The term “galvanize” has three different meanings, including, to stimulate with electricity, to make aware or rise to action, and “To coat (iron or steel) with rust-resistant zinc.” This is essentially what a hot-dip galvanized steel coils do, but there are certain aspects to the process that has been around for 150 years.
Corrosion happens to metal when air and moisture produce a chemical/electrochemical reaction with the environment that causes the metal to revert to its’ original ore state. Hot-dip galvanizers can protect metal against corrosion from happening by using hot zinc to dip the metal in.
Believe it or not, hot-dip galvanized coils are aware of the fact that metal must be submerged into the hot zinc for a specific amount of time for the process to protect the metal from corrosion. Since it is a 150-year-old practice, it is quite surprising that this machine can be so “smart” before all of the new smart technology was created.
How Does It Work?
The process covers the metal with zinc by making it hot enough to bubble, which helps the metal to be sufficiently coated with the zinc and it, helps the metal stay covered with the zinc after it is removed from the kettle and cooled. The zinc protects metal because instead of the natural elements of the environment causing the metal to corrode, the zinc seals the metal from even being exposed to the moisture and air that causes corrosion.
Metal that has undergone the process lasts a lot longer being protected from the zinc than the metal that did not go through this process. One example of the tremendous lasting effect of the hot-dip galvanizing process is found through the Brooklyn Bridge. When the bridge was built, there were over 14,000 miles of metal wires that were put through the hot-dip galvanizing process. A hundred years after the bridge was built, the bridge had to go through rehabilitation. However, the wires that had gone through the process were still in excellent condition.
Although the cost of galvanizing metal is prohibitive (about $280 billion annually), the price of going without this process is far too high. If metal were not put through the hot-dip galvanizers, there would be indirect costs to the public because of corrosion. The incidental damages of corrosion are; loss of productivity because of traffic delays, accidents (including fatality) because of rusted handrails and guardrails, and all the wasted time and energy not to mention materials to replace the metal that destroyed because they weren’t galvanized. So, the cost percentage of using the hot-dip galvanizer being at 3.2 percent would go up to almost 6 percent for the indirect cost of not using this process. It seems like the good more than outweighs the bad in this situation.
Pros of hot-dip galvanized coil.
Unlike paint, hot-dip galvanizing offers cathodic protection besides a strong metallurgical bond. Cathodic security is achieved by using zinc- a more easily corroded metal- on the metal surface. Technically, the electrons in the zinc will sacrifice themselves to prevent corrosion.
In hot-dip galvanizing, the zinc patina formed on the galvanized coating acts as an effective barrier; it wears off first, thus delaying the corrosion of the surface. This thin but hard film is another layer of protection that is not provided by any other rust prevention technique.
The process of galvanized steel coils is also less expensive but more effective when compared to other methods like metalizing and electroplate galvanizing. In metalizing, zinc in wire or powder form is sprayed onto the surface of the corrosive metal. Such an approach only results in a barrier (just like in case of paint coating) and limited cathodic protection. In electroplate galvanizing, zinc is electrochemically applied to the steel, but the layer formed in quite thin.
Hot rolled coils is a process that is widely used in many industrial applications. This is because the resulting coated steel or iron can be used in just the same way as the uncoated one. The galvanized steel can also be welded easily, provided you have taken precautionary measures for the zinc fumes. Galvanized steel is also ideal for high-temperature applications of up to 200-degree centigrade.