Hot-bending elbow 3PE anti-corrosion construction system and method

Abstract

The invention relates to the technical field of hot bent pipe corrosion prevention, in particular to a hot bent pipe 3PE corrosion prevention construction system and method, and aims to solve the problems that a hot bent pipe corrosion prevention layer is poor in performance, high in corrosion prevention cost and low in efficiency. The hot bent pipe 3PE anti-corrosion construction system comprises a conveying device, a heating device, a powder spraying device, a coating device and a cooling device. The heating device is used for heating the bent pipe, and the powder spraying device is used for spraying epoxy powder on the surface of the bent pipe to form an epoxy powder layer; the coating device comprises an extrusion die, the extrusion die is used for extruding an adhesive and polyethylene to form a double-layer pipe with the adhesive on the inner layer and the polyethylene on the outer layer, and the double-layer pipe is coated with an epoxy powder layer; and the cooling device is used for cooling the bent pipe. The conveying device carries the bent pipe to sequentially pass through all the working procedures, 3PE corrosion prevention of the hot-bending bent pipe is completed in a spraying and extrusion coating mode, the automation degree is improved while the corrosion prevention performance is improved, then the corrosion prevention cost is reduced, and the construction efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of hot-bent pipe anti-corrosion, and in particular to a hot-bent pipe 3PE anti-corrosion construction system and method. Background Art

[0002] When constructing long-distance pipelines, the pipelines need to pass through complex paths, so a large number of hot-bent pipes are required. Due to the special-shaped structure of the hot-bent pipes, they cannot be rotated along the axis for anti-corrosion layer winding, so they cannot be subjected to 3PE anti-corrosion in the mechanized extrusion process like straight pipes. The anti-corrosion layer of hot-bent pipes is mainly 2FBE, but its coating thickness, mechanical strength, and electrical insulation performance cannot match the 3PE coating of straight pipes.

[0003] Although there are customized elbow coatings with better protective performance than 2FBE, such as flame-sprayed polyolefins (which fully match the performance of the 3PE anti-corrosion layer on the pipe body) and liquid coatings (especially liquid polyurethane, which has good resistance to impact damage), these coatings are applied manually, have high anti-corrosion costs and low efficiency, and are not suitable for large-scale promotion and application. Summary of the invention

[0004] The purpose of the present invention is to provide a hot-bent pipe 3PE anti-corrosion construction system and method to solve the problems of poor performance of the hot-bent pipe anti-corrosion layer, high anti-corrosion cost and low efficiency.

[0005] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0006] A hot-bent bent pipe 3PE anti-corrosion construction system comprises a conveying device, a heating device, a powder spraying device, a coating device and a cooling device; the conveying device conveys the bent pipe through the heating device, the powder spraying device, the coating device and the cooling device in sequence; the heating device is used to heat the bent pipe, and the powder spraying device sprays epoxy powder on the surface of the bent pipe to form an epoxy powder layer; the coating device comprises an extrusion die, and the extrusion die is used to extrude adhesive and polyethylene to form a double-layer pipe with an inner layer of adhesive and an outer layer of polyethylene, and the double-layer pipe is coated with the epoxy powder layer; the cooling device is used to cool the bent pipe.

[0007] Furthermore, the cooling device includes an air cooling unit and a water cooling unit. The bent pipe first passes through the air cooling unit and then passes through the water cooling unit. The air cooling unit pressurizes the bent pipe to make the double-layer pipe fit with the epoxy powder layer.

[0008] Furthermore, the hot-bent pipe 3PE anti-corrosion construction system also includes a vacuum adsorption device, which is connected to the extrusion die and is used to vacuum the annular space between the double-layer pipe and the epoxy powder layer; the extrusion die is arranged as an annular structure, and an annular extrusion port is arranged at one end of the annular structure for extruding the double-layer pipe, and the other end is connected to the vacuum adsorption device.

[0009] Furthermore, the coating device also includes two adjustable telescopic rods arranged along the axis direction of the extrusion die, the output ends of the two adjustable telescopic rods are hinged to the extrusion die, and the adjustable telescopic rods are extended and retracted to adjust the angle and position of the extrusion die.

[0010] Furthermore, the coating device also includes a mold hanger, which suspends the extrusion mold in a height-adjustable manner.

[0011] Furthermore, the coating device also includes an adhesive extruder and a polyethylene extruder, and the adhesive extruder and the polyethylene extruder are respectively connected to the extrusion die.

[0012] Furthermore, the coating device also includes a first melt metering pump and a second melt metering pump, the first melt metering pump is used to connect the extrusion die and the adhesive extruder, and the second melt metering pump is used to connect the extrusion die and the polyethylene extruder.

[0013] Furthermore, the coating device also includes a heating ring, which is inserted into the extrusion die and is used to heat the extrusion die.

[0014] Another aspect of the present invention provides a method for hot-bent pipe 3PE anti-corrosion construction, using the above-mentioned hot-bent pipe 3PE anti-corrosion construction system, comprising the following steps:

[0015] Bend heating: The heating device heats the bend;

[0016] Powder spraying: The powder spraying device sprays epoxy powder on the surface of the elbow to form an epoxy powder layer;

[0017] Extrusion coating: The extrusion die extrude adhesive and polyethylene to form a double-layer tube with an inner layer of adhesive and an outer layer of polyethylene, and the double-layer tube is coated with an epoxy powder layer;

[0018] Cooling: The cooling device cools the bent pipe.

[0019] Furthermore, in the extrusion coating step, a vacuum is drawn between the double-layer tube and the epoxy powder layer so that the double-layer tube is closely attached to the epoxy powder layer.

[0020] Based on the above technical solutions, the technical effects that can be achieved by the present invention are:

[0021] The hot-bent bent pipe 3PE anti-corrosion construction system provided by the present invention comprises a conveying device, a heating device, a powder spraying device, a coating device and a cooling device; the conveying device conveys the bent pipe through the heating device, the powder spraying device, the coating device and the cooling device in sequence; the heating device is used to heat the bent pipe, and the powder spraying device sprays epoxy powder on the surface of the bent pipe to form an epoxy powder layer; the coating device comprises an extrusion die, and the extrusion die is used to extrude adhesive and polyethylene to form a double-layer pipe with an inner layer of adhesive and an outer layer of polyethylene, and the double-layer pipe is coated with the epoxy powder layer; the cooling device is used to cool the bent pipe.

[0022] The hot-bent pipe 3PE anti-corrosion construction system provided by the present invention carries the bent pipe through a heating device, a powder spraying device, a coating device and a cooling device in sequence through a conveying device, and completes the 3PE anti-corrosion of the hot-bent pipe by spraying and extrusion coating, thereby improving the anti-corrosion performance of the hot-bent pipe and at the same time improving the degree of automation, thereby reducing the anti-corrosion cost and improving construction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 A schematic diagram of the structure of a 3PE anti-corrosion construction system for hot-bent pipes provided in an embodiment of the present invention;

[0025] Figure 2 It is a partial structural schematic diagram of the coating device;

[0026] Figure 3 is a schematic diagram of another part of the structure of the coating device;

[0027] Figure 4 Schematic diagram of the structure of the vacuum device.

[0028] Icons: 200-heating device; 300-powder spraying device; 500-vacuum adsorption device; 110-transmission roller; 120-traction unit; 410-extrusion mold; 420-adjustable telescopic rod; 430-mold hanger; 440-adhesive extruder; 450-polyethylene extruder; 460-first melt metering pump; 470-second melt metering pump; 480-melt diverter; 490-feeding pipe. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0032] The anti-corrosion layer of hot-bent pipes is mainly 2FBE, but its anti-corrosion performance is poor, and the manual coating method has the problems of high cost and low efficiency.

[0033] In view of this, the present invention provides a hot-bent bent pipe 3PE anti-corrosion construction system, including a conveying device, a heating device 200, a powder spraying device 300, a coating device and a cooling device; the conveying device conveys the bent pipe through the heating device 200, the powder spraying device 300, the coating device and the cooling device in sequence; the heating device 200 is used to heat the bent pipe, and the powder spraying device 300 sprays epoxy powder on the surface of the bent pipe to form an epoxy powder layer; the coating device includes an extrusion die 410, and the extrusion die 410 is used to extrude adhesive and polyethylene to form a double-layer pipe with an inner layer of adhesive and an outer layer of polyethylene, and the double-layer pipe is coated with an epoxy powder layer; the cooling device is used to cool the bent pipe.

[0034] The hot-bent pipe 3PE anti-corrosion construction system provided by the present invention carries the bent pipe through a heating device 200, a powder spraying device 300, a coating device and a cooling device in sequence through a conveying device, and completes the 3PE anti-corrosion of the hot-bent pipe by spraying and extrusion coating, thereby improving the anti-corrosion performance of the hot-bent pipe and at the same time improving the degree of automation, thereby reducing the anti-corrosion cost and improving construction efficiency.

[0035] The following combination Figure 1-Figure 4 The structure and shape of the hot-bent pipe 3PE anti-corrosion construction system provided in this embodiment are described in detail:

[0036] The hot-bent pipe 3PE anti-corrosion construction system provided in this embodiment includes a conveying device, a heating device 200, a powder spraying device 300, a coating device, a vacuum adsorption device 500, a cooling device and a hoisting device, which is used to perform three-layer polyethylene anti-corrosion on the hot-bent pipe, namely, a bottom layer of epoxy powder, a middle layer of adhesive, and an outer layer of polyethylene, such as Figure 1 The hoisting device is used to hoist the bent pipe to be processed to the conveying device and to hoist the processed bent pipe from the conveying device, that is, to hoist the pipe online and offline.

[0037] In this embodiment, the conveying device includes a conveying roller 110 and a traction unit 120. The conveying roller 110 is an annular channel, and a plurality of transmission rollers are arranged along the circumference to form an arc-shaped structure to adapt to the curved pipe. The axis of the transmission roller extends radially along the annular channel. The traction unit 120 includes a rotating motor, a connecting arm and a tooling block. One end of the connecting arm is connected to the rotating motor, and the other end is connected to the tooling block. The rotating motor is concentric with the annular channel and is used to drive the connecting arm to rotate. The tooling block is inserted into the inner wall of the curved pipe and abuts against the curved pipe to push the curved pipe to move along the annular channel to enter each process. In order to ensure stable conveying of the curved pipe and forward and reverse conveying, two connecting arms and corresponding tooling blocks can be set, and the two tooling blocks are respectively inserted into the two ends of the curved pipe. When conveying the curved pipe, the angle between the two connecting arms is adjusted according to the length of the curved pipe, and the tooling block and the curved pipe are pushed to move along the transmission pipeline by the rotation of the rotating motor.

[0038] In order to improve adaptability and enable the tooling block to be reliably connected to the bent pipe, the tooling block can be set as an arc-shaped pipe, and a top screw can be set circumferentially on the pipe wall. The top screw is threadedly connected to the pipe wall, and the top screw can be made to abut against the inner wall of the bent pipe by adjusting the position of the top screw.

[0039] In this embodiment, a heating device 200, a powder spraying device 300, a coating device, a vacuum adsorption device 500 and a cooling device are sequentially arranged along the conveying direction of the bent pipe. The heating device 200 uses a medium frequency heating coil to perform medium frequency heating on the bent pipe; the powder spraying device 300 is an annular body, and the bent pipe passes through the annular body for epoxy powder spraying. Epoxy powder spray guns are evenly arranged along the inner wall of the annular body to ensure uniform and comprehensive spraying of the bent pipe.

[0040] The cooling device includes an air cooling unit and a water cooling unit. The elbow first passes through the air cooling unit and then the water cooling unit. The air cooling unit is set as an annular structure, and multiple nozzles are set on the inner wall for blowing air to the surface of the elbow. The temperature is lowered by blowing air and the double-layer pipe is evenly attached to the epoxy powder layer by wind pressure. The water cooling unit can cool the anti-corrosion layer to below 60°C by spraying, soaking, etc., so that the anti-corrosion layer has good mechanical properties. The elbow passes through the annular structure of the air cooling unit, and the wind pressure is used to pressurize the elbow to make the double-layer pipe fit the epoxy powder layer.

[0041] In this embodiment, the coating device includes an extrusion die 410, an adjustable telescopic rod 420, a die hanger 430, an adhesive extruder 440, a polyethylene extruder 450, a first melt metering pump 460, a second melt metering pump 470 and a melt splitter 480, such as Figure 1-Figure 4 As shown. The melt splitter 480 is connected to the adhesive extruder 440 and the polyethylene extruder 450, and is used to perform constant pressure splitting of the adhesive and polyethylene output by the adhesive extruder 440 and the polyethylene extruder 450, so that the high-temperature melt enters the feed pipe 490 evenly, and the pressure and flow rate of each stream of material extrusion can be adjusted and balanced separately; the first melt metering pump 460 and the second melt metering pump 470 are connected to the melt splitter 480, and are used to quantitatively convey the adhesive and polyethylene into the extrusion die 410, respectively, that is, the first melt metering pump 460 is connected to the adhesive extruder 440, and the second melt metering pump 470 is connected to the polyethylene extruder 450. The melt metering pump can quantitatively and forcibly control the flow rate and pressure of the melt, so that the material flow entering the die is stable and constant.

[0042] The extrusion die 410 is connected to the first melt metering pump 460 and the second melt metering pump 470 through the feed pipe 490, respectively, to extrude the adhesive and polyethylene and form a tubular pipe, that is, a double-layer pipe with an inner layer of adhesive and an outer layer of polyethylene. The die hanger 430 suspends the extrusion die 410 in a height-adjustable manner, so that the extrusion die 410 can adapt to elbows of different specifications. Specifically, a wire rope winch method can be adopted, or it can be adjusted by a screw, that is, two wire ropes are connected to the screw and the screw sleeve respectively, and the screw length is adjusted by rotating the screw to change the suspension height. Two adjustable telescopic rods 420 are arranged along the axis direction of the extrusion die 410 and the output end is hinged to the extrusion die 410. The telescopic direction of the adjustable telescopic rod 420 is the radial direction of the extrusion die 410, so that the angle and position of the extrusion die 410 can be adjusted to adapt to the elbow by adjusting the telescopic rod 420. At this time, the flexible connection of the suspension mode can be adjusted in conjunction with the telescopic rod 420 to avoid being unable to adjust the extrusion die 410 due to excessive constraints.

[0043] The feed pipe 490 uses a high-pressure heating type melt conveying hose with a diameter of 25mm, which can withstand a pressure of up to 10Mp. Each feed pipe 490 is equipped with a heating belt and a digital PID temperature controller for individual control. The hose can withstand a temperature of up to 220 degrees Celsius. By adjusting the coordination of the telescopic rod 420, the mold hanger 430 and the feed pipe 490, the extrusion mold 410 can be adapted to different specifications of elbows and the position and angle changes of the elbows when passing through the extrusion mold 410, so that the center of the extrusion mold 410 is always aligned with the center of the elbow, that is, the curvature changes of the elbows can be adapted.

[0044] In addition, a lifting platform may be provided, and the telescopic rod 420 may be installed on the lifting platform to adjust the height of the telescopic rod 420 and improve adaptability.

[0045] In this embodiment, the extrusion die 410 is set as an annular structure, which is made of 42 chromium-molybdenum steel by forging. One end of the annular structure is provided with an annular extrusion port for extruding a double-layer tube, and the other end is connected to the vacuum adsorption device 500. During operation, the vacuum adsorption device 500 evacuates the annular space between the double-layer tube and the epoxy powder layer, and uses the air pressure difference to make the two fit together. Among them, the extrusion die 410 is provided with an adhesive flow channel and a polyethylene flow channel, and the two converge at the annular extrusion port to ensure the extrusion of the double-layer tube and avoid mixing of the adhesive and polyethylene. Both the adhesive flow channel and the polyethylene flow channel adopt a diversion structure to ensure uniform extrusion of the tubular structure, and the surface of the flow channel is hard chrome plated and polished.

[0046] Due to the effect of gravity, when the double-layer tube formed by the adhesive and polyethylene is coated with the epoxy powder layer, the part located above the bent tube is easy to fit, while a gap is easy to form in the lower part. The wind pressure of the air cooling unit can assist the vacuum suction effect of the vacuum adsorption device 500, so that the double-layer tube and the epoxy powder layer are fully and evenly fitted, eliminating the adverse effects of gravity and ensuring the coating quality.

[0047] In order to prevent the temperature from decreasing during the material conveying and extrusion process, a heating ring is provided inside the extrusion die 410 to heat the extrusion die 410 to ensure uniform and smooth material flow. The heating ring can be surrounded by electric heating wire.

[0048] In this embodiment, the lifting device can be a cantilever crane, a gantry crane, a traveling crane or other structures, which are used to lift the bent pipes. At the same time, multiple bent pipes can be processed at one time, that is, adjacent bent pipes are connected by tooling blocks, and the two ends of the tooling blocks are respectively inserted into the inner wall of the bent pipes to connect the adjacent bent pipes into a whole, which is convenient for the traction unit 120 to drive.

[0049] The working process of the hot-bent pipe 3PE anti-corrosion construction system provided in this embodiment is as follows:

[0050] The lifting device lifts the bent pipe onto the production line, and the two tooling blocks of the traction unit 120 respectively abut the two ends of the bent pipe, and then the rotating motor of the traction unit 120 drives the connecting arm to rotate, thereby driving the tooling blocks to move the bent pipe along the transmission roller 110. The bent pipe first arrives at the heating device 200 for heating, and then arrives at the powder spraying device 300 to spray epoxy powder to form an epoxy powder layer, and then arrives at the extrusion die 410 and penetrates into the double-layer tube extruded by the extrusion die 410. The vacuum adsorption device 500 then evacuates the double-layer tube and the epoxy powder layer so that the double-layer tube is coated on the bent pipe, completing the extrusion coating process. The bent pipe then arrives at the cooling device, and firstly is preliminarily cooled by the air cooling unit and the double-layer tube is evenly attached to the epoxy powder layer by wind pressure, and then further cooled by the water cooling unit to improve the mechanical properties of the anti-corrosion layer. Finally, the traction unit 120 moves the bent pipe to the lifting device and is lifted off the production line by the lifting device.

[0051] Based on the hot-bent pipe 3PE anti-corrosion construction system provided in this embodiment, a hot-bent pipe 3PE anti-corrosion construction method is proposed, comprising the following steps:

[0052] Hoisting and putting on line: The hoisting device lifts the derusted bent pipe and puts the bent pipe on the conveying device for fixation. Then the conveying device transports the bent pipe to each workstation in turn.

[0053] Bend heating: The heating device 200 performs medium frequency heating on the bend.

[0054] Spraying powder: The powder spraying device 300 sprays epoxy powder on the surface of the elbow to form an epoxy powder layer.

[0055] Extrusion coating: the extrusion die 410 extrude adhesive and polyethylene to form a double-layer tube with an inner layer of adhesive and an outer layer of polyethylene, and the double-layer tube is coated with an epoxy powder layer; then the vacuum adsorption device 500 draws a vacuum between the double-layer tube and the epoxy powder layer to make the double-layer tube close to the epoxy powder layer.

[0056] Cooling: The cooling device cools the bent pipe by air and water in turn.

[0057] Lifting off-line: The conveying device conveys the bent pipe to the off-line position, and the lifting device lifts the bent pipe out of the conveying device.

[0058] The hot-bending pipe bending 3PE anti-corrosion construction system provided in this embodiment is mainly used for pipe bending with a diameter between 457mm and 813mm, and the curvature radius of the pipe bending is between 5 and 6 times the pipe diameter. Accordingly, by adjusting the diameter of the annular channel of the transmission roller 110, changing the diameter, thickness and related construction parameters of the extrusion die 410, it can be applied to the anti-corrosion construction of pipe bending of other specifications.

[0059] The hot-bent pipe bending 3PE anti-corrosion construction system provided in this embodiment can realize assembly line operation, replacing manual operation, which can significantly improve production efficiency and production quality, reduce raw material loss, and reduce manual operation risks. The annular conveying device can effectively reduce the construction site area, so that the performance of the anti-corrosion layer of the bent pipe and the anti-corrosion layer of the straight pipe can be well matched, thereby improving the overall anti-corrosion effectiveness of the long-distance pipeline and eliminating the decline in the overall pipeline anti-corrosion performance due to insufficient anti-corrosion performance of the bent pipe.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A hot-bent pipe 3PE anti-corrosion construction system, characterized in that: It comprises a conveying device, a heating device (200), a powder spraying device (300), a coating device and a cooling device; The conveying device conveys the bent pipe to sequentially pass through the heating device (200), the powder spraying device (300), the coating device and the cooling device; The heating device (200) is used to heat the bent pipe, and the powder spraying device (300) sprays epoxy powder on the surface of the bent pipe to form an epoxy powder layer; The coating device comprises an extrusion die (410), wherein the extrusion die (410) is used to extrude adhesive and polyethylene to form a double-layer tube with an inner layer of adhesive and an outer layer of polyethylene, wherein the double-layer tube coats the epoxy powder layer; The cooling device is used to cool the bent pipe.

2. The hot-bent pipe 3PE anti-corrosion construction system according to claim 1 is characterized in that: The cooling device comprises an air cooling unit and a water cooling unit. The bent pipe first passes through the air cooling unit and then passes through the water cooling unit. The air cooling unit pressurizes the bent pipe to make the double-layer pipe fit the epoxy powder layer.

3. The hot-bent pipe 3PE anti-corrosion construction system according to claim 1 is characterized in that: It also includes a vacuum adsorption device (500), which is connected to the extrusion die (410) and is used to evacuate the annular space between the double-layer tube and the epoxy powder layer; The extrusion die (410) is configured as an annular structure, one end of the annular structure is provided with an annular extrusion port for extruding the double-layer tube, and the other end is connected to the vacuum adsorption device (500).

4. The hot-bent pipe 3PE anti-corrosion construction system according to claim 3 is characterized in that: The coating device further comprises two adjustable telescopic rods (420) arranged along the axial direction of the extrusion die (410), the output ends of the two adjustable telescopic rods (420) being hinged to the extrusion die (410), and the adjustable telescopic rods (420) are telescoped to adjust the angle and position of the extrusion die (410).

5. The hot-bent pipe 3PE anti-corrosion construction system according to claim 4 is characterized in that: The coating device further comprises a die hanger (430), wherein the die hanger (430) suspends the extrusion die (410) in a height-adjustable manner.

6. The hot-bent pipe 3PE anti-corrosion construction system according to claim 5 is characterized in that: The coating device further comprises an adhesive extruder (440) and a polyethylene extruder (450), and the adhesive extruder (440) and the polyethylene extruder (450) are respectively connected to the extrusion die (410).

7. The hot-bent pipe 3PE anti-corrosion construction system according to claim 6 is characterized in that: The coating device also includes a first melt metering pump (460) and a second melt metering pump (470), wherein the first melt metering pump (460) is used to connect the extrusion die (410) and the adhesive extruder (440), and the second melt metering pump (470) is used to connect the extrusion die (410) and the polyethylene extruder (450).

8. The hot-bent pipe 3PE anti-corrosion construction system according to claim 3 is characterized in that: The coating device further comprises a heating coil, which is inserted into the extrusion die (410) and is used to heat the extrusion die (410).

9. A hot-bent pipe 3PE anti-corrosion construction method, using the hot-bent pipe 3PE anti-corrosion construction system according to any one of claims 1 to 8, characterized in that: The steps include: Bend heating: the heating device (200) heats the bend; Spraying powder: the powder spraying device (300) sprays epoxy powder on the surface of the elbow to form an epoxy powder layer; Extrusion coating: the extrusion die (410) extrude adhesive and polyethylene to form a double-layer tube with an inner layer of adhesive and an outer layer of polyethylene, and the double-layer tube coats the epoxy powder layer; Cooling: The cooling device cools the bent pipe.

10. The hot-bent pipe 3PE anticorrosion construction method according to claim 9 is characterized in that: In the extrusion coating step, a vacuum is drawn between the double-layer tube and the epoxy powder layer so that the double-layer tube is closely attached to the epoxy powder layer.

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