Large HDPE pipeline joint welding method and pipe body system

Abstract

The invention relates to the technical field of HDPE pipeline welding, in particular to a large HDPE pipeline joint welding method and a pipe body system.The large HDPE pipeline joint welding method comprises the following steps that S1, joints of HDPE pipelines are aligned, a welding strip is connected to an internal supporting device in a sleeving mode, a repair welding area is reserved, and the repair welding area is located between the head end and the tail end of the welding strip; the internal supporting device is moved to the joint of the adjacent HDPE pipeline, and the internal supporting device is adjusted to enable the welding strip to abut against the inner wall of the joint area of the HDPE pipeline; s2, a welding strip is connected with a welding machine, a connector of the HDPE pipeline is subjected to electric fusion welding, and an internal supporting device is removed after welding of the welding strip is completed; according to the welding method, the problem that in the prior art, welding of the inner wall of a large HDPE pipeline connector is not firm is effectively solved, the welding strength, the sealing performance and the reliability are greatly improved, the risk of welding failure is reduced, and the construction efficiency and the applicability are improved.

Description

Technical Field

[0001] The invention relates to the technical field of HDPE pipeline welding, and in particular to a large HDPE pipeline joint welding method and a pipe body system. Background Art

[0002] HDPE pipe is a pipe made of high-density polyethylene (HDPE) with many significant advantages, such as reliable connection, impact resistance, crack resistance, durability and corrosion resistance. For this reason, HDPE pipe has become the mainstream choice in water supply and drainage systems. In general, the overall performance of a pipeline system often depends on its most vulnerable link. For HDPE pipes, this weak point usually occurs at the welded joint. There are currently two main HDPE pipe welding methods used in the industry:

[0003] The first is electric heat fusion socket welding. The specific operation is: first put the special electric fusion pipe fitting on the outside of the pipe, and then use a professional welding machine to energize the pipe fitting. The electric heating wire inside the pipe fitting will melt the contact surface, and after cooling, a firm connection can be formed.

[0004] The second method is hot melt butt welding. This method is to put the end faces of two pipes in contact with a hot plate at the same time, quickly remove the hot plate after the surface melts, and immediately press the two ends together. Maintain a certain pressure until it cools down, and a joint with strength even greater than the pipe itself can be formed.

[0005] However, when welding the joints of large HDPE pipes (with an inner diameter of more than 3 meters and a single section weighing more than 1 ton), due to the large diameter of large HDPE pipes, it is necessary not only to use welding strips for welding on the outside of the pipe joints, but also to weld on the inside of the large HDPE pipe joints. The above two commonly used welding methods cannot meet the requirements of reinforcing the inside of large HDPE pipe joints. Directly applying them to the welding of large HDPE pipe joints will result in loose welding of large HDPE pipes and cause failure of welding of large HDPE pipes. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the existing HDPE pipe welding method that the inside of a large HDPE pipe cannot be reinforced and welded, which easily causes welding failure of the large HDPE pipe, and to provide a large HDPE pipe joint welding method and a pipe body system.

[0007] In a first aspect, the present invention provides a large HDPE pipe joint welding method, comprising the following steps:

[0008] S1. Align the joint of the HDPE pipe, put the welding tape on the internal support device and reserve a repair welding area, which is located between the head end and the tail end of the welding tape; move the internal support device to the joint of the adjacent HDPE pipe, and adjust the internal support device so that the welding tape is pressed against the inner wall of the HDPE pipe joint area;

[0009] S2. Connect the welding strip to the welding machine, perform electric fusion welding on the joint of the HDPE pipe, and remove the internal support device after the welding of the welding strip is completed;

[0010] S3. Perform extrusion welding on the repair welding area.

[0011] The large HDPE pipe joint welding method provided by the present invention uses a welding strip in the internal area of ​​the HDPE pipe joint and uses an internal support device to support and position the welding strip, so that welding reinforcement can be completed in the inner wall area of ​​the pipe joint. Compared with the traditional HDPE pipe welding method, the present method performs reinforcement welding from the inside of the HDPE pipe, which can greatly improve the overall welding strength of the joint and reduce the risk of welding failure.

[0012] The internal support device is used to press the welding strip against the inner wall of the joint area from the inside of the HDPE pipe, which solves the problem of loose welding inside large HDPE pipes. After the welding strip is pressed against the inner wall of the HDPE pipe, it is fully in contact with the inner wall of the HDPE pipe and is evenly heated during the welding process, which can better melt and form a high-strength welding layer. This close contact effectively eliminates the gaps or discontinuities that may occur during the welding process of the inner wall, thereby significantly improving the sealing and anti-leakage performance of the joint;

[0013] Sleeving the welding tape on the outside of the internal support device and reserving a repair welding area can effectively make up for the dimensional tolerance problem that may exist in the production process of the welding tape, so that the produced welding tape can adapt to HDPE pipes of different sizes, significantly improving the adaptability of the welding tape. In actual production, if the diameter of the HDPE pipe is too large, the length of the welding tape can be appropriately reduced and the number of repair welding areas can be increased, such as setting two sections of repair welding areas; the repair welding area is reinforced by extrusion welding to make up for the welding blind area or insufficient welding quality that may exist at the head and tail ends in the conventional electric fusion welding method. The addition of the repair welding process effectively avoids the welding weak points caused by the incomplete fusion of the head and tail welding, ensuring the sealing and mechanical properties of the pipe joint under pressure environment;

[0014] The large HDPE pipe joint welding method provided by the present invention effectively solves the problem of weak inner wall welding of large HDPE pipe joints in the prior art, greatly improves welding strength, sealing and reliability, reduces the risk of welding failure, and improves construction efficiency and applicability.

[0015] Preferably, before aligning the joint of the HDPE pipe in S1, the joint area of ​​the HDPE pipe is first polished and cleaned.

[0016] The joint area of ​​the HDPE pipe may be attached with dust, oil, oxide layer or other impurities during transportation, storage or construction, which will hinder the effective melting of the welding strip and the pipe joint area. Through grinding and cleaning, these impurities can be removed to provide a clean and unobstructed surface for welding, thereby ensuring that the welding strip is in full contact with the inner wall of the pipe and improving the welding effect.

[0017] Preferably, the method further comprises: S4. performing fillet welding on the side edge of the welding strip and the inner wall of the HDPE pipe, and grinding the fillet weld.

[0018] On the one hand, fillet welding the side of the welding strip to the inner wall of the HDPE pipe can form an additional welding support structure, thereby reinforcing the connection between the welding strip and the inner wall of the pipe. This fillet weld is equivalent to forming reinforcement points on both sides of the welding area, which significantly enhances the mechanical strength of the entire welded joint and better withstands external tensile, bending and shear forces. On the other hand, due to the large diameter of large HDPE pipes, the flow rate and flow velocity in the pipe are high, and the surface of the fillet weld is smoother after grinding, which can reduce the resistance and turbulence of the fluid when it flows through the welded joint, helping to improve the transportation efficiency of the pipeline, while reducing the wear of the weld area and improving the stability of the weld area.

[0019] Preferably, it also includes: S5. Perform a spark test after the HDPE pipe welding is completed: move the probe of the spark tester along the weld, the moving speed of the spark tester probe does not exceed 40 cm / second and is not less than 5 cm / second. If sparks appear, repair the area where the sparks appear until all welds pass the spark test.

[0020] For large HDPE pipes, the tightness of the welded joints is directly related to the safety of the pipes. Spark testing can detect possible tiny leaks or discontinuities in the welding area, avoid leakage due to poor sealing during the use of the pipe, and ensure that the welded joints have good sealing performance; the probe movement speed of the spark tester is set to no more than 40 cm / s and no less than 5 cm / s, which can achieve high detection efficiency while ensuring detection accuracy, avoiding situations where too fast movement leads to missed detection or too slow movement affects the construction progress.

[0021] Preferably, the height of the repair welding area is 10CM to 15CM.

[0022] The height of the repair welding area is set to 10cm to 15cm, providing a reasonable and sufficient repair welding operation space. Such a height can effectively accommodate the welding materials and hot melt area required during the repair welding process, avoiding uneven or incomplete welding due to insufficient space, thereby ensuring welding quality.

[0023] Preferably, the internal support device includes a support frame and a plurality of arc-shaped support plates, each arc-shaped support plate is connected to the support frame by at least one set of telescopic cylinders; the welding strip can be sleeved on the outer surface of the arc-shaped support plate, and the arc-shaped support plate is used to push the welding strip to press against the inner wall of the HDPE pipe joint area.

[0024] The outer surface of the arc support plate is in close contact with the welding strip, and its arc design can well match the inner wall shape of the HDPE pipe. The telescopic cylinder can accurately control the movement of the arc support plate, so that the welding strip is evenly close to the inner wall of the joint area, ensuring that the welding strip is closely attached to the inner wall of the HDPE pipe during welding, thereby improving the welding strength and sealing effect. When in use, the telescopic cylinder can be retracted first to facilitate the installation of the welding strip on the internal support device and the movement of the internal support device. After the internal support device is moved into place, the arc support plate can be evenly extended to push the welding strip against the inner wall of the HDPE pipe joint area, which is well adapted to large HDPE pipes of different diameters, greatly improving the versatility and adaptability of the internal support device.

[0025] Preferably, the number of the arc-shaped support plates is at least three, the angles between adjacent arc-shaped support plates are the same, and the curvature of the outer surface of the arc-shaped support plates is the same as the curvature of the inner surface of the HDPE pipe.

[0026] The setting of at least three arc-shaped support plates can form a uniform distribution of support points in the internal space of the HDPE pipe, ensuring that the pressure distribution is more uniform when the welding strip fits the inner wall of the HDPE pipe, avoiding local poor fitting or deformation of the welding strip due to uneven support. The angles between adjacent arc-shaped support plates are the same, which can achieve uniform distribution of force, making the support device more stable as a whole and the force more balanced during welding. The curvature of the outer surface of the arc-shaped support plate is the same as the curvature of the inner surface of the HDPE pipe, achieving a perfect match between the arc-shaped support plate and the inner wall of the pipe. This design can ensure that the welding strip fits tightly against the inner wall of the pipe, avoiding problems such as uneven fitting or loose contact.

[0027] Preferably, at least two thermal fuses are arranged on the surface of the welding strip in contact with the HDPE pipe, and the thermal fuses are wound in a multi-row overlapping manner along the length direction of the welding strip.

[0028] By increasing the number of thermal fuses, the welding strength between the welding strip and the HDPE pipe joint area can be significantly improved. The overlapping winding of multiple rows of thermal fuses further expands the melting area in the welding area, which helps to enhance the bearing capacity of the welding interface and ensure the stability and safety of the welding area under high pressure or heavy load conditions.

[0029] Preferably, at least two groups of thermal fuses are arranged on the surface where the welding strip contacts the HDPE pipe. One group of thermal fuses includes two thermal fuses. The distance between two adjacent groups of thermal fuses is 10CM to 15CM. The distance between two adjacent thermal fuses in the same group of thermal fuses is 4CM to 6CM.

[0030] The intra-group spacing and inter-group spacing of the thermal fuses are optimized, and the optimized design of the spacing between two adjacent thermal fuses in the same group can effectively improve the welding strength of the local welding area, ensure that each group of thermal fuses forms a solid welding point during the welding process, so that the local area has sufficient strength to withstand higher internal pressure and external force; the reasonable spacing design between two adjacent groups of thermal fuses ensures that the welding strength of the welding strip is evenly distributed as a whole, thereby avoiding the phenomenon of uneven strength of the welding strip along the welding interface, and effectively improving the overall stability of the welding joint.

[0031] In a second aspect, the present invention provides a pipe system, which is welded using the above-mentioned large HDPE pipe joint welding method, including two HDPE pipes and two welding strips, one welding strip is welded to the inner wall of the two HDPE pipe joints, and the other welding strip is welded to the outer wall of the two HDPE pipe joints, and the side of the welding strip located in the HDPE pipe forms a fillet weld with the inner wall of the HDPE pipe.

[0032] The pipe system provided by the present invention forms an inner and outer double-layer welded structure by welding welding strips on the inner and outer walls of the joint of two HDPE pipes, which can significantly enhance the overall strength and pressure bearing capacity of the joint area. The synergistic effect of the inner wall welding strip and the outer wall welding strip avoids the failure of a single welding structure due to local stress concentration, ensuring the long-term stable operation of the pipe system under high pressure conditions. The fillet weld forms a transition between the side of the inner wall welding strip and the inner wall of the HDPE pipe, which can reduce the resistance and turbulence of the fluid when it flows through the welded joint, help improve the transportation efficiency of the pipeline, and at the same time reduce the wear of the weld area and improve the stability of the welding area.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The large HDPE pipe joint welding method provided by the present invention uses a welding strip in the internal area of ​​the HDPE pipe joint and uses an internal support device to support and position the welding strip, so that welding reinforcement can be completed in the inner wall area of ​​the pipe joint. Compared with the traditional HDPE pipe welding method, this method performs reinforcement welding from the inside of the HDPE pipe, which can greatly improve the overall welding strength of the joint and reduce the risk of welding failure;

[0035] 2. The large HDPE pipe joint welding method provided by the present invention effectively solves the problem of loose inner wall welding of large HDPE pipe joints in the prior art, greatly improves welding strength, sealing and reliability, reduces the risk of welding failure, and improves construction efficiency and applicability.

[0036] 3. The pipe system provided by the present invention can significantly enhance the overall strength and pressure bearing capacity of the joint area by welding welding strips on the inner wall and outer wall of the joint of two HDPE pipes respectively to form an inner and outer double-layer welding structure. The synergistic effect of the inner wall welding strip and the outer wall welding strip can avoid the failure of a single welding structure due to local stress concentration, and ensure the long-term stable operation of the pipe system under high pressure conditions. The fillet weld forms a transition between the side of the inner wall welding strip and the inner wall of the HDPE pipe, which can reduce the resistance and turbulence of the fluid when it flows through the welded joint, help improve the transportation efficiency of the pipeline, and at the same time reduce the wear of the weld area and improve the stability of the welding area. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a flow chart of the welding method for large HDPE pipe joints;

[0038] Figure 2 This is a state diagram when the internal support device pushes the welding strip to press against the inner wall of the HDPE pipe joint area;

[0039] Figure 3 It is a schematic diagram of the welding strip;

[0040] Figure 4 This is a schematic diagram of the fillet weld between the side of the welding strip and the inner wall of the HDPE pipe;

[0041] Figure 5 This is a partial schematic diagram of the pipe system provided in Example 2.

[0042] Markings in the figure:

[0043] 1-welding strip, 11-thermal fuse, 2-internal support device, 21-support frame, 22-arc support plate, 23-telescopic cylinder, 10-repair welding area, 100-HDPE pipe. DETAILED DESCRIPTION

[0044] The present invention is further described in detail below in conjunction with specific embodiments. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0045] Unless otherwise specified, in the description of the specific embodiments of the present invention, the terms indicating the orientation or position relationship such as "up", "down", "left", "right", "center", "inside", "outside", etc. are all based on the expression of the orientation or position relationship shown in the drawings, or are the orientation or position relationship when the invented product / equipment / device is usually used. These terms of orientation or position relationship are only for the convenience of describing the scheme of the present invention or simplifying the description in the specific embodiments, so as to facilitate the technicians to quickly understand the scheme, and do not indicate or imply that a specific device / component / element must have a specific orientation, or be constructed and operated in a specific position relationship, and therefore cannot be understood as a limitation on the present invention.

[0046] In addition, if the terms "horizontal", "vertical", "overhanging", "parallel" and the like appear, it does not mean that the corresponding devices / components / elements are required to be absolutely horizontal or vertical or overhanging or parallel, but may be slightly tilted or have deviations. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but may be slightly tilted. Alternatively, it can be simplified to mean that the corresponding devices / components / elements are set in directions such as "horizontal", "vertical", "overhanging", "parallel", etc., and can have an error / deviation of ±10% relative to the corresponding direction setting, more preferably an error / deviation within ±8%, more preferably an error / deviation within ±6%, more preferably an error / deviation within ±5%, and more preferably an error / deviation within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its role in the scheme of the present invention.

[0047] In addition, the expressions “first”, “second”, “third”, etc., which appear in the terms, are merely used to distinguish the description of the same or similar components and should not be understood as emphasizing or implying the relative importance of specific components.

[0048] In addition, in the description of the embodiments of the present invention, "several", "plurality" and "a number" represent at least 2. It can be any number such as 2, 3, 4, 5, 6, 7, 8, 9, and even more than 9.

[0049] In addition, in the description of the technical solution of the present invention, unless otherwise clearly specified / defined / restricted, the terms "set", "install", "connect", "connected", "provided with", "laid", and "arranged" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, and can be welding, riveting, bolting, threading, and other commonly used connection means in the field. This connection can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the internal connection of two elements.

[0050] Example 1

[0051] This embodiment provides a large HDPE pipe joint welding method for performing electric hot-melt welding on the inner walls of joints of adjacent large HDPE pipes (with an inner diameter of more than 3 meters and a single section weight of more than 1 ton).

[0052] like Figure 1 As shown, the large HDPE pipe joint welding method includes the following steps:

[0053] S1. First, grind and clean the joint area of ​​the two sections of HDPE pipe 100 to be welded. Specifically, a grinder can be used to grind the joints of the two sections of HDPE pipe 100 to be welded, and more volatile alcohol can be used to wipe the joints of the HDPE pipe 100 to be welded during cleaning. Dust, oil, oxide layer or other impurities may be attached to the joint area of ​​the HDPE pipe 100 during transportation, storage or construction, and these pollutants will hinder the effective melting of the welding strip 1 and the pipe joint area. By grinding and cleaning, these impurities can be removed to provide a clean and unobstructed surface for welding, thereby ensuring that the welding strip 1 is in full contact with the inner wall of the pipe and improving the welding effect.

[0054] Use a crane to adjust the two sections of HDPE pipe 100 to be welded, align the joints of the HDPE pipe 100, align the axes of the joints of the two sections of HDPE pipe 100 to be welded, put the welding strip 1 on the internal support device 2 and reserve a repair welding area 10, which is located between the head end and the tail end of the welding strip 1.

[0055] Specifically, in this embodiment, the internal support device 2 includes a support frame 21 and a plurality of arc-shaped support plates 22. Each arc-shaped support plate 22 is connected to the support frame 21 through at least one set of telescopic cylinders 23; the welding strip 1 can be sleeved on the outer surface of the arc-shaped support plate 22, and the arc-shaped support plate 22 is used to push the welding strip 1 to press against the inner wall of the joint area of ​​the HDPE pipe 100.

[0056] by Figure 2 For example, Figure 2 The middle support frame 21 extends in six directions, and a group of ( Figure 2 The telescopic cylinders 23 are connected to an arc-shaped support plate 22. In this embodiment, the telescopic cylinders 23 can be hydraulic cylinders, air cylinders or electric cylinders commonly used in industrial production. The welding strip 1 is sleeved on the outer surfaces of the six arc-shaped support plates 22, and the virtual circle formed by the outer surfaces of the six arc-shaped support plates 22 is concentric with the HDPE pipe 100.

[0057] The outer surface of the arc support plate 22 is in close contact with the welding strip 1, and its arc design can well match the inner wall shape of the HDPE pipe 100. The telescopic cylinder 23 can accurately control the movement of the arc support plate 22, so that the welding strip 1 is evenly attached to the inner wall of the joint area, ensuring that the welding strip 1 is closely attached to the inner wall of the HDPE pipe 100 during welding, thereby improving the welding strength and sealing effect;

[0058] When in use, the telescopic cylinder 23 can be retracted first to facilitate the installation of the welding strip 1 on the internal support device 2, and it can also facilitate the movement of the internal support device 2 in the HDPE pipe 100. After the internal support device 2 moves into place, the arc support plate 22 can be evenly extended (for example, simultaneously extended) to push the welding strip 1 against the inner wall of the joint area of ​​the HDPE pipe 100, which is very suitable for large HDPE pipes 100 of different diameters, greatly improving the versatility and adaptability of the internal support device 2.

[0059] Furthermore, in this embodiment, the number of the arc-shaped support plates 22 is at least three, for example, three, four, or five, and preferably the number of the arc-shaped support plates 22 is six; the angles between adjacent arc-shaped support plates 22 are the same, so that Figure 2 For example, the angle α between adjacent arc-shaped support plates 22 is 60°. Figure 2 The middle dashed line is the central axis of the arc-shaped support plate 22. The curvature of the outer surface of the arc-shaped support plate 22 is the same as the curvature of the inner surface of the HDPE pipe 100.

[0060] The provision of at least three arc-shaped support plates 22 can form a uniform distribution of support points in the internal space of the HDPE pipe 100, ensuring that the pressure distribution of the welding strip 1 is more uniform when it fits against the inner wall of the HDPE pipe 100, thereby avoiding poor local fitting or deformation of the welding strip 1 due to uneven support. The angles between adjacent arc-shaped support plates 22 are the same, which can achieve uniform distribution of force, making the supporting device more stable as a whole and the force more balanced during welding. The curvature of the outer surface of the arc-shaped support plate 22 is the same as the curvature of the inner surface of the HDPE pipe 100, achieving a perfect match between the arc-shaped support plate 22 and the inner wall of the pipe. This design can ensure that the welding strip 1 fits tightly against the inner wall of the pipe, avoiding the problems of uneven fitting or loose contact.

[0061] like Figure 2 As shown, in this embodiment, the repair welding area 10 is located between the head end and the tail end of the welding strip 1. Figure 3 As shown, the welding strip 1 can be a rectangular strip welding strip, and the length of the welding strip 1 can be slightly smaller than the inner circumference of the HDPE pipe 100. Further, the inner circumference of the HDPE pipe 100 minus the length of the welding strip 1 can be equal to 10CM to 15CM, that is, Figure 2As shown, the height H of the repair welding area 10 is 10CM to 15CM. Setting the height of the repair welding area 10 to 10cm to 15cm provides a reasonable and sufficient repair welding operation space. Such a height can effectively accommodate the welding materials and hot melt area required during the repair welding process, avoiding uneven or incomplete welding due to insufficient space, thereby ensuring welding quality.

[0062] Furthermore, in this embodiment, at least two thermal fuses 11 are arranged on the surface where the welding strip 1 contacts the HDPE pipe 100 , and the thermal fuses 11 are wound in a multi-row overlapping manner along the length direction of the welding strip 1 .

[0063] Furthermore, at least two groups of thermal fuses 11 are arranged on the surface where the welding strip 1 contacts the HDPE pipe 100. One group of thermal fuses 11 includes two thermal fuses 11. The spacing between two adjacent groups of thermal fuses 11 is 10CM to 15CM. The spacing between two adjacent thermal fuses 11 in the same group of thermal fuses 11 is 4CM to 6CM.

[0064] Specifically, Figure 3 For example, the hot fuse 11 can use copper wire, and two groups of hot fuses 11 can be set on one side of the welding strip 1 close to the HDPE pipe 100, and the distance D between two adjacent groups of hot fuses 11 is 10CM to 15CM. One group of hot fuses 11 includes two hot fuses 11 wound in a serpentine multi-row superposition manner along the length direction of the welding strip 1, and the distance d between two adjacent hot fuses 11 in the same group of hot fuses 11 is 4CM to 6CM. The positions of the two groups of hot fuses 11 can be as close to the edge of the welding strip 1 as possible, and the hot fuses 11 can be extended from the side of the welding strip 1 to facilitate connection with the electric fusion welding machine.

[0065] By increasing the number of thermal fuses 11, the welding strength of the joint area between the welding strip 1 and the HDPE pipe 100 can be significantly improved. The overlapping winding of multiple rows of thermal fuses 11 further expands the melting area in the welding area, which helps to enhance the bearing capacity of the welding interface and ensure the stability and safety of the welding area under high pressure or heavy load conditions. The optimization of the intra-group spacing and inter-group spacing of the thermal fuses 11 and the optimization design of the spacing between two adjacent thermal fuses 11 in the same group of thermal fuses 11 can effectively improve the welding strength of the local welding area, ensure that each group of thermal fuses 11 forms a firm welding point during the welding process, so that the local area has sufficient strength to withstand high internal pressure and external force; the reasonable spacing design between two adjacent groups of thermal fuses 11 ensures that the welding strength of the welding strip 1 is evenly distributed as a whole, thereby avoiding the phenomenon of uneven strength of the welding strip 1 along the welding interface, and effectively improving the overall stability of the welding joint.

[0066] The internal support device 2 is moved (for example, a transfer trolley can be used to transport the internal support device 2) to the joint of the adjacent HDPE pipe 100. The movement of the telescopic cylinder 23 is controlled to drive the arc support plate 22 to gradually open the welding strip 1, and the internal support device 2 is adjusted so that the welding strip 1 is pressed against the inner wall of the joint area of ​​the HDPE pipe 100.

[0067] S2. Connect the hot fuse 11 of the welding strip 1 to the welding machine, and perform electric fusion welding on the joint of the HDPE pipe 100. After the electric fusion welding is completed, it can be cooled for 45 minutes to 60 minutes until the weld is firm. After the welding of the welding strip 1 is completed, remove the internal support device 2.

[0068] S3. Extrusion welding is performed on the repair welding area 10. For example, the repair welding area 10 can be welded by manually operating an extrusion welding machine, and the repair welding area 10 can be fully welded.

[0069] The large HDPE pipe 100 joint welding method provided in this embodiment uses a welding strip 1 in the internal area of ​​the HDPE pipe 100 joint and uses an internal support device 2 to support and position the welding strip 1, so that welding reinforcement can be completed in the inner wall area of ​​the pipe joint. Compared with the traditional HDPE pipe welding method, this method performs reinforcement welding from the inside of the HDPE pipe 100, which can greatly improve the overall welding strength of the joint and reduce the risk of welding failure.

[0070] This method uses an internal support device 2 to press the welding strip 1 against the inner wall of the joint area from the inside of the HDPE pipe 100, thereby solving the problem of loose welding inside the large HDPE pipe 100. After the welding strip 1 is pressed against the internal support device 2, it is in full contact with the inner wall of the HDPE pipe 100, and is evenly heated during the welding process, so that it can melt better and form a high-strength welding layer. This close contact effectively eliminates gaps or discontinuities that may occur during the inner wall welding process, thereby significantly improving the sealing and anti-leakage performance of the joint.

[0071] Sleeving the welding strip 1 on the outside of the internal support device 2 and reserving the repair welding area 10 can effectively compensate for the dimensional tolerance problem that may exist in the production process of the welding strip 1, so that the produced welding strip 1 can adapt to HDPE pipes 100 of different sizes, significantly improving the adaptability of the welding strip 1. In actual production, if the diameter of the HDPE pipe 100 is too large, the length of the welding strip 1 can be appropriately reduced and the number of repair welding areas 10 can be increased, for example, two sections of repair welding areas 10 can be set; the repair welding area 10 is reinforced by extrusion welding to compensate for the welding blind spots or insufficient welding quality that may exist at the head and tail ends in the conventional electric fusion welding method. The addition of the repair welding process effectively avoids the welding weak points caused by the incomplete fusion of the head and tail welding, and ensures the sealing and mechanical properties of the pipeline joint under pressure.

[0072] The large HDPE pipe 100 joint welding method provided in this embodiment effectively solves the problem of loose inner wall welding of large HDPE pipe 100 joints in the prior art, greatly improves welding strength, sealing and reliability, reduces the risk of welding failure, and improves construction efficiency and applicability.

[0073] Further, such as Figure 1 As shown, the large HDPE pipe joint welding method of this embodiment further includes: S4. Fillet welding the side of the welding strip 1 and the inner wall of the HDPE pipe 100, and grinding the fillet weld. Figure 4 As shown, Figure 4 The blackened part is where the fillet weld is located, and the extrusion welding machine can be manually operated to perform extrusion welding along the side of the welding strip 1. On the one hand, by performing fillet welding on the side of the welding strip 1 and the inner wall of the HDPE pipe 100, an additional welding support structure can be formed, thereby reinforcing the connection between the welding strip 1 and the inner wall of the pipe. This fillet weld is equivalent to forming reinforcement points on both sides of the welding area, which significantly enhances the mechanical strength of the entire welded joint and better withstands external tensile, bending and shear forces. On the other hand, since the large HDPE pipe 100 has a large diameter and a high flow rate and velocity in the pipe, the surface of the fillet weld is smoother after grinding, which can reduce the resistance and turbulence of the fluid when it flows through the welded joint, and help improve the transportation efficiency of the pipeline, while reducing the wear of the weld area and improving the stability of the welding area.

[0074] Further, such as Figure 1 As shown, the large HDPE pipe joint welding method of this embodiment also includes: S5. After the HDPE pipe 100 is welded, a spark test is performed: the probe of the spark tester is moved along the weld, and the moving speed of the probe of the spark tester does not exceed 40 cm / second and is not less than 5 cm / second. If sparks appear, the spark area is repaired until the welds pass the spark test.

[0075] For large HDPE pipes 100, the sealing of the welded joints is directly related to the safety of the pipes. Spark testing can detect possible tiny leaks or discontinuities in the welding area, avoid leakage due to poor sealing during the use of the pipe, and ensure that the welded joints have good sealing performance; the probe movement speed of the spark tester is set to no more than 40 cm / s and no less than 5 cm / s, which can achieve high detection efficiency while ensuring detection accuracy, avoiding situations where too fast movement leads to missed detection or too slow movement affects the construction progress.

[0076] Example 2

[0077] This embodiment provides a pipe system, which is welded using the large HDPE pipe joint welding method provided in Example 1. Specifically, Figure 5 As shown, it includes two HDPE pipes 100 and two welding strips 1, one welding strip 1 is welded to the inner wall of the joint of the two HDPE pipes 100, and the other welding strip 1 is welded to the outer wall of the joint of the two HDPE pipes 100, and the side of the welding strip 1 located in the HDPE pipe 100 forms a fillet weld with the inner wall of the HDPE pipe 100 ( Figure 5 black part in the figure).

[0078] The pipe system provided in this embodiment forms an inner and outer double-layer welded structure by welding welding strips 1 on the inner and outer walls of the joints of two HDPE pipes 100, which can significantly enhance the overall strength and pressure bearing capacity of the joint area. The synergistic effect of the inner wall welding strip 1 and the outer wall welding strip 1 can avoid the failure of a single welding structure due to local stress concentration, and ensure the long-term stable operation of the pipe system under high pressure conditions. The fillet weld forms a transition between the side of the inner wall welding strip 1 and the inner wall of the HDPE pipe 100, which can reduce the resistance and turbulence of the fluid when it flows through the welded joint, help improve the transportation efficiency of the pipeline, and at the same time reduce the wear of the weld area and improve the stability of the welding area.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. 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 present invention.

Claims

1. A large HDPE pipe joint welding method, characterized in that: The following steps are involved: S1. Align the joint of the HDPE pipe (100), sleeve the welding strip (1) on the internal support device (2) and reserve a repair welding area (10), the repair welding area (10) is located between the head end and the tail end of the welding strip (1); Moving the internal support device (2) to the joint of the adjacent HDPE pipe (100), and adjusting the internal support device (2) so that the welding strip (1) is in tight contact with the inner wall of the joint area of ​​the HDPE pipe (100); S2. Connect the welding strip (1) to the welding machine, and perform electric fusion welding on the joint of the HDPE pipe (100). After the welding of the welding strip (1) is completed, remove the internal support device (2); S3. Perform extrusion welding on the repair welding area (10).

2. A large HDPE pipe joint welding method according to claim 1, characterized in that: Before aligning the joint of the HDPE pipe (100) in S1, the joint area of ​​the HDPE pipe (100) is polished and cleaned.

3. A large HDPE pipe joint welding method according to claim 1, characterized in that: Also includes: S4. Fillet weld the side of the welding strip (1) and the inner wall of the HDPE pipe (100), and grind the fillet weld.

4. A large HDPE pipe joint welding method according to claim 3, characterized in that: Also includes: S5. After the HDPE pipe (100) is welded, a spark test is performed: the probe of the spark tester is moved along the weld, and the moving speed of the spark tester probe does not exceed 40 cm / s and is not less than 5 cm / s. If sparks appear, the spark area is repaired until the weld passes the spark test.

5. A large HDPE pipe joint welding method according to claim 1, characterized in that: The height of the repair welding area (10) is 10CM to 15CM.

6. A large HDPE pipe joint welding method according to claim 1, characterized in that: The internal support device (2) comprises a support frame (21) and a plurality of arc-shaped support plates (22), each of which is connected to the support frame (21) via at least one set of telescopic cylinders (23); the welding strip (1) can be sleeved on the outer surface of the arc-shaped support plate (22), and the arc-shaped support plate (22) is used to push the welding strip (1) to press against the inner wall of the joint area of ​​the HDPE pipe (100).

7. A large HDPE pipe joint welding method according to claim 6, characterized in that: The number of the arc-shaped support plates (22) is at least three, the angles between adjacent arc-shaped support plates (22) are the same, and the curvature of the outer surface of the arc-shaped support plates (22) is the same as the curvature of the inner surface of the HDPE pipe (100).

8. A large HDPE pipe joint welding method according to claim 1, characterized in that: At least two thermal fuses (11) are arranged on the surface of the welding strip (1) in contact with the HDPE pipe (100), and the thermal fuses (11) are wound in a multi-row overlapping manner along the length direction of the welding strip (1).

9. A large HDPE pipe joint welding method according to claim 8, characterized in that: At least two groups of thermal fuses (11) are arranged on the surface where the welding strip (1) contacts the HDPE pipe (100), one group of thermal fuses (11) comprises two thermal fuses (11), the distance between two adjacent groups of thermal fuses (11) is 10 cm to 15 cm, and the distance between two adjacent thermal fuses (11) in the same group of thermal fuses (11) is 4 cm to 6 cm.

10. A pipe system, characterized in that: The method for welding a large HDPE pipe joint according to any one of claims 1 to 9 is used for welding, comprising two HDPE pipes (100) and two welding strips (1), wherein one welding strip (1) is welded to the inner wall of the joint of the two HDPE pipes (100), and the other welding strip (1) is welded to the outer wall of the joint of the two HDPE pipes (100), and the side edge of the welding strip (1) located inside the HDPE pipe (100) forms a fillet weld with the inner wall of the HDPE pipe (100).

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