A large HDPE pipe joint welding method and pipe body system

Abstract

The present application relates to the technical field of HDPE pipeline welding, in particular to a large HDPE pipeline joint welding method and a pipe body system, wherein the large HDPE pipeline joint welding method comprises the following steps: S1. Aligning the joints of the HDPE pipelines, sleeving the welding strip on the internal support device and reserving a repair welding area between the leading end and the trailing end of the welding strip; moving the internal support device to the joint of the adjacent HDPE pipeline, and adjusting the internal support device so that the welding strip is tightly abutted against the inner wall of the joint area of the HDPE pipeline; S2. Connecting the welding strip with the welding machine, and electrically melting and welding the joint of the HDPE pipeline; and removing the internal support device after the welding of the welding strip is completed; S3. Extruding and welding the repair welding area, which effectively solves the problem of the poor welding of the inner wall of the large HDPE pipeline joint in the prior art, greatly improves the welding strength, the sealing property and the reliability, reduces the risk of welding failure, and improves the construction efficiency and the applicability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of HDPE pipe welding, in particular to a large HDPE pipe joint welding method and pipe body system. BACKGROUND

[0002] HDPE pipe is a kind of pipe made of high-density polyethylene material (High Density Polyethylene), which has many advantages, such as reliable connection, impact resistance, not easy to crack, durable and corrosion resistance. Therefore, HDPE pipe has become the mainstream choice in water supply and drainage system. Generally, the overall performance of the pipe system often depends on its weakest link. For HDPE pipe, this weak point usually appears at the welded joint. Currently, there are two main ways of HDPE pipe welding in the industry:

[0003] The first is electric hot melt socket welding. The specific operation is: first, a specially designed electric melting pipe fitting is sleeved on the outside of the pipe, and then the pipe fitting is powered by a professional welding machine. 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 is hot melt butt welding. This method is to simultaneously contact the end faces of two pipes with a hot plate, and after the surface is melted, the hot plate is quickly removed, and the two ends are immediately pressed together. Keep a certain pressure until it cools down, and a joint with strength even exceeding the pipe itself can be formed.

[0005] However, when welding the joint of large HDPE pipe (inner diameter more than 3 meters, single section weight more than 1 ton), due to the large diameter of the large HDPE pipe, not only the welding strip needs to be used on the outside of the pipe joint, but also the inside of the large HDPE pipe joint needs to be welded. The above two commonly used welding methods cannot meet the internal reinforcement welding of large HDPE pipe joint, and direct application to large HDPE pipe joint welding will result in poor welding of large HDPE pipe, causing welding failure of large HDPE pipe. SUMMARY

[0006] The purpose of the present application is to overcome the shortcomings of the existing HDPE pipe welding method, which cannot reinforce the internal welding of large HDPE pipe, and is prone to cause welding failure of large HDPE pipe, and to provide a large HDPE pipe joint welding method and pipe body system.

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

[0008] S1. Align the joint of the HDPE pipe, sleeve the welding strip on the internal support device and reserve a repair welding area between the leading end and the trailing end of the welding strip; move the internal support device to the joint of the adjacent HDPE pipe, and adjust the internal support device so that the welding strip is tightly abutted against the inner wall of the joint area of the HDPE pipe;

[0009] S2. Connect the welding strip with the welding machine, and electrically fuse weld the joint of the HDPE pipe; after the welding strip is welded, remove the internal support device;

[0010] S3. Extrusion weld the repair welding area.

[0011] The large HDPE pipe joint welding method provided by the application can reinforce and weld from the inside of the HDPE pipe, greatly improve the overall welding strength of the joint, and reduce the risk of welding failure.

[0012] The welding strip is tightly abutted against the inner wall of the joint area from the inside of the HDPE pipe by using the internal support device, which solves the problem of insecure welding inside the large HDPE pipe. After the welding strip is tightly abutted against the inner wall by the internal support device, it is in full 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 leak-proof performance of the joint.

[0013] Sleeving the welding strip on the outside of the internal support device and reserving a repair welding area can effectively compensate for the size tolerance problem that may exist in the production process of the welding strip, so that the produced welding strip can adapt to HDPE pipes of different sizes, significantly improving the adaptability of the welding strip. In actual production, if the pipe diameter of the HDPE pipe is too large, the length of the welding strip can be appropriately reduced and the number of repair welding areas can be increased, for example, two repair welding areas are set. The repair welding area is reinforced by extrusion welding, which compensates for the welding blind area or insufficient welding quality that may exist at the leading end and the trailing end in the conventional electric fusion welding method. The addition of the repair welding process effectively avoids the weak points caused by incomplete fusion at the leading end and the trailing end, ensuring the sealing and mechanical properties of the pipe joint in a pressure environment.

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

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

[0016] The joint area of the HDPE pipe may be attached with dust, oil stains, oxidation layer or other impurities during transportation, storage or construction, which will hinder the effective melting of the welding strip and the joint area of the pipe. By polishing and cleaning, these impurities can be removed to provide a clean and obstacle-free surface for welding, so as to ensure that the welding strip is in full contact with the inner wall of the pipe and improve the welding effect.

[0017] Preferably, it further comprises: S4. Fillet welding the side edge of the welding strip and the inner wall of the HDPE pipe, and polishing the fillet weld.

[0018] On the one hand, the fillet welding of the side edge of the welding strip and the inner wall of the HDPE pipe can form an additional welding support structure to reinforce the connection between the welding strip and the inner wall of the pipe. This fillet weld forms a reinforcement point on both sides of the welding area, significantly enhancing the mechanical strength of the entire welded joint and better resisting external tensile, bending and shear forces. On the other hand, due to the large diameter of the large HDPE pipe, the flow rate and flow velocity in the pipe are high, and the polished surface of the fillet weld is smoother, which can reduce the resistance and turbulence of the fluid flowing through the welded joint, help to improve the conveying efficiency of the pipe, and at the same time reduce the wear of the welded joint area and improve the stability of the welded area.

[0019] Preferably, it further comprises: S5. After the welding of the HDPE pipe is completed, a spark test is performed: the probe of the spark tester is moved along the welded joint, the moving speed of the probe of the spark tester is not more than 40 cm / s and not less than 5 cm / s, if sparks appear, the area where the sparks appear is repaired until the welded joint passes the spark test.

[0020] For large HDPE pipes, the sealing performance of the welded joint is directly related to the safety of the pipe in use. The spark test can detect possible small leaks or discontinuities in the welded area, avoid leaks due to poor sealing during use, and ensure that the welded joint has good sealing performance; the moving speed of the probe of the spark tester is set to not more than 40 cm / s and not less than 5 cm / s, which can ensure the detection accuracy while achieving high detection efficiency, avoiding the situation that moving too fast leads to missed detection or moving too slow affects the construction progress.

[0021] Preferably, the height of the repair area is 10-15 cm.

[0022] The height of the repair welding area is set to 10-15 cm, which provides a reasonable and sufficient repair welding operation space. Such height can effectively accommodate the welding materials and hot melting area required in the repair welding process, avoid uneven or incomplete welding due to insufficient space, and thus ensure the welding quality.

[0023] Preferably, the internal support device comprises a support frame and a plurality of arc-shaped support plates, each arc-shaped support plate being 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 against the inner wall of the joint area of the HDPE pipe.

[0024] The outer surface of the arc-shaped support plate is in close contact with the welding strip, and the arc-shaped design can well match the shape of the inner wall of the HDPE pipe. The telescopic cylinder can accurately control the movement of the arc-shaped support plate, so that the welding strip is uniformly attached 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, improving the welding strength and sealing effect; during 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 position, the arc-shaped support plates can be uniformly extended to push the welding strip against the inner wall of the joint area of the HDPE pipe, which well adapts to large HDPE pipes of different diameters, greatly improving the versatility and adaptability of the internal support device.

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

[0026] The arrangement 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 is attached to the inner wall of the HDPE pipe, and avoiding local poor attachment 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 overall support device more stable and the stress during welding more balanced. The curvature of the outer surface of the arc-shaped support plate is the same as that of the inner surface of the HDPE pipe, achieving perfect matching of the arc-shaped support plate and the inner wall of the pipe. Such design can ensure that the welding strip is closely attached to the inner wall of the pipe, avoiding uneven attachment or insufficient contact.

[0027] Preferably, at least two hot melting wires are arranged on the surface of the welding strip in contact with the HDPE pipe, and the hot melting wires are wound in multiple rows in a stacked manner along the length direction of the welding strip.

[0028] By increasing the number of hot melting wires, the welding strength of the welding strip and the joint area of the HDPE pipe can be significantly improved. The multiple rows of hot melting wires wound in a stacked manner further expand the melting area in the welding area, which helps to enhance the load-bearing capacity of the welded joint, and ensures the stability and safety of the welding area under high pressure or heavy load conditions.

[0029] Preferably, the surface of the welding strip in contact with the HDPE pipe is provided with at least two groups of hot melting wires, one group of hot melting wires includes two hot melting wires, the distance between adjacent two groups of hot melting wires is 10-15 cm, and the distance between adjacent two hot melting wires in the same group of hot melting wires is 4-6 cm.

[0030] The distance between the hot melting wires in the group and the distance between the groups are optimized, and the optimized design of the distance between the adjacent two hot melting wires in the same group of hot melting wires can effectively improve the fusion strength of the local welding area, ensure that each group of hot melting wires forms a firm welding point during the welding process, and make the local area have sufficient strength to withstand high internal pressure and external force; the reasonable distance design between the adjacent two groups of hot melting wires ensures that the welding strength of the welding strip is uniformly distributed as a whole, thereby avoiding the uneven strength phenomenon of the welding strip along the welding interface and effectively improving the overall stability of the welded joint.

[0031] In the second aspect, the present application provides a pipe system welded by the large HDPE pipe joint welding method, which comprises two HDPE pipes and two welding strips, one welding strip is welded to the inner wall of the joint of the two HDPE pipes, and the other welding strip is welded to the outer wall of the joint of the two HDPE pipes, and the side edge of the welding strip in the HDPE pipe forms a fillet weld with the inner wall of the HDPE pipe.

[0032] The pipe system provided by the present application can significantly enhance the overall strength and pressure-bearing capacity of the joint area by welding welding strips on the inner wall and the outer wall of the joint of the two HDPE pipes to form an inner-outer double-layer welding structure. 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 and ensures the long-term stable operation of the pipe system under high pressure conditions. The fillet weld forms a transition between the side edge of the inner wall welding strip and the inner wall of the HDPE pipe, which can reduce the resistance and turbulence of the fluid flowing through the welded joint, help to improve the conveying efficiency of the pipeline, and at the same time reduce the wear of the welded area and improve the stability of the welded area.

[0033] Compared with the prior art, the present application has the following advantages:

[0034] 1. The large HDPE pipe joint welding method provided by the present application 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 and reinforcement can be completed in the inner wall area of the pipe joint. Compared with the traditional HDPE pipe welding method, the present method reinforces and welds 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 application effectively solves the problem of weak welding of the inner wall of the large HDPE pipe joint in the prior art, greatly improves the welding strength, sealing performance and reliability, reduces the risk of welding failure, and improves the construction efficiency and applicability.

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

[0037] Figure 1 It is a flow chart of the large HDPE pipe joint welding method;

[0038] Figure 2 It is a state diagram when the inner support device pushes the welding strip 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 It is a schematic diagram of the fillet weld between the side edge of the welding strip and the inner wall of the HDPE pipe;

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

[0042] Markings in the figure:

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

[0044] The present application will be further described in detail below in conjunction with specific embodiments. However, it should not be understood that the scope of the above-mentioned subject matter of the present application is limited to the following examples only, and any technology realized based on the content of the present application falls within the scope of the present application.

[0045] In the description of the embodiments of the present application, the terms of orientation or positional relationship such as "upper", "lower", "left", "right", "center", "inner", "outer", and the like, are expressed based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product / device / apparatus of the present application is usually used. These terms of orientation or positional relationship are only for the convenience of describing the present application or simplifying the description in the embodiments, and for the convenience of the skilled person 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 positional relationship, and therefore cannot be understood as a limitation on the present application.

[0046] In addition, the terms "horizontal", "vertical", "suspended", "parallel", and the like, do not mean that the corresponding device / component / element must be absolutely horizontal or vertical or suspended or parallel, but can be slightly inclined or deviated. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined. Alternatively, it can be simplified to understand that the corresponding device / component / element is arranged in the direction of "horizontal", "vertical", "suspended", "parallel", etc., and can have an error / deviation of ±10% relative to the corresponding direction, more preferably an error / deviation of ±8% or less, more preferably an error / deviation of ±6% or less, more preferably an error / deviation of ±5% or less, and more preferably an error / deviation of ±4% or less. 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 application.

[0047] In addition, the terms "first", "second", "third", and the like, are only used to distinguish the same or similar components for description, and should not be understood as emphasizing or implying the relative importance of a specific component.

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

[0049] In addition, in the description of the technical scheme of the present application, unless otherwise specified / limited / limited, the terms "arrangement", "installation", "connection", "connection", "provided with", "laid", "arrangement" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected, such as welding, riveting, bolting, screwing, etc. The connection means commonly used in the art. Such connection can be mechanical connection, or electrical connection or communication connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication between two elements.

[0050] Example 1

[0051] This embodiment provides a large HDPE pipe joint welding method for performing electric heat fusion welding on the inner walls of the joints of adjacent large HDPE pipes (with an inner diameter of more than 3 meters and a single section weighing 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 joint of the two sections of HDPE pipe 100 to be welded. When cleaning, more volatile alcohol can be used to wipe the joint of the HDPE pipe 100 to be welded. During transportation, storage or construction, the joint area of ​​the HDPE pipe 100 may be adhered with dust, oil, oxide layer or other impurities. 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, providing a clean, 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 tape 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 tape 1.

[0055] Specifically, in this embodiment, the internal support device 2 includes a support frame 21 and a plurality of curved support plates 22. Each curved support plate 22 is connected to the support frame 21 via at least one set of telescopic cylinders 23. The welding strip 1 can be sleeved onto the outer surface of the curved support plate 22, and the curved support plate 22 is used to push the welding strip 1 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 set of ( Figure 2 Telescopic cylinders 23 (two in the figure) are each connected to a curved support plate 22. In this embodiment, the telescopic cylinders 23 can be hydraulic cylinders, pneumatic cylinders, or electric cylinders commonly used in industrial production. The welding strip 1 is sleeved onto the outer surfaces of the six curved support plates 22. The virtual circle formed by the outer surfaces of the six curved support plates 22 is concentric with the HDPE pipe 100.

[0057] The outer surface of the arc-shaped support plate 22 is in close contact with the welding strip 1, and the arc-shaped design can well match the inner wall shape of the HDPE pipeline 100. The telescopic cylinder 23 can accurately control the movement of the arc-shaped support plate 22, so that the welding strip 1 is uniformly 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 pipeline 100 during welding, thereby improving the welding strength and sealing effect.

[0058] In use, the telescopic cylinder 23 can be retracted first, which facilitates the installation of the welding strip 1 on the internal support device 2 and also facilitates the movement of the internal support device 2 in the HDPE pipeline 100. After the internal support device 2 is moved into position, the arc-shaped support plates 22 can be uniformly extended (e.g., simultaneously extended) to push the welding strip 1 against the inner wall of the joint area of the HDPE pipeline 100, which well adapts to large HDPE pipelines 100 of different diameters and greatly improves the versatility and adaptability of the internal support device 2.

[0059] Further, the number of arc-shaped support plates 22 in the present embodiment is at least three, for example, three, four, or five, and preferably six. Figure 2 For example, the angle α between adjacent arc-shaped support plates 22 is 60°, Figure 2 The dashed line is the central axis of the arc-shaped support plate 22. The outer surface of the arc-shaped support plate 22 has the same curvature as the inner surface of the HDPE pipeline 100.

[0060] The arrangement of at least three arc-shaped support plates 22 can form a uniform distribution of support points in the internal space of the HDPE pipeline 100, ensuring that the welding strip 1 is uniformly pressed against the inner wall of the HDPE pipeline 100, and avoiding local poor adhesion or deformation of the welding strip 1 due to uneven support. The same angle between adjacent arc-shaped support plates 22 can achieve uniform force distribution, making the overall support device more stable and the stress during welding more balanced. The outer surface of the arc-shaped support plate 22 has the same curvature as the inner surface of the HDPE pipeline 100, achieving perfect matching of the arc-shaped support plate 22 with the inner wall of the pipeline. This design can ensure that the welding strip 1 is closely attached to the inner wall of the pipeline, avoiding uneven adhesion or insufficient contact.

[0061] As shown in FIG. 1, Figure 2 In the present embodiment, the repair welding area 10 is located between the leading end and the trailing end of the welding strip 1. As shown in FIG. 1, Figure 3 The welding strip 1 can be a rectangular strip, and the length of the welding strip 1 can be slightly less than the inner circumference of the HDPE pipeline 100. Further, the inner circumference of the HDPE pipeline 100 minus the length of the welding strip 1 can be equal to 10-15 cm, i.e., Figure 2As shown, the height H of the repair welding area 10 is 10-15 cm. The height of the repair welding area 10 is set to 10-15 cm to provide a reasonable and sufficient repair welding operation space. Such a height can effectively accommodate the welding materials and hot melting area required in the welding process, avoid uneven or incomplete welding due to insufficient space, and thus ensure the welding quality.

[0062] Further, the surface of the welding strip 1 in contact with the HDPE pipe 100 is provided with at least two hot melting wires 11, which are wound in a multi-row stacked manner along the length direction of the welding strip 1.

[0063] Further, the surface of the welding strip 1 in contact with the HDPE pipe 100 is provided with at least two groups of hot melting wires 11, each group of hot melting wires 11 including two hot melting wires 11, the spacing between adjacent two groups of hot melting wires 11 being 10-15 cm, and the spacing between adjacent two hot melting wires 11 in the same group of hot melting wires 11 being 4-6 cm.

[0064] Specifically, taking the copper wire as an example, the surface of the welding strip 1 in contact with the HDPE pipe 100 can be provided with two groups of hot melting wires 11, the spacing D between adjacent two groups of hot melting wires 11 being 10-15 cm, each group of hot melting wires 11 including two hot melting wires 11 wound in a multi-row stacked manner along the length direction of the welding strip 1, and the spacing d between adjacent two hot melting wires 11 in the same group of hot melting wires 11 being 4-6 cm. Figure 3

[0065] By increasing the number of hot melting wires 11, the welding strength of the joint area of the welding strip 1 and the HDPE pipe 100 can be significantly improved. The multi-row stacked winding of the hot melting wires 11 further expands the melting area in the welding area, which helps to enhance the carrying 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 hot melting wires 11, as well as the optimization design of the spacing between adjacent two hot melting wires 11 in the same group of hot melting wires 11, can effectively improve the welding strength of the local welding area and ensure that each group of hot melting wires 11 forms a firm 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 adjacent two groups of hot melting wires 11 ensures that the welding strength of the welding strip 1 is uniformly distributed as a whole, thereby avoiding 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, the internal support device 2 can be transported by using a transfer trolley) to the joint of the adjacent HDPE pipe 100. The movement of the telescopic cylinder 23 drives the arc-shaped support plate 22 to gradually support the welding strip 1, and the internal support device 2 is adjusted to make the welding strip 1 abut against the inner wall of the joint area of the HDPE pipe 100.

[0067] S2. The hot melting wire 11 of the welding strip 1 is connected to the welding machine, and the joint of the HDPE pipe 100 is electrically fused and welded. After the electrically fused and welded joint is completed, the welding joint can be cooled for 45-60 minutes to wait for the welding seam to be firm. After the welding of the welding strip 1 is completed, the internal support device 2 is removed.

[0068] S3. The repair welding area 10 is subjected to extrusion welding, for example, the repair welding area 10 can be welded by manually operating an extrusion welding machine. The repair welding area 10 can be fully welded.

[0069] The large HDPE pipe 100 joint welding method provided in the embodiment uses the welding strip 1 in the internal area of the joint of the HDPE pipe 100, and uses the internal support device 2 to support and position the welding strip 1, so that the welding reinforcement can be completed in the inner wall area of the pipe joint. Compared with the traditional HDPE pipe welding method, the welding reinforcement is performed 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] The method uses the internal support device 2 to abut the welding strip 1 against the inner wall of the joint area from the inside of the HDPE pipe 100, which solves the problem of weak welding in the internal area of the large HDPE pipe 100. After the welding strip 1 is abutted against the inner wall by the internal support device 2, the welding strip 1 is in full contact with the inner wall of the HDPE pipe 100, is uniformly heated during the welding process, and can be better melted to form a high-strength welding layer. This close contact effectively eliminates the gaps or discontinuities that may occur during the welding of the inner wall, thereby significantly improving the sealing performance and leak-proof performance of the joint.

[0071] The welding strip 1 is sleeved on the outside of the internal support device 2 and has the repair welding area 10, which can effectively compensate for the size 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, and the adaptability of the welding strip 1 is significantly improved. In actual production, if the pipe diameter of the HDPE pipe 100 is too large, the length of the welding strip 1 can be appropriately reduced and the number of the repair welding area 10 can be increased, for example, two repair welding areas 10 are provided. The repair welding area 10 is subjected to reinforcement welding by extrusion welding, which compensates for the welding blind area or insufficient welding quality that may exist at the beginning and end of the conventional electrically fused welding method. The addition of the repair welding process effectively avoids the welding weak points caused by incomplete fusion at the beginning and end of the welding, and ensures the sealing performance and mechanical performance of the pipe joint in a pressure environment.

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

[0073] Further, as shown in Figure 1 , the large HDPE pipe joint welding method further comprises: S4. Fillet welding is performed on the side edge of the welding strip 1 and the inner wall of the HDPE pipe 100, and the fillet weld is polished. Specifically, as shown in Figure 4 , Figure 4 The black part in the middle is the position of the fillet weld. The extrusion welding machine can be manually operated to perform extrusion welding along the side edge of the welding strip 1. On the one hand, the fillet welding of the side edge of the welding strip 1 and the inner wall of the HDPE pipe 100 can form an additional welding support structure, thereby reinforcing the connection between the welding strip 1 and the inner wall of the pipe. This fillet weld forms a reinforcing point on both sides of the welding area, significantly enhancing the mechanical strength of the entire welded joint and better resisting external tensile, bending and shear forces. On the other hand, due to the large diameter of the large HDPE pipe 100, the flow rate and flow velocity in the pipe are high. The polished surface of the fillet weld is smoother, which can reduce the resistance and turbulence of the fluid flowing through the welded joint, help improve the conveying efficiency of the pipe, and reduce the wear of the welded area and improve the stability of the welded area.

[0074] Further, as shown in Figure 1 , the large HDPE pipe joint welding method further comprises: S5. After the HDPE pipe 100 is welded, a spark test is performed: the probe of the spark tester is moved along the welded joint at a speed not greater than 40 cm / s and not less than 5 cm / s. If sparks appear, the area where the sparks appear is repaired until the welded joint passes the spark test.

[0075] For the large HDPE pipe 100, the sealing performance of the welded joint is directly related to the safety of the pipe in use. The spark test can detect possible small leaks or discontinuities in the welded area, avoid leaks due to poor sealing during use of the pipe, and ensure that the welded joint has good sealing performance. The moving speed of the probe of the spark tester is set to be not greater than 40 cm / s and not less than 5 cm / s, which can ensure the detection accuracy while achieving high detection efficiency, avoiding the situation that the detection is missed due to too fast movement or the construction progress is affected due to too slow movement.

[0076] Embodiment 2

[0077] The embodiment provides a pipe body system welded by using the large HDPE pipe joint welding method provided in embodiment 1. Specifically, as shown inFigure 5 As shown, two HDPE pipes 100 and two welding strips 1 are included, 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, the side edge of the welding strip 1 inside the HDPE pipe 100 forms a fillet weld with the inner wall of the HDPE pipe 100. Figure 5 The middle part is black.

[0078] The pipe system provided by the embodiment can significantly enhance the overall strength and pressure-bearing capacity of the joint area by welding the welding strip 1 to the inner wall and the outer wall of the joint of the two HDPE pipes 100 respectively to form a double-layer welding structure. The synergistic effect of the inner wall welding strip 1 and the outer wall welding strip 1 avoids the failure of a single welding structure due to local stress concentration and ensures the long-term stable operation of the pipe system under high pressure conditions. The fillet weld forms a transition between the side edge 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 flowing through the welded joint, help to improve the conveying efficiency of the pipe, and at the same time reduce the wear of the welded joint area and improve the stability of the welded area.

[0079] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principle of the present application shall be included in the protection scope of the present application.

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 pressed against 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. Extrusion welding is performed on the repair welding area (10); S4. Fillet weld the side of the welding strip (1) to the inner wall of the HDPE pipe (100), and grind the fillet weld.

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: S5. After the HDPE pipe (100) is welded, a spark test is performed: the probe of the spark tester is moved along the weld. 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 by welding until all welds pass the spark test.

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

5. A large HDPE pipe joint welding method according to claim 1, characterized in that: The internal support device (2) includes 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) against the inner wall of the joint area of ​​the HDPE pipe (100).

6. A large HDPE pipe joint welding method according to claim 5, 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).

7. A large HDPE pipe joint welding method according to claim 1, characterized in that: At least two thermal fuses (11) are provided 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).

8. A large HDPE pipe joint welding method according to claim 7, characterized in that: At least two groups of thermal fuses (11) are provided 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, and the spacing between two adjacent thermal fuses (11) in the same group of thermal fuses (11) is 4CM to 6CM.

9. A pipe system, characterized in that: A large HDPE pipe joint welding method according to any one of claims 1 to 8 is used for welding, comprising two HDPE pipes (100) and two welding strips (1), one welding strip (1) being welded to the inner wall of the joint of the two HDPE pipes (100), and the other welding strip (1) being welded to the outer wall of the joint of the two HDPE pipes (100), and the side of the welding strip (1) located inside the HDPE pipe (100) forming a fillet weld with the inner wall of the HDPE pipe (100).

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