Anti-corrosion Work for Port Cranes

2025-12-14 19:55:44

Anti-corrosion Work for Port Cranes

Port Cranes operate in harsh marine environments characterized by high salt spray, humidity, and ultraviolet radiation, making corrosion a primary threat to structural integrity and operational safety. Effective anti-corrosion work is a systematic project integrating material selection, surface treatment, coating protection, and regular maintenance, which directly extends the service life of equipment and reduces operational risks.

Surface preparation is the foundation of anti-corrosion protection and must comply with ISO 8501-1 standards. For new cranes or full-scale overhauls, abrasive blasting is the preferred method to achieve Sa2.5 grade, removing all rust, oil stains, and loose attachments, and creating a surface roughness of 30–75 μm to enhance coating adhesion. Local repairs can use power tools to reach St3 grade. After treatment, the surface must be dried to a moisture content ≤4% within 4 hours and immediately coated to avoid re-rusting.

A three-layer coating system is widely adopted for long-term protection, with a total dry film thickness of 250–300 μm for C5-M marine atmospheric environments. The epoxy zinc-rich primer (70–100 μm) provides cathodic protection, using zinc powder to sacrifice itself and shield the steel substrate. The epoxy micaceous iron oxide intermediate paint (100–150 μm) forms a dense barrier to block the penetration of chloride ions and moisture. The aliphatic polyurethane or fluorocarbon topcoat (70–100 μm) offers excellent weather resistance, anti-UV aging, and self-cleaning properties, preventing coating chalking and cracking. Special attention should be paid to coating corners, welds, and bolt connections with a brush to avoid missed coating.

For key vulnerable parts, targeted anti-corrosion measures are essential. Bolted joints, pins, and other metal-to-metal contact areas can be treated with hot-dip galvanizing or dacromet coating, and supplemented with anti-rust grease. Underwater components and tidal zone structures can combine coating protection with cathodic protection: sacrificial anode cathodic protection using zinc or aluminum-zinc alloys is suitable for local areas, while impressed current cathodic protection is more applicable for large-scale underwater foundations. Dynamic parts such as boom hinges and pulley shafts should use wear-resistant and corrosion-resistant composite coatings to balance lubrication and protection needs.

Regular maintenance is critical to sustaining anti-corrosion effectiveness. A bi-annual cleaning of the crane surface to remove salt deposits and dust is required, along with inspections for coating defects such as blistering, peeling, and rust spots. Localized damage should be repaired promptly by grinding to the sound coating, re-preparing the surface, and reapplying the coating system. A full coating renewal should be carried out every 5–8 years based on the coating condition assessment. All operations must comply with industry standards such as JT/T 733-2021 to ensure the standardization and effectiveness of anti-corrosion work.