What Is Galvanized Steel? Do My Vents Need It? (Answered)

If you’re working on your ventilation ducting system, you’ve probably heard the term galvanize steel a few times. But what is galvanized steel? 

Galvanized steel is steel that has undergone a treatment process with a protective zinc coating to prevent rust. 

But there is a lot more to it than that. So, in this article, we will cover what galvanized steel is, how it works, and why it’s important for your ventilation ductwork.

Editor’s note: This article has been updated on September 15, 2021, to include additional information regarding galvanization.

What is Galvanized Steel?

Galvanized steel is a metal that has gone through the galvanization process. The galvanization process is the process of adding a thin coat of zinc to different types of metals. Different methods are used to galvanize metal, including pre-galvanizing, electrogalvanizing, and hot dipping.

Why should I use galvanized steel for ductwork?

Galvanized steel is the most often utilized material for duct construction. The zinc coating on this material helps prevent corrosion and rust buildup. Additionally, its adaptability enables fabricators to create ducts in a variety of shapes to fulfill specific installation requirements.

Ducts constructed of galvanized steel are always wrapped in duct wrap to assist minimize noise and prevent the loss of cold or hot air that would occur in the absence of insulation. 

How does galvanizing protect the metal?

Below are some of the advantages of galvanizing metal.

1. The zinc coating keeps corrosive chemicals such as acid (for example, acid rain) from accessing the metal beneath.

2. Galvanization prevents corrosion. Even if the coating is scratched, the zinc coating will still “sacrifice its anode” easier than the base metal, preventing corrosion.

3. Zinc protects the base metal by corroding quicker than the base metal. The galvanized metal is sometimes treated with a substance called a “chromate,” which increases the corrosion rate. Even though it seems like you would not want this to happen, it’s actually protecting the underline metal from corrosion.

Which metals can be galvanized?

Iron and steel are the two most frequently galvanized metals. However, several types of metal can be treated with this process.

Most iron-based metals can be galvanized, while most non-ferrous metals cannot. You can use a magnet to tell if a metal is ferrous or non-ferrous if you are uncertain. A magnetic object will stick to metal. If the magnet does not adhere, it’s a non-ferrous metal.

Some of the metals that can be galvanized include:

  • Cast iron, 
  • Malleable iron 
  • Cast steels
  • Hot-rolled steel
  • Cold-rolled steels 
  • Weathering steel 
  • 300 series Stainless steel

What are the patterns on galvanized Steel?

When metal is galvanized, the zinc creates a characteristic pattern on the metal known as “spangle.” The spangles are very unique and give the steel an interesting look.

What Is the origin of the word “galvanize”?

The term “galvanization” is derived from the name of the Italian scientist Luigi Galvani. Today, the phrase “galvanize” usually refers to the process of covering base metals with zinc, but it was originally used to indicate “providing electric shocks.”

Luigi Galvani researched “bioelectricity,”. He was interested in the human nervous system, and how to generate and respond to electrical patterns. When he shocked a dead frog’s limb with an electrical spark, the muscles twitched, and he realized that bodies generate electricity.

What is the galvanization process?

There are three main methods of galvanizing metal:

  • The hot-dip method
  • Electrogalvanization method
  • Pre galvanizing method

1. The hot-dip method 

This galvanization procedure forms a beautiful, thick layer of zinc on top of the base metal, making it extremely corrosion resistant. The hot-dip method doesn’t cause structural integrity to be compromised in most instances, however, hydrogen embrittlement can sometimes occur in high-strength steels.

The steel used in automobile bodies is galvanized as well, but a separate galvanization method is employed because decorative paint coats must be placed afterward. This is due to the hot-dip method’s very thick zinc coating, which interferes with paint adhesion. To remedy this, Automobiles manufacturers use the electro galvanization process. 

2. Electrogalvanization method

The electrogalvanized automobiles manufacturers use, on the other hand, the electro galvanization process.  A tank is filled with a solution of saltwater (saline) and zinc, and the steel or base metal is dipped inside. A current is passed across the vat, and the zinc bonds to the base metal!

3. Pre-galvanizing

This method varies according to the galvanized component’s nature. Generally, steel components are immersed for a brief length of time in a “galvanizing bath” of molten zinc. Excess zinc is removed from the steel when it is taken from the bath using a mechanical wiper, an air knife, or steam. This results in somewhat thin zinc galvanized coating.

If love to see how things are made, take a look at this video from ColonialWebb covers how galvanized steel ductwork is made.

How It’s Made: Ductwork – Behind the Yellow Tape by ColonialWebb.

Conclusion

If you are considering new ductwork, consider galvanized steel. It’s inexpensive, corrosion-resistant.

In this post, we covered what galvanized steel is, how it’s made, and why you might want to use it in your ventilation system. Here are some key takeaways:

Key takeaways:

  • Galvanized steel is has a coat of zinc to prevent corrosion
  • GalvanizedDucts can be insulated to reduce noise ductwork can be 
  • The patterson galvanized steel are called spangles
  • The most common method of galvanizing is called hot dipping

If you’d like to learn more about range hoods, check out our full blog here. Stay safe!

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