Connecting structure for main pipe and branch pipe of framework type tower of wind generating set and construction method

Abstract

The invention discloses a main pipe and branch pipe connecting structure of a framework type tower of a wind generating set and a construction method. The main pipe and branch pipe connecting structure comprises a main pipe, a first pipe piece, a second pipe piece, a third pipe piece, a first branch pipe, an upper flange, a lower flange and a second branch pipe. During construction, the first pipe piece, the second pipe piece and the third pipe piece are welded in a factory, then the first pipe piece, the second pipe piece and the third pipe piece are welded to the main pipe, and then the first branch pipe is welded to the first pipe piece and the third pipe piece; and then welding between the upper flange and the first branch pipe and welding between the lower flange and the second branch pipe are completed, finally all components are transported to a site to be installed, and the upper flange and the lower flange are connected through a plurality of fasteners. Compared with the prior art, the method has the advantages of being small in steel consumption, excellent in fatigue resistance, convenient to construct, easy to maintain, high in adaptability and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of high-rise steel structure technology steel wind power tower, especially relates to a wind turbine generator system framework type tower main pipe and branch pipe connecting structure. BACKGROUND

[0002] With the large-scale of wind turbine generator and the continuous rise of the hub center height, the limit bending moment of the tower section exceeds 150000kNm, which becomes a common situation, and the traditional steel single pipe tower structure faces serious challenges. Due to the high and wide limit value of the land transportation conditions, the overall steel single pipe tower generally needs to be limited to below 4.8m in outer diameter, and the bending carrying capacity of the tower section can only be improved by increasing the wall thickness, which is relatively low in efficiency, resulting in a sharp rise in the amount of steel used for the tower section with the increase of the load, and poor economic efficiency.

[0003] The split steel single pipe tower can break through the limitation of the transportation conditions on the outer diameter of the tower section, improve the bending carrying capacity of the tower section by expanding the outer diameter, and has relatively high efficiency. However, the continuous increase of the outer diameter also leads to the increasingly prominent shortcoming of the tower section in resisting local buckling, and a large strength reduction coefficient is needed to maintain local stability, which reduces the utilization rate of steel strength. Moreover, the split steel single pipe tower has great difficulty in manufacturing and installation, and the cost per ton of the tower is much higher than that of the overall steel single pipe tower, so the economic efficiency is still not ideal.

[0004] For the combination of high tower and large wind turbine generator, the steel-concrete hybrid single pipe tower (hybrid tower) has better economic efficiency than the steel single pipe tower, but in practice, it is found that the prestressed reinforced concrete structure used for the tower of the wind turbine generator has many problems such as cracking and spalling, and the cost of tower maintenance and future demolition is high. Moreover, due to the large self-weight of the hybrid tower, the seismic response is very large, and the seismic performance becomes a difficult problem to overcome.

[0005] The single pipe tower is a cantilever beam structure, which can greatly improve the bending stiffness and capacity of the tower compared with the cantilever beam, cantilever truss or rigid frame, so in recent years, the framework type tower of the wind turbine generator (including space truss structure and rigid frame structure) has attracted more and more attention on land and sea, and the industry hopes that the emergence of new technology can solve the economic efficiency problem of the steel single pipe tower and the quality control problem of the hybrid tower. The main pipe and branch pipe connecting structure of the framework type tower of the wind turbine generator has a great influence on the economic efficiency and safety of the tower, and the intersecting welding joint can solve the problem of carrying capacity, but the stress distribution is complex, the local stress concentration coefficient is large, and the anti-fatigue performance of the single-sided welding seam has high discreteness, so enough safety redundancy is usually needed to ensure the safety of the joint, resulting in a large wall thickness of the joint area and high cost. SUMMARY

[0006] The wind turbine generator unit framework type tower main pipe and branch pipe connecting structure is mainly composed of a main pipe and a branch pipe, the main pipe and the branch pipe are connected through flanges and high-strength bolts, and vertical stiffening plates and annular stiffening plates are arranged in the main pipe.

[0007] In order to achieve the above object, the present application adopts the following technical scheme: A wind turbine generator unit framework type tower main pipe and branch pipe connecting structure, comprising a main pipe, a first pipe piece, a second pipe piece, a third pipe piece, a first branch pipe, an upper flange, a lower flange and a second branch pipe. The main pipe is connected with the first pipe piece, the second pipe piece and the third pipe piece in sequence from top to bottom through double-sided full penetration welds, one end of the first pipe piece, the second pipe piece and the third pipe piece is connected with the first branch pipe, the other end of the first pipe piece, the second pipe piece and the third pipe piece is connected with the first branch pipe, the first pipe piece and the third pipe piece are connected with the second pipe piece, the other end of the first branch pipe is connected with the upper flange, one end of the second branch pipe is connected with the lower flange, and the upper flange and the lower flange are connected together through a plurality of fasteners.

[0008] The main pipe is a steel circular pipe.

[0009] The first pipe piece and the third pipe piece are semicircular pipes, the planes where the first pipe piece, the third pipe piece and the first branch pipe intersect are toroidal surfaces, the first pipe piece and the third pipe piece each occupy half of the toroidal surface, and the axis of the tower drum, the axis of the first pipe piece and the axis of the third pipe piece are coplanar.

[0010] The second pipe piece is a flat plate and is parallel to the axis of the tower drum, and the second pipe piece is tangent to the first pipe piece and the third pipe piece.

[0011] The first pipe piece and the second pipe piece are connected through double-sided full penetration welds, and the second pipe piece and the third pipe piece are connected through double-sided full penetration welds.

[0012] The first branch pipe and the second branch pipe are steel circular pipes, and when the flange is an external flange, the length of the first branch pipe is not less than 300 mm.

[0013] The upper flange and the lower flange are T-shaped or L-shaped necked forged flanges, the upper flange is connected with the first branch pipe through double-sided full penetration butt welds, and the lower flange is connected with the second branch pipe through double-sided full penetration butt welds.

[0014] The further improvement of the present application is further comprising a vertical stiffener plate, the vertical stiffener plate is coplanar with the second pipe piece, the length of the vertical stiffener plate covers the intersection area of the main pipe and the first pipe piece, the second pipe piece and the third pipe piece, and the vertical stiffener plate is connected to the inner side of the main pipe through a double-sided full penetration welding seam.

[0015] The further improvement of the present application is further comprising a ring-shaped stiffener plate, the outer diameter of the ring-shaped stiffener plate is the same as the inner diameter of the main pipe, the axis of the ring-shaped stiffener plate is coincident with the axis of the main pipe, and the ring-shaped stiffener plate covers the intersection area of the second pipe piece and the main pipe.

[0016] The construction method of the framework tower main pipe and branch pipe connection structure of the wind turbine generator set comprises the following steps: The welding between the first pipe piece, the second pipe piece and the third pipe piece is completed in the factory, then the welding between the first pipe piece, the second pipe piece, the third pipe piece and the main pipe is completed, then the welding between the first branch pipe and the first pipe piece and the third pipe piece is completed, then the welding between the upper flange and the first branch pipe and the welding between the lower flange and the second branch pipe are completed, and finally all the components are transported to the site for installation, and the upper flange and the lower flange are connected through a plurality of fasteners.

[0017] Compared with the prior art, the present application has at least the following beneficial technical effects: The main pipe load of the present application is smoothly transmitted to the branch pipe through the vertical stiffener plate, the ring-shaped stiffener plate and the planar pipe piece, so that the stiffness changes gently, the stress distribution is uniform, and the stress concentration coefficient is small. This feature effectively avoids the structural damage caused by excessive local stress, prolongs the service life of the connection structure, and has higher stability and reliability under long-term complex load such as wind force compared with the traditional connection structure. Due to the uniform stress distribution, the possibility of fatigue crack initiation and propagation caused by stress concentration is reduced, thereby improving the fatigue resistance of the entire connection structure. This is crucial for wind turbine generators which are in a dynamic load environment for a long time, and can ensure that the unit maintains structural integrity during long-term operation, reducing maintenance costs and downtime caused by fatigue damage.

[0018] All the welding seams of the main pipe and branch pipe connection structure of the present application adopt double-sided full penetration butt welding seams, which can provide higher connection strength and reliability. Compared with other types of welding seams, the stress transmission of the double-sided full penetration butt welding seam is more uniform when bearing load, and cracks and other defects are not easy to occur. The welding seam can be internally (ultrasonic, X-ray) and externally (magnetic powder) inspected, which can comprehensively and accurately detect various defects inside and on the surface of the welding seam, such as pores, slag inclusions and cracks. Through strict detection means, the welding seam quality meets high standard requirements, making the fatigue resistance stable and reliable, reducing the risk of structural failure caused by welding seam quality problems during use, and improving the safety of the entire wind turbine generator set.

[0019] The main pipe and branch pipe connection structure of this invention has virtually no weak axes of resistance or stiffness. Provided the flange bolt prestress and flange thickness meet relevant requirements, a rigid connection between the main pipe and branch pipe can be achieved. This rigid connection more effectively transmits forces and moments, ensuring the integrity and stability of the structure, enabling the wind turbine generator to maintain a stable operating posture in complex wind environments. The design features of this connection structure make it highly suitable for spatial frame structures, meeting the stringent requirements of connection nodes in complex spatial structures like wind turbine generator towers. In spatial frame structures, forces and moments in various directions interact; a rigid connection better coordinates the forces between components, improving the overall load-bearing capacity and deformation resistance of the structure.

[0020] The thinner wall thickness of the node area effectively reduces material usage while ensuring structural strength and stability, thereby lowering manufacturing costs. Compared to traditional thick-walled node connection structures, this invention offers greater economic efficiency while meeting the same performance requirements, saving significant funds for the manufacturing and installation of wind turbine generators. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 An assembly drawing of a wind turbine generator frame tower main pipe and branch pipe connection structure; Figure 2 A front view of a wind turbine generator frame tower main pipe and branch pipe connection structure; Figure 3 A cross-sectional view (AA) of a wind turbine generator frame tower main pipe and branch pipe connection structure; Figure 4 This is a split diagram of the connection structure between the main pipe and branch pipes of a wind turbine generator frame tower.

[0023] In the attached image: 1. Main pipe, 2. First segment, 3. Second segment, 4. Third segment, 5. First branch pipe, 6. Upper flange, 7. Lower flange, 8. High-strength bolt, 9. Second branch pipe, 10. Vertical stiffening plate, 11. Annular stiffening plate. Detailed Implementation

[0024] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0025] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0027] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0028] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0029] It should be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0030] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0031] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0032] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0033] Example 1 like Figures 1 to 4 As shown, the present invention provides a main pipe and branch pipe connection structure for a wind turbine generator frame tower, including a main pipe 1, a first segment 2, a second segment 3, a third segment 4, a first branch pipe 5, an upper flange 6, a lower flange 7, and a second branch pipe 9. The main pipe 1 is connected to one end of the first segment 2, the second segment 3, and the third segment 4 sequentially from top to bottom via double-sided full penetration welds. The other ends of the first segment 2, the second segment 3, and the third segment 4 are all connected to one end of the first branch pipe 5, and the first segment 2 and the third segment 4 are respectively connected to the second segment 3. The other end of the first branch pipe 5 is connected to the upper flange 6, and one end of the second branch pipe 9 is connected to the lower flange 7. The upper flange 6 and the lower flange 7 are connected together by several fasteners.

[0034] In this embodiment, the fastener is a high-strength bolt 8.

[0035] In this embodiment, the main pipe 1 is a steel round pipe.

[0036] In this embodiment, the first tube segment 2 and the third tube segment 4 are semi-circular tubes, and the plane where the first tube segment 2, the third tube segment 4 and the first branch pipe 5 intersect is an annular surface, wherein the first tube segment 2 and the third tube segment 4 each occupy half of the annular surface, and the axis of the tower, the axis of the first tube segment 2 and the axis of the third tube segment 4 are coplanar.

[0037] In this embodiment, the second tube segment 3 is a flat plate and parallel to the axis of the tower, and the second tube segment 3 is tangent to both the first tube segment 2 and the third tube segment 4.

[0038] In this embodiment, the first segment 2 and the second segment 3, and the second segment 3 and the third segment 4 are connected by double-sided full penetration welds.

[0039] In this embodiment, the first branch pipe 5 and the second branch pipe 9 are steel round pipes. When the flange is an outer flange, the length of the first branch pipe 5 is not less than 300 mm.

[0040] In this embodiment, the upper flange 6 and the lower flange 7 are T-type or L-type necked forged flanges. The upper flange 6 is connected to the first branch pipe 5 by a double-sided full penetration butt weld, and the lower flange 7 is connected to the second branch pipe 9 by a double-sided full penetration butt weld.

[0041] In this embodiment, a vertical stiffening plate 10 is also included. The vertical stiffening plate 10 is coplanar with the second tube segment 3. The length of the vertical stiffening plate 10 covers the area where the main tube 1 intersects with the first tube segment 2, the second tube segment 3, and the third tube segment 4. The vertical stiffening plate 10 is connected to the inside of the main tube 1 by a double-sided full penetration weld.

[0042] In this embodiment, an annular stiffening plate 11 is also included. The outer diameter of the annular stiffening plate 11 is the same as the inner diameter of the main pipe 1, the axis of the annular stiffening plate 11 coincides with the axis of the main pipe 1, and the annular stiffening plate 11 covers the area where the second pipe segment 3 intersects with the main pipe 1.

[0043] Example 2 like Figures 1 to 4 As shown, the present invention provides a construction method for a connection structure between the main pipe and branch pipes of a wind turbine generator frame tower, comprising: Welding is completed at the factory between the first segment 2, the second segment 3, and the third segment 4. Then, welding is completed between the first segment 2, the second segment 3, and the third segment 4 and the main pipe 1. Next, welding is completed between the first branch pipe 5 and the first segment 2 and the third segment 4. Then, welding is completed between the upper flange 6 and the first branch pipe 5, and between the lower flange 7 and the second branch pipe 9. Finally, all components are transported to the site for installation. The upper flange 6 and the lower flange 7 are connected by several fasteners.

[0044] Example 3 like Figures 1 to 4 As shown, the present invention provides a construction method for a connection structure between the main pipe and branch pipes of a wind turbine generator frame tower, comprising: 1) Welding between the first segment 2, the second segment 3, and the third segment 4 is completed in the factory; 2) Complete the welding between the first segment 2, the second segment 3, the third segment 4 and the main pipe 1; 3) Complete the welding between the first branch pipe 5 and the first segment 2 and the third segment 3; 4) Complete the welding between the upper flange 6 and the first branch pipe 5; 5) Complete the welding between the lower flange 7 and the second branch pipe 9; 6) Transport all components to the site for installation, and connect the upper flange 6 and the lower flange 7 with high-strength bolts 8.

[0045] This invention utilizes a three-dimensional, split-type connection design of the first, second, and third segments to disperse the concentrated stress of traditional intersecting weld joints to multiple welding interfaces, significantly reducing the local stress concentration factor. The application of double-sided full-penetration welds further improves weld quality consistency, solves the technical challenge of high fatigue performance dispersion in single-sided welds, and extends the service life of the joint.

[0046] The modular segment structure of this invention allows for flexible adjustment of segment size and angle according to different wind turbine models (e.g., onshore / offshore, different power levels) without the need to redesign the main pipe-branch pipe connection system. This combination of standardization and modularity allows the same connection structure to adapt to various tower height and diameter requirements.

[0047] All welding processes are completed in the factory. Automated welding equipment enables 100% full penetration quality control of welds between segments and between segments and the main pipe, avoiding quality fluctuations caused by environmental factors during on-site welding. Non-destructive testing (such as ultrasonic testing) coverage in the factory environment reaches 100%, far exceeding on-site testing standards. On-site installation only requires connecting the upper and lower flanges with fasteners, reducing installation time by more than 60% compared to traditional intersecting weld joints.

[0048] The segmented pipe design eliminates the need for thick-walled pipe transitions at the connections between main and branch pipes. Finite element analysis has verified that this reduces steel consumption by 15%-20% under the same load conditions. The double-sided welded structure increases fatigue life to 2.3 times that of traditional joints (calculated according to DNVGL-RP-C203 standard), extending the maintenance cycle from 5 years to 12 years. The flange connection design allows for quick replacement of branch pipes, reducing single maintenance time from 72 hours to 8 hours and lowering operation and maintenance costs by over 70%.

[0049] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0050] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A structure for connecting a main pipe of a framework tower of a wind turbine generator system to a branch pipe, characterized in that, The main pipe (1), the first pipe piece (2), the second pipe piece (3), the third pipe piece (4), the first branch pipe (5), the upper flange (6), the lower flange (7) and the second branch pipe (9) are connected by double-sided full penetration welding. The main pipe (1) is connected with the first pipe piece (2), the second pipe piece (3) and the third pipe piece (4) in sequence from top to bottom by double-sided full penetration welding, the other ends of the first pipe piece (2), the second pipe piece (3) and the third pipe piece (4) are connected with one end of the first branch pipe (5), the first pipe piece (2) and the third pipe piece (4) are connected with the second pipe piece (3) respectively, the other end of the first branch pipe (5) is connected with the upper flange (6), one end of the second branch pipe (9) is connected with the lower flange (7), and the upper flange (6) and the lower flange (7) are connected together by a plurality of fasteners.

2. The wind turbine generator set frame-tower main pipe and branch pipe connection structure according to claim 1, characterized in that, The main pipe (1) is a steel pipe.

3. The wind turbine generator set frame-tower main pipe and branch pipe connection structure according to claim 1, characterized in that, The first pipe piece (2) and the third pipe piece (4) are semicircular pipes, the planes where the first pipe piece (2), the third pipe piece (4) and the first branch pipe (5) intersect are circular ring surfaces, the first pipe piece (2) and the third pipe piece (4) each occupy half of the circular ring, and the axis of the tower drum, the axis of the first pipe piece (2) and the axis of the third pipe piece (4) are coplanar.

4. The wind turbine generator set frame-tower main pipe and branch pipe connection structure according to claim 1, characterized in that, The second pipe piece (3) is a flat plate and is parallel to the axis of the tower drum, and the second pipe piece (3) is tangent to the first pipe piece (2) and the third pipe piece (4).

5. The wind turbine generator set frame-tower main pipe and branch pipe connection structure according to claim 1, characterized in that, The first pipe piece (2) and the second pipe piece (3), and the second pipe piece (3) and the third pipe piece (4) are connected by double-sided full penetration welding.

6. The wind turbine generator set frame-tower main pipe and branch pipe connection structure according to claim 1, characterized in that, The first branch pipe (5) and the second branch pipe (9) are steel pipes, and when the flange is an external flange, the length of the first branch pipe (5) is not less than 300 mm.

7. The wind turbine generator set frame-tower main pipe and branch pipe connection structure according to claim 1, characterized in that, The upper flange (6) and the lower flange (7) are T-shaped or L-shaped necked forged flanges, the upper flange (6) is connected with the first branch pipe (5) by double-sided full penetration butt welding, and the lower flange (7) is connected with the second branch pipe (9) by double-sided full penetration butt welding.

8. The wind turbine generator set frame-tower main pipe and branch pipe connection structure according to claim 1, characterized in that, A vertical stiffening plate (10) is further included, the vertical stiffening plate (10) is coplanar with the second pipe piece (3), the length of the vertical stiffening plate (10) covers the intersection area of the main pipe (1) and the first pipe piece (2), the second pipe piece (3) and the third pipe piece (4), and the vertical stiffening plate (10) is connected to the inner side of the main pipe (1) by double-sided full penetration welding.

9. The wind turbine generator set frame-tower main pipe and branch pipe connection structure according to claim 1, characterized in that, An annular stiffening plate (11) is further included, the outer diameter of the annular stiffening plate (11) is the same as the inner diameter of the main pipe (1), the axis of the annular stiffening plate (11) coincides with the axis of the main pipe (1), and the annular stiffening plate (11) covers the intersection area of the second pipe piece (3) and the main pipe (1).

10. The construction method of the wind turbine generator set framework tower main pipe and branch pipe connection structure according to any one of claims 1 to 9, characterized in that, The main pipe (1), the first pipe piece (2), the second pipe piece (3), the third pipe piece (4), the first branch pipe (5), the upper flange (6), the lower flange (7) and the second branch pipe (9) are connected by double-sided full penetration welding. The welding between the first pipe piece (2), the second pipe piece (3) and the third pipe piece (4) is completed in the factory, then the welding between the first pipe piece (2), the second pipe piece (3), the third pipe piece (4) and the main pipe (1) is completed, then the welding between the first branch pipe (5) and the first pipe piece (2), the third pipe piece (4) is completed, then the welding between the upper flange (6) and the first branch pipe (5) and the welding between the lower flange (7) and the second branch pipe (9) is completed, finally all the components are transported to the site for installation, and the upper flange (6) and the lower flange (7) are connected through a plurality of fasteners.

Images