CORROSION RESISTANCE OF HASTEllOY®AllOYS - Haynes ...

HYDROCHLORIC ACID
HASTELLOY® alloy B-2 is 'particularly well suited for equipment handling
hydrochloric acid at all concentrations and temperatures including the boiling
point.
It is important to note that corrosion behavior is affected by oxidizing
chemicals. The presence of ferric or cupric ions in solution greatly accelerates
attack, as can aeration of the hydrochloric acid. Even dissolved oxygen is
sufficient to increase the corrosion rate for alloy B-2.
"
HASTELLOY alloy C-276 is resistant to all concentrations of hydrochloric
acid at room temperature, and is used successfully up to about 120 deg. F (49
deg. C). Dissolved oxygen is not a strong enough oxidizer to passivate alloy C­
276, and a decrease in rates is observed when oxygen is removed from the
system.
HASTELLOY alloys G-3 and G-30 have only limited usefulness in
hydrochloric acid service. Acceptable corrosion behavior is exhibited in dilute
concentrations, but at concentrations greater than 5 percent, the upper limit of
utility is reduced to about 100 deg. F (38 deg. C).
HAYNES® alloy No. 25 and MULTIMET® alloy are resistant to
hydrochloric acid in all concentratrions at room temperature. (See page No.
86.)
ISOCORROSION DIAGRAM*
HASTELLOY® Alloy B-2
Resistance to Hydrochloric Acid
250
Corrosion rates in parentheses are in mm/year.
125
0-5 mpy,
100
u.. 0
C!J 200 5 mpy
w (0.13) w
0 0
w I w
a: a:
=> =>
l- I-
e:{ 5-20 mpy 75 e:{
a: (0.13-0.51) a:
w
w
a...
a...
~ 150 ~
w
w
l- I-
\
100
~
5 mpy
(0.13)
0-5 mpy
(0-0.13)
0 10 20 30 40
CONCENTRATION, WEIGHT PERCENT
\
50
"
•All test specimens were solution heat-treated and in the unwelded condition.
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