Corrosion Protection for Container House Exterior
Corrosion protection for the exterior of container houses requires a comprehensive approach encompassing material selection, surface treatment processes, environmental and structural design, and maintenance:
1. Material Selection as the Foundation Weather-resistant steel is the core material, such as Q355NH or Q345GNH conforming to the GB/T 4171 standard. By adding alloying elements like copper and phosphorus, a dense oxide layer can form on the surface, significantly enhancing corrosion resistance. The base plate should be profiled steel sheets (GB/T 12755) with a zinc coating weight of no less than 275 g/m² (both sides) to serve as an anti-rust base layer. Insufficient zinc coating thickness or substandard steel quality will directly weaken the anti-corrosion performance.
2. Standardized Surface Treatment Processes
- Pretreatment Layer: Thoroughly remove oxide scale and oil stains through sandblasting (with a roughness of Sa2.5 grade) or chemical cleaning to ensure coating adhesion.
- Coating System: Adopt a composite structure of "primer + intermediate coat + topcoat". The primer should be an epoxy zinc-rich paint with a zinc powder content of ≥70% (dry film) and a thickness of 60-80 microns to form cathodic protection. The intermediate coat uses epoxy mica iron paint (50-70 microns) to enhance density. The topcoat employs polyurethane or acrylic polyurethane paint (40-60 microns) to provide weather resistance and color retention. The total dry film thickness of the coating is recommended to be 200-250 microns (for C3-C4 corrosion environments), and it should be increased to over 280 microns in coastal or chemical industrial areas.
- Alternative Solution: After sandblasting, directly apply anti-rust paint. Strictly follow the number of coats and drying times specified in the product instructions to avoid missed coats or insufficient thickness.
3. Optimized Environmental and Structural Design
- Moisture Prevention: Elevate the container bottom by 30-50 centimeters using concrete foundations or steel feet to avoid direct contact with ground moisture.
- Drainage System: Design the roof with a slope of ≥5% and install eaves troughs and downspouts to prevent rainwater accumulation.
- Ventilation Control: Install turbine ventilation caps on the top or side walls to keep the internal relative humidity below 60% and reduce condensation formation. Poor ventilation will lead to an increase in internal humidity and accelerate metal corrosion.
4. Key Daily Maintenance
- Regular Inspections: Focus on inspecting easily corroded areas such as welds, bolt connections, and door and window edges every 3-6 months.
- Coating Repair: When scratches or rust spots are found, sand them down to a metallic luster and then apply epoxy primer and a matching topcoat in sequence.
- Metal Part Maintenance: Apply lithium-based grease or anti-rust oil to hinges, door locks, and other components every quarter to prevent friction corrosion.
- Maintenance in Special Environments: In coastal areas (C5-M corrosion grade) or chemical industrial areas, conduct professional maintenance every six months, including coating inspection and local touch-up painting.
