(1) The shipping time is long and the voyage period is very susceptible to weather and other factors, which puts forward higher requirements for the validity period of anti-rust packaging.
Due to the continuous volatilization of the corrosion-inhibiting factors in the VCI packaging, the anti-rust period is easy to control, and the anti-rust period is long. Generally, it can be sealed and protected for 5 years at a time, and the longest can be more than 10 years.
(2) Sea winds and waves will cause the hull to shake, and the cargo will be displaced either on the deck or in the cargo warehouse. In extreme weather or the strapping is not fixed enough, it will easily lead to the dumping of the cargo and damage the old packaging.
Since the inside of the VCI rust-proof sealing layer (due to VCI volatilization) is positive pressure when the sealing layer is damaged, the outside water vapor will not enter a large amount of quickly, and the vapor phase corrosion inhibitor is constantly evaporating and replenishing.
Within a period of time, the concentration of VCI in the package and the anti-corrosion ability of the protective film on the metal surface can still be maintained, reducing the probability of failure of the anti-rust package.
For example, in 2003, a company producing electrical equipment in Shenzhen considered that rust often occurred due to the damage of the sealing layer when using the dry air method. To ensure that the products exhibited in Europe were not rusty, they wanted to switch to VCI anti-corrosion technology before use.
A comparative test of storage.
(3) The large temperature difference between day and night at sea causes condensate water to occur from time to time.
For example, 35°C during the day and when the relative humidity is 90%, as long as the Proceedings of the Second Academic Annual Meeting of the Automotive Anti-Corrosion and Aging Branch of the Chinese Society of Automotive Engineers is reduced by 3°C, the saturated humidity will be reached and condensed water will be produced; when the relative humidity is At 80%, a decrease of 5°C can also produce condensed water.
The air used in VCI packaging contains not only water vapor but also saturated VCl molecules. When condensed water is formed, it also contains VCI and still has an anti-rust effect, which is different from other anti-rust methods.
