KnowledgeBase » Top Rated Questions

Is it safe for food to be in contact with galvanized steel?

For most foods, contact with galvanized steel is perfectly safe. Only acidic foods should not come in contact with galvanized steel according the the U.S. Food & Drug Administration. The acid in some foods reacts with the zinc coating to form salts that are readily absorbed by the body and in excess could cause a very mild sickness. So, where is galvanized steel used ...
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What does the cold galvanizing process consist of?

The term “cold galvanizing” is more of a marketing term than an actual process. Cold galvanizing is simply painting a piece of steel with zinc-rich paint. There are not tanks or preparation necessary other than the equipment you would need to paint any other material (blasting tools, spray guns or rollers, etc.). Because the coating is simply zinc-rich paint, it will ...
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Hot-Dip Galvanized Steel in Contact with Treated Wood

Pressure treated wood is often used for construction areas that will be exposed to the weather or in high moisture areas. The chemicals used to treat this wood have been revised in 2003 to remove some of the potential harmful elements in the pressure treatment. The change in chemical formulations has had a secondary effect on the corrosivity of the pressure tr...
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Measuring Zinc Coating Thickness of Hot-dip Galvanized Steel

Coating thickness is tested by using a magnetic thickness gauge. There are three types of magnetic thickness gauges: pencil-style, banana-style, and electronic. Electronic thickness gauges are the most common and the most accurate. Information on how to measure the thickness with magnetic gauges is contained in ASTM E376, and the minimum coatin...
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Required vent & drain holes for hollow structural sections & handrail tubing

In order to ensure that all interior and exterior surfaces are protected from corrosion, entire steel fabrications are lowered into and raised out of cleaning solutions, flux solutions, and molten zinc metal. In order to facilitate interior and exterior cleaning and coating, it is necessary to provide holes in fabrications to be galvanized. The primary reason for...
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Bare Spots

Bare spots, uncoated areas on the steel surface, can occur because of inadequate surface preparation. Bare spots may be caused by welding slag, sand embedded in castings, excess aluminum in the galvanizing kettle, or lifting devices that prevent coating formation in a small area. To avoid bare spots, (left) the galvanizer must ensure surfaces are cle...
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Coating Characteristics of Zinc-Rich Paint

Organic or inorganic zinc-rich paints are applied to a dry film thickness of 2.5 to 3.5 mils (64 to 90 µm). Organic zinc paints consist of epoxies, chlorinated hydrocarbons, and other polymers. Inorganic zinc paints are based largely on organic alkyl silicates. The zinc dust must be at a concentration high enough to provide for electrical conductivity in the dry film ...
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Clogged Holes

Clogged holes are a defect caused by molten zinc metal not draining adequately and partially or completely filling holes with excess zinc. Molten zinc will not drain easily from holes less than 3/10” (8mm) in diameter due to the viscosity of zinc metal. A good example is the screen shown to the right. Clogged holes can be minimized by making all holes as ...
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Preparing the hot-dip galvanized steel surface for painting or powder coating

Similar to painting over black steel, surface preparation is critical when painting or powder coating over the zinc coating of hot-dip galvanized steel. However, before any surface preparation takes place, the galvanizer should be notified the steel will be painted. With this understanding, the galvanizer will forego any post-treatments that could af...
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How does galvanized steel perform in seawater splash zones?

Splash zones are the most aggressive environment for hot-dip galvanized steel (or any other protective coating) because as the zinc coating reacts with the chlorides when wetted, zinc corrosion products are formed. Then those corrosion products dry and are later washed away when the steel is wetted again at which time more zinc corrosion products form. That process repeats its...
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