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Hot-Dip Galvanizing
Metal structures
Custom Orders

Custom orders involve the development of design documentation according to the clients' individual projects. The company 'Metal Invest' executes such tasks 'turnkey,' handling all processes of manufacturing metal structures of any volume and complexity.

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More than 500 clients use our services annually
What is the lifespan of hot-dip galvanized coating?
The lifespan of hot-dip galvanized coating (34-170 years) is entirely predictable and is determined by the coating thickness and the type of aggressive activity in the specific area. Zinc protects steel for a very long time, allowing for energy and resource savings with minimal environmental impact. For example, enough energy is saved on each ton of protected steel to meet the energy needs of an average family for several weeks.
Why are some metal structures glossy after hot-dip galvanizing and others matte?
The outer layer of zinc provides a shiny appearance; if this layer has time to react with iron during cooling (in the case of reactive steel galvanizing), the appearance of the product becomes less attractive. The amount of silicon (Si) and phosphorus (P) in the steel, as well as the way the rolled products are manufactured, can affect the reaction of steel with molten zinc. Table 1 of EN ISO 14713-2 (see below) provides a simplified guide to the characteristics of galvanizing coatings. Translated with DeepL.com (free version) Table 1 Coating characteristics depending on steel composition
Category Typical levels of reactive elements, %. Additional information Typical characteristics of the coating
А <0,03% Si і <0,02% P See NOTE 1 and NOTE 4 The coating has a shiny appearance with a fine texture. The coating structure contains an outer layer of zinc.  
B S 0,14% Si до <0,25% Si Other elements can affect the reactivity of the steel. In particular, a phosphorus level of more than 0.035% results in increased reactivity. The coating can have a shiny or matte appearance. The structure of the coating may include an outer layer of zinc or an iron-zinc alloy may reach the surface of the coating, depending on the composition of the steel.
C від> 0,03% Si до <0,14% Si Overly thick coatings may be formed. The coating has a darker appearance with a coarse texture. Iron and zinc alloys predominate in the coating structure and often extend to the surface of the coating, which reduces resistance to handling damage.  
D > 0,25% Si The thickness of the coating increases with increasing silicon content.  
NOTE 1 Steels with compositions satisfying the formulas Si < 0.03% and Si + 2.5P < 0.09% should also exhibit these characteristics. For cold-rolled steels, these characteristics are expected to be met if the steel composition satisfies the formula Si + 2.5P < 0.04%. NOTE 2: The presence of alloying elements (e.g., nickel or aluminum) in the zinc melt can significantly affect the coating characteristics listed in this table. This table does not provide appropriate guidance for high-temperature galvanizing (i.e., immersion in molten zinc at 530°C to 560°C). NOTE 3 The composition of the steel listed in this table will vary due to other factors (e.g. hot rolling) and the limits of each range will vary accordingly. NOTE 4 Steels with a composition of <0.01% silicon that also have an aluminum content >0.035% may exhibit lower reactivity, which may result in lower than expected coating thicknesses. These steels may have a reduced level of coating cohesion. NOTE 5 - The design of the galvanized product may also affect the performance of the coating.
 

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