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Recommended finishes for different
environments
In planning any cabling or
support installation the choice
of an appropriate corrosion
resistant finish is always a key
issue at the specification stage.
The correct choice of finish has
long term implications and is
crucial for ensuring the longevity
(and aesthetics) of the complete
installation in order to meet with
the client’s expectations.
It is vital that the finish specified
for the equipment is capable of
providing lifetime protection from
corrosion within the intended
environment - ideally with some
margin of safety.
The following pages give
information on how corrosion
occurs. Contact our technical
team on +44 (0) 845 605 5334 for
further information.
Corrosion occurs on all metals
to some extent. With some, such
as stainless steel, its effects
are usually only slight but even then the presence of certain
chemicals or physical contact with other metals may cause rapid
corrosion. It is therefore important to consider every aspect of
the environment surrounding any intended installation in order
to choose a material or finish which will minimise the risk of
damage to the support system through the effects of corrosion.
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Chemical (atmospheric) corrosion
Few metals will suffer corrosion damage in a dry, unpolluted
atmosphere at a normal ambient temperature. Unfortunately
atmospheric pollutants are likely to be present to some degree in
most situations where support systems will be installed, thus mild
chemical corrosion is normal in almost all situations.
Any support installation which will be situated in an area where
higher concentrations of chemicals exist must receive more
detailed consideration in order to select a finish which provides
the best combination of initial cost and expected life. More
detailed information is available upon request, please contact us
on +44 (0) 845 605 5334.
2
Electrochemical (galvanic) corrosion
When two dissimilar metals are in contact and become damp it
is possible for corrosion to be induced in one of the metals. Such
corrosion may progress rapidly and cause considerable damage
so it is important to consider and, if necessary, take steps to
eliminate this process occurring.
Electrochemical corrosion takes place because the two different
metals each behave as electrodes and the moisture as the
electrolyte in a simple battery; as with any battery the resulting
flow of current will cause corrosion of the anode.
The likely effects of this reaction can be predicted using the
Galvanic Series.
Suitability of finishes
IN THIS SECTION...
Suitability of finishes
1. Recommended finishes for
different environments
Preventing corrosion
1. Chemical (atmospheric)
corrosion
2. Electrochemical (galvanic)
corrosion
3. The merits of Zinc
4. Common corrosion
situations
Selecting the
right finish
Preventing corrosion
❍
Recommended
◆
Possible
Internal installation,
normal environment
❍
❍
External installation,
urban environment
◆
◆
◆
❍
❍
Temporary external installation
during construction phase
◆
◆
❍
Chemical industries,
nitrate explosives,
photography, decoration
◆
◆
❍
Marine, harsh, sulphurous
(weak concentration)
environments
◆
◆
❍
Acid or alkaline environments
◆
◆
◆
❍
◆
Food production environment
❍
❍
Halogen environment
◆
❍
EZ
GS
GC
DC 304L
316L
EZ+
Typical atmospheric environments in relation to suitability of finishes
Differences in potential are expressed in millivolts.
Beneath the red line, the metal involved is attacked.
Stainless steel
Stainless steel
0
Nickel
180
Copper
320 140
0
Brass
400 220
80
0
Tin
550 370 230 150 0
Steel
750 570 430 350 200
0
Aluminium
840 660 520 440 290 90
0
Chromium
950 770 630 550 400 200 110
0
Zinc
1150 970 830 750 600 400 310 200
0
Steel
Aluminium
Nickel
Copper
Brass
Partner metal
Metal involved
Chromium
Zinc
Tin