4.3 Influence of water quality on corrosion resistance
This chapter is intended to provide an overview of the corrosion resistance of stainless steels and soldering
materials in tap water at room temperature. The table lists several important chemical components, but the
actual corrosion is a very complex process that is influenced by many different components in combination
with each other. This table is therefore a considerable simplification.
Explanations:
"+" = Good resistance under normal conditions
"0" = Corrosion can occur, especially if other factors are rated as 0
"-" = Use not recommended
Plate material
Soldering mate-
rial
Water content
Concentra-
tion (mg/l or
ppm)
Time limits
for analysis
AISI
304
AISI
316
254
SMO
Cop
per
Nick
el
Stai
nles
s
Alkalinity (HCO
3
)
< 70
Within 24 hrs.
+
+
+
0
+
+
70-300
+
+
+
+
+
+
> 300
+
+
+
0/+
+
+
Sulphate
1)
(SO
4
2-
)
< 70
No limit
+
+
+
+
+
+
70-300
+
+
+
0/-
+
+
> 300
+
+
+
+
+
+
HCO
3
-
/ SO
4
2-
> 1.0
No limit
+
+
+
+
+
+
< 1.0
+
+
+
0/-
+
+
Electrical conductivity
< 10
µ
S/cm
No limit
+
+
+
0
+
+
10-500
µ
S/cm
+
+
+
+
+
+
> 500
µ
S/cm
+
+
+
0
+
+
pH
2)
< 6.0
Within 24 hrs.
0
0
0
0
0
+
6.0-7.5
+
+
+
0
+
+
7.5-9.0
+
+
+
+
+
+
> 9.0
+
+
+
0
+
+
Ammonium (NH
4
+
)
< 2
Within 24 hrs.
+
+
+
+
+
+
2-20
+
+
+
0
+
+
> 20
+
+
+
-
+
+
Chloride (Cl
-
)
See also table "Chloride content"
< 100
No limit
+
+
+
+
+
+
100-200
0
+
+
+
+
+
200-300
-
+
+
+
+
+
> 300
-
-
+
0/+
+
+
Free chlorine (Cl
2
)
< 1
Within 5 hrs
+
+
+
+
+
+
1-5
-
-
0
0
+
+
> 5
-
-
-
0/-
+
+
13
