Hot-Dip Galvanizing of Sections: The EN ISO 1461 Standard in Steel Protection

Hot-Dip Galvanizing of Sections: The EN ISO 1461 Standard in Steel Protection

Hot-dip galvanizing of steel sections is an extremely effective method of protecting structures against corrosion. The entire process is carried out strictly according to the guidelines contained in the EN ISO 1461 standard. As a result, a durable alloy coating is formed on the steel surface. However, the quality of this protection is primarily determined by the chemical composition of the product. Therefore, selecting the appropriate metallurgical charge guarantees obtaining the optimal zinc thickness. For profiles with a wall thickness above 6 mm, it is at least 85 µm. Consequently, the steel gains full protection in C4 and C5 environments for many years.

Silicon Reactivity of Steel and Its Impact on the Coating (Sandelin Range)

To achieve excellent coating adhesion, controlling the silicon (Si) and phosphorus (P) content is crucial. These elements modify the kinetics of the process. As a result, they accelerate or slow down the diffusion between iron and liquid zinc.

In engineering practice, steel behavior is described by specific reactivity ranges:

• Silicon-killed range (Sandelin range): When the silicon content is 0.04% < Si ≤ 0.14%, the reaction occurs violently. As a result, the coating becomes rough, gray, and more brittle.
• Sebisty range: At a concentration of Si ≤ 0.03%, a coating with an exemplary structure is obtained. Furthermore, it exhibits an aesthetic, glossy finish.
• High-silicon range: For concentrations of Si > 0.25%, the thickness of the protective layer increases linearly. What is more, this allows obtaining a very thick protective coating.

Therefore, it is worth considering the analytical specification of the ordered material. Our equal angles and UPN channels are perfectly suited for designing galvanized elements.

How to Properly Prepare Profiles for Hot-Dip Galvanizing?

An undeniable advantage of hot-rolled profiles is their rounded edges. Thanks to this, the risk of coating thinning at the edges is eliminated.

However, the dipping process itself requires a free flow of liquid. This is because liquid zinc has a temperature of approximately 450°C. Therefore, technological holes should be planned during the design of structural nodes. Consequently, gases efficiently escape from inside the elements, and the liquid metal does not form blockages or runs. This solution works well when using unequal angles or T-bars.

Hot-Dip Galvanizing vs. Traditional Painting Systems

Feature / Parameter	Hot-dip galvanizing (EN ISO 1461)	Painting systems (EN ISO 12944)
Reference standard	EN ISO 1461	EN ISO 12944
Type of protection	Barrier and cathodic protection	Physical barrier only
Durability (C4/C5)	Over 20 years maintenance-free	5–15 years (requires service)
Impact resistance	Very high	Medium to low
Hard-to-reach areas	Full interior coverage	Limited access
Cost-effectiveness (LCC)	Low life-cycle costs	High renovation costs

Double Protection: Duplex Systems in Harsh Conditions

In marine environments (C5-M), zinc loss can be significant, ranging from 4.2 to 8.4 µm per year. Therefore, in such conditions, professional hot-dip galvanizing of sections combined with additional powder or liquid coating proves effective.

It is worth noting that the protective effect is not merely the sum of the durability of both layers. As a result, a synergy effect occurs here. Total durability is determined by the formula:

T_total = K · (T_Zn + T_paint)

Where the synergy factor K is: K ≈ 1.5 to 2.3.

Consequently, the paint protects zinc from oxidation. In turn, zinc protects steel against underfilm corrosion at the site of mechanical damage. Furthermore, this solution provides excellent protection for special profiles.

Tonnage Planning and Logistics of Steel Structures

When preparing a quote, the weight gain of the elements must be taken into account. The Fe-Zn layer formation reaction adds between 3% and 8% to the initial weight of the profile.

Therefore, before ordering, it is worth analyzing the product parameters in detail. Our steel weight calculator will be helpful. This tool is based on data from our product catalog. As a result, you will obtain precise tonnage calculations.

You can find all products in our offer section. Furthermore, go to the contact section and consult with our technical department regarding steel selection for galvanizing.