Duncan Galvanizing Blog

Hot-Dip Galvanizing vs. Metallizing

Posted by Casey Shearns on Tue, Jun 29, 2021 @ 02:26 PM

Hot-dip galvanizing and metallizing are both great and effective ways to protect steel against corrosion. However, they do have some significant differences, and it’s important to know all the details before choosing a method for your project’s corrosion protection. We broke down the differences and the main pros and cons of each so you can make an educated choice.

Galvanizing vs. Metallizing

When metal is hot-dip galvanized, it is brought to a galvanizing plant. Here, the metal is cleaned, prepped, and then it is completely submerged into a kettle of molten zinc to form a uniform layer of corrosion protection by alloying with the steel. Thermal spray zinc, also known as metallizing, is the process of coating steel by transporting molten zinc by a gas stream to a properly prepared substrate. If you use metallizing, the zinc coating is sprayed directly onto the metal. Droplets cool, solidify and build up on the substrate into a laminar structure, forming a coating. Both of these methods have pros and cons.

Pros and Cons

One of the biggest benefits of using hot-dip galvanizing as opposed to metallizing is the ability to apply uniform protection, both on the inside and outside of the steel. The complete submersion process of hot-dip galvanizing allows for corrosion protection both inside and outside of the metal structure. With metallizing, for small diameter tubes, only the outside of the structure can be reached and the application could potentially be uneven, especially in corners. Therefore, hot-dip galvanizing is often the best choice for tubular metals or steel with a complicated shape because of the uniform protection it provides. Also, hot-dip galvanizing has a higher adhesion strength and abrasion resistance thanks to the metallurgical bond it creates between the steel and zinc. However, the somewhat rough surface the process of metallizing creates allows it to have a higher unprocessed slip coefficient, and allows paint to stick better to the surface of unprepared surfaces.  Also, in situations where the steel material is large and thin, metallizing is a ‘cold’ process and can prevent deflection.  A common guideline is to hot-dip galvanize material that does not have deflection concerns and fits into a kettle, and metallize those that don’t.

Another notable difference between the two is the location the process takes place. The hot-dip galvanizing process must take place inside a galvanizing plant, as the metal needs to be dipped in a specialized kettle, drained, and vented. With metallizing, the zinc coating can be applied at any location, with no draining or venting needed. This is a good option if the zinc coating needs to be applied on-site (referred to as field metallizing), or if the piece of metal being is too large to fit into a kettle. However, hot-dip galvanizing in a plant tends to be more economical all around.

Contact Duncan Galvanizing

Duncan Galvanizing is the Northeast’s premier hot-dip galvanizer, offering hot-dip galvanizing, factory applied powder and paint coatings, blasting, specification assistance and more. Contact us today at 617-389-8440 or fill out a contact form on our website.

Tags: Corrosion Protection

The Importance of Galvanizing Steel

Posted by Casey Shearns on Fri, Mar 26, 2021 @ 03:32 PM

 

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Utilizing a protective coating such as hot-dip galvanizing is incredibly important to protect steel against damage from corrosion and other sources. Damage to steel can cause impactful financial, aesthetic, and safety failures, so it’s crucial to specify a protective coating such as hot dip galvanizing if steel is being used. Important benefits of galvanizing include:  

Prevents Structural Failures

Structural failures due to corroded steel can be devastating. They can cause serious injuries, loss of life, public outcry, and overwhelming financial damage. Hot dip galvanizing offers outstanding steel corrosion protection that preserves the structural integrity and can help to ensure your steel stays safe for use for years to come. The tightly-bonded, abrasion resistant inter metallic layers provide an unmatched protection from corrosion.

Prevents Aesthetic Failures

Aesthetic failures, although not physically dangerous, can be damaging to the reputation of your business. A project with damage and corrosion can distract from the work put in and the beauty of the architecture, and send the wrong message about the quality of your work. Hot dip galvanizing is a fantastic way to keep your steel looking like-new, decades after project completion. It’s important to use a protective coating that will uphold the desired look of the steel used to prevent any unsightly corrosion, and lost opportunities for future work. Additionally, hot dip galvanizing is able to protect the aesthetics of even the most intricate of steel designs, and can even be used on artistic projects to preserve its original finish.

Saves Time & Money from Corrosion Costs

Corrosion can result in pricey and time-consuming maintenance. In fact, 659 billion dollars of structural damage have occurred in the US alone from corrosion, and can quickly create a financial burden for you. Galvanizing allows for years, sometimes decades before maintenance is required. This extended time without maintenance allows for significant life-cycle cost savings. Oftentimes, the initial cost is the life cycle cost, making galvanizing a great investment.

Additionally, the additional resources needed for extra maintenance can derail your environmental sustainability efforts. Quality protective coating can eliminate the need for the use of excess natural resources due to the need for constant maintenance.

Protection From Vandalism

Vandalism and graffiti can be costly if it cannot be easily removed from steel. Some finishes offer graffiti protection to ensure that your investment will not be permanently damaged by vandalism. This is particularly important to consider if you are building a structure in a high traffic area, such as public transportation. A finish with graffiti protection may be a good choice if your team is concerned about vandalism. If you utilize one of Duncan Colorgalv Plus coatings, you will have long lasting anti-graffiti protection.

Contact Duncan Galvanizing - Hot Dip Galvanizing in Everett, MA

Duncan Galvanizing is the Northeast’s trusted provider of hot-dip galvanizing (Duragalv), color galvanizing (Colorgalv) and more. Contact us today at (617) 389-8440 to get started or request a quote.

Tags: Corrosion Protection

Why Specify Galvanizing?

Posted by Casey Shearns on Tue, Mar 09, 2021 @ 04:46 PM

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Steel corrosion can be costly, dangerous, and unsightly.  It’s important to make sure the steel used in your project is utilizing an effective method for protection against corrosion, abrasion, and weather conditions. Hot dip galvanizing is the process of factory dipping of fabricated steel into a kettle of molten zinc with the goal of preventing this corrosion, and creating a steel product that stays structurally sound and aesthetically pleasing for years to come. Hot dip galvanizing is often the preferred method of corrosion protection for steel for a number of its unique benefits, including:

Durability & Corrosion Protection

First, hot dip galvanizing is a great investment because of its durability and protection from even the harshest environments. This protective zinc alloy becomes tightly bonded to the steel, creating a layered protection with a bond strength of around 3,600 psi. In addition to the corrosion protection in any environment, this alloy also provides excellent abrasion resistance that is harder than the steel, protecting it from any damage that might occur during the shipment or construction process. 

Additionally, hot dip galvanizing is the ONLY system that protects the steel on the inside and the outside. Ensuring that the inside of fabricated steel is galvanized can be crucial to the integrity and life of the steel.  Also, because the steel is completely submerged in our zinc bath, there is a uniform protection on the entirety of the fabricated steel, while other methods such as liquid coatings often cause the protective coating along the edges to be thinner. Utilizing hot dip galvanizing is the only process that ensures this complete and uniform protection for steel.

Cost

Hot dip galvanizing also has several cost benefits. The overall material and application generally costs less than other corrosion protection methods. It also can be completed in less time due to the factory immersion process, saving construction time costs as well.

It also has lifetime cost benefits, as hot dip galvanized steel requires much less maintenance over time. In this chart, you can see the impressive amount of time hot dip galvanizing protects the steel from corrosion before first maintenance is required. 

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Sustainability

Both zinc and steel are 100% recyclable, making hot dip galvanizing a very ‘green’ process. Zinc is natural, abundant, and essential to life. Therefore, the use of steel is not introducing any harmful substances into the environment. Zinc and steel can also be recycled to be used many times over in different projects, so even at the end of a building or structure’s life, that material can be used again. In fact, 30% of the world’s zinc supply is recycled. This way, you can ensure that the materials used will not create waste. Hot dip galvanizing also uses less natural resources and creates less harmful emissions into the atmosphere, contributing to the overall environmental friendliness of your construction job.

Availability & Versatility

Hot dip galvanized steel is both readily available and accessible, as well as versatile for a variety of projects. Steel of many different shapes and sizes can be galvanized. Because of the total immersion in the zinc bath, even intricate shapes can be fully galvanized and protected from corrosion. This makes hot dip galvanizing a great choice for steel components that have a unique or complicated shape.

Additionally, because galvanizing occurs factory in a controlled environment, the process can be completed in any weather conditions, while other processes can’t. This allows construction projects to move quicker when the galvanizing can be completed any day, any time of year. The average turnaround time for hot dip galvanized steel ready for use is about 3-5 days, quicker than many other processes.

Contact Duncan Galvanizing

Duncan Galvanizing is the Northeast’s trusted provider of hot dip galvanizing, color galvanizing, and more. Contact Howie Levine for help with specifications or Seth Dubinsky to request a quote at (617) 389-8440 or fill out an online form to get started. 

Tags: Corrosion Protection, Hot Dip Galvanizing, Duncan Galvanizing

Spotlight On Colorgalv

Posted by Howard Levine on Tue, Sep 30, 2014 @ 02:45 PM

Colorgalv by Duncan

Click each image for an enlarged view.

NOT Colorgalv!

Riverfront Fencing Hartford Connecticut

Colorgalv®. There is NO equal.
And this proves it!

The picture on the top was taken in December of 2003, almost 10 years after the fencing was installed. It still looks great!

The picture on the bottom, also taken in December of 2003, has only been installed since 1999, and it has failed completely.

The only similarities between these two installations is the location. They are adjacent to each other on the Connecticut River.

Why would one fail and the other look as good as new 10 years later? The answer is simple: The installation on the top was Colorgalv® by Duncan. The one on the bottom was an “or equal”. Even though Colorgalv® was specified for the fencing on the bottom, the contractor submitted an “or equal”.

Why accept a substitution?
Is it cheaper? No. Is it better? No. Will it last longer? No.

The initial cost of Colorgalv® is virtually equal to painting over galvanizing, so there really is no appreciable “first cost” savings by going with an “or equal”. And when you look at life cycle costing, well, the savings are astronomical.

Colorgalv® is a complete process. All work is done in one factory controlled environment. Nothing is left to chance and all the variables that could possibly lead to a failure have been eliminated. So, Colorgalv® is truly a better process than an “or equal”.

And, since Colorgalv® is warranteed for 20 years, you will have the peace of mind knowing that a company in business since 1890 will be standing behind the work to ensure the longevity of the installation.

Contact Duncan Galvanizing

Want more information? Call Duncan at 617-389-8440 or email info@duncangalvanizing.com.

Tags: Corrosion Protection, Colorgalv

Galvanized Steel in Parking Structures

Posted by Howard Levine on Thu, Feb 21, 2013 @ 10:10 AM

 

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Steel is an exceptional building material. It has come into its own as a recognized, aesthetically pleasing part of the built environment. Since parking garages are no longer viewed simply as secondary structures in a project’s master plan, there is a need for a well designed architecturally impressive building. By working together, the entire building team can create work that is cost effective, long lasting, and beautiful.  

Unfortunately, most areas where fabricated steel products are used are subject to hostile atmospheric conditions or direct contact with aggressive chemicals. Deicing salts, vehicle emissions and acid rain are the most common culprits. For the steel to last and do its designed work, it must be protected from this corrosive attack.  

Hot Dip Galvanizing has been protecting steel from corrosion for centuries. Galvanizers understand the problems and have developed creative solutions. The problems of the parking industry are severe, but solutions achieved in other industries have enabled galvanizers to meet the challenge.  

Some of the advantages of hot dip galvanizing in parking structures are:

  • The life expectancy of hot dip galvanized coatings is a proven, measurable factor. As zinc protects steel by sacrificing itself, the life of the coating can be accurately predicted by dividing the existing coating thickness by the average coating loss per year. The longevity calculations are based on empirical data, not theoretical. The result is the life to first rust (not failure). In most cases, the calculated life of most areas exceeds 40 years.

  • Hot dip galvanizing has been extensively used in the industry. Sign supports, landscape components, highway architecture, noise barriers and many other items are currently specified to be galvanized.

  • When galvanized, the galvanizer has sole responsibility for the coating system. As no recoat will be required, the problem of "mixed systems" for maintenance doesn't occur. Maintenance of records for prior coatings is simple ---it was galvanized.

  • The coating adherence and quality are simple to inspect and verify. If the base steel isn't properly cleaned and prepared, it will not coat. Hot dip galvanizing is the only corrosion protection system that guarantees that the steel is perfectly clean before application of the coating. There cannot be a metallurgical bond between the steel and zinc unless the steel is 100% contaminant free.

  • Hot dip galvanizing is the only system available that protects the steel on the inside as well as the outside. This is especially important in the case of tubular materials which cannot be maintained on the interior. Left untreated, the corrosion can rapidly spread from the interior of the tube to the outside ultimately resulting in a structural failure of the component. By coming in contact with moisture, the untreated steel will "bleed" onto the ground, concrete or other appurtenance. Occurring long before a loss of structural integrity, however, will be an aesthetic failure.

  • Galvanizing is a factory process and is not dependent on weather or other external conditions. This allows fabricators and contractors the ability to accurately schedule site deliveries, erection times and eliminate delays.

There is an inherent difference between hot dip galvanizing and other protective coating systems.  Basically, steel is protected from corrosion through either barrier or cathodic methods. Barrier protection occurs when the protective mechanism acts to prevent the steel from coming into contact with the contaminant. How well it does its job is totally dependent upon the three “legs” of the coating triangle: Surface Preparation, Application, and Material. If the steel has not been prepared properly or if the application is done in less than ideal conditions, the coating will fail and corrosion will result. Paint is one example of the barrier method.  

Cathodic protection is a process whereby the metal is protected from corrosion by changing an element of the corrosion circuit. A form of cathodic protection is called the sacrificial anode method. In this system, a metal that is anodic to the metal to be protected is introduced into the corrosion circuit and becomes the anode. The protected metal then becomes the cathode and will not corrode. Zinc is anodic to iron and steel and by forming a metallurgical bond between the coating and the underlying steel, hot dip galvanizing provides cathodic protection as well as barrier protection.  

Furthermore, since the hot dip galvanizing process calls for the steel to be immersed into a bath of molten zinc and other earthly metals, it is being protected on 100% of its surface. This protection is critical and unavailable in other types of corrosion protection. It really serves no useful purpose to have a wonderful design, fabricated perfectly, with "rust bleed" staining the steel or adjacent material. This discoloration will lead to the public’s perception of inferior workmanship and lack of maintenance. As much attention must be paid to this particular issue as to the proper fabrication techniques. Since many garage components are tubular, it is important to specify a corrosion protection system that will not only protect the steel on the outside, but on the inside as well.   In addition to providing corrosion protection, galvanizing’s pleasing gray color meets many visual requirements as well. Typically, galvanized steel will oxidize to a uniform patina. However, when the need for color is required for safety reasons or the design calls for a particular color scheme, galvanized steel can be successfully topcoated.

Contact Duncan Galvanizing

By following a proven formula, Duncan can add the beauty and additional longevity of a high performance coating system over galvanizing. For more information on the available paint and powder coating systems, and their warranties, please contact us at 617-389-8440 or fill out a contact form.

 

Tags: Corrosion Protection, Hot Dip Galvanizing, Duncan Galvanizing

What is the Production Process for Hot-Dip Galvanizing?

Posted by Popi Papadonta on Wed, Dec 21, 2011 @ 01:15 PM

Step 1: Surface preparation

Thorough cleaning is necessary as zinc will only adhere to clean steel. This gets accomplished by:

  • Degreasing: a hot alkaline cleaner is used to remove oil, grease, dirt, loose particles, and any other contaminates that may exist on the surface of the material

  • Acid pickling: an acid bath is used to remove mill scale and oxides

  • Fluxing (dry kettle): pre-fluxing in a zinc ammonium chloride solution to remove oxides and to prevent oxidation prior to dipping into molten zinc

Step 2: Immersion in bath of molten zinc

During this step, the steel is immersed in a bath of molten zinc at approximately 830˚F. The mix in the bath consists of ~98% pure zinc and 2% additives (Al, Bi, Ni). The zinc reacts with the iron in steel and it forms a coating which is metallurgically bonded to the steel. Also, the zinc flows into recesses and other areas difficult to access, coating all areas of complex shapes thoroughly for corrosion protection. Hot dip galvanizing is the only coating system that protects tubular steel on the inside. The zinc goes “in, around, over, under and through” the fabrication. 

hot dip galvanizingThe size of zinc baths varies from galvanizer to galvanizer and this restricts the size of steel that can be galvanized. When choosing a galvanizer, make sure that the size of the zinc bath is big enough to accommodate the size of your products such as large structural shapes. 

The final product is protected against corrosion as zinc creates a barrier between steel and the environment and also cathodically protects the base metal. 

Step 3: Finishing


After the steel is withdrawn from the galvanizing bath, excess zinc is removed by draining, by vibrating or for small items, by centrifuging. The galvanized item is then cooled in air.


Step 4: Inspection

Steel is inspected after galvanizing to verify conformance with specs

 

Contact Duncan Galvanizing

For high-quality hot dip galvanizing, color galvanizing, and more, contact Duncan Galvanizing at (617) 389-8440 or fill out a contact form.

 

Sources: Duncan Galvanizing Corp., American Galvanizers Association

Tags: Corrosion Protection, Hot Dip Galvanizing, Duncan Galvanizing