Once high-strength bolts rust, not only does it affect their appearance, but it also weakens their load-bearing capacity and connection reliability, potentially leading to structural safety hazards in severe cases. Preventing high-strength bolts from rusting requires a comprehensive approach encompassing four aspects: storage environment control, packaging protection, surface treatment, and usage management. The specific measures are as follows:
Storage Environment Requirements (Moisture and Contamination Prevention are Key)
Core Principles: Dryness, ventilation, rain protection, dust protection, and categorized storage.
Environmental Conditions
They must be stored in a dry, well-ventilated, rainproof, and moisture-proof indoor warehouse. Open-air storage is strictly prohibited.
The warehouse floor should have moisture-proof measures. The bottom of the packaging boxes should be elevated at least 300mm above the ground to prevent ground moisture intrusion.
Avoid contact with corrosive substances such as acids, alkalis, and salts to prevent electrochemical corrosion.
Categorization and Labeling Management
Store them according to batch number, specifications, and type. Mixing batches is strictly prohibited. Ensure that bolts are used in conjunction with the same batch during construction.
The batch number, specifications, and quantity should be clearly marked on the outside of the packaging boxes. Strict verification is required upon receipt to avoid misuse.
Stacking and Handling Requirements
When stacking original boxes, the height of each stack should not exceed 1.5 meters, and the width should not exceed 2 meters, with ventilation gaps between stacks.
When storing on indoor shelves, stacking should not exceed three layers to prevent deformation of the bottom layer under pressure.
Handle with care, avoiding dropping or collisions to prevent damage to packaging and threads.
Rust Prevention Measures (Comprehensive Protection from Factory to Use)
1. Surface Treatment Before Factory Delivery (Long-lasting Rust Prevention Base)
Electro-galvanized/Hot-dip galvanized: Forms a zinc layer on the bolt surface, preventing rust through cathodic protection. Suitable for general atmospheric environments.
Dacromet (Zinc-Chromium Coating): An inorganic rust-preventive coating with strong corrosion resistance, suitable for harsh environments such as high humidity and high salinity.
Blackening Treatment (Oxide Film): Forms a black oxide film. Low cost but weak protection; requires the use of rust-preventive oil.
Phosphating Treatment: Creates a phosphate film. Good rust prevention and compatible with subsequent painting; commonly used for short-term storage.
2. Packaging and Storage Protection: Use VCI vapor phase rust inhibitor bags for sealed packaging. Rust-preventive gas molecules evenly cover the bolt surface, effectively preventing moisture and rust.
Use moisture-proof packaging bags or sealed plastic boxes for individual packaging to avoid moisture absorption due to changes in ambient humidity.
Do not open the box before use. Unused bolts should be resealed after opening to prevent dust and moisture intrusion.
