AAON SA-028 - Appendix A - Heat Exchanger Corrosion Resistance

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Appendix A - Heat Exchanger Corrosion Resistance
Corrosion Resistance of Copper and Stainless Steel in Brazed Plate Heat Exchangers
- Points to Measure and Check in a Water Analysis
The resistance guide below provides the corrosion resistance of stainless steel type AISI 316 and
pure Copper (99.9%) in water, to a number of important chemical factors. The actual corrosion is
a very complex process influenced by many different factors in combination.
Explanations: + Good resistance under normal conditions
0 Corrosion problems may occur especially when more factors are valued 0
- Use is not recommended
Water
Containing
Concentration
(mg/l or ppm)
Time Limits -
Analyze Before
AISI
316
SMO
254
Copper
Alloy
Nickel
Alloy
Alkalinity
(HCO
3
-
)
< 70
Within 24 Hours
+
+
0
+
70-300
+
+
+
+
> 300
+
+
0/+
+
Sulfate (SO
4
2-
)
< 70
No Limit
+
+
+
+
70-300
+
+
0/-
+
> 300
0
0
-
+
HCO
3
-
/ SO
4
2-
> 1.0
No Limit
+
+
+
+
< 1.0
+
+
0/-
+
Electrical
Conductivity
< 10µS/cm
No Limit
+
+
0
+
10-500 µS/cm
+
+
+
+
> 500 µS/cm
+
+
0
+
pH
< 6.0
Within 24 Hours
0
0
0
+
6.0-7.5
0/+
+
0
+
7.5-9.0
+
+
+
+
> 9.0
+
+
0
+
Ammonium
(NH
4
+
)
< 2
Within 24 Hours
+
+
+
+
2-20
+
+
0
+
> 20
+
+
-
+
Chlorides (Cl
-
)*
< 300
No Limit
+
+
+
+
> 300
0
+
0/+
+
Free Chlorine
(Cl
2
)
< 1
Within 5 Hours
+
+
+
+
1-5
+
+
0
+
> 5
0/+
+
0/-
+
Hydrogen
Sulfide (H
2
S)
< 0.05
No Limit
+
+
+
+
> 0.05
+
+
0/-
+
Free (aggressive)
Carbon Dioxide
(CO
2)
< 5
No Limit
+
+
+
+
5-20
+
+
0
+
> 20
+
+
-
+
*See Also Chloride Content Table