How do desiccants prevent rust and corrosion?
In the manufacturing industry, parts are sometimes designed in one location, manufactured in another, and packaged and delivered to the third location for final assembly or storage. Sometimes, these locations are relatively close together and may even be in the same country. In many other cases, however, the manufacturing of parts and final assembly processes may be thousands of miles apart, necessitating the shipment of containers across continents or seas.
The temperature and humidity of the air surrounding packaged items inside the containerised cargo can change dramatically during long-distance shipments. “Container rain” is the effect of leftover moisture in ambient air, packaging materials, or even wooden container floors condensing quickly inside a container. Since surface rust can start to form at relative humidity values of 40% or more, moisture-sensitive components, especially ferrous metals, are at risk. The damage risk increases when parts are exposed repeatedly to excessive humidity or water droplets.
Manufacturers and shippers can prevent moisture damage by using desiccants in the packaging and shipping containers. Desiccants assist in diffusing or removing moisture to maintain the desired amount when residual moisture or container rain accumulates within cargo ships.
Today’s market offers a wide selection of desiccants—desiccant systems aid in preserving the correct humidity levels to stop rust and corrosion of delicate components.
Silica gel is the primary desiccant substance used in desiccant absorbents. Silica gel’s immense surface area and very porous molecular structure make it highly effective in absorbing moisture from the air.
Silica gel’s molecular structure has a strong attraction for both water and moist air. The bound water molecules form a unique bond, allowing water to be extracted from the air without absorbing other polar or hydrocarbon components. Removing all humidity from the environment and maintaining stable humidity levels resolve rust and corrosion issues.
Shipping Container Desiccant is a quick, dependable, and affordable packaging solution for reducing or preventing moisture damage in enclosed containers. When placed inside a sealed container or packaging, desiccants protect many goods, including automobile parts, metal parts, heavy machinery, and food cartons. The desiccant is made from a heated, naturally occurring mineral. They remain free-flowing after complete adsorption and are noncorrosive, neutral, and inert.
By employing Desiccants, the package’s relative humidity can be lowered below 40% R.H., providing dependable protection against rust, corrosion, and other moisture-related issues.
Shipping Container Desiccants aids in preventing costly metal parts from being damaged during container shipments of automotive parts by “container rain” or excessive moisture. It absorbs excess moisture and keeps it in a thick, no-spill gel when employed in containers in the shape of bags, strips, poles, or blankets. Despite the temperature, Shipping Container Desiccants’ drying action keeps the air’s relative humidity at 40%, well below the “dew point,” the temperature at which moisture condenses and container rain occurs. When used as directed, it provides affordable moisture protection for containerised items during even long journeys.
Do desiccants work effectively to prevent corrosion?
Moisture, humidity, and condensation are the leading causes of rust and metal components’ rust and corrosion. VCI and desiccant offer unique defences against the corrosive effects of rust and corrosion on metal items. VCI and desiccant are appropriate for storage or shipping metal parts, and both are most effective when used in an enclosed location.
However, desiccant and VCI use very distinct chemistry to protect metal in very different ways. Their differences can be described using a give-and-take analogy. While desiccant “takes” or adsorbs moisture from the packing environment to prevent metal corrosion, VCI “gives” or emits a vapour that eventually forms a protective layer on the metal’s surface. Depending on the application and the storage or shipping environment specifics, one technique may outperform another, or users can use both VCI and desiccant for better metal protection.
How does it work?
Volatile Corrosion Inhibitors are a group of chemical substances that release vapours into confined spaces that prevent rust. The VCI molecules create a tiny barrier on the surface of ferrous and non-ferrous metal once the VCI vapours are released. VCIs actively protect the metal from corrosion via “passivation” by forming a stable oxide layer on the metal surface, creating an invisible shield on the metal’s surface that prevents rust.
When packaging materials like paper or poly film are made into rolls, sheets, bags, or tubing, VCI is embedded. The VCI is released and activated when metal is encased, wrapped, or covered in VCI packaging for shipping or storage.
Metal and metal components are not altered, affected, or left with a residue by VCI chemistry. Both pieces of clean metal and those with a coating or finish can use it. When metal is taken out of its packaging, the VCI soon disappears, leaving metal pieces usable.
An alternative to VCI, desiccants are drying chemicals that lower humidity and moisture levels in confined spaces. To stop corrosion and harm to metal, they aid in controlling and removing moisture and condensation from sealed product packaging, bins, crates, containers, or totes.
Desiccant is made from adsorbent materials such as silica, activated charcoal, bentonite clay, or calcium chloride, which are drying agents. These drying agents look solid to the unaided eye; they often take the shape of tiny beads, grains, or pellets. The surface is porous, which explains why they can keep a lot of the moisture that makes up their weight.
Desiccant is an alternative for rust prevention that is, without a doubt, practical, but it’s crucial to understand its limitations, as adsorbing moisture is the primary function of a desiccant. In contrast to VCI, they do not actively preserve the metal surfaces of metal components or stop corrosion from starting. If a desiccant packet comes into contact with water and metal parts, rust may develop where the two materials are in contact. Placing the desiccant packet(s) inside the product packaging away from any metal or metal components is advised for most desiccant applications.
Desiccant excels as a dehumidifier for packaging, but what happens when it pairs with VCI in the packaging? Desiccants combined with VCI will be a suitable packaging solution for goods in harsh environments. VCIs use adsorption, and desiccants function via absorption. Desiccants “bring up the rear” by reducing moisture and condensation. In contrast, VCI packaging acts as the “first line of defence” by providing a physical barrier and a blanket of protection on the surface of the metal to defend against external conditions.