Twice the Corrosion Resistance
 In
order to provide the finest grain storage products possible
Twister began using Galfan steel in all flat bottom and hopper
bottom bins in 2002. While the appearance of Galfan steel is
quite similar to that of conventional galvanized steel, Galfan
steel offers a clear improvement over regular galvanizing in
a number of areas but particularly that of corrosion resistance.
What is Galfan Steel?
Galfan is a Zinc 5% Aluminum alloy with a mischmetal addition
that, when applied as a coating on steel, offers an improvement
over the performance of regular or lead-free galvanized steel.
Galfan is a patented alloy and registered trademark, both of
which are owned by International Lead Zinc Research Organization.
Galvanizing protects the underlying steel in two ways. First,
the coating material acts as a passive barrier and prevents
corrosive elements from reaching the steel. The second and
more important method of protection is the cathodic or sacrificial
characteristic of the zinc in the galvanizing. Even when scratching
or cutting exposes the underlying steel, the surrounding zinc
will corrode first rather than the exposed steel. Aluminum
corrodes more slowly than zinc so it provides a better passive
barrier but it does not have the superior cathodic qualities
of zinc. This product combines the strengths of both zinc
and aluminum and results in a far more corrosion resistant
coating.
Galfan Steel Performance
The useful life of the corrosion protection on steel depends
on the total thickness loss over time - less loss means longer
the life for the product.
Long-term testing of Galfan steel by Center de Recherches
Metallurgiques, New Zealand Steel, Nisshin Steel and N.V.
Bekaert all show that the corrosion resistance of Galfan steel
is about twice that of regular galvanizing. The following
chart shows actual data taken from a Nisshin Steel Corp. study.
Galfan Steel Comparison
How about heavier coating on steel?
In comparing the corrosion resistance of different materials
it is fair to note that a thicker coating of zinc will result
in a longer life span. There are several coating thickness'
available but G90 (.8 mil per side) is the standard galvanized
steel used within the grain bin industry in North America. Improved
performance can be obtained through the use of a G115 (1.0 mil
per side) coating but neither of these coatings provides the
same protection. The expected years until red rust shows in
a rural environment for G90, G115 and Galfan with a .8 mil coating
are shown in the graph to the right.
Grain Bins that Last Longer
What all this means is that you can expect our grain bins
to last up to twice as long as those made from regular galvanized
steel. If you only require bins that last half as long, that's
OK - you can still get them from the competition.
|
Total Coating Thickness Loss, microns
|
|
Years Exposure
|
|
Exposure Type
Atmosphere
|
5*
|
7*
|
15**
|
|
Regular
Galvanize
|
Galfan
|
Regular
Galvanize
|
Galfan
|
Regular
Galvanize
|
Galfan
|
Ratio
|
RURAL
|
7.6
|
4.8
|
10.0
|
5.4
|
18.8
|
7.8
|
2.4
|
| INDUSTRIAL |
12.7
|
7.8
|
16.6
|
8.0
|
31.6
|
11.7
|
2.7
|
| MARINE |
15.5
|
8.8
|
20.7
|
10.5
|
39.9
|
16.0
|
2.5
|
| *Actual Nissin Data
** Extrapolated Data |
|
Galfan
Steel