Stainless Steel Packaging and Marine Shipping Protection: Most Rust Spots Are External Contamination
Rust spots on stainless steel after marine shipping are mostly not defects of the material itself, but the combined effect of carbon steel contamination, chloride attachment, and condensation; packaging isolation and desiccants are key.
In the high-salinity, high-humidity marine environment, if the stainless steel surface comes into contact with carbon steel dust, iron filings, or chlorides in packaging materials, pitting corrosion and surface rust spots can easily form.
Packaging recommendations: 1) Avoid direct contact with carbon steel; dunnage and packaging materials should be chloride-free (control chloride ion content); 2) When covering coil/sheet surfaces with protective film, pay attention to adhesive residue and air venting; 3) Place desiccants inside the container and record the quantity and location; 4) Before loading, check whether the container body leaks water and whether fertilizer/salt cargo residues remain.
Incoming inspection: First distinguish between surface-adhered rust and pitting pits; adhered rust can be removed by acid pickling and passivation, while pitting pits require assessment of depth and distribution. Transport protection and incoming acceptance methods can be stipulated in the contract to reduce disputes.