Ten important reasons to use Hot Dip Galvanization

1 Competitive initial costDue to the fact that it is a highly mechanical process, fire galvanization in main aplications has a lower initial cost compared to other anti-corrosive coatings.2 Lower maintenace costThe lower initial cost and durability makes hot dip galvanization more versatile and less espensive to protect steel and cast iron for longer periods against atmospheric corrosion. In equipment or structures located in areas of difficult access, mountains or still with security restrictions (e.g. electrification towers), the increasing maintenance...

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GREY COATINGS ON HOT DIP GALVANIZED STEEL

INTRODUCTIONA common phenomenon with hot dip galvanized structural steel is the grey appearance of part or all of the coating after galvanizing, where the expectation of the customer is for the galvanized steel to be shiny. Grey coatings are often a cause of contention between galvanizers and their customers as a result. This  File has been produced to explain the phenomenon of grey coatings, their cause and effect on the performance of hot dip galvanized steel.WHY ARE SOME GALVANIZED COATINGS...

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Typical Steps in the manufacturing process of Galvanizing

1) Cleaning: The step in which the majority of oil, grease, and paints, are removed with a hot alkaline cleaner.This cleaner usually consists of a lead bath or hot soapy water.2) Rinse/Air Flow: A bath of cooled water to rinse any of the cleaning residue off and air knives to aid in the removing of any additional residue and water that were used on the material before entering the pickling system .3) Pickling: A bath of diluted hydrochloric or sulfuric acid solutions that serve to remove surface...

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The typical characteristics of appearance:

There are several characteristics to the appearance to include; dull gray color, rust stains, blisters, texture(smooth, rough), lumps, pimples, bare spots, bulky white deposit, and dark spots. The following informationwill tell more about these different appearance issues:1. Dull gray coating: This type of coating is normally acceptable and is caused by growth of the zinc iron alloy layers through to the surface of the galvanized coating .2. Rust stains: The rust stains are acceptable when present...

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VENTING AND DRAINING - HOW TO GET THE HOLE SIZE RIGHT

One of the most common issues in designing fabrications for hot dip galvanizing is ensuring that fabrications are vented and drained correctly. All steel to be galvanized needs to be immersed in molten zinc and the zinc needs to be able to flow freely into and out of all hollow sections and corners. The flow of molten zinc into, off, and out of the fabrication is one of the most important factors in determining the final quality of the coating. Inadequate venting and draining can cause the following...

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HOT DIP GALVANIZE HYSTORY

History of HDGThe recorded history of galvanizing goes back to 1742 when a French chemist named P.J. Malouin, in a presentation to the French Royal Academy, described a method of coating iron by dipping it in molten zinc. In 1836, Stanilaus Tranquille Modeste Sorel, another French chemist, obtained a patent for a means of coating iron with zinc, after first cleaning it with 9% sulfuric acid and fluxing it with ammonium chloride. A British patent for a similar process was granted...

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Wet Storage Stain (White Stain/White Rust)

WET STORAGE STAIN(WHITE RUST/WHITE STAIN)Wet storage stain, also known as white rust, is the voluminous white or gray deposit formed by accelerated corrosion of the zinc coating when closely-packed, newly-galvanized articles are stored or shipped under damp and poorly ventilated conditions.It is found most often on stacked and bundled items, such as galvanized sheets, plates, angles, bars, and pipe. Weathered zinc surfaces which have already formed their normal protective layer of corrosion products...

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