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Hot Dip Galvanisation: Superior Steel and Iron Preservation


Immerse yourself into the world of hot dip galvanisation and discover why it might be the best metal finish solution to protect your iron and steel components.

Even the most durable metals like steel and iron can’t withstand the elements without the necessary protection. And when it comes to protecting metal from corrosion, perhaps nothing offers the durability, longevity and cost-effectiveness as hot dip galvanisation. 

But what exactly is hot dip galvanising, and does it offer the best protection for your requirements?

In this blog, we discuss what distinguishes hot dip galvanisation from other metal finish alternatives, looking at the science and method with time at the end for seven key benefits. 

Let’s explore.

Immerse yourself into the world of hot dip galvanisation and discover why it might be the best metal finish solution to protect your iron and steel components.

What is Hot Dip Galvanising?

The hot dip galvanising process involves coating iron and steel with zinc. When your base metal gets immersed in the molten zinc, it alloys with the surface. After immersion, the elements react with the oxygen in the atmosphere to form zinc oxide and zinc carbonate. This metallurgical reaction provides the resistance your steel or iron needs from corrosion. 

Essentially, the purpose of applying this zinc finish protect surfaces from rusting. The long-lasting effects make hot dip galvanisation ideal for steel structures and other components exposed to moisture.

First conceived in 1742 by French Chemist Paul Jacques Malouin, it was almost 100 years later that fellow countryman and chemist Stanislas Sorel obtained a patent for coating iron with zinc after cleaning it with sulfuric acid and fluxing it with ammonium chloride.

Various industries across the globe, such as construction, continue to drive the galvanised steel market, with the hot dip galvanisation market alone worth $85 billion in 2022.   

Are All Galvanised Materials Hot-Dipped?

Hot dip galvanisation is just a specific type of galvanisation. Not all galvanised components are hot-dipped.

Other forms of galvanisation include:

  • Electro galvanising (Electroplating, zinc electro-deposition) – An electro current applies the zinc onto the surface.
  • Sherardising (Thermal Diffusion Galvanising) – The steel gets heated in a closed container with zinc powder.
  • Mechanical Galvanising (Centrifuge Galvanising) – Mixes steel with zinc powder and glass beads inside a drum or barrel.

While zinc is the abundant element used to galvanise metals like steel and iron, other metals can be used depending on their properties and the application of the material, such as aluminium, nickel, lead, and tin.

What is the Difference Between Galvanised and Hot Dipped Galvanised?

Hot dipped galvanising differs from other forms of galvanisation through the method and result. Firstly, the name “Hot dipped” refers to the process that immerses steel or iron in molten zinc. Secondly, hot dip galvanised components tend to be more rust-resistant than other types of galvanisation.

Due to this extra durability, hot dip galvanisation is a common choice for building and construction projects as the steel or iron can withstand more wear and tear.

What is the Hot Dip Galvanising Process?

Hot dip galvanising requires what’s known as a metallurgical bond between zinc and steel with a series of iron-zinc alloys. By submerging the component, you ensure that all areas get covered with a consistent finish.

The hot dip galvanising process involves the following stages:

1. Surface Preparation

Clean the steel or iron component using a caustic solution. This method removes any oil, grease, dirt or paint. Once cleaned, your component must be rinsed thoroughly so no caustic solution remains.

Your material should then be “pickled” within an acidic solution to remove any mill scale before repeating the same rinsing process.

Finally, you apply a flux, such as zinc ammonium chloride. This treatment helps the molten zinc stick to your material.

2. Galvanisation

Immerse your metal into the molten zinc heated at 450°C. Leave your metal inside the bath until the temperature of the steel or iron reaches the same as the zinc.

3. Quenching

Once immersed and the temperature has equilibrated, remove the component and allow it to cool in the air, where the pure zinc reacts with oxygen to form zinc oxide that reacts with carbon dioxide and forms zinc carbonate.

At this stage, the coating solidifies to ensure a well-bounded, robust and protected layer for your iron or steel.

4. Inspection

 A final inspection is necessary to assess whether the zinc coating has adhered to the surface and covers the entire area.

What Are the Benefits of Hot Dip Galvanisation?

Now we know the process and definitions, how about we investigate what makes hot dip galvanisation the most used method for coating materials in protective zinc?

Here are the seven benefits of hot dip galvanisation:

1. Corrosion Resistance

Hot dip galvanisation provides three elements to battle corrosion. These elements include the initial barrier, cathodic protection and zinc patina development. All three factors ensure hot dip galvanised products remain robust with durability and longevity for decades.

2. Cost-Effective

Hot dip galvanisation is a more affordable metal finishing solution compared with other alternatives. Beyond the initial fee, it’s the long-term, maintenance-free effects that serve hot dip galvanisation as a much more cost-effective option.

3. Longevity

Combining cost-effectiveness with protection, you have the remarkable longevity of hot dip galvanisation. A hot dip galvanised product can last over 50+ years.

4. Zero-Maintenance

Hot dip galvanising is self-maintaining by nature, and with its long-lasting effects, you can keep costs lower than other galvanised options or metal finish alternatives.

5. Complete Coverage

By defining the hot dip galvanisation process in the complete immersion of your material, this method means all areas get covered with a consistent layer of protection.

6. Versatility

The resulting protection from hot dip galvanisation suits multiple applications across construction, infrastructure, automotive, telecommunications and other industries.

7. Reliability

BS EN ISO 1461:2022 is the official UK standard for hot dip galvanisation to help all hot dip galvanised products and components meet specific regulations and quality standards.

Protect Your Products with High-Quality Hot Dip Galvanisation

At Barton International, we support businesses to commit to the longevity of their metal components with our hot dip galvanisation services. 

Beyond providing industry-leading metal fabrication services, we also offer the highest standards in metal finishes, ensuring your products or components stand the all-important test of time.

For more information on how our hot dip galvanising services can preserve your goods, get in touch and receive a free quote today.

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