Corrosion resistancy e+ loggers
The e+ loggers of Eijkelkamp Agrisearch Equipment are made from 316L stainless steel.
316L stainless steel is a commonly used stainless steel for outdoor applications and is used by a great many manufacturers
in their products.
Stainless steel is often commonly called rust-resistant steel. This unjustly implies that it cannot rust.
An oxide layer forms on the surfaces of most metals when they are exposed to air (oxygen) and water. The oxide layer that
forms on ordinary carbon steel is called rust and it scarcely protects the steel against further rusting.
However, the chrome that is added to stainless steel means that a thin and, in particular, dense layer of chromium oxide forms
on the surface of the steel. This layer gives stainless steel its good corrosive resistance and prevents the steel from further
reacting with the atmosphere. This layer is also called the passive layer.
The thickness of this passive layer depends on the composition of the stainless steel, the surface treatment and the environment in which the steel is located. The passive layer “recovers’’ when damaged by reacting with oxygen in the air, meaning
repair is not necessary. Because this recovery occurs in ambient air, the quality of this air affects the final result. Corrosion
occurs when the passive layer is damaged and it cannot recover because too little oxygen is present.
1.
Corrosion after mechanical damage
If the passive layer is damaged mechanically and then immediately sealed against the effects of the air, the passive layer cannot recover. Consequently, the stainless steel is prone to corrosion in this area.
As indicated above, the quality of the ambient air affects the quality of the recovery of the passive layer. In ambient air with
a relatively large amount of chlorine ions (e.g. sea air) recovery will proceed more slowly or may partially stop.

So try not to damage the loggers!
NB: As an indication: recovery takes a few minutes under normal conditions.
2.
Pit corrosion
This corrosion is very local and arises because the passive layer is broken in weak places by chloride ions or other halogens
or sulphates.
Such a spot takes on the properties of an anode and the other surface acts as a cathode.
Because the anode surface is small and the cathode surface is large, the current density at the anode is large and the speed
of corrosion is therefore high.
The local concentrated chloride ions form a film and therefore seal it against exposure to oxygen, thereby making recovery
more difficult (or stopping it).
Coastal areas and industrial environments are the most aggressive environments owing to high concentrations of halogens
or sulphates.
The sensitivity for pit corrosion increases as the concentration of chloride (e.g. sea water) increases, as the temperature increases and as the acidity increases (lower pH).

Not much can be done against this form of corrosion.
However, regularly cleaning the loggers helps.
All it takes for environmental research
© June 2008
P.O. Box 4, 6987 ZG Giesbeek,
the Netherlands
T +31 313 88 02 00
F +31 313 88 02 99
[email protected]
I www.eijkelkamp.com
AP.P4.32.02.E
3.
Biological corrosion
Biological corrosion is material damage caused by micro-organisms. Micro-organisms are present in all naturally humid environments. They attach themselves to almost all surfaces, multiply and produce biomass.
Biological corrosion is no new form of corrosion, but accelerates the other corrosion mechanisms.
Biological corrosion protects the oxidation area against oxygen and any recovery of the passive layer is made more difficult
or stopped.

This form of “corrosion” can be prevented/stopped by regularly cleaning the loggers.
4.
Contamination corrosion
This is not corrosion of the stainless steel but oxidation of (usually) steel particles that land on the stainless steel.
These steel particles can come from anywhere, e.g. a customer’s workplace, a car boot or iron from surface water.
This form of oxidation is initially reasonably harmless to the logger, it only looks odd.
However, this may promote other forms of oxidation if this form of oxidation remains on the logger for longer periods.

Regular cleaning is also recommended for this form of corrosion.
In the table below, the suitability of some stainless steel types under atmospheric conditions is indicated.
Type
Rural
Urban
L MH
L
M H
L
304, 321, 304L
2
2
2
3
3
316, 316L, 316Ti
1
2
2
2 2
1
1
1 2
Industrial
M Maritime
H
L
M
H
3 4
2
3 4
2 3
2 2 3
L = Low: low risk of corrosion in this environment owing to low temperature and humidity
M= Medium: normal corrosion risk in this environment
H= High: high risk of corrosion in this environment
1 =
2 =
3 =
4 =
5.
Probably more resistant than necessary for corrosion control
Probably the best choice as far as corrosion control is concerned
Can be considered if precautionary measures (cleaning afterwards or coating beforehand) are taken
Serious corrosion will occur
Maintaining stainless steel
Dependent on the degree of contamination, stainless steel must be cleaned step by step, preferably using corrosive agents as
sparingly as possible. If necessary, repeat the activities several times before turning to another method. Regular cleaning usually prevents serious deposits of dirt building up and ensures that any dirt that is deposited can be removed relatively easily.
5.1
Maintenance interval / inspection interval:

It is recommended that stainless steel be inspected at least once a year and be subject to one standard cleaning
procedure once a year.
The circumstances on site can influence the inspection interval. In order to gain a good impression of the situation, it makes
sense to carry out the first inspection after 6 months. Dependent on the degree of corrosion or how the steel has been affected, after cleaning, the interval can be reduced to 3 months if required.
5.2
Standard cleaning
Regular maintenance can best be performed using a pH-neutral cleaning agent that does not contain chlorides. A 5% solution
with warm water should be sufficient to remove any dirt. Normally any cleaning agent (a weak soap solution) that can be used
for glass (e.g. detergent dissolved in warm water) suffices. A small amount of ammonia, dissolved in warm water, can be used.
In case of more severe dirt / corrosion, use can be made of a mild, preferably non-abrasive, powder, such as washing powder.
This can be used with warm water; use a soft brush, a nylon sponge or a soft cloth. Avoid using wire brushes, steel wool,
chlorides, acids, etc. Where possible, avoid making additional scratches / damage, which cause(s) dirt to bind more rapidly to
the stainless steel and increases the chance of corrosion.
5.3
Formation of rust and/or pitting and crevice corrosion

If this is observed, preferably first contact Eijkelkamp!
A more aggressive cleaning method must be used for more serious corrosion. A small amount of vinegar can be added to the
cleaning powder, or sodium carbonate can be used. Here you can use, for instance, a pan scourer.
In extreme cases a mild, fine abrasive can be used without additives such as chloride and/or environmentally harmful substances.
Employ slight pressure and preferably follow the direction of any manufacturing marks.
Rinse with clean water. Allow the stainless steel to dry in the open air for approximately 15 minutes, to allow the oxide layer
(which is a self-forming protective layer) to reform.
6.Conclusion
The 316L stainless steel used by Eijkelkamp Agrisearch Equipment will be more than adequate under normal circumstances.
Regular cleaning will increase its lifespan with respect to oxidation.
Under extreme conditions, one must account for a risk of oxidation on the logger.
Extreme conditions are a relatively vague concept but one should think of:
• Close to sea
• Very contaminated soil (of course, the type of contamination also plays a role)
• Very contaminated ground and surface water (of course, the type of contamination also plays a role)
Documents with more details on chemical resistance are available upon request.