Prado Silos steps into 2024 with significant upgrades in the steel used for its metal silos, and an improvement in the guaranteed service life of new projects: from now on, the steel for the manufacture of silos will receive ZM310 coating, from the roof to the cylinder, thus ensuring three to five times more protection against corrosion than the traditional 100% zinc coatings offered by other manufacturers.
The special formulation of ZM310 coating lies in a combination of zinc, aluminium and magnesium, which results in a higher corrosion protection than other types of coatings, in addition to a much more effective performance against rust appearance on steel profiles and cuttings, which is key for the proper maintenance of silos. Although ZM310 coating is thinner (in fact, this results in a more homogeneous and stable application on the steel surface), a 25 micron layer provides a more efficient and longer-lasting steel protection than the 42 micron coverage of the Z600 galvanised coating.
Corrosion is the main natural process affecting the service life of any metallic silo system, and this can be especially problematic for industrial environments or in tropical climates. Corrosion is a physical-chemical reaction occurring in any metal when exposed to its environment, ultimately affecting its composition and performance. From changes in the appearance of the material to serious alterations and damage to the steel (which may constitute an operational and safety risk), the effects of corrosion are multiple and can vary. Therefore, a reinforced protection against corrosion leads to more durable silos and safer storage management.
Accordingly, Prado Silos was already using ZM310 coated steel for manufacturing the silo roofs, the most exposed parts of the structure and potentially the most problematic in the management of bulk materials. However, as part of our continuous product improvement process, we are now extending the use of ZM310 coating to the steel used to build the entire cylinder of the silo, thus guaranteeing increased protection and safety.
In its natural state, steel is extremely vulnerable to corrosion. Despite its structural strength, steel’s exposure to the environment causes a series of physical-chemical reactions that can damage this material much sooner than other metals. This is why manufacturers have reinforced steel with special coatings designed to prevent direct exposure, meaning that the outer layer can withstand the most adverse effects of corrosion.
Historically, steel products have relied on zinc coatings, as they perform up to 10 times better than steel in terms of resistance to corrosion. As long as the zinc withstands the wear and tear caused by the environment, the steel remains in good conditions. However, once the zinc coating becomes degraded by corrosion, the steel is exposed and begins to deteriorate.
Zinc has been a powerful friend when it comes to avoid corrosion, but its properties are limited: as a result of corrosion, white stains gradually appear on the surface, which in fact are deposits of zinc oxide. Zinc presents a porous structure that is unable to durably withstand the effects of the environment, leading to accelerated exposure of the steel to the elements.
To overcome this deficiency concerning zinc, steel manufacturers have developed a combination of coating materials that outperforms traditional protections made exclusively with zinc.
ZM310 coating adds magnesium and aluminium to the zinc in the immersion casting process, resulting in a much more durable and stable coating performance. When exposed to the environment, ZM310 creates a highly dense and compact layer on top of the coating, referred to as ‘Simonkolleite’, which forms a blocking barrier against corrosion, in contrast to the porous zinc oxide surface of traditional galvanised coatings.
Furthermore, this dense layer spreads uniformly over the entire surface of the steel, fitting both in flat and curved sheets — and this is particularly relevant when dealing with metal silos, where the surfaces of reinforcements and ferrules usually present corrugated and bent profiles.
In the manufacture process of our silos, the steel is subjected to numerous operations: cutting, stamping, corrugation, etc. Ultimately, these processes will have an effect on the coating, since certain sections of the steel will remain exposed, generating a risk of corrosion. This is also the case on construction sites and during assembly operations, when impacts and scratches can damage the steel’s protection.
An outstanding feature of ZM310 coating is its ability to repair itself, also known as self-healing or self-repair. The Simonkolleite layer created on the surface of the steel, supported by the zinc included in the ZM310 formulation, spreads over time to all exposed parts, moving through the cut areas and ultimately covering the entire surface of the silo.
Extensive studies and field tests show that the ZM310 coating performs significantly better than other solutions, extending the service life of metal silos and increasing the safety and stability of their construction. Consequently, this has encouraged an increasing number of steel manufacturers to adopt this treatment for their products, and now Prado Silos can offer the best protection against corrosion for steel storage solutions.
When protected with ZM310 coating, a steel silo will guarantee a longer and safer service life, while ensuring the most efficient investment for the best possible storage.