 11, the first programmable switch unit 9 and the second programmable switch unit 14 are disconnected, and the programmable switching unit 7 is switched to the AC degaussing unit 8;

[0068] Step c: The programmable logic controller 11 starts automatic AC demagnetization according to the collected magnetic field strength data until the magnetic field strength of the pipeline at the weld joint decreases to a specified range, stops the AC demagnetization, and performs an audible and visual prompt;

[0069] Step d: the programmable logic controller 11 controls the program-controlled switching unit 7 to disconnect from the AC degaussing unit 8, and then controls the first program-controlled switch unit 9 to close;

[0070] Step e: The programmable logic controller 11 controls the DC degaussing unit 10 to perform DC degaussing. The programmable logic controller 11 automatically adjusts the DC output current until the magnetic field strength at the weld joint falls within a specified range, and then issues an audible and visual warning. The programmable logic controller 11 continues to automatically adjust and control the DC degaussing unit 10 to maintain the magnetic field strength at the weld joint within the specified range.

[0071] Step f: The programmable logic controller 11 controls the program-controlled switching unit 7 to switch to the pipeline intermediate frequency heating unit 6, and connects the pipeline intermediate frequency heating unit 6 to the second program-controlled switch unit 14, that is, connects the intermediate frequency heating cable 15 and the intermediate frequency heating cable / AC degaussing cable 2, and heats the pipeline at the weld according to the built-in or preset heating curve until the temperature reaches the specified requirement. A long sound and light prompt is given once to remind the operator that the pipeline welding operation can be carried out; at the same time, the programmable logic controller 11 continues to automatically adjust and control the pipeline intermediate frequency heating unit 6 to keep the temperature value at the pipeline weld within the specified range;

[0072] Step g: After the pipeline welding is completed, according to the operator's instructions, the programmable logic controller 11 disconnects the first program-controlled switch unit 9 and automatically adjusts and controls the pipeline medium-frequency heating unit 6 to perform insulation and cooling work on the pipeline at the weld according to the built-in or preset insulation and cooling curves;

[0073] Step h: After the heat preservation and cooling work is completed, the programmable logic controller 11 disconnects the second program-controlled switch unit 14 and the program-controlled switching unit 7, performs an audible and visual prompt, and then switches the device to the standby state.

[0074] The above operation steps are "automatic mode", and there is also a "manual mode", that is, manually operating the corresponding button to apply instructions to the programmable logic controller 11 to achieve the purpose of controlling other working units. The equipment will perform the corresponding functions completely according to the operator's instructions.

[0075] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0076] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A long-distance oil and gas pipeline demagnetization and heating integrated machine, comprising a pipeline demagnetization and heating integrated machine (5) and an upstream pipeline (1) and a downstream pipeline (4) to be welded, characterized in that: The inner and outer sides of the outer surfaces of the upstream pipeline (1) and the downstream pipeline (4) are respectively wound with a medium frequency heating cable / AC degaussing cable (2) and a DC degaussing cable (3); the input ends of the two sets of the medium frequency heating cable / AC degaussing cable (2) and the DC degaussing cable (3) are each electrically connected to a set of pipeline degaussing and heating all-in-one machine (5) that integrates pipeline degaussing and pipeline heating functions; The pipeline demagnetization and heating integrated machine (5) comprises: a pipeline medium frequency heating unit (6), a program-controlled switching unit (7), a pipeline AC demagnetization unit (8), a first program-controlled switch unit (9), a pipeline DC demagnetization unit (10), and a programmable logic controller (11); the transmission and reception of electrical signals and the transmission and reception of control signals of the pipeline medium frequency heating unit (6), the program-controlled switching unit (7), the pipeline AC demagnetization unit (8), the first program-controlled switch unit (9), and the pipeline DC demagnetization unit (10) are all controlled by the programmable logic controller (11).

2. A long-distance oil and gas pipeline demagnetization and heating integrated machine, comprising a pipeline demagnetization and heating integrated machine (5) and an upstream pipeline (1) and a downstream pipeline (4) to be welded, characterized in that: The outer surface of the upstream pipeline (1) is wound with a medium frequency heating cable (15), and the outer surface of the downstream pipeline (4) is wound with a medium frequency heating cable / AC degaussing cable (2) and a DC degaussing cable (3), and the input ends of the medium frequency heating cable / AC degaussing cable (2), the DC degaussing cable (3) and the medium frequency heating cable (15) are electrically connected to a pipeline degaussing and heating all-in-one machine (5) that integrates pipeline degaussing and pipeline heating functions. The pipeline demagnetization and heating integrated machine (5) comprises: a pipeline medium frequency heating unit (6), a programmable switching unit (7), a pipeline AC demagnetization unit (8), a first programmable switch unit (9), a pipeline DC demagnetization unit (10), a programmable logic controller (11), and a second programmable switch unit (14); the transmission and reception of electrical signals and the transmission and reception of control signals of the pipeline medium frequency heating unit (6), the programmable switching unit (7), the pipeline AC demagnetization unit (8), the first programmable switch unit (9), the pipeline DC demagnetization unit (10), and the second programmable switch unit (14) are all controlled by the programmable logic controller (11).

3. The integrated demagnetization and heating machine for long-distance oil and gas pipelines according to claim 1 or 2, characterized in that: The outer surfaces of the upstream pipeline (1) and the downstream pipeline (4) in the interface direction are both equipped with a magnetic field intensity sensor (12) and a temperature sensor (13), and the magnetic field intensity sensor (12) and the temperature sensor (13) are respectively electrically connected to a programmable logic controller (11).

4. The integrated demagnetization and heating machine for long-distance oil and gas pipelines according to claim 3 is characterized by: The number of temperature sensors (13) used is 8.

5. The method for using the long-distance oil and gas pipeline demagnetization and heating integrated machine according to claim 1 is characterized in that The following method: Step a: When the start button is pressed, the programmable logic controller (11) automatically collects the magnetic field intensity data and temperature data at the pipeline weld, and performs relevant logical operations; Step b: under the control of the programmable logic controller (11), the first program-controlled switch unit (9) is disconnected, and the program-controlled switching unit (7) is switched to the AC demagnetization unit (8); Step c: the programmable logic controller (11) starts automatic AC demagnetization according to the collected magnetic field strength data until the magnetic field strength of the pipeline at the weld joint is reduced to a specified range, stops the AC demagnetization work, and performs an audible and visual prompt once; Step d: the programmable logic controller (11) controls the program-controlled switching unit (7) to disconnect from the AC degaussing unit (8), and then controls the first program-controlled switch unit (9) to close; Step e: the programmable logic controller (11) controls the DC demagnetization unit (10) to perform DC demagnetization. The programmable logic controller (11) automatically adjusts the DC output current value until the magnetic field intensity value of the pipeline at the weld joint decreases to within a specified range, and performs an audible and visual prompt once. The programmable logic controller (11) continues to automatically adjust and control the DC demagnetization unit (10) to maintain the magnetic field intensity value at the pipeline weld joint within the specified range. Step f: The programmable logic controller (11) controls the program-controlled switching unit (7) to switch the medium-frequency heating cable / AC degaussing cable (2) to the pipeline medium-frequency heating unit (6), and performs a temperature increase operation at the weld joint according to a built-in or preset temperature increase curve until the temperature reaches a specified requirement, and then performs an acoustic and visual prompt once for a long time to prompt the operator to perform the pipeline welding operation; at the same time, the programmable logic controller (11) continues to automatically adjust and control the pipeline medium-frequency heating unit (6) to maintain the temperature value at the pipeline weld joint within a specified range; Step g: After the pipeline welding is completed, according to the operator's instructions, the programmable logic controller (11) disconnects the first program-controlled switch unit (9) and automatically adjusts and controls the pipeline medium-frequency heating unit (6) to perform insulation and cooling work on the pipeline at the weld according to the built-in or preset insulation and cooling curves; Step h: After the heat preservation and cooling work is completed, the programmable logic controller (11) disconnects the program-controlled switching unit (7), performs an audible and visual prompt, and then switches the device to a standby state.

6. The method for using the long-distance oil and gas pipeline demagnetization and heating integrated machine according to claim 2 is characterized in that The following method: Step a: When the start button is pressed, the programmable logic controller (11) automatically collects the magnetic field intensity data and temperature data at the pipeline weld, and performs relevant logical operations; Step b: under the control of the programmable logic controller (11), the first programmable switch unit (9) and the second programmable switch unit (14) are disconnected, and the programmable switching unit (7) is switched to the AC demagnetization unit (8); Step c: the programmable logic controller (11) starts automatic AC demagnetization according to the collected magnetic field strength data until the magnetic field strength of the pipeline at the weld joint is reduced to a specified range, stops the AC demagnetization work, and performs an audible and visual prompt once; Step d: the programmable logic controller (11) controls the program-controlled switching unit (7) to disconnect from the AC degaussing unit (8), and then controls the first program-controlled switch unit (9) to close; Step e: the programmable logic controller (11) controls the DC demagnetization unit (10) to perform DC demagnetization. The programmable logic controller (11) automatically adjusts the DC output current value until the magnetic field intensity value of the pipeline at the weld joint decreases to within a specified range, and performs an audible and visual prompt once. The programmable logic controller (11) continues to automatically adjust and control the DC demagnetization unit (10) to maintain the magnetic field intensity value at the pipeline weld joint within the specified range. Step f: The programmable logic controller (11) controls the program-controlled switching unit (7) to switch to the pipeline medium frequency heating unit (6), and then switches on the second program-controlled switch unit (14), that is, switches on the medium frequency heating cable (15) and the medium frequency heating cable / AC degaussing cable (2), and performs a pipeline heating operation at the weld according to a built-in or preset heating curve until the temperature reaches the specified requirement, and performs a long-term sound and light prompt once to prompt the operator to perform the pipeline welding operation; at the same time, the programmable logic controller (11) continues to automatically adjust and control the pipeline medium frequency heating unit (6) to keep the temperature value at the pipeline weld within the specified range; Step g: After the pipeline welding is completed, according to the operator's instructions, the programmable logic controller (11) disconnects the first program-controlled switch unit (9) and automatically adjusts and controls the pipeline medium-frequency heating unit (6) to perform insulation and cooling work on the pipeline at the weld according to the built-in or preset insulation and cooling curves; Step h: After the heat preservation and cooling work is completed, the programmable logic controller (11) disconnects the program-controlled switching unit (7), disconnects the second program-controlled switch unit (14), performs an audible and visual prompt, and then switches the device to a standby state.

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