Series of Posts on Preventing Common Problems in Instrument Installation (II)
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Series of Posts on Preventing Common Problems in Instrument Installation (II): We welcome fellow enthusiasts to actively participate in the discussion of these issues. Constructive suggestions will be rewarded generously; having relevant images will earn additional points as a bonus. By sharing such problems and their solutions, we can avoid similar issues arising in future installations and create a favorable environment for maintenance work. Thank you! 2. After the tray supports are installed, the welds are not protected against corrosion; when the tray passes through floor slabs or fire compartments, the gaps between the tray and the floor slabs or walls are not treated for fire protection. Analysis and prevention: After the cable tray is installed, it is necessary to check promptly whether it is securely and neatly fixed. The surface of the cable tray should be free from any damage in terms of corrosion protection, and it is important to verify that the welds on the support arms have been treated to prevent corrosion; if this has not been done, the contractor must carry out such treatment to ensure the long-term stability of the cable tray. When the cable tray passes through floor slabs or fire compartments, the gaps between the cable tray and the floor slabs or walls must be filled with fire-resistant paint.
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Bridge tray supports are generally prefabricated first (cutting, grinding, welding, corrosion protection, etc.). Once prefabrication is complete, installation begins. For those fixed with bolts, no further corrosion protection is required; for those welded together, the welds need to be treated promptly – slag must be removed and any overly protruding weld beads polished. At the very least, a primer should be applied first； The sealing of cable trays passing through walls and openings is generally carried out after the cables have been installed, the wiring tests have been completed, and it has been confirmed that no further cables will be added, at which point fireproof sealing is performed.
Bridge tray supports are generally prefabricated first (cutting, grinding, welding, corrosion protection, etc.). Once prefabrication is complete, installation begins. For those fixed with bolts, no further corrosion protection is required; for those welded together, the welds need to be treated promptly – slag must be removed and any overly protruding weld beads polished. At the very least, a primer should be applied first； The sealing of cable trays passing through walls and openings is generally carried out after the cables have been installed, the wiring tests have been completed, and it has been confirmed that no further cables will be added, at which point fireproof sealing is performed.
Basic requirements: 1. These guidelines recommend only the fire-sealing method for cable trays passing through floor slabs. 2. Fireproof sealing should be installed at holes in other areas, such as at the entrance where cables enter from the outside into the interior ； At the entrances and exits where cables enter and exit the shafts ； Cables are led to the openings in electrical cabinets, panels, or control screens and consoles ； Where cables pass through holes in partition walls and floor slabs ； Between the main control room or power distribution room and the cable tray ； At both ends of the electrical conduit that crosses fire compartments and vertical shafts across floors ； Other places that need to be configured. 3. When routing cables and insulated wires through steel pipes, steel pipes should be embedded between floors; after wiring is completed, the gaps at both ends of the steel pipes should be sealed with fire-resistant filler. 4. The fire-resistant partition shall be made of mineral wool semi-rigid board (Ef-85 type fire-resistant partition) or steel plates with a thickness of 6 mm or more. 5. The space between the upper and lower fireproof panels can be filled with rock wool or fire-retardant packs, while the gaps in the fireproof panels should be sealed with fireproof mortar. 6. A square sleeve made of 1.5 MM thick steel plate shall be installed at the edges of the tray openings; the height of this sleeve should be 3 CM above the ground level. Alternatively, a water-resistant ring made of plain concrete with a height of 3 CM and a thickness of 2 CM can be used. 7. Fire-resistant materials should also be used to separate the upper and lower layers inside the cable tray. The cable passes through the fire barrier in a sleeve, with the sleeve’s ends filled with fireproof putty. Inside the cable tray, brackets can be installed with fireproof boards on them, or the lower fireproof board can be shaped as shown in Figure (15); fireproof packs can then be inserted inside as shown in Figure (7). 8. The fire sealing method for busbars passing through floor slabs can follow the fire sealing process for cable trays. 9. The cover plates of the cable tray must be disconnected at the points where they pass through the floor slabs. Special fireproof sealing materials – Examples of application methods: 1. Performance indicators of fireproof bags/ignition retardant bags: appearance, loose density, water resistance, oil resistance, compressive strength, impact resistance, and fire resistance. The bag must remain intact without any damage. Density: 0.6×103 kg/m3; Duration of fire resistance: ≥3 days; Compression resistance: R≥0.05 Mpa. First-class fireproof sealing materials have a fire resistance limit of ≥180 minutes