Good knowledge, remember to share in the circle of friends! Some friends have been asking about the construction, installation and quotation of the bridge
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We have also mentioned the relevant contents before
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In this issue, we will summarize the construction specifications and quotation of the bridge in detail
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In a computer room project, compared with the expensive and high-tech hardware and software, the bridge is very insignificant, but it does not reduce the role of the bridge in the computer room
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The bridge is an indispensable part of the whole wiring project
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The design and selection process should be based on the type and quantity of cables in each system, and it is very important to reasonably select the suitable bridge
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In this issue, we will do a bridge topic To understand the construction, installation and calculation of the lower bridge
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1、 Type and selection of cable tray 1
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Selection of type and variety of cable tray 1
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When the cable network to be shielded from electrical interference or the requirements of external protection (such as corrosive liquid, flammable dust, etc.) are required, the (FB) trough type composite anti-corrosion shielded cable tray (with cover) shall be selected
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2
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Class (f) composite epoxy resin anti-corrosion and flame retardant cable tray shall be used in strong corrosive environment
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The same material should be used for bracket and bracket to improve the service life of cable tray and accessories
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Cover plate should be added in the environment or outdoor place where dust is easy to accumulate and other places need to be covered
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3
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In addition to the above situations, tray type, trough type, cascade type, glass anti-corrosion and flame retardant cable tray or steel common type cable tray can be selected according to the site environment and technical requirements
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Cover plate should be added in the environment or outdoor place where dust is easy to accumulate and other places need to be covered
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4
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In the section of public passage or outdoor crossing road, the bottom of the bottom step should be added with backing plate or pallet should be used in this section
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When crossing the public passage with large span, the load capacity of the bridge can be improved or the walking frame can be selected according to the user’s requirements
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5
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Composite bridge (FB) should be used for long span (> 3M)
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6
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Composite epoxy resin bridge (f) shall be selected for outdoor use
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2、 Construction process of cable tray installation 1
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Cable tray installation process: positioning and setting out → embedding iron parts or expansion bolts → supporting, hanging and bracket installation → tray installation → protective grounding installation 2
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Determine the starting and terminal position according to the construction drawing, determine the starting and terminal position according to the construction drawing, mark the direction along the drawing, find out the horizontal, vertical and bending, and walk along the cable tray with powder bag or line drawing Snap or draw lines at the wall, ceiling, floor, beam, plate, column, etc., and draw the position of support, hanger and bracket with uniform span
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3、 Embedded iron parts or expansion bolts 1
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The self-made processing of embedded iron parts shall not be less than 120mm × 80mm × 6mm, and the diameter of anchor round steel shall not be less than 10mm
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2
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Closely cooperate with the construction of civil structure, the plane of embedded iron parts shall be close to the formwork, and the anchoring round steel shall be fixed on the reinforcement in the structure by binding or welding; after the concrete formwork is removed, the plane of embedded iron parts shall be exposed, and the support, hanger or bracket shall be welded on it for fixation
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3
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According to the load of the support, select the corresponding expansion bolt and drill bit; after embedding the bolt, the nut with corresponding washer can be used to fix the support or hanger directly on the metal expansion bolt
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4、 Installation of supports and hangers 1
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The steel used for supports and hangers shall be straight without obvious distortion
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After blanking, the length deviation shall be within 3mm, and there shall be no curl and burr at the incision; 2
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The steel support and hanger shall be welded firmly without significant deformation; before welding, the support and iron parts with thickness more than 4mm shall be beveled, and the weld shall be uniform and flat, and the weld length shall meet the requirements, without cracks, undercut, pores, sags, missed welding and other defects; 3
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The support and hanger shall be installed firmly to ensure the safety The support and hanger shall be installed on the building with gradient and the angle shall be consistent with the building’s gradient and angle; 4
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The specification of support and hanger shall not be less than flat steel 30mm × 3mm; angle steel 25mm × 25mm × 3mm; 5
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It is strictly forbidden to cut any part of steel structure or light steel keel by electric welding; 6
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The universal hanger shall adopt the finalized product and have their own independent lifting fixture or support System
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7
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Generally, the distance between fixed fulcrums should not be greater than 1.5-2m
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Fixed support points shall be set within 500mm at both ends of entry and exit junction box, box, cabinet, corner, turning and deformation joint and three ends of T-joint
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8
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It is strictly forbidden to fix supports and hangers with wooden bricks
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5、 Bridge installation 1
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When the cable bridge is laid horizontally, the support span is generally 1.5-3m, and when the cable bridge is laid vertically, the distance between fixed points should not be greater than 2m
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When the bending radius of the bridge is not more than 300 mm, a support and hanger shall be set at the side of the straight section 300-600 mm away from the junction of the bending section and the straight section
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When the bending radius is greater than 300 mm, a support and hanger should be added in the middle of the bend
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The installation of supports, hangers and bridges must consider that the bending radius of cable laying meets the minimum bending radius of the specification
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See the table below
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The minimum allowable bending radius of cable is less than 2
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Installation of portal angle steel support: ladder type bridge is laid vertically along the wall, portal angle steel support can be used, and the support shall be fixed in coordination with civil construction as far as possible
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As shown in figure 12.3.1.5 (2-1), open angle bolts can also be embedded in civil construction, and the bracket can be fixed with open angle bolts, as shown in figure 12.3.1.5 (2-2), or expansion bolts can be used
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Fig
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12.3.1.5
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(2-1) embedded installation of angle steel support Fig
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12.3.1.5
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(2-2) embedded anchor bolt installation of steel support 3
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Installation of ladder angle steel support: when the bridge is horizontally installed along the wall and column, the supporting wall shall be installed on the special-shaped steel column, and the column shall be installed on the ladder angle steel support, so that the column and the bridge fixed support (or supporting arm) on the wall are in the same line
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See figure and table 12.3.1.5 (3) when underframe and portal frame are welded, the height of welding corner is 5mm
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Table 12.3.1.5 (3) dimensions of ladder type angle steel support (mm) 4
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Side wall installation of cable tray column: column is a component directly supporting bracket, which is divided into steel channel, angle steel and special-shaped steel column; column can be installed on wall, column or suspended on beam plate
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Methods: iron parts can be embedded in concrete; prefabricated blocks can be built in masonry; expansion bolts can also be used, but the concrete strength must be C20 or the brick strength must be above mu10
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The method can refer to 12.3.1.5 (4a, B, C, D, e, f)
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Fig
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12.3.1.5 (4C) installation method of profiled steel column on the side wall of the wall part 1 5
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The cable tray shall be laid under the flammable and explosive gas pipe and heat pipe
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When there is no design requirement, the minimum clear distance between the cable tray and the pipe shall comply with the provisions of 12.3.1.5 (5)
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Indicates the minimum clear distance between 12.3.1.5 (5) and the pipeline
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6
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Bracket installation: bracket is a rigid part directly supporting tray and ladder separately fixed
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Bracket is fixed with bolts, which can be embedded with bolts, can also be expanded with bolts, and can also be clamped, as shown in Fig
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12.3.1.6 (1), (2), (3), (4), (5)
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If you still don’t know the above process, you can watch the video of cable tray installation: 3
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Precautions for cable tray installation 1
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Construction requirements 1
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Steel cable tray in straight section is longer than 30m, aluminum alloy or glass fiber reinforced plastic cable tray is longer than 15m, expansion joint shall be set, compensation device shall be set at the place crossing the expansion joint, and bridge with expansion joint can be used
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2
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The bolts between the bridge and the support and the bolts of the bridge connecting plate are fastened without omission, and the nuts are located outside the bridge
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When the aluminum alloy bridge and the steel support are fixed, there are mutual insulation and anti-corrosion measures, and generally asbestos pad can be padded.
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