What is hot-dip galvanizing process?

What is hot-dip galvanizing process?

Hot-dip galvanizing is the process of immersing iron or steel in a bath of molten zinc to produce a corrosion resistant, multi-layered coating of zinc-iron alloy and zinc metal. While the steel is immersed in the zinc, a metallurgical reaction occurs between the iron in the steel and the molten zinc.

What are the three steps in hot dipped steel galvanizing?

The hot-dip galvanizing process consists of three steps: surface preparation, galvanizing, and inspection. Surface Preparation: For high quality hot-dip galvanizing, steel must be properly prepared prior to being immersed in a bath of molten zinc.

What is the purpose of hot-dip galvanizing?

Hot dip galvanizing is a process developed to prevent steel from corroding. Before the process can take place, the steel goes through a thorough chemical clean which removes all rust, oil and mill scale from the surface. When the cleaning solution has been rinsed off, the coating process can begin.

Does galvanizing weaken steel?

Hot-dip galvanizing Vehicle bodies do not need a very thick layer of zinc because the manufacturer also adds coats of paint. In most cases, hot-dip galvanizing does not weaken the steel on a measurable scale. However, hot-dip galvanizing of high-strength steels can result in hydrogen embrittlement.

How does Galvanising prevent rusting?

Galvanising is a method of rust prevention. The iron or steel object is coated in a thin layer of zinc. This stops oxygen and water reaching the metal underneath – but the zinc also acts as a sacrificial metal . Zinc is more reactive than iron, so it oxidises in preference to the iron object.

What are the steps of galvanizing?

Galvanizing steel consists of just three steps: Surface Preparation….Surface Preparation

1. Degreasing/Caustic Cleaning. An acidic “bath” removes organic contaminants from the steel surface.
2. Picking. A dilute solution of acid is used to remove mill scale and rust from the steel.
3. Fluxing.

How is Galvanising done?

The hot dip galvanizing process is relatively simple. It involves cleaning steel and immersing it in molten zinc to obtain a coating. Hot dip galvanizing is the process of coating iron or steel with a layer of zinc by immersing the metal in a bath of molten zinc at a temperature of around 450 °C (842 °F).

How long does hot-dip galvanizing last?

A key benefit of using Hot Dip Galvanizing is its durability. Data shows that galvanizing can provide between 34 to 170 years of protection for steel.

What are the steps in the hot dip galvanizing process?

There are three fundamental steps in the hot-dip galvanizing process; surface preparation, galvanizing, and inspection ( Figure 1 ). When the fabricated steel arrives at the galvanizing facility, it is hung by wire or placed in a racking system which can be lifted and moved through the process by overhead cranes.

Why is hot dip galvanized steel used for corrosion protection?

Metals toward the top of the list are “less noble” and have a greater tendency to lose electrons than metals found lower on the list. Utilizing hot-dip galvanized steel exploits this phenomenon by sacrificing zinc (anode) to protect the underlying steel (cathode).

Why is surface preparation important in the galvanizing process?

The surface preparation step in the galvanizing process has its own built-in means of quality control because zinc simply will not react with unclean steel.

What’s the best way to hang hot dip articles?

For long, straight sections, 2 lifting lugs are preferred to avoid wire or chain marks. Where possible, articles are hung on a 45° angle (approximately) to ensure efficient drainage of pre-treatment solutions and molten zinc. This avoids rough surfaces and lets the air escape from the highest point, preventing explosions.