(1) Conduct technical and safety disclosure in accordance with the approved construction organization design (construction plan).
(2) The construction execution process standards, atlases, and specifications are complete.
(3) Before laying the cable tray, check whether there is any place where the cable bridge laying crosses or overlaps with other equipment and pipelines and cannot be constructed. Before construction, negotiate with each type of work, the supervisor, the construction unit and the design unit, and make records to ensure the smooth construction.
(4) According to the construction drawings or cables used in construction, the calculation of cable traction force should be done.
The specification and model of cable tray must meet the design requirements, with complete accessories; All types of steel sections for bridge and accessories, accessories, and fasteners should be galvanized standard parts.
The straight sections, bends, cable tray accessories, supports and hangers, columns and profile steel of various specifications of cable tray shall be provided with product certificates. The inside and outside of the cable tray shall be smooth and flat without burrs, distortion, edge warping and other deformation phenomena.
The ordering or production of the bridge should be carried out according to the design requirements, and there should be no errors. It should be repeatedly checked to avoid waste.
Cable trays should be installed in cable circuits that need to be shielded from electrical interference. In areas with corrosion or flammable dust, closed trays without covers or holes should be selected. When local conditions are required, assembled trays or perforated trays and ladders should be selected; In environments or outdoor areas that are prone to dust accumulation and require covering, it is advisable to have a cover plate. When low-voltage power cables and control cables share the same tray or ladder, a tray or ladder with a partition in the middle should be selected; Appropriate bends should be set up at the branches, leads up, and leads down of trays and ladders; When it is not convenient to install bends due to space limitations or there are special requirements, soft connection plates or hinged plates can be used; Expansion joint shall be provided with expansion board; Connecting two trays or ladders with different widths or heights can be configured with widened or raised boards. However, in construction, the selection of supports, hangers, and cable trays should be based on design or engineering layout conditions.
The width and height of trays and ladders should be selected according to the following requirements:
(1) The filling rate of cables in the bridge should not exceed 40% for power cables; The control cable should not exceed 50%. And a certain amount of spare space should be left for future use in adding cables;
(2) The bearing capacity of the selected tray and bridge specifications should meet the regulations. The working uniform load should not exceed the rated uniform load of the selected pallet and ladder load level;
(3) The relative deflection under uniform working load should not exceed 1/200.
Tray and ladder straight sections can be selected according to the standard length of a single piece. The standard length of a single piece is generally specified as 2, 3, 4, and 6 meters. The commonly used specifications and dimensions for the width and height of trays and ladders are shown in Table 2.4-1.
Note: The symbol △ represents commonly used specifications
The specifications of various bends and accessories should be suitable for the engineering layout conditions and matched with trays and ladders.
The selection of support and hanger specifications should be based on the specifications of trays, ladders, layers, spans, and other conditions, and should meet the load requirements.
The surface treatment method of steel cable trays should be selected based on factors such as engineering environmental conditions, importance, durability, and technical economy. Generally, it is advisable to choose the anti-corrosion treatment method suitable for the engineering environmental conditions according to Table 2.4-2. When using the "T" type anti-corrosion method in the table, such as galvanized nickel alloy, high-purity and other anti-corrosion treatments, the bridge should be tested and verified according to regulations, and should have clear technical quality indicators and testing methods.