First of all let us get through a bit of history:
Galvanizing is the action of covering a part with a layer of zinc in order to protect it against corrosion. The treatment is said to be anticorrosive. The word comes from the name of the inventor Luigi Galvani (1737-1798), an Italian physicist and doctor who discovered galvanism on November 6, 1780.
In industry, this term essentially refers to “hot-dip galvanizing” processes.
The first patents for hot-dip galvanizing (by dipping all the elements) date from the 1840s. French engineer Stanislas Sorel obtained a patent1 on May 10, 1837 for this hot-dip galvanizing method2.
In 1837, the naturalized Russian German physicist and engineer Moritz Hermann von Jacobi discovered electroplating in Saint Petersburg. In 1854, the industrialist and chemist Léopold Oudry created an electrochemical workshop. He succeeded in permanently coppering small parts, then by modifying his process he obtained the order for galvanic copper plating of all cast iron objects and monuments.
In industry, this term essentially refers to “hot-dip galvanizing” processes.
The first patents for hot-dip galvanizing (by dipping all the elements) date from the 1840s. French engineer Stanislas Sorel obtained a patent1 on May 10, 1837 for this hot-dip galvanizing method2.
In 1837, the naturalized Russian German physicist and engineer Moritz Hermann von Jacobi discovered electroplating in Saint Petersburg. In 1854, the industrialist and chemist Léopold Oudry created an electrochemical workshop. He succeeded in permanently coppering small parts, then by modifying his process he obtained the order for galvanic copper plating of all cast iron objects and monuments.
What do we mean by Hot Dip Galvanzing:
Hot dip galvanizing is the process of coating mild steel by submerging it into molten zinc for the purpose of protecting it against corrosion.
The most cost effective, simple and durable way of beating the rust is hot dip galvanizing. The reason that hot dip galvanizing is the most durable coating for steel is that the molten zinc actually bonds with the steel during the galvanizing process creating zinc-iron alloy layers of protection that are harder than the steel itself and will not rust. So, unlike paint, the galvanized coating does not merely sit on top of but becomes a part of the steel itself.
Mild steel is a strong and relatively cheap material for use in a variety of industries and a host of applications from tiny brackets to large structural beams. The one major problem with it is its tendency to rust.
The British Standard for Hot Dip Galvanizing is BS EN ISO 1461:2009 (Hot dip galvanized coatings on fabricated iron and steel articles) and covers the general properties and testing methods of hot dipping steel in zinc.
The most cost effective, simple and durable way of beating the rust is hot dip galvanizing. The reason that hot dip galvanizing is the most durable coating for steel is that the molten zinc actually bonds with the steel during the galvanizing process creating zinc-iron alloy layers of protection that are harder than the steel itself and will not rust. So, unlike paint, the galvanized coating does not merely sit on top of but becomes a part of the steel itself.
Mild steel is a strong and relatively cheap material for use in a variety of industries and a host of applications from tiny brackets to large structural beams. The one major problem with it is its tendency to rust.
The British Standard for Hot Dip Galvanizing is BS EN ISO 1461:2009 (Hot dip galvanized coatings on fabricated iron and steel articles) and covers the general properties and testing methods of hot dipping steel in zinc.
Our Galvanizing Process:
Surface preparation consists of three steps:
Degreasing: - A hot alkali solution, mild acidic bath, or biological cleaning bath removes organic contaminants such as dirt, paint markings, grease, and oil from the metal surface. Epoxies, vinyls, asphalt, or welding slag, which cannot be removed by degreasing, must be removed before galvanizing by grit-blasting, sand-blasting, or other mechanical means.
Pickling: A dilute solution of heated sulfuric acid or ambient hydrochloric acid removes mill scale and iron oxides (rust) from the steel surface. As an alternative to or in conjunction with pickling, this step can also be accomplished using abrasive cleaning or air blasting sand, metallic shot, or grit onto the steel
Fluxing:The final surface preparation step, a zinc ammonium chloride solution, serves two purposes. It removes any remaining oxides and deposits a protective layer on the steel to prevent any further oxides from forming on the surface prior to immersion in the molten zinc.
Galvanzing: The “galvanizing” step of the process occurs when steel is completely immersed in a bath (kettle) of molten zinc. According to specification, the bath chemistry must be at least 98% pure zinc and maintained at a temperature approximately 840 F (449 C). The steel is lowered at an angle by crane hoist. This allows air to escape from tubular shapes or pockets that may be within the design of a fabricated piece and of course permits the molten zinc to displace the air. While immersed in the kettle, the zinc reacts with iron in the steel to form a series of zinc-iron inter-metallic alloy layers. Once the fabricated item reaches bath temperature the coating growth is complete, and the articles are withdrawn slowly from the galvanizing bath. Excess zinc is removed by draining, vibrating, and/or centrifuging. The metallurgical reaction will continue after withdrawal from the bath, as long as the article remains near bath temperature. Articles are cooled either by immersion in a passivation solution or water or by being left in open air.
Inspection: The last phase of the process, inspection, is simple and quick. The two properties of the hot-dip galvanized coating closely scrutinized are coating thickness and coating appearance. There are additional tests outlined for adherence, but these are typically only administered as a “referee” test, or when an issue is suspected.A very accurate determination as to the quality of the galvanized coating can be accomplished through a visual inspection of the material, because as stated earlier zinc will not react with unclean steel. A variety of simple physical and laboratory tests may also be performed to determine thickness, uniformity, adherence, and appearance to ensure the coating is in compliance with specification requirements. Products are galvanized according to long established, accepted, and approved standards of ASTM.
Degreasing: - A hot alkali solution, mild acidic bath, or biological cleaning bath removes organic contaminants such as dirt, paint markings, grease, and oil from the metal surface. Epoxies, vinyls, asphalt, or welding slag, which cannot be removed by degreasing, must be removed before galvanizing by grit-blasting, sand-blasting, or other mechanical means.
Pickling: A dilute solution of heated sulfuric acid or ambient hydrochloric acid removes mill scale and iron oxides (rust) from the steel surface. As an alternative to or in conjunction with pickling, this step can also be accomplished using abrasive cleaning or air blasting sand, metallic shot, or grit onto the steel
Fluxing:The final surface preparation step, a zinc ammonium chloride solution, serves two purposes. It removes any remaining oxides and deposits a protective layer on the steel to prevent any further oxides from forming on the surface prior to immersion in the molten zinc.
Galvanzing: The “galvanizing” step of the process occurs when steel is completely immersed in a bath (kettle) of molten zinc. According to specification, the bath chemistry must be at least 98% pure zinc and maintained at a temperature approximately 840 F (449 C). The steel is lowered at an angle by crane hoist. This allows air to escape from tubular shapes or pockets that may be within the design of a fabricated piece and of course permits the molten zinc to displace the air. While immersed in the kettle, the zinc reacts with iron in the steel to form a series of zinc-iron inter-metallic alloy layers. Once the fabricated item reaches bath temperature the coating growth is complete, and the articles are withdrawn slowly from the galvanizing bath. Excess zinc is removed by draining, vibrating, and/or centrifuging. The metallurgical reaction will continue after withdrawal from the bath, as long as the article remains near bath temperature. Articles are cooled either by immersion in a passivation solution or water or by being left in open air.
Inspection: The last phase of the process, inspection, is simple and quick. The two properties of the hot-dip galvanized coating closely scrutinized are coating thickness and coating appearance. There are additional tests outlined for adherence, but these are typically only administered as a “referee” test, or when an issue is suspected.A very accurate determination as to the quality of the galvanized coating can be accomplished through a visual inspection of the material, because as stated earlier zinc will not react with unclean steel. A variety of simple physical and laboratory tests may also be performed to determine thickness, uniformity, adherence, and appearance to ensure the coating is in compliance with specification requirements. Products are galvanized according to long established, accepted, and approved standards of ASTM.
Kettle Size:
Our Galvanizing kettle is 7.5 M/1.6M/2.5 M, however. we are able to galvanize materials up to 8 meters on Double immersion in length and up to 4.8 meters on double immersion in depth.
Why Should You Galvanize?
CORROSION PERFORMANCE
The level of Sulphur dioxide (SO2) in any particular environment usually determines the atmospheric corrosion of zinc. Over recent decades pollution has reduced resulting in much lower levels of SO2 in the UK. Taking the UK as an example in which Studies have shown that the atmospheric zinc corrosion rate in the country is usually between 0.5 to 2 microns per year.
A 6mm thick galvanized section, for example, should achieve an average minimum zinc coating of 85 microns (to conform to the British standard). Therefore, the galvanized coating on a 6mm thick section should last between 42.5 and 170 years.
Other localised factors such as humidity, chemicals, salt and proximity to other building materials, etc will influence corrosion rates too so if you require an approximate design life for the galvanized coating on your fabrication then please contact us for more details.
For very aggressive environments a thicker zinc coating can be achieved by grit blasting steelwork before galvanizing. This process can potentially increase the coating life by up to around 65%.
PHYSICAL PERFORMANCE
Hot dip galvanizing is simple and effective. Unlike paint systems, the galvanizing process actually bonds the zinc with the steel to form a coating that is very durable. Galvanized steel is therefore quicker and easier to transport, handle and erect with much less risk of damage on site. The physical performance of a galvanized coating is primarily down to the hard layers of zinc-iron alloys that form during the dipping process. These zinc-iron alloys form underneath the outer shiny zinc layer of the coating and are often even harder than the steel itself.
COMPLETE PROTECTION
The ‘dip’ in hot dip galvanizing is the key word here. Galvanizers dip the steel into molten zinc and so all surfaces of your fabrications, both inside and out, are coated and therefore protected. Other sprayed coatings can only coat those areas that can be seen and accessed. Rusting can occur on the inside surfaces of a fabrication just as easily as the outer but with hot dip galvanizing you can rest assured that this is not an issue.
MAINTENANCE FREE?
A bold statement and one that does need clarification, perhaps ‘maintenance freer’ would be more accurate (if not grammatically correct). In addition to the natural physical and corrosion resistance of a galvanized coating it also offers another benefit. Scratches in a painted coating will require immediate maintenance to seal the damaged area and prevent rust creeps under the surrounding paint. Zinc however, corrodes in preference to steel and therefore sacrifices itself to protect the steel. These corrosion products will deposit on the exposed steel resealing it from the atmosphere and thus helping to prevent further corrosion.
SUSTAINABLE (RECYCLABLE)
If it is accepted that mankind needs steel (to make its endless appetite for machinery and buildings etc) and that steel needs to be protected from corrosion, what better sustainable solution to use than zinc. Zinc is a naturally occurring and recyclable substance that is not harmful to us (remember that our bodies actually need a small amount of zinc to live healthily) and helps steel last a very long time.
Vulnerable steelwork that is not galvanized will require much more maintenance and will need replacing much sooner. A combination of regular maintenance and shorter life cycle will generate quite a carbon footprint.
The level of Sulphur dioxide (SO2) in any particular environment usually determines the atmospheric corrosion of zinc. Over recent decades pollution has reduced resulting in much lower levels of SO2 in the UK. Taking the UK as an example in which Studies have shown that the atmospheric zinc corrosion rate in the country is usually between 0.5 to 2 microns per year.
A 6mm thick galvanized section, for example, should achieve an average minimum zinc coating of 85 microns (to conform to the British standard). Therefore, the galvanized coating on a 6mm thick section should last between 42.5 and 170 years.
Other localised factors such as humidity, chemicals, salt and proximity to other building materials, etc will influence corrosion rates too so if you require an approximate design life for the galvanized coating on your fabrication then please contact us for more details.
For very aggressive environments a thicker zinc coating can be achieved by grit blasting steelwork before galvanizing. This process can potentially increase the coating life by up to around 65%.
PHYSICAL PERFORMANCE
Hot dip galvanizing is simple and effective. Unlike paint systems, the galvanizing process actually bonds the zinc with the steel to form a coating that is very durable. Galvanized steel is therefore quicker and easier to transport, handle and erect with much less risk of damage on site. The physical performance of a galvanized coating is primarily down to the hard layers of zinc-iron alloys that form during the dipping process. These zinc-iron alloys form underneath the outer shiny zinc layer of the coating and are often even harder than the steel itself.
COMPLETE PROTECTION
The ‘dip’ in hot dip galvanizing is the key word here. Galvanizers dip the steel into molten zinc and so all surfaces of your fabrications, both inside and out, are coated and therefore protected. Other sprayed coatings can only coat those areas that can be seen and accessed. Rusting can occur on the inside surfaces of a fabrication just as easily as the outer but with hot dip galvanizing you can rest assured that this is not an issue.
MAINTENANCE FREE?
A bold statement and one that does need clarification, perhaps ‘maintenance freer’ would be more accurate (if not grammatically correct). In addition to the natural physical and corrosion resistance of a galvanized coating it also offers another benefit. Scratches in a painted coating will require immediate maintenance to seal the damaged area and prevent rust creeps under the surrounding paint. Zinc however, corrodes in preference to steel and therefore sacrifices itself to protect the steel. These corrosion products will deposit on the exposed steel resealing it from the atmosphere and thus helping to prevent further corrosion.
SUSTAINABLE (RECYCLABLE)
If it is accepted that mankind needs steel (to make its endless appetite for machinery and buildings etc) and that steel needs to be protected from corrosion, what better sustainable solution to use than zinc. Zinc is a naturally occurring and recyclable substance that is not harmful to us (remember that our bodies actually need a small amount of zinc to live healthily) and helps steel last a very long time.
Vulnerable steelwork that is not galvanized will require much more maintenance and will need replacing much sooner. A combination of regular maintenance and shorter life cycle will generate quite a carbon footprint.
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Environment and Sustainability
Galvanizing has long been recognised as the most sustainable finishing process available to help the construction sector protect against corrosion, with the recent emergence of a number of technological advances making the procedure even more environmentally-friendly.
Hot dip galvanizing provides highly effective, durable and sustainable corrosion protection wherever steel is in use, from the structural steelwork used as the framework for major building projects, right through to final flourishes such as gates and railings.
As steel is highly prone to rust – it’s estimated that worldwide, one tonne of steel turns to rust every 90 seconds – it is essential that the life of steel components is protected from corrosion for as long as possible. Hot dip galvanizing protects from rusting. Clean steel components are immersed in molten zinc at a temperature of around 450 degrees until the temperature of the work is the same as the zinc. During this process a series of zinc-iron alloy layers are formed by a metallurgical reaction between the iron and the zinc. As work is removed from the zinc, the zinc on its surface will begin to solidify, as this happens excess zinc is removed to ensure a smooth finish.
In contrast with other finishes or protective coatings, hot dip galvanizing results in minimal waste.
Both the zinc ash produced from surface oxidation in the galvanizing bath and the ‘dross’ – a mixture of zinc and iron that accumulates at the bottom of the bath – are fully recovered and are often used in the same galvanizing process, or sold to make zinc dust and compounds for a variety of applications such as rubber additives, cosmetics and electronic components.
This means there is no loss of materials that may occur during the spray application of other coating types, and these processes – combined with the long life and recyclability of zinc-coated steel – make hot dip galvanizing a highly resource-efficient and sustainable process with minimal environmental impact.
Hot dip galvanizing provides highly effective, durable and sustainable corrosion protection wherever steel is in use, from the structural steelwork used as the framework for major building projects, right through to final flourishes such as gates and railings.
As steel is highly prone to rust – it’s estimated that worldwide, one tonne of steel turns to rust every 90 seconds – it is essential that the life of steel components is protected from corrosion for as long as possible. Hot dip galvanizing protects from rusting. Clean steel components are immersed in molten zinc at a temperature of around 450 degrees until the temperature of the work is the same as the zinc. During this process a series of zinc-iron alloy layers are formed by a metallurgical reaction between the iron and the zinc. As work is removed from the zinc, the zinc on its surface will begin to solidify, as this happens excess zinc is removed to ensure a smooth finish.
In contrast with other finishes or protective coatings, hot dip galvanizing results in minimal waste.
Both the zinc ash produced from surface oxidation in the galvanizing bath and the ‘dross’ – a mixture of zinc and iron that accumulates at the bottom of the bath – are fully recovered and are often used in the same galvanizing process, or sold to make zinc dust and compounds for a variety of applications such as rubber additives, cosmetics and electronic components.
This means there is no loss of materials that may occur during the spray application of other coating types, and these processes – combined with the long life and recyclability of zinc-coated steel – make hot dip galvanizing a highly resource-efficient and sustainable process with minimal environmental impact.
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🌿🏗️ Introducing the Colors of Sustainability in Our Galvanizing Production Workshop! 🌍🛡️
We're thrilled to share an exciting update about our galvanizing production workshop. Our commitment to protecting both steel and the environment is now reflected in the colors that surround us.
The harmonious blend of green and grey throughout our workshop symbolizes our dedication to environmental responsibility. Galvanizing isn't just about protecting the steel; it's also about preserving the world around us. By choosing these colors, we're showcasing our promise to reduce the impact of corrosion, extend the life of steel, and promote sustainable practices.
Green, a color often associated with nature and renewal, embodies our effort to make choices that benefit our planet. Grey, representing strength and stability, mirrors the robust protection that our galvanizing process provides to steel structures, ensuring they withstand the test of time and environmental challenges.
As we continue to innovate and improve our galvanizing techniques, we're reminded of the role we play in fostering a greener future. Our team's dedication, coupled with these colors, signifies our unwavering commitment to a more sustainable world.
Thank you for being a part of this journey with us. Together, we're building a future where protection and environmental consciousness go hand in hand.
We're thrilled to share an exciting update about our galvanizing production workshop. Our commitment to protecting both steel and the environment is now reflected in the colors that surround us.
The harmonious blend of green and grey throughout our workshop symbolizes our dedication to environmental responsibility. Galvanizing isn't just about protecting the steel; it's also about preserving the world around us. By choosing these colors, we're showcasing our promise to reduce the impact of corrosion, extend the life of steel, and promote sustainable practices.
Green, a color often associated with nature and renewal, embodies our effort to make choices that benefit our planet. Grey, representing strength and stability, mirrors the robust protection that our galvanizing process provides to steel structures, ensuring they withstand the test of time and environmental challenges.
As we continue to innovate and improve our galvanizing techniques, we're reminded of the role we play in fostering a greener future. Our team's dedication, coupled with these colors, signifies our unwavering commitment to a more sustainable world.
Thank you for being a part of this journey with us. Together, we're building a future where protection and environmental consciousness go hand in hand.
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