PPGI must be stored in such a way as to avoid the possibility of its mechanical damage and corrosion.
Coated metal is subjected to corrosion?!
If the coating is zinc, then the so-called white corrosion can form on its surface. “White rust” is zinc oxide in the form of a loose white stain on the surface of a galvanized product. PPGI may be exposed to the risk of under-film corrosion due to a combination of unfavorable circumstances: use of poor-quality or incorrectly selected passivation, improper application of primer and topcoat (violation of technological conditions) and exposure to atmospheric conditions.
Should coated steel be stored indoors?
There are disputes and discussions on this issue, and there is no unequivocal answer to this question. There are requirements of regulatory documents (for example, GOST 14918-2020, GOST 34180-2017), recommendations of coil manufacturers. Even indoors, a humid climate can occur that promotes corrosion. In winter, when coils are moved from outside to a warm workshop, condensate is formed on the surface of the metal, even between the coil wraps. The longer the coil is stored in such wet condition, the greater the risk of white rust on the surface of the galvanized strip. On the other hand, coil storage on the outside, where it is directly exposed to atmospheric conditions, is also highly likely to lead to corrosion.
How to prevent corrosion?
General recommendations are as follows. Coils with zinc and/or polymer coating should be stored in a dry place. If moisture lands on the coil surface, it should be quickly removed by drainage or evaporation. For the same purpose, air circulation should be provided in the coil storage area. It is important to ensure correct packaging of the coils, because the packaging is the first to take on the blow, both mechanical and climatic.
In addition, it is recommended to PPGI before processing for no more than 6 months.
Subject to following these recommendations, precoated metal will keep its protective and aesthetic properties for years to come.
