Welding method for the assembly joint of offshore wind turbine jacket structure

Abstract

This application provides a welding method for the closure joint of an offshore wind turbine jacket assembly. The method involves moving an upper assembly component to align the upper and lower jacket legs, causing the annular gasket, annular assembly plate, and upper jacket leg to mate and form a welding bevel. The welding bevel is circumferentially divided into adjacent stress-relief areas and pre-welding areas. The projection of one stress-relief area lies within the area defined by two adjacent sets of tie rods. Spot welding is performed at least in the stress-relief areas to form an initial spot weld. At least one of the thickness and arc length of the initial spot weld is less than the predetermined final weld size for that area. After completing the initial spot weld, a first weld is formed before the pre-welding area, and a second weld is formed after the stress-relief area. The method provided by this application improves welding quality and efficiency, and eliminates the need for positioning auxiliary workpieces during the welding process.

Description

Technical Field

[0001] This invention relates to the technical field of welding of offshore wind power equipment, and specifically to a welding method for the closure joint of an offshore wind power jacket assembly. Background Technology

[0002] Offshore wind turbine jackets are foundation structures used to support offshore wind turbine generators. Their basic structure includes jacket legs, ducts, and braces. There are typically three or four jacket legs. The ducts are horizontal or near-horizontal steel pipes connecting the jacket legs to form a stable frame structure. The braces connect the jacket legs and the ducts with diagonal steel pipes to further enhance the structure's rigidity and stability. A transition section is usually installed at the top of the jacket to connect the jacket to the wind turbine generator. Pipe piles are typically connected to the bottom of the jacket legs, allowing them to be inserted into the seabed. Pipelines can be installed inside the jacket legs for use in the pile leg grouting connection process.

[0003] Currently, offshore wind turbine jackets are typically formed using vertical or horizontal welding methods, with direct welding between the jacket legs of the upper and lower assembly components. However, the welding quality of this direct-welded jacket assembly is currently unsatisfactory. Furthermore, vertical installations usually require crane lifting. Without positioning assistance, the crane may sway due to wind speed in the installation environment, leading to inaccurate alignment of the weld joints. Therefore, repeated alignment is required during welding, resulting in very low welding efficiency for vertical installations. Even when positioning assistance is used, the limited welding points prevent the selection of multiple welding points, further hindering welding efficiency. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a welding method for the assembly and closing joint of offshore wind turbine jacket, which is beneficial to improving welding quality and welding efficiency, and does not require the use of positioning auxiliary workpieces during the welding process.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0006] A welding method for the closure joint of an offshore wind turbine jacket assembly includes the following steps:

[0007] The lower assembly of the guide frame is erected at the welding station. The lower assembly includes tie rods and at least three lower guide legs arranged around it. Each pair of lower guide legs is connected by the tie rods. The top surface of each lower guide leg is connected to a steel annular assembly plate, which protrudes from the inner and outer tube surfaces of the lower guide leg.

[0008] The upper assembly of the guide frame is hoisted by a crane to the upper assembly of the lower assembly at the welding station. The upper assembly includes at least three upper guide legs arranged around and connected to each other. Each upper guide leg is welded with an annular gasket of steel placed in the tube cavity. The curved outer surface of the annular gasket is opposite to the inner tube surface of the upper guide leg, and the annular gasket protrudes from the bottom end of the upper guide leg.

[0009] The upper container is moved to align the upper guide leg and the lower guide leg, such that the annular gasket, the annular assembly plate, and the upper guide leg cooperate to form a welding bevel, and the curved outer surface of the annular assembly plate protrudes beyond the outer tube surface of the upper guide leg, the curved inner surface of the annular assembly plate protrudes beyond the curved inner surface of the annular gasket, and the curved outer surface of the annular gasket is exposed to the welding bevel. The welding bevel is divided circumferentially into adjacent stress relief areas and pre-welding areas. When viewed circumferentially along the lower guide leg, the projection of one of the stress relief areas is located within the area defined by two adjacent sets of tie rods.

[0010] Spot welding is performed at least in the stress relief area to form an initial spot weld, wherein at least one of the thickness and arc length of the initial spot weld is less than the preset final weld size in that area.

[0011] After the initial spot weld is completed, a first weld is formed in the pre-welded area, and then a second weld is formed in the stress-relief area. The first weld and the second weld together form the final assembly weld.

[0012] In some possible implementations, each of the weld bevels has at least four stress relief regions, spaced apart from each adjacent pair of stress relief regions. When viewed circumferentially along the lower guide leg, the projections of a portion of the stress relief regions are located outside the areas defined by two adjacent sets of tie rods, the projection of the remaining stress relief region is located within one set of tie rods, and the projection of the remaining stress relief region is located within another adjacent set of tie rods.

[0013] In some possible implementations, forming the initial spot weld includes:

[0014] Ensure that the welding strength of the multiple initial spot welds is sufficient to support the upper and lower container components detached from the crane;

[0015] After forming multiple initial spot welds, the crane is removed.

[0016] In some possible implementations, the step of forming the first weld includes:

[0017] First, form an initial weld of at least one-third the thickness of the weld in the current area, and then remove the crane;

[0018] After the crane is removed, a residual weld of the remaining weld thickness in the current area is formed, thereby forming the first weld.

[0019] In some possible implementations, the step of forming the first weld seam further includes:

[0020] Cool the initial weld to room temperature;

[0021] The crane is removed only after the cooled initial weld seam has been inspected and found to be qualified.

[0022] The initial weld is then preheated to at least 110°C to form the remaining weld thickness in the current area.

[0023] The remaining weld seam is subjected to repeated cooling and testing steps. After passing the test, it is left to stand at room temperature for at least 48 hours before the final test. If the final test is passed, the first weld seam is completed.

[0024] In some possible implementations, the step of forming the second weld includes:

[0025] Form an initial weld with a thickness of at least one-third of the current weld thickness in the current area;

[0026] Cool the initial weld to room temperature;

[0027] After inspecting the cooled initial weld seam for defects, the initial weld seam is preheated to at least 110°C, and then the remaining weld seam thickness in the current area is formed.

[0028] The remaining weld seam is subjected to repeated cooling and testing steps. After passing the test, it is left to stand at room temperature for at least 48 hours before the final test. If the final test is passed, the second weld seam is completed.

[0029] In some possible implementations, in forming the first weld and the second weld, both the initial weld and the remaining weld are cooled to room temperature by wrapping them with insulating cotton and then allowing them to cool naturally.

[0030] In some possible implementations, when viewed axially along the upper guide leg, both the annular gasket and the lower end face of the upper guide leg are inclined surfaces. When viewed radially from the outside of the upper guide leg towards the inside of the tube, the inclined surfaces slope downwards and forwards. The lower end face of the upper guide leg and the inner tube surface are connected by an arc transition to form a first rounded corner with a downward bow. The lower end face of the annular gasket and the curved inner surface are connected by an arc transition to form a second rounded corner with a downward bow. The annular gasket is welded to the first rounded corner. When the weld bevel is formed, the first rounded corner and the second rounded corner are exposed in the weld bevel.

[0031] In some possible implementations, the gap between the curved outer surface of the annular gasket and the inner tube surface of the upper guide leg is less than or equal to 1 mm. When forming the welding bevel, the first fillet and the first pair of root gaps formed by the annular assembly plate are less than or equal to 10 mm, and the second fillet and the second pair of root gaps formed by the annular assembly plate are less than or equal to 3 mm.

[0032] In some possible implementations, the lower side of the annular assembly plate has a first support seat protruding from the outer tube surface of the lower guide leg. When viewed circumferentially along the lower guide leg, the first support seat is located outside the area defined by the two adjacent sets of tie rods. A jack is installed on the first support seat. A second support seat protrudes from the outer tube surface of the upper guide leg. A first hydraulic line is provided in the cavity of the lower guide leg, and a second hydraulic line is provided in the cavity of the upper guide leg.

[0033] The steps for forming the weld bevel include:

[0034] The jack is used to first support the upper and lower assembly components to form an operating gap larger than the welding gap, and then the first hydraulic line and the second hydraulic line are connected from the operating gap to form a hydraulic line assembly.

[0035] After the hydraulic pipeline assembly passes the test, a fireproof layer is wrapped around the pipeline connection. After wrapping, a heat insulation component is used to separate the portion of the hydraulic pipeline assembly near the operating gap from the lower guide leg and the upper guide leg.

[0036] After the hydraulic pipeline assembly is disassembled, the jack is lowered, causing the operating gap to shrink and become the welding gap. Then, the upper guide leg and the lower guide leg are aligned, and all supporting structures are removed to obtain the welding bevel.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] In this application, the welding bevel shape is adjusted by introducing additional assembly plates, gaskets, and guide legs. Furthermore, compared to welding bevels formed by direct butt joints between the upper and lower guide legs, the welding bevel provided in this application improves both solder capacity and heat dissipation during welding, avoiding adverse effects caused by thermal stress. Additionally, the arrangement of stress relief zones and pre-welding zones, employing a welding method that first performs spot welding at least in the stress relief zone, then forms the first weld in the pre-welding zone, and finally forms the second weld in the stress relief zone, eliminates the need for positioning auxiliary workpieces during welding. This solves the problem of limited welding sites, improving welding efficiency. Moreover, this method facilitates welding stress relief, thereby improving welding quality.

[0039] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of a crane lifting an upper container component to a position above a lower container component at a welding station, according to one embodiment of this application.

[0041] Figure 2 This is a schematic diagram showing the connection between the lower guide leg, the annular assembly plate, and the tie rod.

[0042] Figure 3 This is a simplified diagram showing the arrangement of the stress relief area (red part) and the pre-welded area (blue part) in a partial cross-section of the lower container component;

[0043] Figure 4 A simplified diagram showing the stress relief area (blank area), the pre-welded area, and the initial spot weld (the darker part in the blank area);

[0044] Figure 5 A schematic diagram of the cross-section of the formed weld bevel;

[0045] Figure 6 This is a structural diagram illustrating the process of connecting hydraulic pipelines.

[0046] Explanation of icon numbers:

[0047] 10-Crane; 20-Lower container component; 21-Lower guide leg; 23-Annular assembly plate; 231-Bent inner surface of the annular assembly plate; 232-Bent outer surface of the annular assembly plate; 24-First support seat; 25-Jack; 27-Tie rod; 28-Arrangement; 201-Stress relief area; 202-Pre-welded area; 203-Spot weld initial weld; 30-Upper container component; 31-Upper guide leg; 311-Inner tube surface of the upper guide leg; 312-Outer tube surface of the upper guide leg; 313-Lower end face of the upper guide leg; 310- First fillet; 33-Annular gasket; 331-Bent inner surface of annular gasket; 332-Bent outer surface of annular gasket; 333-Lower end face of annular gasket; 330-Second fillet; 36-Second support; 37-Diagonal brace; 41-First weld bead; 42-Second weld bead; 43-Third weld bead; 44-Fourth weld bead; 45-Fifth weld bead; 46-Sixth weld bead; 47-Seventh weld bead; 48-Eighth weld bead; 49-Ninth weld bead; 60-Hydraulic pipeline assembly; 61-First hydraulic pipeline; 62-Second hydraulic pipeline. Detailed Implementation

[0048] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0050] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are constructed to distinguish different objects, not to describe a particular order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. It should be noted that when an element is referred to as "fixed to" or "connected to" another element, it may be directly on the other element or there may be an intervening element. When an element is referred to as "connected to" another element, it may be directly connected to the other element or there may be an intervening element. The accompanying drawings only depict the stacking relationship between different layers and do not limit their thickness relationships.

[0051] The following describes some embodiments of the present invention in detail. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0052] One embodiment of this application provides a welding method for the assembly and closing joint of an offshore wind turbine jacket, comprising the following steps.

[0053] Reference Figure 1 Step 1: Erect the lower assembly 20 of the guide frame assembly at the welding station. The lower assembly 20 includes tie rods 27 and at least three lower guide legs 21 arranged in a triangular pattern (shown in the figure). Each pair of lower guide legs 21 is connected by tie rods 27. The tie rods can be inclined or horizontal. Multiple tie rods 27 located between each pair of lower guide legs 21 can form a cross structure, with the tie rods 27 of the previous cross structure spaced apart from those of the subsequent cross structure. For example, the lower guide legs 21 and tie rods 27 can be connected by welding. (Refer to reference...) Figure 2Each lower guide leg 21 has a steel annular mounting plate 23 connected to its top surface. The annular mounting plate 23 protrudes from the inner and outer tube surfaces of the lower guide leg 21; that is, the curved inner surface 231 of the annular mounting plate protrudes from the inner tube surface of the lower guide leg 21, and the curved outer surface 232 of the annular mounting plate protrudes from the outer tube surface of the lower guide leg 21. The annular mounting plate 23 and the lower guide leg 21 can be connected by means including but not limited to welding or integral molding. For example, the material of the mounting plate can be EN 10025-3S355NL-Z35.

[0054] In some embodiments, in conjunction with reference Figure 6 The lower side of the annular assembly plate 23 has a first support seat 24 protruding from the outer tube surface of the lower guide leg 21. Viewed circumferentially along the lower guide leg 21, the first support seat 24 is located outside the area defined by two adjacent sets of tie rods 27. A jack 25 is mounted on the first support seat 24. For example, the mounting base of the jack 25 can be installed on the top surface of the first support seat 24 by welding with a stack 28. The stack 28 can be a square structure, and two adjacent end faces of the stack 28 can be welded to the first support seat 24 and the jack 25 respectively. For example, the first support seat 24 and the jack 25 can be installed first and then erected together with the lower guide leg 21, which improves operational convenience and safety. Alternatively, the lower guide leg 21 can be erected first, and then the first support seat 24 and the jack 25 can be installed. For example, the first support seat 24 can be fixed to the outer tube surface of the lower guide leg 21 by welding. A first hydraulic line 61 is provided inside the cavity of the lower guide leg 21. In this application, the first support 24 and the jack 25 are provided mainly for the installation of hydraulic pipelines.

[0055] For example, the lower assembly 20 can be erected at the welding station by a crane 10.

[0056] Step 2: Using crane 10, the upper assembly 30 of the guide frame assembly is lifted above the lower assembly 20 at the welding station. The upper assembly 30 includes at least three upper guide legs 31 arranged in a triangular pattern and connected to each other (the figure shows three upper guide legs 31 arranged in a triangular pattern; for example, adjacent upper guide legs 31 can be connected by diagonal braces 37, and the diagonal braces 37 and the upper guide legs 31 can be fixed by welding). Refer to the reference... Figure 5Each upper guide leg 31 is welded with an annular steel gasket 33 placed inside the tube cavity. For example, the gasket can be made of S355J2+N material, and for example, the gasket wall thickness is 6mm. The curved outer surface 332 of the annular gasket is opposite to the inner tube surface 311 of the upper guide leg, and the annular gasket 33 protrudes from the bottom end of the upper guide leg 31. For example, the upper guide leg 31 and the lower guide leg 21 can have the same dimensions; for example, the outer diameter can be 1630mm and the wall thickness can be 90mm. For example, a 4000T crane 10 can be used for hoisting. For example, the material of both the lower guide leg 21 and the upper guide leg 31 can include steel.

[0057] In some embodiments, in conjunction with reference Figure 6 The outer tube surface 312 of the upper guide leg is provided with a second support seat 36. For example, the second support seat 36 can be fixed to the outer tube surface 312 of the upper guide leg by welding. A second hydraulic line 62 is provided inside the cavity of the upper guide leg 31.

[0058] In some embodiments, refer to Figure 5 Viewed axially along the upper guide leg 31, the lower end face 333 of the annular gasket is inclined, and the lower end face 313 of the upper guide leg is also inclined. Viewed radially from the outside of the upper guide leg 31 towards the inside, the inclined surfaces slope downwards and forwards. The lower end face 313 of the upper guide leg and the inner tube surface 311 of the upper guide leg are connected by an arc-shaped transition to form a downward-curving first fillet 310. The lower end face 333 of the annular gasket and the curved inner surface 331 of the annular gasket are connected by an arc-shaped transition to form a downward-curving second fillet 330. The annular gasket 33 is welded to the first fillet 310. The first fillet 310 and the second fillet 330 can avoid stress concentration, thus further improving the subsequent welding quality. The inclined surfaces are beneficial for increasing the solder capacity and heat dissipation, thus further improving the welding quality.

[0059] In some embodiments, the inclination angle of the slope can be selected as 45 degrees.

[0060] In some embodiments, the radius of the first fillet 310 is R2-R5mm.

[0061] In some embodiments, the gap between the curved outer surface 332 of the annular gasket and the inner tube surface 311 of the upper guide leg is less than or equal to 1 mm, which helps to ensure that the annular gasket 33 and the upper guide leg 31 fit tightly, thereby further improving the subsequent welding quality.

[0062] Step 3: Move the upper container component 30 to align the upper guide leg 31 and the lower guide leg 21, so that the annular gasket 33, the annular assembly plate 23, and the upper guide leg 31 cooperate to form a welding bevel, and the curved outer surface 232 of the annular assembly plate also protrudes beyond the outer tube surface 312 of the upper guide leg, the curved inner surface 231 of the annular assembly plate also protrudes beyond the curved inner surface 331 of the annular gasket, and the curved outer surface 332 of the annular gasket is exposed at the welding bevel, as shown in the reference. Figures 3 to 5 The weld bevel is divided into adjacent stress relief areas 201 and pre-welded areas 202 along the circumference. When viewed along the circumference of the lower guide leg 21, the projection of a stress relief area 201 is located within the area defined by two adjacent sets of tie rods 27.

[0063] In some embodiments, refer to Figure 3 and Figure 4 In each weld bevel, there are at least four stress relief regions 201 (six stress relief regions 201 are shown in the figure). These regions are spaced apart from each other. Viewed circumferentially along the lower guide leg 21, the projections of a portion of the stress relief regions 201 fall outside the areas defined by two adjacent sets of tie rods 27 (three stress relief regions 201 in the figure are outside the areas defined by two sets of tie rods 27), the projection of one stress relief region 201 falls within one set of tie rods 27, and the projection of the remaining stress relief region 201 falls within another adjacent set of tie rods 27. Arranging multiple stress relief regions 201 facilitates more effective stress release during welding and allows for the placement of more spot welds later, thereby improving initial positioning stability. For example, the arc length between each pair of adjacent stress relief regions 201 can be the same or different.

[0064] For example, the number of stress relief regions 201 in each weld bevel can be six or eight, but is not limited to this. The number of stress relief regions 201 can be determined based on the weight of the upper container 30 and the lower container 20 and the welding strength.

[0065] In some embodiments, the step of forming a welding bevel includes: using a jack 25 to first support the upper assembly 30 and the lower assembly 20 to form an operating gap larger than the welding gap. For example, the adjustment standard for the operating gap can be that the upper guide leg 31 is raised 450mm relative to the lower guide leg 21, and the width of the gap can be adjusted according to actual needs and ease of operation. Then, the first hydraulic line 61 and the second hydraulic line 62 are connected from the operating gap to form a hydraulic line assembly 60. After the hydraulic line assembly 60 passes the test, a fireproof layer (not shown) is wrapped around the line connections. For example, the fireproof layer material can be one of aluminum silicate fiber, high-silica expanded glass fiber, or composite base fabric fireproof cotton. After wrapping, a heat-insulating component is used to separate the lower guide leg 21 and the upper guide leg 31 from the portion of the hydraulic pipeline assembly 60 near the operating gap. After separating the hydraulic pipeline assembly 60, the jack 25 is lowered, causing the operating gap to narrow and become a welding gap. Then, the upper guide leg 31 and the lower guide leg 21 are aligned, and all supporting structures (such as the jack 25, the first support seat 24, and the second support seat 36) are removed to obtain a welding bevel. For example, the heat-insulating component may include, but is not limited to, a vacuum heat insulation board or a polyurethane heat insulation board. For example, the fireproof layer may extend into the cavity of the upper guide leg 31. For example, when the upper guide leg 31 is raised 450mm relative to the lower guide leg 21, the fireproof layer may be wrapped upwards for a distance of 500mm. The fireproof layer can prevent damage to the hydraulic pipeline during subsequent welding. Using jack 25 and supporting structures to assist in the assembly of hydraulic pipelines improves ease of operation. Furthermore, during the assembly process, the support structures such as jack 25 also help improve assembly accuracy and ease of operation.

[0066] In another embodiment, when welding of hydraulic lines is not required, the jack 25, the first support 24 and the second support 36 can be omitted, and the upper guide leg 31 and the lower guide leg 21 can be directly aligned to form a welding bevel.

[0067] In some embodiments, when forming the welding bevel, the first set of root gaps L1 formed by the first fillet 310 and the annular assembly plate 23 is less than or equal to 10 mm, and the second set of root gaps L2 formed by the second fillet 330 and the annular assembly plate 23 is less than or equal to 3 mm. The fit between the root gaps and the fit of the welding bevel are used to limit the weld size and shape, thereby facilitating the control of the weld quality.

[0068] In some embodiments, when forming the weld bevel, the first fillet 310 and the second fillet 330 are exposed at the weld bevel.

[0069] Step 4: Perform spot welding at least in the stress relief area 201 to form an initial spot weld 203. At least one of the thickness and arc length of the initial spot weld 203 is less than the preset final weld size for that area (refer to...). Figure 4 That is, the stress relief region 201 can be located in the pre-welded region 202, or it can be not located in the pre-welded region 202. Taking the stress relief region 201 as an example, the thickness of the initial spot weld 203 formed can be less than the preset final weld thickness of the stress relief region 201, or the arc length of the initial spot weld 203 formed can be less than the preset final weld arc length of the stress relief region 201 (e.g., Figure 4 (as shown), or, the arc length and thickness of the initial spot weld 203 formed can both be smaller than the preset final weld arc length and thickness of the stress release area 201.

[0070] In some embodiments, forming the initial spot welds 203 includes: ensuring that the welding strength of the multiple initial spot welds 203 is sufficient to support the upper container component 30 and the lower container component 20 detached from the crane 10; and removing the crane 10 after forming the multiple initial spot welds 203. For example, the welding strength can be calculated based on the weight and dimensions of the lower container component 20 and the upper container component 30 to set at least one of the number, arc length, spacing, and thickness of the initial spot welds 203, ensuring that the multiple initial spot welds 203 can support the upper container component 30 and the lower container component 20 detached from the crane. For example, the minimum number of spot welds can be eight, where five segments have a minimum length of 200 mm and a weld spacing of 585 mm, and the other three segments have a minimum length of 300 mm and a weld spacing of 260 mm, with a minimum spot weld thickness of 40 mm. For example, the minimum number of spot welds can be 6, the minimum length of each spot weld segment can be 395mm, and the minimum thickness of the spot weld seam can be 30mm. There are multiple ways to ensure that the weld strength after detachment from crane 10 meets the requirements. Crane 10 can be detached after the initial spot weld seam 203 is completed, which allows crane 10 to be quickly put into welding work for another offshore wind turbine jacket assembly, thereby improving the efficiency of equipment use and further improving the welding efficiency of multiple batches of assembly.

[0071] In another embodiment, the crane 10 can still maintain its lifting function after the initial spot weld 203 is completed. Correspondingly, the number of stress relief areas 201 can be reduced, and the number or size of the initial spot weld 203 can be reduced.

[0072] Step 5: After completing the initial spot weld 203, the first weld is formed in the pre-welded area 202, and then the second weld is formed in the stress release area 201. The first weld and the second weld together form the final assembly weld.

[0073] In some embodiments, the step of forming the first weld includes: first forming an initial weld of at least one-third the weld thickness in the current area, then removing the crane 10, and after removing the crane 10, forming a residual weld of the remaining weld thickness in the current area, thereby forming the first weld. That is, removing the crane 10 before forming the first weld is more conducive to ensuring the stability of the welding, and also improves the utilization efficiency of the crane 10 compared to the approach of removing the crane 10 after completing the first weld.

[0074] In some embodiments, the step of forming the first weld further includes: cooling the initial weld to room temperature, inspecting the cooled initial weld for compliance before removing the crane 10, then preheating the initial weld to at least 110°C to form a residual weld of the remaining weld thickness in the current area, repeating the cooling and inspection steps for the residual weld sequentially, and after passing the inspection, continuing to place it at room temperature for at least 48 hours before performing a final inspection. Passing the final inspection completes the first weld. Stricter inspection standards help reduce false positives in quality inspection, thereby ensuring the final welding quality. For example, the inspection of the initial weld and the residual weld can be UT inspection (ultrasonic non-destructive testing).

[0075] In some embodiments, during the formation of the first weld, both the initial weld and the remaining weld are cooled to room temperature by wrapping them with insulating cotton and then allowing them to cool naturally. For example, the insulating cotton can be made of aluminum silicate fiber, high-silica expanded glass fiber, or composite fire-resistant cotton. Using insulating cotton for cooling avoids a large temperature difference between the weld and the outdoor environment, thus helping to prevent cracking caused by thermal stress and further improving welding quality.

[0076] In some embodiments, the second weld formation step includes: forming an initial weld of at least one-third weld thickness in the current area; cooling the initial weld to room temperature; inspecting the cooled initial weld for compliance; preheating the initial weld to at least 110°C; then forming a residual weld of the remaining weld thickness in the current area; repeating the cooling and inspection steps for the residual weld; after passing the inspection, allowing it to remain at room temperature for at least 48 hours before a final inspection; if the final inspection passes, the second weld is complete. Similarly, the operation steps for the second weld can further improve the weld quality. For example, the inspection of the initial weld and the residual weld can be UT inspection (ultrasonic non-destructive testing).

[0077] In some embodiments, during the step of forming the second weld, both the initial weld and the residual weld are cooled to room temperature by wrapping them with insulating cotton and then allowing them to cool naturally. For example, the insulating cotton can be made of aluminum silicate fiber, high-silica expanded glass fiber, or composite fire-resistant cotton. Using insulating cotton for cooling avoids a large temperature difference between the weld and the outdoor environment, thus helping to prevent cracking caused by thermal stress and further improving weld quality.

[0078] In the welding processes described above, flux-cored wire gas shielded welding (FCAW-G) can be used. Welding procedure qualification (PQR) and welding procedure specification (WPS) should be completed according to the project specifications and DNV-OS-C401-2023 standard. After approval by the owner, the approved WPS should be used for welding operations. During the process, the preheating requirements and welding process parameters of the WPS must be strictly followed.

[0079] For example, the welding in the above steps can be arranged as follows: For example, first weld the annular gasket 33 and the annular assembly plate 23 to form a first weld bead 41, then weld the first weld bead 41 and the adjacent upper guide leg 31 to form a second weld bead 42, the solder of the second weld bead 42 filling the space enclosed by the annular gasket 33 and the first fillet 310, then weld the second weld bead 42 and a portion of the adjacent upper guide leg 31 to form a third weld bead 43, then weld the third weld bead 43 and a portion of the adjacent annular assembly plate 23 to form a fourth weld bead 44, and then weld the fourth weld bead 44 and the adjacent annular assembly plate 23... The fifth weld bead 45 is formed by welding the third weld bead 43 and the fifth weld bead 45 to form the sixth weld bead 46. The sixth weld bead 46 and the adjacent upper guide leg 31 are then welded to form the seventh weld bead 47. The sixth weld bead 46 and the adjacent annular assembly plate 23 are then welded to form the eighth weld bead 48. The seventh weld bead 47 and the eighth weld bead 48 are then welded to form the ninth weld bead 49. The welding sequence and welding method of the seventh weld bead 47, the eighth weld bead 48 and the ninth weld bead 49 are then repeated to form subsequent weld beads.

[0080] In this application, the welding bevel shape is adjusted by introducing additional assembly plates, gaskets, and guide legs. Furthermore, compared to the welding bevel formed by the direct butt joint of the upper guide leg 31 and the lower guide leg 21, the welding bevel provided in this application is beneficial in two ways: firstly, it increases the solder capacity; secondly, it improves heat dissipation during welding, avoiding adverse effects caused by thermal stress. Additionally, the arrangement of the stress relief area 201 and the pre-welding area 202, and the welding method of first spot welding at least in the stress relief area 201, then forming the first weld in the pre-welding area 202, and finally forming the second weld in the stress relief area 201, eliminates the need for positioning auxiliary workpieces during the welding process. This solves the problem of limited welding points, thereby improving welding efficiency. Moreover, the above method facilitates welding stress relief, thus improving welding quality.

[0081] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A welding method for the closure joint of an offshore wind turbine jacket assembly, characterized in that, Includes the following steps: The lower assembly of the guide frame is erected at the welding station. The lower assembly includes tie rods and at least three lower guide legs arranged around it. Each pair of lower guide legs is connected by the tie rods. The top surface of each lower guide leg is connected to a steel annular assembly plate, which protrudes from the inner and outer tube surfaces of the lower guide leg. The upper assembly of the guide frame is hoisted by a crane to the upper assembly of the lower assembly at the welding station. The upper assembly includes at least three upper guide legs arranged around and connected to each other. Each upper guide leg is welded with an annular gasket of steel placed in the tube cavity. The curved outer surface of the annular gasket is opposite to the inner tube surface of the upper guide leg, and the annular gasket protrudes from the bottom end of the upper guide leg. The upper container is moved to align the upper guide leg and the lower guide leg, such that the annular gasket, the annular assembly plate, and the upper guide leg cooperate to form a welding bevel, and the curved outer surface of the annular assembly plate protrudes beyond the outer tube surface of the upper guide leg, the curved inner surface of the annular assembly plate protrudes beyond the curved inner surface of the annular gasket, and the curved outer surface of the annular gasket is exposed to the welding bevel. The welding bevel is divided circumferentially into adjacent stress relief areas and pre-welding areas. When viewed circumferentially along the lower guide leg, the projection of one of the stress relief areas is located within the area defined by two adjacent sets of tie rods. Spot welding is performed at least in the stress relief area to form an initial spot weld, wherein at least one of the thickness and arc length of the initial spot weld is less than the preset final weld size in that area. After the initial spot weld is completed, a first weld is formed in the pre-welded area, and then a second weld is formed in the stress-relief area. The first weld and the second weld together form the final assembly weld.

2. The welding method as described in claim 1, characterized in that, In each of the weld bevels, the number of stress relief areas is at least four, and each pair of adjacent stress relief areas is spaced apart. When viewed circumferentially along the lower guide leg, the projections of a portion of the stress relief areas are located outside the areas defined by two adjacent sets of tie rods, the projection of one stress relief area is located within one set of tie rods, and the projection of the remaining stress relief area is located within another adjacent set of tie rods.

3. The welding method as described in claim 2, characterized in that, The formation of the initial spot weld includes: Ensure that the welding strength of the multiple initial spot welds is sufficient to support the upper and lower container components after they have detached from the crane; After forming multiple initial spot welds, the crane is removed.

4. The welding method as described in claim 2, characterized in that, The steps for forming the first weld include: First, form an initial weld of at least one-third the thickness of the weld in the current area, and then remove the crane; After the crane is removed, a residual weld of the remaining weld thickness in the current area is formed, thereby forming the first weld.

5. The welding method as described in claim 4, characterized in that, The steps for forming the first weld also include: Cool the initial weld to room temperature; The crane is removed only after the cooled initial weld seam has been inspected and found to be qualified. The initial weld is then preheated to at least 110°C to form the remaining weld thickness in the current area. The remaining weld seam is subjected to repeated cooling and testing steps. After passing the test, it is left to stand at room temperature for at least 48 hours before the final test. If the final test is passed, the first weld seam is completed.

6. The welding method as described in claim 5, characterized in that, The steps for forming the second weld include: Form an initial weld with a thickness of at least one-third of the current weld thickness in the current area; Cool the initial weld to room temperature; After inspecting the cooled initial weld seam for defects, the initial weld seam is preheated to at least 110°C, and then the remaining weld seam thickness in the current area is formed. The remaining weld seam is subjected to repeated cooling and testing steps. After passing the test, it is left to stand at room temperature for at least 48 hours before the final test. If the final test is passed, the second weld seam is completed.

7. The welding method as described in claim 6, characterized in that, In forming the first weld and the second weld, both the initial weld and the remaining weld are cooled to room temperature by wrapping them with insulating cotton and then allowing them to cool naturally.

8. The welding method as described in claim 1, characterized in that, Viewed axially along the upper guide leg, both the annular gasket and the lower end face of the upper guide leg are inclined surfaces. Viewed radially from the outside of the upper guide leg towards the inside of the tube, the inclined surfaces slope downwards and forwards. The lower end face of the upper guide leg and the inner tube surface are connected by an arc transition to form a first rounded corner with the bow pointing downwards. The lower end face of the annular gasket and the curved inner surface are connected by an arc transition to form a second rounded corner with the bow pointing downwards. The annular gasket is welded to the first rounded corner. When the welding bevel is formed, the first rounded corner and the second rounded corner are exposed in the welding bevel.

9. The welding method as described in claim 8, characterized in that, The gap between the curved outer surface of the annular gasket and the inner tube surface of the upper guide leg is less than or equal to 1 mm. When forming the welding bevel, the first fillet and the first pair of root gaps formed by the annular assembly plate are less than or equal to 10 mm, and the second fillet and the second pair of root gaps formed by the annular assembly plate are less than or equal to 3 mm.

10. The welding method as described in claim 1, characterized in that, The lower side of the annular assembly plate has a first support seat protruding from the outer tube surface of the lower guide leg. When viewed along the circumference of the lower guide leg, the first support seat is located outside the area defined by the two adjacent sets of tie rods. A jack is installed on the first support seat. A second support seat protrudes from the outer tube surface of the upper guide leg. A first hydraulic line is provided in the tube cavity of the lower guide leg, and a second hydraulic line is provided in the tube cavity of the upper guide leg. The steps for forming the weld bevel include: The jack is used to first support the upper and lower assembly components to form an operating gap larger than the welding gap, and then the first hydraulic line and the second hydraulic line are connected from the operating gap to form a hydraulic line assembly. After the hydraulic pipeline assembly passes the test, a fireproof layer is wrapped around the pipeline connection. After wrapping, a heat insulation component is used to separate the portion of the hydraulic pipeline assembly near the operating gap from the lower guide leg and the upper guide leg. After the hydraulic pipeline assembly is disassembled, the jack is lowered, causing the operating gap to shrink and become the welding gap. Then, the upper guide leg and the lower guide leg are aligned, and all supporting structures are removed to obtain the welding bevel.

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