Nickel Insitute - Nickel Alloys in Organic Acids & Related Compounds

Chloride is a commonly encountered contaminant in citric acid solutions. The effect on the austenitic stainless steels of this contaminant in 20% aqueous citric acid is shown in Table LXX. At levels up to 500 ppm of chloride, no significant general corrosion occurs on stainless steel

with such solutions. However, the presence of chlorides in combination with an acid create potential problems of pitting and stress-corrosion cracking particularly in cre- vices and other stagnant areas in the equipment.

TABLE LXVIII

Corrosion of Metals by Aqueous Tartaric Acid Solutions

Conditions: Laboratory tests without aeration or deaeration except as noted.

Corrosion Rate

2 26 (79) 21 –

5 26(79) 21 –

10 60(140) 100(212) 6 6 Aerated Aerated

25

30

50

57 54(129) 10 Field lead. yacuum yap.

%Tartaric Acid Temperature ºC (ºF) Test Period, days Other

35(95) 6 Aerated

103(217) 2 –

35(95)

60(140) 100 (212)

26(79)

60(140)

35(95)

60(140) 100(212)

6

6

6

11

11

6 6 Aerated Aerated Aerated 6

Aerated

Aerated Aerated

–

–

Alloy

mm/y mpy mm/y mpy mm/y mpy mm/y mpy mm/y mpy mm/y mpy mm/y mpy mm/y mpy mm/y mpy mm/y mpy mm/y mpy mm/y mpy mm/y mpy mm/y mpy mm/y mpy

Type 304 Stainless Steel Type 316 Stainless Steel CARPENTER alloy 20 INCONEL alloy 600 ELGILOY Titanium Zirconium Vanadium C71000 (80-20 Cupro- nickel) C71500 (70-30 Cupro- nickel)

–

–

–

–

–

–

–

–

–

–

Nil Nil .03 11 – – – – Nil Nil – – – – – –

–

–

–

–

–

–

–

–

–

–

–

–

–

–

–

–

–

–

– – – – – –

– – – – – –

– – – – – –

– – – – – –

– – Nil Nil – – – – Nil Nil Nil Nil .01 0.4

– – .01 .4 – – – – Nil .1 Nil Nil .04 1.5

– – .01 0.2 – – – – Nil 0.1 Nil <0.1 .48 19

– – Nil Nil – – – – Nil Nil Nil Nil – –

– – .01 .02 – – – – Nil 0.1 Nil Nil – –

– – Nil 0.1 – – – – Nil Nil Nil <0.1 – –

– – – – – –

– – – – – –

– – – – – –

– – – – – –

– – Nil Nil – – – – Nil Nil Nil Nil – –

– – .01 0.4 – – – – Nil Nil Nil Nil – –

– – .05 2.1 – – – – .01 0.5 Nil Nil – –

– –

– –

.06 2.4 –

– – –

– –

–

–

–

–

–

–

–

–

–

–

–

–

.02 0.8

–

–

–

–

–

–

–

–

–

–

–

–

–

–

–

–

–

–

–

–

–

–

–

–

–

–

.04 1.6

–

–

–

–

–

–

–

–

–

–

–

–

–

–

–

–

.03 1.2

.05 1.8

–

–

–

–

–

–

–

–

References 19, 46, 50

TABLE LXIX

Corrosion of Metals by Citric Acid

Corrosion Rate

% Citric Acid

Type 316 Stainless Steel

Test

C71500 (70-30 Cupro-nickel)

INCOLOY alloy 825

INCONEL alloy 600

MONEL alloy 400

CARPENTER alloy 20Cb-3

Temperature Period

Nickel 200

Copper

ºC

ºF

Days mm/y

mpy

mm/y

mpy

mm/y

mpy

mm/y

mpy

mm/y

mpy

mm/y

mpy

mm/y

mpy

mm/y

mpy

1

26

78.8

44

–

–

–

–

–

–

.01

2

Nil

Nil

–

–

–

–

–

–

2

26

78.8

7

–

–

–

–

–

–

.06

2.2

–

–

–

–

–

–

–

–

26

78.8

21

–

–

–

–

–

–

.16

6.2

–

–

.06

2.5

.07

2.8

–

–

5

16

60.8

30

–

–

–

–

–

–

.02

.9

.03

1.1

–

–

–

–

–

–

30

86

7

–

–

–

–

–

–

.12

4.9

–

–

.02

.8

–

–

–

–

60

140 216

7 3

– –

– –

– –

– –

–

–

.13

5

– –

– –

– –

– –

– –

– –

– –

– –

7

102

09

3.5

–

–

10

100

212

6

–

–

–

–

–

–

–

–

–

–

–

–

–

–

.01

.2

15

66

150.8

3

–

–

–

–

–

–

.10

4.1

.07

2.7

–

–

–

–

–

–

100

212

2

–

–

–

–

–

–

.11

4.2

–

–

–

–

–

–

–

–

20

Boiling

45

Nil

Nil

–

–

–

–

–

–

–

–

–

–

–

–

–

–

25 30

100

212

6

– –

– –

– –

– –

– –

– –

– –

– –

–

–

–

– –

–

–

Nil

.1

26

78.8

11

.04

1.5

–

–

–

–

–

60

140

11

–

–

–

–

–

–

–

–

.19

7.4

–

–

–

–

–

–

Boiling

7

–

–

–

–

–

–

.22

8.8

.21

8.4

–

–

–

–

–

–

50

20

68

1

–

–

–

–

–

–

–

–

.53

2.1

–

–

–

–

–

–

100

212

6

–

–

–

–

–

–

–

–

–

–

–

–

–

–

Nil

Nil

Boiling

6 7

– –

– –

– –

– –

– –

– –

–

–

–

–

– –

– –

– –

– –

.14

5.5

58

26

78.8

Nil

.1

Nil

.1

–

–

90

194

2

–

–

–

–

53

21

–

–

–

–

–

–

–

–

–

–

Boiling

1

–

–

–

–

–

–

.43

16.8

.16

6.2

–

–

–

–

–

–

61

60

140

30

–

–

–

–

02

0.6

.01

.5

.02

.9

–

–

–

–

–

–

–

–

–

–

06

2.4

–

–

–

–

–

–

–

–

–

–

60-78*

42-64 107.6-

37

147.2

65

Boiling

30

.21

8.1

.12

4.8

.79

31

.19

7.3

.11

4.2

–

–

–

–

–

–

*Field test in evaporator during concentration of the acid. References 19, 49, 51

Page 55