Elcometer SCM400 - Page 14

12
English
If surfaces are heavily pitted (i.e. >1000 µm) it is possible that soluble salts will
be retained within the pits. If so, following the qualitative Potassium
Ferricyanide test (BS 5493- Appendix G) would aid interpretation on carbon
steel and low alloy steel surfaces. This test will only work on ferritic steel
surfaces.
Figure 5. Readings obtained at Various Temperatures
with Sodium Chloride
0
2
4
10
86
16
14
12
18
20
2
10
8
6
4
14
12
18
16
20
S
A
L
T
L
E
V
E
L
R
E
A
D
I
N
G
(
µ
g
c
m
-
2
)
ACTUAL SALT LEVEL
(µg cm
-2
)
35°C
15°C
25°C