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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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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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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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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Repairing damaged or uncoated areas of hot-dip galvanized coatings

Although galvanized coatings are highly abrasion resistant, coating damage may occur once the galvanized steel leaves the galvanizer’s facility due to extremely rough handling, installation techniques, or in-service conditions. Occasionally, small areas of the galvanized article may be bare due to unseen contaiminants the cleaning process is unable to remove. There are methods available to ensure post-galvanizing coating integrity and ASTM A78...
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Why paint over galvanizing may fail

Paint failure mechanisms are somewhat complex when paint is applied over hot-dip galvanized steel, otherwise known as a duplex system, and they may be manifested as peeling, flaking, or blisters. And regardless of the age of the galvanized steel (new, partially weathered, fully weathered), the cause is either inadequate surface preparation or using a paint/powder coat system not compatible with zinc. First, let’s examine inadequate surface pre...
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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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What steel products are covered by ASTM A123?

The specification covers the requirements for zinc coatings by the hot-dip galvanizing process on iron and steel products, both unfabricated and fabricated. This includes but is not limited to assembled steel products, structural steel fabrications, bent or welded tubes, wire work, grating, expanded metal, pipe, handrail. It also covers steel forgings and iron castings. It does no...
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