Fireproofing and sealing of cables laid in cable trays

Proper fireproofing and sealing of cable trays involves cleaning, coating, installation of firestop materials, sealing gaps, and thorough inspection to ensure fire safety and compliance.1. Preparation and CleaningBefore fireproofing, ensure the cable tray surface is clean and free of oil, dust, and rust. Rust removal can be done via sandblasting, acid washing, or grinding until a clean metallic shine is visible. This step ensures proper adhesion of primers and fireproof coatings .2. Coating ApplicationPrimer Selection: Use primers with strong adhesion and anti-corrosion properties.Fireproof Coating: Apply fireproof coatings that meet national safety standards using spraying, rolling, or brushing. Control the thickness to achieve the required fire-resistance grade.Topcoat: Apply a durable topcoat with weather-resistant and decorative qualities, ensuring a smooth, uniform finish without drips or bubbles .3. Firestop InstallationWhen cable trays pass through walls, floors, or slabs, seal openings with fire-rated penetration materials:Materials: Firestop packs, mineral wool, firestop mastic, or intumescent caulks.Placement: Install firestop packs in an orderly sequence, ensuring gaps between packs and cables do not exceed 1 cm² and packing thickness is at least 24 cm.Large Openings: Use fire-resistant backing plates before sealing.Special Products: Moldable putty or intumescent caulks can be used to seal irregular openings and cut edges of fireproof mats .4. Sealing and Gap ManagementEnsure all gaps inside and around metal trunking are tightly sealed, both internally and externally.Cover plates should be square, consistent in size, and painted evenly to close openings.Maintain proper clearance between cables to prevent heat accumulation and allow airflow, especially in perforated or wire mesh trays .5. Inspection and AcceptanceCoating Quality: Check for cracks, peeling, or bubbles.Thickness Verification: Use calibrated devices to measure coating thickness and ensure compliance with design specifications.Adhesion Tests: Perform cross-cut or pull-off tests to confirm secure bonding.Fire Resistance Tests: Conduct combustion and endurance trials to verify fire safety standards.Documentation: Record inspection results, dates, and responsible personnel in an acceptance report for future reference .6. MaintenancePeriodically inspect trays for corrosion, coating degradation, or mechanical damage.Ensure grounding continuity and proper alignment of tray connections.Reapply coatings or reseal firestop materials as needed to maintain long-term fire protection . By following these steps, cable trays can achieve effective fireproofing, maintain system reliability, and comply with safety standards in industrial and commercial installations.