Home' Ships and Shipping : July 2009 Contents One of the main problems with stainless steel is that it is
susceptible to rust if it is denied correct maintenance. In this
article, some common rust problems are dealt with, showing
how rust can be removed by using a new organic product.
One of the causes of flash rust is when small steel particles swirl
down onto a stainless steel surface. When combined with
moisture, they quickly dissolve due to the low electrical potential
of the steel particles. During dissolution of the steel particles, iron
oxides are created that contaminate the surface of the stainless
steel. Examples include steel particles that are the result of wear
and tear, such as occurs near railway tracks, as well as grinding
dust and showers of sparks that develop during carbon steel
grinding. This is why stainless steel needs to be protected from
carbon steel and must be processed separately from carbon steel.
Local rust spots can also develop due to aerosols. This primarily
occurs in marine environments. Aerosols are small droplets of
seawater that are carried from the sea by the wind and which
evaporate during their flight leading to a further increase in salt
and chloride concentrations. This forms a greater corrosive load for
stainless steel than normal seawater. The result is local corrosion
that can also even lead to pitting corrosion. In general it can
therefore be said that stainless steel is not maintenance free.
Thanks to an extremely thin and dense oxide film, stainless steel
continues to display rust-resistant behaviour because this film
remains intact thanks to the oxygen present in the air. If this layer is
perforated by steel particles, then this film will be unable to recover
automatically. Under the oxide film there is always an active metal
and as soon as moisture is added this will start corroding.
Normally, damage to the stainless steel surface will not produce
any problems because the oxygen in the atmosphere will repair the
film in that area again; this is why this effect on stainless steel is
also known as ‘self healing’. This unique property disappears,
however, as soon as the surface becomes contaminated and the
rust formation that is initiated will therefore spread until the
material is bored through.
Local rust formation can be removed with pickling liquids or
pickling pastes as well as with inorganic chemicals. In some cases
this can also be done mechanically with, for example, sandpaper,
special scourers or stainless steel brushes. The disadvantages are
generally well known, as scouring damages the surface
considerably and, in addition, the scoured area is often less
Pickling is harmful to the environment and dangerous for the
people working with it. Regular inhalation of the hydrogen
fluoride present can even lead to a pulmonary embolism. The use
of inorganic acids also has its dangers and is also subject to
stringent rules and guidelines.
This is why an oxide-dissolving organic agent called Innosoft
B570 is now available that gives a very effective and efficient result.
In figure 1 you can see light fittings made from stainless steel 316
that were only in use in a maritime environment for one and a
half years. The top sections still show the severity of this
contamination by aerosols. After use of the organic acid Innosoft
B570, the surface was quickly restored to its original condition. The
bottom fitting has partially been treated with this.
One must not lose sight of the fact, though, that small scars
may have developed in the surface that could quickly lead to new
corrosion as soon as the fittings are put back in place. This is why a
basic neutralizer has been developed that also deposits a nano-
layer on the surface to provide protection against possible new
corrosion. This product will be introduced on the market under the
name Innoclean B560.
A maintenance protocol will also be needed in this case as all
things come to an end. In other words, the surface will need to be
cleaned and the nano-layer reapplied periodically. Various
maintenance advice can be found on the Internet regarding stainless
steel. Unfortunately, reputable companies sometimes issue advice
that is often at odds with what should actually be done.
For example, advice is given to clean contaminated stainless
steel with steel wool or a scouring sponge. This should particularly
be avoided as steel wool is something that contaminates stainless
steel and a scouring sponge damages the surface. This is why
Innosoft B570 is a product that only dissolves the iron oxides. In
other words, it is gentle on stainless steel but tough on oxides and
all kinds of dirt.
A good example can be seen in Figures 2 and 3. A stainless steel
flange 304 was kept in a plastic bag in which ferruginous water was
present. The flange came out of the packaging in such a state that
it was ready for the scrap heap. This problem was easy to solve
with the afore-mentioned organic cleaner and the flange was
reconditioned in no time at all. These imperfections do require
extra care as they can quickly set the corrosion mechanism in
motion again. In that case, the invisible nano-layer also provides
some additional protection.
Moreover Innosoft B570 also has a deep cleansing effect as well
and this is of significant importance as dirt can settle as a deposit,
particularly on a somewhat rougher or ground surface. This can
lead to “under deposit attack” which is a form of corrosion that
only occurs under these types of depositions.
For further information contact:
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