CN116101835A - Equipment and systems for threading electrical cables into thin tubes attached to electrically heated pipes - Google Patents

Abstract

The invention relates to a device and a system for penetrating a cable into a thin pipe attached to an electrically heated pipeline, which solve the problems of low efficiency, high threading difficulty and the like in the prior art. The system is composed of a plurality of threading devices, a plurality of pairs of pulleys, guide heads and the like. The effect is that: each threading equipment can be detached from the pipeline under the condition that the cable moves, is carried manually by a special knapsack assembly, is then mounted on the pipeline in front to wait for arrival of the cable, and forms a mode that a plurality of threading equipment are arranged along the pipeline in a multipoint mode and are threaded in a relay mode, so that the efficient and feasible threading purpose is achieved.

Description

Equipment and systems for threading electrical cables into thin tubes attached to electrically heated pipes

technical field

The invention belongs to the field of cable threading thin tubes, in particular to a device and system for threading cable lines into thin tubes attached to electrically heated pipelines.

Background technique

Oil fields in inland areas are far away from ports or refineries, and pipelines are used to transport crude oil from oil fields to ports or refineries. Due to the long distance, the temperature of the crude oil will decrease during the flow process, and the viscosity of the crude oil will increase, resulting in a decrease in the fluidity of the crude oil, and it is necessary to increase the temperature of the crude oil. Usually electric heating is used to heat the oil pipeline. Heating cables are arranged on the outer arc surface of the oil pipeline and heated by electricity. At the same time, it is necessary to insulate the pipeline, heating cables and thin tubes attached to the pipeline. The heating cable is inserted into the thin tube, and the thin tube is close to the oil pipeline, and the outermost layer is wrapped by an insulating layer.

One of the above-mentioned pipeline laying methods with a thick insulation layer is to process the oil pipeline in sections in the factory; each section of the oil pipeline is attached with a thin tube for passing through the heating cable, and then it is passed through the foaming process in the factory. Create insulation. Then transport each section of pipeline with thin tube and insulation layer to the site for welding and installation of long-distance continuous oil pipeline. Leave 200-300 mm of exposed oil pipeline at both ends of each section of pipeline, leaving room for the on-site welding of pipelines and the insertion of thin pipes for cables. After the oil pipeline is welded, the oil pipeline is continuous, but the insulation layer and the thin tube passing through the heating cable are discontinuous. The length of the discontinuity is usually twice the above-mentioned exposed length of 200-300 mm, that is, the exposed length is 400-600 mm.

The heating cable is usually a single thread threaded into a thin tube attached to the oil pipeline. In a three-phase AC power supply system, there are usually three heating cables, and the three thin tubes attached to the oil pipeline are arranged separately on the outer arc surface of the oil pipeline.

Traditionally, the method of passing heating cables into thin tubes is done manually. The construction method is: at each interval, the personnel are arranged at the intervals of the 400-600 mm insulation layer and thin tubes. Command all personnel equipped along the pipeline to push or pull the cable simultaneously by command. Or the steel wire rope traction line is penetrated in the capillary by manual method first, then the steel wire rope and the cable are connected together, and the traction line is pulled back with a threading machine similar to a hoist to complete the construction of the cable line. Along with the lengthening of the continuous non-joint length of heating cable, as more than 1 kilometer, it becomes difficult to manually wear the cable (many people need, the long line is not easy to command, the construction cost is high, and the efficiency is low). Adopt the method of hoist traction, when the continuous heating cable line without joint is very long, under the situation that there are many bends of pipeline, it is even impossible to successfully traction. Because the friction force between the cable over 1 km and the inner wall of the thin tube is so large, the force per unit area on the cable has far exceeded the limit of the pulling force per unit area of the cable specified by GB 50168-2018 .

Contents of the invention

The purpose of the present invention is to solve the above-mentioned problems in the prior art and provide a device and system for threading cables into thin tubes attached to electrically heated pipes. The equipment, construction methods and technologies for threading power cables, optical fibers and communication lines are different. The equipment and system involved in the present invention can conveniently thread continuous and uninterrupted heating cables into thin tubes, which is greatly improved compared with manual threading methods. In order to improve the efficiency, it can avoid the huge friction force with the thin tube, and can easily penetrate into the thin tube.

The above-mentioned technical purpose of the present invention is mainly solved by the following technical solutions: the equipment for threading the cable wire into the thin tube attached to the electrically heated pipeline, characterized in that the equipment is a threading device, and the threading device is at least one Each set of threading equipment includes a base, a pair of motors that are detachably arranged on the base, each of the motors is provided with a cable clamping drive wheel, and the two cables clamp The transmission wheels are set opposite to each other, and are used for clamping and conveying the cables, and a wireless switch is arranged on the motor, and the wireless switch is used for receiving a control signal, and is used for controlling the motor to start or stop.

The idea of the present invention to solve the problem is: use machines (threading equipment) instead of people, use the 400-600 mm operating space on the pipeline, place a threading equipment at intervals, and then use the wireless transmission controller of the switch to send the signal Provide a wireless switch to control the start or stop of the motor, so that multiple threading equipment along the electric heating pipeline can start and stop at the same time. In the construction of traditional threading machine, the force of one point of the end of the cable is distributed to multiple points, so as to ensure that the cable is not damaged during the construction process, and multiple cables can be threaded at the same time (each cable is matched with multiple threading machines) equipment, can work at the same time, greatly improving work efficiency). Since the length of the cable that can be pushed in the thin tube is much smaller than the length that can be pulled, it is also necessary to use a plurality of threading devices to alternately move the relay to complete the threading.

The threading system of the present invention is composed of a plurality of threading devices, and each thin tube cooperates with a plurality of threading devices, which are quickly combined and installed on site. Before the cables reach the current threading device, the threading device is installed on the electrically heated pipeline. When the cable is clamped by a pair of cable clamping transmission wheels, the motor is started under the control of the switch wireless receiver, and a pulling force is formed on the cable at the outlet end of the thin tube to pull the cable out of the thin tube ; A thrust is formed at the entrance section of the thin tube, and the cable is pushed in from the entrance of the thin tube. When the cable is pushed forward for a certain distance, it will be relayed by the threading equipment that has been installed in the front and is in a waiting state. The current threading equipment can be removed from the pipeline under the condition that the cable line moves, and a single person can carry it and transfer it to the forward relay. Because the resistance of pushing the cable in the thin tube is much greater than the resistance of pulling the cable, so try to make the threading device in the state of pulling the cable. The distance to push the cable is short, but there must be a process of pushing the cable to move in the thin tube. The distance that the cable moves in the thin tube depends on the tension of the cable itself and the smoothness of the inner wall of the thin tube.

In order to facilitate the clamping of cables, a groove ring is provided on the wheel surface of the cable clamping transmission wheel, and the groove ring is arranged along the circumferential direction of the wheel surface. The outer diameter of the cable wire is adapted.

In order to prevent the cable from slipping, the concave surface of the groove ring has thread-shaped teeth or thread-shaped tooth grooves, and the thread-shaped teeth or thread-shaped tooth grooves are perpendicular to the axis of the cable to be conveyed. The teeth or threaded tooth grooves are used to increase the frictional force, so that the two opposite cable clamping and driving wheels can clamp and transport the cables.

The two motors are connected by a hinge, and the power source of the motors is a mobile power supply. Each set of threading equipment is provided with a carrying assembly, and the carrying assembly is used to carry and move the threading equipment. Hinge connection makes it easy to adjust the angle of the two motors, so that the distance between the two cable clamping transmission wheels can be adjusted, and it is convenient to clamp cables with different diameters.

A supporting mechanism is set on each motor, and the supporting mechanism is used to support and be detachably fixed on the upper surface of the base, the base is an arc-shaped base, and the lower surface of the base is Buckled on the outer arc surface of the heated pipe.

As a preference, the base is equipped with an inverted "L-shaped" block, and the support mechanism is an L-shaped hook block. The inverted "L-shaped" block is hooked with the L-shaped hook block, so that the The motor is detachably fixed on the base.

A binding rope (usually a steel wire rope) is fitted on the base, and a length adjustment mechanism is arranged on the binding rope. The binding rope is used to bind the base on the electrically heated pipeline. The adjustment mechanism uses For adjusting the radius of curvature of the base, it is used to adjust the gap between the clamping transmission wheels relative to the cables, that is, when the radius of curvature of the base is small, the cables on the two opposite motors The gap between the clamping drive wheels is large, and the clamping force on the cable is small; when the radius of curvature of the base is large, the gap between the cable clamping drive wheels on the two opposite motors is small, Strong clamping force on cables.

The system for threading cables into thin tubes attached to electrically heated pipes includes the above-mentioned equipment for threading cables into thin tubes attached to electrically heated pipes, and also includes a detachable pair of pulleys, said The pair of pulleys is arranged at the entrance of the thin tube, and is used for enabling the cable to smoothly pass through the entrance of the thin tube.

A system for threading cables into thin tubes attached to electrically heated pipes, and also includes a tapered guide head, which is used to fix the head of each cable so that the cables run toward the thin tube When pushed in, it can smoothly avoid the steps of the adjacent but misplaced thin tube nozzles.

The system for threading cables into thin tubes attached to the electrically heated pipeline also includes a wireless switch value, and several pairs of the devices are respectively fixed on the heated pipeline along the corresponding positions of the heated pipeline, and the multiple The motors at the positions can be controlled by wireless switches, so that the cable clamping and driving wheels at multiple positions simultaneously pull or push the cables to move forward or backward.

The present invention has beneficial effects: threading cables by simulating manual threading greatly improves threading efficiency, avoids the generation of huge friction between long-distance cables and pipes, and can thread cables conveniently and efficiently Wire.

Description of drawings

Fig. 1 is a structural schematic diagram of a set of threading equipment involved in the present invention.

Detailed ways

The technical solutions of the present invention will be further specifically described below through the embodiments and in conjunction with the accompanying drawings.

Embodiment: as shown in Figure 1, the equipment for threading the cable wires into the capillaries attached to the electrically heated pipeline, the equipment is threading equipment, and the threading equipment is at least one group, and each group of the threading equipment includes The base 7 is detachably arranged on the base in pairs of motors (usually low-speed high-torque motors 1), each of which is provided with a cable clamping drive wheel 2, and the two wires The cable clamping drive wheels are set opposite to each other for clamping and conveying the cables. The motor is provided with a wireless switch for receiving control signals and controlling the motor to start or stop.

The idea of the present invention to solve the problem is: use machines (threading equipment) instead of people, use the 400-600 mm operating space on the pipeline, place a threading equipment at intervals, and then use the wireless transmission controller of the switch to send the signal Provide a wireless switch to control the start or stop of the motor, so that multiple threading equipment along the electric heating pipeline can start and stop at the same time. In the construction of traditional threading machine, the force of one point of the end of the cable is distributed to multiple points, so as to ensure that the cable is not damaged during the construction process, and multiple cables can be threaded at the same time (each cable is matched with multiple threading machines) equipment, can work at the same time, greatly improving work efficiency). Since the length of the cable that can be pushed in the thin tube is much smaller than the length that can be pulled, it is also necessary to use a plurality of threading devices to alternately move the relay to complete the threading.

The threading system of the present invention is composed of a plurality of threading devices, and each thin tube cooperates with a plurality of threading devices, which are quickly combined and installed on site. Before the cables reach the current threading device, the threading device is installed on the electrically heated pipeline. When the cable is clamped by a pair of cable clamping transmission wheels, the motor is started under the control of the switch wireless receiver, and a pulling force is formed on the cable at the outlet end of the thin tube to pull the cable out of the thin tube ; A thrust is formed at the entrance section of the thin tube, and the cable is pushed in from the entrance of the thin tube. When the cable is pushed forward for a certain distance, it will be relayed by the threading equipment that has been installed in the front and is in a waiting state. The current threading equipment can be removed from the pipeline under the condition that the cable line moves, and a single person can carry it and transfer it to the forward relay. Because the resistance of pushing the cable in the thin tube is much greater than the resistance of pulling the cable, so try to make the threading device in the state of pulling the cable. The distance to push the cable is short, but there must be a process of pushing the cable to move in the thin tube. The distance that the cable moves in the thin tube depends on the tension of the cable itself and the smoothness of the inner wall of the thin tube.

In order to clamp the cables conveniently, the wheel surface of the cable clamping transmission wheel is provided with a groove ring 21, the groove ring is arranged along the circumferential direction of the wheel surface, and the concave diameter of the groove ring is consistent with the Adapt to the outer diameter of the cable.

In order to prevent the cable from slipping, the concave surface of the groove ring has thread-shaped teeth or thread-shaped tooth grooves, and the thread-shaped teeth or thread-shaped tooth grooves are perpendicular to the axis of the cable to be conveyed. The teeth or threaded tooth grooves are used to increase the frictional force, so that the two opposite cable clamping and driving wheels can clamp and transport the cables.

The two motors are connected by a hinge 3. The power supply of the motors is a mobile power supply. A power supply socket 8 is usually arranged on the motor. The power supply socket 8 is used to form a connection with the mobile power supply. Each group of threading equipment is provided with a back assembly. The carrying assembly is used to carry and move the threading equipment. Hinge connection makes it easy to adjust the angle of the two motors, so that the distance between the two cable clamping transmission wheels can be adjusted, and it is convenient to clamp cables with different diameters.

All set support mechanism 4 on each described motor, described support mechanism is used for supporting and is detachably fixed on the upper surface of described base, and described base is arc-shaped base, and the bottom of described base The surface buckles on the outer arc surface of the heated pipe.

As preferably, the base 7 is equipped with an inverted "L-shaped" block 5, and the support mechanism is that the inverted "L-shaped" block of the L-shaped hook is engaged with the hook of the L-shaped hook, so that The motor is detachably fixed on the base. The inverted "L-shaped" block 5 can be arranged in pairs along the arc surface of the base 7, and a pair of electric motors and their cables clamping transmission wheels stand on each pair of inverted "L-shaped" blocks 5. They are arranged separately on the arc surface, and ensure that the adjacent pair of motors and their cable clamping transmission wheels do not interfere with each other, and the moving cables are connected with the adjacent pair of motors and their cable clamping transmission wheels. And support feet also do not interfere with each other.

A binding rope 6 (usually a steel wire rope) is matched on the base, and a length adjustment mechanism is set on the binding rope (screw rods are usually arranged on the steel rope to adjust the length of the steel rope), and the binding rope is used to bind the base Bundled on the electrically heated pipe, the adjustment mechanism is used to adjust the radius of curvature of the base, and is used to adjust the gap between the clamping drive wheels relative to the cable, that is, when the curvature of the base If the radius is small, the gap between the cable clamping drive wheels on the two opposite motors is large, and the clamping force on the cable is small; when the radius of curvature of the base is large, the two relative motors will The gap between the cable clamping and driving wheels on the top is small, and the clamping force on the cable is large.

The system for threading cables into thin tubes attached to electrically heated pipes includes the above-mentioned equipment for threading cables into thin tubes attached to electrically heated pipes, and also includes a detachable pair of pulleys, said The pair of pulleys is arranged at the entrance of the thin tube, and is used for enabling the cable to smoothly pass through the entrance of the thin tube.

A system for threading cables into thin tubes attached to electrically heated pipes, and also includes a tapered guide head, which is used to fix the head of each cable so that the cables run toward the thin tube When pushed in, it can smoothly avoid the steps of the adjacent but misplaced thin tube nozzles.

The system for threading cables into thin tubes attached to the electrically heated pipeline also includes a wireless switch value, and several pairs of the devices are respectively fixed on the heated pipeline along the corresponding positions of the heated pipeline, and the multiple The motors at the positions can be controlled by wireless switches, so that the cable clamping and driving wheels at multiple positions simultaneously pull or push the cables to move forward or backward.

The above scheme is further described in detail. The threading equipment of the present invention is bound on the thick pipeline that needs electric heating with a steel wire rope, and the cable is to be threaded into the thin tube attached to the pipeline that needs electric heating.

During the movement of the cable, the threading equipment can be removed from the thick heated pipe; the control signal is transmitted through the controller, and the wireless switch is used to receive the control signal, which is used to control the start or stop of the motor, so that multiple pairs of motors and And the cable clamping and driving wheel can be wirelessly controlled, so that each threading device can work at the same time according to the command. The entrance of each thin tube is equipped with a pulley device; the end of each cable is equipped with a guide head.

The device and system of the present invention can not only push the heating cable into the thin tube, but also pull the cable out of the thin tube.

The cable threading system of the present invention imitates manual threading, and uses a plurality of threading devices to relay section by section on the pipeline to complete the heating cable threading construction.

The inverted "L-shaped" block 5 can be arranged in pairs along the arc surface of the base 7, and a pair of electric motors and their cables clamping transmission wheels stand on each pair of L-shaped blocks. The inverted "L-shaped" stopper 5 is arranged separately on the arc surface, and ensures that the adjacent pair of motors and their cable clamping transmission wheels do not interfere with each other, and the moving cables and the adjacent pair of motors and Its cable clamping drive wheel and support feet also do not interfere with each other.

When the current threading device pushes the cable to the next relay threading device, it is clamped by the relay cable clamping drive wheel 2 and pulls the cable while pushing the end of the cable into the thin tube on the other hand , the current threading equipment can be removed while the cable is moving, carried to the next relay point, and installed on the pipeline to wait for the arrival of the cable.

According to the length and the weight of the cable threaded, two or more threading devices as in accompanying drawing 1 can be configured.

The distance between the two relay points is the length the threading device will be able to push the cable into the thin tube. According to the weight of the cable, the resistance of the cable and the inner wall of the thin tube in the pushed state determines the distance between the two relay points.

Since the capillary with insulation layer attached to the electrically heated pipeline is discontinuous, the two ends of each section of capillary are respectively the outlet port for pulling out the cable and the inlet port for pushing in the cable. Because the cable is transported coiled on the wire drum, the tension of the cable itself forms a small radius of curvature, and the pipe heated by electric heating is roughly straight, so the entrance of the thin tube needs to be installed to center the cable. The pulley prevents the end of the cable from abutting against the insulation layer or being stuck at the entrance, and prevents the thin wall of the thin tube from cutting the outer layer of the cable.

Since the thin tube attached to the electric heating pipe is spliced in sections, steps will be generated due to dislocation at the interface, and the steps are hidden in the insulation layer. When the ends of the cables collide with the steps, it is easy to cause the cable cannot be pushed. Therefore, it is necessary to connect a tapered guide head to the head end of the cable, so that the cable head can smoothly pass over the interface of the thin tube when being pushed, and avoid being blocked by steps.

As shown in Figure 1, a pair of threading equipment is placed horizontally, of course, it can also be placed vertically in practical applications. The horizontal or vertical placement of the motor is determined according to the diameter of the pipe to be heated and the spacing between multiple heating cables.

To illustrate the above technical solutions:

A long-distance oil pipeline (pipeline for short) project in a certain place is more than 1,000 kilometers in length, and the diameter of the oil pipeline is 600 mm. The square aluminum tube with a size of 35 mm x 30 mm is attached to the oil pipeline. The thickness of the insulation layer is 90 mm, and the distance between three square aluminum tubes in the direction of the circumferential arc of the pipeline is 150 mm, and a heating cable is inserted into each aluminum tube. Cables weigh 640 kg per kilometer. The test shows that under the condition that the thin tube is a straight line, the static friction force of a 200-meter-long cable in a square aluminum tube is 509 N. If it is required that the length of the continuous cable (without intermediate connector) is not less than 1200 meters. The static friction force of a 1200-meter-long cable in a straight aluminum tube is 3054 N. Using manual threading, one person stands every 50 meters, and 24 people are needed. Each person needs to use 160 N in the left and right directions after straightening their single arm (the thin tube is installed on the top of the pipeline, and the person stands on the side of the oil pipeline). According to previous construction experience, only one cable can be threaded every two hours. The scheme of manually threading the wire rope traction line first, and then connecting the cable with the traction line, and pulling the wire rope with a threading machine similar to a hoist is invalid and cannot be used, because the force of the cable end far exceeds the provisions of GB 50168-2018 The pull line is limited by the pulling force per unit area of the cable. If manual threading is used, the labor cost of threading construction is very high, and because the cables are too long, it is difficult to achieve common vision and unify orders. Using the equipment and system involved in the present invention, six sets of threading equipment are used for alternate relay threading, among which five sets of threading equipment are always arranged at intervals of 54 meters on the oil pipeline for threading operation, and there is always a set of threading equipment In the process of dismantling from the oil pipeline, carrying it manually and installing it on the oil pipeline. The electric motor is controlled by the wireless transmission switch control value, and six sets of threading equipment can start forward and reverse and stop at the same time. The pushing distance of the cables in the square aluminum tubes is limited to 54 meters. The motor is powered by a lithium battery pack, and the moving speed of the cable is 13 m/min. Eight people can complete three threading projects with a length of 1200 meters in two hours, which is 9 times the efficiency of manual threading.

As shown in Fig. 1, have shown the threading equipment that can thread 3 cable wires simultaneously, can thread three cable wires 9 simultaneously, the working width (pipeline axis direction) of threading apparatus is 260 millimeters. The maximum pulling force or pushing force of each pair of cable clamping and driving wheels is 510 N. When the resistance of the cable exceeds 540 N, the cable starts to slip on the cable clamping and driving wheels, but it will not touch the outer surface of the cable. damage. Once slippage is found, it may be that the cable is stuck in a certain position, and it is necessary to stop the threading inspection and eliminate the stuck point.

At the 90-degree turn of the heated pipe, it is also necessary to have a pair of pulleys fixed at the turn. This pair of pulleys must be installed before the cables arrive, and it is also required that once the threading is completed, these paired pulleys can be easily separated from the cables and removed from the pipeline.

In actual construction, because there are many places for bending pipes, it is necessary to fix a set of threading equipment at the 90-degree bend, and not participate in the alternate relay threading of multiple threading devices. It is also required that these threading devices fixed at the elbow not only have the pulling force and pushing force on the cable, but also require that the cable clamping drive wheel that clamps the cable can be separated from the cable after the threading construction is completed, and can Remove the threading device from the pipe. There are three pairs of cable clamping transmission pulleys, which can thread three cables at the same time. It is powered by a 24v lithium battery. The lithium battery, the controller and the wireless switch of the switch have a special back, which is convenient for a single person to put the battery , a controller, a wireless switch, three pairs of electric motors and their cable clamping transmission wheels, and a base with three wire ropes for carrying.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. In the above-described embodiments, various modifications and changes are possible to the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. The device is characterized in that the device is threading equipment, the threading equipment is at least one group, each group of threading equipment comprises a base, motors which are detachably arranged on the base and are arranged in pairs, each motor is provided with a cable clamping transmission wheel, the two cable clamping transmission wheels are oppositely arranged and used for clamping cables and transmitting the cables, and the motors are provided with wireless switches which are used for receiving control signals and used for controlling the motors to start or stop.

2. The apparatus for threading an electrical cable into a tubule attached to an electrically heated conduit of claim 1, wherein: the cable clamping transmission wheel is characterized in that a groove ring is arranged on the wheel surface of the cable clamping transmission wheel, the groove ring is arranged along the circumferential direction of the wheel surface, and the diameter of the inner recess of the groove ring is matched with the outer diameter of a cable to be transmitted.

3. The apparatus for threading a cable into a tubule attached to an electrically heated conduit of claim 2, wherein the concave surface of the grooved ring has a thread-like tooth or thread-like tooth slot perpendicular to the axis of the cable to be conveyed, the thread-like tooth or thread-like tooth slot being adapted to increase friction to enable two opposing cable-gripping power wheels to grip and convey the cable.

4. A device for threading an electric cable into a tubule attached to an electrically heated conduit as claimed in any one of claims 1 to 3 wherein the two motors are connected by a hinge, the power supply to the motors being a mobile power supply, and a carrying assembly is provided on each set of threading devices, the carrying assembly being adapted to carry the threading devices.

5. A device for threading an electric cable into a tubule attached to an electrically heated conduit as claimed in any one of claims 1 to 3 wherein a support means is provided on each motor for supporting and releasably securing to the upper surface of the base, the base being a circular arc base, the lower surface of the base being a snap fit over the outer circular arc surface of the heated conduit.

6. The apparatus for threading an electrical cable into a tubule attached to an electrically heated conduit of claim 5, wherein the base is provided with an inverted "L" shaped stop, and the support means is an L shaped hook block, the inverted "L" stop engaging the L shaped hook block to removably secure the motor to the base.

7. The apparatus for threading an electric cable into a tubule attached to an electrically heated conduit of claim 5, wherein the base is fitted with a binding rope having a length adjusting mechanism for binding the base to the electrically heated conduit, the adjusting mechanism being for adjusting the radius of curvature of the base for adjusting the gap between the opposing cable-gripping and transporting wheels, i.e., when the radius of curvature of the base is small, the gap between the opposing cable-gripping and transporting wheels on the motors is large and the holding force on the electric cable is small; when the curvature radius of the base is large, the gap between the cable clamping transmission wheels on the two opposite motors is small, and the clamping force on the cable is large.

8. A system for threading an electrical cable into a tubule attached to an electrically heated conduit, comprising an apparatus for threading an electrical cable into a tubule attached to an electrically heated conduit as in any one of claims 1-7, and further comprising a pair of removably disposed pulleys for positioning at the entrance of the tubule for enabling the electrical cable to pass smoothly through the entrance of the tubule.

9. The system for threading an electrical cable into a tubule attached to an electrically heated conduit of claim 8, further comprising a tapered guide head for securing to the head of each cable so that the cable can smoothly avoid the steps of adjacent but dislocated tubule orifices as it is pushed into the tubule.

10. The system of claim 9, further comprising a wireless switch, wherein the plurality of pairs of devices are disposed on the heated pipe along corresponding positions of the heated pipe, the motors being controllable by the wireless switch such that the cable grip pulley in the plurality of positions simultaneously pulls or pushes the cable in the forward or reverse direction.

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