The warehouse storage of Galvanized steel plates requires strict control of environmental humidity below 60%RH (as required by ISO 12944-2 standard). When the relative humidity is ≥85% for 72 consecutive hours, the incidence of white rust increases sharply to 75%. Empirical data from POSCO of South Korea shows that in a closed warehouse equipped with dehumidifiers (dew point ≤-15℃), the proportion of white rust on steel plates can be controlled within 0.3% under the condition that the peak air humidity during the rainy season is 90%, while in an undehumidified warehouse, it can reach 12.7%. It is recommended that the daily humidity monitoring frequency be no less than 4 times, and the fluctuation range should maintain a deviation value of ±5%RH.
The stacking method directly affects the efficiency of air circulation. When stacking steel plates, it is necessary to ensure that the layer spacing is ≥100mm (120-150mm is recommended), and the inclination Angle is suggested to be 5°-10° to facilitate the sliding of condensate water. Tests conducted at the Shenzhen base of China Construction Steel Structure show that when 0.5mm thick galvanized sheets are spaced with 100mm wooden spacers, the air flow velocity between the sheets reaches 0.8m/s, which is 300% higher than that of the dense stacking scheme, and the incidence of white rust drops from 9.1% to 1.2%. For standard plates with a width of 1500mm, the upper limit of the stacking height is recommended to be 3.5 meters to prevent the zinc layer from sticking due to a bottom pressure greater than 20kPa.
The application of protective materials reduces the risk of contact corrosion. Vapor phase anti-rust (VCI) films can release 0.5-1.2mg/m³ corrosion-inhibiting particles, forming a molecular-level protective layer. The JIS Z1535 standard of Japan requires that the coverage rate of VCI film coating be over 98%. The case of China Shipbuilding Industry Corporation shows that this measure has extended the delay time of white rust occurrence from 7 days to 120 days in the coastal storage environment (salt concentration 0.3mg/dm²·d). The recommended base weight of the isolation film is 25-50g/m², with a moisture content of no more than 1.5% to prevent capillary water absorption.
Storage and transportation cycle management follows the “first in, first out” principle. Experimental data show that in the temperate climate zone (with an average annual temperature of 15℃), the safe storage period of untreated galvanized sheets is 180 days. Adding chromate passivation treatment (film weight 1g/m²) can extend the treatment period to 360 days. According to the regulations of the United States Army Corps of Engineers, the turnover cycle of galvanized sheets used for military equipment should be less than 90 days. If the time limit is exceeded, the white rust coverage rate (up to 5%) must be re-tested. The backlog incident at Jurong Port in Singapore in 2024 revealed that the loss rate of white rust on galvanized sheets that were six months overdue reached 22%, far exceeding the normal turnover rate of 1.8%.
Special environments require enhanced protection plans. During sea transportation, the salt spray concentration inside the container can reach 50mg/m³. It is recommended to use a humidity indicator card (10% color change threshold) in combination with silica gel desiccant (dosage ≥300g/m³). Maersk Shipping data: When the dew point temperature difference of the container is greater than 3℃, the two-component VCI bag (with a slow-release rate of 15mg/h) combined with a 65% moisture absorption rate desiccant can ensure zero white rust during a 60-day voyage. Open-air storage yards should be equipped with forced ventilation systems with wind speeds of ≥3m/s. Measurements at the Port of Rotterdam in the Netherlands have shown that this measure has increased the evaporation rate of the water film on the surface of steel plates by 400%.
Inspection and repair techniques reduce the final loss. The portable zinc coating thickness gauge (with an accuracy of ±1μm) can quickly assess the residual amount of zinc coating. When used in combination with weak acid treatment (5% acetic acid solution), it can remove 90% of white rust and the zinc coating loss is less than 1.5μm. Dupont’s repair guidelines state that when the area ratio of white rust is ≤5%, applying alkyd primer (film thickness 25μm) can restore 97% of the anti-corrosion performance. If it reaches 20%, hot-dip galvanizing repair is required (with an increase of 300 yuan per square meter in cost). The EFSA 10/2011 standard mandates that the temperature and humidity records in the storage area be retained for at least 10 years for quality traceability.
The comprehensive prevention and control system has reduced the storage loss rate of Galvanized steel plate to below 0.5% : precise dehumidification keeps the environmental humidity deviation within ±3%RH, and the 120mm layer spacing wooden pad solution has compressed the incidence of white rust to 1.2%. Combined with a 25g/m² vapor phase anti-rust film, the safe storage period can be extended to one year. The real-time monitoring system (with an accuracy of 0.5%RH) and the automatic ventilation linkage device (response time ≤30 seconds) have further reduced the cargo damage rate by 98% and optimized the storage cost by 15.7 yuan per ton per month.