The benefit of using zinc in the preservation of iron and steel has been known since the early 1800's. Over the last 200 years the process has not changed significantly.
How does zinc work to safeguard ferrous metal?
Hot-dip galvanizing produces a coating resulting from a metallurgical reaction between the liquid zinc and iron in the steel.
The coating consists of four layers, three of which are zinc-iron alloys and the fourth (top layer) of pure zinc.
A strange synergy occurs when steel is galvanized. The three new layers formed (under the ETA, or pure zinc, layer) are actually harder than the original steel. (See zinc cross section below).
Typical coatings on structural steel will be in excess of four mils (mill = 1/1000").
The A.S.T.M. (American Society for Testing Materials) sets the specifications required for zinc thickness based on size and use of products.
On a properly galvanized piece of steel, in most atmospheric environments, one can expect the zinc to prevent corrosion of the substrate for 60-80 years.
The service life chart (shown below) provides the estimated life of a hot dip galvanized coating in different environments.
Note that the variation in life expectancy is directly related to the thickness of zinc on the metal.
At Korns galvanizing is conducted under controlled circumstances to ensure uniform coating and appearance. We conform to the A.S.T.M. standards and any agreed upon specific customer requirements.
Consistency in process results in consistency in product.
If you need uniformity of product, reliable turn around, experience and competitive pricing, we've been looking for you!