A kind of anticorrosion technology of prefabricated pipe and conveying pipeline

Abstract

The present invention discloses an anti-corrosion process for a prefabricated pipe and a conveying pipeline, and relates to the technical field of pipeline anti-corrosion. The conveying pipeline includes multiple sections of prefabricated pipes, and adjacent prefabricated pipes are butt-jointed at the open ends of the prefabricated pipes. When the welding position is a dead end, the multiple sections of prefabricated pipes include prefabricated pipes provided with a surfacing area, and adjacent prefabricated pipes are butt-jointed at their respective surfacing areas; the on-site construction steps at the dead end position include: step 600: on-site welding is performed in the surfacing area of ​​adjacent prefabricated pipes; the welding material is consistent with or has similar characteristics to the welding material in the surfacing area, has good weldability with the base material in the surfacing area, and has anti-corrosion characteristics; step 700: non-destructive testing of the weld. The anti-corrosion process for the prefabricated pipe and the conveying pipeline of the present invention solves the technical problem that it is difficult to achieve complete and effective anti-corrosion of the conveying pipeline in the prior art, and has the advantage of high reliability of internal anti-corrosion operations.

Description

Technical Field

[0001] The invention relates to the technical field of pipeline anti-corrosion, and in particular to an anti-corrosion process for a conveying pipeline. Background Art

[0002] Pipelines are used to transport and store media. Common pipelines include long-distance pipelines, inter-field pipelines, and process pipelines. When the medium is corrosive, the pipeline wall thickness will be reduced, and in severe cases, stress corrosion cracking will occur. Therefore, the anti-corrosion quality of the pipeline directly affects its service life.

[0003] At present, there are the following problems in the laying and construction of transportation pipelines: long-distance pipelines are characterized by long mileage and many welds, process pipelines and inter-field pipelines are characterized by many pipe fittings and many bending avoidance structures. The above-mentioned transportation pipelines need to be constructed in sections during laying. After the adjacent pipe fittings are welded, the internal anti-corrosion is sprayed on the inside of the pipeline as a whole. Among them, the internal anti-corrosion of the weld is the weak link in the quality control of corrosion inside the entire pipeline. Summary of the invention

[0004] The purpose of the present invention is to provide an anti-corrosion process for a prefabricated pipe and a conveying pipeline, so as to solve the technical problem that the quality of anti-corrosion in the conveying pipeline is difficult to control.

[0005] To achieve this purpose, on the one hand, a prefabricated pipe is provided, wherein the inner wall of the prefabricated pipe is provided with a reserved area, the reserved area is located at the open end of the prefabricated pipe, and extends from the open end to the inside of the prefabricated pipe, and the reserved area is a bare pipe; an inner coating area adjacent to the reserved area, the coating of the inner coating area is used for corrosion protection inside the pipeline; at the welding temperature of the prefabricated pipe, the temperature at the junction of the reserved area and the inner coating area is lower than the glass transition temperature of the coating material.

[0006] On the other hand, a prefabricated pipe is provided, wherein the inner wall of the prefabricated pipe is provided with a surfacing zone, the surfacing zone is located at the open end of the prefabricated pipe and extends from the open end to the inside of the prefabricated pipe; an inner coating zone is adjacent to or overlapped with the surfacing zone, and the coating of the inner coating zone is used for corrosion protection inside the pipeline; when the prefabricated pipe is subjected to welding heat treatment temperature, the temperature at the position where the surfacing zone and the inner coating zone are adjacent to or overlapped is lower than the glass transition temperature of the coating.

[0007] Further, the surfacing area includes a first finely processed portion, the first finely processed portion includes a slope, and the inner coating area overlaps the slope.

[0008] Furthermore, the surfacing area also includes a rough-machined portion, which is adjacent to the first fine-machined portion, and the rough-machined portion is located at an end of the first fine-machined portion away from the inner coating area; when the prefabricated pipe is under the welding heat treatment temperature, the temperature at the junction of the rough-machined portion and the first fine-machined portion is lower than the glass transition temperature of the coating.

[0009] Furthermore, the surfacing area further includes a second fine-machined portion, the second fine-machined portion is located at the opening end, and the second fine-machined portion is rounded.

[0010] Furthermore, the slope has a gradient of 7° to 8°.

[0011] Furthermore, the inner wall of the prefabricated pipe is provided with a surfacing area, which is located at the open end of the prefabricated pipe and extends from the open end to the inside of the prefabricated pipe; an inner coating area is adjacent to or overlapped with the surfacing area, and the coating of the inner coating area is used for corrosion protection inside the pipeline; when the prefabricated pipe is under the welding heat treatment temperature, the temperature at the position where the surfacing area is adjacent to or overlapped with the inner coating area is lower than the glass transition temperature of the coating.

[0012] Furthermore, both ends of the prefabricated tube are open ends, and both ends of the prefabricated tube are provided with the reserved area.

[0013] On the other hand, an anti-corrosion process for a conveying pipeline is provided. When the construction location is near a dead end, the prefabricated pipe according to claim 2 is used, and the steps of on-site construction include: step 600: performing on-site welding in the surfacing area of ​​adjacent prefabricated pipes, and the welding material is consistent with the welding material in the surfacing area or has similar characteristics; step 700: performing non-destructive testing on the weld.

[0014] On the other hand, an anti-corrosion process for a conveying pipeline is provided, characterized in that the prefabricated pipe described in claim 1 is used, and the steps of on-site construction include: step 100: pre-sandblasting the reserved area of ​​the prefabricated pipe; step 200: welding adjacent prefabricated pipes on-site in their respective reserved areas; step 300: using a three-dimensional detection robot to detect the appearance of the weld; step 400: before the conveying pipeline is welded to the dead end position, a patching robot enters from the open end of the conveying pipeline into the interior of the currently welded conveying pipeline, sandblasts the inner weld area first and then patches it, and after the inner weld is patched, the patching robot exits from the open end; step 500: after the coating at the patched position is cured, a coating detection robot enters from the open end into the interior of the currently welded conveying pipeline, and detects the quality and / or thickness of the coating applied by the patching robot in step 400.

[0015] One of the above technical solutions has the following advantages or beneficial effects: This solution provides a prefabricated pipe, one of the open ends of which has a reserved area for on-site welding. After welding, the weld and the reserved areas on both sides of the weld are subjected to internal anti-corrosion operations by a patching robot. An internal coating area is prefabricated inside, and there is no need to perform internal anti-corrosion operations again during the on-site laying of the pipeline. This prefabricated pipe is more suitable for occasions where existing patching robots can enter. Compared with the existing technology, it has the advantages of less on-site patching operations and a high degree of automation.

[0016] This solution provides another prefabricated pipe, one of the open ends of which has a surfacing area, which is made by surfacing technology, and the surfacing technology is corrosion-resistant surfacing. When two prefabricated pipes are welded at the open end, the weld here already has anti-corrosion performance. Compared with the existing technology, after the two prefabricated pipes are welded on site, there is no need to perform anti-corrosion work in the patching. It is especially suitable for areas where it is inconvenient to operate the patching work on the site of the pipeline, such as bends and dead ends of the pipeline that the patching robot cannot enter.

[0017] This solution provides an anti-corrosion process for conveying pipelines. When encountering a dead end in the pipeline and the turning radius of the elbow is smaller than the minimum operating angle of the patching robot, a prefabricated pipe with a surfacing area is used for connection, and no internal anti-corrosion work is required after welding. Prefabricated pipes with a reserved area are used for connection in other locations, and a patching robot is used for on-site patching after welding. Therefore, the internal anti-corrosion of the conveying pipeline connected by the anti-corrosion process for conveying pipelines provided by this solution has no weak points and is of controllable quality. Manual internal anti-corrosion work is no longer required during on-site construction, avoiding all problems caused by manual internal anti-corrosion work, and having the advantage of high reliability in on-site construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a cross-sectional view of a prefabricated tube in an embodiment; Figure 2 is a cross-sectional view of another prefabricated tube in the embodiment; Figure 3 yes Figure 2 A partial enlarged view of point I in the middle; Figure 4 is a cross-sectional view of another prefabricated tube in the embodiment; Figure 5 Schematic diagram of the anti-corrosion process construction of the conveying pipeline in the embodiment; Figure 6 is a schematic diagram of the anti-corrosion process welding of the conveying pipeline in the embodiment; Figure 7 It is a schematic diagram of a patching robot in an anti-corrosion process of a conveying pipeline in an embodiment.

[0019] In the figure: 1-inner coating area; 2-reserved area; 3-surfacing area; 31-first fine processing part; 32-rough processing part; 33-second fine processing part; 4-filling robot. DETAILED DESCRIPTION

[0020] In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0021] The pipeline has the characteristics of long mileage and many curved avoidance parts. It needs to be constructed in sections during laying. The adjacent pipe fittings are welded, and the internal corrosion protection of the weld is the weak link in the quality control of the corrosion in the entire pipeline. At present, the recognized construction difficulty is the quality of the weld patching construction, especially the patching operation at the dead end, which has high requirements for the operation of on-site construction. The dead end refers to the last welding position between two adjacent pipe fittings in the pipeline. Compared with the normal welding weld, it is difficult to align the pipe ends when assembling the dead end, and the dead end cannot be moved freely front, back, left, and right. After the welding of the dead end position is completed, the internal weld patching operation is required. The internal weld patching refers to the coating of the pipeline connection area. The pipeline patching is performed on site after the on-site welding is completed. Restricted by the working environment and construction conditions, the quality of the patching anti-corrosion layer is greatly affected by uncertain factors, especially when the patching position is a "dead end", its internal corrosion protection quality is the weak link in the quality control of the corrosion in the entire pipeline.

[0022] In order to ensure the quality of internal anti-corrosion, patching robots are currently used for patching. However, due to the influence of its turning radius and construction sequence, if the turning radius of the conveying pipeline is smaller than that of the patching robot, the patching robot cannot enter. These positions are also the dead ends of the conveying pipeline. These dead ends cannot be operated by patching robots, but can only be operated manually. This will not only greatly increase the construction time of the conveying pipeline, but also there is a risk of suffocation when working manually in the conveying pipeline, and the sandblasting cannot guarantee the quality and cannot be effectively recycled, and the coating quality is also difficult to control. In addition, manual operation also has the problem of high construction costs.

[0023] In the prior art, when encountering the above-mentioned dead-end position with a small turning radius, the pipeline is extended to avoid the position with a small turning radius in the conveying pipeline. However, this will inevitably greatly increase the design and construction length of the conveying pipeline. In particular, the conveying pipeline usually adopts special steel. Extending the design and construction length of the conveying pipeline will inevitably greatly increase the cost.

[0024] Figure 1-Figure 4Three types of prefabricated pipes of this embodiment are shown. The preferred material of the prefabricated pipes is steel pipes. The prefabricated pipes can be straight pipes, curved pipes or elbows. The prefabricated pipes are assembled and inspected in the factory. The use of prefabricated pipes in the delivery pipeline can reduce the time of on-site construction, improve work efficiency, shorten the construction period, and improve the controllability of the delivery pipeline quality control.

[0025] Figure 1 The first prefabricated pipe of this embodiment is shown, and the inner wall of the prefabricated pipe has an inner coating 1 in the middle and a reserved area 2 at both ends. The reserved area 2 is located at the open end of the prefabricated pipe and extends from the open end to the inside of the prefabricated pipe. The reserved area 2 is a bare pipe. The inner coating area 1 is adjacent to the reserved area 2. The coating material sprayed on the inner coating area 1 is used for corrosion protection inside the pipeline. The inner coating area 1 preferably uses a post-curing FBE powder with a primer. The inner coating area of ​​the prefabricated pipe can be processed in advance in the factory and then transported to the site. When laying the conveying pipeline, multiple sections of this type of prefabricated pipe are connected in pairs by welding at the reserved area 2. The length of the reserved area 2 depends on the temperature at the junction of the reserved area and the inner coating area of ​​the prefabricated pipe at the welding temperature, that is, the temperature at the junction of the reserved area 2 and the inner coating area 1 during welding is less than the glass transition temperature of the coating material of the inner coating area 1. Since the length of the reserved area is designed taking the above temperature into account, the performance of the coating material of the inner coating area 1 is not affected after the welding is completed. After the above-mentioned prefabricated pipes are welded in pairs, the anti-corrosion construction of the weld and the reserved area 2 around it can be completed by a patching robot used for the internal coating of the pipeline girth weld.

[0026] In summary, if Figure 1 As shown, both ends of the first prefabricated pipe provided in this embodiment have a reserved area 2, and the middle of the two reserved areas 2 is an inner coating area 1. The inner coating area 1 of the prefabricated pipe is prefabricated in the factory, and the reserved area 2 of the prefabricated pipe is used for on-site welding. After welding, the weld and the reserved areas on both sides thereof are subjected to internal anti-corrosion operations by a patching robot, and the inner coating area inside the pipeline is prefabricated with an anti-corrosion layer, and there is no need to spray the inner anti-corrosion again on site. The first prefabricated pipe is more suitable for occasions where the existing patching robot can enter, and compared with the prior art, it has the advantage of less on-site patching operations.

[0027] Figure 2The second prefabricated pipe of the present embodiment is shown, and an inner coating area 1 is provided in the middle of the inner wall, a reserved area 2 is provided at one port, and a surfacing area 3 is provided at the other open end. The reserved area 2 is the same as the reserved area of ​​the first prefabricated pipe. The surfacing area 3 is made by a surfacing process, and the surfacing process is corrosion-resistant surfacing. Since the surfacing area 3 is made by corrosion-resistant surfacing, when the prefabricated pipes are welded at the open ends, when the open ends of the prefabricated pipes on both sides are both surfacing areas 3, then the welds here have anti-corrosion properties after being processed by the welding connection process. At the construction site of a long-distance pipeline, if both sides of the butt joint are surfacing areas, then after welding, the weld and the surfacing areas near it have anti-corrosion properties, and the inner coating area 1 also has anti-corrosion properties, and the above-mentioned pipelines after docking do not need to be subjected to anti-corrosion operations such as patching.

[0028] Figure 4 The third prefabricated pipe of the present embodiment is shown, in which an inner coating area 1 is arranged in the middle of the inner wall, and surfacing areas 3 are arranged at the open ends on both sides. Then, all the internal anti-corrosion of the prefabricated pipe is processed in advance in the factory and then transported to the site. No internal anti-corrosion operation is required after on-site welding.

[0029] like Figure 3As shown, a prefabricated pipe includes a surfacing area 3, and the surfacing area 3 further includes a first fine processing part 31, a rough processing part 32, and a second fine processing part 33. The first fine processing part 31 includes a slope, and the inner coating area 1 is superimposed on the first fine processing part 31. The prefabricated pipe first processes the surfacing area 3, and then processes the first fine processing part 31 at the end of the surfacing area 3 away from the open end. The first fine processing part 31 is used to overlap the inner coating area 1, so that the inner coating area 1 and the surfacing area 3 can have a smooth transition. Otherwise, there will be a step between the end of the surfacing area 3 located away from the open end of the prefabricated pipe and the inner wall of the prefabricated pipe. At this time, the inner coating area 1 is prone to uneven thickness and missing coating when processing, resulting in weak anti-corrosion points on the inner wall of the prefabricated pipe. At this time, the temperature at the intersection of the rough processing part 32 and the first fine processing part 31 is lower than the glass transition temperature of the inner coating. Since the first fine processing part is used to overlap the inner coating area 1, the rough processing part of the above size leaves enough heat-affected zone to prevent the temperature rise during welding of the surfacing area 3 from affecting the performance of the inner coating area 1. Furthermore, the first fine-machined portion 31 includes a slope, and the slope surface has a slope of 7° to 8°. This angle can ensure that the inner coating area 1 is evenly covered on the first fine-machined portion 31 of the surfacing area 3. The second fine-machined portion 33 is located at the open end of the prefabricated pipe, and the second fine-machined portion 33 is rounded to calibrate the non-roundness of the pipe end while ensuring the effective thickness of the surfacing. The rounding of the second fine-machined portion 33 can be performed by turning, such as boring. When the above-mentioned prefabricated pipe is processed in the factory, the surfacing area 3 is first processed, and then the inner coating area 1 is processed. When processing the surfacing area 3, the first fine-machined portion 31 with a slope shape is first processed, and then the slope surface should be anchored before coating. The inner coating area 1 is processed on the first fine-machined portion 31 after anchoring. Anchoring the slope surface of the first fine-machined portion 31 can ensure that the inner coating has greater adhesion.

[0030] In summary, if Figure 1 In this embodiment, the prefabricated pipes with reserved areas 2 at both ends are used for long straight pipe sections or curved pipes with large turning radius on the conveying pipeline. After welding two by two, the patching robot is used for patching and anti-corrosion operation. Therefore, Figure 1 The length of the prefabricated pipe shown can be increased to the upper limit of pipeline transportation, which can not only reduce the number of welding locations but also improve construction efficiency. Figure 2 and Figure 4 As shown, the prefabricated pipe of this embodiment is provided with a cladding area 3 at one of the opening ends, which is particularly suitable for areas where on-site patching of pipelines is inconvenient to operate. After on-site welding, no internal anti-corrosion operation is required, and it is suitable for bends and dead ends of pipelines that patching robots cannot enter. For example, the bend of the bend on the pipeline is smaller than the turning radius of the patching robot, or there are elbows, and other locations that are difficult for patching robots to enter. Figure 2As shown, a prefabricated pipe with a surfacing area 3 at one open end and a reserved area at the other end is welded to another prefabricated pipe with a reserved area at one end, and welded to another prefabricated pipe with a surfacing area at one end, that is, used to connect pipes with surfacing areas and reserved areas on both sides of the butt joint. It can be seen that the three prefabricated pipes provided in this embodiment can meet any shape design of the conveying pipeline, and the construction of internal anti-corrosion does not require manual work.

[0031] like Figure 5-Figure 7 As shown, this embodiment also provides an anti-corrosion process for a conveying pipeline, wherein the conveying pipeline includes a plurality of sections of prefabricated pipes, and adjacent prefabricated pipes are butt-jointed at the open ends of the prefabricated pipes.

[0032] Before laying the transmission pipeline, the overall direction and prefabricated pipe type should be planned first.

[0033] In large-scale straight sections or curved sections with a turning radius larger than the turning radius of the patching robot, the first type of prefabricated pipe is used, i.e. Figure 1 The prefabricated tube shown has a reserved area 2 at both ends, for example Figure 5 A and B in the figure. The on-site construction steps of the anti-corrosion process of the pipeline here include: Step 100: Pre-sandblast the reserved area 2 of the prefabricated pipe to clean and improve the surface quality of the reserved area material, remove dirt, grease, rust and oxides on the surface of metal and other materials, and improve the surface roughness and adhesion to facilitate subsequent welding and coating of internal anti-corrosion materials.

[0034] Step 200: Adjacent prefabricated pipes are welded on site in their respective reserved areas 2. Figure 5 and Figure 6 shown.

[0035] Step 300: Use a three-dimensional inspection robot to inspect the appearance of the weld; preferably, the excess height and misalignment of the weld should be less than 1 mm or determined according to the thickness of the patch coating.

[0036] Step 400: Before the conveying pipeline is welded to the dead end position, the patching robot 4 enters the interior of the conveying pipeline that has been welded from the open end of the dead end side of the conveying pipeline or other open ends, sandblasts the inner weld area first and then performs patching; after the inner weld patching is completed, the patching robot 4 exits from the open end, such as Figure 7 As shown; Step 500: After the coating at the patching joint is cured, the coating inspection robot enters the interior of the currently welded conveying pipeline from the open end. The coating inspection robot includes spark inspection and thickness inspection. Spark inspection is used to detect the leak point of the internal anti-corrosion, and thickness inspection is used to detect whether the coating has reached the effective thickness. After the thickness inspection is qualified, the welding and internal anti-corrosion construction of the above pipe section is completed.

[0037] During the laying of pipelines, Figure 5 In C, when the butt joint is a dead joint, or one side is a prefabricated pipe with a reserved area, the prefabricated pipe at this location adopts the second type of prefabricated pipe, that is, a structure with a reserved area 2 at one end and a cladding area 3 at the other end. For the prefabricated pipe at this location, the welding process near the reserved area 2 adopts steps 100 to 500. The welding process near the cladding area 3 adopts the following steps 600 to 700.

[0038] During the laying of the pipeline, if the position to be laid is a dead end, or there are elbow pipes on both sides of the position to be laid, or the turning radius of the elbow pipe is smaller than the turning radius of the patching robot 4, or other pipeline positions that are difficult for the patching robot to enter, for example Figure 5 At D and E in the figure, the third type of prefabricated pipe, i.e., a prefabricated pipe with cladding area 3 at both ends, is used to connect the above positions. The on-site construction steps at this position include: Step 600: On-site welding is performed in the cladding area 3 of the adjacent prefabricated pipe. The welding material is consistent with or has similar properties to the welding material of the cladding area 3, has good weldability with the base material of the cladding area 3, and has anti-corrosion properties, such as Figure 6 As shown; Step 700: Perform nondestructive testing on the weld. Preferably, the nondestructive testing adopts phased array testing. After the phased array testing is qualified, the welding and internal anti-corrosion construction of the above pipe section is completed.

[0039] In summary, the anti-corrosion process of the conveying pipeline of this embodiment uses a prefabricated pipe including a surfacing area at the dead end position or the position where the turning radius of the elbow is smaller than the turning radius of the patching robot and the position where the patching robot in the prior art is difficult to enter. The open end of the prefabricated pipe is first surfacing, and the inner coating area is coated before being transported to the site for welding. The welding material is consistent with the welding material of the surfacing area or has similar characteristics, and has good weldability with the base material of the surfacing area, and has anti-corrosion characteristics. After welding, the pipe section at this location has anti-corrosion performance, and there is no need to perform on-site anti-corrosion operations. At other locations of the conveying pipeline, such as large-scale long straight sections and large turning radius, the prefabricated pipe uses the prefabricated pipe with a reserved area provided in Example 1, and is operated by a patching robot after on-site welding. This embodiment also provides a prefabricated pipe connecting the above two sections of the conveying pipeline, that is, one end is a reserved area, the other end is a surfacing area, the reserved area is welded with the reserved area of ​​another prefabricated pipe on the docking side, and the surfacing area is welded with the surfacing area of ​​another prefabricated pipe on the docking side. The weld at the above reserved area is operated by a patching robot.

[0040] Therefore, the internal corrosion protection of the conveying pipeline connected by the combination of three prefabricated pipes and the anti-corrosion process in this embodiment has no weak points and the quality is controllable. Manual internal corrosion protection operations are no longer required during on-site construction, thus avoiding all problems caused by manual internal corrosion protection operations and having the advantage of high reliability in on-site construction.

[0041] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0043] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A prefabricated pipe, characterized in that: The inner wall of the prefabricated pipe is provided with a reserved area, the reserved area is located at the open end of the prefabricated pipe and extends from the open end to the inside of the prefabricated pipe, and the reserved area is a bare pipe; An inner coating area adjacent to the reserved area, wherein the coating of the inner coating area is used for corrosion protection inside the pipeline; When the prefabricated tube is at the welding temperature, the temperature at the junction of the reserved area and the inner coating area is lower than the glass transition temperature of the coating material.

2. A prefabricated pipe, characterized in that: The inner wall of the prefabricated pipe is provided with a surfacing area, the surfacing area is located at the opening end of the prefabricated pipe and extends from the opening end to the inside of the prefabricated pipe; An inner coating area adjacent to or overlapping the cladding area, wherein the coating of the inner coating area is used for corrosion protection inside the pipeline; When the prefabricated pipe is subjected to welding heat treatment temperature, the temperature at the position where the cladding area and the inner coating area are adjacent to or overlapped is lower than the glass transition temperature of the coating.

3. The prefabricated pipe according to claim 2, characterized in that: The weld overlay region includes a first finely machined portion, the first finely machined portion includes a slope, and the inner coating region overlaps the slope.

4. The prefabricated pipe according to claim 3, characterized in that: The surfacing area further includes a rough-machined portion, the rough-machined portion is adjacent to the first fine-machined portion, and the rough-machined portion is located at an end of the first fine-machined portion away from the inner coating area; When the prefabricated pipe is subjected to a welding heat treatment temperature, a temperature at a junction of the rough-machined portion and the first fine-machined portion is lower than a glass transition temperature of the coating.

5. The prefabricated pipe according to claim 2, characterized in that: The surfacing area further includes a second finely processed portion, which is located at the opening end and is rounded.

6. The prefabricated pipe according to claim 3, characterized in that: The slope has a gradient of 7° to 8°.

7. The prefabricated pipe according to claim 1, characterized in that: The inner wall of the prefabricated pipe is provided with a surfacing area, which is located at the open end of the prefabricated pipe and extends from the open end to the inside of the prefabricated pipe; an inner coating area is adjacent to or overlapped with the surfacing area, and the coating of the inner coating area is used for corrosion protection inside the pipeline; when the prefabricated pipe is subjected to welding heat treatment temperature, the temperature at the position where the surfacing area is adjacent to or overlapped with the inner coating area is lower than the glass transition temperature of the coating.

8. The prefabricated pipe according to claim 1, characterized in that: Both ends of the prefabricated tube are open ends, and both ends of the prefabricated tube are provided with the reserved areas.

9. A pipeline anti-corrosion process, characterized in that: When the construction location is near a dead end, the prefabricated pipe according to claim 2 is used, and the steps of on-site construction include: Step 600: Performing on-site welding in the cladding area of ​​adjacent prefabricated pipes, wherein the welding material is consistent with or has similar properties to the welding material in the cladding area; Step 700: Perform nondestructive testing on the weld.

10. A pipeline anti-corrosion process, characterized in that: Using the prefabricated pipe according to claim 1, the steps of on-site construction include: Step 100: Pre-sanding the reserved area of ​​the prefabricated pipe; Step 200: Adjacent prefabricated pipes are welded on site at their respective reserved areas; Step 300: Using a three-dimensional inspection robot to inspect the appearance of the weld; Step 400: before the conveying pipeline is welded to the dead end position, the patching robot enters the interior of the conveying pipeline that has been welded from the open end of the conveying pipeline, sandblasts the inner weld area first and then performs patching. After the inner weld patching is completed, the patching robot exits from the open end; Step 500: After the coating at the patching joint is cured, the coating inspection robot enters the interior of the currently welded conveying pipeline from the open end to inspect the quality and / or thickness of the coating applied by the patching robot in step 400.

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