A long lasting corrosion protection is neither achievable with a hot-dip galvanizing nor with a hot-dip
galvanizing and an additional powder layer ( "Duplex" -procedure) as is demonstrated in the traffic
engineering. In case of breach of the surface an effective repair is equally not possible. The
outgassing of the zinc coating can create through pore formation in the powder coating an access gate
for humidity infiltration. Corrosion protection warranties are provided - if at all - only in the
framework of the statutory minimum requirement.
High demands for the corrosion protection can be realized with wet painting processes - accordingly
warranties are extended. Corrections of surface imperfections are possible. In addition, the
multi-layered system, which is applied manually at the construction site, is very time-consuming and
expensive (the cost for the Paris Eiffel Tower is for example 10 % per year of the respective steel
cost).
A pure CDP-coating already offers a permanent anti-corrosion protection, which exceeds that of the
previously referred systems. It is not UV resistant, however this can be achieved by an additional
powder coating. Above average warranties of up to 10 years and longer are granted.
The OR 6000®-System has the highest corrosion
resistance, including naturally a UV-resistance. Through the automated manufacturing process a
consistent corrosion protection result the highest level is achieved. The company BOT Surface
Technology of Kulmbach, Germany guarantees of up to 50 years on their system! Imperfections can be
successfully repaired selectively and and a reasonable expense at a later time - an "Infiltration" of
the first protective layer by moisture does not exist. Ultimately the cost of the surface protection
amounts to only approx. 50% of the wet coat process and maintenance is relatively unnecessary.
Hot-dip galvanizing wears off in time it "corrodes" permanently. The corrosion process is
recognizable by the white dust (so-called white rust), which forms on the surface. For this reason the
the galvanization industry is hard pressed for warranties. Mainly because important operations of the
hot-dip galvanizing process can only be executed manually - which will inevitably lead to porous
surfaces and inclusions, and thus massive loss of quality in case of improper execution. Entirely
worthless are the warranties of the hot-dip galvanizing industry against "red rust", because it is
impossible to occur. And against the so-called "white rust" there is no guarantee, it will undoubtedly
occur - the zinc depletion is particularly strong in chloride or sulfate enriched environment (as is
the case, for example, in salty air or hydrochloric acid).
Very strong and rapidly depleting the protective zinc coating also, are two galvanized steels where
the surfaces are directly touching. This so-called galvanic corrosion can only be avoided by a
particularly expensive handling. Even when using other materials such as stainless steel
screws/anchors a galvanic corrosion occurs. To the contact points of the zinc and stainless steel a
strong rust formation occurs
Therefore, the hot-dip galvanizing industry offers a "Duplex" procedure, which is also recommended in
some applications (e.g. motorway construction) by the German Federal Environment Agency. In this the
galvanized steel is powder or liquid painted with an additional layer. Even with the
"Duplex"-Procedure the galvanizing industry finds it difficult to issue a warranty and - if at all -
only a warranty of 5 years is granted. Why is that? The "Duplex"-Procedure is technically almost
impossible to achieve, because of the white rust forms very quickly and the white dust prevents an
adhesion of the powder coating with the substrate. The result: After just a few years the powder
coating flakes of over large areas. Should this not be the case, a number of additional labor and
energy-intensive steps in the processing of the zinc coating as a primer coat are necessary - however
the cost becomes prohibitive. In practice the Federal Highway Research Institute already criticizes
the the formation of rust in "Duplex" systems.
The newly developed steels, in particular the high-tensile steels, are due to the oxide formation of
the alloys almost completely unsuitable for hot-dip galvanizing.
A good corrosion protection can be achieved with multi-layered wet painting systems. The total layer
thickness, in accordance with the Norsok Directive M-501, can measure more than 1,000 my ( ! ). In
corrosion tests of 4,200 hours and more, eventually every wet coat system will show some form of
fatigue. In addition, such layers are very labor-intensive and costly, as the coating with liquid
paints is usually applied at the location, which in itself is already more expensive (assembly hourly
rates, trigger-, control- and efficiency problems). In addition, there is the dependence on the
weather conditions, which can lead to downtime. And in order to achieve a stable coating system,
highly qualified, conscientious staff is essential. The example of the Eiffel Tower demonstrates the
cost for the permanent maintenance of the surface protection each year about 60 ? per ton steel, i.e.
approx. 10 % of the purchase cost of the steel itself. In other words, after 10 years, the maintenance
costs just as much as the entire steel used for the construction.
In relation to the anti-corrosion protection OR 6000® by
far exceeds both the possibilities of hot-dip galvanizing and of the "Duplex" system as well as the
possibilities of the thick layered wet coat painting. This is proven by the extensive tests at the
independent Institute for Paints and Coatings (ILF) in Magdeburg. Because of the industrial,
consistently fully automated machining processes of
OR 6000® the individual coatings are perfectly matched to
each other and are extremely even in the layer thickness - the total layer thickness is only 120 - 230
my. Therefore the highest possible quality results can be repeated as often as desired. The company
BOT Surface Technology, Kulmbach, Germany grants warranties of up to 50 years! on the system! /p>
Distinct differences between the individual procedures become apparent once the surface has been
damaged and the steel is exposed at one point. In case of the
OR 6000® -system only this one location is affected by
rust. The damage can be repaired in a subsequent ad hoc repair quickly and inexpensively. In case of
hot-dip galvanizing, the "Duplex" process and the wet paint coating the moisture"creeps", between
steel and the first protection layer and is not usually visible. A repair of the imperfection is
possible but worthless, because the corrosion process has affected a large area underneath the first
protective layer. Permanent rust will be the result. This infiltration of the first protective layer,
does not exist in the case of
OR 6000®.
In addition, higher environmental temperatures may negatively effect "Duplex" systems, as zinc
creates heat gases, which collect under the powder coating, which lead to unsightly bubbles or, at
worst case, lead to pores by which moisture can enter from the outside.
OR 6000®
does not gas out and has a temperature resistance up to 150°C.
