Sep. 30, 2024
The true cost of protecting steel work from corrosion has to take into consideration two important elements:
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What is the cost of galvanized steel?
Hot dip galvanizing is often perceived to be more expensive than it is. There are two reasons for this: Firstly, that such a high performance coating is automatically assumed to be expensive. Secondly, the initial cost of galvanising relative to paint has changed significantly over recent years. Painting costs have steadily increased whilst galvanising costs have remained stable.
Galvanizers Association commissioned independent consultants, The Steel Protection Consultancy Ltd (SPC), to investigate the galvanising prices and the cost competitiveness of galvanizing. SPC in conjunction with consulting engineers, WS Atkins, designed a typical, 240 tonne, steel-framed building and sent it out to tender.
The paint system was found to be 35% more expensive than hot dip galvanizing.
Two corrosion protection systems were specified; (i) hot dip galvanizing and (ii) a good quality, grit blast and three coat paint system of 250µm dry film thickness. Quotations from eight fabricators in different parts of the UK were obtained and averaged. The paint system was found to be 35% more expensive than hot dip galvanizing.
Figure 1 illustrates that for many applications the cost of hot dip galvanizing is lower than that of applying alternative coatings. The reason for this is simple: alternatives such as painting are very labour intensive compared with galvanizing, which is a highly mechanised, closely controlled, factory process.
The whole-life cost of a building can be defined as: &#;The cost of acquiring, operating and maintaining a building over its whole life through to disposal&#;.
Whole-life costing can be characterised as a system that quantifies financial values for buildings from inception and throughout the building&#;s life. It is an approach that balances capital with revenue costs to achieve an optimum solution over a building&#;s whole life.
This technique, whilst not in itself new, has over recent years become accepted best practice in construction procurement. Whole-life costing can be used at any stage of the procurement process and can be used at the levels of facility, function, system and component. This includes everything from initial design to end-of-life.
It is estimated that up to 80% of a building&#;s whole-life cost can be attributed to running, maintenance and refurbishment costs. Consequently, there are spikes in expenditure at 10 years and every five years after that.
The initial choice of materials and the way that they are protected obviously plays an important role within the maintenance and refurbishment costs of a building over its lifetime. They therefore have a very large influence on the whole-life cost profile of the project.
Smoothing the expenditure
Life cycle expenditure tends to inherently produce &#;spiky&#; profiles with large peaks at 10, 15, 20 and 25 years. Information supplied by Turner and Townsend, Construction and Management Consultants.
The overall cost of protecting a steel fabrication throughout its life depends on the cost and durability of the initial coating in the particular environment and, on the costs and frequency of any subsequent treatments where the required life exceeds that of the initial coating.
In the majority of applications, hot dip galvanizing will provide a long, maintenance-free life without any requirement for maintenance painting.
There are ways of calculating the benefits or disadvantages of different methods of corrosion protection. The most common method is to calculate the Net Present Value (NPV) of each method and compare the results. This calculation takes into account the cost of borrowing money, the initial cost of protection, subsequent maintenance costs and the lifetime of the project.
It is frequently used by companies to measure the likely outcome of a capital investment project.
Example
Take the case of a steel structure that has a projected life of 25 years and for which the discount cost of capital is 5%.
Galvanize: system 1
Hot dip galvanize to BS EN ISO with a minimum average coating of 85µm on steel of 6mm or more thick. As galvanizing to this standard has an average life expectancy of more than 50 years in the UK, it is very conservative to project a life of 25 years without further maintenance. Let the cost of galvanizing be a base figure of 100 units. There are no further maintenance costs. (NPV = 100)
Paint: system 2
A paint system consisting of cleaning followed by an undercoat and two top coats of paint. This system has a life expectancy of eight years and so will need be repainted three times in 25 years. The initial cost is slightly cheaper than hot dip galvanizing at 90 units. The cost of repainting for the first two occasions is 45 units but goes up to 90 units for the third repaint when the original paint must be removed. (NPV = 169)
Paint: system 3
A superior paint system consisting of blast cleaning followed by three coats of a higher quality paint. This system has a life expectancy of 11 years and will need to be repainted twice in 25 years. The initial cost is higher than the other paint system at 135 units. The cost of repainting is half this value at 67.5 units. (NPV = 197.5)
It can be seen that over a 25-year project life the cost of a &#;cheaper&#; paint system is almost 70% more than the cost of galvanizing.
A &#;cheaper&#; paint system is almost 70% more than the cost of galvanizing.
Likewise the cost of a more &#;expensive&#; paint system is almost double that of galvanized steel. In initial, or first, cost terms hot dip galvanizing is comparative with a good quality paint system. However, when looking at lifetime costs, hot dip galvanizing works out to be considerably cheaper than most other systems.
Money, Production, Environment, and Employee Health &#; Just To Name A Few
Our Customer Success folks tell me that customers frequently ask about the difference between EonCoat to galvanizing carbon steel. Primarily, companies tend to focus on the initial cost and the lifetime value. Those are great questions! Because EonCoat is a disruptive technology, engineers and fabricators who grew up with galvanized steel products may not immediately understand the differences.
An intelligent and thorough analysis will typically center on a few critical issues when comparing one coating system to another.
There are six main points to consider.
1- Corrosion performance
2- Initial cost
3- Long term cost
4- Damage to the environment
5- Health impacts to people on the job
6- Repair of damage to the coating
I&#;m going to break down each of these areas of focus.
CORROSION PERFORMANCE
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Galvanic protection is a rugged covering that lasts for a long time in areas not wet or salty. In other words, it works well if the environment isn&#;t corrosive.
The charts below, provided by the American Galvanizers Association, show the thickness of molten zinc applied to steel and the corresponding typical corrosion rates. The cost estimates in this comparison are based on the thicknesses in these charts. Therefore, more zinc would mean a higher initial cost.
The math shows that galvanizing, applied at the minimum recommended thickness, will only last an estimated 5 to 10 years in wet and salty areas but can last for a century in inland urban areas &#; in a dry environment with no salt in the air.
An applicator has good reasons to apply the minimum specified thickness in the galvanizing process. First, there is no practical method to repair or replace Galvanizing once the structures are in place. So if corrosion starts, there isn&#;t a cost-effective repair technique. It would be necessary to remove all galvanizing via grit blasting and start over with another method. Galvanized steel, and the industry attached to it, have become the beast that needs to be fed.
The applicator can increase the thickness and can therefore extend the life of the protected carbon steel asset. However, the end-user needs to be knowledgeable because the galvanizer&#;s cost increases significantly as the relative thickness increases.
EonCoat, as the alternative and disruptive technology, is a permanent corrosion prevention solution. Because of its unique formulation and application, we offer a 30-year warranty &#; even in harsh environments. We have outperformed all of our competitors in the most corrosive environments, including salty and wet areas.
INITIAL COST
According to the American Galvanizing Association, the initial cost of applying hot-dip Galvanizing, according to the American Galvanizing Association, ranges from $1.10 for light structural steel to $4.40 per square foot for heavy structural steel. In addition, the process galvanizing process must be done in a galvanizing-specific shop environment. That is a restrictive and costly barrier. The customer must now add travel costs to the galvanizing shop from the worksite. An asset owner must consider this additional expense when estimating the overall corrosion prevention and asset maintenance cost.
When a customer applies EonCoat in a shop environment and has accomplished surface prep with automated equipment, the estimated cost of EonCoat is around $2.00 per square foot regardless of the weight of the steel. Field application of EonCoat depends on the cost of surface prep and, more specifically, the cost of grit blasting media and local labor. Typical prices for field application can vary significantly with the geometry of the substrate and local conditions, including labor rates.
This information concludes that EonCoat is the lower initial cost solution for mid-to-heavy steel, and Galvanizing is initially less expensive for light steel.
LONG TERM COST
The life cycle cost of galvanizing is low for dry, inland areas because it can last for the life of the asset with no need to re-coat. Essentially the initial cost is the life cycle cost for dry, inland areas. The initial cost of EonCoat is also the life cycle cost. For EonCoat, this is true for even highly corrosive areas &#; specifically wet and salty environments. This ability to perform well in such diverse environments allows us to offer a 30-year warranty!
The long-term cost for galvanizing is exceptionally high for wet, salty areas. Either the initial application of molten zinc must be increased significantly to accommodate 8 microns-per-year of corrosion; or the galvanizing will have to be repaired at a relatively short interval. The cost of replacing galvanizing on an existing structure is prohibitive. In addition, it would be necessary to disassemble the structure and take it back to the galvanizer. This limitation leaves two uncomfortable options. Either let the structure rust or completely remove the zinc and re-coat with a conventional system.
Removal of the galvanizing is a costly proposition. Partly because it is not easy to blast off the zinc, but also because of the environmental hazards associated with removing galvanizing and the expensive precautions necessary to protect the workers who must do it.
EonCoat is clearly a much less expensive alternative to galvanizing for long-term exposure in wet or salty environments.
DAMAGE TO THE ENVIRONMENT
The US EPA lists zinc as a priority pollutant. Zinc impacts the environment by several routes. First, water is polluted with zinc due to the presence of large quantities of zinc in the wastewater of industrial plants and leaching from large, galvanized structures. The zinc gets into the water supply at levels that are toxic to fish because fish can accumulate zinc in their bodies when they live in zinc-contaminated waterways. When zinc enters the bodies of these fish, it can bio-magnify up the food chain. The zinc in our waterways, and therefore fish supply, can potentially become toxic to humans! Additionally, rivers are depositing zinc-polluted sludge on their banks because of the zinc runoff. Finally, water-soluble zinc that is in soils can contaminate groundwater.
You can also find large quantities of zinc in soils. When the soils of farmland are polluted with zinc, animals will absorb concentrations that damage their health. Zinc cannot only be a threat to cattle but also to plant species. Plants often have a zinc uptake that their systems cannot handle due to the accumulation of zinc in soils. On zinc-rich grounds, only a limited number of plants have a chance of survival. That is why there is not much plant diversity near zinc-disposing facilities. Zinc effects upon plants are a serious threat to the production of farmlands and, therefore, our food chain.
Review this data about the environmental impact of galvanized steel from the folks at Arcelor Mittal- Environmental impact of galvanized steel vs. bare steel per metric ton.
EonCoat, having a low carbon footprint and no toxins, does not cause any of these environmental issues.
HEALTH IMPACTS ON THE WORKFORCE
Zinc is toxic at high exposure levels. As an occupational inhalation injury, zinc can cause metal fume fever. Read more directly from the source:
&#; the inhalation of zinc oxide can lead to an entity known as &#;metal fume fever,&#; which usually occurs secondary to occupational exposure. In these cases, workers who suffer exposure to fumes through welding, alloy production, and soldering of metal can present with flu-like symptoms in addition to cough and dyspnea, presumably due to zinc&#;s direct effects on the pulmonary epithelium
The process of welding galvanized steel is commonly found in the metal fabricating industry. Many welders usually weld galvanized steel at some point in their career, and in doing so, they may experience galvanize poisoning or metal fume fever. Galvanize poisoning is a condition that results from overexposure to zinc oxide. Symptoms typically begin shortly after exposure to zinc oxide and may include a headache and nausea. A moderate case of exposure will result in symptoms including chills, shaking, a slight fever, vomiting, and cold sweats.
EonCoat contains no toxins, no VOCs, and no HAPs. We engineered all of our products to be water-soluble and inorganic. As a result, EonCoat is nonflammable and has no flashpoint. As a result, it is the safest corrosion coating solution for the workforce and the environment.
Additionally, EonCoat has developed a weldable product with the same safety standards. You can weld over the EonCoat Weldable with no loss of corrosion protection and no risk to the employee. Welding over zinc can create a list of issues &#; not to mention that some hot-dipped galvanization might contain trace amounts of lead or chromium.
REPAIR TO THE COATING IN CASE OF DAMAGE
Repair of EonCoat is a simple matter. Generally, no surface prep is required &#; spray more EonCoat on the substrate if any impact has damaged the ceramic. The same is true if an application error occurs and a local spot on the coating and a customer needs to perform a touch-up.
These types of repairs are not possible with galvanizing. Galvanizing must be done in a controlled environment in a specialized facility. No onsite repair is possible. If galvanizing fails or is damaged, the repair procedure must be some other type of coating solution.
ANALYSIS AND CONCLUSION
Considering the extensive protection in severe corrosion environments, easy repair, and the zero environmental and safety impacts of EonCoat appears to be the correct choice for most industrial applications.
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