|
ADVANTAGES OF Zr OVER OTHER MATERIALS
As shown previously in Figure
1, zirconium's corrosion superiority under certain
operating conditions makes it the best choice as a construction
material for use in sulfuric acid environments. Table
1 below compares the corrosion resistance of zirconium
with titanium in sulfuric acid. While the corrosion of titanium
is lower with aeration and the presence of oxidizers, the
corrosion of zirconium is very low in all these conditions.
In Table 2, zirconium is compared with other alloys
for corrosion resistance in sulfuric acid; this table shows
why zirconium is used in low concentration / high temperature
and high concentration conditions.
TABLE 1: CORROSION OF ZIRCONIUM VS. TITANIUM IN
SULFURIC ACID
| Concentration
|
|
Temperature
|
Corrosion
Rate (mpy) |
| (weight
%) |
Gas
|
°
F |
Ti
|
Zr
|
| 3 |
Nitrogen
|
212 |
830 |
nil |
| 3 |
Air |
140 |
0.5 |
nil |
| 5 |
Nitrogen
|
212 |
1060 |
nil |
| 5 |
Air |
140 |
190 |
nil |
| 20 |
|
210 |
>2400
|
nil |
| 20* |
|
Boiling
|
5 |
nil |
*addition 16 g/L of Fe3+ (oxidizer)
TABLE 2: CORROSION OF ZIRCONIUM VS. OTHER ALLOYS
IN SULFURIC ACID
| |
Corrosion
Rate (mpy) |
| Concentration
(%) |
Temperature
(°
C) |
Zr
702 |
310L
SS |
316L
SS |
Alloy
B-2 |
Alloy
C-276 |
| 10 |
102* |
< 0.1 |
45 |
574 |
< 1 |
7.0 |
| 30 |
108* |
< 0.1 |
1,137 |
> 5000 |
2 |
55 |
| 55 |
132* |
0.1 |
<350,000 |
>10,000 |
1.89 |
295 |
| 55 |
168 |
19.6 |
--- |
--- |
37 |
212 |
| 2 |
225 |
< 0.1 |
--- |
--- |
14.9 |
39.7 |
| 5 |
232 |
0.1 |
--- |
--- |
110 |
153 |
| 10 |
225 |
0.1 |
--- |
--- |
1,023 |
661 |
* Boiling Point
Four of Six 1
2 3
4 5 6
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