BENEFITS OF HOT DIPPED GALVANIZING
Lowest First Cost- Hot Dip Galvanizing is lower in first cost than many other commonly specified protective coatings for steel. This is true because of the manufacture rebates, and no painting costs.
Lowest Annual Cost- Fleet managers will notice that Annual expense will decline, since Hot Dip Galvanizing is very durable, the need to sandblast and re-paint every three or four years is NOT necessary. Fleet managers will notice that manpower requirements, shop supplies, and capital equipment costs for sandblasters and painting equipment and booths will be less and in some cases non exisitence.
Lowest Long Term Cost- Even in cases where the initial cost of hot dip galvanizing is higher than alternative coatings, hot dip galvanizing is almost invariably more cost effective in the long term because it lasts longer and needs less maintenance.
Long Life- The life expectancy of hot dip galvanized coatings on typical structural members is far in excess of 30 years in most rural environments, and 15 to 20 years plus, even in severe urban and coastal exposure.
Exclusive feature of galvanizing- Hot Dipped Galvanizing has one key feature that out performs all other metal coating, hands down. Edge protection on sheet metal, I-beams, sharp corners, under bolt spacers and washers, bolt holes is outstanding. In fact, no other metal coating paint, E-coatings, powered coatings can compete with hot dipped galvanizing when it comes to protecting areas that are mechanically abused, through normal assembly, operation use, or abuse.
Reliability- Galvanizing thickness is carried out to the appropriate Industry standard for hot dip galvanizing. Coating life and performance are reliable and predictable.
Toughest Coating- A hot dip galvanized coating has a unique metallurgical structure which gives outstanding resistance to mechanical damage in transport, erection, and service. If the engineering specs require double duty, double thickness for longer life, the specs for double thickness of galvanizing on the product can be written, and a thicker coat of galvanizing can be applied. Double thickness for any type of paint coatings is a waste of money, and accomplishes absolutely nothing in attempts to increase the longivity of the equipment.
Automatic Protection For Damaged Areas- Hot Dip Galvanized coatings corrode preferentially to steel, providing cathodic or sacrificial protection to small areas of steel exposed through damage. Unlike organic coatings, small damaged areas need no touch up.
Complete Protection- Every part of a hot dip galvanized article is protected, even recesses, sharp corners and inaccessible areas. No coating applied to a structure or fabrication after completion can provide the same protection as hot dip galvanizing.
Ease of Inspection- Hot Dip Galvanized coatings are assessed readily by eye, and simple non-destructive thickness testing methods can be used. The hot dip galvanizing process is such that if coatings appear sound and continuous then they are sound and continuous.
Faster Erection Time- As hot dip galvanized steel members are received they are ready for use. No time is lost on-site in surface preparation, painting and inspection. When assembly of the structure is complete, it is immediately ready for use, or for the next construction stage.
Reliability Factors for Hot Dip Galvanizing versus Paint |
There are two types of coating failure; predictable and unpredictable. All coatings are designed to provide a certain level of performance in a specified environment. If failure occurs prematurely, something has gone wrong!
If failure occurs, it is generally the result of a problem associated with the selection or application of the coating. It is possible to evaluate the chances of a coating failing prematurely using statistical methods to determine the Reliability Factor of a particular coating system. This work was done initially by Dr. J.F.H. van Eijnsbergen in the Netherlands to develop simple statistical methods for evaluating the reliability of any applied coating.
Dr. van Eijnsbergen developed a scale of Relative Importance in which a factor (I) can be allocated to each and every element in the coating process. This factor is logarithmic and rates the importance of a particular element in relation to the coatings performance.
Factor
8
4
2
1
0.25
0.125Importance
Very high or dominating in comparison to all other parameters
High or dominating in comparison with all other parameters
Significant over other parameters
Equivalent value to other parameters
Of minor significance over other parameters
Of no significance in comparison to other parameters
By allocating Relative Importance Factors (IR) to the elements making up a coating system, a Total Reliability Factor (FT) can be obtained from the sum of these. The lower the FT, the higher the reliability of the coating system.
By applying Relative Importance (IR) factors to such elements as steel surface condition, weather conditions, presence of soluble salts, surface preparation and other elements to whatever level is deemed necessary for a particular analysis (there are more than 100 factors to which Relative Importance (IR) factors could be applied in relation to coatings), the particular coating system's reliability can be given some statistical significance.
To assist in logically rating performance, a Degree of Reliability (RT) factor can be produced using the formula RT = 100 / FT. The higher the Degree of Reliability (RT), the higher the level of coating reliability in relation to other coatings.
Reliability Parameters
There are six basic parameters that impact coating reliability. These are;
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1. Steel surface and shape |
4. Application of coating system |
Each of these parameters has its own set of parameters which is important in determining the reliability of a coating system.
Why is Hot Dip Galvanizing so Reliable?
Both Factory applied paint coatings and especially field applied paint coatings will always be less reliable than factory applied galvanizing. A simple test is to observe the performance of paint coatings vs galvanizing coatings in service today. In the entire USA area there are VERY few examples of galvanized coating failure on millions of items that are in service throughout the United States. Signposts, fence posts, guardrail, mesh fencing, trailers, transmission towers and countless other hot dip galvanized items are still doing there job preventing rust with the intact coatings after 20, 30 or 40 years.
When you look around at painted steel surfaces you also will find a major repainting industry, thriving and very profitable attempting to address the major and frequent paint failures in the public domain. However, In today's market it is nearly impossible to find a maintenance galvainzing industry as it is NOT needed.
The reason manufacture or field applied paint coatings are far less reliable than hot dip galvanized coatings can be shown statistically by applying the Reliability Factor analysis above to each system using the parameters that are relevant to the application of the coatings.
Conclusion
When the numbers are worked it illustrates that PAINTING IS Almost 400% more likely to fail in a typical paint application. Another way to say it is Galvanizing is 400% better than painting. On the other hand, once the hot dip galvanized coating is present it will NEVER FAIL due to application related factors as the galvanized coating will not form unless the steel surfaces is prepaired and fluxed before dipping. Hot dipped Galvanizing molecules have interelaced with the steel molecules at the surface and pentrated below the surface. Bottomline is galvanizing is molecule bonding or marriage of metals, at and below the surface. No painted application can compete with galvanizing for protection against the elements and mother nature. Paint looks good until you drive it off the dealers lot. Once the unit is put to work, the rust battle is lost.
In rugged appliations such as dump bodies, painted coat will reliabliity last as long as the first rugged use of the equipment. As soon as the paint coat is pentrated, or nicked rusting will pentrate under the paint coat. The laws of nature are time honored and the rusting process will destroy the best paint job quickly. Hot dipped galvanizing never fails due to poor applications and their performance is not subject to handling or transportation.
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