1、 Common knowledge for storing galvanized products during rainy season

In the hot and humid weather of summer, there is a lot of rain, and the weather is even more humid and hot after rain. Galvanized products in this state are prone to anti alkali (commonly known as white rust) phenomenon on their surface. Therefore, new and old users must know some common knowledge about storing galvanized products in the rainy season!

Storage conditions for galvanized products during rainy season

1. In rainy and foggy weather, try to store indoors or cover with tarpaulins. After the rain stops and the fog dissipates, remove the tarpaulins to maintain ventilation and dryness;

2. Avoid direct contact with damp soil when stacking.

Treatment methods for water and moisture ingress in galvanized products

1. In case of water ingress, the entire piece should be immediately disassembled and placed in a ventilated area to dry;

2. If there is slight white rust or spots on the surface, it should be immediately disassembled and dried. After the white rust turns into powder, it should be wiped off in a timely manner. Hot dip galvanized manual self painting should be used for coverage spraying, which does not affect the rust prevention effect.

be careful!

Galvanized products are not afraid of rain, but they are afraid of being covered!!! If the entire product is submerged in water, white rust will appear within 1-2 days. Please pay attention to avoiding damage in a timely manner!!!



2、 Common knowledge of alkali return (white rust, black spots) in galvanized products

Firstly, the causes of alkali return (white rust, black spots)

1. Formation mechanism of white rust

When galvanized parts are tightly stacked and placed in humid air, due to the lack of free flowing air between the surfaces of the plated parts, the local surface of the coating will undergo electrochemical corrosion, forming white rust. Due to the interaction between a layer of condensed water attached to the surface of the galvanized layer and oxygen, carbon dioxide, hydrogen sulfide, sulfur dioxide, oxides, and other chemical gases, a corrosive aqueous solution is produced and adheres to the surface of the zinc layer, forming an electrolyte. This electrolyte electrochemically corrodes the zinc layer, resulting in a powdery substance (zinc oxide) called white rust visible to the naked eye. The secondary and tertiary oxidation products of white rust form a localized black appearance, which is collectively referred to as the alkali return phenomenon.

2. The impact of white rust

Due to the volume increase of 3-5 times when metallic zinc is transformed into zinc oxide or zinc hydroxide, the formed white rust has a larger volume, making the corrosion degree of white rust appear much more severe than the actual situation, seriously affecting the appearance of the coating. However, in fact, they only cause minimal loss of zinc in the base coating. For thicker structural component coatings, white rust usually has no or no significant impact on the durability and service life of the coating.

3. Treatment of white rust

There may be a large amount of white rust on the surface of galvanized parts, but the actual corrosion of the coating is relatively mild. In most cases, the appearance of white rust does not indicate that the coating has been severely damaged, nor does it necessarily mean that the service life of the plated parts will be reduced. After white rust occurs, the plated parts should be moved away to quickly dry their surfaces. The typical white and gray corrosion products on parts that have been stored for a long time and have white rust may turn black. When this situation occurs, as long as the zinc layer is thick enough, it will not affect the service life. In GB/T13912-2020, it is explicitly stipulated that as long as the thickness of the coating is greater than the specified value, uneven areas of dark or light gray color are allowed on the surface of the coated parts. Galvanized workpieces stored under humid conditions are allowed to have white rust (white or gray corrosion products mainly composed of basic zinc oxide) on the surface.

In summary, due to factors such as weather, transportation, and storage, the phenomenon of white rust is a common occurrence in galvanized products during summer. As long as the corroded zinc layer exceeds the standard value, it will not have any impact on the service life of the product.

Secondly: Precautions

1. All galvanized products will produce white rust in humid, high-temperature, poorly ventilated, and corrosive environments. Products that are prone to white rust: angle steel, flat iron, steel plate, small-diameter square tube, and other products that are tightly packaged and sealed. When water accumulates inside, the weather is hot and humid, and the accumulation of water and moisture can easily cause the phenomenon of galvanized products shouting back

2. For products that have been galvanized, customers are requested to ship them in a timely manner, unpack and store them upon arrival at the destination, keep the warehouse ventilated, and remember not to cover the package.

3. If there is slight white rust or spots on the surface, it should be immediately disassembled and dried, ventilated until the white rust turns into powder, and then wiped off with a brush in a timely manner. Hot dip galvanized manual self painting should be used for covering spraying, which does not affect the anti-corrosion effect.

4. In humid and hot weather, try to store indoors and keep it ventilated and dry. When stacking, avoid direct contact with damp soil.

5. Galvanized products are not afraid of high temperature, humidity, or centralized stacking, but they are afraid of having all three at the same time, that is, they should be stacked in a humid (including rain, fog, and>50% air humidity) and hot (temperature>26 ℃) environment.

Thirdly: Key points

If the coated goods are not picked up in a timely manner, or if they are not unpacked and used in a timely manner upon arrival at the destination, resulting in alkali return, the company will not be held responsible for any losses caused by uncontrollable rainy weather conditions.