Nickel Insitute - Nickel Alloys in Organic Acids & Related Compounds

TABLE LV

Corrosion of Annealed and Heat Treated Alloys in Dicarboxylic Acids

Laboratory test in 10% boiling dibasic acid stated for 5 days without aeration or deaeration. Acetic acid added for comparison.

Corrosion Rate

Oxalic Acid

Maleic Acid

Phthalic Acid

Acetic Acid

Alloy

mm/y

mpy

mm/y

mpy

mm/y

mpy

mm/y

mpy

.94

37

.01

0.2

.01

0.2

.01

0.3

Type 316L Stainless Steel (annealed) Type 316L Stainless Steel (Heat treated)* CARPENTER alloy 20Cb-3 (annealed) CARPENTER alloy 20Cb-3 (Heat treated)* INCOLOY alloy 825 (annealed) INCOLOY alloy 825 (Heat treated)

.66

26

.01

0.2

.01

0.3

Nil

<0.1

.58

23

.01

0.2

Nil

<0.1

Nil

<0.1

.23

9

Nil

<0.1

Nil

0.1

Nil

0.1

.51

20

Nil

0.1

Nil

<0.1

Nil

<0.1

.38

15

.02

0.7

Nil

0.1

.05

1.8

*650 ºC (1200 ºF) for one hour, water-quenched.

steel can be reduced essentially to zero in even boiling 10 per cent acid by the addition of approximately 50 ppm of iron as ferric oxalate. 35 As noted in Table LV, the dibasic acids above oxalic in the series are much less corrosive. Maleic acid, m.p. 130 ºC (266 ºF), can be considered as the next homologue, and the acid is innocuous in aqueous solution when compared to oxalic acid.

oxalic acid. As with corrosion in the monobasic acids, the addition of molybdenum is very beneficial. Nickel-base alloys containing molybdenum exhibit the best resistance of all alloys in hot, aqueous oxalic acid (Table LVI). Less costly alloys, such as Type 316 stainless steel, can be used for specific applications at temperatures somewhat higher than ambient in aqueous solutions of the acid. Streicher has shown that the rate of attack on Type 304 stainless

TABLE LVI

Corrosion of Alloys by Oxalic Acid

Laboratory tests without aeration or deaeration except as noted

% Oxalic Acid Temp. ºC ºF Test Period (days)

1 Boiling Boiling 1.5

10 25 77 7

10 35 95 6

10 50 122 6

10 80 176 0.1-10

10 Boiling Boiling 2-10

30 60 140 11

Corrosion Rate

Alloy

mm/y mpy

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

mm/y

mpy

mm/y mpy

–

–

–

–

– – – – – – – – – – – – – –

– – – – – – – – – 1 – – – – –

–

–

–

–

63.5

2500

– – – – – – – – – – – – – – –

– – – – – – – – – – – 8 – – – –

Type 430 stainless steel Type 304 stainless steel Type 316 stainless steel Type 216 stainless steel ALLEGHENY alloy AL-6X* Act CN-7M HASTELLOY alloy C-276 HASTELLOY alloy B ELGILOY** Titanium Vanadium C71500 (70-30 Cupro-nickel)

.03 (1)

1 (1)

.81 (1)

32 (1)

1.52 (1)

60 (1)

2–16–14.48 (1)

85–570 (1)

.81

32

– – – – – – – – – – – – –

– – – – – – – 1 – – – – – –

– – – – – – – – – – – –

– – – – – – – – – – – –

– – – – – – – – – – – – – –

– – – – – – – – – – – – – –

– – – – – – – – – – – – – –

– – – – – – – – – – – – – –

.18– 2.44

7–96

1.52

60 11

.28 .18 .25 .13 .10

7

10

5 4

.03

11.68

460 10 (2)

950–

.03

24.1–73.7

.25 (2)

5.46 (2)

215 (2)

.41 (2)

4 (2)

–

–

.20

.63 .48 .05 .23

25 19

WAUKESHA No. 23 WAUKESHA No. 54 WAUKESHA No. 88 KROMARC 55 Multiphase MP35N

2 9

–

–

–

–

–

–

–

–

–

–

.10

4

–

–

(1) Type 304L material heat treated at 675 º C (1250 º F) for 1 hour (2) Aerated.

*Trademark of Allegheny Ludlum Steel Corporation. **Trademark of Elgiloy Co.

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