Steel structure coating: how to ensure the best protection for industrial metal coatings

Major infrastructures such as airports, ferry terminals, railway stations, and bridges have long service periods, so the metal coatings used for them have very high requirements and need to ensure durability and optimal corrosion protection.

But how can we provide the best corrosion protection for these important steel structures? We enumerate the key factors to be considered in the coating of steel structures.

★ Assess the degree of exposure of steel structure ★

What kind of environment does your steel structure need to withstand? The outer surface may be exposed to various weather conditions, such as rain, snow, direct sunlight, dust, dirt, and soluble salt.
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Although the inner surface of the steel structure is not affected by weather factors, it may be in a high humidity or condensing environment.
Sometimes the environment may be exposed to chemical substances.

Taking the metal exterior surface painting as an example, we cooperated with Ruukki Construction Company to replace the sixth bridge in Finland-Jännevirta Bridge at the end of its service period.
For this large-scale infrastructure, it is vital to protect the bridge from severe weather, wind, precipitation and humidity.

★ Use reliable industrial metal coating ★

Heavy-duty steel structures require high-performance metal coatings.
When applied to these large infrastructures, choose those products that have been tried and tested to avoid any problems before or after the warranty period.

"In these construction facilities that require lifetime service, the performance requirements of the coating are very high, which is why we choose those products that have been tried and tested, so that we can guarantee that we will not encounter any trouble before or after the warranty period.
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——Ruukki Commercial Director of Building Systems

Heikki Wilen

Long-lasting industrial paint can help buildings reduce maintenance and make them last longer.

How can you choose the right metal coating for your steel structure needs? Product selection needs to consider the special requirements of a specific environment.

★ Atmospheric environment ★

In the external environment, choosing a suitable anti-corrosion system is the key to the protection of steel structures.
Coating systems with durability and anti-corrosion properties usually include zinc-rich primers, epoxy resins, polyurethanes, or other topcoat technologies.

Using epoxy type and/or ethyl silicate type zinc-rich primer is one of the most effective methods for steel structure corrosion protection.
As a sacrificial anode, zinc plays a cathodic protection effect on the structure, because zinc oxidizes faster than metal, so zinc protects the steel structure from oxidation in the form of self-sacrifice.

Epoxy intermediate coatings usually contain anti-corrosion pigments.
Epoxy usually uses layered pigments, such as aluminum or mica iron oxide (MIO), to further enhance its barrier protection and prevent water from entering the steel structure and causing internal corrosion.

★ Immersion environment ★

Zinc-containing products are usually not used on steel structures that need to be permanently placed in water or soil.
Under such environmental conditions, thick build epoxy resin coatings with high resistance protection are generally used.
The first layer is usually an epoxy resin containing aluminum and/or MIO, providing a highly cross-linked film.

The anti-corrosion coating system described in the corrosion standard is specified according to the number of coating layers and film thickness.
The higher the anti-corrosion performance requirements, the higher the requirements on the number of layers and thickness of the film.

★ Measure the structure of steel structure ★

In order to ensure the best anti-corrosion effect, it is necessary to measure the construction and design of steel structures.
Avoid choosing structural designs that are easy to collect and store water, dirt and contaminants.
On the contrary, the design of the steel structure should be easy to drain and dry easily.

In addition, if it can dry (very quickly) in rainy weather and outdoor environments, such a coating system can provide longer-lasting corrosion protection.

The metal surface needs to be pre-treated before painting

Before applying any paint to the steel substrate, the surface must be pre-treated to ensure the best performance of the paint.
Surface pretreatment includes not only cleaning the steel, but also ensuring the correct application conditions.
Don't try to skip this step, because surface pretreatment is considered to be the most critical factor affecting the success of the corrosion protection system.

First, remove all impurities, such as grease and dirt, on the steel substrate.
Then use sandblasting to remove the oxide scale, which helps to ensure that the adhesion of the paint is not compromised.

You also need to follow certain standards and specifications based on the climatic conditions and temperature of the application environment.

Take overall anti-corrosion measures for steel structures

There are many factors that are closely related to the corrosion protection of steel structures, including operation methods, equipment, inspections, and knowing how to operate correctly.

If you set aside the steel substrate structure and improperly perform surface pretreatment, simply choosing the correct metal coating is not enough to achieve the best results.

You should consider all aspects and take into account every aspect to ensure that your steel structure is protected from all kinds of corrosion and achieve the best protection.