Integrated installation method for large mast

Abstract

The present invention discloses an integrated installation method for a large mast, comprising the following steps: (1) installing the bottom mast and the hull structure in an integrated manner; (2) making the platform, the outfitting base and the cable bridge in an integrated manner with the mast body; (3) after determining the BASE surface of the mast body, horizontally placing the mast body in a shipyard by means of a jig; (4) arranging an upper lifting lug, a middle lifting lug and a lower lifting lug on the outside of the mast body; (5) installing equipment that does not interfere with the lifting; (6) lifting the mast body in an integrated manner, moving it horizontally to a designated position above the dock, and then flipping the mast from a horizontal state to a vertical state and installing it; (7) installing the railing of the upper platform and then installing the valuable equipment; (8) installing the internal equipment of the mast body; and (9) cutting off the lifting lug. The present invention solves the problem of multiple lifting of large masts and improves the convenience of on-site construction.

Description

Technical Field

[0001] The invention relates to the technical field of ship mast construction, and in particular to an integrated installation method for a large mast. Background Art

[0002] Because containers or other components are stacked on the upper part of the main deck of large ships, masts are installed to reduce blind spots and facilitate personnel to observe changes in signal light information in the cab. However, for large masts such as foremast, considering the raw materials and manufacturing process, each section of the main mast is spliced ​​with rolled plates, and then the two sections of the main mast are butt-welded and installed. The welding work is extremely difficult, and it is difficult to ensure the straightness of the mast. It also requires multiple hoisting, which is time-consuming and labor-intensive. In addition, the installation and layout of outfitting parts and equipment are relatively complicated, which increases the difficulty of high-altitude operations and also brings safety hazards. Therefore, the above problems need to be solved urgently. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide an integrated installation method for a large mast, which has reasonable design and is convenient for on-site implementation, solves the problem of multiple hoisting of a large mast, and greatly improves the convenience of on-site construction.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solution: An integrated installation method of a large mast of the present invention has the following innovative features:

[0005] (1) The bottom mast between the bow main deck and the second deck is installed in an integrated manner with the hull structure, and a sample punch mark is provided at the butt joint of the bottom mast;

[0006] (2) The platform, outfitting base and cable tray that do not interfere with the lifting are made into an integrated unit with the mast body, and a sample punch mark is set at the joint of the mast body. The handrail on the upper platform that interferes with the lifting is designed to be detachable;

[0007] (3) After determining the reference plane of the mast body, place the mast body horizontally in the shipyard using a jig;

[0008] In the above steps, according to the different centers of gravity of the mast body when it is laid flat in different directions, combined with the shape of the mast body and the position of the platform, the most suitable side for landing is determined as the reference surface of the mast body;

[0009] In the above steps, a number of jigs are arranged in sequence along the length direction of the reference surface of the mast body, and each of the jigs is composed of a jig body and a wooden block; each of the jig bodies is welded and spliced ​​by channel steel, and a wooden block is padded between its upper end and the reference surface of the mast body, and a semicircular groove is embedded in each of the wooden blocks on one side relative to the mast body, and each of the semicircular grooves matches the shape of the corresponding contact surface of the mast body, so that the wooden block and the arc-shaped rod body of the mast body are tightly fitted through the semicircular groove; the height of each of the jigs needs to ensure that when the mast body is in a horizontal position, the platform does not contact the ground, thereby avoiding damage to the platform;

[0010] (4) According to the strength of the mast body, the load-bearing capacity of the lifting lugs and the on-site lifting capacity, the upper lifting lugs, middle lifting lugs and lower lifting lugs are arranged on the outside of the mast body and the positions of the lifting lugs are checked;

[0011] (5) Install equipment that will not interfere with the lifting;

[0012] (6) Lift the mast body in an integrated manner, move it horizontally to the designated position above the dock, then flip the mast from a horizontal state to a vertical state and install it;

[0013] (7) Install the railings on the upper platform and then install the valuable equipment;

[0014] (8) Install the internal equipment of the mast body by installing a maintenance channel;

[0015] (9) Cut off the upper, middle and lower lifting ears.

[0016] Preferably, in the above step (2), a matching sealing plate is added to the inner bottom end of the mast body and painted.

[0017] Preferably, in the above step (4), upper lifting ears are arranged and mounted on the upper end of the side opposite to the reference plane of the mast body relative to both sides of the upper platform, and the two upper lifting ears are arranged on the back of the keel, so as not to damage the structure easily; the two upper lifting ears are both T-shaped lifting ears welded to the mast body at a distance of 200 mm, and the plate thickness is 25 mm; two middle lifting ears are arranged and mounted on the middle part of the side opposite to the reference plane of the mast body, each of which is a D-shaped lifting ear butt-welded to the mast body, and the plate thickness is 25 mm; two lower lifting ears are arranged and mounted on the lower end of the side opposite to the reference plane of the mast body, each of which is a T-shaped lifting ear welded to the mast body at a distance of 200 mm, and the plate thickness is 25 mm.

[0018] Preferably, in the above step (4), the specific process of checking the position of the lifting lug is:

[0019] (4.1) Through 3D simulation inspection, confirm that when lifting with wire rope, there is no interference with the light stand and equipment on the mast body;

[0020] (4.2) Perform finite element calculation and verification based on the mast body during hoisting to confirm the feasibility of the lifting lug position and fine-tune the lifting lug to the optimal position.

[0021] Preferably, in the above step (6), the specific process of integrally hoisting the mast is as follows:

[0022] (6.1) Pass the plate hook through the upper lifting eye, the middle lifting eye and the lower lifting eye respectively, and then slowly lift the mast body by crane until it is completely separated from the fixture, and ensure that the turning action does not interfere with the platform and equipment;

[0023] (6.2) Move the mast body horizontally to the designated position above the dock, and then fine-tune the wire rope to keep the mast body balanced;

[0024] (6.3) Then ensure that the force on the wire rope passing through the middle lifting eye remains unchanged, and by adjusting the different forces on the wire rope passing through the upper lifting eye and the lower lifting eye, gradually tilt the mast body from a horizontal state until it turns to a vertical state, and ensure that the lower end of the mast body is at the bottom;

[0025] (6.4) Adjust the overall direction of the mast body by controlling the force direction of the wire rope passing through the lower lifting lug, and then slowly move the mast body to just above the bottom mast;

[0026] (6.5) Align the mast body with the bottom mast by using the sample punch mark, and then use the level and plumb line to accurately position the mast body, butt weld the mast body and the bottom mast, and grind them to complete the installation of the large mast;

[0027] (6.6) A lining plate is welded at the joint between the mast body and the bottom mast, thereby reinforcing and fixing the overall structure.

[0028] Preferably, in the above step (6.5), it is necessary to ensure that the straightness of the mast body is less than 0.5 mm / m.

[0029] Preferably, in the above step (6.6), there are two types of lining plates: one is a lining plate with a beveled frame, and the other is a lining plate with a regular frame; when there is a difference in plate thickness between the mast body and the butt joint part of the bottom mast, the inner diameter edge of the section with a larger plate thickness is beveled, and a lining plate with a beveled frame is used for welding reinforcement; when the plate thickness of the mast body and the butt joint part of the bottom mast is the same, a lining plate with a regular frame is used for welding reinforcement.

[0030] Preferably, in the above step (8), the installation and maintenance passage is arranged inside the mast body, and comprises a patterned plate passage platform and a step penetrating the inside of the mast body, and a manhole is provided on the patterned plate passage platform near the step.

[0031] Beneficial effects of the present invention:

[0032] (1) The present invention has a reasonable design and is easy to implement on site. It solves the problem of multiple hoisting of large masts and greatly improves the convenience of on-site construction.

[0033] (2) The present invention first confirms the reference plane, and then places the mast body horizontally through a jig, thereby ensuring the stability of the horizontal state of the mast body, effectively preventing deformation, and facilitating subsequent installation operations;

[0034] (3) The present invention determines the mounting position of the lifting lug through 3D simulation and finite element calculation verification, thereby ensuring accuracy and facilitating lifting and installation;

[0035] (4) The present invention adopts integrated hoisting, which not only ensures the integrity and verticality of the mast body, but also reduces the workload of the staff and improves the safety of the staff;

[0036] (5) The equipment on the mast body of the present invention is installed successively at the site and in the dock, thereby preventing the valuable equipment from being damaged during the hoisting process, reducing high-altitude operations, and improving work efficiency;

[0037] (6) The present invention adds a sealing plate at the bottom of the mast body to better protect the internal environment of the mast body and prevent rainwater corrosion;

[0038] (7) The present invention uses the liner plate sample punch mark to facilitate the alignment of the mast body and the mast body at the bottom mast joint, which not only ensures the straightness of the mast, facilitates installation by operators, but also strengthens and fixes the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 It is a schematic diagram of the overall structure of the mast body of the present invention.

[0041] Figure 2 This is a schematic diagram of the finite element calculation verification of the present invention.

[0042] Figure 3 It is a schematic diagram of the T-shaped lifting ear of the present invention.

[0043] Figure 4 Schematic diagram of the D-type hanging ear of the present invention.

[0044] Figure 5 The figure is a schematic diagram of a liner with an oblique frame according to the present invention.

[0045] Figure 6 It is a schematic diagram of the lining plate with regular border according to the present invention.

[0046] Figure 7 It is a schematic diagram of the horizontal placement state of the mast body of the present invention.

[0047] Figure 8 It is a schematic diagram of the hoisting state of the mast body of the present invention.

[0048] Fig. 9 It is a schematic diagram of the turning over state of the mast body of the present invention.

[0049] Fig.10 It is a schematic diagram of the vertical state of the mast body of the present invention.

[0050] Among them, 1-mast body; 2-platform; 3-upper lifting eye; 4-installation and maintenance channel; 5-covering plate; 6-lining plate; 7-middle lifting eye; 8-lower lifting eye. DETAILED DESCRIPTION

[0051] The technical solution of the present invention will be clearly and completely described below through specific implementation methods.

[0052] An integrated installation method for a large mast of the present invention, such as Figures 1 to 10 As shown, the following steps are included:

[0053] (1) The bottom mast between the bow main deck and the second deck is installed integrally with the hull structure, and a sample punch mark is provided at the docking position of the bottom mast to facilitate alignment and docking with the mast body 1.

[0054] (2) The platform 2, outfitting base and cable tray that do not interfere with the lifting are made into an integrated unit with the mast body 1, and a sample punch mark is set at the joint of the mast body 1. The railing on the upper platform that interferes with the lifting is designed to be detachable, thereby reducing the workload of on-site installation in the shipyard and improving work efficiency;

[0055] In the above steps, a sealing plate 5 matching with the mast body 1 is added to the inner bottom end and painted, so that the sealing plate 5 protects the internal structure of the mast body 1 and prevents internal pollution.

[0056] (3) After determining the reference plane of the mast body 1, place the mast body 1 horizontally in the shipyard using a fixture, and ensure that the mast body 1 is placed firmly, and the platform 2 and other outfitting parts are not easily deformed by compression, so as to facilitate the subsequent equipment installation requirements;

[0057] In the above steps, according to the different centers of gravity of the mast body 1 when it is laid flat in different directions, combined with the shape of the mast body 1 and the position of the platform 2, the most suitable side for landing is determined as the reference surface of the mast body 1.

[0058] In the above steps, several jigs are arranged in sequence along the length direction of the reference surface of the mast body 1, and each jig is composed of a jig body and a wooden block; each jig body is welded and spliced ​​by channel steel, and a wooden block is padded between its upper end and the reference surface of the mast body 1, and a semicircular groove is embedded in each wooden block on one side relative to the mast body 1, and each semicircular groove matches the shape of the corresponding contact surface of the mast body 1, so that the wooden block and the arc-shaped rod body of the mast body 1 are tightly fitted through the semicircular groove; the height of each jig needs to ensure that when the mast body 1 is in a horizontal state, the platform 2 does not contact the ground, thereby avoiding damage to the platform 2.

[0059] (4) According to the strength of the mast body 1, the load-bearing capacity of the lifting lugs and the on-site lifting capacity, an upper lifting lug 3, a middle lifting lug 7 and a lower lifting lug 8 are arranged and mounted on the outside of the mast body 1, and the positions of the lifting lugs are checked to facilitate on-site lifting and assembly;

[0060] In the above steps, upper lifting ears 3 are arranged and mounted on both sides of the upper platform 2 at the upper end of the opposite side of the reference plane of the mast body 1, and the two upper lifting ears 3 are arranged on the back of the keel, so as not to damage the structure easily; the two upper lifting ears 3 are both T-shaped lifting ears welded to the mast body 1 by 200mm, and the thickness of the plates is 25mm;

[0061] Two middle lifting ears 7 are arranged and mounted in the middle of the opposite side of the reference plane of the mast body 1. Each of the middle lifting ears 7 is a D-shaped lifting ear butt-welded with the mast body 1, and the thickness of each of the middle lifting ears is 25 mm.

[0062] Two lower lifting ears 8 are arranged and mounted at the lower end of the opposite side of the reference plane of the mast body 1. Each lower lifting ear 8 is a T-shaped lifting ear welded to the mast body 1 with a distance of 200 mm, and the thickness of the plate is 25 mm. In the present invention, since the load-bearing capacity of the T-shaped lifting ear is greater than that of the D-shaped lifting ear, and the force in the middle of the mast body 1 is less than that at its two ends, the D-shaped lifting ear is arranged and mounted in the middle of the mast body 1; in addition, the lower lifting ear 8 not only bears the load but also plays a role in controlling the overall direction of the mast body 1.

[0063] The specific process of checking the position of the lifting lug in the present invention is as follows:

[0064] (4.1) Through 3D simulation inspection, confirm that when lifting with wire rope, there is no interference with the light stand and equipment on the mast body 1;

[0065] (4.2) Perform finite element calculation and verification based on the mast body 1 during hoisting to confirm the feasibility of the lifting lug position and fine-tune the lifting lug to the optimal position.

[0066] (5) Install equipment that does not interfere with lifting (such as various types of lamps, whistles, laying cables, etc.), thereby improving work efficiency, reducing the amount of high-altitude work, and improving safety.

[0067] (6) The mast body 1 is lifted in an integrated manner, moved horizontally to a designated position above the dock, and then the mast is flipped from a horizontal state to a vertical state and installed.

[0068] In the above steps, the specific process of integrated hoisting of the mast is as follows:

[0069] (6.1) Pass the plate hook through the upper lifting eye 3, the middle lifting eye 7 and the lower lifting eye 8 respectively, and then slowly lift the mast body 1 by crane until it is completely separated from the fixture, and ensure that the turning action does not interfere with the platform 2 and the equipment; during lifting, the force is dispersed at multiple force points, thereby reducing the load of the crane, making the lifting process more stable and safe.

[0070] (6.2) Move the mast body 1 horizontally to a designated position above the dock, and then fine-tune the wire rope to keep the mast body 1 balanced.

[0071] (6.3) Then ensure that the force on the steel wire rope passing through the middle lifting eye 7 remains unchanged. By adjusting the different force levels on the steel wire rope passing through the upper lifting eye 3 and the lower lifting eye 8, the mast body 1 is gradually tilted from a horizontal state until it is flipped to a vertical state, and ensure that the lower end of the mast body 1 is at the bottom.

[0072] (6.4) By controlling the force direction of the steel wire rope passing through the lower lifting lug 8, the overall direction of the mast body 1 is adjusted, and then the mast body 1 is slowly moved to the top of the bottom mast.

[0073] (6.5) Align the mast body 1 with the bottom mast by using the sample punch mark, and then use the level and plumb line to accurately position the mast body 1, butt weld the mast body 1 with the bottom mast, and then grind it to complete the installation of the large mast; in particular, it is necessary to ensure that the straightness of the mast body 1 is less than 0.5mm / m.

[0074] (6.6) A lining plate 6 is welded at the joint between the mast body 1 and the bottom mast, thereby reinforcing and fixing the overall structure through the lining plate 6;

[0075] Among them, there are two forms of the lining plate 6: one is a lining plate form with a beveled frame, and the other is a lining plate form with a regular frame; when there is a difference in plate thickness between the mast body 1 and the butt joint part of the bottom mast, the inner diameter edge of the section with a larger plate thickness is beveled, and a lining plate form with a beveled frame is used for welding reinforcement; when the mast body 1 and the butt joint part of the bottom mast have the same plate thickness, a lining plate form with a regular frame is used for welding reinforcement.

[0076] The overall hoisting of the mast of the present invention saves the time of multiple hoisting operations, reduces the man-hours for on-site installation, and improves the convenience and operability of on-site construction.

[0077] (7) As the railings of the upper platform are on the predetermined lifting trajectory, the railings here should be removed first. After the mast is installed, the railings of the upper platform should be installed, and then the valuable equipment (such as radar) should be installed to prevent collision damage during the lifting process and cause unnecessary losses.

[0078] (8) Installing the internal equipment of the mast body 1 (such as compressed air pipes, etc.) through the installation of the maintenance channel 4;

[0079] In the above steps, the installation and maintenance passage 4 is set inside the mast body 1, and it includes a patterned plate access platform 2 and a step that runs through the inside of the mast body 1, and a manhole is provided on the patterned plate access platform 2 near the step to ensure the transparency of the inside of the mast body 1, and the patterned plate access platform 2 can also be used for personnel to take a short rest.

[0080] (9) The upper hanging ear 3, the middle hanging ear 7 and the lower hanging ear 8 are cut off to ensure aesthetics.

[0081] Beneficial effects of the present invention:

[0082] (1) The present invention has a reasonable design and is easy to implement on site. It solves the problem of multiple hoisting of large masts and greatly improves the convenience of on-site construction.

[0083] (2) The present invention first confirms the reference plane, and then places the mast body 1 horizontally through a jig, thereby ensuring the stability of the horizontal state of the mast body 1, effectively preventing deformation, and facilitating subsequent installation operations;

[0084] (3) The present invention determines the mounting position of the lifting lug through 3D simulation and finite element calculation verification, thereby ensuring accuracy and facilitating lifting and installation;

[0085] (4) The present invention adopts integrated hoisting, which not only ensures the integrity and verticality of the mast body 1, but also reduces the workload of the staff and improves the safety of the staff;

[0086] (5) The equipment on the mast body 1 of the present invention is installed successively at the site and in the dock, thereby preventing the valuable equipment from being damaged during the lifting process, reducing high-altitude operations, and improving work efficiency;

[0087] (6) The present invention adds a sealing plate 5 at the bottom end of the mast body 1 to better protect the internal environment of the mast body 1 and prevent rainwater corrosion;

[0088] (7) The present invention uses the punch marks on the lining plate 6 to facilitate the alignment of the mast body 1 with the mast body at the bottom mast joint, which not only ensures the straightness of the mast, facilitates installation by operators, but also strengthens and fixes the structure.

[0089] The embodiments described above are merely descriptions of preferred implementation modes of the present invention, and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary engineering technicians in the field should fall within the protection scope of the present invention. The technical contents for which protection is sought in the present invention have been fully recorded in the technical requirements.

Claims

1. An integrated installation method for a large mast, characterized in that The following steps are involved: (1) The bottom mast between the bow main deck and the second deck is installed in an integrated manner with the hull structure, and a sample punch mark is provided at the butt joint of the bottom mast; (2) The platform, outfitting base and cable tray that do not interfere with the lifting are made into an integrated unit with the mast body, and a sample punch mark is set at the joint of the mast body. The handrail on the upper platform that interferes with the lifting is designed to be detachable; (3) After determining the reference plane of the mast body, place the mast body horizontally in the shipyard using a jig; In the above steps, according to the different centers of gravity of the mast body when it is laid flat in different directions, combined with the shape of the mast body and the position of the platform, the most suitable side for landing is determined as the reference surface of the mast body; In the above steps, a number of jigs are arranged in sequence along the length direction of the reference surface of the mast body, and each of the jigs is composed of a jig body and a wooden block; each of the jig bodies is welded and spliced ​​by channel steel, and a wooden block is padded between its upper end and the reference surface of the mast body, and a semicircular groove is embedded in each of the wooden blocks on one side relative to the mast body, and each of the semicircular grooves matches the shape of the corresponding contact surface of the mast body, so that the wooden block and the arc-shaped rod body of the mast body are tightly fitted through the semicircular groove; the height of each of the jigs needs to ensure that when the mast body is in a horizontal position, the platform does not contact the ground, thereby avoiding damage to the platform; (4) According to the strength of the mast body, the load-bearing capacity of the lifting lugs and the on-site lifting capacity, the upper lifting lugs, middle lifting lugs and lower lifting lugs are arranged on the outside of the mast body and the positions of the lifting lugs are checked; (5) Install equipment that will not interfere with the lifting; (6) Lift the mast body in an integrated manner, move it horizontally to the designated position above the dock, then flip the mast from a horizontal state to a vertical state and install it; (7) Install the railings on the upper platform and then install the valuable equipment; (8) Install the internal equipment of the mast body by installing a maintenance channel; (9) Cut off the upper, middle and lower lifting ears.

2. The integrated installation method of a large mast according to claim 1, characterized in that: In the above step (2), a matching sealing plate is added to the inner bottom end of the mast body and painted.

3. The integrated installation method of a large mast according to claim 1, characterized in that: In the above step (4), upper lifting ears are arranged and mounted on both sides of the upper platform at the upper end of the side opposite to the reference plane of the mast body, and the two upper lifting ears are arranged on the back of the keel, so as not to damage the structure easily; the two upper lifting ears are both T-shaped lifting ears welded to the mast body at a distance of 200 mm, and the thickness of the plates is 25 mm; two middle lifting ears are arranged and mounted on the middle part of the side opposite to the reference plane of the mast body, each of which is a D-shaped lifting ear butt-welded to the mast body, and the thickness of the plates is 25 mm; two lower lifting ears are arranged and mounted on the lower end of the side opposite to the reference plane of the mast body, each of which is a T-shaped lifting ear welded to the mast body at a distance of 200 mm, and the thickness of the plates is 25 mm.

4. The integrated installation method of a large mast according to claim 3, characterized in that: In the above step (4), the specific process of checking the position of the lifting lug is as follows: (4.1) Through 3D simulation inspection, confirm that when lifting with wire rope, there is no interference with the light stand and equipment on the mast body; (4.2) Perform finite element calculation and verification based on the mast body during hoisting to confirm the feasibility of the lifting lug position and fine-tune the lifting lug to the optimal position.

5. The integrated installation method of a large mast according to claim 1, characterized in that: In the above step (6), the specific process of integrally hoisting the mast is as follows: (6.1) Pass the plate hook through the upper lifting eye, the middle lifting eye and the lower lifting eye respectively, and then slowly lift the mast body by crane until it is completely separated from the fixture, and ensure that the turning action does not interfere with the platform and equipment; (6.2) Move the mast body horizontally to the designated position above the dock, and then fine-tune the wire rope to keep the mast body balanced; (6.3) Then ensure that the force on the wire rope passing through the middle lifting eye remains unchanged, and by adjusting the different forces on the wire rope passing through the upper lifting eye and the lower lifting eye, gradually tilt the mast body from a horizontal state until it turns to a vertical state, and ensure that the lower end of the mast body is at the bottom; (6.4) Adjust the overall direction of the mast body by controlling the force direction of the wire rope passing through the lower lifting lug, and then slowly move the mast body to just above the bottom mast; (6.5) Align the mast body with the bottom mast by using the sample punch mark, and then use the level and plumb line to accurately position the mast body, butt weld the mast body and the bottom mast, and grind them to complete the installation of the large mast; (6.6) A lining plate is welded at the joint between the mast body and the bottom mast, thereby reinforcing and fixing the overall structure.

6. The integrated installation method of a large mast according to claim 5, characterized in that: In the above step (6.5), it is necessary to ensure that the straightness of the mast body is less than 0.5mm / m.

7. The integrated installation method of a large mast according to claim 5, characterized in that: In the above step (6.6), there are two types of lining plates: one is a lining plate with a beveled frame, and the other is a lining plate with a regular frame. When there is a difference in plate thickness between the mast body and the bottom mast, the inner diameter edge of the thicker section is beveled, and a lining plate with a beveled frame is used for welding reinforcement. When the mast body and the bottom mast have the same plate thickness, a lining plate with a regular frame is used for welding reinforcement.

8. The integrated installation method of a large mast according to claim 1, characterized in that: In the above step (8), the installation and maintenance passage is arranged inside the mast body, and comprises a patterned plate passage platform and a step penetrating the inside of the mast body, and a manhole is arranged on the patterned plate passage platform near the step.

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