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Formic
Acid
More
corrosive than acetic acid, formic acid is used in the production
of pharmaceuticals, dyes, and artificial flavors. The leather,
textile, rubber and pulp and paper industries also use formic
acid in their process.
Table
2. Corrosion Data for Formic Acid
|
Media
|
Concentration
(%)
|
Temp
(C° )
|
Corrosion
Rate (mpy)
|
| Formic
Acid |
10-98 |
35-Boiling |
<1 |
|
Formic (aerated) |
10-90 |
Room-100 |
<1 |
|
Formic + 5% sulfuric |
50, 70, 93 |
Boiling |
<1 |
|
Formic + 5% hydrochloric acid |
50, 70, 85 |
Boiling |
<1 |
|
Formic + 1% Cupric |
50, 70, 96 |
Boiling |
<1 |
|
Formic + 1% iron powder |
50, 70, 98 |
Boiling |
<1 |
|
Formic + 5% HI |
50, 70, 90 |
Boiling |
<1 |
|
Formic + 2% hydrogen peroxide |
50 |
80 |
<1 |
|
Formic + 4% hydrogen peroxide |
50 |
80 |
<1 |
Other Organics
Zirconium is used in a wide range of
organic media. These include sulfuric acid containing organic
process streams such as methyl methacrylate (MMA), methacrylic
acid (MAA), alcohols, hydroxyacetic (glycolic) acid, and rayon
production. Other organic process streams involving hydrochloric
acid include lactic acid, and methyl isobutyl ketone (MIBK).
Production of phenolic resins and adipic acid are other areas
that use zirconium extensively in production equipment.
A limiting condition for the use of
zirconium in organic process streams is maintaining minimum
water content. A minimum of 50-ppm water, for example, is
required for protection against hydriding in certain chlorinated
organic compounds. To prevent stress corrosion cracking (SCC)
in methanol solutions, with and without halogens or halides,
>2% water may be required.
Table 3. Corrosion Data
for Other Organics
|
Media
|
Concentration
(%) |
Temp
(C° )
|
Corrosion
Rate |
| Acetaldehyde |
100 |
Boiling |
<2 |
|
Acetyl Chloride |
100 |
25 |
>200 |
|
Aniline Hydrochloride |
5, 20
5, 20 |
35-100
100 |
<1
<2 |
|
Bromochloromethane |
100 |
100 |
<2
|
|
Citric Acid |
10-50
10,25,50
50 |
35-100
100
Boiling |
<1
<1
<5 |
|
Dichloroacetic Acid |
100 |
Boiling |
<20 |
|
Ethylene Dichloride |
100 |
Boiling |
<5 |
|
Formaldehyde |
6-37
0-70 |
Boiling
Room-100 |
<1
<2 |
|
Formalin |
100 |
98 |
<1 |
|
Hydroxyacetic Acid |
70 |
205 |
<1 |
|
Lactic Acid |
10-100
10-85 |
148
35-Boiling |
<1
<1 |
|
Methanol |
100 |
Boiling-200
|
Nil |
|
Methanol + 0.1% KI + 0.1% formic acid
|
99.8 |
65 |
Nil |
|
Melamine
|
100
100 |
260
427 |
<1
<1 |
|
Methanol + 1% KI |
99 |
200 |
<1 |
|
Oxalic Acid |
0-100 |
100 |
<1 |
|
Oxalic Acid + 41% sulfuric acid
|
17 |
74 |
<1 |
|
Oxalic Acid + 52% sulfuric acid
|
4 |
82 |
<1 |
|
Oxalic Acid + 52% sulfuric acid + 3%
nitric acid + 2.5% ferrous sulfate |
4 |
82 |
Gw* |
|
Phenol |
Saturated |
Room |
<5 |
|
Phenol + 11% hydrochloric acid
|
60 |
70 |
<1
|
|
Phenol + 27% hydrochloric acid
|
7.2 |
100 |
<1 |
|
Sodium Formate |
0-80 |
100 |
<2 |
|
Sodium Phenolsulfonate |
100 |
185 |
<1 |
|
Succinic Acid |
0-50
100 |
100
150 |
<2
<2
|
|
Tannic Acid |
25 |
35-100 |
<1
|
|
Tartaric Acid
|
10-50 |
35-100 |
<1 |
|
Trichloroacetic Acid |
10-40
100
100 |
Room
Boiling
100 |
<2
>50
>50 |
|
Tetrachloroethane |
100 |
Boiling |
<5 |
|
Trichloroethylene |
99 |
Boiling |
<5 |
|
Urea |
50 |
Boiling |
<1 |
|
Urea Reactor Mixture (45% urea, 17%
ammonia, 15% carbon dioxide, 10% water) |
Mixture |
193 |
<1 |
|
Methyl Sulfide |
100 |
21 |
<1
|
|
Methyl Sulfonic Acid |
40 |
60 |
<1 |
|
Methyl Sulfonic Acid + 500 ppm Ceric
+3 |
40 |
60 |
<1 |
|
Methyl Sulfonic Acid with 500 ppm Ceric
+4 |
40 |
60 |
<1 |
* Gained Weight
III. Safety
There is a special safety concern when
using zirconium. Reactive metals like zirconium can develop
pyrophoric films. Normally zirconium corrodes uniformly and
all the zirconium is converted to zirconium oxide. If corrosion
rates are low, <5 mpy, there is time to react all the zirconium
uniformly.
Under certain conditions, usually involving
high corrosion rates under static conditions, it is possible
that the corrosion process will liberate discrete un-oxidized
zirconium grains. Under these conditions, the corrosion product
may become pyrophoric. To passify the un-reacted zirconium,
the trapped zirconium grains need to be completely oxidized
before opening the equipment to the atmosphere. This is achieved
by passing steam or hot air at 240°
C for 20 minutes or 120° C
for 3 days through the equipment to make sure all the zirconium
in the corrosion product is reacted.
IV. Summary / Corrosion Lab and Other Wah
Chang Resources
As demonstrated above, zirconium can
be the best alternative for material selection in many organic
applications. Longer equipment life, reduced maintenance downtime,
and higher purity product streams are all possible with the
proper application of zirconium, making it the most cost-effective
option when compared with other alloys.
Although, zirconium has proven its
outstanding corrosion resistance performance in a wide variety
of organic environments, the best way to determine zirconium’s
suitability for a particular environment is to perform a corrosion
test. Zirconium corrosion test kits are available from Wah
Chang for use in on-line process equipment. These tests can
show how zirconium will hold up under actual process conditions.
For further information or any questions
regarding the use of zirconium in organic applications, please
contact Technical Services at Wah Chang.
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