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A hot-dip galvanized coating is relatively easier and cheaper to specify than an organic paint coating of equivalent corrosion protection performance. The
British, European and International standard for hot-dip galvanizing is BS EN ISO 1461, which specifies a minimum coating thickness to be applied
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Like other corrosion protection systems, galvanizing protects steel by acting as a barrier between steel and the atmosphere. However, zinc is a more electropositive (active) metal in comparison to steel. This is a unique characteristic for galvanizing, which means that when a galvanized coating is
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In some cases, it may be desirable to have designates parts of the metal as non-galvanized. This is often desired when metal will be welded after galvanization. To accomplish this, a galvanizer will typically use a masing compound to coat the areas that will not be galvanized during the hot dip
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easier and protect the kettle from uneven heat distribution from the burners. Environmental regulations in the United States disapprove of lead in the kettle bath. Lead is either added to primary Z1 grade zinc or already contained in used secondary zinc. A third, declining method is to use low Z5
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Further performance and design information for galvanizing can be found in BS EN ISO 14713-1 and BS EN ISO 14713-2. The durability performance of a galvanized coating depends solely on the corrosion rate of the environment in which it is placed. Corrosion rates for different environments can be
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Galvanized steel can be welded; however, one must exercise caution around the resulting toxic zinc fumes. Galvanized fumes are released when the galvanized metal reaches a certain temperature. This temperature varies by the galvanization process used. In long-term, continuous exposure, the
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Steel strip can be hot-dip galvanized in a continuous line. Hot-dip galvanized steel strip (also sometimes loosely referred to as galvanized iron) is extensively used for applications requiring the strength of steel combined with the resistance to corrosion of zinc, such as
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recommended maximum temperature for hot-dip galvanized steel is 200 °C (392 °F), according to the
American Galvanizers Association. The use of galvanized steel at temperatures above this will result in peeling of the zinc at the
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is often used in automotive manufacturing to enhance the corrosion performance of exterior body panels; this is, however, a completely different process which tends to achieve lower coating thicknesses of zinc.
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The process of hot-dip galvanizing results in a metallurgical bond between zinc and steel, with a series of distinct iron-zinc alloys. The resulting coated steel can be used in much the same way as uncoated.
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is applied to the steel to inhibit oxidation of the cleaned surface upon exposure to air. The flux is allowed to dry on the steel and aids in the process of the liquid zinc wetting and adhering to the steel.
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to steel in relation to the steels section thickness e.g. a steel fabrication with a section size thicker than 6 mm shall have a minimum galvanized coating thickness of 85
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is often added to the molten zinc bath to improve the fluidity of the bath (thus limiting excess zinc on the dipped product by improved drainage properties), help prevent floating
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gates, can be hot-dip galvanized by a process called batch galvanizing. Other modern techniques have largely replaced hot-dip for these sorts of roles. This includes
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in a bath of molten zinc at a temperature of around 450 °C (842 °F). When exposed to the atmosphere, the pure zinc (Zn) reacts with oxygen (
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found in BS EN ISO 14713-1, where typical corrosion rates are given, along with a description of the environment in which the steel would be used.
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The steel is cooled in a quench tank to reduce its temperature and inhibit undesirable reactions of the newly formed coating with the atmosphere.
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380:, for whom galvanizing was named, discovered the electrochemical process that takes place between metals during an experiment with frog legs.
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The steel is dipped into the molten zinc bath and held there until the temperature of the steel equilibrates with that of the bath.
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furthered the research on galvanizing when he discovered the electro-potential between two metals, creating a corrosion cell.
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European
Commission, Reference Document on Best Available Techniques in the Non Ferrous Metals Industries, December 2001
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damaged and steel is exposed to the atmosphere, zinc can continue to protect steel through
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Steel strip coming out of the zinc pot of a continuous vertical hot-dip galvanizing line
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338:. Galvanised steel is also used in most heating and cooling duct systems in buildings
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Protective effect: completely rusted letter box mounted to a hot-dip galvanized wall
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Crystalline surface of a hot-dip galvanized handrail, known as "spangle"
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525:"GalvInfoNote / The Spangle on Hot-Dip Galvanized Steel Sheet"
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described a method of coating iron by dipping it in molten
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A typical hot-dip galvanizing line operates as follows:
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patterning on the surface (often called a "spangle").
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obtained a patent for a method of coating iron with
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Individual metal articles, such as steel girders or
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solution. This removes oil/grease, dirt, and paint.
60:. Unsourced material may be challenged and removed.
398:, after first cleaning it with 9% sulfuric acid (
27:Process of coating iron or steel with molten zinc
373:in a presentation to the French Royal Academy.
198:), which further reacts with carbon dioxide (
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559:. V&S Hot Dip Galvanzing. Archived from
353:, forming a thinner and much stronger bond.
279:The caustic cleaning solution is rinsed off.
120:Learn how and when to remove this message
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220:is widely used in applications where
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293:The pickling solution is rinsed off.
58:adding citations to reliable sources
584:Primary zinc grade table on page 15
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557:"The Hot-Dip Galvanizing Process"
286:in an acidic solution to remove
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171:. It is the process of coating
45:needs additional citations for
224:is needed without the cost of
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470:– galvanization and annealing
413:it with ammonium chloride (
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530:. GalvInfo. Archived from
479:Liquid metal embrittlement
463:Corrugated galvanised iron
458:Bolt manufacturing process
205:) to form zinc carbonate (
272:Steel is cleaned using a
523:GalvInfo (August 2011).
390:In 1836, French chemist
365:In 1742, French chemist
216:in many circumstances.
69:"Hot-dip galvanization"
302:zinc ammonium chloride
194:) to form zinc oxide (
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165:Hot-dip galvanization
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601:Corrosion prevention
448:Electrogalvanization
367:Paul Jacques Malouin
222:corrosion resistance
136:Galvanised hand rail
54:improve this article
332:roofing and walling
18:Hot-dip galvanizing
347:electrogalvanizing
254:galvanic corrosion
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499:Surface finishing
494:Sendzimir process
242:Electrogalvanized
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565:. Retrieved
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468:Galvannealed
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52:Please help
47:verification
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541:27 February
357:process.
245:sheet steel
595:Categories
567:2012-11-30
510:References
288:mill scale
80:newspapers
474:Jewelling
383:In 1801,
376:In 1772,
323:recycling
214:corrosion
606:Coatings
442:See also
300:, often
453:Plating
411:fluxing
361:History
284:pickled
274:caustic
260:Process
240:layer.
94:scholar
409:) and
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535:(PDF)
528:(PDF)
336:pails
319:dross
185:metal
179:with
177:steel
101:JSTOR
87:books
611:Zinc
543:2014
396:zinc
371:zinc
315:Lead
298:flux
207:ZnCO
181:zinc
175:and
173:iron
73:news
421:).
196:ZnO
56:by
597::
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432:μm
419:Cl
415:NH
404:SO
296:A
200:CO
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417:4
406:4
402:2
400:H
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209:3
202:2
191:2
189:O
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