Telescopic pipeline electric heat tracing device

Abstract

The utility model discloses a pipeline electric heat tracing device, the pipeline electric heat tracing device heats a pipeline, the pipeline electric heat tracing device comprises a power supply device, a ferromagnet steel pipe, a skin cable, a sealing device, an insulating layer and a temperature sensor, the power supply device is electrically connected with the skin cable, the ferromagnet steel pipe is fixedly connected with the skin cable, and the sealing device is fixedly connected with the skin cable. The ferromagnetic steel pipe is fixedly connected with the sealing device, the outer side of the ferromagnetic steel pipe is sleeved with an insulating layer, the insulating layer is fixedly connected with the sealing device, the skin cable is electrically connected with the temperature sensor, and the temperature sensor is fixedly connected with the outer wall of the pipeline. The power supply equipment provides alternating current, a continuous closed circuit is formed in the ferromagnet steel pipe, an eddy current effect and a hysteresis effect are generated to dissipate heat, the sealing device stretches and retracts at the end to control the sealing performance and prevent the sealing device from making contact with outside air to dissipate heat, the insulating layer improves the heat preservation effect, and the temperature sensor on the outer wall of the pipeline monitors the temperature in real time. And signals are output for connection and disconnection.

Description

Technical Field

[0001] The utility model relates to the technical field of electric heating devices, in particular to a retractable pipeline electric heating device. Background Art

[0002] Pipelines play an important role in transporting energy, gas and liquid to meet the needs of production and life. To prevent materials from solidifying, pipelines must be insulated and anti-freeze with heating devices.

[0003] Most existing pipeline heating devices use steam heating or electric heating tape devices. However, the heat of steam gradually decreases during the transportation process, the pipeline is heated unevenly, local overheating is prone to occur, and the heat loss is large. The electric heating tape is wrapped around the pipeline, which has high energy consumption and poses a safety hazard. Considering the cost issue, the electric heating tape is more suitable for medium and short distance pipelines.

[0004] In addition, during the heating process, the temperature of the pipe is constantly changing, causing expansion, and a retractable sealing device is required to control the sealing. Summary of the invention

[0005] The utility model aims to provide a retractable pipeline electric heating device to solve the problems raised in the above background technology.

[0006] In order to solve the above technical problems, the utility model provides the following technical solutions:

[0007] A retractable pipeline electric heating device heats the pipeline. The pipeline electric heating device comprises a power supply device, a ferromagnetic steel pipe, a skin-collecting cable, a sealing device, an insulating layer and a temperature sensor. The power supply device is electrically connected to the skin-collecting cable, the ferromagnetic steel pipe and the skin-collecting cable are tightly connected, the ferromagnetic steel pipe and the sealing device are tightly connected, an insulating layer is provided on the outer side of the ferromagnetic steel pipe, the insulating layer and the sealing device are tightly connected, the skin-collecting cable and the temperature sensor are electrically connected, and the temperature sensor is installed close to the outer wall of the pipeline.

[0008] The power supply equipment is used to provide power. The power supply equipment is connected to the skin-collecting cable. The skin-collecting cable is energized and connected to the ferromagnetic steel pipe. The current flows from the beginning of the skin-collecting cable to the end, and then flows from the end of the ferromagnetic steel pipe to the beginning, forming a continuous closed loop. The power supply is fed with an alternating current to generate an alternating magnetic field. The magnetic flux of the closed loop is constantly changing. The ferromagnetic steel pipe has a small body resistance. The magnetic lines of force pass through the inner wall of the ferromagnetic steel pipe to generate an induced electromotive force and an induced current. The current direction circles along the circumference of the ferromagnetic steel pipe, forming a vortex and generating an eddy current effect. According to the proximity effect of alternating current, the current is concentrated on the adjacent side of the conductor. Due to the skin effect of the current, when alternating current passes through the conductor, the current distribution inside the conductor is uneven and the current is concentrated on the surface of the conductor. The closer to the surface of the conductor, the greater the current density. As the frequency of alternating current and the magnetic permeability of the conductor material increase, the current on the conductor cross section is more concentrated on the surface of the conductor. The current flowing through the ferromagnetic steel pipe is concentrated on the inner wall surface of the ferromagnetic steel pipe to form eddy current heating. The alternating magnetic field generated by the skin cable when it is energized magnetizes the ferromagnetic steel pipe, and a hysteresis effect is generated inside the ferromagnetic steel pipe, resulting in some heat consumption.

[0009] The skin-connected cable itself is an insulated conductor, and the heat consumed is the resistance heat generated by its own power supply. Sealing devices are set at both ends of the ferromagnetic steel pipe to prevent the inside of the ferromagnetic steel pipe from contacting the air, exchanging heat with the outside world, and dissipating heat, so as to achieve a better heating effect, prevent water vapor and corrosive media from entering the inside of the ferromagnetic steel pipe, and extend the service life. The surface of the ferromagnetic steel pipe is provided with an insulating layer, which is insulated from the surrounding environment or adjacent conductors, and can prevent the internal conductor from short-circuiting with the external medium, thereby ensuring the safe operation of the circuit and achieving better insulation and anti-corrosion effects. The temperature sensor monitors the temperature on the skin-connected cable and connects to the power supply equipment to detect any faults in time and avoid overheating.

[0010] The power supply equipment includes a power box, a distribution control cabinet, and a tail box. The power box and the distribution control cabinet are electrically connected, the power box and the skin-collecting cable are electrically connected, the distribution control cabinet and the skin-collecting cable are electrically connected, the distribution control cabinet and the temperature sensor are electrically connected, and the tail box and the skin-collecting cable are electrically connected.

[0011] The power box is connected to the power distribution control cabinet. The power box provides AC power. The power distribution control cabinet plays the role of power control, protection, and monitoring to ensure the normal operation of the circuit and provide safe and stable power supply. The first section of the skin-collecting cable is connected to the power box, and the tail end is connected to the tail end box, so that the circuit is normally energized to form a continuous closed loop to generate an alternating magnetic field. The temperature sensor monitors the temperature on the skin-collecting cable. The temperature sensor is a thermistor. The temperature is measured by the change in the resistance of the thermistor with the change of temperature. It has high sensitivity and fast response speed. The output end of the temperature sensor is connected to the power distribution control cabinet, and the temperature is converted into an output signal to the power distribution control cabinet, which is turned on and off. The temperature sensor monitors the circuit and remotely collects data to keep abreast of the temperature conditions and ensure power supply safety.

[0012] The sealing device includes a sealing ring, a rubber gasket, a screw rod, a nut and a driving motor. Two sealing rings are provided, and the two sealing rings are respectively located at the two ends of the ferromagnetic steel pipe. Several screw rods are provided, and the several screw rods are evenly arranged along the circumference of the two sealing rings. The screw rod and the sealing ring are rotatably connected. Several nuts are provided, and the several nuts are threadedly connected to the screw rod. The nut and the rubber gasket are tightly connected. Several driving motors are provided, and the several driving motor casings are tightly connected to the sealing rings, and the output end of the driving motor is tightly connected to the screw rod.

[0013] The sealing ring is made of elastic rubber material. Two sealing rings are sleeved on the two ports at the head and tail of the ferromagnetic steel pipe to prevent the inside from contacting with the outside air, dissipating heat, and preventing impurities from entering the inside of the ferromagnetic steel pipe. A diamond-shaped rubber gasket is arranged around the ferromagnetic steel pipe. When the pipe expands due to heat, the rubber gasket is compressed, and a certain angle of deformation is generated as the pipe expands. Screws are arranged on the two sealing rings, and the driving motor casing is fixed on the sealing ring. The output end of the driving motor is connected to the screw, which drives the screw to rotate, driving the nut on the screw to make linear motion, and the nut is fixed on the rubber gasket. The nut is driven to drive the rubber gasket to expand and contract, thereby controlling the sealing performance under different temperatures.

[0014] The ferromagnetic steel pipe is tightly connected with two sealing rings, a sealing groove is arranged on the ferromagnetic steel pipe, the sealing ring is placed in the sealing groove, the ferromagnetic steel pipe is slidingly connected with the rubber gasket, the ferromagnetic steel pipe is rotationally connected with the lead screw, and a slide groove is arranged on the ferromagnetic steel pipe.

[0015] The sealing groove is used to install the sealing ring, which can prevent the sealing ring from sliding during the installation process, ensuring the accurate docking between the sealing ring and the surface of the ferromagnetic steel pipe. A rubber gasket is arranged in the ferromagnetic steel pipe, and the rubber gasket slides under the transmission of the nut for adjustment. A sliding groove is arranged on the ferromagnetic steel pipe to guide the sliding of the nut.

[0016] The insulating layer is tightly connected to the sealing ring, the insulating layer is rotatably connected to the lead screw, and the insulating layer is made of resin material.

[0017] The insulating layer on the outside of the ferromagnetic steel pipe is tightly connected to the sealing ring to isolate it from the outside world, prevent heat loss, improve the thermal insulation effect, and ensure the stable operation of the pipeline electric heating device.

[0018] The power supply box provides AC power.

[0019] Only when alternating current is passed can an alternating magnetic field be generated, and eddy current effect can be formed in the ferromagnetic steel pipe to generate heat.

[0020] Compared with the prior art, the beneficial effects achieved by the utility model are as follows: the utility model provides alternating current to the skin-collecting cable through the power box, the skin-collecting cable and the ferromagnetic steel pipe form a continuous closed loop, generating an alternating magnetic field, the magnetic lines of force pass through the inner wall of the ferromagnetic steel pipe to generate induced current, eddy current effect is generated inside the ferromagnetic steel pipe to generate heat, the alternating magnetic field magnetizes the ferromagnetic steel pipe, generating hysteresis effect heat, the skin-collecting cable itself is energized and heated, and the temperature sensor on the outer wall of the pipe transmits a signal to the distribution control cabinet to open and close the circuit. Sealing rings are set at both ends of the ferromagnetic steel pipe, and the ends are expanded and contracted to prevent contact with the outside air, dissipate heat, and prevent impurities from entering. A diamond-shaped rubber gasket is set around the ferromagnetic steel pipe. When the pipe expands due to heat, the rubber gasket is compressed to produce a certain angle deformation. A number of screw rods and a number of drive motors are set around the sealing ring. The drive motor casing is fixed on the sealing ring, and the output end is connected to the screw rod to drive the screw rod to rotate. The nut is fixed on the rubber gasket. The nut performs linear motion to drive the rubber gasket to expand and contract, thereby controlling the sealing performance at different temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0022] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0023] Figure 2 It is a schematic diagram of the structure of the power supply device of the utility model;

[0024] Figure 3 It is the overall front view of the utility model;

[0025] Figure 4 yes Figure 3 AA section view of the view;

[0026] Figure 5 This is a partial structural diagram of the sealing device of the utility model.

[0027] Figure 6 This is a partial structural diagram of the sealing device of the utility model.

[0028] In the figure: 1. pipeline; 2. power supply equipment; 3. ferromagnetic steel pipe; 4. skin-collecting cable; 5. sealing device; 6. insulation layer; 7. temperature sensor; 21. power supply box; 22. power distribution control cabinet; 23. tail box; 31. sealing groove; 32. slide groove; 51. sealing ring; 52. rubber gasket; 53. screw rod; 54. nut; 55. drive motor; 6. insulation layer; 7. temperature sensor. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0030] The utility model provides the following technical solutions:

[0031] like Figure 1 and Figure 4 As shown, a retractable pipeline electric heating device is used to heat the pipeline 1. The pipeline electric heating device includes a power supply device 2, a ferromagnetic steel pipe 3, a skin-collecting cable 4, a sealing device 5, an insulating layer 6 and a temperature sensor 7. The power supply device 2 is electrically connected to the skin-collecting cable 4, the ferromagnetic steel pipe 3 and the skin-collecting cable 4 are tightly connected, the ferromagnetic steel pipe 3 and the sealing device 5 are tightly connected, an insulating layer 6 is sleeved on the outer side of the ferromagnetic steel pipe 3, the insulating layer 6 and the sealing device 5 are tightly connected, the skin-collecting cable 4 and the temperature sensor 7 are electrically connected, and the temperature sensor 7 is installed close to the outer wall of the pipeline 1.

[0032] The power supply device 2 is used to provide power. The power supply device 2 is connected to the skin-collecting cable 4. The skin-collecting cable 4 is energized. The skin-collecting cable 4 is connected to the ferromagnetic steel pipe 3. The current flows from the starting end to the end of the skin-collecting cable 4, and then flows from the end to the starting end of the ferromagnetic steel pipe 3, forming a continuous closed loop. The power supply inputs an alternating current to generate an alternating magnetic field. The magnetic flux of the closed loop keeps changing. The ferromagnetic steel pipe 3 has a small body resistance. The magnetic lines of force pass through the inner wall of the ferromagnetic steel pipe 3 to generate an induced electromotive force and an induced current. The direction of the current circles along the circumference of the ferromagnetic steel pipe 3 to form a vortex and generate an eddy current effect. According to the proximity effect of alternating current, the current is concentrated on the adjacent side of the conductor. Due to the skin effect of the current, when alternating current passes through the conductor, the current distribution inside the conductor is uneven. The current is concentrated on the surface of the conductor. The closer to the conductor surface, the greater the current density. As the frequency of the alternating current and the magnetic permeability of the conductor material increase, the current on the conductor cross section is more concentrated on the conductor surface. The current flowing through the ferromagnetic steel pipe 3 is concentrated on the inner wall surface of the ferromagnetic steel pipe 3 to form eddy current heating. The alternating magnetic field generated by the power-on of the skin cable 4 magnetizes the ferromagnetic steel pipe 3, and a hysteresis effect is generated inside the ferromagnetic steel pipe 3, resulting in a portion of heat consumption. The skin cable 4 itself is an insulating conductor, and the heat consumed is the resistance heat generated by its own power-on. Sealing devices 5 are provided at both ends of the ferromagnetic steel pipe 3 to prevent the inside of the ferromagnetic steel pipe 3 from contacting the air, exchanging heat with the outside world, and dissipating heat, thereby achieving a better heating effect, preventing water vapor and corrosive media from entering the inside of the ferromagnetic steel pipe 3, and extending the service life. An insulating layer 6 is provided on the surface of the ferromagnetic steel pipe 3 to insulate it from the surrounding environment or adjacent conductors, thereby preventing the internal conductor from short-circuiting with the external medium, thereby ensuring the safe operation of the circuit and achieving a better insulation and anti-corrosion effect. The temperature sensor 7 monitors the temperature and is connected to the power supply device 2 to detect any faults in time and avoid overheating.

[0033] like Figure 2 and Figure 4 As shown, the power supply device 2 includes a power box 21, a power distribution control cabinet 22, and a tail box 23. The power box 21 is electrically connected to the power distribution control cabinet 22, the power box 21 is electrically connected to the skin-collecting cable 4, the power distribution control cabinet 22 is electrically connected to the skin-collecting cable 4, the power distribution control cabinet 22 is electrically connected to the temperature sensor 7, and the tail box 23 is electrically connected to the skin-collecting cable 4.

[0034] The power box 21 is connected to the power distribution control cabinet 22. The power box 21 provides alternating current. The power distribution control cabinet 22 plays the role of power control, protection, monitoring, etc. to ensure the normal operation of the circuit and provide safe and stable power supply. The first section of the skin cable 4 is connected to the power box 21, and the tail end is connected to the tail box 23, so that the circuit is normally energized to form a continuous closed loop to generate an alternating magnetic field. The temperature sensor 7 is a thermistor. The temperature is measured by the change of the resistance of the thermistor with the change of temperature. It has high sensitivity and fast response speed. The output end of the temperature sensor 7 is connected to the power distribution control cabinet 22, and the temperature is converted into an output signal to the power distribution control cabinet 22, and the power distribution control cabinet 22 is powered on and off. The temperature sensor 7 monitors the circuit and remotely collects data, timely grasps the temperature situation, and ensures power supply safety.

[0035] like Figure 3 and Figure 5 The sealing device 5 includes a sealing ring 51, a rubber gasket 52, a screw 53, a nut 54 and a driving motor 55. There are two sealing rings 51, which are respectively located at the two ends of the ferromagnetic steel pipe 3. There are several screws 53, which are evenly arranged along the circumference of the two sealing rings 51. The screw 53 and the sealing ring 51 are rotatably connected. There are several nuts 54, which are threadedly connected to the screw 53, and the nut 54 and the rubber gasket 52 are tightly connected. There are several driving motors 55, which are tightly connected to the housing of the driving motor 55 and the sealing ring 51, and the output end of the driving motor 55 and the screw 53 are tightly connected.

[0036] The sealing ring 51 is made of elastic rubber material. The two sealing rings 51 are sleeved on the two ports at the head and tail of the ferromagnetic steel pipe 3 to prevent the interior from contacting with the outside air, dissipating heat, and preventing impurities from entering the ferromagnetic steel pipe 3. A diamond-shaped rubber gasket 52 is arranged around the ferromagnetic steel pipe 3. When the pipeline 1 expands due to heat, the rubber gasket 52 is compressed, and a certain angle of deformation is generated as the pipeline 1 expands. A screw rod 53 is arranged on the two sealing rings 51, and the casing of the driving motor 55 is fixed on the sealing ring 51. The output end of the driving motor 55 is connected to the screw rod 53, driving the screw rod 53 to rotate, driving the nut 54 on the screw rod 53 to make linear motion, and the nut 54 is fixed on the rubber gasket 52. The nut 54 is driven to drive the rubber gasket 52 to expand and contract, thereby controlling the sealing performance under different temperatures.

[0037] like Figure 6 As shown, the ferromagnetic steel pipe 3 and two sealing rings 51 are tightly connected, a sealing groove 31 is provided on the ferromagnetic steel pipe 3, the sealing ring 51 is placed in the sealing groove 31, the ferromagnetic steel pipe 3 and the rubber gasket 52 are slidingly connected, the ferromagnetic steel pipe 3 and the screw rod 53 are rotationally connected, and a slide groove 32 is provided on the ferromagnetic steel pipe 3.

[0038] The sealing groove 31 is used to install the sealing ring 51, which can prevent the sealing ring 51 from sliding during the installation process, ensuring the accurate docking between the sealing ring 51 and the surface of the ferromagnetic steel pipe 3. A rubber gasket 52 is arranged in the ferromagnetic steel pipe 3. The rubber gasket 52 slides under the transmission of the nut 54 for adjustment. A sliding groove 32 is arranged on the ferromagnetic steel pipe 3 to guide the sliding of the nut 54.

[0039] like Figure 6 As shown, the insulating layer 6 and the sealing ring 51 are tightly connected, the insulating layer 6 and the screw rod 53 are rotatably connected, and the insulating layer 6 is made of resin material.

[0040] The insulating layer 6 on the outside of the ferromagnetic steel pipe 3 is tightly connected to the sealing ring 51 to isolate the outside world, prevent heat loss, improve the thermal insulation effect, and ensure the stable operation of the pipeline electric heating device.

[0041] The power supply box 21 provides alternating current.

[0042] Only when alternating current is passed can an alternating magnetic field be generated, and eddy current effect can be formed in the ferromagnetic steel pipe 3 to generate heat.

[0043] The working principle of the utility model is as follows: an alternating current is provided to the skin-collecting cable 4 through the power box 21, the skin-collecting cable 4 and the ferromagnetic steel pipe 3 form a continuous closed loop, generating an alternating magnetic field, and the magnetic lines of force pass through the inner wall of the ferromagnetic steel pipe 3 to generate an induced current, generating eddy current effect heating inside the ferromagnetic steel pipe 3, and the alternating magnetic field magnetizes the ferromagnetic steel pipe 3 to generate hysteresis effect heating, the skin-collecting cable 4 itself is energized and heated, and a signal is transmitted to the power distribution control cabinet 22 through the temperature sensor 7 on the outer wall of the pipeline 1 to open and close the circuit. Sealing rings 51 are provided at both ends of the ferromagnetic steel pipe 3, and the ends are expanded and retracted to prevent contact with the outside air, dissipate heat, and prevent impurities from entering. A diamond-shaped rubber gasket 52 is provided around the ferromagnetic steel pipe 3. When the pipeline 1 expands due to heat, the rubber gasket 52 is compressed to produce a certain angle deformation. A plurality of screw rods 53 and a plurality of driving motors 55 are provided around the sealing ring 51. The housing of the driving motor 55 is fixed on the sealing ring 51, and the output end is connected to the screw rod 53 to drive the screw rod 53 to rotate. The nut 54 is fixed on the rubber gasket 52. The nut 54 performs linear motion to drive the rubber gasket 52 to expand and contract, thereby controlling the sealing performance at different temperatures.

[0044] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0045] Finally, it should be noted that the above description is only a preferred embodiment of the utility model and is not intended to limit the utility model. Although the utility model is described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions recorded in the above embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A retractable pipeline electric heating device, which heats a pipeline (1), characterized in that: The pipeline electric heating device comprises a power supply device (2), a ferromagnetic steel pipe (3), a skin-collecting cable (4), a sealing device (5), an insulating layer (6) and a temperature sensor (7); the power supply device (2) and the skin-collecting cable (4) are electrically connected; the ferromagnetic steel pipe (3) and the skin-collecting cable (4) are tightly connected; the ferromagnetic steel pipe (3) and the sealing device (5) are tightly connected; an insulating layer (6) is provided on the outer side of the ferromagnetic steel pipe (3); the insulating layer (6) and the sealing device (5) are tightly connected; the skin-collecting cable (4) and the temperature sensor (7) are electrically connected; and the temperature sensor (7) and the outer wall of the pipeline (1) are tightly connected.

2. The retractable pipeline electric heating device according to claim 1, characterized in that: The power supply device (2) comprises a power supply box (21), a power distribution control cabinet (22), and a tail box (23); the power supply box (21) and the power distribution control cabinet (22) are electrically connected; the power supply box (21) and the skin-collecting cable (4) are electrically connected; the power distribution control cabinet (22) and the skin-collecting cable (4) are electrically connected; the power distribution control cabinet (22) and the temperature sensor (7) are electrically connected; and the tail box (23) and the skin-collecting cable (4) are electrically connected.

3. The retractable pipeline electric heating device according to claim 1, characterized in that: The sealing device (5) comprises a sealing ring (51), a rubber gasket (52), a screw (53), a nut (54) and a driving motor (55). Two sealing rings (51) are provided, and the two sealing rings (51) are respectively located at two ends of the ferromagnetic steel pipe (3). A plurality of screws (53) are provided, and the plurality of screws (53) are evenly arranged along the circumference of the two sealing rings (51). The screw (53) and the sealing ring (51) are rotatably connected. A plurality of nuts (54) are provided, and the plurality of nuts (54) and the screw (53) are threadedly connected. The nut (54) and the rubber gasket (52) are tightly connected. A plurality of driving motors (55) are provided, and the housings of the plurality of driving motors (55) are tightly connected to the sealing ring (51), and the output end of the driving motor (55) is tightly connected to the screw (53).

4. The retractable pipeline electric heating device according to claim 3 is characterized in that: The ferromagnetic steel pipe (3) and the two sealing rings (51) are tightly connected, a sealing groove (31) is provided on the ferromagnetic steel pipe (3), the sealing ring (51) is placed in the sealing groove (31), the ferromagnetic steel pipe (3) and the rubber gasket (52) are slidably connected, the ferromagnetic steel pipe (3) and the screw rod (53) are rotatably connected, a sliding groove (32) is provided on the ferromagnetic steel pipe (3), and the ferromagnetic steel pipe (3) and the nut (54) are slidably connected.

5. The retractable pipeline electric heating device according to claim 3 is characterized in that: The insulating layer (6) and the sealing ring (51) are tightly connected, the insulating layer (6) and the screw rod (53) are rotatably connected, and the insulating layer (6) is made of resin material.

6. The retractable pipeline electric heating device according to claim 2, characterized in that: The power supply box (21) provides alternating current.

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