Roxul Industrial Insulation Process - Manual (Page 24)

Planning and pr
epar
ation
1.1 Planning and preparation
The table further on this page, which has been
derived from the standard DIN 4140, indicates the
initial risks of electrochemical corrosion in cases
where various combinations of metals are used. Note
The table does not take into account forms
of corrosion with other root causes, such as
stress corrosion. For further information, see
Chapter 2.2 “Product properties & test
methods” – AS-Quality on page 115.
Material Combination material
Metal
Surface ratio in proportion to
combination material
Zinc Aluminum
Ferritic
steel
Lead
Austenitic
stainless
steel
Copper
Zinc
Small - M M H H H
Large - L L L L L
Aluminum
Small L - L H H H
Large L - L M L H
Ferritic steel
Small L L - H H L
Large L L - L L L
Lead
Small L L L - H H
Large L L L - M M
Austenitic stainless
steel
Small L L L L - M
Large L L L L - L
Copper
Small L L L L L -
Large L L L L L -
L - Light or little corrosion to material
M - Moderate corrosion to material, for example, in very humid atmospheres
H - Heavy electrochemical corrosion to material
Observation: The table shows the corrosion of the “material”, and not that of the “combination material”.
“Light” means: “small-scale in proportion to the combination material”, “heavy” means: “large-scale in
proportion to the combination material”.
Example 1: Material is a zinc galvanized screw in combination material, a cladding made from austenitic
stainless steel: Row “zinc small”: “H” – heavy corrosion of the screw.
Example 2: Material , a cladding made from austenitic stainless steel screwed on with a screw galvanized
with combination material zinc: Row “austenitic stainless steel large”. “L” – the corrosive attack upon the
austenitic steel is light.
Electrochemical Corrosion Potential
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