kupdf.com_corrosion-handbook-on-stainless-steel.pdf

Sandvik Steel Sandv Steel C or orros rosion ion Ha Handbook Staii nless Ste Sta Stee els

Sandvik Steel Corrosion Handbook Stainless Steels

Sandvik Steel Corrosion Handbook Stainless Steels

AB SANDVIK STEEL S-811 81 Sandviken, Sweden Phone +46 26 26 30 00 Fax +46 26 25 17 10 www.steel.sandvik.com

Corrosion Tables © 1999 Page 1 – 45 AB Sandvik Steel Page 1 – 88 Avesta Sheffield AB and AB Sandvik Steel ISBN: 91-630-2124-2 Photoes front page: Pär Hedqvist Printed in Sweden Sandvikens Tryckeri

Corrosion Handbook for stainless steels PREFACE

When first introduced in 1994 this “Corrosion handbook for stainless steels” replaced an earlier edition published by Jernkontoret, Stockholm, Sweden, which was jointly produced by the Scandinavian manufacturers of stainless steel in 1979. Being a unique source of information for material specialists and designers, it has been highly appreciated. Continued materials research has resulted in new grades and improved properties of the existing grades. New corrosion tests are continuously being carried out, often reflecting the more aggressive environments to which the materials are being exposed. A combination of these factors has motivated a revision of the corrosion tables. The present revised and extended edition is the result of a cooperation between Avesta Sheffield AB and AB Sandvik Steel in Sweden. As an introduction, a series of papers are presented on the corrosion theories in connection with stainless steels. Corrosion testing, different steel types and grades, general aspects on different applications, as well as fabrication aspects are also discussed. These papers are then followed by corrosion tables and graphs describing the resistance of various materials to different environments (in alphabetical order), concentrations and temperatures. We are pleased to see that this work, which is based on more than 70 years' experience in solving corrosion problems with stainless steel, is made available to industry. It is my belief that this corrosion handbook will be a valuable tool for all material specifiers when designing the process plant and equipment of today and tomorrow.

Sandviken, March 1999

Per Ericson President, AB Sandvik Steel

SANDVIK

STEEL

CORROSION

HANDBOOK

Contents Introduction Corrosion of metals Different corrosion types and test methods

General corrosion Galvanic or two-metal corrosion Intergranular corrosion Pitting corrosion Crevice corrosion Stress corrosion cracking High temperature corrosion

Introductrion Oxidation Catastrophic oxidation Sulphidation Carburisation and nitration Molten metal corrosion Halogen corrosion Erosion-corrosion Applications Composite tube applications Stainless steels

Introduction Austenitic stainless steels and Duplex stainless steels Manufacturing programme

Special stainless steel grades Nickel base alloys Titanium Zirconium Applications for stainless steels

Chemical industry Urea production Oil and Gas industry Corrosion in petroleum refining and petrochemical applications The pulp and paper industry Fabrication Constructional design Bending Expanding into tube sheets Surface properties Steel grades – Manufacturing programme

I:8 I:9 I:10 I:10 I:11 I:12 I:14 I:16 I:17 I:21 I:21 I:22 I:22 I:22 I:23 I:23 I:23 I:23 I:23 I:25 I:26 I:26 I:27 I:28 I:28 I:29 I:30 I:30 I:31 I:31 I:35 I:37 I:40 I:43 I:46 I:46 I:48 I:48 I:49 I:50

Corrosion tables

Isocorrosion diagrams: Acetic acid Chromic acid Citric acid Fluosilicic acid Formic acid Hydrochloric acid Hydrochloric acid with chlorine Hydrofluoric acid Lactic acid Nitric acid Oxalic acid Phosphoric acid – with chloride additions – with fluoride additions Sodium hydroxide Sulphuric acid – deareated – naturally areated – with chloride additions – with iron sulphate – with chromic acid – with copper sulphate Tartaric acid Physical tables

II:1 II:2 II:16 II:16 II:20 II:22 II:24 II:24 II:26 II:30 II:35 II:39 II:41 II:42 II:42 II:54 II:59 II:59 II:60 II:60 II:61 II:61 II:70 II:74

Density, modulus of elasticity and coefficient of linear expansion of stainless steels II:74 Thermal conductivity of stainless steels II:74 Physical properties of certain chemical elements II:75 Temperature conversion table II:76 Chemical elements II:78 Degrees Baumé II:79 Vapour pressure of water II:79 pH values: alkaline solutions II:80 acid solutions II:80 foods II:80 substances in human body II:80 hydrochloric acid, nitric acid and sulphuric acid solutions II:81 Relationship between weight-% and density, molarity, volume-%, kg/litre and degrees Baumé: acetic acid II:81 ammonium hydroxide II:82 formic acid II:82 hydrochloric acid II:83 nitric acid II:83 phosphoric acid II:84 potassium hydroxide II:84 sodium hydroxide II:85 sulphuric acid II:85 Glossary Disclaimer

II:86 II:88

7

S-037-ENGHA ISBN: 91-630-2124-2

AB Sandvik Steel, SE-811 81 Sandviken, Sweden, Phone +46 26-26 30 00 www.steel.sandvik.com

SANDVIK STEEL CORROSION HANDBOOK

1. The first part of this handbook constitutes an introduction to corrosion together with a brief description of stainless steel grades and special metals. Different corrosion types are discussed comprehensively in connection with some relevant test methods, some of which have been used to gather the data in the latter part of the handbook. Fabrication of stainless steel products is described and some advice in this area is given. Finally, a number of applications are reviewed for which the corrosion problems are discussed in more detail and materials selection for especially demanding environments is suggested. The corrosion tables comprising the last half of this corrosion handbook have been produced in cooperation between AB Sandvik Steel and Avesta Sheffield AB. They are intended to constitute a guide to the corrosion resistance of the included stainless steel grades. Different levels of corrosion rates are shown together with indications of local attack, such as pitting. A large number of different environments are included and in many cases also a wide range of concentrations and temperatures. You are hereby provided with a useful key in

Introduction the choice of material for a certain application. The data can also be used when the corrosion resistance of used or recommended grades is discussed with regard to changes in concentration or temperature. To further illustrate the corrosion resistance of stainless steel grades several diagrams have been included, showing isocorrosion curves etc. The subject of stainless steel corrosion is a vast area and cannot be completely covered in this handbook. For detailed information about corrosion types in different environments several references may be given [cf ref 1-4]. Standard tests of corrosion resistance are thoroughly described in reference 5. Corrosion research is an ever ongoing process with innumerable articles being published every year. The state of the art can be found in the journals focussing on corrosion, of which reference 6 to 9 are recommended here. Lectures are also continuously being published within AB Sandvik Steel concerning the properties and experiences of Sandvik steel grades and special metals. A catalogue of titles can be requested from your nearest Sandvik Steel sales office.

1.

M.G. Fontana, Corrosion Engineering, 3rd Edition, McGraw-Hill, 1987.

2.

Corrosion Mechanisms in Theory and Practice, P. Marcus and J. Oudar, Eds., Marcel Dekker Inc, 1995.

3.

H.H. Uhlig and R. Winston Revie, Corrosion and Corrosion Control, 3rd Edition, John Wiley and sons, 1985.

4.

G. Wranglén, An Introduction to Corrosion and Protection of Metals, Institut för metallskydd, 1972.

5.

Corrosion tests and standards: Application and Interpretation, John Baboian, Ed., American Society for Testing and Materials, 1995

6.

Corrosion Science

7.

British Corrosion Journal

8.

Corrosion, NACE

9.

Werkstoffe und Korrosion

I :8


2.

Corrosion of metals

C o r r o s i o n i s g e n e r a l l y defined as a dissolution of

rosion and has become what is usually called stainless. The

a material due to a reaction with the surrounding environ-

reason is that the chromium forms an oxide layer on the sur-

ment. Most metals are in a thermodynamically unstable form,

face, and this layer sufficiently protects the metal from the

and corrosion often means that there exists a thermodynamic

surrounding environment when the chromium content is

driving force for recombination of the unstable elemental

about 13% or more. Other common elements that are used to

form to the chemically stable oxidized form found in nature.

improve the ability to passivate are molybdenum and nitrogen.

Many metals can maintain their unstable form, in spite of the thermodynamic driving force, thanks to their ability to pas-

When passivity cannot be maintained, due to a too aggressive

sivate. Passivation means that the surface of the metal is cove-

environment, the metal will be exposed to the surrounding

red by a, usually very thin, layer of corrosion product. This so

environment and a dissolution of the metal may take place.

called passive layer, which in most cases consists of an oxide

The attack initiates at weak spots on the surface, such as

film, separates the metal from the surrounding environment

scratches or contaminated areas, and is then continued as

and hence the corrosion resistance is considerably increased.

local or uniform corrosion. The rate at which the dissolution

The ability to passivate for pure iron is limited, which means

takes place is usually measured in terms of e.g. mm/year. In

that iron will show a relatively low corrosion resistance in

the case of local attack, such as pitting or stress corrosion

most media. The ability to passivate is however increased by

cracking, the corrosion rate is not a relevant parameter.

alloying with chromium. At a chromium content of about

Instead, any signs of local attack should be seen as a warning

13% the alloy shows a considerably better resistance to cor-

not to use the material under those specific circumstances.

Heat-exchanger tube of Sanicro 29 heavily attacked by erosion corrosion on the inside of the bend. The cause was sand in the cooling water.

I :9


3.

Different corrosion types and test methods

W h e n c o r r o s i o n o c c u r s the attack is characterised

The most common environments where general corrosion

by the way in which the metal is dissolved. Many forms of

occurs on stainless steels are strongly acidic or alkaline solu-

corrosion exist, and here the most common types occurring

tions. The specific composition of the environment is crucial

for stainless steels are described.

for the corrosiveness, and may be drastically changed if oxidising or reducing compounds are added. The performance of stainless steel grades can vary considerably in the same envi-

General corrosion General corrosion is characterised by a uniform attack over

ronment and to different additives. It is therefore of great

the surface of the material when exposed to a corrosive me-

importance that the environment where a product is to be used

dium. It is therefore possible to define a corrosion rate (r),

is thoroughly characterised. When this is done a suitable

often stated as a mass loss per unit surface area (g/m2h), or as

material can usually be selected. The economic advantages of

a mean metal loss per unit time (mm/year). The latter unit is

choosing a grade with high corrosion resistance, sometimes

used for tabled data as well as in the diagrams presented in

acquired at a higher price per kilo, can be illustrated by esti-

this book. It is, however, sometimes desired that the corrosion

mations of the life cycle cost.

rate should be expressed in mils/year (milli-inch per year or mpy). Corrosion rates in mm/year are easily translated to rates

TESTING OF GENERAL CORROSION

Testing of general corrosion is usually performed by exposing

in mpy from the relationship:

samples to the corrosive environments over specific time

r (mpy) = 39.4 x r (mm/year)

intervals and calculating the corrosion rates from weight los-

Isocorrosion diagrams illustrate the resistance of metallic

ses. To avoid irregularities from the initiation period the sam-

materials to general corrosion. Each isocorrosion line repres-

ple is weighed after each period and the first value is dis-

ents a fixed corrosion rate and the dependence of concentra-

regarded. At least two samples of each material should be

tion and temperature on the corrosive medium can be shown.

used and the corrosion rate is determined as the calculated mean value for two or more periods.

F -, % 1.5

2302b

H3PO4 = 70 % H2PO4 =4 % 3+ Fe = 0.45 %

1.0

Sanicro 28

0.5 Alloy 20Cb3 Alloy 904

Figure 2. Sandvik 5R60 (middle) and 5R10 (right) tested in 60% H 2SO 4 at 100°C for 24 hours. Unexposed test coupon to the left.

Alloy 825

0 200

400

600

800 Cl , ppm

Figure 1. Curves representing a corrosion rate of 0.3 mm/year for Sanicro 28 and three other alloys in wet-process phosphoric acid at 100°C. The combined effect of chloride and fluoride is shown.

I :10


Another way to calculate corrosion rates is to use an electrochemical technique. The corrosion current, I, is proportional to the amount of oxidised metal if no competing oxidation reaction is taking place. By this method changes in corrosion rate can be registered whilst adding corrosives or inhibitors, raising the temperature etc.

Galvanic or two-metal corrosion

Table 1. Approximate EMF-values in sea water Material

Free corrosion potential / volts SCE*

Magnesium

-1.6

Zinc

-1.0

Aluminium alloys

-1.0 to -0.75

Mild steel, c ast iron

-0.65

Copper

-0.34

Admiralty brass

-0.30

When two different metals are used in the same environment

F er r i ti c s t ai nl es s s t ee l, 4 30 - 0 .2 4

they often obtain different potentials. If they are in contact or

Nickel 200

-0.2 to -0.1

otherwise electrically connected a sufficient potential differ-

3 04 - ty pe s t ai nl es s s te el * *

- 0 .0 8

316-type stainless steel**

-0.10 to 0

Titanium

-0.05 to +0.05

Platinum

+0.2

ence might produce a flow of electrons between them. The more noble material becomes cathodic and the less corrosion resistant anodic. This often results in increased corrosion of the anodic material and a decreased attack of the cathodic.

*Saturated Calomel Electrode

This phenomenon is used for cathodic protection, where a so

** For passivated material values well above +0.1 can be obtained

called sacrificial anode is connected to the material to be protected. When coupling different stainless steel grades potential differences are generally too small to cause galvanic corrosion problems.

As an example of this steel bolts in a more noble copper sheet corrode more quickly than steel sheet with copper bolts, in the same environment. When the metals are in contact with one another the rate of anodic corrosion often decreases with

The ranking of materials with regard to potential can be found

increasing distance from the cathode, i.e. the material loss is

in galvanic or EMF-series (electromotive force). Low EMF

greatest close to the cathode. This is especially pronounced

values are found for magnesium and zinc, among others, whe-

when the surrounding electrolyte has low conductivity.

reas copper, platinum and gold have high values. Standard EMF values have been calculated for standard conditions but the order between metals often differs depending on the environment. For metals such as titanium or aluminium, which form very protective oxide layers even at room temperature in air, the low standard values of potentials can seldom be reproduced. For a more realistic ranking of metals galvanic series have been determined empirically for special environments, such as sea water (see table 1). When evaluating the risk of galvanic corrosion it is of great importance that the correct

There also exists a related corrosion type sometimes called indirect galvanic corrosion. In this case the metals need not be in direct contact. Instead the more noble metal corrodes by uniform corrosion and its metal ions are transported, e.g. in solution, to the surface of the anodic metal. They are there reduced and at the same time enhanced oxidation of the anodic metal occurs. The corrosion of the anodic metal can accelerate even further if the noble metal atoms on its surface can act as sites for more efficient reduction of other species, e.g. from the electrolyte.

potential values are used, determined for the right solution

C O R R O S I O N T E S T S F O R G A L VA N I C C O R R O S I O N

and temperature. In the same way, when sacrificial anodes are

Tests for galvanic corrosion are rarely performed as this is

used, and thus galvanic corrosion is desired, the material

more for the designer's concern. It might, however, be very

which functions as an anode can become cathodic to the

useful to check the metal combinations in the environment to

material to be protected in certain environments. This is the

be used. The corrosion rates for the metals in contact can then

case when zinc is used for the protection of steel, if the con-

be compared to the rates of uniform corrosion of the isolated

centrations of carbonates become too high. Galvanic corro-

metals in the same environment. Another possibility is to

sion of stainless steels in the passivated state is unusual.

measure the potentials of each metal against a reference elec-

When in connection to other metals, such as copper or carbon

trode, or the potential difference between them, in the environ-

steel, stainless steels will generally be cathodic.

ment in question. It is important, however, to remember that increased corrosion does not automatically follow from dis-

The relative area of the anode compared to the cathode greatly

similar potentials. Generally a potential difference of several

influences the corrosion rate. The larger the cathode area is

tens of volts is required and in addition to this a decrease in

compared to the anode area the faster the corrosion will be.

galvanic corrosion rate is often observed if passivation occurs.

I :11


Intergranular corrosion

To avoid intergranular corrosion, resulting from chromium

Intergranular corrosion is characterised by preferential dissolu-

carbides, one can choose a grade with lower carbon content,

tion at the grain boundaries. Usually intergranular corrosion

one alloyed with stabilising elements like titanium or niobium

occurs in stainless steels that have been exposed prolonged

(typically in grades like 321, 347 etc), or avoid heating in the

time to certain temperatures (typically 600-900°C), so that a

sensitising temperature range. The latter can be difficult to

formation of chromium-rich carbides in the grain boundaries

achieve in practice when, for example welding is carried out.

has taken place. Immediately adjacent to these carbides, in the

Nitrides may also precipitate in grain boundaries during heat

outer parts of the grains, there will be a chromium depleted

treatment, and in molybdenum-bearing stainless steels also the

zone. These regions, which consequently have a lower corro-

intermetallic phases, such as

sion resistance than the rest of the alloy, will suffer from pref-

temperature-transformation) the time required for the forma-

erential dissolution.

tion of precipitates during heat treatment is illustrated.

χ

and σ. In a TTT-diagram (time-

TESTING FOR RESI STANCE TO INTERGRANULAR CORROSION

Several methods exist for the testing of intergranular corrosion. Generally an oxidising, acidic solution is used, but pH, potential and temperature depend on the method used. Because of their differences one must choose a method which is suitable for the steel grade and grain boundary composition to be tested. The applicability for some ASTM tests to austenitic stainless steels are summarised in table 2. Intergranular corrosion in stainless steels may result from precipitation of carbides, nitrides or intermetallic phases. Only in the most highly oxidizing solutions can intergranular attack be caused by intermetallic phases. When a test is to be restricted to carbides, in a material containing nitrides or intermetallic Figure 3. Microstructure of a material surface with intergranular attacks.

phases, a less oxidizing solution should therefore be chosen. Corrosion potentials of wrought stainless steel in different test

solutions and the detectable phases are summarised in table 3.

Table 2. Applicability of some ASTM standard practices in A 262 for testing of intergranular corrosion in austenitic stainless steels PRACTICE

TEST

TEMPERATURE

TIME

APPLICABILITY

EVALUATION

A

Oxalic Acid Etch

ambient

1.5 min

Chromium carbide

Microscopic: classification

sensitization only

of etch str ucture

Chromium carbide

Weight loss/

Screening Test B

Ferric Sulphate

boiling

120 h

50% Sulphuric Acid C

D

E

65% Nitric Acid

corrosion rate Chromium carbide

Weight loss/

and sigma phase

corrosion rate

Chromium carbide

Corrosion ratio

3% Hydrofluoric

in 316, 316L, 317

compared to solution

Acid

and 317L

annealed specimen

Chromium carbide

Examination for

10% Nitric Acid

6% Copper Sulphate

boiling

70°C

boiling

240 h

4 h

24 h

16% Sulphuric Acid

fissures after bending

Metallic Copper F

Copper Sulphate 50% Sulphuric Acid Metallic Copper

I :12

boiling

120 h

Chromium carbide

Weight loss/

in cast 316 and 316L

corrosion rate


HUEY TEST

STRAUSS TEST

The Huey test (ASTM A262, practice C) means that the

A common way of investigating the resistance to intergranu-

samples are boiled for 5 periods of 48 hours each in 65% nitric

lar corrosion is to heat treat the sample in the sensitising tem-

acid. The corrosion rate is calculated for each period from

perature range and carry out a Strauss test (SIS 117105, DIN

weight losses. For further information the maximum depth of

50914, ASTM A262 practice E etc.). The samples are boiled

attack may be measured, but this is not included in the stand-

in a solution of copper sulphate and sulphuric acid with cop-

ard evaluation. The environment is strongly oxidising and

per turnings. The test time (15, 20 or 24 hours) depends on the

should only be used as a check on whether the material has

standard used and the evaluation consists of a visual exam-

been correctly heat treated. The Huey test can therefore not be

ination for cracks originating from intergranular corrosion

used to compare the corrosion resistance of different steels to

attacks. The samples are usually bent before examination. If

other, less oxidising, environments. This test is suitable for the

cracks are suspected to arise from poor ductility a similar but

detection of chromium depleted regions as well as intermetal-

unexposed sample should be used for reference.

lic precipitations, like sigma phase, in the material.

Temperature, °C (°F) 800 (1470)

1302b

AISI 304

700 (1290)

Sandvik 3R12

600 (1110)

500 (930) 0.05

0.1

0.5

1.0

5.0

10

50 100 Annealing time, h

Figure 5. Time-temperature-sensitisation curve for Figure 4. Intergranular corrosion testing

AISI 304 and Sandvik 3R12 (AISI 304L). Results from

by the Huey method.

testing in boiling Strauss solution (12% H 2SO 4 , 6% CuSO 4). There is a risk of intergranular corrosion to the right of the curves.

Table 3. Corrosion potentials and detectable phases for wrought stainless steels in some acid solutions SOLUTION

CORROSION

AUSTENITIC STEELS

FERRITIC STEELS

POTENTIAL

Cr-carbide

Carbides and Nitrides

Sigma

(VSCE) 65% HNO 3

0.75-1.0

yes

Fe 2 (S O 4 ) 3

0.6

yes

H 2 SO4

Intermetallics

Fe-Cr

Fe-Cr-Mo

316, 316L, 3 1 7, 3 1 7L , 3 2 1

yes

yes

yes

no

yes

yes

yes

(321 possible exception)

(not σ or χ in unstabilised Fe-Cr-Mo alloys)

CuSO 4

0.35

yes

no

yes

yes

no

H 2 SO 4 As above but

0.1

yes

no

yes

yes

no

10% HNO 3 3% HF

-0.1-0.3

yes

no

yes

yes

no

5% H 2 SO 4

-0.6

yes

no

no

yes (not σ or χ in unstabilised grades)

no

with metallic Cu

I :13


Whenever the origin of cracks is questionable a detailed

the pit. Often a lid of corrosion products is formed leaving a

metallographic examination should be performed to deter-

very small hole at the surface which prevents dilution of the

mine the absence or presence of intergranular attack. This test

pit contents. Finally, the metal surface surrounding the pit

method can detect chromium depleted regions in the material

mouth becomes cathodically protected through electron

but cannot detect other possibly detrimental inhomogeneities,

migration from the pit.

like precipitations of sigma phase. Figure 5 shows a so called time-temperat time-temperature-sen ure-sensitisat sitisation ion curve, curve, where the minimum minimum time for heat treatment before intergranular attacks appear is shown as a function of temperature.

In many cases pitting corrosion is not detected until it has caused severe severe damage, damage, such as a complete complete penetration penetration in sheet or tube material. This is due to the very small pit holes formed on the surface and to the fact that the metal surfaces in many applications become covered with precipitates from

STREICHER TEST

The Streicher Streicher test (ASTM A262 practice practice B, ASTM G28) G28) requires the samples to be immersed in a boiling solution of ferric sulphate and sulphuric acid for a period of up to five days. The test can detect chromium depleted regions in stainless steels but cannot be used to detect susceptibility to intergranular attacks associated with sigma phase in wrought

process fluids or with thick layers of more or less protective corrosion products. The corrosion products from a pit attack are often found to create a lid on top of of the pit, with only a very small opening. When examining the metal surface for pits it should therefore be thoroughly cleaned in order to reveal the pitted areas.

stainless steels. The evalution of samples is done by calculating the corrosion rates and may also be completed completed with the measured depths of attack.

Pitting corrosion When pitting corrosion occurs the attack is localised to small areas on the surface where a break through of the passive layer takes place. This will create crea te pits and possibly eventually holes in the metal. This form of corrosion is often more detrimental than general general corrosion, corrosion, due to the local dissolution dissolution which can cause rapid penetration of the metal thickness. thickness. The nucleation time for pits depends on factors such as the ox-

Figure 7. Test coupons after pitting corrosion test

idising idising character of the environm environment, ent, the concentration concentration of

according to ASTM G48. From the left to the right:

aggressive ions such as chlorides, pH and the alloy composicomposi-

Sandvik Sandvik 3R60, 3R60, Sandvi Sandvikk 2RK65, 2RK65, SAF 2304, 2304, SAF 2205 2205

tion of the metal. The properties properties of the surface, surface, for instance

and SAF 2507.

the presence of initiation sites at defects defects and inclusions, also effect the nucleati nucleation on time. time. During During the attack, attack, howeve however, r, sev-

PRE-VALUES

eral mechanisms act together to result in an autocatalytic pro-

The chromium content of stainless steel grades is important

gress of pit growth. The environment within the pit becomes

and alloying with molybdenum and nitrogen has proved very

increasingly aggressive, due to anion selective diffusion into into

beneficial for the pitting resistance. From experimental data, relations between elemental composition and pitting resist-

Corrosion products H2O+O2

_ OH

ance have been developed. These values are generally called _ Cl

_ OH

H2O+O2

PRE, pitting pitting resistance resistance equiv equivalents, alents, and can be used for for an approximative ranking of stainless steel grades. Several forms

Passive

e _

_ Cl + H

2+ Fe 2+ Fe _ Cl + H

film

are known of which one often used expression is below.

_ e

PRE = %Cr + 3.3% Mo + 16%N Metal

In the duplex austenitic-ferritic stainless steels the nitrogen content content is high, which promotes promotes the pitting pitting resistance. resistance. The high nitrogen content in SAF 2205 (nominal (nominal value: 0.18%) 7326

Figure 6. A corrosion pit with some possible chemical reactions.

I :14

showed

compared to some other 2205 type grades with a minimum of 0.08% N (for UNS S31803), is therefore beneficial. In the


duplex duplex grades grades the PRE might, might, howeve however, r, differ differ between the the

T E S T I N G F O R P I T T I N G R E S I S TA TA N C E

two phases. To avoid this duplex steel grades must be de-

Ordinary methods using weight losses are not recommended

veloped with a balanced composition so that the elements of

for pitting tests because the overall material loss may be very

importance are partitioned to equal benefit in the two phases.

small even though severe pits have developed. Evaluating the

This is the case for SAF 2507, for which PRE in both phases

number of pits, their depths or localisation can give give useful

is greater than 40.

information about the mechanisms of initiation and growth, but is not adequate for evaluation of pitting resistance. It is

Table 4. Minimum PRE-values for some Sandvik

therefore preferable to simulate conditions which result in pit

stainless steel grades

initiation to provide a relevant means of assessing resistance

S teel gr ade

P R E ( a s d e fi n e d a b o v e )

to this type of corrosion attack. This is done by exposing the

S a nd v i k 3 R1 2

18.7

test material to an aggressive environment for a certain time.

S a nd v i k 3 R6 0

25.6

If corrosion pits are observed the material has failed.

S a nd v i k 2 RK 6 5

33.0

S AF 2 304

24.1

S AF 2 205

35

S AF 2 507

41

S a ni c r o 2 8

37.7

THE ASTM G48-TEST

One immersion test method for pitting corrosion is the ASTM G48A-test, G48A-test, where samples samples are immersed in a 6% Fe FeCl Cl3 solution. This solution is very corrosive due to the simultaneous presence of chloride ions and oxidising ferric ions. The temperature is held constant (e.g. at 22±2 or 50±2°C) and the recommended time for exposure is 72 hours. After cleaning the

THE EFFECTS OF ALLOYING ELEMENTS ON PITTING RESISTANCE

The effects on pitting corrosion resistance of all oying with for

samples are weighed and the surfaces are examined for pits. CPT DETERMINATIONS

instance molybdenum or nitrogen nitrogen have been investigated, investigated, but

The temperature and the presence of oxidising agents are

the picture is not yet completely clear. In the case of alloying

important parameters for pitting corrosion. A number of test

with molybdenum improved metal passivation has been

methods have therefore been developed to determine the cri-

found. When pitting attack occurs the molybdenum assists in

tical values values for these. The critical pitting pitting temperature, temperature, CPT, CPT, is

repairing the passive layer so that pit nucleation is stopped.

a value often requested. It should be noted that CPT values

According to one theory molybdate ions are formed from dis-

are specific for the environment and the test method used a nd

solved molybdenum. The molybdate ions then remain at the

these must therefore always be reported. CPT can be deter-

outer surface of the diffusion layer so that it becomes cation

mined by a modified version of the ASTM G48 test described

selective. selective. The aggressi aggressive ve anions, anions, such as chlorides, chlorides, are there-

above. A sequence of test periods are used at increasing tem-

by prevented from reaching the surface. At the interface

peratures. Between immersion periods the samples are

between the oxide and the diffusion layer anion selectivity

removed, cleaned and examined for for pits. The minimum tem-

prevails so that oxide growth can continue. After the initiation

perature at which the material experiences pitti ng corrosion is

of attack increased amounts of molybdate ions have also been

defined as the CPT.

detected in pitted areas. CPT can also be determined electrochemically. The most The effects of molybdenum seems to be enhanced by nitrogen

common ways are either to use a potentiodynamic method

which influences the molybdate concentrations at the s urface.

and measure at which temperature the break-through potenti-

This has been explained by the production of ammonium ions

al drops, or to use a constant constant potential (potentiostatic method)

which increase increasess the pH which, which, in turn, turn, makes the the formation formation

and measure the temperature at which the current increases

of molybdate ions more likely. Surface analysis has also

drastically. A discrepancy exists between results from diffe-

proved that iron dissolution is increased with increased nitro-

rent methods but they are both frequently used to study differ-

gen amounts, amounts, whereas whereas the dissolution dissolution of of chromium chromium and

ences in pitting resistance of stainless steels.

molybdenum decreases. In alloys with increased nitrogen amounts the passive films have been found to contain higher

Figure 8 shows the critical pitting temperature for different

ratios of chromium in the outer layer. Below this exists a thin

alloys measured potentiostatically at +300 mV SCE and with

layer enriched in nitrogen, nickel and molybdenum. molybdenum.

varying chloride concentrations. The potential +300 mV SCE is often found in natural sea water. Figure 9 shows the same

I :15


figure for other alloys and with a higher applied potential (+600 mV mV SCE), which correspo corresponds nds to a potential potential often

CPT, C ( F), 600 mV SCE 100 (210) °

°

6185b

found in chlorinated sea water. 90 (195) CPT, C ( F), 300 mV SCE 100 (210) °

°

SAF 2507 4159b

80 (175) 80 (175)

SAF 2205

70 (160) 60 (140)

AISI 316

25 Cr – Duplex 60 (140)

40 (105)

AISI 304

20 (68)

40 (105) 0 (32)

SAF 2205

50 (120)

0.0 1

0.02

0.05

0.10

0 .20

0 .50

Cl – ,% 3 5

1.0 2 .0 Cl – , weight-%

6

9

10

15

12

15

20 25 NaCl, weight-%

Figure Figure 8. CPT-values CPT-values for SAF 2205, AISI 304 and AISI

Figure 9. CPT-values at varying concentrations of sodi-

316 at varying concentrations of chloride. A potentio-

um chloride, from 3 to 25%. A potentiostatic determi-

static determination at +300 mV SCE and pH=6.0.

nation at +600 mV SCE.

Crevice corrosion This form of corrosion is in principle the same as pitting cor-

the material on location crevices should be opened and the

rosion,, but occurs in crevi rosion crevices, ces, e.g. betwe between en flange flange joint joints, s,

surface be thoroughly cleaned. In practice it is very difficult

under deposits on the metal surface or in welds with incom-

to entirely eliminate crevices in constructions. Crevice corro-

plete penetration. A concentration cell is created with the

sion often occurs at lower temperatures and at lower chloride

anode in the crevice and the cathode on the outer surface. This

concentrations than for pitting corrosion. Up to a certain

corrosion form may be hard to spot, in the same way as for

limit, the risk for attack increases the more narrow the

pitting, as it occurs in concealed places. When When examining

vice is.

Figuree 10. Schematic illustration of crevice corrosion Figur under a washer.

I :16

cre-


The mechanism of stress corrosion cracking is not well

TEST FOR CREVICE CORROSION

Evaluation of crevice corrosion resistance may be done accor-

understood. This is mainly due to the specific features of SCC

ding to the ASTM G48B test. As in the pitting test (practice

being the result of a complex interplay of metal, interface and

A) samples are immersed in a 6% FeCl3 solution. Before immersion crevice formers with specified properties are

environment properties. As a result of this different combina-

mounted on the samples. The critical temperature for crevice

most reliable information is obtained from empirical experi-

corrosion, CCT, may be determined in the same way as for

ments. During SCC the material does not undergo general

CPT. One method for this is described in the MTI-2 standard,

corrosion and the phenomenon is sometimes considered t o be

where the temperature is increased by 2.5°C. For reasons of

one of activation/passivation interaction. It has been found

investigating specific crevice formers, e.g. when the extrac-

that cracks often initiate in trenches or pits on the surface,

tion of aggressive ions may be suspected, modified tests are

which can act as stress raisers. The isolated times for pit ini-

sometimes performed.

tiation, pit growth, crack initiation and fracture may, however,

tions of solution and stress are seldom comparable and the

differ considerably between different materials. Temperature ( °C) 6247b

CPT (°C)

90 80

6Mo+N austenitic

CCT (°C)

SAF 2507

*25Cr - 3Mo - .2N

70 25 Cr Duplex*

60 50 40 30

904L

SAF 2205

20 10

Figure 11. Comparison of CPT- and CCT-values for some stainless steels (obtained by the modified ASTM G48 method).

Stress corrosion cracking Stress corrosion cracking (SCC) is an environmentally assisted cracking process, where a specific environment combined with tensile stress induces cracks on the metal surface. Stress corrosion cracking often occurs at increased temperatures, i.e. above 60°C, but cases where SCC has occurred at lower temperatures exist. The most common media where stress corrosion cracking occurs are chloride containing solutions, but in other environments, such as caustics and polythionic acid, problems with SCC may also appear. Some enviroments that may cause stress corrosion cracking of stainless steels are listed below. Table 5. Some environments where stainless steels

Figure 12. Stress corrosion cracking of a tube.

In some cases crack initiation has been associated with the formation of a brittle film at the surface. The film developed at grain boundaries might, for instance, have lower ductility due to a different metal composition than the bulk material. At a certain film thickness and under stress this brittle film will crack and expose the underlying metal. New film growth will proceed with subsequent continued crack growth and so forth. The developed crack tip has a small radius and will develop a very high stress concentration. Even so, the stress condition alone is not sufficient for crack growth, but corrosion still plays a very large part. It has been shown experimentally that stress corrosion cracking can be stopped when applying cathodic protection, i.e. when corrosion is stopped but the stress conditions remain unchanged.

are prone to stress corrosion cracking. Acid chloride solutions Seawater Condensing steam from chloride waters H 2 S + chlorides Polythionic acid (sensitised material) NaCl-H 2 O 2 NaOH-H 2 S

I :17


Crack growth direction

σ

Crack growth direction

σ

H++ eH

σ

H H H H

n + M e n + M e

Figure 13. Transgranular stress corrosion crack in

σ

Anodic stress Time to cracking corrosion cracking

Hydrogen embrittlement

Sandvik grade 2RE69 after autoclave testing in 1000 ppm chloride at 250°C. Immunity

Cracking may be either transgranular (TGSCC) or intergranular (IGSCC) or, perhaps most usual, a combination of both.

Anodic current M Men+ + n e-

Cathodic current 2e- + 2H+ 2H

The material microstructure and alloying components are of

7325

major importance for crack paths as well as for SCC resist-

Figure 14. Possible mechanisms of cracking due to

ance. Alloying with Ni can make materials less prone to SCC

SCC and HE respectively.

and the duplex microstructure of the austenitic-ferritic grades is also beneficial. Standard austenitic stainless steels, like AISI 304 and AISI 316, are generally prone to SCC in chlo-

SULPHIDE STRESS CRACKING

ide containing environments at temperatures above 60°C,

Sulphide stress cracking (SSC) might be defined as a variant

except at very low chloride contents, and therefore higher

of HE, but is sometimes treated as a special corrosion type.

alloyed austenitics or duplex stainless steels should be used.

Sulphides are hydrogen-evolution poisons and as such prevent the hydrogen atoms formed on the metal surface from

HYDROGEN EMBRITTLEMENT

Hydrogen embrittlement (HE) is sometimes stated to be a

pairing up and dissolving as H2 into the surrounding solution. SSC has been found to cause severe problems especially in

kind of SCC. This might, however, lead to serious misunder-

the oil and gas industry. A standard for material requirements

standings as many discrepancies exist. Perhaps most import-

in so-called sour environments has therefore been developed:

ant is that HE cannot be reduced by cathodic protection, but

NACE MR0175. Among the acceptable steel grades are SAF

might instead increase under such circumstances. The reason

2205, SAF 2507 and Sanicro 28. New grades can be accepted

for this is that HE is caused by the penetration of atomic

in NACE MR0175 after successful testing according to one of

hydrogen into the metal structure. This, in turn, might occur when reduction of H+ is taking place on the metal surface,

four methods described in NACE TM 0177. (See also chapter 7, oil & gas industry.)

e.g. during cathodic protection in acidic environments. Several deposition techniques, such as electroplating, also

TEST METHODS

involve reduction processes at the metal surface with the fol-

The stress corrosion cracking resistance can be tested in a

lowing risk of hydrogen penetration and embrittlement. To

laboratory by different methods. Usually a constant load, a

avoid this, treated articles are often baked before use to remo-

constant elongation or a slow strain rate is applied to the

ve the hydrogen. The risk for HE is increased for harder

sample in a chloride containing environment. Several stan-

metals, but the tendency to hydrogen cracking decreases with

dards have been developed regarding the stress application for

increasing temperature. Some differences between HE and

SCC testing. U-bends, C-rings and bent-beam specimen are

SCC are illustrated in figure 14.

some examples of this.

I :18


Figure 17 shows examples of results from constant load tests according to a modified ASTM G36 method, where 40% CaCl2 at 100°C is used as the corrosive medium. The time to failure versus load is recorded and a threshold stress is determined, below which SCC does not occur. In figure 18 results from constant load tests (stress equals yield strength) are presented for which a spring was used to apply the stress. The mounted samples were tested in an autoclave at different temperatures and chloride concentrations. This method has been verified to correspond to practical cases, as illustrated in the figure.

Figure 15. U-bent

Figure 16. Constant

sample for stress

load SCC testing in 40%

corrosion testing with

CaCl 2 at 100°C, using

constant strain.

weights.

Temperature, C ( F) °

°

1373b

300 (572) SCC 250 (482)

Constant load can be applied to the sample simply by the use of weights as shown in figure 16. Another way is to strain the sample with the aid of a spring. Regardless of method certain requirements must always be met by the testing equipment. Crevices and galvanic corrosion must be avoided and all exposed parts must be resistant to any kind of corrosion in the

200 (392) 150 (302) No SCC 100 (212)

CaCl2

environment. 50 (122)

Time to fracture, h 60

4229b

0.0001

0.001

0.01

0.1 SCC

50 SAF 2205

1

10

_ % Cl

No SCC

Laboratory test, aerated _ solution Service experience, Cl +S/H2S _ Service experience, Cl

Figure 18. A compilation of practical experience and 40

laboratory SCC test data of 3RE60. AISI 304L

AISI 316L

30

The drop evaporation test is another common method to measure SCC-resistance. With this method a specimen is electrically heated and subjected to a constant load and at the same

20

time a dilute sodium chloride solution is dripped onto the specimen. At the heated surface the chloride solution evaporates, leaving a highly concentrated chloride environment. The test

10

is continued until the specimen cracks or up to a specified time, usually 500 hours. In the same manner as in the modifi0.

0.

0. 0. 1. Stress/Tensile strength 100 C (210 F) °

Figure 17. Results of SCC test with constant load in

°

ed ASTM G36-method the time to failure versus load is recorded and a threshold stress is determined below which SCC does not occur.

40% CaCl2 at 100°C (210°F) with aerated test solution.

I :19


In slow strain rate testing (SSRT) the stress over the sample is

7590

continously increased. The strain rate must be chosen cor-

(ultimate) tensile strenght

rectly so that SCC is induced. Too low values result in

inert environment

repassivation of the attacks, whereas too high values give purely mechanical fractures. This method of loading resulting in continuous breaking of the passive layer and monotonically increasing load is very aggressive and does not reflect the conditions in practical service of the material. The results from an SSRT test are conveniently presented in a stressstrain curve, in the same way as mechanical tests (figure 19).

°

A / F , s s e r t s . m o N

corrosive environment

fracture

In this way several parameters can be compared for tests in corrosive and inert environments. The ratio between such parameters is often used to rank the susceptibility to SCC for

0 0

different materials.

Nominal strain (I - I0)/I0

Figure 19. Stress-strain curve for corrosive and inert

For the testing of sulphide induced cracking in sour service the NACE standard TM 0177 may be used. A choice between four methods is given, in which stress is applied in different ways. The test solution is selected to give hydrogen absorption conditions equal to that expected of the most severe well environment. It should have a partial pressure of hydrogen sulphide of 1 bar, 5% chlorides and pH=3. The test temperature is set to 20-25°C and the samples must resist a period of up to 30 days without cracking.

I :20

environment respectively.


4.

High temperature corrosion

Introduction

However, a good oxide scale will not last for ever, as the scale

The temperature region for high temperature steels, ranges

will continue to grow until it reaches a certain thickness. At

from about 400˚C up to temperatures where the mechanical

this point stresses due to the differences in volume between

properties of the alloy will be severely reduced. High temper-

the scale and the alloy will become so large that the scale will

ature applications are found in various processes, as for

crack. The cracks will cause the oxide to spall off and then the

example wire annealing, combustion/incineration, hydro-

protection of the scale is gone. The spalling can be measured

carbon cracking, air heating (recuperators) and shieldings. In

and is often used to compare and rank the alloys. The spalling

these applications the selection of an alloy becomes difficult,

temperature is measured by heating the alloy in air at increas-

as the material is subjected not only to corrosive chemicals,

ing temperature steps for a certain time and the temperature

but also to a degeneration due to the temperature. That is, the

where the weight change of the alloy exceeds a pre-defined

alloy may become brittle due to structural changes, e.g. formation of sigma-phase or 475°C embrittlement. This is

value is set as the scaling temperature (usually this value is 1.5 g/m2h). For comparison, the scaling temperature for car-

particularly so in the case of ferritic steel with a Cr-content

bon steel is about 550˚C and for 353MA (25% Cr, 35% Ni)

higher than 15%, and in the temperature ranges 400-800˚C.

the scaling temperature is about 1225˚C. The maximum ser-

Furthermore, for materials that are designed for carrying a

vice temperature of an alloy is usually set 50˚C below the

load, own weight or pressure, the creep properties will beco-

scaling temperature.

me a dominating factor. In most cases a compromise between the desired properties must be made, as no single alloy is likely to have excellent values in all these fields (e.g. high Cr is good for corrosion, but bad regarding structural stability). Most common material temperatures in high temperature applications are in the range 400-900˚C. At these temperatures the alloy will react with the surrounding gas phase and degenerate chemically, forming what is referred to as corrosion products. The formation rates of these products are strongly temperature dependent. In aqueous solutions a 10 times higher corrosion rate is not uncommon for a temperature change of 30˚C. The same 10 fold change (or worse) may occur with a 20˚C change under high temperature conditions. Note that if the temperature is too low it may be diffi-

Figure 1. Rapid oxide growth (dark) in 18-8 material

cult for a protective oxide scale to form. This can become a

caused by too high temperatures. The oxide growth rate

problem particularly in applications where the material is

has been fast enough to form pieces of metal “islands”.

internally cooled, e.g. furnace tubes.

This oxide scale is not protective!

Most of the corrosive elements can be found in the upper right corner of the periodic table. The elements in this area have similarities in chemistry and will, thus, have similar reactions paths. The corrosion product formed may be "beneficial" or "detrimental" to the alloy, depending upon the specific prod-

As there are large differences, not only in the volume between the oxide and the alloy but also in the thermal expansion coefficient scaling may become a severe problem when the process includes a temperature cycle.

uct formed. In practice the life time for an alloy relies on it's

Scaling is not the only mechanism that can disrupt a protect-

ability to form a dense, adherent and continuous oxide layer

ive oxide. In many applications a melt deposit may also be

with a low growth rate. If other products are formed, i.e.

formed, especially in combustion processes. This melt can

sulphides, carbides, nitrides, or halides, the scale will be less

dissolve the oxide layer and open up the alloy for further and

protective or even more corrosive than no scale at all.

rapid corrosion. This particular reaction is often referred to as

I: 21


“hot corrosion”. Hot corrosion is a well known phenomena in the gas turbine industry. There is an on-going argument on the mechanism of this type of corrosion and s o far the only agreement is that there are two types of hot corrosion, which appear at different temperatures. In many cases studied it appeared that the onset of rapid corrosion was dependent on some degree of thermal cycling and that there was an indefined initial period before the corrosion rate increased. (See also catastrophic oxidation below.) In the subsequent text some corrosion reactions will be discussed, but first it should be mentioned that there is a great difference between high temperature corrosion and “wet” corrosion. This means that material developed for high temperature applications may not have as good corrosion resistance at low temperatures and in “wet” applications as it has in the high temperature range.

Oxidation The main corrosion reaction is oxidation. Oxidation of an alloy may occur at any temperature (the oxidation rate will increase with the temperature) if the amount of oxygen is high enough. The advantage with oxidation is that the oxide layer formed may serve as a protection from further corrosion, that is, if the oxide layer formed is dense, continuous, and adherent. Some alloying elements like Al, Si, and Cr may form a dense layer, and of these three elements Al and Si will form the most effective oxide scale. Unfortunately, the amount of Al or Si needed in the alloy for forming this oxide scale will make the alloy rather brittle and it's fabrication difficult. In carbon steel and in low alloyed steel, iron is the main oxide former. Iron may form a rather dense oxide, Fe2O3, which is protect-

Figure 2. Catastrophic oxidation of a Mo-rich duplex alloy, after 24h in 1060˚C

then the material will be destroyed within a very short period of time. This behaviour is often referred to as “catastrophic oxidation”. Other alloying elements that are sensitive to catastrophic oxidation are V, Pb, W, Ta, and Nb.

Sulphidation In many high temperature processes sulphur is present, e.g. in most processes where coal or oil is combusted. The chemistry of sulphur is rather similar to that of oxygen, and sulphur will thus react in competition with oxygen. However, sulphur will not form such a dense layer as in the case of oxides and moreover, the melting point of the sulphides formed may sometimes be several hundred degrees lower than that of the oxide, e.g. Ni3S4, melting point ~650˚C. If Ni3S4 is formed in the grain boundaries this will also decrease the strength of the alloy. Hence Ni-containing alloys should be avoided in sulphurous environments if they are unable to form a protective oxide scale.

ive. However, if the temperature is higher than 550˚C, wüstite

In a sulphur-containing atmosphere where sufficient oxygen

(FeO) is formed. This phase is porous, it is not protective and

is present to allow an oxide scale to form the corrosion resist-

rapid oxide growth will occur causing the low scaling temper-

ance is determined by the properties of that layer, but if cracks

ature of carbon steel. To enhance the protective effects of the

(see scaling above) start to form in the oxide layer, then sul-

oxide scale small amounts of RE (Reactive Elements, = Sc, Y,

phur will attack at these points. This means that the corrosion

La, Ce, Pr, Nd, Pm, Sm, (sometimes also called REM, Rare

resistance in sulphur containing atmospheres will depend on

Earth Metals) may be added to the alloy. It is not fully clear

the scaling temperature of the alloy, and the maximum service

why this should occur, but several investigations have shown

temperature will be dependant upon both the scaling temper-

that these small (< 0.1%) additions result in reduced growth

ature and the amount of sulphur in the gas. On the other hand,

rate and improved adherence of the Cr- and Al- oxides.

if the alloy cannot form a protective oxide the corrosion resistance will be greatly reduced and more dependant upon

Catastrophic oxidation

the alloy composition. Under these conditions it is favourable

Even if the formation of oxides in general is beneficial for the

to use an alloy that is high in Cr and has either no Ni (e.g.

alloy, there are some oxides that should be avoided. Oxides,

4C54, provided that embrittlement is not a problem) or a

such as for example MoO3, have rather low melting points, or

lower level of Ni (e.g. 253MA).

may form compounds with other oxides that have low melting points, especially in static (non-flowing) systems. The melts formed may dissolve the remaining oxide layer and

I: 22


Carburisation and nitration

Halogen corrosion

In some applications the atmosphere is reducing with a high

Halogen Halogen (i.e. F, F, Cl, Br and I) containing containing gases are often often very

content of carbon (C) or nitrogen (N), e.g. in wire annealing, annealing,

aggressive against all metallic materials. The ones of greatest

ethylene ethylene furnaces furnaces,, carbon carbon black black prod producti uction, on, or steamsteam-

interest are F and Cl. The former is regarded to be the more

methane reforming. In these processes the material temper-

corrosive one while the latter is more frequent. If the envir-

ature may be as high as 900-1150˚C. If carbon is used to

onment is reducing, reducing, Ni and Cr generally improve improve the corro-

generate a reducing environment the carbon species in the

sion resistance. resistance. In oxidising oxidising environ environments, ments, Cr, and especially especially

atmosphere atmosphere may react react with the the alloy, alloy, forming forming carbides. carbides.

Mo and W, W, are detrimental due to their tendency to form vol-

Sometimes the carburisation reaction will occur rapidly and

atile oxychlorides. The general mechanism of corrosion is the

this phenomena phenomena,, “metal dusting” dusting” is mainly observed observed in waste waste

same as for oxidation and sulphidation. High chloride vapour

heat boilers in steam reforming processes in the temperature

pressure can result in penetration and disruption of the oxide

range 500-800˚C. Even if metal metal dusting does not not occur, the

scale. Voids may be formed under the scale as the chlorides

formation of carbides is detrimental as this reaction often

evaporate. There has been limited study of halogen reaction

catalyses coking, and the coke may may then block the tube.

with metals and general material performance criteria are still

In some wire annealing processes cracked ammonia is used to

under development.

create a non-oxidising environment. In this case the nitrogen activity is high, which will lead to the formation of nitrides nitrides in the alloy. The chemistry of the alloy may change due to carburisation/nitridation, as it is often one alloying element that reacts with the carbon/nitrogen, e.g. Cr. Cr. This element will then be tied up in the precipitates and will not be able to form a protective oxide scale. Furthermore, the bulk material below the surface will be depleted in Cr and this will reuce the possibility of oxide formation. A heavy carbon or nitrogen pickup may also embrittle the alloy as the precipitation of the carbides/nitrides are concentrated at the grain boundaries. Also, the creep properties and and the ductility will be affected by the carburisation/nitridation reaction. The resistance to carbon and nitrogen pickup is improved by increased Ni-content. In oxidising environments

Erosion-corrosion Erosion can enhance or retard corrosion attacks; increasing them by removing the protective layer or decreasing them by the removal removal of corrosive deposits. deposits. similarly, similarly, corrosion may increase or decrease erosion rates; increasing them by attacking the eroded surface or decreasing them by forming an oxide layer that is more erosion resistant then the parent metal. This means that in addition to having a good resistance against the corrosive atmosphere, materials exposed to erosion must be be able to develop an adherent, ductile and selfhealing oxide layer. The addition of Rare Earth Metals has a beneficial influence on all these three oxide layer properties. Application areas where erosion may occur are for example fluidized bed combustion (FBC) and cement production.

strong oxide oxide forms such as Cr, Cr, Al, and Si are beneficial. beneficial. Al Al is

There are still a lot of work to be done to determine the effects

of special interest, particularly in environments environments where carbu-

of erosion-corro erosion-corrosion sion on different different materials, hence, no specific

risation is the main problem.

data is available on erosion-corrosion of alloys.

Molten metal corrosion

Applications

The main corrosion mechanism here is either massive or

The high temperature applications that Sandvik targets are

selective dissolution. Some general observations are that

presently presently recuperators, recuperators, muffle muffle tubes, thermocoup thermocouple le protection protection

austenitic Ni-Cr-Fe alloys dissolve more rapidly with increas-

tubes, boiler tubes and ethylene furnace tubes. The selection

ing Ni-content, and that ferritic Fe-Cr stainless steels tend tend to

of the material in each application is very much dependent on

be more resistant. Note that the embrittlement caused by the

the environment. environment. For For example, the atmosphere in a muffle

liquid metal is more hazardous than corrosion. This embrittle-

tube may be oxidisin oxidising g (air), reducing reducing (cracked (cracked ammonia), ammonia), or

ment is more pronounced for melts containing silver (Ag),

carburizing e.g. bundy tube production). Each environment

copper copper (Cu), and zinc (Zn). (Zn). When When molten, molten, these metals metals will

demands specific properties of the alloy. In table 1-3 some

penetrate austenitic alloys intergranularly and may cause rup-

Sandvik recommendations on material selection are pre-

ture within a few seconds. Cases where this has been reported

sented, varying with application and environment.

are for example, example, welding of stainless steel to galvanised galvanised carbon steel, steel, weld cracking cracking due to copper copper contam contaminatio ination, n, and cracking caused by copper containing anti-seize compound.

I: 23


POWER BOILERS

be susceptible to the corrosion attack, whilst corrosion resis-

Power Power utility boilers, boilers, especially especially those burning burning biomassbiomass- or

tant alloys often have insufficient strength at the temperatures

fossil fuels which often contain high levels of sulphur and

involved. Tube failures result in having to shut down the

chlorine, represent one of the most demanding demanding applications

power station.

for stainless steel tubes. The outer tube surface is attacked at high temperature by the combustion products with differing

A proven solution is to use composite tube. There are two

corrosion and/or erosion mechanisms.

main areas of application application:: evaporat evaporator or tubes and the super super

The inside surface is often subjected to steam oxidation cor-

heater/reheater tubes.

rosion: rosion: and the material material is expected to support support high high loads

In the evaporator evaporator section, tubes typically have a highly corro-

resulting from high internal steam pressure – often under con-

sion sion resistan resistantt outer outer layer, layer, 25Cr20 25Cr20Ni Ni varian variant, t, and a load load

ditions where creep is a significant factor.

bearing carbon- or low alloy inner component. In the super-

Currently Currently,, temperatures temperatures and pressures pressures are generally generally being increased, with the intention of improving thermal efficiency and to reduce pollution. Conventional high strength alloys can

heater/reheater elements a typical solution utilises a high alloy outer component component,, e.g. 310Nb, 310Nb, Sanicro Sanicro 28, alloy 825, or alloy 625 bonded to a creep resistant steel inner component.

Table 1. Maximum working temperature in different gases. Temp C

500

°

60 0

700

800

90 0

100 0

11 00

In air (High humidity may lower temperature 50-150 C) °

353 MA 253 MA 310, Sanicro 31HT, 4C54 304H, 316H, 321H In oxidising sulphurous gases

353 MA 4C54 253 MA 310 Sanicro 31HT 304H, 316H, 321H In reducing sulphurous gases

4C54 253 MA 310 353 MA Sanicro 31HT 304H, 316H, 321H The maximum temperature is depending on t he level of flue gas impurities (S, Na,V)

Table 2. Structural stability. °

Temp C

4 00

500

600

700

8 00

Grade

Sanicro 31HT*

γ

253 MA

σ phase

353 MA

σ phase

309S

σ phase

310S

σ phase

4C54

I: 24

475 C-embrittlement °

σ phase

90 0

1000

1175


Composite tube applications

actual material temperature may be some 20-50˚C higher than

In many cases high temperature materials from Sandvik Steel

the water, water, or the steam temperature. temperature.

are delivered for applications where both corrosion resistance and pressure vessel approval must be fulfilled. Such applications are black liquor liquor recovery recovery boilers (BLRB): (BLRB): municipal municipal waste incinerators, and power power utility boilers. boilers.

This boiler is the heart of the pulp industry, industry, i.e. if the boiler is shut down, down, the whole plant plant must stop. There are high safety demands in this process because if a tube bursts, bursts, and water water contacts contacts the melt, melt, there is a high high risk

Table 3. High temperature corrosion properties A comparis co mparision ion between betwe en Sandvik S andvik High Temperature empera ture Steels and TP 310.

for a boiler explosion. The environment in a municipal waste incinerator boiler (MWB) is much more aggressive to metals that that in the BLRB, and thus the corrosion rates here are

Oxidati on

C a r b ur i s at i o n

N i t r i d i ng *

TP 310

0

0

0

3 53 MA

+ ++

+++

++

2 53 MA

+

+

0

For these two applications Sandvik has developed composite

S a ni c r o 3 1 HT

=

++

++

tube solutions. Composite tubes consist of two alloys that are

4 C54

0

– **

–

* in crac cracke ked d ammon ammonia ia atmo atmosp spher here. e. ** 4C54 has has very very good resi resistance stance to metal dusting corrosion. 0 = reference value + = superior to

high. If a tube bursts or fails here, the plant must be shut down down for repair which is costly.

co-extruded to form a tube with outer and inner components. The bonding between these components is a chemical metalto-metal bond (sometimes referred to as a metallurgical bond). One of the components is there to serve as the load

– = inferior to.

carrier and the other as a corrosion protection layer. The load carrier is often a carbon steel type 4L7 (SA210-A1) for tem-

A BLRB is a boiler about 30-70 m high where the floor and

peratures below 450˚C, a low alloyed carbon steel like HT8

the walls are made of panel welded tubes. The boiler is used

(T22) for temperatures temperatures up to 550˚C, 550˚C, or higher alloyed alloyed steel

to burn the residues from the wood cooking and to recycle the

like T91 for temperatures up to 600˚C.

cooking chemicals (mainly sulphides). The combustion of the residue is controlled in such way that the sulphides in the fuel (black liquor) will form smelt that accumulates at the bottom of the boiler. This smelt (now called green liquor) is then

In the BLRB's the combinations Sanicro 38/4L7 (floor), 3R12/4L7 (wall) and, 3RE28/HT8 (superheater) are recommended.

taken out through smelt spouts at the bottom of the boiler and

For waste incinerators the recommendations are 3R12/4L7,

processed further to be reused in the cooking. The tubes are

Sanicro 28/4L7 or Sanicro 63/4L7, 63/4L7, depending on on temperat-

water cooled, cooled, and the water/steam water/steam pressure pressure is generally be-

ures and type of pollutants in i n the fuel. There is on-going deve-

tween 60-100 bar. This will correspond to a water/steam

lopment of composite tube combinations for various applica-

saturation temperature of 250-300˚C in the walls and steam

tions.

temperatures of around 400-480˚C in the superheater. The

I: 25


5. Introduction

Stainless steels These alloys, the austenitic stainless steels, have an improved

Stainless steels is a designation for a group of iron-base alloys

formability, greater toughness and high temperature prop-

with such a composition that they are able to passivate, i.e.

erties, as well as improved weldability compared to ferritic

form a passive layer which protects the metal from the sur-

stainless steels. The physical properties will also change, e.g.

rounding environment, and thus hinder metal dissolution

fully austenitic stainless steels are non-magnetic.

(corrosion). The chief alloying element in stainless steels is chromium (Cr), which in concentrations above 12-13% forms a passive layer on the metal. Increasing the chromium content leads to a stronger passivity and thus a higher corrosion resistance. Chromium is a so called ferrite stabiliser, which means that chromium does not alter the structure of iron, which has a ferritic structure. The physical properties of an alloy with only chromium added therefore does not differ much from pure iron. These types of alloys are called ferritic stainless steels. Although chromium makes the steel stainless it cannot resist more aggressive environments, and the formability of ferritic stainless steels is limited. Other elements are therefore added

Molybdenum (Mo) has an effect similar to chromium with regard to structure and corrosion resistance. Molybdenum alloyed steels are what is usually called ”acid proof”, which refers to the beneficial effect of molybdenum on the corrosion resistance in sulphite digester liquor. In some media, like strongly oxidising acids, molybdenum may impair the corrosion resistance, and should therefore be avoided in such applications. Nitrogen (N) increases the strength, the corrosion resistance and also improves the structural stability of stainless steels. In many cases, especially for duplex stainless steels, it also improves the weldability.

to modify the structure, the mechanical properties and the

Copper (Cu) is beneficial for the corrosion resistance in cer-

corrosion resistance.

tain acids. Titanium (Ti) and niobium (Nb) are used as carb-

Nickel (Ni) is added to alter the structure of the steel but may also improve the corrosion resistance if sufficient amounts are added. Nickel is an austenite stabiliser, which means that an addition of nickel will alter the structure from ferritic to auste-

ide formers, which means that carbon is preferentally bound to these elements, thus reducing the risk for precipitation of deleterious chromium carbides in the grain boundaries, and hence decreasing the risk of intergranular corrosion.

nitic. In an alloy with 18% chromium about 10% nickel is

Four main types of structures exist in stainless steels; ferritic,

required to alter the structure to almost purely austenitic.

martensitic, austenitic and duplex (austenitic-ferritic).

I: 26


Austenitic stainless steels and Duplex stainless steels

tenite. These steels combine important properties from both ferritic and austenitic stainless steels. They show good stress

The austenitic family of stainless steels covers a broad inter-

corrosion resistance and also good ductility and weldability.

val of alloying elements, from standard 18-9 to super austeni-

All modern duplex stainless steels have a low carbon content.

tics with up to 7 % molybdenum and matching contents of

Duplex grades with PRE-number (PRE = Pitting Resistance

chromium and nickel. The super austenitics are often also

Equivalent = % Cr + 3.3% Mo + 16% N) greater than 40 are

alloyed with nitrogen. Their corrosion resistance is therefore

called super duplex. These steels possess very good corrosion

adapted to a great variety of corrosive environments. The

properties, especially in chloride containing environments.

super austenitics are most often designed to resist pitting and crevice corrosion in chloride containing environments, e.g.

The duplex structure gives high mechanical strength, approx-

sea water. They also have good resistance to stress corrosion

imately twice that of austenitics, combined with low thermal

cracking, in solutions containing hydrogen sulphide and in

expansion, close to that of carbon steel. The low Ni-content is

alkaline solutions.

cost saving and high mechanical strength means lighter construction, which gives cost advantages.

The austenitic steels have good ductility, at both low and high temperatures. Their weldability is good. The austenitic steels

The upper service temperature of duplex stainless steels is

are readily welded with all normally used techniques. High

around 300°C due to the risk of embrittlement and formation

alloy steels can be welded with over-alloyed filler metals,

of precipitates. The weldability of duplex stainless steels is

thus matching the corrosion resistance of the base metal.

good. Welding of duplex stainless steels with proper welding parameters and matching filler metals gives good corrosion

Duplex stainless steels are stainless steels with a microstruc-

and mechanical properties.

ture comprising typically 40-50% ferrite and the rest aus-

Figure 1. Microstructure of austenitic stainless steel.

Figure 2. Microstructure of duplex stainless steel. The dark areas are ferrite and the light areas are austenite.

I: 27


6.

Manufacturing programme

The most common steel grades manufactured by Sandvik

Sanicro 28 is easy to bend and expand using the same

Steel as seamless tube products are listed on page I:43-44.

methods as standard austenitic steels. Annealing is not norm-

Wet corrosive and high-temperature service alloys and hollow

ally necessary after cold bending. Machining is easy but re-

bar materials are shown. The corresponding corresponding names in the cor-

quires an adjustment of cutting data compared with AISI 316L.

rosion table and equivalent standards are shown together with mechanical properties.

The excellent corrosion properties of Sanicro 28 enable it to be used in the most diverse environments. Sanicro 28 is

Special stainless steel grades Special stainless steel grades have been developed to meet demands for higher corrosion resistance, favourable physical and mechanical properties and good structural stability and weldability. Descriptions of some special steel grades are given below. 904L/2RK65

widely used in the manufacturing of phosphoric acid by the "wet" method. It is suitable for piping and heat exchangers handling sulphuric acid. Other applications are in the oil and gas industry industry,, nuclear nuclear power power plants, plants, sea water and and chloridechloridebearing cooling water and also in the fertilizer industry. SAF 2304

SAF 2304 is a low alloy duplex stainless steel. In acidic envir-

Steel grade 904L / 2RK65 is a high-alloy stainless steel with

onments SAF 2304 possesses good good corrosion resistance, and it

low carbon content. It is fully austenitic, and less sensitive to

has a pitting resistance comparable to that of AISI 316L. It has

precipitation of ferrite and sigma phase than conventional

very good resistance to stress corrosion cracking in chloride-

austenitic grades with high molybdenum content. The grade

bearing bearing environmen environments, ts, much better better than AISI 316L. 316L. SAF

is intended for use under severe corrosive conditions. It is

2304 is also characterised by good resistance to general cor-

standardised and approved for pressure vessel use in several

rosion and pitting.

countries.

SAF 2304 is a modern duplex stainless steel with the chem-

Although originally developed to resist corrosion in dilute

ical composition balanced in such a manner that reformation

sulphuric acid, 904L / 2RK65 2RK65 has been employed in a great

of austenite in the heat-affected zone adjacent to the weld

variety of applications for many years. It has;

takes place quickly. This will give welded joints good mech-

– Good resistanc resistancee to general corrosio corrosion, n,

anical and corrosion properties.

especially in dilute sulphuric acid. – Good resistance resistance to pitting and crevice crevice corrosion. corrosion. – Very good resistance to stress corrosion cracking. – Good resistance resistance to intergranula intergranularr corrosion. corrosion. SANICRO 28

The favourable physical properties combined with resistance to stress corrosion cracking and other forms of corrosion means that, that, in many applicatio applications ns SAF 2304 2304 is a superior superior alternative to stainless steels such as the austenitics austenitics 316L, 321 and 347, the ferritics AISI 430, 444 and the martensitics martensitics AISI AISI

Sanicro 28 is a multipurpose austenitic stainless extra low

410 and 420. SAF 2304 is used in chloride-bearing environ-

carbon content alloy. It is designed for use in highly corrosive

ments, such as heat exchangers exchangers in the process industry where where

environments. Sanicro 28 has very high corrosion resistance

stress corrosion cracking is a problem. The high strength

in strong acids and very good resistance to stress corrosion

makes it possible to use thinner sections in mechanical con-

cracking cracking and intergranu intergranular lar corrosion, corrosion, and also very very high

structions and piping systems.

resistance to pitting and crevice corrosion. Sanicro 28 possesses good weldability. Welding should be carried out without preheating and there will be no need for any subsequent heat treatment. The very low impurity content of Sanicro 28 minimises the risk of hot-cracking in the weld metal.

I: 28

SAF 2205

SAF 2205 is a duplex stainless steel with high resistance to stress corrosion cracking in chloride-bearing environments containing hydrogen sulphide. SAF 2205 is also characteris ed by high high resistance to general corrosion, pitting and crevice corrosion. In most media SAF 2205 possesses better resistance than steel of type AISI 316L and 317L.


SAF 2205 is a modern duplex stainless steel with the chem-

The high levels of molybdenum in particular but also of chro-

ical composition balanced in such a manner that reformation

mium and nitrogen endow 254 SMO with extremely good

of austenite in the heat-affected zone adjacent to the weld

resistance to pitting and crevice corrosion. The addition of cop-

takes place quickly. This will give welded joints good

per provides improved resistance in certain acids. Furthermore,

mechanical and corrosion properties.

due to it is relatively high nickel content in combination with the high level of chromium and molybdenum 254 SMO pos-

SAF 2205 is used in environments containing chlorides and

sesses good resistance to stress corrosion cracking.

hydrogen sulphide, e.g. in tubing and flowlines flowlines for the extrac-

The high nitrogen content of 254 SMO gives it a higher

tion of oil and and gas from sour sour wells, in refineries and in pro-

mechanical strength than other austenitic stainless steels. In

cess solutions containing chlorides. It is also suitable in heat

common common with the austeniti austeniticc stainless stainless steels, 254 SMO SMO is

exchangers where chloride-bearing water is used as cooling

characterised by high ductility and impact strength as well as

medium. The steel can be used in dilute sulphuric acid solu-

good weldability. A super alloyed welding consumable,

tions and solutions of organic acids.

designated designated Avesta Avesta P12, P12, is used for welding and the weld

SAF 2507

SAF 2507 is a high alloy super duplex stainless steel. It has excellent resistance to stress corrosion cracking and localised

metal thus produced has equally good corrosion resistance as the parent metal. 654 SMO

corrosion in chloride-bearing environments and good resist-

654 SMO is a high alloyed austenitic stainless steel which,

ance in environments containing hydrogen sulphide.

due to its high nitrogen nitrogen and molybdenum molybdenum content, content, possesses

SAF 2507 is also characterised by high resistance to corrosion in both inorganic and organic acid.

very high resistance to pitting and crevice corrosion. The steel grade was developed by Avesta Avesta Sheffield AB for use in halide containing environments more aggressive than those which

This steel grade is a so called super super duplex grade, i.e. a steel

can be handled by 254 SMO, SMO, e.g. sea water at high temper-

with a PRE-number greater than 40 (PRE = Pitting Resistance

atures and scrubber solutions. 654 SMO also shows good

Equivalent = % Cr + 3.3% Mo + 16% N). The ferrite content

resistance to general corrosion in acids and especially halide-

is generally between 35 and 50 %. SAF 2507 is a modern

containing acids. The addition of copper improves the corro-

duplex stainless steel with the chemical composition balanced

sion resistance in reducing acids. The high levels of nickel

in such a manner that reformation of austenite in the heat-

and molybdenum contribute to the high resistance to stress

affected zone adjacent to the weld takes place quickly. This

corrosion cracking.

will give welded joints good corrosion properties and a toughness roughly equal to that of the parent metal. SAF 2507 is used in chloride-bearing environments and environments containing hydrogen hydrogen sulphide, e.g. in process systems in the oil and gas industry and in heat exchangers where the cooling medium is chloride-bearing or chlorinated water. It is also used in the handling of organic and inorganic acids.

654 SMO possesses high yield and tensile strengths. The ductility and impact toughness are also very high. 654 SMO is welded with a nickel-base filler material over-alloyed in molybdenum, designated Avesta Avesta P16. The weldability of the steel is good but the welding requires special care. Thorough post weld cleaning is very important in order to obtain optimum corrosion resistance.

The higher allowable yield stress levels permitted in e.g. ASTM B31.3 means that substantial reduction in wall thick-

Nickel base alloys

ness is possible for all duplex stainless steels piping systems,

Nickel base alloys can in general be divided into five different

resulting in major savings in weight and overall costs.

groups according to their major alloying element. The first group group is the unalloyed unalloyed Nickel, Nickel, the Alloy Alloy 200-series, 200-series, which is

254 SMO

suitable for use in a lkaline environments. The second group is

254 SMO is an austenitic stainless steel which, due to its high

the Nickel-Copper-alloys, Nickel-Copper-alloys, the Alloy 400-series. 400-series. These alloys

molybdenum content, possesses very high resistance to pitting

are suitable for seawater service and are also used in sulphuric

and crevice corrosion. The steel grade was developed by

acid. The Nickel-Chromium group of alloys is the 600-series.

Avesta Sheffield AB for use in halide-containing environ-

These are used in highly oxidising environments, environments, like nitric

ments such as seawater. 254 SMO also shows good resistance

acid, and also for high temperature service. If the the 600-series

to general corrosion and, especially in acid containing halides,

alloys are also alloyed with molybdenum they become suita-

this steel grade is superior to conventional stainless steels.

ble to use in weak reducing environments. The next group

I: 29


Table 1. Examples of Alloy compositions in the different series S eri es

Alloy example

U NS des ignation

C o m p o s i t i on Ni

Cr

Mo

Fe

Cu

Other

2 00

A l l oy 2 0 0

N02 200

9 9.2

–

–

–

–

–

4 00

A l l oy 4 0 0

N04 400

bal .

–

–

1.25

3 1.5

–

6 00

A l l oy 6 0 0

N06 600

bal .

16

–

8.0

–

–

A l l oy 6 2 5

N06 625

62

2 1 .5

9.0

<5.0

–

4.0 Nb

A l l oy 8 0 0

N08 800

3 2.5

21

–

44

–

0.4 Ti

A l l oy 8 2 5

N08 825

42

2 1 .5

3.0

29

2 .0

1.0 Ti

A l l oy B

N10 00 1

bal .

< 1 .0

28

5.0

–

–

8 00 1 000

The borderline between the different groups is rather vague and new combinations of alloying elements are continuously added to produce specific properties. If the different nickel base alloys are used in their intended environment they usually outperform the stainless steel alternative. However, However, the cost for Nickel base alloys is significantly higher compared to stainless steel alternatives.

comprises nickel alloyed with chromium and iron, the 800-

many chemical solutions, such as nitric and hydrochloric hydrochloric acid

series. These alloys are used for high temperature service.

environments environments at high temperatur, and in varying strong acidic

This group could also be alloyed with molybdenum and then

and strong alkaline environments. Zirconium is also very

be used in phosphoric acid. Finally there are the Nickel-

resistant to corrosive attack in most organic and mineral ac ids

Molybdenum Molybdenum alloy alloys, s, the 1000-serie 1000-series, s, which are are suitable suitable for

and some molten salts. Zirconium has excellent oxidation

strong reducing environments like hydrochloric acid.

resistance resistance up to about about 400°C 400°C in air, air, steam, carbon dioxide, dioxide, nitrogen and oxygen. In media containing fluorides or fluor-

Titanium Titanium can be used in many cases where stainless steels are not sufficiently corrosion resistant.Unalloyed titanium shows a very good good resistance to damp chlorine gas, chlorides and chloride containing compounds, such as chlorine chlorine dioxide. In

ine zirconiu zirconium, m, like titaniu titanium, m, has poor poor resistanc resistancee compared compared with stainless steel but its resistance to bromide and chloride is very good. A comparision of test results from Huey testing (the samples are boiled for 5 periods of 48 hours each in 65% nitric acid) is shown in figure 1.

dry chlorine chlorine gas, with less than 0.4 0.4 % water, water, titanium titanium is how-

Zirconium is used in equipment such as heat exchangers,

ever severely attacked. Titanium shows a good resistance to

reboil reboilers, ers, column columns, s, reactor reactors, s, evapo evaporato rators, rs, pumps, pumps, and piping piping

nitric acid, and at very very high temperatures in dilute solutions, solutions,

systems for example in the production of urea and acetic acid,

titanium titanium is superior superior to stainless steels. In certain media, like

formic acids and other organic acids and compounds.

those containing fluorides or red fuming nitric acid, titanium has a poor resistance compared to stainless steels.

Detailed corrosion data on zirconium in various environments are provided on request.

Titanium is used in many types of process equipment e.g. as tubing tubing in heat exchangers, exchangers, coolers, coolers, condensers condensers and pipework: pipework:

Corrosion rate [mm/year]

0,20

– On oil platfor platforms, ms, in refiner refineries ies,, chemic chemical al industr industries, ies, process process

0,18

industries and other industries using sea water or chlorin-

0,16

ated sea water as coolant.

0,14

– In refineries refineries and petrochemic petrochemical al plants where the process process

0,12

envir environm onment ent contain containss chlo chlorid rides, es, sulphi sulphides des,, organ organics, ics, or-

0,10

ganic acids, acids, nitric acid or wet chlorine. chlorine.

0,08

– Titanium is also used in pulp pulp and paper industries as tubing for chloride containing bleaching agents.

0,06 0,04 0,02

Zirconium Zirconium can be used in a variety of chemical processing applications. Unalloyed zirconium has good resistance to

I: 30

0,00

Z r 70 2 AS TM TM UNS S31050 TP310, Modified (low carbon)

Figure 1. Huey test.

UNS S31603

UNS S32304 Material


7.

Applications for stainless steels

Chemical industry

SULPHURIC ACID

Sulphuric acid is manufactured by catalytic oxidation of SO2

INTRODUCTION

to SO3 which is combined with water to form H2SO4. The raw material is sulphur or pyrites, which is burnt at 1100°C to

The introduction of stainless steel construction materials for process equipment has made a major contribution to the

form SO2 which is then further processed to acid. In the roasting of pyrites at high temperature, overlay welded car-

development of modern chemical industries. Established standard grades are used extensively, but there are increasing

bon steel or composite tubes in 10RE51/4L7 may be used.

requirements for further improvements in corrosion resist-

When the acid is cooled down, stainless steels are normal

ance to extend service life and reduce costly down time.

materials of construction. Sulphuric acid is also used in other

This has promoted the development of several enhanced

processes, such as phosphoric acid, ammonium sulphate,

alloys. Some are multi-purpose grades with better general

titanium dioxide and rayon manufacturing. Phosphoric acid is

corrosion resistance, whereas other were originally designed

described below.

to meet specific process applications and are more or less Ma te ri als of constr ucti on

single purpose grades.

The corrosion of stainless steels in sulphuric acid is very

The drive to increase effiency, often by utilising higher tem-

dependent on the concentration of the acid. Traditionally the

peratures and pressures, which can create more aggressive

material of construction was high Si iron, but stainless steels

conditions, means that new material solutions will continually

are increasingly used. In table 1 an overview of materials

be required.

selection is shown. For detailed information, see the corrosion tables and isocorrosion diagrams. Impurities may increase or

Stainless steels are used in e.g. heat exchangers, piping sys-

decrease the corrosivity of sulphuric acid. In general, most

tems, an a variety of vessels such as holding tanks, reaction

species added will decrease the corrosivity as long as they

vessels, columns, etc.

contain no halide ions. On the other hand, contaminations of

A review of some of the most common corrosive process

chlorides and fluorides in sulphuric acid increase corrosivity

applications follows.

and if the levels are high, special stainless steels such as Sanicro 28 must be used.

Table 1. Overview of materials choice for various concentration ranges of sulphuric acid. For detailed information, see corrosion tables and isocorrosion diagrams. Concentration range H2 SO 4 , % < 10

Temperature, °C

Materials selection

< 40

Standard stainless steels, such as Sandvik 3R12, 3R60

< 20

< 80

High alloyed stainless steel, such as SAF 2205, SAF 2507, Sandvik 2RK65, Sanicro 28

20 - 70

< 50

Cu-alloyed stainless steel, such as Sanicro 28, Sandvik 2RK65

20 - 70

> 50

Nickel base alloy UNS N10665 (alloy B) or Zirconium

70 - 96

< 50

High alloyed stainless steel, such as SAF 2205, SAF 2507, Sanicro 28

70 - 96

> 50

Tantalum or Si-iron

98

>60

Sandvik SX*

* Sandvik SX is supplied by Edmeston AB

Table 2. Impurities in 70% H 3PO 4 in weight-%. Impurity

SO 3

F-

Cl -

Si O 2

Al2O3

Fe 2 O 3

MgO

Concentration, %

1-4

0.1-1.5

0.002-0.05

0.01-0.7

0.2-3.0

0.1-2.5

0.1-1.5

I: 31


PHOSPHORIC ACID

Phosphoric acid is extracted from rock phosphate. The most

Table 4. Allowable limits on combined chloride and

wet method, where the rock is dissolved in sulphuric acid,

fluoride content for various alloys in a solution of 70% H 3PO 4 , 4% H 2SO 4 and 0.45% Fe3+ at 100°C. The limits are based on a max corrosion rate of

which yields phosphoric acid and calcium sulphate together

0.3 mm/year.

common method of manufacturing phosphoric acid is by the

with some impurities. The impurity level has a crucial effect

Alloy

Maximum F- %

Maximum Cl- %

on the corrosivity of the acid and influences materials selec-

Alloy 825

0.3

0.015

tion. The phosphoric acid is concentrated to the desired level

Sandvik 2RK65

0.2

0.04

by evaporation.

Sandvik SAF 2507

0.6

0.06

Sandvik Sanicro 28

0.8

0.07

Systems for concentrating phosphoric acid usually include heat exchangers in graphite or stainless steel, or heating ele-

steels and to nickel base alloys. It has been found that the cor-

ments of the prayon type. The prayon type has the advantage Impurity leveles in the acid vary with the origin of the rock

rosivity declines with increasing amount of metallic ions, such as Mg2+, added to the process solution. Addition of 0.25-0.50% Mg2+ decreases the corrosion rate for Sanicro 28

phosphate. Normal concentrations of impurities in concen-

from nearly 3 mm/year down to 0.1 mm/year.

that individual elements (tubes) can be replaced easily.

trated acid are shown in table 2. The impurity level may be higher in phosphoric acid of lower concentration. Table 3 shows the relative corrosivity of acid produced from various sources.

different phosphate sources. Corrosivity

Phosphate

Low

South Africa (Phalaborwa ) Nauru Senegal ( Taiba ) Florida ( Tampa, Pebble ) Brazil ( Araxa ) Nor th Carolina Kola Morocco ( Khourigba, Youssoufia ) Sahara ( Bu Craa ) Tunisia ( Gafsa ) Togo Syria Jordan Israel Mexico

High (high chloride phosphates)

Nitric acid is produced by an ammonia oxidation process. Liquid ammonia is evaporated, superheated, then mixed with compressed air and passed to a catalytic converter where

Table 3. Corrosivity of phosphoric acid obtained from

Medium

NITRIC ACID

ammonia oxidation takes place at 850-950°C. The resulting nitrous oxide is cooled and converted to nitrogen dioxide in an oxidation tower, and finally the gas is absorbed by water in a column to form 57-60% nitric acid. The plants include several heat exchangers where the environment is highly oxidising. The severest tube conditions are normally found in the tail gas preheaters, boiler feed water heaters and cooler/condensors where local condensing and reboiling of acid may occur. Ma te ri als of constr ucti on

In oxidising environment a high chromium content is favourable. Molybdenum has been found to be detrimental to the corrosion resistance. Therefore low molybdenum or molybdenum free materials are normally used as construction

Mate ri al s of constr ucti on

Concentration of phosphoric acid from 28% P 2O5 to 52% P2O5 (70% H3PO4) is the normal production route. In these

materials. The standard material of construction is the austenitic AISI 304L, but in certain critical areas special alloys have to be used.

units more or less aggressive conditions appear. As stated earlier, the corrosivity is very dependent on the impurity

Tail gas preheaters

level. At low or zero concentrations of impurities standard

Tail gas preheaters are normally tubular heat exchangers,

grades such as AISI 316L or 317L may be used, whereas at

where cold nitric acid tail gas from the absorption tower is

higher concentrations special alloys such as Sandvik 2RK65,

heated, and boiling occurs when the droplets entrained in the

duplex stainless steels or Sanicro 28 have to be used. Table 4

tail gas hit the hot tube wall and evaporate. The conditions are

gives limits on fluoride and chloride contents in a typical

approximately 35% HNO3 at 120-140°C. Some materials of

(“Florida type“) phosphoric acid solution.

construction are:

Superphosphoric acidis manufactured by concentrating 52-54% P2O5 to 70% P2O5 at temperatures up to 200°C. This acid is very aggressive to both highly alloyed stainless

I: 32

• AISI 304L • Sandvik 2RE10 • AISI 329 • Sandvik SAF 2304

(less common) (less common)


Normally it is sufficient to use standard austenitic grades, but in some plants problems with corrosion occur. In these cases Sandvik 2RE10 is a good choice, and this alloy is therefore

AISI 321 W.-Nr. 1.4541

AT = Solution annealed S = Sensitisation 650 C/1h (1200 F/1h)

AISI 304L W.-Nr. 1.4306

AT S

Sandvik 3R12

AT S

AISI 329

AT S/ 5 min

Sandvik

AT S

°

°

recommended for new constructions with no past experience. Cooler/condensors

The cooler/condensors are normally tubular heat exchangers with the process gas on the tube side. Corrosion is common at the inlet where the first condensate is formed. If reboiling of the condensate occurs, the conditions become very severe. An

7100

0.1 (4)

0.2 (8)

0.3 (12)

illustration of the hot dew point corrosion is shown in figure

0.4 0.5 0.6 0.7 0.8 0.9 1.0 (16) (20) (24) (28) (32) (36) (40) Corrosion rate (mean of 5x48h), mm/year (mpy)

1. In this instance the gas is cooled from the relatively high

Figure 2. Statistical evaluation of Huey-test results.

inlet temperature of 210°C down to 50°C.

Arrows denote accelerated attack.

Since the corrosive conditions at the tube inlet are so high,

ORGANIC ACIDS

Organic acids belong to the most important group of chem-

Sandvik 2RE10 has to be used.

icals in the modern chemical industry. In the petrochemical If cooling water contains chlorides, the use of the duplex

industry these chemicals are common. This acid group in-

stainless steel Sandvik SAF 2304 or grade Sandvik Sanicro

cludes a large number with differing properties. The corros-

28, should be condsidered. The experience with these mater-

ivity of different organic compounds is extremely varied.

ials is however limited. Organic acids have an alkyl group coupled to the acid group (-COOH). As a general rule, the corrosivity of the acid in1

2 7101b

creases when the alkyl group decreases in size; consequently most of the problems with corrosion are related to products or

Process gas

intermediates containing Formic Acid (HCOOH) or Acetic Tube sheet

Acid (CH3COOH). Organic acids are generally reducing, but impurities such as chlorides, traces of catalysts, or air, may increase the oxidising power of the process solution.

Figure 1. Illustration of hot dew point corrosion in nitric acid cooler/condensors.

Ma te ri als of constr ucti on

1 = First condensate formed 120-130°C

There are a wide range of materials used for equipment hand-

2 = Reboiling - corrosion increases with increasing temperature.

ling organic acids, ranging from the Austenitic 304L to Duplex Stainless Steels, Nickel base alloys and Zirconium. Traditionally, alloys like 304L, 316L and Alloy 20 (UNS

Boiler feed water heaters

N08020) have been used but today high alloyed materials are

Corrosion in boiler feed water heaters can occur at the outlet

increasingly used to counter the possible shifting in redox

end. If a condensate is formed there is a risk of reboiling and

potential over time, which can result in these acids becoming

therefore a risk for corrosion on AISI 304L. Normally the

more corrosive.

design is made to avoid condensation, but if 304L fails Sandvik 2RE10 should be used.

Acet ic acid

Generally, AISI 304L can be used for Acetic acid applications Accept an ce te stin g

up to 60°C regardless of concentration, whereas at higher

Materials for nitric acid service are normally evaluated by a

temperatures up to the atmospheric boiling point, AISI 316L

Huey test ( ASTM A262 Practice C, 5x48 h in boiling 65%

may be applied. The isocorrosion diagram is shown in the

nitric acid ). Figure 3 shows values from Huey tests of various

corrosion tables section. In Acetic aci d above the atmospheric

alloys used in nitric acid plants. A Huey test after a sens-

boiling point there is a risk of HCl formation if the solution is

itization heat treatment is also shown. Sensitization may

contaminated with chlorides. Higher alloyed materials such

occur during welding when tubes are installed.

as Sanicro 28 or SAF 2507 should be considered in these circumstances. Alloy C-276 ( UNS N10276 ) has been used in some cases with extremely severe conditions.

I: 33


Contamination by formic acid, catalysts or chlorides can

Formic acid

cause severe pitting of 316L, and therefore upgrading to a

Formic acid is relatively corrosive 304L may be used at ambi-

higher alloyed material is necessary. Anhydrous Acetic acid

ent temperature for e.g. storage tanks, whereas at higher tem-

and traces of Acetic anhydride will also drastically increase

peratures 316L is preferred, but only below the 10% concen-

the corrosion rate. Alloy selection depends on the amount and

tration level. At higher concentrations, materials like Sanicro

type of contaminants in some cases with reducing conditions.

28 and SAF 2507 are preferred materials. The isocorrosion

Alloy B-2 has been applied in these aggressive conditions.

diagram is shown in the corrosion tables. Figure 5 shows cor-

More exotic materials such as Zirconium are also applicable.

rosion rates of various alloys in Formic acid with chlorides.

Figure 4 shows the corrosion rate of various alloys in Acetic acid with chlorides. Figure 4 shows the corrosion rate of

Corrosion, mm/year 1.2

6759

various alloys in Acetic acid with Acetic anhydride and chlorides. Clearly, 316L is unsuitable in contaminated acid. Where

1.0

Acetic anhydride is present even SAF 2205 has a too high corrosion rate. Here either SAF 2507 or a Nickel base alloy like alloy 625 ( UNS N06625 ) has to be used.

0.8

0.6

0.4

Corr. rate mm/year

6967

0.15

0.2

>1 mm/ year

0 C-276

0.10

C-22

C-4

SAF 2507

A 625

SAF 2205

Figure 5. Corrosion rates of various alloys in boiling 40% Formic acid with 2000 ppm chlorides.

0.05

Teraphtalic a cid

Teraphtalic acid is an organic acid which is an intermediate for polyester fibre manufacturing. AISI 317L has been a

0 AISI 316L

SAF 2205

Sanicro 28

SAF 2507

254 SMO

standard material of construction, but in some cases with limited lifetime due to corrosion. Higher alloyed materials

Figure 3. Corrosion rates of various alloys in 80%

such as the duplex SAF 2205 or SAF 2507 are suitable altern-

Acetic acid with 2000 ppm chlorides a t 90°C.

ative materials. In table 5 results from in plant testing in a a cid plant is shown. Whereas AISI 317L had corrosion rat es which

Corr. rate mm/year

limited the lifetime of the equipment, SAF 2205 and SAF

0.05

2507 showed very good resistance. >0.1 mm/ year

Table 5. Various alloys tested in a teraphtalic acid plant.

6969

0 SAF 2205

SAF 2507

A 625

C–4

C–22

C–276

Figure 4. Corrosion rates of various alloys in a boiling solution of 99.8% Acetic acid, 0.1% Acetic anhydride and 200 ppm chlorides

I: 34

Alloy

75% Acetic acid T ra ce s of B ro mi ne , C u, Mn , T =1 75 °C mm/year

96% Acetic acid T ra ce s of B ro mi ne , C u, Mn , T =1 50 °C mm/year

AISI 317L

0.44

0.67

SAF 2205

0.012

0.06

SAF 2507

0.004

0.011


Urea production

corrosivity of the ammonium carbamate and to maintain passivity of the construction materials. Today, there are a few big

INTRODUCTION

Urea is a nitrogen based chemical which is very common for use as a synthetic fertiliser in agriculture. It has the highest nitrogen content (46%) of commercial synthetic fertilisers. Urea is also used as raw material for e.g. melamine production.

licensers on the market with slightly different designs. The most common are Stamicarbon, Snamprogetti and Toyo but other actors such as Urea Casale and UTI are also very active, especially for revamping plants of older design. A flow sheet of a urea plant of Stamicarbon design is shown

Urea in itself is not very corrosive, but during manufacturing of urea the process fluid becomes very aggressive in the high temperature section. Special stainless steels have been developed for use under these conditions, and the process has to be very carefully controlled, especially regarding the oxygen content in the process fluid, in order to maintain passivity of the materials.

in figure 6. In the reactor the urea and carbamate mixture is formed. The solution is fed to a stripper, which is a falling film heat exchanger where the solution is fed in the direction of gravity, and a stripping gas (CO2) is fed in the other direction. The carbamate is here separated from the urea, and the carbamate is fed to the high pressure carbamate condensor and recycled to the reactor, whereas the urea is depressurised downstream and finally solidified to urea prills, usually in a prilling tower. During the depressurisation any remaining car-

THE UREA PROCESS

bamate is condensed in the low pressure carbamate con-

Urea is produced by mixing ammonia (NH3) and carbon dioxide (CO2) at high pressure and temperature; typical conditions are temperatures of 200 °C at 200 atm pressure. Under

densor, followed by compressing and recycling to the reactor. MATERIALS OF CONSTRUCTION

these conditions ammonia and carbon dioxide react to form

In the high pressure part of the urea processes special stain-

ammonium carbamate, which is very corrosive. The ammoni-

less steels have to be used. In table 1 the most common alloys

um carbamate then partly reacts to form urea. In modern re-

used today are listed. Table 2 lists the most common materials

cycle processes the remaining carbamate is stripped from the

of construction in the various parts of the high pressure sec-

process fluid downstream from the reactor and recycled to the

tion of urea plants.

reactor. Oxygen is added to the process fluid to control the

Tubes

Scrubber Plates

CW

2RE69, 3R60 U.G.

HP Carbamate Condenser

3R60 U.G., 2RE69, SAF 2205, SAFUREX™

Steam Reactor

LP Carbamate Condenser

Water

6.6 kg/s NH3 H.P. Piping 3R60 U.G., 3R69, 2RE69 SAF 2205, SAFUREX™

Steam Condensates Tubes 2RE69, SAFUREX™

Stripper

e t a m a b r a C a e r U

CO2 8.74 kg/s Urea Solution

Prilling Tower Air 11.57 kg/s Urea Prills Urea Solution Storage Evaporator

Figure 6. Flowsheet of Stamicarbon urea process. Materials choice for critical parts are indicated.

I: 35


Stripper

The stripper is a tubular heat exchanger with a carbon steel shell. The tube plates and vessel heads are overlay welded with stainless steel and the tubes are of seamless stainless type. The overlay is usually of 2RE69-type and the tubes are made of 2RE69 (Stamicarbon process) or bimetallic tubes with an outer layer of 2RE69 and an inner liner of Zr702, mechanically bonded together ( Snamprogetti process ). Alternative materials of construction are SAFUREX™ (Stamicarbon) or Titanium (Snamprogetti). Titanium is however hardly ever used for new Snamprogetti plants, instead the more resistant bimetallic tubes are used. The corrosivity of the process fluid is very high in the stripper, and corrosion

Figure 7. Solidified urea prills.

problems occur at the top part of the stripper if the amount of

Table 6. Common alloys used in urea plants Sandvik designation

UNS Number

Remarks

Sandvik 3R60 U.G.

S31603

< 0.6% ferrite

Sandvik 2RE69

S31050

< 0.6% ferrite

Sandvik SAF 2205

S31803

40-60% ferrite

Sandvik SAFUREX™-

S32906

40-60% ferrite

Bimetal lic 2 RE69/Zr 702

S31050/R60702

-

oxygen added is too low.

Carbamate condensor

The carbamate condensor is a tubular heat exchanger with a carbon steel shell. The tube plates and vessel heads are overlay welded with 2RE69 and the tubes can be either 2RE69 or 3R60 U.G. Corrosion problems that occur are usually from the cooling water side if chlorides are present. Even chloride

Table 7. Materials selection in the high pressure part of

contents as low as 5 ppm may cause stress corrosion cracking

urea plants

of the alloys 2RE69 and 3R60 U.G. New materials of con-

Section

Product form

Alloy

struction for the Stamicarbon plants to solve stress corrosion

Reactor

Plate

3R60 U.G.

cracking problems are SAF2205 and SAFUREX™. These

2RE69

alloys have a duplex (austenitic-ferritic) microstructure and

SAFUREX™ ( Stamicarbon )

have shown good resistance to both the water side and the

2RE69 ( Stamicarbon )

process side conditions.

Stripper

Seamless tubes

SAFUREX™ ( Stamicarbon ) Bimetallic 2RE69/Zr702 (Snamprogetti ) Carbamate

Seamless tubes

Condensor

3R60 U.G.

High pressure piping connecting the vessels is usually made

2RE69

in 3R60 U.G. or 2RE69. Materials such as the duplex grades

SAF2205 ( Stamicarbon )

SAF 2205 and SAFUREX™ are excellent alternatives due to

SAFUREX™ ( Stamicarbon ) H.P. Piping

Seamless pipes

High pressure piping

3R60 U.G.

their high mechanical strength.

3R69 2RE69 SAF2205 ( Stamicarbon ) SAFUREX™ ( Stamicarbon )

ACCEPTANCE TESTING

Materials for urea service have to be corrosion tested in order to ensure that the materials are of good quality. Usually the

Reactor

intergranular corrosion resistance has to be determined and

The reactor is a vessel made of carbon steel lined on the in-

the most common test method is the Huey test (ASTM A262

side with stainless steel. The reactor also contain trays de-

Practice C, 5x48 h in boiling 65% Nitric Acid), but for the

signed to make the reaction more effective. 3R60 U.G. is fre-

duplex stainles steels the Streic her test (ASTM A262 Practice

quently used in the reactor, but sometimes problems with cor-

B, 120 h in boiling ferric sulphate-sulphuric acid solution) has

rosion occur, especially in the lower part of the vessel.

been adopted. An illustration of intergranular corrosion

Relining is then often made with 2RE69 which offer better

testing is shown in figure 8.

long term corrosion resistance. Nowadays 2RE69 is frequently specified also for new plants. An alternative to 2RE69

Table 8 lists the acceptance tests for various alloys used in

for the Stamicarbon plants is Sandvik SAFUREX™.

urea service.

I: 36


Table 8. Acceptance tests of materials for use in urea

and gas extracting units. It will include presentations of cor-

service.

rosion in process fluids and in sea water and materials selec-

Alloy

Test

Max corrosion rate mm/year

Max selective attack Long. Trans.

Sandvik3R60 U.G.

Huey

0.60

200

70

Sandvik 3R69

Huey

0.60

200

70

Sandvik 2RE69

Huey

0.12

70

70

Sandvik SAF 2205

Streicher

1.78

100

100

Sandvik SAFUREX™ Streicher

0.78

70

70

tion for the different systems involved.

CORROSION

Process fluids

Although hydrocarbons are not themselves corrosive, the process often contains H2S and CO2 in varying amounts. A well that does not contain H2S, or at least does not have a partial pressure of hydrogen sulphide above 0.05psi, is often referred to as sweet, irrespective of the CO2 content. If the partial pressure of hydrogen sulphide exceeds 0.05psi the well conditions are referred to as sour. The conditions vary from almost totally free from H2S in parts of the North Sea to very sour in e.g. some of the Middle East fields. The risk of cracking due to hydrogen sulphide is often the main factor to consider when selecting materials for exposure to process fluids. Sulphides attached to the metal surface catalyse the absorption of hydrogen atoms by the metallic material. Atomic hydrogen diffuses readily into the steel to regions where some discontinuity, e.g. a non-metallic inclusion, is situated. Such an inclusion is not atomically bonded to the steel so there can be room for two hydrogen atoms and the

Figure 8. Intergranular corrosion.

possibility to create a hydrogen molecule, H2, is created. The hydrogen molecule has a very large volume compared to that of two hydrogen atoms, which causes an extremely high pressure between the inclusion and the metallic material. This pressure can be much higher than the strength of the steel and

Oil & Gas industry Corrosion problems and materials selection INTRODUCTION

There are basically two corrosive environments within the oil and gas industry; Sea Water and Process Fluids. Whereas sea

is therefore capable of causing rupture of the material. All of the mechanisms involved in hydrogen embrittlement due to the presence of H2S are however not yet fully understood. Carbon steels suffer from uniform corrosion (when exposed to fluids containing carbon dioxide). This would not be a

elements, irrespective of field development; process fluids

problem for stainless steel grades but because CO2 reacts with liquid water in the production stream to form carbonic

vary a lot from well to well. The hydrocarbons themselves are

acid, the pH value can be significantly lowered by its pres-

not corrosive, but the process fluids can contain CO2, H2S, which together with chlorides make the environment aggres-

ence, which in turn makes the environment more corrosive

sive from a corrosion point of view.

with iron in the alloy to form iron carbonate, FeCO3.

water can be said to contain more or less the same corrosive

Traditionally carbon steels have been used to a great extent in

also to stainless steel grades. The carbonic acid can then react

Sea water

oil and gas production units. Today more than 95% of plants

When studying the corrosivity of sea water, the main en-

are using carbon steels for their systems. However the use of

vironmental factors are: chloride content, pH, temperature,

corrosion resistant alloys (CRAS), from 13Cr and upwardsis

oxidizing strength (oxygen and residual chlorine contents)

increasing significantly as the trend is directed towards

and other factors including fouling, stagnant/flowing solution

deeper wells with elevated H2S contents and higher temperatures, creating more aggressive environments. This survey

and galvanic action. The most common corrosion phenomena

will discuss the different parts of the systems present in oil

crevice corrosion and, at temperatures above 50-60°C, stress

that can (and do) occur in this environment are pitting and

I: 37


corrosion cracking. All types of corrosion mentioned here are

Flowlines

localised attacks. General attacks do not need to be con-

The exctracted process fluids are transported via the wellhead

sidered for stainless steels since the corrosion rate is very low

to flowlines, which connect the well with the process equip-

in sea water.

ment. Flowlines may be several kilometers long e.g.from a

Within the oil and gas industry, materials can be exposed to

satellite well to the actual processing site. The flowlines are

sea water in three ways. Subsea flowlines are exposed to

exposed to both the process fluids (inside) and (if subsea) sea

relatively cold and oxygen poor sea water at certain depths.

water (outside). Stainless steel grades are increasingly used

These materials are often covered with biological species

for these lines. One of the most widely used CRAs has been

such as barnacles and mussels, creating somewhat more se-

duplex 22Cr (SAF 2205); a grade that has good resistance to

vere conditions. Secondly, the sea water systems on a platform are exposed to sea water internally. These systems are

CO2 and to H2S induced attacks and also, to a certain degree, to sea water. Super duplex 25Cr /(SAF 2507) has also been

often chlorinated to prevent the build-up of a biological layer

gaining market shares thanks to the higher strength which can

on the surface. The chlorination elevates the corrosion poten-

reduce the wall thickness, thus reducing the tonnage.

tial dramatically thereby putting high demands on the materials used. The third type of exposure is by the splashing of sea

Recently, weldable martensitic 13Cr steels have reached the

create a risk for external chloride induced stress corrosion

market. These also seem to be a good solution for CO2 containing fluids with low H 2S levels.

cracking if the materials used are too low alloyed for the ser-

For very severe process fluids higher alloyed stainless steels

vice conditions.

or nickel base alloys can be chosen.

water on to the platform and its topside systems. This might

For short flowlines, between e.g. wellhead and floating platform, sometimes flexible pipes are chosen, in order to accompodate the motions created by the sea. The flexible flowlines consist of an inner CRA liner and plastics armoured with carbon steel. The CRAs used vary from grade 316L up to highly alloyed nickel base alloys.

Umbilicals

An umbilical is operating subsea as a connection between the platform’s control station and the wells on the seabed. The umbilical normally contains electrical and hydraulic lines for Figure 9. North Sea oil platform.

well control as well as lines for injection of methanol and other chemicals, typically to prevent coagulation of the oil. A common cross section configuration is to have the larger met-

M A T E R I A L AT O I L A N D G A S E X T R A C T I N G U N I T S

hanol injection line in the center of the umbilical with the

Tubing and Casing

hydraulic and the electrical lines surrounding it. Pressures up

These tubes, production tubing and outer casings, are often

to 10 000 psi (700 bar) are typical for the hydraulic and chem-

referred to as Oil Country Tubular Goods (OCTG). The size

ical injection lines.

of the casing are in the range from 4 1/2" to 13 3/8" and the tubing is in the 2 7/8" to 4 1/2", and positioned at the actual well site. The production tubing will be the first material to be exposed to (often) relatively hot process fluids at high pres-

The part of the umbilical that is lying on the seabed is called the static part since it is only to a minor extent influenced by the motions of the sea water.

sure. Traditionally carbon steels have been used for this appli-

The dynamic part of the umbilical is the one hanging from the

cation but recently martensitic 13Cr and duplex SAF 22Cr

platform down to the seabed. This part is more influenced by

grades have been used more frequently. For very severe con-

the sea water motions.

ditions, with rhigher H2S levels, nickel base alloys, such as Alloy 825 /Sanicro 28 and Hastelloy C-276, are used. The

When a floating production unit is used the movements of the

tubes used for this application are often cold worked to spe-

umbilical are further increased and this puts higher demands

cific minimum strength levels. The tubes are connected by

on the materials used with respect to corrosion and fatigue

couplings and therefore do not have to be weldable.

properties. The materials used for this type of service include

I: 38


thermoplastic hoses (so far the most widely used), austenitic stainless steel type 316L, duplex grades and superduplex Sandvik SAF 2507. Even more exotic materials, such as e.g. titanium and zirconium, can be considered when very corrosive solutions are to be injected. With developments at

gre-

ater depths the demands put on the materials will increase with regard to mainly mechanical properties such as tensile strength and fatigue limits. Process systems

Process systems, consisiting of various vessels, heat exchangers, separators, compressors etc. for processing of the well fluid, are normally situated on the platforms. Carbon steels have traditionally been used to a great extent. However, the use of CRAs is increasing and today austenitic type 3R60 and duplex grade SAF 2205 are widely used alloys. 3R60 is usually sufficiently corrosion resistant with respect to the oxygen free process fluids. With sea water very close to systems, the air surrounding them will be very chloride rich. If the tubes are exposed to this chloride rich air or even splashes of actual sea water, the risk for externally induced chloride stress corrosion cracking of 316L materials is evident. Therefore duplex SAF 2205 should be considered. The upper temperature limit for SAF Figure 10. Oil platform with static umbilicals controlling subsea wells.

2205 is not well defined and for the highest internal temperatures superaustenitics or nickel based alloys can be chosen.

Table 9: Review of CRA materials used for different systems in an offshore oil/gas extracting unit. Function

Material used

Comment

Down Hole (often in a cold

Mar tensitic 13Cr

wor ked condition)

Duplex SAF 22Cr

For CO2 rich wells with no or low levels of H2 S For wells with reasonable amounts of H2 S For severe conditions with regard to mainly H2 S levels Perhaps more used in the future

Ni-rich alloys such as e.g. Sanicro 28 Flowlines

Carbon Steel lined with CRA ”Super”-13Cr Duplex SAF 2205 Superduplex SAF 2507 Austenitic 254 SMO Ni-rich alloys

Umbilicals

Process systems, topside

Sea Water systems

CO2 containing fluids, low H2 S contents Reasonable H2 S levels More corrosive environments Cl- , ox yg en , H2 S More corrosive environments Cl- , ox yg en , H2 S Severe conditions

SAF 2507

For a wide range of corrosions and high pressure applications.

Plastic Hoses Exotic

Traditionally most widely used. U nsuitable for many chemicals and in deep water.

Exclusive materials (Ti, Zr)

For ver y corrosive chemicals

Weld ed du pl ex tub es

Sl ig htl y le ss cor ro si on re is ta nt an d lo wer me cha ni cal properties than seamless SAF 2507

Austenitic type 3R60

If maximum temperature below 60°C

Duplex type SAF 2205

If minimum temperature above -46°C

Austenitic type 254 SMO

If temper ature r ange below -46°C and above 60°C

CuNi alloys

Insufficient resistance to erosion attacks

Austenitic 254 SMO

Max temperature 15-30°C if crevices

Superduplex SAF 2507

Max temperature 15-30°C if crevices

GRP

Max 80°C

Titanium

Max 80°C if crevices

I: 39


Sea water systems

Among the many metals and alloys that are available, relat-

On the platforms, sea water is used mainly for three purposes:

ively few can be used for construction of process equipment

for the cooling water systems, as ballast water and perhaps

and piping. For practical purposes, corrosion in refineries and

most important for the fire water systems. For these systems

petrochemical plants can be classified into low-temperature

carbon steels and copper-nickel alloys have been used to a

(wet) corrosion and high temperature corrosion. Low-temper-

great extent. Carbon steels do however corrode and have to be

ature corrosion is considered to occur below about 300°C and

replaced after a certain time period and copper-nickel alloys

in the presence of water while high-temperature corrosion

are susceptible to erosion corrosion in sea water. Different

does not necessarily demand the presence of water. This sec-

stainless steel grades and plasti cs as well as titanium have the-

tion deals only with the field of low-temperature corrosion.

refore increasingly been selected in the last few years. Titanium and GRP (Glassfibre Reinforced Plastics) have

CORROSION

satisfactory properties with regard to corrosion resistance in

Refinery applications

sea water but there have been reports on failures of these

The major cause of corrosion from the process side in a re-

materials due to quality problems. High alloyed stainless steel

finery is not the hydrocarbons themselves but the presence of

grades such as austenitic 254 SMO (which has been widely

contaminants in the crude oil as it is produced. Although

used in the Norwegian sector of the North Sea) and super-

some contaminants are removed during preliminary treating

duplex SAF 2507 can be alternatives. In chlorinated systems

in the fields, most end up in refinery tankage, along with con-

with these stainless grades the temperature must not exceed

taminants picked up during the transportation. Examples of

30°C due to the risk of crevice corrosion. For the tightest

crude oil contaminants that affect the corrosion resistance of

crevices such as e.g. threaded connections, the upper temperature limit for 6Mo and superduplex materials can be even lower.

a steel are CO2, H2S, nitrogen compounds, sulphur compounds and inorganic chlorides such as NaCl, MgCl2 or

In Table 9, the use of different corrosion resistant materials is

CaCl2. Often, the actual corrodants are formed during initial refinery operations. An example of this is the hydrolysis of

summarised.

salts during preheating of distillation feedstock, which results in the formation of hydrochloric acid.

Corrosion in petroleum refining and petrochemical applications INTRODUCTION

Corrosion has always been an unavoidable part of petroleum refining and petrochemical operations. Although certain material problems are caused by other factors, a predominant number are due to various aspects of corrosion. Operating and maintenance costs are substantially increased due to corrosion problems. Scheduled and unscheduled shutdowns for repairing corrosion damage in piping and equipment can be extremely expensive and anything that can be safely done to keep a process unit running for long period of time will be of great benefit. A significant proportion of corrosion problems are actually caused by shutdowns. When equipment is opened to the atmosphere for inspections and repair, metal surfaces

Wet corrosion on the process side may also be caused by chemicals added to the process such as various alkylation catalysts, certain alkylation by-products, organic acid solvents, stripped hydrogen chloride, caustic soda and neutralisers that, ironically, are added to control acid corrosion. In some production units it is the water used, rather than the process fluids, that causes corrosion. The cooling water can vary in chloride content from virtually nil in de-ionised and fresh water up to 1.5% in seawater. Cooling and process water sources may also be polluted with sulphides, ammonia and carbon dioxide among others as well as carrying entrained solids. These factors, together with temperature and pH dictate the corrosivity of the water and careful consideration must be given to materials selection.

covered with corrosive products will be exposed to air and moisture. This can lead to pitting corrosion and stress corro-

Petrochemical applications

sion cracking unless preventive measures are implemented.

Improvements in production economy can involve the use of

When equipment is washed with water during a shutdown,

higher temperatures and pressures, consequently placing

corrosion can be caused by pockets of water left to dry. When

higher demands on materials of construction. Important

the processes are running, there are basically two corrosive

reasons for corrosion on the process side are different aggres-

environments to consider, corrosion caused by process fluids

sive mixtures of chemicals and hydrolysis of organic chlor-

and, in the case of heat exchangers, corrosion caused by

ides, which may lead to formation of hydrocloricacid.

cooling water.

I: 40


The presence of organic acids in some processes may also

SAF 2205 and SAF 2304 have also been successfully appli-

introduce corrosion problems for several common steel

ed. Under severe conditions, for instance at high temperatures

grades. The reactive acid group (-COOH) is often r esponsible

and at high chloride contents, it might be recommended to use

for corrosion attack. The corrosion behaviour of metals in

high alloyed grades like Sanicro 28, Alloy 825 or SAF 2507.

organic acids is characterised by the slightly reducing condi-

If the temperature is above 300°C, super austenitic grades or

tions of the acids. Halide ions are usually present and may

titanium are the safest options. Other materials used to fight

cause severe attack on the standard austenitic stainless steels.

corrosion are copper based alloys, brasses and bronzes and nickel based alloys and titanium.

MATERIALS SELECTION

For cooling systems in fresh and brackish water, SAF 2205 is

Refinery applications

Figure 11 shows a simplified flow diagram of a refinery. In

an appropriate material, whereas SAF 2507 is needed where

the oil refinery process, each step presents different kinds of

seawater cooling is utilised. Other materials commonly used

corrosion problems which sometimes demand different

in seawater are copper based alloys and titanium.

material solutions. The main properties to take into consideration are however similar. Carbon steels are often used but may

Copper based alloys may suffer from erosion corrosion dam-

suffer from general corrosion. Conventional stainless steels

age at flow rates occurring in seawater cooled heat ex-

like AISI 304 and AISI 316 are prone to stress corrosion

changers whereas SAF 2507 withstands fluid velocities far

cracking (SCC) in chloride bearing environments. The ferritic

above those likely to be experienced in heat exchanger appli-

grade AISI 430 is not sensitive to SCC but suffers from a pre-

cations [1]. Table 10 presents some examples of critical appli-

dominant risk of pitting. The duplex grades are resistant to

cations in the oil refinery where corrosion resistant alloys

SCC Grade 3RE60 has been in service for several years. Later

may be used to solve specific problems [3].

Table 10. Some examples where stainless steels have solved corrosion problems. Description

Service conditions

Materials selection

Crude oil desalter

Tube side: Waste water with

After experiencing rapid corrosion on carbon steel and pitting of

feed water heater

700-900 ppm chloride , p H 6.

the ferritic grade AISI 410, Sandvik duplex stainless steel 3RE60

Te mp : I nl et : 19 0°C , O utl et : 75 °C

w as i ns ta ll ed a nd l as te d f or 1 7 ye ar s b ef ore e xc es si ve c or ro si on

S he ll si de : F ee d w at er wi th 2 p pm

o n t he ca rb on st ee l s he ll di ct at ed th at th e w ho le un it be re pl ac ed .

chloride, p H 7.1.

The unit was replaced with heat exchangers fabricated in SAF 2205.

Temp: Inlet: 35°C, Outlet: 145°C Atmospheric distillation

Tube side: Distilled hydrocarbon fractions.

F ee d E ff lu en t E xc ha ng er s Te mp : I nl et : 1 88 °C , O ut le t: 1 96 °C

Chloride containing water became trapped under deposits of h yd ro ca rb on s a nd t he re by c au se d c or ro si on o n c ar bo n s te el .

S he ll si de : C ru de oi l f ee ds to ck wi th

S AF 25 07 h as no w b ee n i ns ta ll ed an d s ol ve d t he pr ev io us

produced water.

problems.

Temp: Inlet: 149°C, Outlet: 157°C H yd ro de su lp hu ri sa ti on F e ed /E ff l ue nt Ex ch a ng e r

T ub e s id e: R ea ct or e ff lu en t w it h 0 .1 % H2 S and 10 ppm Cl - . Te mp : I nl et : 35 0°C , O ut le t: 2 00 °C Shell side: Feed with 10-20 ppm H 2 S and 10 ppm Cl - .

H yd ro ge n s ul ph id es a nd am mo ni um h yd ro su lp hi de ar e a gg re ss ive to carbon steel, a nd the 300 series suffer from SCC . S AF 2205 h as so lve d t he pr obl em s a nd al so en ab le d a re du ct io n i n w al l thickness.

Temp: Inlet: 70°C, Outlet: 230°C Gas Cleaning

Tube side: Steam

The carbon steel condenser s failed and corrosion tests indicated

Shell side: Amines, CO2 , cyanide controlled

that 304L would suffer from both pitting and SCC, while S AF 22 05 wo ul d pe rf or m we ll . F in al ly S AF 2 20 5 w as s el ec te d.

Vacuum Distillation

by polysulphide addition, NH3 and H 2 S . Tube side: Seawater

Surface Seawater

Temp: Inlet: 24°C, Outlet: 35°C

sand entrained in the seawater had caused failure by erosion

C oo le d C on de ns er s

S he ll s id e: Hy dr oc ar bo ns + 3% H2 , 5 .4 %N 2 , 0.5%CO 2 and 11%H 2 S.

c or r os io n a t fl ow r at e s as l ow a s 1. 5 m/ s.

SAF 2507 has been used to replace admiralty brass for which

Temp: Inlet: 55°C, Outlet: 127°C

I: 41


LPG GAS FROM OTHER UNITS GAS PLANT

POLYMERISATION

ALKYLATION

CRUDE DISTILLATION GAS

ETHERS LIGHT NAPTHA

ISOMERIZATION

HEAVY NAPTHA

HYDROTREATER/ REFORMER

GASOLINE

AROMATICS EXTRACTION

CRUDE DESALTER

AROMATICS LIGHT GAS OIL

HYDROTREATERS

CRUDE OIL

JET FUEL DIESEL

HEAVY GAS OIL

CRACKERS HEATING OILS

LUBE PLANT

LUBES ASPHALT

LUBES ASPHALT

RESID COKE COKER

Figure 11. Simplified flow diagram of refinery processes.

Petrochemical applications

in cooling water. These materials represent alternatives to

Amongst the vast array of materials in the chemical industry,

sometimes very expensive metallic materials at comparable

the iron and nickel based alloys play the most important role.

corrosion resistance. However, the allowable service pres-

The requirements and aspects for materials selection in a

sures are limited and for most of them the service temperature

chemical plant is a balancing act between safety, economy,

should not exceed 100°C.

process and product requirements. The chemical process industry contains many additional corStainless steel is often the natural choice of material for vital

rosive environments where significant advantages can be

equipment in the petrochemical industry. The general mater-

realised by selecting DSS for construction materials. One

ials selection considerations described for refineries, for

interesting field is the application of DSS under conditions

instance regarding cooling water, also apply to a large extent

where Ni-rich steels or alloys are attacked by complexing

to petrochemical applications. When organic acids are present

reactions. An example of this is that DSS perform very well

on the process side, the duplex family of steels have wide

in columns for ammonia extraction in waste water treatment

application potential. Laboratory tests of duplex stainless

plants, whereas austenitic steels corrode severely.

steels in different mixtures of organic acids clearly show that SAF 2507 offers an alternative to Ni-based alloys in high

CONCLUSION

chloride containing organic acids, while SAF 2205 is a suit-

For efficient and safe plant utilisation in refineries and petro-

able alternative when the chloride levels are lower [2].

chemical industries material selection is becoming ever more

Polymers and plastics like polyethylene or polypropylene,

important. The bulk of stainless steels used today are the con-

and fibre-reinforced resins such as vinyl esters or epoxy, have

ventional austenitic grades. In an increasing number of cases,

excellent corrosion resistance in many aggressive media and

however, economic considerations, such as plant reliability

I: 42


and service life, justify the selection of higher higher alloyed

corrosion cracking [1]. Depending on the pulping process

special stainless steel grades.

used and the amounts of corrosive compounds in the pulp the location and extent of corrosion may differ.

REFERENCES

1. Sandvik Steel R&D lecture S-51-57-ENG: “SAF 2507 for sea water cooled heat exchangers” 2. Sandvik Steel R&D lecture S-51-55-ENG: “Application of duplex stainless steels in the Chemical and Petrochemical Industry” 3. Sandvik Steel brochure S-1541-ENG: “The Role of Duplex Stainless Steels in Oil Refinery Heat Exchanger Applications”

Where the corrosion rate of carbon steel in pulp digesters has become excessive, alternative solutions have been tried. Metallization, weld overlay and anodic pro-tection are some methods used to increase the digester life time. Several cases where the intended protection has caused locally increased corrosion rates have, however, been reported. To overcome these problems new digesters are being constructed of duplex stainless steels or compound sheet. The duplex stainless steel grade UNS S31803, corresponding to SAF 2205, has been used successfully for several years in the construction of

The pulp and paper industry

digesters and surrounding equipment, such as liquor heaters and tubing [2].

Corrosive environments are found in several stages in the production of pulp and paper. Process modifications, for increa-

WHITE LIQUOR REGENERATION

sed production, as well as for environmental considerations,

Regeneration of white liquor is performed in a series of steps.

have in recent years lead to remarkable changes in the

Weak black liquor is separated from the pulp in washers and

demand for improved corrosion resistance. Modified cooking

concentrated in multiple-effect evaporators. It reaches a solid

processes and the introduction of new bleaching chemicals

content of about 65% and consists mainly of sodium car-

are two examples. Sometimes a change from carbon steel to

bonate, thiosulphate, sulphite and sulphate, together with

stainless material can provide the solution, but on occasion

sodium salts of organic acids. In a black liquor recovery

special consideration should be given to material selction.

boiler (BLRB) combustion of the organic material takes place and the sodium sulphate is reduced to sulphide. A salt smelt

KRAFT PULPING

consisting of inorganic compounds is formed at the bottom of

Initially wood chips are heated with chemicals in a digester to

the boiler. Hydrogen sulphide has also been detected in reco-

split the lignin. In the Kraft process Na2S- and NaOH-containing white liquor is used. Chlorides, thiosulphates and

very boilers and the combination of these corrosive species at

metal ions are also present in the digester, emanating from the

The smelt from the furnace is dissolved in water, forming

chips or from recycled chemicals. Black liquor, i.e. used liquor

green liquor, and causticised by the addition of lime and heat.

and dissolved wood constituents, is formed during pulping.

After clarifying the solution white liquor has been regener-

Pulping actually consists of several steps, including cooking, extraction and washing, with heating steps according to special temperature programmes. The wood chips are added at the top and the white liquor somewhat below. A number of circulating systems are used for heating and washing of the pulp. In batch digesters the pulping programme proceeds simultaneously throughout the digester. Continuous digesters, on the other hand, are divided into different zones in which the different steps occur. Several modified continuous processes have been developed through the last decades, e.g. using counter-current liquor flows or isothermic cooking.

high temperatures makes this a very aggressive environment.

ated and may be returned to the digester. SAF 2205 is a good choice in the flash tank and the liquor evaporators, where the used black liquor is drawn out from the digester and concentrated before regeneration. Problems with stress corrosion cracking in the evaporators have been solved by the use of this grade [3]. The special environment in the recovery boiler demands the use of high temperature materials with good corrosion resistance. A good solution is to choose composite tubing, which has been used successfully in this application for more than 20 years. The tubes consist of carbon steel on the inside with good resistance

Traditionally, carbon steel has been used for pulp digesters

against steam corrosion. The shell side material can be

but at increased concentrations of hydroxides and sulphides

chosen to resist different conditions. Ordinary high temper-

passivation is not successful, with high corrosion rates as a

ature stainless steel which performs well in wall tubing can be

result. Other problems in this environment are intergranular

substituted by for instance Sanicro 38 for the bottom tubing.

corrosion of sensitised austenitic steel (AISI 304L) and stress

Composite tubing can also be used as superheater tubing

I: 43


where the most common combination is 3RE28/HT8. The shell side of this material consists of 25Cr/20Ni material whereas the tube side component is a ferritic steel especially suitable for high pressures and temperatures. See reference 4 for further information on composite tubing in BLRB applications. SULPHITE PULPING

Pulping can also be done using the sulphite process in which sulphur dioxide and bisulphate are the active chemicals. The pH of the cooking liquor is chosen to suit the process and wood type to a value between 1 and 10. The corrosion problems found in sulphite mills result from the generation of sul-

Figure 12. Composite tubes in a black liquor recovery

phuric acid, sometimes contaminated with chlorides. Sulphur

boiler at ASSI Lövholmen, Sweden. New air ports are

dioxide for the pulping is produced by the burning of ele-

being installed and the tube height is raised.

mental sulphur. Austenitic stainless steel can not be used in sulphur burning due to the formation of low-melting-point nickel sulphides. Carbon steel should be used for the sulphur burners and combustion chambers producing sulphur dioxide.

Table11. Materials choice in sulphite pulping Equipment

Materials choice

Sulphite digester (low chloride)

Sandvik 2RK65 or SAF 2205

In the sulphite pulping process AISI 316 steel has been the

Sulphite digester (high chloride)

SAF 2507 or 654 SMO

primary choice for construction material. Where higher c hlor-

Sulphur burners

Carbon steel

ide concentrations are found Sandvik 2RK65, SAF 2507 or

S ul ph ur c om bu st io n ch am be r s

C ar bo n st ee l

other Mo-bearing grades may be preferred. Molybdenum-

Sandvik 2RK65 or Sanicro 28

alloyed stainless steels can be used (at lower temperatures) if

Cooling towers for SO 2 gas Atmospheric absorption towers

the chloride concentration in the acidic solution is controlled.

Acid tanks

Sandvik 2RK65 or SAF 2205

Sandvik 2RK65

Chips in White Liqour in Wash Liquor

Steam

Upper, Spare and Lower Heaters Digester Wash Water Heater

Wash Liquor

Pulp to Blow Tank Figure 12. Pulp digester with flash tank and heaters.

I: 44

Steam Flash Tank Used Liquor to Evaporators


PULP BLEACHING

CORROSION IN THE PAPER MILL

Bleaching of pulp is actually a continuation of the de-

In the process of papermaking from bleached pulp no corro-

lignification process which started in the digester. It has

sives are added. Even so, several cases of corrosion failure

traditionally been performed by the use of chlorine containing

have been found due to remainders of aggressive ions in the

chemicals with an initial chlorination step (C), followed by

pulp. This illustrates the importance of controlling processes

alternative alkali extractions (E) and chlorine dioxide treat-

and environments throughout the production. If wet chloride

ments (D). This environment can cause severe problems with

containing pulp contaminates metal surfaces even AISI 316L

localised corrosion. For environmental reasons ECF (ele-

material has been found to corrode and fail. The attack will

mental chlorine free) and even TCF (totally chlorine free)

begin under the wet pulp, forming shallow pits. These may be

bleaching has been developed. In the ECF process chlorine

the starting point of cracks or deeper pits. In most cases these

dioxide is still used, whereas several combinations of steps

problems can be solved by controlling the environment, i.e.

have been tried to replace this in TCF bleaching. Among the

keeping metal surfaces clean, reducing chloride concentra-

new chemicals used are ozone (Z), peracetic acid and hydro-

tions etc. If this proves too difficult a change to a more resist-

gen peroxide (P). Ozone is highly oxidising and has proved to

ant grade such as Sandvik 2RK65, SAF 2205 or SAF 2507

be a problem for molybdenum-bearing stainless steels which

might be recommended.

suffer from local attacks, such as pitting. Intergranular corrosion has occurred in 316 ozone tubing due to the formation of

REFERENCES

nitric acid [3]. Hydrogen peroxide posses no threat for stain-

1. A Wensley, “Corrosion in digester liquors”, Proceedings

less steels, but the corrosion rates for titanium increase with increasing concentrations of the peroxide ion, HO2– , i.e.

of the 8th International symposium on Corrosion in the

with increased pH [5].

Sweden, 1995.

Pulp and Paper Industry, The Swedish Corrosion Institute, 2. P. H. Thorpe “Duplex Stainless Steel Pulp Digesters -

In chlorination steps titanium, plastic material or rubber is

Fabrication and User Experience in Australia and New

preferred for towers and tubing. Some nickel-base alloys in

Zealand”,

the 800 series, e.g. Sanicro 30 and Sanicro 41, have also

Symposium on Corrosion in the Pulp and Paper Industry,

proved successful. Stainless steels up to AISI 317 should be

The Swedish Corrosion Institute, Sweden, 1995.

Proceedings

of

the

8th

International

avoided as increased chlorine concentrations have been found

3. Sandvik Steel R&D Lecture S-54-29-SWE “Materialval

to cause crevice corrosion. Super duplex stainless steels, such

som löser korrosionsproblem inom cellulosaindustrin”

as SAF 2507, or high-Mo austenitic grades, like 654 SMO or

english ed. in print.

254 SMO perform well in chloridic environments and can be used in D towers and surrounding equipment. In the environ-

4. Sandvik Steel R&D Lecture S-54-26-ENG “BLRB composite tubes - 15 years of experience”.

ment formed by alkali extractions Sandvik 2RK65 shows

5. P Andreasson, “The corrosion of titanium in hydrogen

excellent performance. For the ozone environments SAF

peroxide bleaching solutions”, Proceedings of the 8th

2304 or other stainless steels which are low in molybdenum

International symposium on Corrosion in the Pulp and

are required, whereas any stainless steel can be chosen for the

Paper Industry, The Swedish Corrosion Institute, Sweden,

peracetic acid or peroxide environments normally used.

1995.

Table 12. Materials choice for bleaching equipment Equipment

Steel grade or other

Chlorination tower and piping, chemical lines and sewer lines

Titanium, Sanicro 30 or Sanicro 41

D -s te p to we r, p i pi ng a nd l in es

S AF 2 50 7 or 6 54 S MO

Z-step tower, piping and lines

SAF 2304 or Sandvik 2RE10

Peracetic acid or P step equipment

Sandvik 3R12 or 3R60

I: 45


8.

Fabrication

In this section, advice on design and fabrication of stainless

avoid tight crevices in which corrosion could develop.

steels is given, mainly related to tube materials.

Examples of such crevices are bolted joints, tube - tube sheet, tube isolation material, tube - biofilm etc.

Constructional design

Figure 2. Example of crevices in bolted joints and

In many cases corrosion damage can be attributed to unsatisfactory constructional design. Such damage is often unnecessary and could have been avoided if greater account had been taken for the risk of corrosion at the design stage. Another common reason for corrosion damage is unexpected service conditions. It is therefore important to try to predict possible changes from the normal condition. When a material corrodes only by general corrosion it is possible to predict its lifetime relatively well. Local corrosion, like pitting, crevice and stress corrosion, is more difficult to foresee. This kind of corrosion often leads to abrupt failure in a relatively short time and is therefore dangerous. There are several ways to minimise the risk of local corrosion at the design stage. One way to prevent pitting is to avoid stagnant corrosive media in for example horizontal tubes. This is

between tube and tube sheet.

because concentration of aggressive species occurs and pitting preferentially develops in the direction of gravity.

In the case of biofilm formation, it can often be prevented by chlorination of the media. However, chlorination has a negative effect because it increases the risk of local corrosion if the concentration is too high. If gaskets are used in joints it is important not to use chloride containing or porous material in the gaskets because this promotes crevice corrosion. Graphite gaskets are not permitted in combination with stainless steels due to the risk of galvanic corrosion. When designing equipment in austenitic stainless steel (ASS) it is important not to impose high tensile stresses in the mater-

Figure 1. Example of poor design.

ial. The reason for this is that ASS are prone to stress corrosion cracking in chloride containing media. Tensile stresses

If the medium is flowing the risk of deposits inside the tube

can also develop when the tube is welded, expanded, bent,

is also less. Clean surfaces decrease the risk of crevice corro-

assembled etc. The first three items will be considered later

sion that could develop between deposit and tube wall. One

on. When assembling tubes it is important that the tube has

way to solve this problem is through appropriate construc-

the final shape before assembling so that no force is applied

tional design that makes it possible to clean the inside of the

on the tube during or after mounting (see figure 3).

tube at certain intervals. Another way is to make sure that the medium is able to drain from the tube when a long interruption in production occurs. In chloride containing media it is particularly important to

I: 46


the weld deposit and heat affected zone (HAZ). That gives the best mechanical strength and corrosion resistance possible in the welded joint. There are two main points to be kept in mind when welding duplex stainless steels. A too high cooling rate will give a very ferritic structure containing chromium nitrides, which above all leads to inferior corrosion resistance. Thus, low energy welding processes and autogenous welding should be avoided unless full quench annealing can be done as post weld heat treatment. Figure 3. Example of good and poor assembling.

If on the other hand, the heat input is too high, precipitations One advantage with duplex stainless steels (DSS) is that they

of intermetallic phases can occur, which embrittle the weld

are less sensitive to stress corrosion cracking compared to

and lower its corrosion resistance.

austenitic stainless steels (ASS). Another advantage is that they have about twice the strength of ASS. This means that the thickness of the tube wall can be reduced and therefore result in lighter structures. Another thing to keep in mind at the design stage is that DSS have a coefficient of thermal expansion near that of carbon steel. This can be used to reduce stresses in the construction, which could be a problem if ASS are used. One advantage with the ASS is that they retain high impact

Suitable welding methods for duplex stainless steels are: TIG, MIG, MMA, SAW, PAW and FCAW. Spot welding can be done if the nugget is resistance heated 3-5 seconds period of time for good austenite reformation. The duplex filler metal is normally higher in Ni compared to the base material in order to give a correct ferrite content and further improve the austenite reformation at the fast temperature laps that are involved in welding.

toughness at low temperatures (below -50°C). The austenitic stainless steels of 18/8, 18/8Mo type possess excellent weldability. Generally speaking, however, the weld WELDING

ability declines with increasing alloy content. As a rule of thumb, high heat input and high interpass temperatures should be avoided. For austenitic steels having a carbon content larger than 0.06% a high heat input will cause sensitisation, which will lead to carbide precipitation in the grain boundaries in the HAZ and thus can cause intergranular corrosion if exposed to corrosive media. In order to give the high alloyed austenitic steels optimum weldability, they are produced with very low phosphorus and sulphur contents. These steels are sensitive to small amounts of impurities, which diffuse to grain boundaries and segregate to interdendritic areas. For this reason, the heat input shouldbe kept low (<1 kJ/mm and interpass temperature <150°C). In steels that solidify austenitically, Mo and Cr segregate. The dendritic areas will for this reason get a local reduction of the pitting resistance. To overcome this problem a filler metal, over alloyed with Mo and Cr to give sufficiently high pitting

Modern duplex stainless steels have in general as good weld-

resistance in the segregated areas is used.

ability as austenitic stainless steels. This is mainly the result of an optimised ferrite - austenite balance and of alloying with

For the 18/8, 18/8/Mo type the filler metal contains 8-12%

nitrogen, which gives an efficient reformation of austenite in

delta ferrite. This makes the weld solidify ferritically, which

I: 47


is a safer way to avoid hot cracking. For the high alloyed

resistant to stress corrosion cracking. However, in cases of

austenitic steels, ferrite must not be present as it would trans-

heavy cold deformation and severe service conditions, heat

form to sigma phase. Filler metals, low in impurities and

treatment is recommended.

sometimes with a higher manganese content are used instead. For ASS, which are sensitive to stress corrosion, heat treatAnother property of austenitic stainless steel that has to be

ment or less heavy bending is recommended. However, it is

kept in mind is the high coefficient of expansion, which

hardly possible to give general advice as to when heat treat-

causes buckling and distortions of the construction when

ment is necessary for either DSS or ASS. The decision is

welding.

influenced by many factors related to the application, such as temperature, pH, chloride content and stresses. If a lubricant

To avoid this, welding plans should be made up in advance.

has been used during the cold forming, it has to be removed

The duplex stainless steels have an advantage in this respect

before any heat treatment.

having a coefficient of expansion close to that of carbon steels.

Cold bending of tubes leads to wall thinning at the outer wall of the bend, the degree depending on bending radius and

The fabrication economy is often better when using DSS

bending method. Compensation for this must be made when

compared to ASS. The reason is that the higher strength

choosing the initial tube dimension. The spring back after

means thinner material thicknesses, which means shorter

bending DSS tubes is somewhat higher than for ASS.

welding time and less consumption of filler metals. Higher

Adjustments must thus be made to compensate for this.

arc energy can be used and less restrictions in interpass temperature are other advantages when welding DSS compared

Hot bending is used primarily for large tube diameters, heavy

to ASS. This also contributes to shorter welding time and

wall thicknesses and for small bending radii. For DSS the

improves the fabrication economy.

temperature should be around 1050°C dependent on grade selection and for low alloyed ASS a little less. High alloyed

Bending

ASS are usually not hot bent. If the temperature after the forming is high enough, quenching can be done directly from the working temperature. If the temperature is not known it is always recommended to perform a separate heat treatment.

Expanding into tube sheets Duplex stainless steels (DSS) and austenitic stainless steels (ASS) can be expanded by the same methods, though DSS require greater initial force. The expansion should be undertaken in a one-step operation to avoid problems with work hardening from the first step when performing the second step. When expanding tubes into tube sheets there is always a risk of subsequent stress corrosion. To avoid this, a close fit can be chosen to reduce the degree of cold work. Aiming typically for a 6-8% deformation of the tube wall. One disadvantage with expanding is that tight crevices develop and crevice corrosion could initiate. To avoid crevices, welding is sometimes Duplex stainless steels (DSS) can be cold formed by the same

performed. Welding also induces stresses, and the risk of

methods as for standard austenitic stainless steels (ASS). The

stress corrosion increases in the sensitive ASS. DSS are less

higher yield strength of DSS means that a higher initial force

prone to stress corrosion and from this point of view expan-

is required to plasticise the material. Once this limit is rea-

ding and tube to tube sheet welds are less complicated.

ched, the duplex materials flow as easily as standard austenitic steels. The work hardening effect is about the same.

When expanding ASS into carbon steel tube sheets consid-

Heat treatment to stress relieve the DSS after cold forming is

eration must be taken regarding the different thermal expan-

less often not required (compared to ASS) as the material is

sion during operation. This could lead to a loose joint if the

I: 48


stresses from thermal expansion become greater than the strength of the joint. This problem is of less significance for DSS, which have similar thermal expansion as carbon steel.

Figure 4. Expanding tubes into a tube sheet. Figure 5. The importance of different surface appearances for local corrosion resistance, illustrated

Surface properties

by different post weld cleaning processes.

For all stainless steels, proper cleaning after welding or heat treatment is necessary in order to obtain the best possible corrosion resistance. This is of particular importance when the

be allowed. Furthermore, separate grinding tools for stainless

construction is to be used in chloride containing environ-

and carbon steel are recommended, and carbon steel particles

ments, where there is a risk of pitting and crevice corrosion.

in the blasting medium must be avoided. Following all types

The reason is that chlorides concentrate under oxide scales

of mechanical cleaning it is appropriate to perform a passiva-

etc until a critical concentration is reached and local corrosion

tion treatment, which removes iron particles that could lead to

develops. Scale and heavy oxides must therefore be removed

corrosion damage.

before the structure is put into service. The corrosion resistance after grinding depends on the degree The cleaning can be done mechanically by brushing,

of abrading used. The smoother the surface is, the lower the

grinding, blasting or machining, or chemically in a pickling

risk of general corrosion. One disadvantage with grinding

bath, or with a pickling paste with a subsequent careful water

compared to pickling is that grinding can expose new areas

rinsing. From a corrosion resistance point of view pickling is

with low corrosion resistance, which can lead to corrosion

preferred because this treatment efficiently removes areas

damage.

with low corrosion resistance. One disadvantage with pickling is that it can give rough surfaces if performed too

Scratches and surface irregularities are sites of corrosion

long. If a very smooth surface is required, electropolishing

initiation. Therefore, care should be taken when handling the

may be carried out.

tube before installation. When the tube is in service in a medium where the protective chromium surface layer will be

The cleaning tool material must also be considered to avoid

unable to develop, it is even more important not to damage

contamination of the surfaces. Only stainless brushes should

the surface.

I: 49

Table 1. Steel grades. Manufacturing programme Designation In tables Sandvik

Chemical composition (nominal), % C Si Mn Cr Ni Mo

Others

Standards UNS

ASTM TP (AISI)

JIS

SUS304TP SUS304LTP/ SUS304LTB – – – SUS316TP SUS316LTP/ SUS316LTB – – – – – – –

18-10 (18-10)

Austenitic standard stainless steels 5R10 0.04 0.4 1.3 18.5 9 3R12 ≤0.030 0.5 1.3 18.5 10

– –

– –

S30400 S30403

304/304H 304L

≤0.030

17-12-2.5 (17-12-2.5)

3R19 6R35 8R40 5R60 3R60

0.4 ≤0.06 0.5 0.06 0.4 0.04 0.4 ≤0.030 0.4

1.3 1.3 1.8 1.7 1.7

18.5 17.5 17.5 17 17.5

9.5 10.5 11 12 13

– – – 2.6 2.6

N=0.14 Ti≥5xC Nb>10xC – –

S30453 S32100 S34700 S31600 S31603

304LN 321 347 316/316H 316L

3R60 U.G.1) 3R65 3R66 3R69 5R75 3R64 3R68

≤0.020

1.7 1.7 1.7 1.7 1.3 1.7 1.8

17.5 17 17.5 17.5 17 18.5 17

14 11.5 14 13 12 14.5 13

2.6 2.1 2.6 2.6 2.1 3.1 4.1

– – – N=0.18 Ti – N=0.16

S31603 S31603 S31603 (S31653) (S31635) S31703 –

316L(U.G.) 316/316L 316L (316LN) (316Ti) 317L –

N08904 S31002 S31050

(904L)3) – (310L) – (310 mod.) –

(17-12-2.5)

(18-13-3) 17-14-4 904L

Sanicro 28

≤0.030 ≤0.02 ≤0.030 ≤0.05 ≤0.030 ≤0.030

0.4 0.4 0.6 0.4 0.5 0.4 0.4

High alloy austenitic stainless steels 2RK65 ≤0.02 0.5 1.8 2RE10 ≤0.020 ≤0.15 1.8 2RE69 ≤0.020 ≤0.4 1.7 Sanicro 282) Sanicro 302) Sanicro 412) Sanicro 69 254 SMO2)

31 32 40 60 18 22

3.5 – 3.0 – 6.1 7.3

Cu=1.0 Ti=0.5, Al=0.3 Cu=1.7, Ti=0.8 Fe=10 N=0.20, Cu=0.7 N=0.50, Cu=0.5

N08028 N08800 N08825 N06690 S31254 S32654

– Alloy 800 Alloy 825 Alloy 690 – –

– – – – – –

2205

Duplex stainless steels (austenitic-ferritic) SAF 2304 ≤0.030 ≤1.0 ≤2.0 23 4.5 3RE60 ≤0.030 1.7 1.5 18.5 5 SAF 22052) ≤0.030 ≤1.0 ≤2.0 22 5

– 2.7 3.2

N=0.1 N=0.07 N=0.18

– – –

– – –

SAF 2507

SAF 25072)

S32304 S31500 S31803/ S32205 S32750

–

–

S44600 S30815 S32100 – – S31008 N08811/ N08810 N06600

446-1 – 321H – – 310S –

– – – – – – –

Alloy 600

–

S30403/ S30400 S31603; S31600 S30300 (S32900)

304L/304

–

316L/316

–

303 –

– –

254 SMO 654 SMO SAF 2304

1)U.G.

≤0.02

≤0.6

and nickel base alloys 20 25 4.5 Cu=1.5 24.5 20.5 ≤0.10 – 25 22 2.1 N=0.12

≤0.030

0.5 ≤0.030 ≤0.5 0.02 ≤0.5 ≤0.020 ≤1.0 ≤0.020 –

≤0.030

27 0.6 20 0.8 21.5 ≤0.5 30 ≤1.0 20 3 24

25

7

4

N=0.3

Material for high-temperature service 4C54 ≤0.20 0.5 0.8 253 MA 0.08 1.7 ≤0.8 6R35 ≤0.06 0.5 1.3 8R30H ≤0.08 0.6 1.5 8R41 0.06 0.4 1.3 7RE10 0.07 ≤0.75 1.8 Sanicro 31HT 0.07 0.6 0.6

26.5 21 17.5 17.5 16.5 24.5 21

– 11 10.5 10.5 13 21 31

– – – – – – –

N=0.2 N=0.17, Ce=0.04 Ti≥5xC Ti≥6xC,B Nb≥10xC – Ti=0.5, Al=0.5

Sanicro 70

≤0.05

≤0.8

≤2.0

≤1.2

0.4

0.8

16.5 72.5 –

Fe=10, Cu≤0.5

Hollow bar for machining SANMAC 304L 0.030 0.4

1.3

18.5 9.5

–

SANMAC 316L

≤0.030

0.6

1.7

17.5 12.5 2.6

–

5RA50 10RE51

≤0.05

0.4 0.5

1.8 0.8

18 26

– –

0.04

9.5 5

–

0.5 1.4

2)Included in NACE MR0175 3)In USA 4)Valid for SEW 400 = Urea Grade Sandvik, SAF 2304, SAF 2205, SAF 2507 and Sanicro 28 are trademarks owned by Sandvik AB

I:50

Mechanical strength Proof Tensile Elong. strength, Rp0.2 strength, Rm A, % MPa, min. MPa, min. min.

EN

BS

SS

Werkstoff-Nr.

AFNOR

1.4301 1.4306/1.4301

304S31/51 304S11

2333 2352

1.4301 1.4306/1.4301

Z6CN18-09 Z2CN18-10

210 210

515-690 515-680

45 45

1.4311 1.4541 1.4550 1.4436 1.4435/1.4436

– 321S31 347S31 316S33 316S13

2371 2337 2338 2343 2353

1.4311 1.4541 1.4550 1.4436 1.4435/1.4436

Z2CN18-10AZ – (Z6CNNb18-10) Z6CND17-12 Z2CND17-13

275 190 220 220 220

550-750 490-690 515-690 515-690 515-690

40 35 35 40 45

1.4435 1.4404/1.4401 1.4435 1.4429 1.4571 1.4438 1.4439

316S13 316S11 316S13 – – – –

2353 2348 2353 (2375) 2350 2367 –

1.4435 1.4404/1.4401 1.4435 1.4429 1.4571 (1.4438) 1.4439

(Z2CND17-12) Z2CND17-12/(Z6CND17-11) Z2CND17-13 Z2CND17-12AZ – Z2CND19-15 –

190 220 220 300 190 220 280

490-690 515-690 515-690 590-780 490-730 515-690 580-800

40 45 45 40 35 40 35

1.4539 1.4335 1.4466

– – –

2562 – –

1.4539 1.4335 1.4466/1.44654)

1.4563 1.4558 – – 1.4547 –

– NA15 – – – –

2584 – – – 2378 –

1.4563 1.4558 2.4858 – – –

230 210 270 255 220 205 240 240 300 –

550–720 500-670 580-780 540-740 550-750 520-690 590-750 ≥585 ≥650 –

35 35 30 40 40 30 30 30 35 –

1.4362 – 1.4462

– – –

2327 2376 2377

1.4362 1.4417 1.4462

Z2CN23-04AZ Z2CND18-05-03 Z2CND22-05-03

400 450 450

600-820 700-880 680-880

25 30 25

1.4410

–

2328

–

–

550

800-1000

25

1.4749 1.4835 1.4878 1.4941 – – –

– – 321S51 – – – NA15

2322 2368 – – – 2361 –

1.4749 1.4893 1.4878 1.4941 1.4961 1.4845 1.4876

– – – – (Z6CNNb18-10) Z12CN25-20 –

275 310 190 195 210 220 170

500-700 600-850 490-690 490-640 510-690 515-750 500-700

20 40 35 35 35 35 35

–

NA14

_

2.4816

–

245

550-750

30

1.4307/1.4301

304S11/ 304S31 316S13/ 316S33 – –

2352/ 2333 2353/ 2343 2346 2324

1.4301

Z2CN18-10/Z6CN18-09

210

515-680

45

1.4435/1.4436

Z2CND17-13/Z6CND17-12

220

515-690

45

215 485

500-700 620-800

45 20

1.4435/1.4436 1.4305 –

1.4305 (1.4460)4)

Z1NCDU25-20-04 Z2CN25-20 Z1CND25-22AZ – Z1NCDU31-27-03 – – – Z1CNDU20-18-06AZ –

Z10CNF18-09 –

I:51

Sandvik Steel Corrosion tables

I:52

Corrosion tables This Corrosion Tables section is a revised and expanded edition of the earlier Jernkontoret Corrosion Tables. The new edition has been compiled in cooperation between Avesta Sheffield AB and AB Sandvik Steel. The new corrosion data are based on laboratory tests performed at the research laboratories of the two companies. Data The tables are mainly based on results of laboratory tests, carried out with pure chemicals and water solutions nearly saturated with air. It must be pointed out that the corrosion rate can be quite different if the solution is free from oxygen.

Laboratory tests are not strictly comparable with actual service conditions, where the corroding medium often

contains impurities. These may in some cases increase corrosion, in others decrease it. In unfavourable cases, the increase can be very great. Before making the final selection of material, therefore, it is in many cases necessary to make tests. The best results of laboratory tests are obtained if the solution used is identical with that which occurs in practice. This includes any effect impurities may have on corrosion. It is even better to expose test pieces to the actual process or environment concerned. Weighing and microscopical examination of the test specimens after a certain period of exposure will give a good idea of the corrosion risks to be expected.

Symbols

Advice on materials selection

These corrosion tables use a number of symbols, having the following meanings: 0 = Corrosion rate less than 0.1 mm/year. The material is corrosion proof. 1 = Corrosion rate 0.1 – 1.0 mm/year. The material is not corrosion proof, but useful in certain cases. 2 = Corrosion rate over 1.0 mm/year. Serious corrosion. The material is not usable. p, P = Risk (Severe risk) of pitting and crevice corrosion. c, C = Risk (Severe risk) of crevice corrosion. Used when there is a risk of localised corrosion only if crevices are present. Under more severe conditions, when there is also a risk of pitting corrosion, the symbols p or P are used instead. s, S = Risk (Severe risk) of stress corrosion cracking. ig = Risk of intergranular corrosion. BP = Boiling solution. ND = No data. (Used only where there are no actual data to estimate the risk of localised corrosion instead of p or s).

When there is some doubt about the materials selection, it is always advisable to contact the technical service of the supplier of the material. It is very important to furnish full information about the corrosion conditions concerned.

All concentrations are given in weight-% and the solvent is water if nothing else is shown. The corrosion data apply to annealed materials with normal microstructure and clean surfaces, throughout.

Note that the remarks ig, p and s are normally only used where the symbol for general corrosion rate is 0 or 1. The iso-corrosion diagrammes are to be interpreted as follows: The lines, one for each alloy, represent a corrosion rate of 0.1 mm/year. At concentrations or temperatures above this line the corrosion rate is higher.

The following information is necessary: – Corrosion environment (including chemical formulae if possible). – Concentrations (if possible also pH). – Content of impurities, e.g. Cl–, oxidising agents etc. – Temperature. Information concerning the type of structure, preferably with sketches, drawings or process descriptions, previously used materials, flow velocities, temperature variations, service life requirements etc., is also very valuable.

Read this note These corrosion tables provide an initial guide to the selection of materials and are intended to facilitate understanding of the different types of corrosion damage that can arise due to poor materials selection. It is, however, well known that the performance of stainless steel in service can be profoundly affected by minor changes in the environment or use. Accordingly, Avesta Sheffield AB and AB Sandvik Steel make no warrianties, express or implied, and accept no liability, compensatory or consequential, for the performance of stainless steels in individual applications that may be based on the information provided in this publication. See also the full disclaimer on page 88. II:1

A ABIETIC ACID

ACETIC ACID

C19H29COOH

CH3COOH

Conc. % Temp.°C

Carbon steel 13% Cr-steel 18-2 18-10 17-12-2.5 18-13-3 17-14-4 904L Sanicro 28 254 SMO 654 SMO SAF 2304 2205 SAF 2507 Ti

cont.

100 275

Conc. % Temp.°C

1 90

1 100 =BP

5 20

5 50

5 75

5 100 =BP

10 20

10 75

10 100 =BP

20 20

0 0 0 0 0 0 0 0 0 0 0 0 0


1 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

1 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

1 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

80 106 =BP

99.5 200

100 20

100 80

100 100

2 2

2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1p 0 0 0 0 0

ACETIC ACID CH3COOH Conc. % Temp.°C

20 80

20 90

20 100 =BP

50 20

50 80

50 90

50 100

80 20

80 40

80 85


2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 0

2 2 0 2 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 0

2 2 0 2 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 0

1p 0

2 1 0 0 0

0 0 0 0 0

0

0

0

ACETIC ACID Temperature, C 140 °

Ti 18-2 17-12-2.5 SAF 2507

120 100

18-10

80 60 40 20 0

20

40

60

80 100 CH3COOH, weight-%

Isocorrosion diagram, 0.1 mm/year, in acetic acid. Shaded area represents risk of localised attacks on steel 18-10. Curve for steel 18-2 etc. coincides with the boiling point cur ve.

II:2

A ACETIC ACID + FORMIC ACID cont. Conc. CH3COOH, % Conc. HCOOH, % Temp.°C

5 5 BP


5 95 102

1 1 1 1 1 0 0 0 0 0 0

7 3 BP

8 2 BP

0 0 0 0 0 0 0 0 0 0

0 0

20 80 95

0 0 0 0 0 0 0 0 0 0

20 80 103

0 0 0 0 0 0 0

25 5 BP

30 6 200

2 2 2 2 2 2 2 2

1 1 1 1 0 0 0 0 0 0 0

0 0

40 60 90

40 60 105

50 5 BP

2 1 0 0 0 0 0 0 0 0

0 0

0 0 0 0 0 0

50 10 BP

50 15 BP

50 20 BP

50 25 BP

1 1 1 1 0 0 0 1 0 0

1 1

1 1

1 1

1 0

1 0

1 1 0

1 0 0

1 0 0

1 1 0

0

ACETIC ACID + FORMIC ACID Conc. CH3COOH, % Conc. HCOOH, % Temp.°C

50 50 BP


ACETIC ACID + POTASSIUM PERMANGANATE

60 40 90

1 1 0 0 0 1 1 0

60 40 109 =BP

0

0

0

0

80 20 95

80 20 113 =BP

0 0 0 0

0 0 0 0 0 0 0

0

90 10 BP

95 5 117 =BP

0 0 0 0 0 0 0 1 0 0

98 2 BP

0 0 0 0

99 1 BP

0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0

0

ACETIC ACID + SODIUM CHLORIDE

Conc. CH3COOH, % 91 Conc. KMnO4, % 9 Temp.°C 113 =BP


99 1 BP

0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0

ACETIC ANHYDRIDE (CH3CO)2O

Conc. CH3COOH, % 1 Conc. NaCl, % 1 Temp.°C 70


2 2 0p 0ps 0ps 0ps 0ps 0ps 0 0 0 0 0 0 0

1 5 50

0p 0p 0p 0p 0 0 0 0 0 0 0

3 4 BP

0ps 0ps 0ps 0ps 0 0 0 0 0 0 0

4 1 70BP

0ps 0ps 0ps 0ps 0ps 0 0 0 0p 0 0 0

7 5 70

1ps 0ps 0ps 0ps 0ps 0 0 0 0 0 0 0

7-10 8.5 80

1ps 0ps 0ps 0ps 0ps 0 0 0 0 0 0 0

10 5 BP

1ps 0ps 0ps 0ps 0ps 0 0 0 0 0 0 0

10 26 BP

1ps 1ps 1ps 1ps 0p 0 0 2 1p 0 0

25 26 BP

Conc. % Temp.°C

100 20

100 BP

1ps 1ps 1ps 1ps 0p 0 0


2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 1 1 0 0 0 0 0 0 0 0 0 0 0

0 0

II:3

A ACETONE

ACETYL CHLORIDE

ADIPIC ACID

(CH3)2CO

CH3COCl

HOOC- (C2H4)2 -COOH

Conc. % Temp.°C

100 BP

Conc. %

dry 100 BP

Temp.°C


2 1 0 0 0 0 0 0 0 0 0 0 0 0 0


moist

Conc. %

BP

2

2

1 0 0 0 0

1ps 0ps 0ps 0ps 0ps

0

0

ALUM potassium aluminium sulphate, KAl (SO4)2

Temp.°C

all conc. 100

all conc. 200


0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0

ALUMINIUM Al

Conc. % Temp.°C

2.5 90

2.5 BP

5.5 2090

5.5 BP

10 20

10 50

10 80

10 BP

15 50

15 BP

satd BP

Conc. % Temp.°C

molten 700


2 1 0 0 0 0 0 0

2 2

2 2

2 2

2 2

2 2

2 2

2 2

0 0 0 0 0

1 1 1 1 0

2 2 0 0 0 0 0 0

2 2

1 0 0 0 0

2 2 0 0 0 0 0 0

1 0 0 0 0

1 1

2 2

2 2

0 0

0 0 0 0 0

0 0

1 0

2 2 2 2 2 2 2 2

0

0

0

1

0

0

0

1

0

1

1


ALUMINIUM ACETATE

ALUMINIUM CHLORIDE

Al (OOCCH3)3

AlCl3

Conc. % Temp.°C

satd. BP

Conc. % Temp.°C


0 0 0 0 0 0 0 0 0 0 0 0 0 0


II:4

5 50

0ps 0ps 0ps 0ps 0ps

0

2

5 100

10 100

10 150

20 100

20 150

25 20

25 60

27.5 110

2 2 0ps 0ps 0ps 0ND 0ND

2 2 2 2 2 2 2 2 0ND 1ND

2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

2 2 2 2 2 1p 1p 1p

2 2 2 2 2 2 2 2 1ND 1ND

2 2 2 2 2 2 2 2 2 2

0ND 0ND 0ND 0

2 2 0ND 0

2 2 2 0

2 2 2 2

0p

2 2 2 0

2

0

A ALUMINIUM NITRATE

ALUMINIUM SULPHATE

Al (NO3)3

Al2(SO4)3

Conc. % Temp.°C

all conc. 20

Conc. % Temp.°C

0.5 50

1.0 20

2.3 5 10 101 101 20 =BP =BP

10 50

10 102 =BP

23 20

23 100

27 20

27 satd. 102 105 =BP =BP


0 0 0 0 0 0 0 0 0 0 0 0 0 0


2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2

2 2

2 2

2 2

2 2

2 2

2 2

2 2

2 0 0 0 0

2 0 0 0 0 0 0 0 0 0 0 2

2 2 0 0 0 0 0 0 0 0 0 0 0 0 1

2 1

2 0 0 0 0 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0 0 0 0 2

2 0 0 0 0 0 0 0 0 0 0 0

2 1 1 1 0 0 0 0 0 0 0 2

2 2

AMMONIUM ACETATE + POTASSIUM DICHROMATE

2

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 2

AMMONIUM ALUM

AMMONIUM BICARBONATE

NH4Al (SO4)2 x 12H2O

NH4HCO3

Conc.CH3COONH4, % Conc. K2Cr2O7, % Temp.°C

3 2.5 BP

Conc. % Temp.°C

10 BP

Conc. % Temp.°C

all conc. 20


2


2 2 2 2 0 0 0 0


0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0

2

AMMONIUM BIFLUORIDE

AMMONIUM BISULPHITE

NH4HF2

NH4HSO3

Conc. % Temp.°C

10 25

Conc. % Temp.°C

10 20

10 BP


2 2


2 1

2 2

0 0 0 0 0 0 0 0 0 0 0 0

1 0 0 0 0 0 0 0 0 0 0 0

2 1 1 1 1 1

2

1 1 1

2 2

If air is present, attacks by sulphurous and sulphuric acid can occur in the gaseous phase.

II:5

A AMMONIUM BROMIDE

AMMONIUM CARBONATE

NH4Br

(NH4)2 CO3 x H2O

Conc. % Temp.°C

1-5 20-50


Conc. %

2 2 0p 0p 0p 0p 0p 0 0 0 0 0 0 0 0

Temp.°C

all conc. 20

all conc. 100


0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0

AMMONIUM CHLORIDE NH4Cl Conc. % Temp.°C


1 20

1 100

5 BP

0p 0p 0p 0p 0p 0p 0p 0ND 0ND

0p 0p 0ps 0ps 0ps 0ps 0ps 0ND 0ND

0ND 0ND 0ND 0

0ND 0ND 0ND 0

AMMONIUM CHLORIDE + SODIUM PHOSPHATE Conc. NH4Cl, % Conc. Na3PO4 , % Temp.°C


II:6

40 1.2 100

0p 0ps 0ps 0ps 0ps 0ps

0

10 2050

10 90100

10 BP

10 135

20 2050

20 90

2 1p 0p 0ps 0ps 0ps 0ps 0ps 0 ND 0ND

0p 0p 0p 0p 0p 0p 0p 0ND 0ND



1p 1p 1ps 0ps 0ps 0ps 0ps

0p 0p 0p 0p 0p 0p 0p 0ND 0ND


0ND 0ND 0ND 0

0ND 0ND 0ND 0

0ND 0ND 0ND 0

0ND 0ND 0ND 0

0ND 0ND 0ND 0

0ND 0ND 0ND 0

AMMONIUM CHLORIDE + ZINK CHLORIDE Conc. NH4Cl, %

20

Conc. ZnCl2 , %

20

Temp.°C

65



0

0p

20 BP

50 115

2 2 1p 1ps 1ps 1ps 1ps 0ps 0 0 0 0 0 0 0

2 2 2 2 1ps 1ps 1ps 1ps 0c 0 0 1 0P 0pc 0

AMMONIUM CHLOROSTANNATE pink salt, (NH4)2 SnCl6 Conc. % Temp.°C

satd. at 20° 20 60


2 2 P 1p 0p 0p 0p 0p

2 2 P 2 2 2 1p 1p

0

0

A AMMONIUM FLUORIDE

AMMONIUM HYDROXIDE

NH4F

NH4OH

Conc. % Temp.°C

10 25


Conc. %

1 0 0 0 0 0 0 0 0 0 0 0 2

AMMONIUM NITRATE + AMMONIUM SULPHATE, NH4NO3 + (NH4)2SO4 Conc. % Temp.°C

in any proportions 60 120

Temp.°C

all conc. 0-BP


0 0 0 0 0 0 0 0 0 0 0 0 0 0 0


0 0 0 0 0 0 0 0 0 0 0 0 0

AMMONIUM OXALATE

AMMONIUM PERCHLORATE

(NH4)2 C2O4

NH4ClO4

Conc. % Temp.°C


1-8 20

0 0 0 0 0 0 0 0 0 0 0 0 0

5-20 100

Conc. % Temp.°C

10 20

10 BP

20 30

1 0 0 0 0 0 0 0 0 0 0 0


0 0 0 0 0 0 0 0 0 0 0 0 0

2 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0

Risk of pitting and stress corrosion cracking on stainless steels in presence of chlorides.

AMMONIUM PERSULPHATE

AMMONIUM PHOSPHATE

(NH4)2 S2O8

mono, (NH4) H2PO4 di, (NH4)2 HPO4 tri, (NH4)3 PO4

Conc. % Temp.°C


all conc. 20

0 0 0 0 0 0 0 0 0 0 0 0 0

Conc. %

all conc. 70

Temp.°C

0 0 0 0 0 0 0 0 0 0 0 0 0


1 0 0 0 0 0 0 0 0 0 0 0

all conc. 20100

0 0 0 0 0 0 0 0 0 0 0 0 0 0

II:7

A AMMONIUM SULPHATE

AMMONIUM SULPHIDE

AMMONIUM SULPHITE

(NH4)2SO4

(NH4)2S

(NH4)2 SO3

Conc. % Temp.°C


all conc. 20BP

2 0 0 0 0 0 0 0 0 0 0 0 0 0

Conc. %

Conc. % Temp.°C

all conc. 20

Temp.°C



1 0 0 0 0 0 0 0 0 0 0 0 0 0

AMMONIUM THIOCYANATE

AMYL ALCOHOL

AMYL CHLORIDE

NH4SCN

C5H11OH

C5H11Cl

Conc. % Temp.°C


all conc. 100

0 0 0 0 0 0 0 0 0 0 0 0 0 0

Conc. % Temp.°C

Conc. %

100 20100


Temp.°C


0 0 0 0 0 0 0 0 0 0 0 0 0 0

ANILINE

ANILINE HYDROCHLORIDE

ANTIMONY

C6H5NH2 Technical grade

C6H5NH2 x HCl

Sb

Conc. % Temp.°C

100 20

Conc. % Temp.°C


II:8

0 0 0 0 0 0 0 0 0 0 0 0 0 0


all conc. 20

5

satd. 20BP

0 0 0 0 0 0 0 0 0 0 0 0 0

all conc. 20

0p 0p 0p 0p 0p

0

Conc. % Temp.°C

molten 650


2 2 2 2 2 2 2 2

100

2 2 2 2

2 2 2 2 2 2 1ps

0

0

2

A, B ANTIMONY CHLORIDE

BARIUM CHLORIDE

BARIUM HYDROXIDE

SbCl3

BaCl2 x 2H2O

Ba(OH)2

Conc. % Temp.°C


all conc. 20

0p 0p 0p 0p 0p

0

Conc. % Temp.°C


6 100

23 100

molten



2 2 2 2 2 2 2

0

0

2

BARIUM NITRATE

BARIUM PEROXIDE

Ba(NO3)2

BaO2

Conc. % Temp.°C

all conc. BP


0 0 0 0 0 0 0 0 0 0 0 0 0 0

Conc. % Temp.°C


BENZALDEHYDE

BENZENE

C6H5CHO

C6H6

Temp.°C

100

Temp.°C


0 0 0 0 0 0 0 0 0 0 0 0 0 0


Conc. % Temp.°C


all conc. 0BP

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

BEER

10 95

0 0 0 0 0 0 0 0 0 0 0 2

Temp.°C


2070

0 0 0 0 0 0 0 0 0 0 0 0 0

20BP

0 0 0 0 0 0 0 0 0 0 0 0 0

II:9

B BENZENESULPHONIC ACID

BENZOIC ACID

C6H5SO2OH

C6H5COOH

Conc. % Temp.°C

5 40

5 50

5 60

10 40

10 50

10 80

10 100

20 50


2 1

2 2

2 2

2 1

2 2

2 2

2 2

2 2

0 0 0 0 0

0 0 0 0 0

2 1

0 0 0 0 0

1 0 0 0 0

2 1

2 2 2 2 1

2 2 2 2 1

0 0

0 0

100 20

0 0 0 0 0

0

1

1

2

1

2

2

2

2

2

Conc. % Temp.°C


BENZYL CHLORIDE

BERYLLIUM CHLORIDE

BISMUTH

C6H5CH2Cl

BeCl2

Bi

Conc. %

Conc. %

all conc. 100

Temp.°C

Carbon steel 13% Cr-steel 18-2 18-10 17-12-2.5 18-13-3 17-14-4 904L Sanicro 254 SMO 654 SMO SAF 2304 2205 SAF 2507 Ti

Temp.°C



0

BLOOD

Temp.°C

20

37

II:10

0p 0 0 0 0 0 0 0 0 0 0 0 0 0

0p 0 0 0 0 0 0 0ND 0 0 0



0

BORAX

BORIC ACID

sodium tetraborate, Na2B4O7 x 1OH2O

B(OH)3

Conc. % Temp.°C


Conc. % Temp.°C

all conc. 100


all conc. 20BP

molten

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 2 2

all conc. 20BP

2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

molten 500 550

650

0 0

1 1

2 1

2

2

2

Conc. % Temp.°C

4 BP

20 BP


2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

B, C BORIC ACID + NICKEL SULPHATE HYDROCHLORIC ACID Conc. B(OH)3, % Conc. NiSO4, % Conc. HCl, % Temp.°C


1.5 25 0.2 80

0ps 0ps 0ps 0ps

0

BORON TRICHLORIDE BCl3 Conc. % Temp.°C

100 20


2

0 0 0 0 0 0 0 0 0 0 0 0

Risk of pitting corrosion on stainless steels in presence of moisture.

BROMINE

BUTYL ACETATE

Br2

CH3COOC4H9

Conc. % Temp.°C

100* 20

0.03 20

0.3 20

1 20


2 2 2 2 2 2 2 1

2 2 0p 0p 0p 0p 0p 0p

2 2 1p 1p 0p 0p 0p 0p

2 2 2 2 1p 1p 1p 1p

2

0

0

0


20BP

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Conc. % Temp.°C


25BP

0 0 0 0 0 0 0 0 0 0 0 0 0 0

CALCIUM ARSENATE

C3H7COOH

C4H9OH

Temp.°C


BUTYRIC ACID

BUTYL ALCOHOL

Temp.°C

*Pure, waterfree

Ca3(AsO4)2 100 20

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

100 BP

2 2 1 0 0 0 0 0 0 0 0 0 0 0

Conc. % Temp.°C

all conc. BP


0 0 0 0 0 0 0 0 0 0 0 0 0 0

II:11

C CALCIUM BISULPHITE

CALCIUM CHLORIDE

Ca (HSO3)2

CaCl2

Conc. % Temp.°C

10 20

10 BP


2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 0


cont.

Conc. % Temp.°C

5 20

5 50

5 100

10 20


2 0p 0p 0p 0p 0p 0p 0p

2 1p 0p 0p 0p 0p 0p 0p

2 1p 0p 0p 0p 0p 0p 0p

0

0

2 1p 0p 0ps 0ps 0ps 0ps 0ps 0 0 0 0 0 0 0

CALCIUM CHLORIDE

CALCIUM HYDROXIDE

CaCl2

Ca (OH)2

Conc. % Temp.°C


10 50

10 100 -BP

2 1p 0p 0p 0p 0p 0p 0p

0

0


II:12

1 1 BP


0

25 100

40 100

62 155

73 176

Conc. % Temp.°C

2 1p 0p 0ps 0ps 0ps 0ps 0ps

CALCIUM HYDROXIDE + CALCIUM CHLORIDE Conc. Ca(OH)2, % Conc. CaCl2, % Temp.°C

10 135

0p

2 1p 0p 0ps 0ps 0ps 0ps 0ps 0c 0p 0 0P 0p 0 0

2 2 0p 0ps 0ps 0ps 0ps 0ps 0ND 0pc 0pc 0 0 0p 0

0ps 0s 0s 0 0s 0s 1p


2

all conc. 20BP

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

CALCIUM HYPOCHLORITE

CALCIUM HYPOPHOSPHITE

Ca(ClO)2

Ca (H2PO2)2

Conc. % Temp.°C


1 20

2 100

6 20

6 100

Conc. % Temp.°C

5 BP

1p 1p 0p 0p 0p 0p

2 2 1p 1ps 1ps 0ps 0ps 0ps

2 2 1p 1p 1p 0p 0p 0p

2 2 2 2 1ps 1ps 1ps 1ps

0

0

0

0


0 0 0 0 0 0 0 0 0 0 0 0

0

C CALCIUM NITRATE

CALCIUM SULPHATE

CALCIUM SULPHIDE

Ca (NO3)2

CaSO4

CaS

Conc. % Temp.°C


all conc. 100

0 0 0 0 0 0 0 0 0 0 0 0 0

CAMPHOR

molten

Conc. %

Conc. %

Temp.°C

all conc. 100

Temp.°C

all conc. 100

148


2 0 0 0 0 0 0 0 0 0 0 0 0 0 0


0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0

CARBON DISULPHIDE + SODIUM HYDROXIDE + HYDROGEN SULPHIDE

CARBON DISULPHIDE CS2

Temp.°C

20

Conc. % Temp.°C

100 2046

Conc. CS2, % Conc. NaOH, % Conc. H2S, % Temp.°C

0.1 0.5 saturated BP


0 0 0 0 0 0 0 0 0 0 0 0 0 0 0


1 0 0 0 0 0 0 0 0 0 0 0 0 0 0


0 0 0 0 0 0 0 0 0 0 0 0 0

CARBON MONOXIDE

CARBON TETRACHLORIDE

CO aqueous solution

CCl4

Temp.°C


100

0 0 0 0 0 0 0 0 0 0 0 0 0 0

Conc. % Temp.°C

100 20

100 76 =BP


0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Risk of pitting and stress corrosion cracking of stainless steels in presence of moisture.

II:13

C CARNALLITE

CELLULOID

CELLULOSE ACETATE

KCl x MgCl2

dissolved in acetone

dissolved in acetone

Conc. % Temp.°C


Saturated at 20°C 20 BP

2 0p 0p 0p 0p 0p 0p

2 1p 1ps 0ps 0ps 0ps 0ps

0

0

Temp.°C

20BP

Conc. % Temp.°C

20 20


2 1 0 0 0 0 0 0 0 0 0 0 0 0 0


2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

CHLORAMINE

CHLORIC ACID

CHLORIDE OF LIME

NH2Cl

HClO3

CaOCl2

Conc. % Temp.°C


all conc. 20

Conc. % Temp.°C

10 20


0p 0p 0p 0p 0p

0

100 20

Quantity of active chlorine, % 0.8 Temp.°C 20

2 2 2 2 2 2 1p 1p


0

1 BP

0ps 0ps 0ps 0ps

0p 0p 0p 0p

2 1 1 1 1 1 1

0

0

0

0

CHLORINE DIOXIDE

Cl2

ClO2


II:14

a 70

0 0 0 0 0 0 0 0

b 2060

b 60100

c 20

2 2 2 2 2 2 2 1p

2 2 2 2 2 2 2 2

1p 0p 0 0 0 0 0 0

d 20

1p 1p 1p 0p 0p

2 1ND

2

2 2 0

0

0

0

a)

dry gas 100% moist gas c) Aqueous soln 1 mg/l d) Aqueous soln 1g/l b)

Temp.°C


30 20

2 1p 1p 0p 0p 0p 0p

CHLORINE Conc. % Temp.°C

20 35

dry gas 20

moist gas 20

0 0 0 0 0 0 0

2 2 2 2

0 0

0

C CHLOROACETIC ACID

CHLOROBENZENE

(mono), CH2ClCOOH

C6H5Cl

Conc. % Temp.°C


80 30

80 35

80 40

80 45

80 50

0

0

0c

0

0

0

1c

0 0 0 0 0

0 0 0 0 0

0 0 0 0 0

0 0 0c 0 0

80 55

80 60

80 65

0 0

2 0 1c 0c

0c 0 1c 0c 0c

0

CHLOROHYDRIN

CHCl3

CH2ClCHOH x CH 2OH

Temp.°C


all conc 20

all conc BP

dry 100 62 =BP

1 0p 0p 0p 0p 0p 0p 0p


0 0 0 0 0 0 0

0

0

0

Conc. % Temp.°C


all conc . BP

Conc. % Temp.°C


2 2 1p 1p 0p 0p 0p 0p

2 2 2 2 2 1p 1p 1p

2 2 0p 0p 0p 0p 0p 0p

0

1

1


2 2 0

Conc. % Temp.°C

100 20

100 132 =BP


0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0

Risk of pitting corrosion of stainless steels in presence of moisture

CHLOROHYDRIN + HYDROCHLORIC ACID dry 100 BP

0

ClC6H4CH3 100 25

2 2

0

HOClSO2 10 25

2 1c

0 0 0 0 0 0 0

CHLOROTOLUENE

0.5 20

1c 0c


CHLOROSULPHONIC ACID

Conc. % Temp.°C

80 80

2

CHLOROFORM

Conc. %

80 70

dry 100 BP

moist

0

2

0 0 0 0 0

2 2 1ps 1ps 1ps

0

0

4 %CH2ClCHOH x CH2OH + 1.5 % HCl Temp.°C

95


2 2 2 2 2 2 2 2

2

BP

II:15

C CHROMIUM TRIOXIDE, chromic acid CrO3 Conc. % Temp.°C

2 75


2 100 =BP

5 80

5 100 =BP

10 40

10 BP

20 20

20 50

20 BP

40 20

40 40

50 20

0 0 0 0 0 0 0 0 0 0

2 2 2 2 2 2 2 2 2 2

0

2 2 1 1 1 1 1 1 1 1

2 2 2 2 2 2 2 2 2 2

0

1 1

1 2 2 2 2 2 2 2 2 2

1 2 2 2 2 2 2 2 2 2

0 0 0 0

2 2 2 0

1 2 2 0

2 2 2 0

1 2 2 0

2 2 2 0

2 2 2 0

0 0 0 0 0 0 0

2 2 2 2 2 2 2 2 0 0

0 0 0 1 0 0 0

2 2 2 1 2 2 2 1 1 1

0 0 0 0

0 0 0 0

0 1 1 0

1 2 2 0

0 0 0 0

0

1 1

CITRIC ACID C3H4(OH)(COOH)3 Conc. % Temp.°C

1 20

1 BP

5 2050

5 85BP

5 140

10 2040

10 85BP

25 20

25 40

25 85

25 100

25 BP

50 20

50 40

50 100

50 BP

70 BP


2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 0

2 2 0 2 0 0 0 0 0 0 0 0 0 0 0

2 2 0 2 0 0 0 0 0 0 0 0 0 0 1

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 2 0 0 0 0 0 0 0 0 0 0 0

2 2 0 2 0 0 0 0 0 0 0 0 0 0 1

2 2 1 2 1 1 1 0 0 0 0 0 0 0 1

Temperature, C 140

0

CHROMIC ACID

Temperature, C 140

CITRIC ACID

°

°

120

120 Ti

100

100

80

80

60

60

18-2 17-12-2.5

18-10 18-10

40

40 Carbon steel

20

0

20

40

60

80 100 CrO3, weight-%

Isocorrosion diagram, 0.1 mm/year, for chromic acid. Molyb- denum alloying leads to reduced corrosion resistance in chromic acid. Hence, steel 17-12-2.5 is less resistant than steel 18-10. Broken-line curve represents the boiling point.

II:16

20

0

20

40

60 80 100 C3H4(OH)(COOH)3, weight-%

Isocorrosion diagram, 0.1 mm/year, for stainless steels in citric acid. The chain-line curve represents solubility line. Broken-line curve represents the boiling point.

C COAL GAS

COBALT SULPHATE

town gas

CoSO4

Conc. % Temp.°C

Conc. % Temp.°C


0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Conc. %

all conc. 20BP

Temp.°C


3 65


COFFEE

0 0 0 0 0 0 0 0 0 0 0 0 0

Temp.°C

BP


0 0 0 0 0 0 0 0 0 0 0

COPPER ACETATE

COPPER CARBONATE

Cu(OOCCH3)2

alkaline, CuCO3 x Cu (OH)2

Conc. % Temp.”°C

1 0 0 0 0 0 0 0 0 0 0 0 0 0 0

COD-LIVER OIL


all conc. BP

Temp.°C

20

0 0 0 0 0 0 0 0 0 0 0 0 0


2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Saturated in 50% ammonia solution

COPPER CHLORIDE

COPPER CYANIDE

CuCl2

Cu(CN) 2

Conc. % Temp.°C


0.05 100 =BP

1 60

2-5 60

8 20

8 BP

8 135

Conc. % Temp.°C

saturated at 100°C BP

2

2

2 2 2 2 2 2 2 2 2 2 0p 2 2 2 0

2 2 2 2 2 2 2 2


2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

0p 0p 0p 0p 0p

1ps 1ps 1ps 1ps 1ps 0

2 1ps 1ps 1ps 1ps

0p 0p 0p 0p 0p

0

0

0

0

0p

II:17

C, D COPPER NITRATE

COPPER SULPHATE

Cu(NO3)2

CuSO4

Conc. % Temp.°C


all conc. 20BP

0 0 0 0 0 0 0 0 0 0 0 0 0 0

CREOSOTE + SODIUM CHLORIDE

Conc. Creosote, % Conc. NaCl, % Temp.°C


97 3 20

2 0p 0p 0p 0p 0p 0p

0

Conc. % Temp.°C


all conc. 20BP

0 0 0 0 0 0 0 0 0 0 0 0 0 0

CREOSOTE OIL

Temp.°C

20

BP


1 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

DETERGENTS

DEVELOPERS

alkaline or neutral, chloride free

for black and white

Conc. % Temp.°C


1 80

0 0 0 0 0 0 0 0 0 0 0 0 0 0

Temp.°C

20


2 0 0 0 0 0 0 0 0 0 0 0 0 0

DEXTROSE

DEXTROSE + SODIUM CHLORIDE

DICHLOROETHYLENE

starch syrup, pure

pH=5

C2H2Cl2

Temp.°C


II:18

20

0 0 0 0 0 0 0 0 0 0 0 0

Conc. NaCl, % Temp.°C


0.05 100


0

Conc. % Temp.°C


100 20BP

0 0 0 0 0 0 0 0 0 0 0 0 0 0

Risk of pitting and stress corrosion cracking of stainless steels in presence of moisture

E, F ETHER

ETHYL ALCOHOL

ETHYL CHLORIDE

diethyl ether, (C2H5)2O

ethanol C2H5OH

C2H5Cl

Temp.°C

20BP

Conc. %

all conc. 20BP

Temp.°C


0 0 0 0 0 0 0 0 0 0 0 0 0 0 0


Conc. % Temp.°C


0 0 0 0 0 0 0 0 0 0 0 0 0 0

100 20BP

0 0 0 0 0 0 0 0 0 0 0 0 0 0


ETHYL NITRATE

ETHYLENE BROMIDE

ETHYLENE CHLORIDE

C2H5NO2

dibromoethane C2H4Br2

dichloroethane, C2H4Cl2

Temp.°C

20

Conc. % Temp.°C


2 0 0 0 0 0 0 0 0 0 0 0 0 0 0


100 20

Conc. % Temp.°C

0 0 0 0 0 0 0 0 0 0 0 0


Risk of pitting corrosion of stainless steels in presence of moisture

100 20BP

0 0 0 0 0 0 0 0 0 0 0 0 0 0

FATTY ACIDS

FIXING SALT

oleic acid, stearic acid

acidic, temp 20°C

Conc. % Temp.°C

100 20

100 80130

100 150

100 180

100 235

100 300


0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

1 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2

2 2

2 2

1 0 0 0 0

1 0 0 0 0

2 0 0 0 0

0

0

0

Risk of pitting and stress corrosion cracking of stainless steels in presence of moisture

Conc. Na2S2O3, % Conc. K2S2O4, % Conc. Na2SO3, % Conc. H2SO4, %

40 2.5 -


2 2 0p 0 0 0 0 0 0 0 0 0 0 0

19 4.7 0.5

0p 0 0 0 0 0 0 0 0 0 0 0

II:19

F FLUOBORIC ACID

FLUORINE

FLUOSILICIC ACID

HBF4

F2

H2SiF6

Conc. % Temp.°C

20 50

Carbon steel 13% Cr-steel 18-2 18-10 17-12-2.5 18-13-3 1 17-14-4 904L Sanicro 28 254 SMO 654 SMO SAF 2304 2205 SAF 2507 Ti

35 30

moist gas 20

Conc. % Temp.°C

Temp.°C

dry gas 20


0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 2 2 2


35 50

0

1

cont.

1 1

2

1 60

1 65

1 70

1 75

0 0 1

1 0 1

0

0

1

0

1

0 0 0 0 0

0 0 0 0 0

FLUOSILICIC ACID H2SiF6 Conc. % Temp.°C


5 50

5 55

5 65

5 70

10 35

10 40

10 45

1

1 0 0 1 1 0

0 1 0

0

1 0

1

1

2 1 1

1 1

0

1

0

20 20

20 30

1

2

0 0 0 0

1

20 40

20 50

1 0 0 2 1 0

0

1 0 2

1 2

1

20 60

2 2 1 1 1 1 1 1 1 1

31 20

31 30

31 40

31 45

1 0 2

0 2

1 2 2 2

1

1 0 0

2 2 2 1

FLUOSILICIC ACID Temperature, C 100 °

80 SAF 2507

60

254 SMO

654 SMO

40 SAF 2304 20

17-12-2.5 0 5

904L 10

15

20

25 30 35 H2SiF6, weight-%

Isocorrosion diagram, 0.1 mm/year, in fluosilicic acid.

II:20

F FORMALDEHYDE

FORMIC ACID

formalin, HCHO, pure

HCOOH

Conc. % Temp.°C


cont.

all conc. 20BP

Conc. % Temp.°C

0.5 70

1 20

1 40

2 20

2 40

2 100

5 20

5 80

5 95

5 100 =BP

2 0 0 0 0 0 0 0 0 0 0 0 0 0 0


2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 0

2 2 0 2 1 0 0 0 0 0 0 0 0 0 0

2 2 0 2 1 1 0 0 0 0 0 0 0 0 0

FORMIC ACID HCOOH

cont.

Conc. % Temp.°C

10 20

10 60

10 90

10 101 =BP

25 20

25 80

25 90

25 1 00

50 20

50 50

50 70

50 80

50 100

65 60

65 100

80 20


2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 0

2 2 0 2 1 0 0 0 0 0 0 0 0 0 0

2 2 0 2 1 1 0 0 0 0 0 1 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 2 0 0 0 0 0 0 0 0 0 0 0

2 2 0 2 1 0 0 0

2 2 0 2 1 1 1 1 1 1 0 2 1 0 1

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 0

2 2 0 2 0 0 0 0 0 0 0 0 0 0 0

2 2 0 2 0 0 0 0 0 0 0

2 2 2 2 1 1 1 1 0 1 0 2 0 0 2

2 2 0 2 0 0 0 0 0

2 2 2 2 1 1 1 1 1 1 0 2 1 0 1

2 2 0 0 0 0 0 0 0

0

0 0

0 0 0

0

0 0

0 0 0 0

FORMIC ACID HCOOH Conc. % Temp.°C

80 107 =BP

90 20

90 40

90 60

90 80

90 100

90 106 =BP

100 20

100 60

100 101 =BP


2 2 2 2 1 1 1 1 1 1 1 2 1 1 1

2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 0

2 2 0 2 0 0 0 0 0 0 0 0 0 0 0

2 2 2 2 1 1 1 1 1

2 2 2 2 2 1 1 1 1 1 0 2 2 1 1

1 1 0 0 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0 0 0 0

0 0

0 0

2 2 0 1 1 1 1 0 0 0 0 1 1 1 1

0 0 0 1

II:21

F FORMIC ACID + FORMALIN + ACETIC ACID Conc. HCOOH, % Conc. HCHO, % Conc. CH3COOH, % Temp.°C


FORMIC ACID + POTASSIUM DICHROMATE

1 40 0.1 BP

1 0 0 0 0 0 0 0 0 0 0 0

FREON Fluorinated hydrocarbons

Conc. HCOOH, % Conc. K2Cr2O7, % Temp.°C

2 2.5 BP

Temp.°C

<200


2 0 0 0 0 0 0 0 0 0 0 0 0 0 0


0 0 0 0 0 0 0 0 0 0 0 0 0 0

FRUIT JUICES, WINES

FURFURAL C4H3OCHO

Temp.°C

20

BP

Conc. % Temp.°C

100 162 =BP

vapour 200


1 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0 0 0 0 0 0 0 0


2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2

If SO2 is used as preservative, a molybdenum-alloyed steel should be used

FORMIC ACID

0 0 0 0 0 0 0 0 0 0 0 0

FORMIC ACID

Temperature, C 140

Temperature, C 140

120

120

°

°

SAF 2507

904L 100

100

80

80

Ti

18-2 17-12-2.5

60

40

60

18-10

0

20

40

60

80 100 HCOOH, weight-%

Isocorrosion diagram, 0.1 mm/year, for stainless steels in formic acid. Broken-line curve represents the boiling point.

II:22

SAF 2304

40

0

20

40

60


Isocorrosion diagram, 0.1 mm/year, for stainless steels and titanium in formic acid. Broken-line curve represents the boiling point.

G, H GALLIC ACID

GELATINE

GLUCOSE

trihydroxybenzoic acid, C6H2(OH)3COOH Conc. % Temp.°C

Conc. %

25 BP


all conc. 20BP

Temp.°C


0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0

GLYCERINE

GLYCOL

C3H5 (OH)3

ethylene glycol, C2H4 (OH)2

Conc. %

all conc. 20

Temp.°C


all conc. 20

Temp.°C


HYDROCHLORIC ACID

hydrogen bromide, HBr

HCl

0 0 0 0 0 0 0 0 0 0 0 0 0


dry 20

moist 20

2

2

0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0

cont.

Conc. % Temp.°C

30 25

100 25

Conc. % Temp.°C

0.1 2050

0.1 100 =BP

0.2 20

0.2 50


2 2 2 2 2 2 2 1

0 0 0 0 0 0 0 0


1 1p p 1p 0p 0p 0p 0p 0ND

2 1p p 1ps 0ps 0ps 0ps 0ps 0ND

1 1p p 1p 0p 0p 0p 0p

2 1p p 1p 0p 0p 0p 0p

0ND

0ND

0ND

0ND

0

0

0


Temp.°C

0 0 0 0 0 0 0 0 0 0 0 0 0

HYDROBROMIC ACID

0

Temp.°C

all conc. 20

GUANO

Conc. %

0 0 0 0 0 0 0 0 0 0 0 0 0

Conc. %

0ND 0 0

0

0.2 100 =BP

0.2 130

0ND 0ND 0ND 0ND 0ND 0p

0.5 20

0.5 50

2 2 p 1p 0p 0p 0p 0p 0ND 0ND 0ND 0ND 0ND

2 2 2 2 2 2 p 2 p 1p 2 1p 0p 2 0p 0p 2 0p 0p 2 0p 0p 2 0p 0ND 0ND 0ND 1ND 0ND 0ND 0ND 0ND 0 2 0ND 0ND 0ND 0ND 0 1 0

0

0.5 100 =BP

1 20

II:23

H HYDROCHLORIC ACID HCl

cont.

Conc. % Temp.°C

1 50

1 60

1 80

1 100 =BP

2 20

2 60

2 100 =BP

3 20

3 60

3 70

3 80

3 100


2 2 2 2 1p 0p 0p 0p 0ND 0ND 0ND 1 0ND 0ND 0

2 2 2 2 2 1p 1p 1p 0ND 0ND 0ND 1ND 0ND 0ND 0

2 2 2 2 2 1ps 1ps 1ps 0ND 0ND 0ND 2 1ND 0ND 0

2 2 2 2 2 2 2 2 2 2 1ND 2 2 0 1

2 2 2 2 1p 1p 1p 0p 0ND 0ND 0ND 0ND 1ND 0ND 0

2 2 2 2 2 2 2 1p 1ND

2 2 2 2 2 2 2 2

2 2 2 2 1p 1p 1p 0p 1ND 0ND 0ND 2

2 2 2 2 2 2 2 1p 2 0ND

2 2 2 2 2 2 2 1p 2 2 2

2 2 2 2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2 2 2 2

2 0

2 1

2 1

2 2

2 2 2 2 2 2

0ND 2 2 0ND 0

0 0

HYDROCHLORIC ACID HCl Conc. % Temp.°C

5 20

5 35

5 50

5 60

5 70

5 102 =BP

8 60

10 2035

10 60

20 2035

30-37 20


2 2 2 2 2 2 2 1 1ND 1ND 0ND

2 2 2 2 2 2 2 2 1ND 2 0ND

2 2 2 2 2 2 2 2 2 2 0ND

2 2 2 2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2 1ND

2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2 1ND

2 2 2 2 2 2 2 2

2

2 1

2 1

2 1

2 1

2 1

2 2

1

1

2

2

2

HYDROCHLORIC ACID

HYDROCHLORIC ACID WITH CHLORINE

Temperature, C 120 °


Titanium 100

100 Sanicro 28

80

80 HCI

60

60 654 SMO

HCI+CI2

SAF 2507

40

20

40

17-122.5

254 SMO 904L

SAF 2304

0

2

4

6

8 10 HCI, weight-%

Isocorrosion diagram, 0.1 mm/year, in hydrochloric acid. Broken-line curve represents the boiling point.

II:24

20

0

20

40

60

80 100 HCI, weight-%

Isocorrosion diagram, 0.1 mm/year, for titanium in pure hydrochloric acid and hydrochloric acid saturated with chlorine. Broken-line curve represents the boiling point.

H HYDROCHLORIC ACID + ALUMINIUM CHLORIDE + IRON (II) CHLORIDE + IRON (III) CHLORIDE

HYDROCHLORIC ACID + CHLORINE Saturated solution, HCl + Cl2

1.8% HCl + 1.0% AlCl3 + 8.8% FeCl2 + 6.0% FeCl3 Temp.°C

100


2 2 2 2 2 2 2 2

0

HYDROCHLORIC ACID + COPPER CHLORIDE

Conc. % Temp.°C

5 100

10 90

15 80

20 37 60 25


2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

0

0

0

0

2

HYDROCHLORIC ACID + IRON (II) CHLORIDE

(or copper sulphate) Conc. HCl, % Conc. CuCl2, % Temp.°C

10 0.05 80

10 1.5 BP

25 0.05 25

25 0.05 50

37 0.05 25

Conc. HCl, % Conc. FeCl2, % Temp.°C

5 5 80

10 0.1 80

10 0.1 90

25 0.1 50

25 0.1 60

25 0.1 70


2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

0

0

0

2

0

0

2

2 2 2 2 2 2 2 2 2 2 2 2 2 2 0

2 2 2 2 2 2 2 2

0


1

2

HYDROCHLORIC ACID + IRON (III) CHLORIDE

HYDROCHLORIC ACID + OXALIC ACID

Conc. HCl, % Conc. FeCl3, % Temp.°C

10 0.1 50

10 0.1 90

10 0.1 104 =BP

25 0.1 40

25 0.1 50

Conc. HCl, % Conc. (COOH)2, % Temp.°C


2 2 2 2 2 2 2 2 2 2 0 2 2 2 0

2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

2

0

2


0.5 3 40

0.5 3 60

0

1

II:25

H HYDROCHLORIC ACID + SODIUM CHLORIDE

HYDROCYANIC ACID

HYDROFLUORIC ACID

prussic acid, HCN

HF

cont.

Conc. HCl, % Conc. NaCl, % Temp.°C

1 30 40

Conc. % Temp.°C

100 20

Conc. % Temp.°C

0.1 50

0.1 60

0.1 70

0.1 80


2 2 2 2 2 2 2 1p


2 2 0 0 0 0 0 0 0 0 0 0 0 0


0

0

0

1

0 0

0 0 0

0 0 0

1 0 0

0

0

0

0

75 30

100 20

0 2 2 2 2 2 2 2

0 1 1 1 1 1 1 1

2

2

0

HYDROFLUORIC ACID HF Conc. % Temp.°C

0.1 90


0.1 100 =BP

0.5 30

0.5 40

0.5 50

0.5 60

0.5 70

1 20

1 30

1 40

1 50

1 60

1 70

10 20

2 2

1 1 0 2

1 1

0

1

0 0 0 0 0

1 0 0 1

1 0

0

1

1

0

1 0

1

1

1 0 0 0 0 0 0 0 1 1 0 2

2 2 2 2 2 2 2 2 1 1

1

1

1

1

0 0

1 0

1 0

0

0

1 0

20 15

20 25

1 1 1

2 2

2 1 2

1 2 2 2 2

1

HYDROFLUORIC ACID

30 15

HYDROFLUORIC ACID



120 80 100

SAF 2304

60

80

SAF 2507

60

654 SMO

40

254 SMO

Carbon steel

40

904L

20

17-12-2.5

0

2

4

6

8 10 HF, weight-%

Isocorrosion diagram, 0.1 mm/year, for stainless steels in hydrofluoric acid.

II:26

904L

20

0

20

40

60

80 100 HF, weight-%

Isocorrosion diagram, 0.1 mm/year, in hydrofluoric acid. Broken-line curve represents the boiling point.

H HYDROFLUORIC ACID + IRON (II) SULPHATE

HYDROFLUORIC ACID + POTASSIUM CHLORATE + SULPHURIC ACID 1 % HF + 3 % KClO 3 + 9 % H2SO4

Conc. HF, % Conc. FeSO4, % Temp.°C

1.5 6 70

Temp.°C

60


2 2



2 1 1 1 1

2

2

HYDROGEN CHLORIDE GAS

HYDROGEN CHLORIDE GAS

HCl, dry

moist, HCl

Temp.°C

2040

100

250

400500

Temp.°C


0 0

1 1

1 2

2 2

0 0 0 0 0

1 1

1 1 1 1

2 2


0

20

1

0 0

1

HYDROGEN IODIDE HI Conc. % Temp.°C

10 20

100 20


2 2 2 2 1 1 1 0

0 0 0 0 0 0 0 0

Risk of pitting corrosion on stainless steels.

0

0

0

II:27

H, I HYDROGEN PEROXIDE H2O2 Conc. %

5

5

10

10

10

15

15

15

30

30

50

Temp.°C

12 50

20

4050

23

40

6080

22

3040

5080

27

4080

40


0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 1

0 0 0 0 0 0 0 0 0 0 0 0 2

0 0 0 0 0 0 0 0 0 0 0 0 1

0 0 0 0 0 0 0 0 0 0 0 0 2

0 0 0 0 0 0 0 0 0 0 0 0 2

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 1

HYDROGEN SULPHIDE

0 0 0 0 0 0 0 0 0 0 0 0 1

0 0 0 0 0 0 0 0 0 0 0 0 0 0 1

0 0 0 0 0 0 0 0 0 0 0 0 2

INK

H2S Conc. %

4 4 dry gas

Temp.°C

100

200


1 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

moist gas or saturated solution 20

Temp.°C


2 2 2 1ps 0 0 0 0

0

a 20BP

1p 0p 0p 0p 0p 0p 0p

0

IODINE a

b

c

d

b)

Iron tannate ink Synthetic, chloride free

0 0 0 0 0 0 0 0 0 0 0 0 0

a)

dry moist c) Aqueous solution 1% d) Aqueous solution 2% + 1% KI b)

Temp.°C

20

20

20

20


0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 2 2 2 2 1p 1p

2 1p 0p 0p 0p 0p 0p 0p

2 1p 0p 0p 0p 0p 0p 0

0

0

0

II:28

a)

IODINE + ETHYL ALCOHOL + SODIUM IODIDE

I2 Conc. %

b 20BP

2 % I 2 + 47 % C2H5OH + 2.4 % NaI Temp.°C

44


2 1p 0p 0p 0p 0p 0p 0p

0

I, L IODOFORM

IRON (II) CHLORIDE

IRON (III) CHLORIDE

CHI3

ferrous chloride, FeCl2

ferric chloride, FeCl3

Conc. %

a

a)

b

b)

Temp.°C


20

Crystallized Vapour

Conc. % Temp.°C

Conc. %

10 20

Temp.°C

50

0p 0p 0p 0p 0p 0p 0p

0p 0p 0p 0p 0p 0p

0

0


0.550 20100


0p 0p 0p 0p 0p 0p

0

2 2 2 2 2 2 2 1p

0

IRON (III) NITRATE

IRON (II) SULPHATE

IRON (III) SULPHATE

ferric nitrate, Fe(NO3)3

ferrous sulphate, FeSO4

ferric sulphate, Fe2(SO4)3

Conc. % Temp.°C

Temp.°C

all conc. 20


2 0 0 0 0 0 0 0 0 0 0 0 0 0 0


Conc. %

10 20

10 90BP

0 0 0 0 0 0 0 0 0 0 0 0 0 0

Conc. % Temp.°C

10 20BP


1 1 0 0 0 0

0

0 0 0 0 0 0 0 0 0 0 0 0 0

LACTIC ACID C2H4(OH)COOH

cont.

Conc. % Temp.°C

1 2050

1.5 20

1.5 100 =BP

5 20100

10 20100

10 101 =BP

20 80

20 101 =BP

25 2050

25 7590

25 100

30 2070

30 75100

30 102 =BP

50 2070


1 1 0 0 0 0 0 0 0 0 0 0 0 0 0

1 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 0

2 2 0 2 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 0

2 2 1 2 1 1 1 0 0 0 0 0 0 0 1

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

II:29

L LACTIC ACID C2H4(OH)COOH Conc. % Temp.°C

50 7590

50 95104

75 2090

75 100

75 110

80 2095

80 100

80 117 =BP

90 20

90 40

90 50100

90 127 =BP


2 2 0 1 0 0 0 0 0 0 0 0 0 0 0

2 2 1 2 1 1 1 1 0 0 0 0 0 0 1

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 1

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 0

2 2 1 2 1 1 1 0 0 0 0 0 0 0 1

2 2 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0

2 2 0 2 0 0 0 0 0 0 0

0 0 0

0 0 0

0 0 0

2 2 1 2 1 1 1 0 0 0 0 1 0 0 1

LACTIC ACID + POTASSIUM DICHROMATE 3 % C2H4(OH)COOH + 2.5 % K 2Cr2O7 Temp.°C

BP


2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

LACTIC ACID + SODIUM CHLORIDE

LACTIC ACID + SULPHURIC ACID

1.5-2 % C2H4(OH)COOH + 1.5-2 % NaCl Temp.°C BP

10-50 % C2H4(OH)COOH + 25 % H2SO4 Temp.°C BP



2 2 0ps 0ps 0ps 0ps

0

2 2 2 2 2 2 2 1 2 2 2 2 2 2 2

LACTIC ACID Temperature, C 140 °

18-2 17-12-2.5 904L

120 100 Ti

80 18-10

60 40 20

0

20

40

60 80 100 C2H4(OH)COOH, weight-%

Isocorrosion diagram, 0.1 mm/year, in lactic acid. Curve for steel 18-2 etc. coincides with the boiling point curve.

II:30

L, M LEAD

LEAD ACETATE

Pb, molten

Pb(CH3COO)2 x 3H2O

Conc. %

a

a

a)

b

b)

Temp.°C

400


2 1 0 0 0

900

900

2 2 2 2 2 2 2

0 0 0 0 0 0 0 0

Conc. %

In presence of oxygen Melt with oxidation inhibiting surface layer of charcoal

Temp.°C


2

all conc. 2090

all conc. BP

0 0 0 0 0 0 0 0 0 0 0 0 0 0

1 0 0 0 0 0 0 0 0 0 0 0 0 0

LEAD NITRATE

LITHIUM CHLORIDE

LITHIUM HYDROXIDE

Pb(NO3)2

LiCl

LiOH

Conc. %

all conc. BP

Temp.°C


0 0 0 0 0 0 0 0 0 0 0 0 0

LYSOL

Conc. % Temp.°C

10 BP

10 135

40 115





0

0p

0

Conc. % Temp.°C

2.5 220


2 2 1s 1s 1s 0s 0s

0

MAGNESIUM BISULPHITE Mg(HSO3)2

Conc. % Temp.°C

2 20

100 20BP

Conc. % Temp.°C

10 20

10 BP


1 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 0 0 0 0 0 0 0 0 0 0 0 0 0 0


2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 0


II:31

M MAGNESIUM CARBONATE

MAGNESIUM CHLORIDE

MgCO3

MgCl2

Conc. % Temp.°C


all conc. 20

0 0 0 0 0 0 0 0 0 0 0 0 0 0

Conc. % Temp.°C

2.5 20

5 BP


2 0p 0p 0p 0p 0p 0p 0p


0

0

MAGNESIUM SULPHATE

MALIC ACID

MgSO4

apple acid, C2H3(OH)(COOH)2

Conc. % Temp.°C


5 20

5 60

1 0 0 0 0 0 0 0 0 0 0 0 0 0 0

10 20

2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

10 60

20 20

2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

20 BP

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

26 BP

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

Conc. %

1

Temp.°C

20

550 100


1 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

MANGANESE CHLORIDE

MANGANESE SULPHATE

MnCl2

MnSO4

Conc. % Temp.°C


II:32

5 100

10 BP


0ps 0ps 0ps 0ps 0ps

0

0

10 135

20 100

50 BP

0ps 0ps 0ps 0ps 0ps



0p

0

0

Conc. % Temp.°C

all conc. 20


0 0 0 0 0 0 0 0 0 0 0 0 0 0

23 BP

0 0 0 0 0 0 0 0 0 0 0 0 0

M MERCURIC CHLORIDE

MERCURIC CYANIDE

HgCl2

Hg(CN) 2

Conc. % Temp.°C

0.1 20

0.1 BP

0.7 20

0.7 BP


2 2 1p 1p 0p 0p 0p 0


2 1p 1p 0p 0p 0p 0

2 2 2 2 1ps 1ps 1ps

0

0

0

0

1-10 100

0

1-10 135

Conc. % Temp.°C

5 20

0p


2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

MERCURIC NITRATE

MERCURY

METHYL ALCOHOL

Hg(NO3)2

Hg

methanol, CH3OH

Conc. % Temp.°C

5 20

Temp.°C


0 0 0 0 0 0 0 0 0 0 0 0 0 0 0


20400

Conc. % Temp.°C

0 0 0 0 0 0 0 0 0 0 0 0 0 0


METHYL CHLORIDE

METHYLENE CHLORIDE

CH3Cl

CH2Cl2

Conc. % Temp.°C


Conc. %

100 dry 20

0 0 0 0 0 0 0 0 0 0 0 0

Temp.°C



0 0 0 0 0 0 0 0 0 0 0 0 0 0s

MILK

all conc . BP

100 dry 40 =BP


0 0 0 0 0 0 0 0 0 0 0 0 0 0

0

100 65 =BP

fresh

sour

Temp.°C

20

BP

20


1 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

II:33

M, N MUSTARD

NAPHTALENE C10H8

Temp.°C

20


2 1p 0p 0p 0p 0p 0p 0p

Risk of pitting increases with increasing amounts of salt and vinegar in mustard. Steel 17-12-2.5 can be used in equipment for mustard-making if it is cleaned regularly.

0

Temp.°C

25


0 0 0 0 0 0 0 0 0 0 0 0 0

NICKEL CHLORIDE

NICKEL NITRATE

NICKEL SULPHATE

NiCl2

Ni(NO3)2

NiSO4

Conc. % Temp.°C

10 20


10 100

2 1p 0p 0p 0p 0p 0p 0p


0

0

Conc. %

Conc. %

Temp.°C

510 20

Temp.°C

all conc. BP


2 0 0 0 0 0 0 0 0 0 0 0 0 0 0


2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

NITRIC ACID HNO3 Conc. % Temp.°C


II:34

cont. 0.5 250

0 0

0

0

1 20

1 50

1 100 =BP

5 20

5 50

5 100 =BP

5 150

5 290

10 20

10 50

10 101 =BP

10 145

20 20

20 50

20 103 =BP

2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 2 1 1 1 1 1

2 2 2 2 2 2 2 2

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 0 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0

2 2 0 0 0 0 0 0

0

2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 2 2 2 2 2 2

0

2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0

0

0

0

N NITRIC ACID HNO3

cont.

Conc. % Temp.°C

20 120

30 20

30 70

30 106 =BP

30 120

50 20

50 70

50 90

50 110

50 117 =BP

60 20

60 60

60 100

60 121 =BP

65 20

65 60


2 2 2 1 1 1 1 1

2 0 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0 0

2 2 1 0 0 0 0 0 0

2 2 2 1 1 1 1 1

2 0 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0 0

2 1ig 1ig 0ig 0ig 0ig 0ig 0ig 0ND

2 2 1ig 1ig 1ig 1ig 1ig 0ig 0ND

2 2 2 1ig 1ig 1ig 1ig 1ig 0ND 1ig

2 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0

2 2 1ig 1ig 1ig 1ig 1ig 0ig

2 2 2 1ig 1ig 1ig 1ig 1ig

2 0 0 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0 0 0 0 0 0 0

1

0 0 0

0 0 0

0 0 1

Conc. % Temp.°C

65 70

65 90

65 121 =BP

65 175


2 1 0 0 0 0 0 0 0 0

2 1ig 1ig 1ig 1ig 1ig 1ig 0ig 0ig 0ig

0 0 0 0

0ig 0ig 0ND 0

2 2 2 1ig 1ig 1ig 1ig 1ig 0ig 1ig 1ig 1ig 1ig 1ig 0

1

0 0 0

0 0 0

0ND 0ND 1

0ND 0ND 1

0ig 0ND 0ND 1

0

0

1

0

0 0 0 0

80 20

80 50

80 80

80 106 =BP

90 20

90 80

90 94 =BP

94 30

97 25

99 25

99 40

99 84 =BP

2 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0

2 2 1ig 1ig 1ig 1ig 1ig 1ig

2 2 2 2 1ig 1ig 1ig 1ig

2 0 0 0 0 0 0 0

2 2 2 2 2 2 2 1ig

2 2 2 2 2 2 2 2

2 2 0 0 0 0 0 0

2 2 0 0 0

2 2 1 1 1 1 1 1

2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

0

0

0

0

0

1

NITRIC ACID HNO3

1

0

0

0

0

1

1

0

0

0

NITRIC ACID Temperature, C 180 °

160

Ti

140 120 100 80

18-10 17-12-2.5

60

13% Cr-steel

40 20

0

20

40

60

80 100 HNO3, weight-%

Isocorrosion diagram, 0.1 mm/year, in nitric acid. Broken-line curve represents the boiling point.

II:35

N NITRIC ACID

NITRIC ACID + ACETIC ACID

NITRIC ACID + ADIPIC ACID

red, fuming (density = 1.615) 72.7 % HNO3 + 26.4 % N 2O4 + 0.9 % H2O Temp.°C 25 40

Conc. HNO3, % Conc. CH3COOH, % Temp.°C

10-40 20 20

45 % HNO3 + 20 % HOOC(CH2)4COOH



2 2 0 0 0 0 0 0 0 0 0 0 0 0 0


0 1

1 1

2

2

Temp.°C

NITRIC ACID + ALUMINIUM NITRATE + POTASSIUM NITRATE Conc. HNO3, % Conc. Al (NO3)3, % Conc. KNO3, % Temp.°C


15 0 satd. 90

15 30 13 90

60 0 satd. 70

65-67 15-20 8-11 60

88 10 0 BP

0 0 0 0 0

0 0 0 0 0

0 0 0 0 0

0 0 0 0 0

1 1 1 1 1

1 1 1 1 1

0

0

0

0

0

0

0

5 % HNO3 + 7 % C2H5OH + 65 % H2SO4 Temp.°C

130


2 2 2 2 2 2 2 2

2

0

NITRIC ACID + AMMONIUM SULPHATE

88 0 10 BP

0 0 0 0 0

NITRIC ACID + ETHYL ALCOHOL + SULPHURIC ACID

II:36

60 9-30 1 70

100

26 % HNO3 + 30 % (NH4)2SO4 Temp.°C 80


NITRIC ACID + HYDROCHLORIC ACID Conc. HNO3, % Conc. HCl, % Temp.°C

9 18 90

17 28 20


2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

1

0

0 0 0 0 0 0 0 0 0 0 0 0

N NITRIC ACID + HYDROFLUORIC ACID

Conc. HNO3, % Conc. HF, % Temp.°C

1.5 0.5 80

10 3 70


2 2 2 2 2 2 2 1

2 2 2 2 2 2 2 2 2

2

15 4 40

2

NITRIC ACID + IRON (III) CHLORIDE 15 4 50

2

15 4 60

2

2

2

2

2 2

2 2

2 2

2

NITRIC ACID + OXALIC ACID

20 4 25

2 2 2 2 2 2 2 1

30 0.1 BP

Conc. HNO3, % Conc. FeCl3, % Temp.°C

10 6 20

2

2 2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

2 2 1p 1p 0p 0p 0p 0p

2

2


1 0 2 1 1

NITRIC ACID + POTASSIUM NITRATE

50 20 70

Conc. HNO3, % Conc. KNO3, % Temp.°C


2 1 0 0 0 0 0 0


NITRIC ACID + SODIUM FLUORIDE

20 4 65

1

1 0 2 1 0 2

Conc. HNO3, %% Conc. (COOH)2, % Temp.°C

0

20 4 30

0

NITRIC ACID + SODIUM CHLORIDE

15 saturated 90

0 0 0 0 0 0

Conc. HNO3, % Conc. NaCl, % Temp.°C

55 1 80


1ps 1ps 1ps 1ps 1ps 0 1 1 0 1 1 0

NITRIC ACID + SULPHURIC ACID cont.

Conc. HNO3, % Conc. NaF, % Temp.°C

10 1 60

Conc. HNO3, % 1 Conc. H2SO4, % 5 Temp.°C 25


2 2 2 2 2 2 1 1


2

1 5 50

1 10 25

1 10 80

1 17 100

1 95 50

1 99 35

3 10 25

3 10 80

3 50 25

0 0 0 0 0

0 0 0 0 0

0 0 0 0 0

1 0 0 0 0

1

1 0 0 0 0

0 0 0 0 0

0 0 0 0 0

1 0 0 0 0

0 0 0 0 0

0

1

1

2

2

1

0

1

0

II:37

N NITRIC ACID + SULPHURIC ACID cont. Conc. HNO3, % 5 Conc. H2SO4, % 20 Temp °C 25


0 0 0 0 0

0

5 20 50

5 60 25

0 0 0 0 0

5 60 50

0 0 0 0 0

0

5 60 80

0 0 0 0 0

0

7 17 100

0 1 1 1 1

0

2

10 60 60

10 60 80

2 2

2 2

0 0 0 0 0 0

1 1 1 1 1 0

0 0 0 1

0 0 0 2

10 80 50

10 90 35

0 0 0 0 0

0 0 0 0 0

1

2

13 16 100

0

20 80 20

20 80 60

20 80 100

25 15 100

30 20 80

0 0 0 0 0 0

1 1 1 0 0 0 0

1 1 1 1 1

0

1 0 0 0 0

2

2

NITRIC ACID + SULPHURIC ACID

Conc. HNO3, % Conc. H2SO4, % Temp.°C

30 40 80


1 1 1 1 1 0

0 0 0 1

30 70 35

0 0 0 0 0

1

47 14 100

0

50 20 80

1 1 1 1 0 0 0 0 0 0 1

50 50 60

2 1 1 1 1 0 0 0

NITROUS ACID

pure

HNO2 20

Conc. % Temp.°C


II:38

0 0 0 0 0 0 0 0 0 0 0 0 0 0

0

54 67 BP

2

0

NITROCELLULOSE

Temp.°C

54 67 75


all conc. 20

2 2 0 0 0 0 0 0

0

54 95 60

1

56 14 100

0

65 35 35

90 10 35

0 0 0 0 0 0

0 0 0 0 0

0

0

1

O OXALIC ACID cont.

(COOH)2 Conc. % Temp. °C

0.5 20

0.5 35

0.5 60

0.5 80

0.5 100 =BP

1 35

1 60

1 100 =BP

2.5 20

2.5 40

2.5 60

2.5 80

2.5 100 =BP

5 20

5 35

5 60


1 1 0 0 0 0 0 0 0 0 0 0 0 0 0

1 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0 0 0 0 0 0 0 2

2 2 1 1 0 0 0 0 0 0 0 0 0 0 2

2 2 2 2 2 1 1 0 1 1 0 1 1 0 2

2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 2

2 2 2 2 2 1 1 0 1 1 0 1 1 1 2

1 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 2

2 2 1 1 0 0 0 0 0 0 0 0 0 0 2

2 2 2 2 2 1 1 0 1 1 1 2 1 1 2

1 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 1

2 2 0 1 0 0 0 0 0 0 0 0 0 0 2

Conc. % Temp. °C

5 85

5 100 =BP

10 25

10 50

10 60

10 80

10 101 =BP

25 60

25 75

25 103 =BP

40 75

40 106 =BP

50 107 =BP


2 2 1 1 1 0 0 0 0 0 0 0 0 0 2

2 2 2 2 1 1 1 1 1 1 1 2 1 1 2

2 2 0 0 0 0 0 0 0 0 0 0 0 0 1

2 2 0 0 0 0 0 0 0 0 0 0 0 0 2

2 2 1 1 0 0 0 0 0 0 0 0 0 0 2

2 2 2 2 1 1 0 0 0 0 0 1 0 0 2

2 2 2 2 2 1 1 1 1 1 1 2 2 1 2

2 2 2 2 0 0 0 0 0 0 0 0 0 0 2

2 2 2 2 1 1 0 0 0 0 0 1 0 0 2

2 2 2 2 2 2 2 1 1 1 1 2 2 2 2

2 2 2 2 1 1 0 0 0 0 0 1 0 0 2

2 2 2 2 2 2 2 1 1 1 1 2 2 2 2

2 2 2 2 2 2 2 1 1 1 1 1 2 2 2

OXALIC ACID (COOH)2

OXALIC ACID Temperature, C 120 °

100 904L 80 17-14-4 60 17-12-2.5 40

20

18-2 18-10

Ti

0

20

40

60

80 100 (COOH)2, weight-%

Isocorrosion diagram, 0.1 mm/year, in oxalic acid. Broken-line curve represents the boiling point and chain line curve represents solubility.

II:39

O, P OXALIC ACID + NITRIC AND SULPHURIC ACIDS

PARAFFIN

2 % (COOH)2 + x % HNO3 + 5 % H2SO4 Conc. HNO3, % 0 0.5 1 Temp. °C 60 60 60

Temp. °C



2 2 2

0 0 0 0

0 0 0 0

PERCHLORIC ACID

PECTIN

20-100

Temp. °C

20-100

0 0 0 0 0 0 0 0 0 0 0 0 0 0


0 0 0 0 0 0 0 0 0 0 0 0 0

PETROL

PHENOL

HClO4

C6H5OH

Conc. % Temp. °C

10 20


Temp. °C

100 20

2 2 2 2 2 2 1 1

2 2 2 2 2 2 2 2


0

0

Conc. %

20BP

0 0 0 0 0 0 0 0 0 0 0 0 0 0

Temp. °C

all conc. 50

70100 BP


0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 1 0 0 0 0 0 0 0 0 0 0 0

PHOSPHORIC ACID H3PO4

cont.

Conc. % Temp. °C

1 20

1 100 =BP

1 140

3 100 =BP

5 2060

5 85

5 100 =BP

10 40

10 60

10 80

10 101 =BP

20 35

20 60

20 102 =BP

30 30 20- 60 35


2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0

2 1 0 0 0 0 0 0

2 2 0 0 0 0 0 0

2 0 0 0 0 0 0 0

2 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0

2 2 0 0 0 0 0 0

2 2 0 0 0 0 0 0

2 2 0 0 0 0 0 0

2 2 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 1

2 2 0 0 0 0 0 0 0 0 0 0 0 0 2

2 2 0 0 0 0 0 0

2 2 0 0 0 0 0 0

0

0

0

1

II:40

0

0

1

0 0

0 1

0 2

0 0

0 1

0 2

0 2

P PHOSPHORIC ACID H3PO4

cont.

Conc. % Temp. °C

30 100

40 35

40 50

40 100

40 106 =BP

50 20

50 35

50 50

50 85

50 100

50 110 =BP

60 20

60 35

60 100

60 116 =BP

70 35


2 2 1 1 0 0 0 0

2 2 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0

2 2 1 1 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0

2 2 1 0 0 0 0 0 0 0

2 2 2 1 1 1 0 0 0 0

2 2 0 0 0 0 0 0

2 2 0 0 0 0 0 0

2 2 2 2 1 1 1 0

0

0

0 0 0 0

0 0 0 1

0 0 0 2

0 0 0 2

0 0 0 2

0 0

0 0

0 0

1

1

2

2 2 2 2 2 2 2 1 1 1 0 2 1 1 2

2 2 0 0 0 0 0 0

0

2 2 2 2 2 1 1 1 1 0 1 1 0 0 2

86 85

86 95

86 105

86 115

0 0 1

0 0 2

0 0 2

2 2 2 2 1 1 0 1 0 1 0 1 0 0 2

Conc. % Temp. °C

70 90

70 126 =BP

80 20

80 35

80 80

80 100

80 146 =BP

86 20

86 50


2 2 2 2 1 0 0 0 0 0 0 0 0 0 2

2 2 2 2 2 2 2 1 1 1 1 2 1 2 2

2 2 0 0 0 0 0 0

2 2 0 0 0 0 0 0

2 2 2 1 0 0 0 0

2 2 1 0 0 0 0 0

0 0 0

0 0 0

2 2 2 2 2 2 2 2 1 1 1 2 2 2 2

2 2 0 0 0 0 0 0

0 0 0

2 2 2 2 1 1 1 1 1 0 0 0 1 0 2

0 0

0 0

0 0

0 0 2

0 0 2

0 0

0

2

0

2

PHOSPHORIC ACID H3PO4

2

2

2

1

PHOSPHORIC ACID

2 2 2 2 1 1 1 0 0 1 1 1 1 2

0

1

1

1

1 1

86 156 =BP

2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

PHOSPHORIC ACID

Temperature, C 140

Temperature, C 140

120

120

°

°

904L 100

100 17-14-4

80

18-10

17-12-2.5

80

17-12-2.5 60

60 18-2

40 20

0

20

40

60

80 100 H3PO4, weight-%

Isocorrosion diagram, 0.1 mm/year, for stainless steels in phosphoric acid of chemical purity. Broken-line curve represents the boiling point.

Ti

40 20

0

20

40

60


Isocorrosion diagram, 0.1 mm/year, for titanium and steel 17-12-2.5 in phosphoric acid of chemical purity. Broken-line curve represents the boiling point.

II:41

P PHOSPHORIC ACID WITH CHLORIDES

PHOSPHORIC ACID WITH FLUORIDES mm/year 1,0

mm/year 10 5

17-12-2.5

100°C

17-12-2.5

0,8

1 0.5

80 C °

0,6 0.1 0.05

60 C °

0,4

50°C

0.01 0.005

40 C °

20 C °

0,2

0.001 1

2

5

10

20

50

100 200

0,0 0,0

500 1000 Cl-, ppm

0,5

1,0

1,5

2,0

2,5

3,0

F-, %

Corrosion rate, mm/year, for steel 17-12-2.5 in 76% phosphoric acid with fluoride additions.

Corrosion rate, mm/year, for steel 17-12-2.5 in 76% phosphoric acid with choride additions.

PHOSPHORIC ACID, WET-PROCESS ACID From a corrosion point of view, wet-process phosphoric acid (WPA) is a rather complicated chemical. The reason is that it usually contains large amounts of impurities, some of which are activating and others will inhibit the corrosion process. The most detrimental impurities are hydrochloric and hydrofluoric and sulphuric acids, while ferric and aluminium ions are beneficial. The following four tables present corrosion test results performed in two series of synthetic wet process acids. In one of the series the detrimental impurities chloride and fluoride have been varied, while the content of the others, iron, aluminium and sulphuric acid, have been kept constant. In the other series the content of iron and aluminium was varied and all the others kept constant. The test acids also contained other compounds in constant quantities. These were: 54% P2O5, 0.1% SiO2, 0.2% CaO and 0.7% MgO. Due to the rather complex nature of WPA corrosion, the data presented must be regarded as examples only. In critical applications it would therefore be well advised to get additional information from corrosion expertise. The necessary data to determine the risk for corrosion are the composition of the acid and the maximum operation temperature.

PHOSPHORIC ACID. Synthetic WPA acid Constant concentrations: 1.0% Fe2O3, 1.0% Al2O3, 4.0% H2SO4 Conc. HF, % Conc. HCl, ppm Temp. °C


II:42

0.2 200 35

0.2 200 50

0.2 200 85

0 0

0 0

0

0

0

0

0

0

0

0

0.2 600 35

0.2 600 50

0 0

0

0.2 600 85

cont. 0.2 1000 35

0.2 1000 50

0.2 1000 85

2

0

0

0

0

0 2 0 0

2

0.6 200 35

0.6 200 50

0.6 200 85

0 0

0 0

0

0

0

0

0

0

0

0

0.6 600 35

0.6 600 50

2 0

0

0

0

0

2 0 0

0

P PHOSPHORIC ACID. Synthetic WPA acid Constant concentrations: 1.0% Fe2O3, 1.0% Al2O3, 4.0% H2SO4 Conc. HF, % Conc. HCl, ppm Temp. °C


0.6 600 85

0.6 1000 35

0.6 1000 50

2 0

2 2

2

0.6 1000 85

1.0 200 35

1.0 200 50

0 0

0 0

2 2

0

0

0

2 2 2

cont. 1.0 200 85

1.0 600 35

1.0 600 50

2 0

2

2 0

0

0

0

0

1.0 600 85

1.0 1000 35

1.0 1000 50

2 0

2 2

2 0

0

0

0

1.0 1000 85

2 2

0

2

2 2 2

PHOSPHORIC ACID. Synthetic WPA acid Constant concentrations: 600ppm HCl, 1.1% HF, 4.0% H2SO4 Conc. Fe2O3, % Conc. Al2O3, % Temp. °C

0.2 0.2 35

0.2 0.2 50


0.2 0.2 85

0.2 0.6 35

0.2 0.6 50

0.2 0.6 85

2 2 2

0

2 2 2

2

2 2 2

2

cont. 0.2 1.0 35

0.2 1.0 50

0.2 1.0 85

0.6 0.2 35

0.6 0.2 50

0.6 0.2 85

0.6 0.6 35

0.6 0.6 50

2 2 2

1

2 2 2

0 0

0 0

2

2 2 0

2

2 2 0

PHOSPHORIC ACID. Synthetic WPA acid Constant concentrations: 600ppm HCl, 1.1% HF, 4.0% H2SO4 Conc. Fe2O3, % Conc. Al2O3, % Temp. °C


0.6 0.6 85

0.6 1.0 35

0.6 1.0 50

0.6 1.0 85

1.0 0.2 35

1.0 0.2 50

1.0 0.2 85

1.0 0.6 35

1.0 0.6 50

1.0 0.6 85

1.0 1.0 35

1.0 1.0 50

1.0 1.0 85

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

2 2 2

2 2 2

2

2

2 2 2

II:43

P PHOSPHORIC ACID + AMMONIUM NITRATE

PHOSPHORIC ACID + AMMONIUM NITRATE + AMMONIUM SULPHATE + NITRIC ACID, 4 % H 3PO4 + 15 % NH4NO3 + 9 % (NH4)2SO4 + 9 % HNO3

Conc. H3PO4, % Conc. NH4NO3, % Temp. °C

10 30 80

Temp. °C


2 1 0 0 0 0 0 0 0 0 0 0 0 0 2


100

0 0 0 0 0 0 0 0 0 0 0 0

PHOSPHORIC ACID + AMMONIUM SULPHATE + SULPHURIC ACID Conc. H3PO4, % Conc.(NH4)2SO4, % Conc. H2SO4, % Temp. °C


10 25 1.5 90

15 25 1 100

15 25 3 100

15 30 3 90

15 20 20 20

16 9 1 80

0 0 0 0 0

2 0 0 0 0 0

2 0 0 0 0 0

2 0 0 0 0 0

2 0 0 0 0 0

0 0 0 0 0 0

0 0 0

0 0 0

0 0 0

0 0 0

0 0 0

0 0 0

PHOSPHORIC ACID + CHROMIC ACID + SULPHURIC ACID

PHOSPHORIC ACID + CHROMIC ACID

57 % H3PO4 + 9 % CrO3 + 14 % H2SO4 Temp. °C 80

80 % H3PO4 + 10 % CrO3 Temp. °C 20



II:44

2 2 2 2

2 2 2

60

0 0 0 0 0 0

2 2 2 2 1 0

0 0 0 0

1 1 0 0

PHOSPHORIC ACID + CALCIUM SULPHATE + SULPHURIC ACID Conc. H3PO4, % Conc. CaSO4, % Conc. H2SO4, % Temp. °C

4 50 2 50

22 Traces 1 70


2 2

2 2

1 0 0 0 0 0

1 0 0 0 0

1 0 0 1

2

PHOSPHORIC ACID + FLUOSILICIC ACID + SULPHURIC ACID Conc. H3PO4, % Conc. H2SiF6, % Conc. H2SO4, % Temp. °C

30 1 3 70

55 1 1 90


2 2 2 2 0 0 0 0 0

2 2 2 2 1 1 1 1 1 1 0 2 1 1 2

1 0 0 2

P PHOSPHORIC ACID + HYDROFLUORIC ACID cont. Conc. H3PO4, % Conc. HF, % Temp. °C

1.5 1 50

41.4 0.5 20

41.4 0.5 40

41.4 0.5 60

41.4 1 20

41.4 1 40

41.4 1 60

41.4 2.5 20-

41.4 2.5 60

76 0.5 20 40

76 0.5 40

76 0.5 60

76 0.5 80

76 1 20

76 1 40


2 2 2 2 2 2 1 1 0 0 0 1 1 0 2

2 2 1 1 0 0 0 0

2 2 2 2 1 1 0 0

2 2 2 2 1 1 1 0

2 2 2 2 1 1 0 0

2 2 2 2 1 1 1 0

2 2 2 2 1 1 1 0

2 2 1 1 0 0 0 0

2 2 2 2 1 0 0 0

2 2 2 2 0 0 0 0

2

1

2

2

2

2

2 2 2 2 1 1 1 1 0 1 0 1 1 1 2

2 2 1 1 0 0 0 0

1

2 2 2 2 2 1 1 1 1 1 1 2 2 2 2

2 2 1 1 0 0 0 0

1

2 2 2 2 2 1 1 1 0 1 0 2 1p 1 2

2

2

2

PHOSPHORIC ACID + HYDROFLUORIC ACID

PHOSPHORIC ACID + HYDROFLUORIC ACID + NITRIC ACID

Conc. H3PO4, % Conc. HF, % Temp. °C

76 1 60

76 1 80

76 2 20

76 2.5 20

80 1 120

Conc. H3PO4, % Conc. HF, % Conc. HNO3, % Temp. °C

18 0.2 28 65

19.3 0.1 31.2 65

19.3 0.1 31.2 90


2 2 2 2 1 1 1 0

2 2 2 2 1 1 1 1 0 1 1 2 1 1 2

2 2 2 2 0 0 0 0

2 2 2 2 1 0 0 0

2 2 2 2 2 2 2 2 1 2 2 2 2 2 2


2 2 2 2 1 1 1 1 0 1 0 1 1 0 1

2 2 2 2 0 0 0 0 0

2 2 2 2 1 1 1 1 1 1 1 1 1 1 2

2

2

2

0 0 0 1

PHOSPHORIC ACID + HYDROFLUORIC ACID + NITRIC ACID + SULPHURIC ACID 7.9 % H3PO4 + 0.1 % HF + 12 % HNO 3 + 25.8 % H 2SO4 Temp. °C

90


2 2 2 2 1 1 1 1

2

II:45

P PHOSPHORIC ACID + SODIUM CHLORIDE

PHOSPHORIC ACID + NITRIC ACID + SULPHURIC ACID Conc. H3PO4, % Conc. HNO3, % Conc. H2SO4, % Temp. °C

43 2 45 100


43 2.2 45 105

1 1 1

64 1.9 23 90

0 0 0 0 0

1 1 1 1 0

66 7.2 10.5 100

78 3 18 95

1 1 1 1 0 0 0

Conc. H3PO4, % 76 Conc. NaCl, ppm 6.2 Temp. °C 40


1 1 1 1 0

PHOSPHORIC ACID + SULPHURIC ACID

76 6.2 80

76 312 40

76 312 80

2

2

2

2

0

1

0

1

PHOSPHORIC ANHYDRIDE phosphorus pentoxide, P2O5

Conc. H3PO4, % Conc. H2SO4, %

40 2

41.4 2

41.4 3.5

43 47

53 15

76 3.5

Temp. °C

BP

80

80

70

60

80


2 2 2 2 2 2 2 2 0 1 0

2 2 2 2 0 0 0 0 0

2 2 2 2 1 0 0 0 0

2 2 2 2 1 1 1 1 1 1 1

2 2 2 2 2 2 2 1 0 0 1

2 2 2 2 1 0 0 0 0

2

2

2

2

2

2

PHOSPHORUS PENTACHLORIDE

PICRIC ACID

PCl5

trinitrophenol, C6H2(NO2)3OH

Conc. % Temp. °C


Dry 20

Moist 20

0 0 0 0 0

1 0 0 0 0

0

1

POTASSIUM K

Conc. % Temp. °C

100 20

Conc. % Temp. °C

1 BP

All conc. 20

Conc. % Temp. °C

Molten 540-600


0 0 0 0 0 0 0 0 0 0 0 0 0 0


2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0


0 0 0 0 0 0 0 0 0 0 0 0

II:46

Risk of pitting corrosion in presence of moisture.

P POTASSIUM ACETATE

POTASSIUM ACETATE + SODIUM ACETATE

KOOCCH3 Conc. % Temp. °C

All conc. 100


0 0 0 0 0 0 0 0 0 0 0 0 0 0

Molten

70 % KOOCCH3 + 30 % NaOOCCH 3 Temp. °C

292

2

300


0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0

POTASSIUM BICARBONATE KHCO3 Conc. % Temp. °C

All conc. 100


0 0 0 0 0 0 0 0 0 0 0 0 0 0

POTASSIUM BISULPHATE

POTASSIUM BISULPHITE

KHSO4

KHSO3

Conc. % Temp. °C

2 90

5 20

5 50

5 90

10 20

10 90

10 100

15 90

Conc. % Temp. °C

10 20

10 BP


2 2

2 2

2 2

2 2

2 2

2 2

2 2

2 2

2 0 0 0 0

1 0 0 0 0 0 0 0 0 0 0 0

1 0 0 0 0 0 0 0 0 0 0 1

2 1 1 1 0 0 0 0 0 0 0 2

1 0 0 0 0

2 1 1 1 1 0

0 0

0 2

2 2 2 2 1 0 0 0 0 0 0 2

2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0

0

2 2 1 1 1 1 1 1 1 1 1 2


2

POTASSIUM BITARTRATE

POTASSIUM BROMIDE

KH(OOC(OH)CH)2

KBr

0

POTASSIUM BROMIDE + POTASSIUM HEXACYANOFERRATE (III)

Conc. % Temp. °C

Saturated at 100°C BP

Conc. % Temp. °C

All conc. 20

2.3 % KBr + 1.5 % K 3Fe(CN)6


2 2


2 2 0p 0p 0p 0p 0p 0p


1 0 0 0 0

0

0

If air is present, attacks by sulphurous and sulphuric acid can occur in the gaseous phase

Temp. °C

20

0p 0p 0p 0p 0p 0p

0

II:47

P POTASSIUM CARBONATE

POTASSIUM CHLORATE

K2CO3

KClO3

Conc. % Temp. °C


All conc. BP

Molten 900-1000

2 2 2 2 2 2 2 2

0 0 0 0 0 0 0 0 0 0 0 0 0 0

KCrO4 All conc. BP


10

36

Temp. °C

710 50

100

BP


2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0

1 0 0 0 0

POTASSIUM CYANIDE KCN

chrome alum, KCr(SO4)2 x 12H2O Conc. % 6 20 Temp. °C 20-90 BP


0 0 0 0 0 0 0 0 0 0 0 0

POTASSIUM DICHROMATE

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2

2 0 0 0 0

2 1 0 0 0

0

1

Conc. % Temp. °C

20 90

25 20

25 BP

Conc. % Temp. °C

All conc. 20

BP


0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0


2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 0 0 0 0 0 0 0 0 0 0 0 0 0

II:48

40 BP

2 2

POTASSIUM HEXACYANOFERRATE (II), K4Fe(CN)6

K2Cr2O7

Risk of pitting and stress corrosion cracking of stainless steels in presence of chlorides.

0

POTASSIUM CHROMIUM SULPHATE

POTASSIUM CHROMATE

Conc. % Temp. °C

Conc. %

Conc. % Temp. °C

All conc. 20

BP


2 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0

P POTASSIUM HEXACYANOFERRATE (III), K3Fe(CN)6 Conc. % Temp. °C


POTASSIUM HYDROXIDE KOH

All conc. 20

BP

Conc. % Temp. °C

0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0


10 BP

0 0 0 0 0 0 0 0 0 0 0 0 0 0

20 20

0 0 0 0 0 0 0 0 0 0 0 0 0 0

25 BP

2 0 0 0 0 0 0 0 0 0 0 0 0 1

50 20

1 0 0 0 0 0 0 0 0 0 0 0 0 0

50 BP

70 120

Molten 300-365

2 1 1s 1s 1s 1s 1s

2 1 1s 1s 1s 1s 1s

2 2 2 2 2 2 2 2

2

2

2

POTASSIUM HYPOCHLORITE

POTASSIUM IODIDE

POTASSIUM NITRATE

KClO

KI

KNO3

Conc. % Temp. °C


<2 20

>2 20

1p 0p 0p 0p 0p

2 1p 0p 0p 0p

0

0

Conc. % Temp. °C

All conc. BP


2 0p 0p 0p 0p 0p 0p

0

Conc. % Temp. °C

All conc. 20-BP

Molten 550 780


0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 0 0 0 0 0

POTASSIUM OXALATE

POTASSIUM PERMANGANATE

POTASSIUM PEROXIDE

(COOK)2 x H2O

KMnO4

K2O2

Temp. °C

20

BP

Conc. % Temp. °C

5-10 20

10 BP

Conc. % Temp. °C

10 20-90


2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0


0 0 0 0 0 0 0 0 0 0 0 0 0 0

1 0 0 0 0 0 0 0 0 0 0 0 0 0


0 0 0 0 0 0 0 0 0 0 0 2

1 1 1

II:49

P, Q POTASSIUM PERSULPHATE

POTASSIUM SULPHATE

POTASSIUM SULPHIDE

K2S2O8

K2SO4

K2S

Conc. % Temp. °C

4 20

Saturated 20

Conc. % Temp. °C


2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2


2 1 0 0 0

1

All conc. BP

Conc. % Temp. °C

1 20

0 0 0 0 0 0 0 0 0 0 0 0 0

Carbon steel 13% Cr-steel 18-2 th18-10 17-12-2.5 18-13-3 17-14-4 904L Sanicro 28 254 SMO 654 SMO SAF 2304 2205 SAF 2507 Ti

2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

PROPYLENE DICHLORIDE

PYRIDINE

PYROGALLIC ACID, pyrogallol,

CH2ClCHClCH3

C5H5N

trihydroxybenzene, C6H3(OH)3

Conc. % Temp. °C


100 20

0 0 0 0 0 0 0 0 0 0 0 0

Temp. °C

Risk of pitting corrosion in presence of moisture.

QUININE BISULPHATE


100

0 0 0 0 0 0 0 0 0 0 0 0 0

QUININE SOLUTION

Conc. % Temp. °C

All conc. 20-BP


2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

QUININE SULPHATE

(ammoniacal) Conc. % Temp. °C

All conc. 20

Temp. °C

20

Conc. % Temp. °C

All conc. 20


2 2


2


2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

II:50

2 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0

Q, S QUINOSOL

SACCHARIN

SALICYLIC ACID

C9H6NOSO3K x H 2O

C6H4(OH)COOH

Conc. % Temp. °C


0.2-0.5 20

Conc. % Temp. °C

0 0 0 0 0 0 0 0 0 0 0 0


All conc. 100

Conc. % Temp. °C

0 0 0 0 0 0 0 0 0 0 0 0 0


SILVER BROMIDE

SILVER BROMIDE + SILVER IODIDE

AgBr

AgBr + AgI

Conc. % Temp. °C

All conc. 20-BP

Conc. AgBr, % Conc. AgI, % Temp. °C


2 0p


The risk of pitting is small since the salt has low solubility in water.

0p 0 0 0 0 0 0 0 0 0 0 0

5 2085

0 0 0 0 0 0 0 0 0 0 0 0 0 0

All conc. 0.2 BP

see the first section of the handbook. 0ps 0 0 0 0 0 0 0 0 0 0 0

The risk of pitting and stress corrosion crakking is small, since the salts have low solubility in water.

SODIUM

SODIUM ACETATE

AgNO3

Na

NaOOCCH3

All conc. 20-BP

Molten 250

Conc. % Temp. °C


2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0


0 0 0 0 0 0 0 0 0 0 0 0

SEA WATER

SILVER NITRATE

Conc. % Temp. °C

20 100

Molten 600

0 0 0 0 0 0 0 0 0 0 0 0

800

Conc. % Temp. °C

All conc. 20-340

0 0 0 0 0 0 0 0 0 0 0 1


0 0 0 0 0 0 0 0 0 0 0 0 0 0

II:51

S SODIUM ALUMINATE

SODIUM BICARBONATE

NaAlO2

NaHCO3

Conc. % Temp. °C


All conc. 20

Conc. % Temp. °C

All conc. 20-100

0 0 0 0 0 0 0 0 0 0 0 0 0


0 0 0 0 0 0 0 0 0 0 0 0 0 0

SODIUM BISULPHATE NaHSO4 Conc. % Temp. °C

1 85


2 20

2 85

4 20

2 2 1 0 0 0 0

0 0 0 0 0 0 0

1 0 0 0 0 0 0

0 0 0

0 0 0

1 0 0 0 0

0

4 BP

5 20

5 85

10 20

10 50

10 BP

15 85

2 2

2 2

2 2

2 2

2 2

2 2

2

2 1 1 1 0 1 1 0 1 1 0

1 0 0 0 0 0 0

2 0 0 0 0 0 0

1 0 0 0 0

2 0 0 0 0

2 2 2 2

0 0 0

0 0 0

1 1

2 2 2 1 0 0 0

2 1 1

0 0 0

SODIUM BISULPHITE

SODIUM BROMIDE

SODIUM CARBONATE

NaHSO3

NaBr

Na2CO3

Conc. % Temp. °C

10 20

10 BP

Conc. % Temp. °C

5-10 20


2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 0


2

II:52


0p 0p 0p 0p 0p 0p 0 0 0 0 0 0 0

20 80

0p 0ps 0ps 0ps 0ps 0ps 0 0 0 0 0 0 0

Conc. % Temp. °C


All conc. 20-BP

0 0 0 0 0 0 0 0 0 0 0 0 0 0

Molten 900

2 2 2 2 2 2 2

S SODIUM CHLORATE + SODIUM CHLORIDE, NaClO3 + NaCl

SODIUM CHLORATE NaClO3 Conc. % Temp. °C


1020 BP

0 0 0 0 0 0 0 0 0 0 0 0

30

30

20

BP

0 0 0 0 0 0 0 0 0 0 0 0

1 0 0 0 0


1 3 80

5-10 1-1.5 20

P 0ps 0ps 0ps 0ps 0ps

P 0p 0p 0p 0p 0p

1

0


0

SODIUM CHLORIDE + HYDROGEN PEROXIDE, NaCl + H2O2 Conc. NaCl, % Conc. H2O2, % Temp. °C

Conc. NaClO3, % Conc. NaCl, % Temp. °C


30 5 BP

35 satd. BP

70 satd. 120

1p P 1ps 0ps 0ps 0ps 0ps 0 0 0 0 0 0 0

2 2 P 2 0ps 0ps 0ps 0ps 0P 0P 0P 0P 0P 0P 0

2 2 P 1ps 0ps 0ps 0ps 0ps 0 0 0 1P 1P 0 0

SODIUM CHLORITE

SODIUM CITRATE

NaClO2

C3H4(OH)(COONa)3

Conc. % Temp. °C


5 20

5 BP

P 2 2 1 1 0

2 2 2 2 1

0

0

Risk of pitting and stress corro sion cracking of stainless steels in presence of chlorides.

Conc. % Temp. °C

3.5 20100

35 100


2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

SODIUM CYANIDE

SODIUM DICHROMATE

SODIUM DITHIONITE

NaCN

Na2Cr2O7 x 2H2O

Na2S2O4

Conc. % Temp. °C


All conc. BP

Conc. % Temp. °C

0 0 0 0 0 0 0 0 0 0 0 0 0 0


Saturated 50

Conc. % Temp. °C

2 70

0 0 0 0 0 0 0 0 0 0 0 0 0

Carbon steel 13% Cr-steel 18-2 18-10 0p, particularly in the 17-12-2.5 0 gaseous phase 18-13-3 0 17-14-4 0 904L 0 Sanicro 28 0 254 SMO 0 654 SMO 0 SAF 2304 0 2205 0 SAF 2507 0 Ti 0

II:53

S SODIUM FLUORIDE

SODIUM HYDROXIDE

NaF

NaOH

Conc. % Temp. °C


cont.

5-10 20–100

Conc. % Temp. °C

10 20

0 0 0 0 0 0 0 0 0 0 0 0 0 2


0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

10 90

10 103 =BP

0 0 0 0 0 0 0

1 0 0 0 0 0 0

20 20

20 90

25 20

25 112 =BP

30 116 =BP

40 80

40 90

1 0 0 0 0 0 0 0 0

2 1 1s 0s 0s 0s 0s 0ND 0ND

1 0 0 0 0 0 0 0

1 0 0 0 0 0 0 0

0 0 0 1

0ND 0ND 0ND 1

0

0

1

1

0

60 90

60 120

60 160 =BP

70 90

70 130

70 180 =BP

90 300

Molten 320

1 1 1 1 1 0 0 0

2 2 1 1 1 1 1 0 0

2 2 2 2 2 2 2 2 2 2

1 1 1 1 1 1 0 0

2 2 1 1 1 1 1 0

2 2 2 2 2 2 2 2 2 2

2 2 2 2 1s 1s 1s 1s

2 2 2 2 2 2 2 2

2 2 2 2

0

1

0

1

2

2

1 0 0 0 0 0 0 0

0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

30 100

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

30 20

2 0 0 0 0 0 0

1

SODIUM HYDROXIDE NaOH Conc. % Temp. °C


40 100

40 128 =BP

50 60

50 90

50 100

50 120

50 140 =BP

1 1 1 1 1 0 0 0

2 2 1s 1s 1s 1s 1s 0ND 1ND

1 0 0 0 0 0 0

1 1 1 1 1 0 0

2 1 1 1 1 0 0

2 2 1 1 1 1 0 0

0

1

2 2 2 1s 1s 1s 1s 1s 1ND 1ND

1ND 2 1ND 1

0

0 1

1

0

1

1

1

2 2 2 1

1

1

0

0

1

2 2

SODIUM HYDROXIDE Temperature, C 180 °

904L 160

Risk of SCC

140

Ti

120

18-10 17-12-2.5

100 80 60 40 20

0

10

20

30

40

50

60

70

80 90 100 NaOH, weight-%

Isocorrosion diagram, 0.1 mm/year, in sodium hydroxide. Broken-line curve represents boiling point. Chain line curve represents solubility.

II:54

S SODIUM HYDROXIDE + SODIUM CHLORIDE

SODIUM HYDROXIDE + SODIUM SULPHIDE, NaOH + Na2S

NaOH + NaCl Conc. NaOH, % 1 Conc. NaCl, % 125 Temp. °C 50


0 0 0 0 0

0.5 16.5

5 20

5 40

BP

108

80

0s 0

0 0 0 0p 0 0

0

5 40 25 108

10 2020 108

20 10-

20 40

108

80

0 0 0 0 0 0 0

0 0 0 0 0 0 0

0 0 0 0 0 0 0

0 0 0 0 0 0 0

0 0 0 0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 1

0 0 0 1

0 0 0 0 0

0

40 120 80

40 120 108

60 2 100

0 0 0 0 0 0 0

1 1 1 0 0 0 0

1 1 1 1 0 0 0

0 1

1 1 0 1

1 1 0 1

Conc. NaOH, % Conc. Na2S, % Temp. °C

2.5 1 BP

65 10 165

0 0 0 0 0 0 0

2 2 2 2 2 2 2 1s

0

2

All conc. 20BP

Molten


SODIUM HYPOCHLORITE

SODIUM METABORATE

SODIUM NITRATE

NaClO

NaBO2

NaNO3

Conc. % Temp. °C

5 20

5 BP

Conc. % Temp. °C

Molten 100


2 2 1p 1p 1p 1p 0p 0p


0

0


0 0 0 0 0 0 0 0 0 0 0 0 0 0

Conc. % Temp. °C


2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0

SODIUM NITRITE

SODIUM OLEATE

SODIUM PERBORATE

NaNO2

NaOOCC17H33

NaBO3 x H2O2 x H2O

Conc. % Temp. °C

All conc. BP

Conc. % Temp. °C


0 0 0 0 0 0 0 0 0 0 0 0 0 0


360

All conc. 20

Conc. % Temp. °C

All conc. 20

2

0 0 0 0 0 0 0 0 0 0 0 0 0


0 0 0 0 0 0 0 0 0 0 0 0 1

II:55

S SODIUM PERCHLORATE

SODIUM PEROXIDE

SODIUM PHOSPHATE

NaClO4

Na2O2

Na3PO4

Conc. % Temp. °C

10 BP

Conc. % Temp. °C

10 20

10 100

Conc. % Temp. °C

All conc. BP


2 0 0 0 0 0 0 0 0 0 0 0 0 0


2 1 0 0 0 0 0 0 0 0 0 0 0 0 1

2 2 0 0 0 0 0 0 0 0 0 0 0 0 2


0 0 0 0 0 0 0 0 0 0 0 0 0 0


SODIUM PHOSPHATE + SODIUM HYDROXIDE, Na3PO4 + NaOH

SODIUM SALICYLATE

SODIUM SILICATE

NaOOC(OH)C6H4

Na2SiO3

Conc. Na3PO4, % Conc. NaOH, % Temp. °C

0.2 0.7 BP

1 5 80

Conc. % Temp. °C


0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 0 0 0 0 0 0 0 0 0 0 0 0 0 0


All conc. 20

Conc. % Temp. °C

All conc. 100

0 0 0 0 0 0 0 0 0 0 0 0 0 0


0 0 0 0 0 0 0 0 0 0 0 0 0 0

SODIUM SULPHATE

SODIUM SULPHIDE

SODIUM SULPHITE

Na2SO4

Na2S

Na2SO3

Conc. % Temp. °C

All conc. 20

Conc. % Temp. °C

5 BP

10 20

10-50 BP

Conc. % Temp. °C

50 20

50 BP


1 0 0 0 0 0 0 0 0 0 0 0 0 0 0


2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0


2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

II:56

S SODIUM THIOSULPHATE

SOFT SOAP

STANNIC (IV) CHLORIDE

Na2S2O3

solid or in solution

SnCl4

Conc. % Temp. °C

16-25 20-BP

Temp. °C

Conc. %

20

Temp. °C


2 0 0 0 0 0 0 0 0 0 0 0 0 0 0




2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

524 20

1824 BP

2 2 P 2 1p 1p 1p 1p

2 2 P 2 2 2 2 2

0

0

STANNOUS (II) CHLORIDE

STARCH

STARCH + HYDROCHLORIC ACID

SnCl2

pure

starch acidified with HCl

Conc. % Temp. °C

5 20

5 50

5 BP

Conc. % Temp. °C


2 2 P 1p 0p 0p 0p 0p

2 2 P 1p 0p 0p 0p 0p

2 2 P 2 0ps 0ps 0ps 0ps

0

0

0


STRONTIUM NITRATE

SULPHAMIC ACID

Sr (NO3)2

NH2SO3H

Conc. % Temp. °C


All conc. 60

Conc. % Temp. °C

31.5%, pH 1.9 150

0 0 0 0 0 0 0 0 0 0 0 0 0


2 2 2 2 2 2 2 1

0

cont.

All conc. 100

Conc. % Temp. °C

1 75

2

0 0 0 0 0 0 0 0 0 0 0 0 0


1 95

0 0 0 0 0

0

0 0

0 0

0 1

0

0

1 BP

1 1 1 1 1 1 0 1 1 0

2 50

2 75

2

2

0 0 0 0 0 0 0 0 0 0 0 0

1 1 0 0 0 0 0 0 0 0 0 1

2 95

1 1

2 BP

1

0 0

1

5 50

5 75

2

2

0 0 0 0 0 0 0 0 0 0 0 1

2 1 0 0 0 0 0 0 0 0 0 2

5 95

5 BP

2 1 2

0 0

1 1 1 0 1 1 1

II:57

S SULPHAMIC ACID

SULPHITE GAS

SULPHUR

NH2SO3H

digester gases containing SO2

S

Conc. % Temp. °C

10 60

10 75

Carbon steel 2 13% Cr-steel 18-2 18-10 1 17-12-2.5 0 18-13-3 0 17-14-4 0 904L 0 Sanicro 28 0 254 SMO 0 654 SMO 0 SAF 2304 0 2205 0 SAF 2507 0 Ti 1

10 95

10 20 BP 95

Temp. °C


2

2 1 1 1 0 0 0 0 0 0 0 2

2 2 2 2 1 1 1 1 2 1 1

0 0 0 0 0 0

1P 0 0 0 0 1 0

140150

2 2 1 0 0 0 0

0

SULPHUR CHLORIDE

SULPHUR DICHLORIDE

sulphur monochloride, S2Cl2

SCl2

Conc. %

Dry 100 136 =BP

Moist

Temp. °C

Dry 100 20


2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 1p 1p 1p 1p 1p 1p

20

2p

Conc. % Temp. °C

100 20

100 BP


2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

SULPHUR DIOXIDE SO2

Temp. °C


II:58

Dry gas 300

0 0

Liq. gas 25

Air-free, moist gas 20

100

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 1 1 0 0 0 0

2 2 1 1 0 0 0 0

0

0

Oxidation to sulphuric acid can occur in presence of air, resulting in general corrosion. See also Sulphurous acid.

Conc. % Vapour Temp. °C

Molten

Molten

240

445

570 =BP


2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2

2 2 2 2 2 2 2 2

2 1 1 1 1


S SULPHURIC ACID H2SO4

cont.

Conc, % Temp. °C

0.1 100 =BP

0.5 20

0.5 50

0.5 100

1 20 =BP

1 50

1 70

1 85

1 100

2 20

2 50

2 60 =BP

3 20

3 35

3 50


2 2 2 2 1 1 1 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 2 1 0 0 0 0 0 0 0 0 0 0 0

2 2 2 2 1 1 1 1 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 2 1 0 0 0 0 0 0 0 0 0 0 0

2 2 2 1 0 0 0 0 0 0 0 0 0 0 1

2 2 2 2 1 1 0 0 0 0 0 0 0 0 1

2 2 2 2 1 1 1 1 0 1 0 1

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 2 1 0 0 0 0 0 0 0 0 0 0 0

2 2 2 1 0 0 0 0 0 0 0 0 0 0 1

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 2 1 0 0 0 0 0 0 0 0 0 0 0

2 2 2 1 0 0 0 0 0 0 0 0 0 0 1

1

1

1 1

0 1

SULPHURIC ACID H2SO4

cont.

Conc, % Temp. °C

3 85

3 100 =BP

5 20

5 35

5 60

5 75

5 85

5 101 =BP

10 20

10 50

10 60

10 80

10 102 =BP

20 20

20 40


2 2 2 2 1 1 1 0

2 2 2 2 2 2 2 1 1 1 0 1 1 1 2

2 2 2 1 0 0 0 0 0 0 0 0 0 0 0

2 2 2 1 0 0 0 0 0 0 0 0 0 0 1

2 2 2 2 1 0 0 0 0 0 0 0 0 0 1

2 2 2 2 1 1 1 0 0 0 0 0 0 0 2

2 2 2 2 2 2 2 1 0 1 0 0 0

2 2 2 2 2 2 2 2 2 2 2 2 2

2 2 2 2 0 0 0 0 0 0

2 2 2 2 1 1 0 0 0 0

2

2

0 0 0 2

2 2 2 2 2 2 2 1 0 0 0 2 1 0 2

2 2 2 2 2 2 2 2 2 2

0 0 0 1

2 2 2 2 1 1 1 0 0 0 0 0 0 0 2

2 2 2 2 0 0 0 0 0 0 0 1 0 0 2

2 2 2 2 1 1 1 0 0 0 0 2 0 0 2

0

1

SULPHURIC ACID, deaerated

SULPHURIC ACID

Temperature, C 140

Temperature, C 140

120

120

100

100

°

2 2 2 2

°

SAF 2304

80

Sanicro 28

60

80 SAF 2507 2205

60

40

904L

40

904L

2205 Carbon Steel

Ti

20

0

20

40

60

80 100 H2SO4, weight-%

Isocorrosion diagram, 0.1 mm/year, in deaerated sulphuric acid of chemical purity. Broken-line curve represents the boiling point.

20

SAF 2507

0

20

40

60


Isocorrosion diagram, 0.1 mm/year, in naturally aerated sulphuric acid of chemical purity. Broken-line curve represents the boiling point.

II:59


cont.

Conc. % Temp. °C

20 50

20 60


2 2 2 2 1 1 1 0 0 0 0 2 0 0 2

2 2 2 2 2 1 1 0 0 0 0 2 1 0 2

20 80

20 100

30 20

30 40

30 60

1

2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

2 2 2 2 1 1 1 0 0 0

2 2 2 2 2 1 1 0 0 0

2 2 2 2 2 2 2 1 1 1

0 2 2 2 2

2 0

2 1 0 2

2

30 80

40 20

40 40

40 60

40 90

50 20

50 40

50 70

2 2 2 2 2 2 2 0 0

2 2 2 2 2 2 2 0 0 1 0 2 2 1 2

2 2 2 2 2 2 2 1 1

2 2 2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 0 0 0 0 2 2 1 2

2 2 2 2 2 2 2 0 0 1 0 2 2 1 2

2 2 2 2 2 2 2 2 1

2

2 2 1 2

2 2 2 2

0 2 2 0 2

0 2 2 2 2

2 2 2 2

2 2 2 2

SULPHURIC ACID WITH CHLORIDES

SULPHURIC ACID

Temperature, C 100

Temperature, C 140

°

°

904L

120 80

254SMO

100 60

80 654 SMO 18-10

17-12-2.5

60

254SMO

17-12-2.5

17-12-2.5

40

904L

904L

40

254 SMO

18 - 10

20

0

904L

20

40

60


20

0

20

40

60

80 100 H2SO4,weight-%

Isocorrosion diagram, 0.1 mm/year, for austenitic stainless steels in naturally aerated sulphuric acid of chemical purity. Broken-line curve represents the boiling point.

Isocorrosion diagram, 0.1 mm/year, in sulphuric acid with an addition of 200 ppm chlorides.

SULPHURIC ACID WITH CHLORIDES

SULPHURIC ACID WITH IRON SULPHATE


Temperature, C 120 0.02%Fe2(SO4)3 °

654 SMO

17-12-2.5

100

80

0.05%Fe2(SO4)3

SAF 2507 254 SMO

80

60 904L

60 17-12-2.5

40

654 SMO 0.05%FeSO4 904L

40

H2SO4

254 SMO 20

0

20

40

60


Isocorrosion diagram, 0.1 mm/year, in sulphuric acid with an addition of 2000 ppm chlorides.

II:60

20

0

10

20

30


Isocorrosion diagram, 0.1 mm/year, for steel 17-12-2.5 in sulphuric acid and in sulphuric acid with the given addition of iron sulphate. Broken-line curve represents the boiling point.


cont.

Conc. % Temp. °C

60 20

60 40

60 70

70 20

70 40

70 70

80 20

80 40

80 60

85 20

85 30

85 40

85 50

90 20

90 30


2 2 2 2 2 2 2 0 0 0 0 2 2

2 2 2 2 2 2 2 1 0 1 1

2 2 2 2 2 2 2 1 1

2 2 2 2 2 2 2 0 0 0 0

2 2 2 2 2 2 2 1 0 1 1

2 2 2 2 2 2 2 1 1

2 2 2 2 1 1 1 0

2 2 2 2 2 2 2 1 1 1

2 2 2 2 2 2 2 2 1 2

0 1 1 1 1 1 1 0 0 0

1 1 1 1 1 1 1 0 0

2 2 1 1 1 1 1 1 0

2 2 2 2 2 2 2 1 0

0 0 0 0 0 0 0 0 0 1 1

1 1 1 0 0 1 1 0 0

2

1

2

2

2

2

2 2 2

2 2 2

1 1 1 2

1

2

0

2 2 2

2 2

2

SULPHURIC ACID WITH CHROMIC ACID Temperature, C 120

1 2

2

2

SULPHURIC ACID WITH CHROMIC ACID Temperature, C 120

°

°

18-10 100

17-12-2.5 100

0.2-0.5% CrO3 2% CrO3

80

0.2-0.5% CrO3 2% CrO3

80

5% CrO3

5% CrO3

10% CrO3

10% CrO3

60

60 0% CrO3

0% CrO3 40

40 0% CrO3

0% CrO3 20

1 1 0 2

1 0 2

0

20

40

60


Isocorrosion diagram, 0.1 mm/year, for steel 18-10 in sulphuric acid and in sulphuric acid with the given additions of chromic acid. Broken-line curve represents the boiling point.

SULPHURIC ACID WITH COPPER SULPHATE Temperature, C 120 °

20

0

20

40

60

80

100

H2SO4, weight-%

Isocorrosion diagram, 0.1 mm/year, for steel 17-12-2.5 in sulphuric acid and in sulphuric acid with the given additions of chromic acid. Broken-line curve represents the boiling point.

SULPHURIC ACID WITH COPPER SULPHATE Temperature, C 120 °

17-12-2.5

Titanium

100

100 300 mg/I

80

80

200 mg/I

60

60

20

0 mg/I

100 mg/I

40

40

0 mg/I

0

20

200 mg/l

40

60


Isocorrosion diagram, 0.1 mm/year, for steel 17-12-2.5 in sulphuric acid and in sulphuric acid with the given additions of copper sulphate. Broken-line curve represents the boiling point.

20

0 mg/l

0

20

40

60


Isocorrosion diagram, 0.1 mm/year, for titanium in sulphuric acid and in sulphuric acid with the given additions of copper sulphate. Broken-line curve represents the boiling point.

II:61

S SULPHURIC ACID H2SO4 Conc. % Temp. °C

90 40

90 70

94 20

94 30

94 40

94 50

96 20

96 30

96 40

96 50

98 30

98 40

98 50

98 80


2 2 2 2 1 1 1 1 0 1 2 1 1 0 2

2 2 2 2 2 2 2 2 1

0 0 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0 0

2 2 2 1 0 1 1 1 0

2 2 2 1 1 1 1 1 0

0 0 0 0 0 0 0 0 0 1 0 1 0 0 2

1 1 0 0 0 0 0 0 0

2 2 1 0 0 1 1 1 0

2 2 2 1 1 1 1 1 1

1 1 0 0 0 0 0 0 0

1 1 1 0 0 0 0 1 0

0 0 2

0 0 2

2 2 2 2 0 1 1 1 0 0 1 0 1 0 2

2 2 2 2 2 2 2 2 1 2 1 1 1 1 2

2

2 0 0 2

2

0 2

0 2

1 2

1

2 0

0 0 2

1 0 2

1 2

SULPHURIC ACID fuming (OLEUM), H2SO4 + SO3 Conc. H2SO4 ,% Conc. SO3 , % Temp. °C

100 7 60

100 11 60

100 11 100

100 60 20

100 60 70

100 60 80


0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

2 2 1 0

0 0 0 0 0

0 0 0 0 0

0 0

2

2

2

2

2

2

2

SULPHURIC ACID + ACETIC ACID H2SO4 + CH3COOH Conc. H2SO4, % Conc. CH3COOH, % Temp. °C


II:62

1 1 20

0 0 0 0 0 0

0

1 1 BP

1 1 1 1 1 0 0 1 0 1 1 1 1

1 25 BP

2 0.5 BP

2 25 80

2 0.2 120

5 90 20

2 1 1 1 1 1 1 0 1 1 1 1

2 2 2 2 1 1 1 1 1 1 1 1 1 1

2 2 2 1 1 1 0

2 2 2 2 2 1 1 1

1 0 0 0 0

1

2

0

10 2 BP

2 2 2 2 2 2 2 2 1 2 2 2 2 2 2

10 90 20

1 0 0 0 0

1

S SULPHURIC ACID + ALUMINIUM SULPHATE

SULPHURIC ACID + ACETIC ACID + ACETIC ANHYDRIDE Conc. H2SO4, % Conc. CH3COOH, % Conc. (CH3CO)2O, % Temp. °C

0.4 71.3 28.3 135

5 47.5 47.5 20

5 47.5 47.5 40

5 47.5 47.5 80

Conc. H2SO4, % Conc. Al2(SO4)3, % Temp. °C

42 1.5 45


2 2 2 2 1

2 2 0 0 0 0 0

2 2 0 0 0 0 0

2 2 2 2 1


2 2 2 2 2 2 2 1

2

SULPHURIC ACID + AMMONIUM SULPHATE cont. Conc. H2SO4, % Conc. (NH4)2SO4, % Temp. °C

0.2 42 100

1 20 BP

1 40 80

1 40 BP

2 40 80

2 40 BP

5 10 40

5 20 40

5 20 60

5 20 80

5 20 BP

5 40 60


2 2 1 1 0 0 0 0

2 2 1 1 1 1 0 0

2 2 1 1 1 1 0 0 0

2 2 2 2 2 2 1 0 0 1 0 0 0 0 2

2 2 1 1 1 1 0 0

2 2 2 2 2 2 1 0

2 2 0 0 0 0 0 0

2 2 0 0 0 0 0 0

2 2 1 1 0 0 0 0

2 2 2 2 2 2 1 0

2 2 1 1 0 0 0 0

0

0

0

0

0 1

0 1

0 2

2 2 2 2 2 2 1 1 1 1 0 1 1 0 2

1

0 0 0 0 1

2

1

2

0 1

1

SULPHURIC ACID + AMMONIUM SULPHATE

Conc. H2SO4, % Conc. (NH4)2SO4, % Temp. °C BP

5 40 40

10 20 80

10 20 BP

10 20 40

10 40 80

10 40 100


2 2 1 1 0 0 0 0

2 2 2 2 1 1 1 0

2 2 2 2 2 2 1 1

2 2 1 1 0 0 0 0

2 2 2 2 1 1 1 1

2 2 2 2 2 2 1 1

2

2

2

2 2 2 2 2 2 1 1

10 51

2

2

2

2

2

II:63

S SULPHURIC ACID + CHLORIDES (200 ppm Cl – ) Conc. H2SO4, % Conc. Cl – , ppm Temp. °C


cont. 1 200 70

1 200 80

1 200 90

1 200 100

5 200 70

5 200 80

5 200 90

10 200 50

0

10 200 70

10 200 80

0

2

10 200 90

20 200 40

20 200 50

20 200 60

1 2

0

0 0 0

1 1

2

0 0

2 0

2 0

20 200 70

1

0 0

10 200 60

1

0

1

0

0 0 0

2

2 0 0

0

0 2 0 2

0

0

0 0 0

0

2 0 0

0 0

0

2

0

0

1 1

2 0

SULPHURIC ACID + CHLORIDES (200 ppm Cl – ) Conc. H2SO4, % Conc. Cl – , ppm Temp. °C


cont. 20 200 80

20 200 90

30 200 30

30 200 40

30 200 50

30 200 60

40 200 15

40 200 25

40 200 40

50 200 50

50 200 60

2 1

1 0 0

1 0 0

0 0

0

0

2 2

0

2

2

0 0 0

1 2

1

1 1 1

1

2 2

2

2



II:64

cont. 1 2000 70

1 2000 80

1 2000 90

1 3 2000 2000 100=BP 40

3 2000 50

0

0 0 0 0

5 2000 50

5 2000 60

5 2000 70

5 2000 80

5 2000 90

5 2000 100

1

1 0 0 0

0 0

0

1

1

0

0

0

0

10 2000 20

10 10 2000 2000 40 50

0

0 0 0 0

1 0 0 0

0 0 0

0

0

0

0

0

0

0

2

0 0 0 0 1 0 0

0 0 0 0 1 0

1 0 1 0 2 0

S SULPHURIC ACID + CHLORIDES (2000 ppm Cl – ) Conc. H2SO4, % Conc. Cl – , ppm Temp. °C


cont. 10 2000 60

10 2000 70

10 2000 80

15 2000 50

15 2000 60

20 2000 20

20 2000 30

0 0 0 0

1 0 0 0

0

0 2

0 2

0

0

0

1

2

1

2

20 2000 40

20 2000 50

30 2000 15

0

1 0 1 0

1 0

1

30 2000 30

30 2000 40

30 2000 50

40 2000 15

40 2000 30

1

0

0

2

1 0

1

2


50 2000 15


1

50 2000 30

60 2000 15

60 2000 30

0

1 1

1 1

1

1

70 2000 15

70 2000 30

80 2000 15

80 2000 30

90 2000 15

0

0

0

1

1

0 0

1 1

0 0

1 0

1

90 2000 30

98 2000 15

98 2000 30

0

0

1 2

SULPHURIC ACID + CHLORINE H2SO4 saturated with Cl2 Conc. % Temp. °C

40 25

50 25

60 40

82 50

96 50


2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

1p 1p 1p 1p

1p

0

0

2

2

II:65

S SULPHURIC ACID + CHROMIUM TRIOXIDE

Conc. H2SO4, % Conc. CrO3, % Temp. °C

1 3.5 35

1.5 1.5 BP

5 3.5 35

10 3.5 35

10 7 50

20 2 50


0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0

2 0 0 0 0 0 0 0

2 0 0 0 0 0 0 0

0 0 0 0 0

0 0 0 0 0

0

0

0

0

0

0

13 1.3 40

20 4 60

25 24 108

32 20 90

46 18 100

51 4 70

2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

0

0

0

0

14 1.5 40

16 12 120

16 13 90

65 0.05 38

65 1 38

0 0 0 0 0

0 0 0 0

0 0 0 0 0

0 0 0 0

0 0 0 0

0

0

1 1 1 1 0 0 0 0 0 0 1

0

0

0

1

80 0.5 80

80 5.5 25

96 0.3 80

2

0 0

0

SULPHURIC ACID + COPPER SULPHATE

Conc. H2SO4, % Conc. CuS04, % Temp. °C


4 1 20

8 0.05 80

8 1 20

8 5 20

10 10 BP

2 0 0 0 0 0 0

2 2 2 0 0 0 0

2 0 0 0 0 0 0

1 0 0 0 0 0 0

0

2

0

0

2 0 0 0 0 0 0 0 0 0 0 0 0 0

SULPHURIC ACID + HYDROFLOURIC ACID Conc. H2SO4, % 10 Conc. HF, % 2 Temp. °C 30


II:66

2

12 4 40

2

SULPHURIC ACID + IRON (II) SULPHATE

12 4 50

2

12 4 60

2

1 1

1 1 1 2 2 2

2

2

2

2

Conc. H2SO4, % Conc. FeS04, % Temp. °C

5 0.05 70

5 5 40

8 20 20

10 0.2 BP


2 2 2 2 0 0 0 0

2 2 0 0 0 0 0 0

2 2 0 0 0 0 0 0

2 2 2 2 2 2 2 1 1 2 2 2 2 2 0

2

0

0

12 14.6 100

17 7 60

0

2 2 1 1 0 0 0 0

0

0

S SULPHURIC ACID + IRON (III) SULPHATE

Conc. H2SO4, % Conc. Fe2(S04)3, % Temp. °C


2 0.02 BP

2 0 0 0 0

0

2 10 100

7 0.05 80

0 0 0 0 0

0 0 0 0 0

0

1


0.2 0.3 100 100 =BP =BP

1 1 1 1

1 1 1 1 1 0 1 0 0 0 0

2 60

0 0 0 0 0

2 2 0 0 0 0 0 0

10 2 BP

2 2 2 2 2 2 0 0 0 0 0 0 0 2

2

50 3 128

Conc. H2SO4, % Conc. MnO2, % Temp. °C

1


2

40 0.05 20

1 1 1 1 1 0

0

H2SO4 saturated with O2 Conc. % Temp. °C

0.2 100 =BP


2 2 1 1 0 0 0 0 2 1 0

1

8 0.05 80

SULPHURIC ACID + OXYGEN GAS,

20 40

2

7 10 80

0

SULPHURIC ACID + NITROGEN GAS, H2SO4 saturated with N2 Conc. % Temp. °C

SULPHURIC ACID + MANGANESE DIOXIDE

0.3 100 =BP

0.5 100 =BP

2 70

3 70

95 50

95 60

0

0

1

2

0

1

0

1

2

0 0 1 0 1 0 0

SULPHURIC ACID + POTASSIUM DICHROMATE

Conc. H2SO4, % Conc. K2Cr207, % Temp. °C

1 5 35

1.5 2.5 BP

10 5 35

51 6 70


0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0

2 0 0 0 0 0 0 0

2 2 2 2 2 2 2 2

0

0

0

0

SULPHURIC ACID + SODIUM cont. DICHROMATE 80 0.6 80

2

80 8 25

0 0

96 0.5 80

0

Conc. H2SO4, % 10 Conc. Na2Cr2O7, % 9 Temp. °C 50


20 2.6 50

20 5 60

0 0 0 0 0

0 0 0 0 0

1

0

0

II:67

S SULPHURIC ACID + SODIUM DICHROMATE

SULPHURIC ACID + SODIUM SULPHATE

Conc. H2SO4, % Conc. Na2Cr2O7, % Temp. °C

25 30 108

32 26 90

46 23 100

Conc. H2SO4, % Conc. Na2SO4, % Temp. °C

0.5 1 BP

0.5 4 BP

3 2 BP

5 15 95

13 20 50


2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2

2 2 2 2 2 2 2 2


2 2 1 1 1 1 1 0

2 2 1 1 1 1 1 0

2 2 2 2 2 2 2 1

2 2 2 2 2 2 2 1

2 2 2 2 1 1 1 0

0

0

0

13 20 60

25 24 30

1

2 2 2 2 0 0 0 0

0

2

0

2

1

1

1

SULPHURIC ACID + SULPHUR DIOXIDE H2SO4 saturated with SO2

cont.

Conc. % Temp. °C

0.5 90

0.5 100 =BP


2 2 2 2 1 0 0 0

2 2 2 2 2 2 2 1

0

0

2 70

0

5 70

1

10 50

20 40

20 60

30 20

30 80

50 20

60 20

2 2 2 2 1 1 1 0

2 2 2 2 1 1 1 0

2 2 2 2 2 2 2 2

2 2 2 2 1 1 1 0

2 2 2 2 2 2 2 2

2 2 2 2 2 1 1 0

2 2 2 2 2 2 2 0

0

0

1

0

2

0

2

SULPHURIC ACID + SULPHUR DIOXIDE


II:68

96 40

96 55

98 80

98 90

2

1

1 1 1 1 1

1 1 1 1 1

1

1 2

2

2

95 50

95 60

1

1

1

SULPHURIC ACID + ZINC SULPHATE

H2SO4 saturated with SO2 Conc. % Temp. °C

90 40

Conc. H2SO4, % 0.5 Conc. ZnSO4, % 30 Temp. °C BP

1 1 65

2 30-45 80

10 5 50


2 2 1 1 0 0 0 0 0 0 0 0 0 0 0

2 2 2 2 1 1 1 0

2 2 2 2 1 1 1 0 0 0 0 0 0 0 2

2 2 2 2 1 1 1 0 0 1 0 0 0 0 1

2

S, T SULPHUROUS ACID H2SO3 (SO2 dissolved in water) Conc. SO2, % Temp. °C

2 50

5 20

10 160

20 20

satd 20

satd 135

satd 200


2 2 0 0 0 0 0 0

0 0 0 0

2 2 1 1 0 0 0 0

2 2 1 1 0 0 0 0

2 2 1 1 0 0 0 0

2 2 1 1 0 0 0 0

2 2 2 2 1 0 0 0

0

0

0

0

0

0

0

SULPHUROUS ACID + CALCIUM BISULPHITE

Conc. H2SO3, % Conc. Ca(HSO3) 2, % Temp. °C

1-2 1-5 140


2 2 0 1 0 0 0 0

SYRUP AND SUGAR

Conc. %

The given values are for the liquid phase and the air-free gaseous phase. If air is present, attacks by sulphuric acid can occur in the gaseous phase. The values are also applicable when calcium bisulphite is replaced by magnesium bisulphite, sodium bisulphite or ammonium bisulphite.

0

TALL OIL

All

Temp. °C

With an addition of Cl – , 500 mg/l 20-BP 90


0 0 0 0 0 0 0 0 0 0 0 0 0 0

0p 0p 0p 0p 0p 0p 0p

0

TANNIC ACID Tannin

Temp. °C

100

Carbon steel 13% Cr-steel 18-2 18-10 0 17-12-2.5 0 18-13-3 0 17-14-4 0 904L 0 Sanicro 28 0 254 SMO 0 654 SMO 0 SAF 2304 0 2205 0 SAF 2507 0 Ti 0

300

2 1 0 0 0 0

0

904L and 254SMO are used for crude tall oil containing traces of sulphuric acid.

Conc. % Temp. °C

5 20

5 BP

10 20

10 BP

25 100

50 65

50 BP


1 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

1 0 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0

II:69

T TAR

TARTARIC ACID

pure

C2H2 (OH)2 (COOH)2

Temp. °C


cont.

20BP

Conc. % Temp. °C

1 90

1 100 =BP

20 70

20 100

30 60

30 90

30 102 =BP

50 50

50 70

50 90

0 0 0 0 0 0 0 0 0 0 0 0 0 0


2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 1

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 1

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 1 0 0 0 0 0 0 0 0 0 0 1

2 2 0 1 0 0 0 0 0 0 0 0 0 0 1

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 1

2 2 0 1 0 0 0 0 0 0 0 0 0 0 1

TARTARIC ACID

TARTARIC ACID + SULPHURIC ACID

C2H2 (OH)2 (COOH)2 Conc. % Temp. °C

50 106 =BP

60 80

60 100

70 114 =BP

75 100

75 118 =BP

Conc. tartaric, % Conc. H2SO4, % Temp. °C


2 2 0 2 1 1 1 1 0 0 0 0 0 0 2

2 2 0 1 0 0 0 0 0 0 0 0 0 0 1

2 2 0 2 1 1 1 1 0 0 0 0 0 0 1

2 2 0 2 1 1 1 1 0 0 0 0 0 0 1

2 2 0 2 1 1 1 1

2 2 2 2 1 1 1 1


1

TARTARIC ACID Temperature, C 140 °

120 18-2 100

17-12-2.5

80 18-10

60 40 20

0

20

40

60 80 100 C2H2(OH)(COOH)2, weight-%

Isocorrosion diagram, 0.1 mm/year, in tartaric acid. Broken- line curve represents the boiling point and chain line curve represents solubility.

II:70

1

satd 4 40

satd 4 60

satd 4 80

0 0

1 0

2 1

0

0

1

0

1

1

T TEXTILE DYES

THIONYL CHLORIDE

basic, neutral and acidic.

SOCl2

Temp. °C


BP

0 0 0 0 0 0 0 0 0 0 0 0 0

Conc. % Temp. °C

100 2040


2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

Risk of pitting and stress corrosion of stainless steels in presence of moisture.

TIN

TINCTURE OF IODINE

Sn

10% solution of I2 in ethanol

Conc. % Temp. °C


Temp. °C

Molten 300

350

400

500

700

2

2

2

2

2

1 1 1 1

2 2 2 2

2 2 2 2

1

1

0 0 0 0 0

0

0

TOLUENE

TRICHLOROETHYLENE

C6H5CH3

C2HCl3. Technical grade

Conc. % Temp. °C


100 BP

Conc. % Temp. °C

0 0 0 0 0 0 0 0 0 0 0 0 0 0



100 20

100 BP

0 0 0 0 0 0 0 0 0 0 0 0

2 2 0 0 0 0 0 0 0 0 0 0 0 0 0

20

0p 0p 0p 0p 0p 0p

0

Risk of pitting and stress corrosion of stainless steels in presence of moisture.

II:71

T–Y TURPENTINE

UREA

turpentine oil

CO(NH2)2

URINE

Temp. °C

20

Temp. °C


0 0 0 0 0 0 0 0 0 0 0 0 0 0


VINEGAR

180

0 0 0 0

0

Temp. °C


0-60

0p 0p 0p 0p 0p

No risk of pitting if continuous or periodic water rinse is provided.

0

WHITE LIQUOR,

WATER

with 1 % NaCl Conc. % Temp. °C


WINES

4-5 20

see the first section of the handbook 0 0 0 0 0 0 0 0 0 0 0 0 0

XYLENE C6H4(CH3)

see FRUIT JUICES

II:72

Temp. °C

180


0 0 0 0 0 0 0 0 0 0 0 0

YEAST 2

Conc. % Temp. °C

All conc. BP


0 0 0 0 0 0 0 0 0 0 0 0 0 0

Temp. °C


20BP

0 0 0 0 0 0 0 0 0 0 0 0 0 0

Z ZINC

ZINC CARBONATE

ZINC CHLORIDE

Zn

ZnCO3

ZnCl2

Conc. % Temp. °C

Molten 500

Conc. % Temp. °C

All conc. 20


2 2 2 2 2 2 2 2


0 0 0 0 0 0 0 0 0 0 0 0 0 0

2

cont.

Conc. % Temp. °C


ZINC CHLORIDE

ZINC CYANIDE

ZINC NITRATE

ZnCl 2

Zn(CN)2

Zn(NO3)2

Conc. % Temp. °C


2070 150

75

80

200

150

2 2 P 1ps 0ps 0ps 0ps 0ps

2 2 P 2 1ps 0ps 0ps 0ps

2 2 P 2 1ps 1ps 0ps 0ps

0

1p

1p

Conc. % Temp. °C



0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0

11 80

11 100

20 80

20 100

2 P 2 1ps 1ps 1ps 0ps

2 P 2 2 2 2 1ps

2 P 2 1ps 1ps 1ps 0ps

2 P 2 2 2 2 1ps

0

0

0

0

BP

2 2 0 0 0 0 0 0 0 0 0 0 0 0

0


ZrOCl2 Conc. % Temp. °C

0

75 175

ZnSO4 40

0p 0p 0p 0p 0p 0p 0p

2 1p P 1ps 0ps 0ps 0ps 0ps

Conc. % Temp. °C

ZIRCONIUM OXYCHLORIDE

20 20BP

520 BP

All conc. 20

ZINC SULPHATE

Conc. % Temp. °C

520 20

1 0 0 0 0 0 0 0 0 0 0 0


II:73

Physical tables Density, modulus of elasticity and coefficient of linear expansion of stainless steels Coefficient of linear expansion (x 106) per °C

Steel grade

SS

Carbon steel

Density

Modulus of elasticity 20°C – (x10 – 3) 100°C

–200°C –400°C –600°C

–800°C

–1000 °C

7.8

210

12

13

14

–

–

–

13Cr

2301

7.7

225

11

11

12

12

13

–

18-2

2326

7.7

220

10

11

11.5

12

13

13

18-10

2332, 2333 2337, 2338 2352, 2371

7.9

200

17

17

18

19

19

20

17-12-2.5

2347, 2348 2350, 2343 2353, 2375

8.0

200

16.5

17

18

19

20

20

18-13-3

2366, 2367

8.0

200

16

17

18

19

19

19.5

17-14-4

–

8.0

200

16

17

18

19

19

–

904L

2562

8.1

195

15

16

17

17

18

19

Sanicro 28

2584

8.0

200

15

16

17

–

–

–

254 SMO

2378

8.0

190

16

16

17

17

18

18

654 SMO

–

8.0

180

15

15

16

17

18

18

SAF 2304

2327

7.8

200

13

14

15

15

16

17

2205

2377

7.9

200

13.0

14

15

16

17

18

SAF 2507

2328

7.8

200

13.0

14

15

15

16

17

4.5

110

9

9

10

10

–

–

Titanium

Thermal conductivity of stainless steels

Steel grade

SS

Carbon steel

Thermal conductivity, W / m • °C 20°C 100°C 200°C

400°C

600°C

800°C

52

51

49

43

–

–

13Cr

2301

23

24

24

26

–

–

18-2

2326

23

24

24

26

–

–

18-10

2332, 2333 2337, 2338 2352, 2371

15

16

18

20

22

25

17-12-2.5

2347, 2348 2350, 2343 2353, 2375

13

14

15

18

21

24

18-13-3

2366, 2367

13

14

15

18

21

24

17-14-4

–

15

15

16

20

21

24

904L

2562

15

15

16

20

21

–

Sanicro 28

2584

11

13

14

17

–

–

254 SMO

2378

13

14

15

18

–

–

654 SMO

–

9

10

11

15

–

–

SAF 2304

2327

16

17

18

21

25

–

2205

2377

14

15

17

20

24

SAF 2507

2328

14

15

16

20

24

–

19

19

20

20

–

–

Titanium II:74

Physical properties of certain chemical elements Chemical element

Symbol

Density at 20°C

Coefficient of linear expansion at 0–100°C (x 106)

Thermal conductivity at 20°C W / m • °C

Aluminium Antimony Arsenic

Al Sb As

2.70 6.68 5.78

23.7 9.4 4.7

219 19 –

Beryllium Bismuth Boron

Be Bi B

1.85 9.78 3.33

11.6 13.4 8

147 8 –

Calcium Carbon (diamond) Carbon (graphite) Chromium Cobalt Copper

Ca C C Cr Co Cu

1.54 3.51 2.26 7.23 8.89 8.94

19 1.3 2.0 6.8 12.6 16.2

126 1.56 0.49 68 69 394

Gold

Au

19.31

14.4

Iron

Fe

7.87

Lead Lithium

Pb Li

Magnesium Manganese

Melting point °C

660 631 817 (28 atm) 1283 271 2300

Boiling point °C

2467 1380 613 (subl.) 2970 1560 2250 (subl.)

845 >3550 >3550 1890 1492 1083

1487 4827 4827 2482 2900 2595

307

1063

2966

12.3

79

1535

3000

11.34 0.53

28.9 60

35 71

327 179

1744 1371

Mg Mn

1.74 7.50

149 –

651 1244

1107 2097

Mercury Molybdenum

Hg Mo

13.55 10.2

26.1 23 1821) 5.2

8 144

–39 2610

357 5560

Nickel Niobium

Ni Nb

8.90 8.56

13.1 8

92 55

1453 2468

2732 4927

Palladium Phosphorus (yell.) Platinum Potassium

Pd P Pt K

11.9 1.83 21.4 0.86

11.7 125 9.0 84

70 – 71 100

1552 44 1769 64

2927 280 3830 774

Selenium Silicon Silver Sodium Sulphur

Se Si Ag Na S

4.8 2.33 10.49 0.96 2.07

38 2.5 19.0 70 64

– 84 418 134 –

217 1410 961 98 119

685 2355 2212 892 445

Tantalum Tin Titanium Tungsten

Ta Sn Ti W

16.7 7.31 4.50 19.3

6.5 23 8.9 4.3

55 62 19 168

2996 232 1675 3380

5400 2270 3260 5927

Vanadium

V

6.11

8.3

31

1900

3380

Zinc Zirconium

Zn Zr

7.13 6.50

111 21

419 1852

907 3578

30 6

Coefficient of cubical expansion

1)

II:75

Temperature conversion table Start with the temperature value appearing in the centre column. If initial value is in Celsius degrees the corresponding value in Fahrenheit degrees will appear in the right-hand column. If initial value is in Fahrenheit degrees the corresponding value in Celsius degrees will appear in the left-hand column. (°C = 5 / 9 (°F -32) and °F = 9 / 5°C + 32). °C

°C / °F

–40 –34 –29 –23 –17.8

–40 –30 –20 –10 0

–17.2 –16.7 –16.1 –15.6 –15.0

1 2 3 4 5

–14.4 –13.9 –13.3 –12.8 –12.2

°F

°C / °F

°F

6.1 6.7 7.2 7.8 8.3

43 44 45 46 47

109.4 111.2 113.0 114.8 116.6

32.2 32.8 33.3 33.9 34.4

90 91 92 93 94

194.0 195.8 197.6 199.4 201.2

33.8 35.6 37.4 39.2 41.0

8.9 9.4 10.0 10.6 11.1

48 49 50 51 52

118.4 120.2 122.0 123.8 125.6

35.0 35.6 36.1 36.7 37.2

95 96 97 98 99

203.0 204.8 206.6 208.4 210.2

6 7 8 9 10

42.8 44.6 46.4 48.2 50.0

11.7 12.2 12.8 13.3 13.9

53 54 55 56 57

127.4 129.2 131.0 132.8 134.6

37.8 43 49 54 60

100 110 120 130 140

212.0 230 248 266 284

–11.7 –11.1 –10.6 –10.0 – 9.4

11 12 13 14 15

51.8 53.6 55.4 57.2 59.0

14.4 15.0 15.6 16.1 16.7

58 59 60 61 62

136.4 138.2 140.0 141.8 143.6

66 71 77 82 88

150 160 170 180 190

302 320 338 356 374

– – – – –

8.9 8.3 7.8 7.2 6.7

16 17 18 19 20

60.8 62.6 64.4 66.2 68.0

17.2 17.8 18.3 18.9 19.4

63 64 65 66 67

145.4 147.2 149.0 150.8 152.6

93 99 100 104 110

200 210 212 220 230

392 410 413.6 428 446

– – – – –

6.1 5.6 5.0 4.4 3.9

21 22 23 24 25

69.8 71.6 73.4 75.2 77.0

20.0 20.6 21.1 21.7 22.2

68 69 70 71 72

154.4 156.2 158.0 159.8 161.6

116 121 127 132 138

240 250 260 270 280

464 482 500 518 536

– – – – –

3.3 2.8 2.2 1.7 1.1

26 27 28 29 30

78.8 80.6 82.4 84.2 86.0

22.8 23.3 23.9 24.4 25.0

73 74 75 76 77

163.4 165.2 167.0 168.8 170.6

143 149 154 160 166

290 300 310 320 330

554 572 590 608 626

– 0.6 0 0.6 1.1 1.7

31 32 33 34 35

87.8 89.6 91.4 93.2 95.0

25.6 26.1 26.7 27.2 27.8

78 79 80 81 82

172.4 174.2 176.0 177.8 179.6

171 177 182 188 193

340 350 360 370 380

644 662 680 698 716

2.2 2.8 3.3 3.9 4.4

36 37 38 39 40

96.8 98.6 100.4 102.2 104.0

28.3 28.9 29.4 30.0 30.6

83 84 85 86 87

181.4 183.2 185.0 186.8 188.6

199 204 210 216 221

390 400 410 420 430

734 752 770 788 806

5.0 5.6

41 42

105.8 107.6

31.1 31.7

88 89

190.4 192.2

227 232

440 450

824 842

II:76

–40 –22 –4 14 32

°C

°C

°C / °F

°F

°C

°C / °F

238 243 249 254 260

460 470 480 490 500

266 271 277 282 288

°F

°C

°C / °F

°F

860 878 896 914 932

393 399 404 410 416

740 750 760 770 780

1364 1382 1400 1418 1436

510 520 530 540 550

950 968 986 1004 1022

421 427 432 438 443

790 800 810 820 830

293 299 304 310 316

560 570 580 590 600

1040 1058 1076 1094 1112

449 454 460 466 471

321 327 332 338 343

610 620 630 640 650

1130 1148 1166 1184 1202

349 354 360 366 371

660 670 680 690 700

377 382 388

710 720 730

°C

°C / °F

°F

560 571 582 593 604

1040 1060 1080 1100 1120

1904 1940 1976 2012 2048

1454 1472 1490 1508 1526

616 627 638 649 660

1140 1160 1180 1200 1220

2084 2120 2156 2192 2228

840 850 860 870 880

1544 1562 1580 1598 1616

671 682 693 704 732

1240 1260 1280 1300 1350

2264 2300 2336 2372 2462

477 482 488 493 499

890 900 910 920 930

1634 1652 1670 1688 1706

760 788 816 843 871

1400 1450 1500 1550 1600

2552 2642 2732 2822 2912

1220 1238 1256 1274 1292

504 510 516 521 527

940 950 960 970 980

1724 1742 1760 1778 1796

899 927 954 982 1010

1650 1700 1750 1800 1850

3002 3092 3182 3272 3362

1310 1328 1346

532 538 549

990 1000 1020

1814 1832 1868

1038 1066 1093

1900 1950 2000

3452 3542 3632

II:77

Chemical elements Atomic weight

Chemical element

Symbol

89 13 95 51 18 33 85

227 26.98 243 121.75 39.95 74.92 210

Mercury Molybdenum

Hg Mo

80 42

200.59 95.94

Ba Bk Be Bi B Br

56 97 4 83 5 35

137.34 247 9.01 208.98 10.81 79.90

Neodymium Neon Neptunium Nickel Niobium Nitrogen Nobelium

Nd Ne Np Ni Nb N No

60 10 93 28 41 7 102

144.24 20.18 237 58.71 92.91 14.01 254

Osmium Oxygen

Os O

76 8

190.2 16.00

Cadmium Calcium Californium Carbon Cerium Cesium Chlorine Chromium Cobalt Copper Curium

Cd Ca Cf C Ce Cs Cl Cr Co Cu Cm

48 20 98 6 58 55 17 24 27 29 96

112.40 40.08 251 12.01 140.12 132.91 35.45 52.00 58.93 63.55 247

Palladium Phosphorus Platinum Plutonium Polonium Potassium Praseodymium Promethium Protactinium

Pd P Pt Pu Po K Pr Pm Pa

46 15 78 94 84 19 59 61 91

106.4 30.97 195.09 244 209 39.10 140.91 145 231

Dysprosium

Dy

66

162.50

Einsteinium Erbium Europium

Es Er Eu

99 68 63

254 167.26 151.96

Radium Radon Rhenium Rhodium Rubidium Ruthenium

Ra Rn Re Rh Rb Ru

88 86 75 45 37 44

226 222 186.2 102.91 85.47 101.07

Fermium Fluorine Francium

Fm F Fr

100 9 87

257 19.00 223

Gadolinium Gallium Germanium Gold

Gd Ga Ge Au

64 31 32 79

157.25 69.72 72.59 196.97

Samarium Scandium Selenium Silicon Silver Sodium Strontium Sulphur

Sm Sc Se Si Ag Na Sr S

62 21 34 14 47 11 38 16

150.35 44.96 78.96 28.09 107.87 22.99 87.62 32.06

Hafnium Helium Holmium Hydrogen

Hf He Ho H

72 2 67 1

178.49 4.00 164.93 1.01

Indium Iodine Iridium Iron

In I Ir Fe

49 53 77 26

114.82 126.90 192.2 55.85

Tantalum Technetium Tellurium Terbium Thallium Thorium Thulium Tin Titanium Tungsten

Ta Tc Te Tb Tl Th Tm Sn Ti W

73 43 52 65 81 90 69 50 22 74

180.95 97 127.60 158.92 204.37 232.04 168.93 118.69 47.90 183.85

Krypton

Kr

36

83.80

Uranium

U

92

238.03

Lanthanum Lawrencium Lead Lithium Lutecium

La Lr Pb Li Lu

57 103 82 3 71

138.91 257 207.19 6.94 174.97

Vanadium

V

23

50.94

Xenon Ytterbium Yttrium

Xe Yb Y

54 70 39

131.30 173.04 88.91

Magnesium Manganese Mendelevium

Mg Mn Md

12 25 101

24.31 54.94 256

Zinc Zirconium

Zn Zr

30 40

65.37 91.22

Chemical element

Symbol

Actinium Aluminium Americium Antimony Argon Arsenic Astatine

Ac Al Am Sb Ar As At

Barium Berkelium Beryllium Bismuth Boron Bromine

II:78

Atomic number

Atomic number

Atomic weight

Degrees Baumé – Density °Be = 145 –

145 density

At a density of <1: °Be =

140 density

– 130

°Be

Density

°Be

Density

°Be

Density

°Be

Density

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

1.000 1.007 1.014 1.021 1.028 1.036 1.043 1.051 1.058 1.066 1.074 1.082 1.090 1.099 1.107 1.115 1.124 1.133

18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

1.142 1.151 1.160 1.169 1.179 1.189 1.198 1.208 1.219 1.229 1.239 1.250 1.261 1.272 1.283 1.295 1.306 1.318

36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53

1.330 1.343 1.355 1.368 1.381 1.394 1.408 1.422 1.436 1.450 1.465 1.480 1.495 1.510 1.526 1.543 1.560 1.576

54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70

1.593 1.611 1.629 1.648 1.667 1.686 1.706 1.726 1.747 1.768 1.790 1.813 1.835 1.859 1.883 1.908 1.933

Vapour pressure of water 1 kgf /cm2 = 1 at 1 at = 0.9678 atm

1 kgf /cm2 = 98.0665 kPa 1 Pa = 10.1972 x 10 –6 kgf / cm2 1 Pa = 10 x 10 –6 bar

1 kgf /cm2 = 0.980665 bar 1 bar = 1.01972 kgf / cm2 1 bar = 100 kPa

°C

mm Hg

millibar

kPa

kgf /cm2

°C

mm Hg

millibar

kPa

kgf /cm2

100 101 102 104 106 108 110 112 114 116

760 788 816 875 938 1004 1075 1149 1227 1310

1010 1049 1089 1167 1245 1334 1432 1530 1638 1746

101 104 109 117 125 133 143 153 164 175

1.03 1.07 1.11 1.19 1.27 1.36 1.46 1.56 1.67 1.78

118 120 130 140 150 160 180 200 250 300

1397 1489 2026 2710 3750 4636 7520 11659 29818 64433

1863 1981 2697 3609 4756 6178 10022 15544 39746 85906

186 198 270 361 476 618 1002 1554 3975 8591

1.90 2.02 2.75 3.68 4.85 6.30 10.22 15.85 40.53 87.60


6839

250

200

150

100

1

2

5

10

20

50

100 bar

Vapour pressure of water

II:79

pH-values for alkaline solutions, 20°C

pH-values for foods Apples Bananas Beer Blackberries Carrots Cherries Cider Drinking water Gooseberries Grapefruit Lemons Milk Olives Oranges Pears Pickles Sauerkraut Soft drinks Strawberries Tomatoes Vinegar Wines

Concentration

Ammonium hydroxide, NH4OH Ammonium hydroxide, NH4OH Ammonium hydroxide, NH4OH Borax , Na2B4O7 • 10H2O Calcium carbonate, CaCO3 Calcium hydroxide, Ca(OH)2 Iron hydroxide, Fe(OH)2 Magnesium hydroxide, Mg(OH)2 Potassium cyanide, KCN Potassium hydroxide, KOH Potassium hydroxide, KOH Potassium hydroxide, KOH Sodium bicarbonate, NaHCO3 Sodium carbonate, Na2CO3 Sodium hydroxide, NaOH Sodium hydroxide, NaOH Sodium hydroxide, NaOH Sodium phosphate, Na3PO4 Sodium silicate, Na2SiO3

M

wt. %

pH

1.0 0.1 0.01 0.025 – – – – 0.1 1.0 0.1 0.01 0.1 0.5 1.0 0.1 0.01 0.033 0.5

1.7 0.17 0.02 1.0 saturated saturated saturated saturated 0.65 5.4 0.58 0.06 0.84 0.53 3.9 0.40 0.04 0.55 0.61

11.6 11.1 10.6 9.2 9.4 12.4 9.5 10.5 11.0 14.0 13.0 12.0 8.4 11.6 14.0 13.0 12.0 12.0 12.6

2.9–3.3 4.5–4.7 4.0–5.0 3.2–3.6 4.9–5.3 3.2–4.0 2.9–3.3 6.5–8.0 2.8–3.0 3.0–3.3 2.2–2.4 6.3–6.6 3.6–3.8 3.0–4.0 3.6–4.0 3.0–3.4 3.4–3.6 2.0–4.0 3.0–3.5 4.0–4.4 2.4–3.4 2.8–3.8

pH-values for substances in the human body Blood plasma Gastric acid Mother’s milk Saliva Urine

7.3–7.5 1.0–3.0 6.6–7.6 6.5–7.5 4.8–8.4

pH-values for acid solutions, 20°C Concentration

Acid dissociation constants

M

wt. %

pH

pKa1

pKa2

pKa3

Acetic acid, CH3COOH

1.0

6.0

2.4

4.75

–

–


0.1

0.60

2.9

4.75

–

–


0.01

0.06

3.4

4.75

–

–

Benzoic acid, C6H5COOH

0.01

0.12

3.1

4.19

–

–

Boric acid, HB(OH)3

0.03

0.21

5.2

9.14

12.74

13.8

Carbonic acid, H2CO3

–

saturated

3.8

6.37

10.33

–

Citric acid, C3H4OH (COOH)3

0.03

0.64

2.2

3.14

4.77

6.39

Formic acid, HCOOH

0.1

0.46

2.3

3.75

–

–

Hydrocyanic acid, HCN

0.1

0.23

5.1

9.22

–

–

Hydrogen sulphide, H2S

0.05

0.17

4.1

7.04

11.96

–

Lactic acid, C2H4OHCOOH

0.1

0.90

2.4

3.08

–

–

Malic acid, C2H3(OH)(COOH)2

0.05

6.0

2.4

3.40

5.11

–

Oxalic acid, (COOH)2

0.05

0.43

1.6

1.23

4.19

–

Phosphoric acid, H3PO4

0.03

0.33

1.5

2.12

7.21

12.67

Sulphurous acid, H2SO3

0.05

0.41

1.5

1.81

6.91

–

Tartaric acid, C2H2(OH)2(COOH)2

0.05

0.75

2.2

2.98

4.34

–

II:80

pH-values for hydrochloric acid, nitric acid and sulphuric acid solutions, 20°C

Conc. Density

Hydrochloric acid 38% 1.1885

Nitric acid 65% 1.39125

pH

g/l

ml / l

g/l

ml / l

g/l

ml / l

1.0 1.3 1.6 1.9 2.2 2.5 2.8 3.1 3.4 3.7 4.0 4.3 4.6 4.9 5.2

9.6 4.8 2.4 1.2 0.61 0.30 0.15 0.076 0.038 0.019 0.0096 0.0048 0.0024 0.0012 0.00060

8.1 4.1 2.0 1.0 0.51 0.25 0.13 0.064 0.032 0.016 0.0081 0.0040 0.0020 0.0010 0.0005

9.7 4.9 2.4 1.2 0.61 0.31 0.15 0.077 0.039 0.019 0.0097 0.0049 0.0024 0.0012 0.00061

7.0 3.5 1.8 0.88 0.44 0.22 0.11 0.055 0.028 0.014 0.0070 0.0035 0.0018 0.00088 0.00044

10.2 5.1 2.6 1.3 0.64 0.32 0.16 0.081 0.041 0.020 0.010 0.0051 0.0026 0.0013 0.00064

5.6 2.8 1.4 0.70 0.35 0.18 0.088 0.044 0.022 0.011 0.0055 0.0028 0.0014 0.00070 0.00035

1.1

Sulphuric acid 96% 1.8355

Acetic acid

6840

Diagram showing the relationship between weight-% and density, molarity, volume-% and kg/litre. Normal commercial concentration: 99.5 wt.% (glacial acetic acid).

1.0 0.9 0.8 e r t t 0.7 l r e p 0.6 H O O C0.5 3 H C g 0.4 k

90

0.2

80

0.1

1.06

0

y1.04 t i s n e D1.03

1.02

100

0.3

1.07

1.05

kg/l

) H 70 O O C 60 3 H C 50 % t w 5 . 40 9 9 (

Density

Vol.-%

% 30 . l o V

20

1.01

10

1.00

0

20 y t i r a 10 l o M

Molarity

0

20

40

60

80 100 CH3COOH, weight-%

0

II:81

Ammonium hydr oxide Diagram showing the relationship between weight-% and density, molarity, volume-% and kg/litre and degrees Baumé. Normal commercial concentration: 25 wt.-% (density = 0.91).

6841

é

30 m u a B 20 s e e r g 10 e D

Bé

°

0.4 e r 0.3 t t l r e p 30.2 H N g k 0.1

0

kg/l

100 90 Vol.-%

80 ) 370 H N % - 60 t w 5 2 ( 50 % . l o 40 V

20 Molarity

30 0.80

20

y t i s0.90 n e D

10

1.00

Formic acid Diagram showing the relationship between weight-% and density, molarity, volume-% and kg/litre and degrees Baumé. Normal commercial concentration: 98–100 wt.-%.

Density

0

10

20

30

1.3

40 50 NH3 , weight-%

6842

1.2

0

30 é

m u

a 20 B

Bé

°

s e r 10 e g e D

1.1 1.0

0

0.9

30

e r 0.8 t t l r e p 0.7 H O O C0.6 H g k

80 H 70 O O C H 60

40

1.3

30

1.2

20

1.0

Vol.-%

% . l o 50 V

0

y t i s n e1.1 D

0 kg/l

0.4

0.1

a l o M 10

100 90

0.2

y i 20 t r

Molarity

0.5

0.3

II:82

0

y t i r a 10 l o M

Density

10 0

0

20

40

60


6843

0.5

Bé

°

0.4 e r t t 0.3 l r e p l 0.2 C H g k 0.1

30 é

m u a 20 B s e r 10 e g e D

0

kg/l

Hydrochloric acid Diagram showing the relationship between weight-% and density, molarity, volume-%, kg/litre and degrees Baumé. Normal commercial concentration: 98 wt.-%.

20

y t i r a 10 l o M

Molarity

0

0 100 90 80 ) l C 70 H % . 60 t w 8 3 ( 50

Vol.-%

% . l o 40 V

30 1.19

y t i s n e1.10 D

1.00

20 Density 10 0

0

1.6

10

20

30

40 50 HCl, weight-%

Nitric acid

50

6844

1.4

40 Bé

°

1.2

30 é

1.0

a 20 B

m u

s e r 10 e g e D

0.8 e r 0.6 t t l r e p 0.4 3 O N H0.2 g k

0

kg/l

Diagram showing the relationship between weight-% and density, molarity, volume-%, kg/litre and degrees Baumé. Normal commercial concentration: 65 wt.-% (density = 1.40).

0

100 90 80

1.60 1.50 1.40 y t i 1.30 s n e D

1.20

Vol.-%

) 370 O N H 60 % . t w 5 50 6 ( % 40 . l o V

Density

30

30

20

20

y t i r l 10 a o M

Molarity 1.10

10

1.00

0 0

20

40

60

80 100 HNO3, weight-%

0

II:83

Phosphoric acid Diagram showing the relationship between weight-% and density, molarity, volume-%, kg/litre and degrees Baumé. Normal commercial concentration: 85 wt.-% (density = 1.70).

1.6 1.4 1.2 1.0

e r t t l r 0.8 e p 4 O0.6 P 3 H g k 0.4

0.2

60 50 100 90

1.80

80

1.60 1.50 1.40 y t i 1.30 s n e D

Diagram showing the relationship between weight-% and density, molarity, kg/litre and degrees Baumé. Normal commercial concentration: 50 wt.-%.

70 kg/l

0

1.70

Potassium hydroxide

6845

é m u 40 a B s e 30 e r g e D

Bé

°

20

) 470 O P 3 H 60 % . t w 50 5 8 (

10 0 Vol.-%

40 % . l o V 30 Density

1.20

20

1.10

10

1.00

0

10

y t i r a 5 l o M

Molarity

0

1.0

20

40

60


0

60

6846

Bé

°

0.9

50

é m u 40 a B s e 30 e r g e D

0.8 kg/l 0.7 0.6

20

0.5

10

e r t t l r 0.4 e p H O0.3 K g k

0

0.2 0.1 0 Density 1.60 1.50 1.40

y t i 1.30 s n e D

Molarity

1.20

20

y t i r l 10 a o M

1.10 1.00

II:84

0

20

40

60

80

100 KOH, weight-%

0

S odium hydroxide

50

6847

é

40 m u a B 30 s e e r g 20 e D

Bé

°

0.8 0.7 0.6

10

0.5

0

e r t t l r 0.4 e p H O0.3 a N g k 0.2

Diagram showing the relationship between weight-% and density, molarity, kg/litre and degrees Baumé. Normal commercial concentration: 50 wt.-%.

kg/l

0.1 0 1.60 1.50 1.40 Density

y t i s1.30 n e D

20

1.20

y t i r a 10 l o M

Molarity

1.10 1.00

0

10

20

30

40

50

0

NaOH, weight-%

2.0

1.90

1.8

60

1.6

50 é

1.70

0.6

100

1.60

0.4

90

0.2

80

1.30 1.20 1.10 1.0

0

Diagram showing the relationship between weight-% and density, molarity, volume-%, kg/litre and degrees Baumé. Normal commercial concentration: 96 wt.-% (density 1.84).

20

0.8

1.40

m u a B 40 s e e r 30 g e D

Bé

°

e r 1.4 t t l r e p 1.2 4 O S 21.0 H g k

1.80

y t i s n1.50 e D

S ulphuri c acid

70

6848

10

kg/l

0

Density

) 470 O S 2 H 60 % t w 50 5 9 ( 40 % . l o V

Vol.-% 20

30

15

20

y

t r 10 i

Molarity

10 0

5

0

20

40

60


a l o M

0

II:85

G lossary The definitions in the following glossary of common corrosion terms have been taken mainly from the Corrosion Dictionary (TNC 67) published by the Swedish Centre of Technical Terminology, Stockholm 1977. Accelerated corrosion testing Testing, in which the rate of corrosion is increased by making conditions more severe than what is found in practice.

Cathodic protection Electrochemical corrosion protection by lowering the electrode potential. Chlorides Corrosive ions which are the most common reason for localised corrosion such as pitting, crevice corrosion and stress corrosion cracking.

Activation Changing the condition of steel from passive to active.

Chlorine Presence of moisture or aqueous solutions of chlorine may lead to high corrosion rates and pitting.

Activation potential The electrode potential, at which a steel is changed from passive to active condition.

Corrosion Attack on a material through chemical or electrochemical reaction with a surrounding medium.

Active condition Condition in which a steel can be dissolved or corroded.

Corrosion fatigue Fatigue due to the effect of a corrosive medium.

Active-passive cell A local cell consisting of a section in the active condition, acting as an anode, and a section in the passive condition, acting as a cathode. Commonly, oxygen reduction takes place at the cathode surface and metal dissolution at the anode surface.

Corrosion product Reaction product formed through corrosion.

Anode An electrode, from which a positive electric current enters an electrolyte. The electrode reaction at an anode is oxidation, for instance a) Oxidation of metal atoms in the anode material under production of ions in the electrolyte, e.g. Fe  Fe2+ + 2e– b) Oxidation of ions or molecules in the electrolyte under production of electrons (collected by the anode), e.g., Fe2+  Fe3+ + e– Anodic protection Electrochemical corrosion protection, achieved by increasing the electrode potential of the steel. Atmospheric corrosion Corrosion due to exposure at atmosphere, generally out of doors. Atmospheric corrosion testing Field trials in atmosphere. Bright annealing Annealing in inert gas or vacuum to prevent oxidation of the surface. Cathode An electrode, through which positive electric current leaves an electrolyte. The electrode reaction at a cathode is a reduction of ions or molecules in the electrolyte by electrons emitted from the cathode. In corrosion processes, reduction of dissolved oxygen and emission of hydrogen are two common reactions. The current flow causes positive ions to migrate towards the cathode.

II:86

Corrosive solution A solution that can cause corrosion. Crevice corrosion Localised corrosion in narrow crevices filled with liquid. Electrochemical corrosion Corrosion brought about through electrode reactions. Electrochemical protection The prevention of corrosion in an electrolyte by control of the electrode potential of steel. Electrode Electron conductor, through which electrons can enter and leave an electrolyte. Cf. Anode and Cathode. Electrode potential Potential difference between a test electrode and a reference electrode, e.g., a saturated calomel electrode, in a solution. Electrode reaction A chemical reaction at the surface of an electrode, in connection with electric current flow. The reaction is a reduction in one direction, oxidation in the other. Electrolyte An electrically conducting medium, such as melted salt or a salt solution, in which electric current is transported by ions. Erosion corrosion Attack consisting of simultaneous erosion and corrosion through the effect of a rapidly flowing liquid. Extraneous rust Rust not originating from the steel under consideration, e.g., rust brought to the site from a rusting iron object by means of a flowing liquid, or formed by rusting of iron particles brought to the steel surface.

General corrosion Corrosion taking place at about the same rate all over the surface affected by the corrosive medium. Huey test Corrosion testing in a boiling solution of nitric acid. This test is mainly used to detect the susceptibility to intergranular corrosion of stainless steel. Immunity A thermodynamically stable condition. Impingement corrosion See Erosion corrosion. Intercrystalline corrosion See Intergranular corrosion. Intergranular corrosion Corrosion at or near grain boundaries. Localised corrosion Corrosion taking place at a relatively high speed in limited sections of the area exposed to a corrosive medium. Cf. General corrosion. Localised attack See Localised corrosion. Mill scale A thick oxide coating formed on the steel when heated, e.g., in connection with hot working or heat treatment. Moneypenny-Strauss test Corrosion testing in a copper sulphate solution containing sulphuric acid. Used to detect the susceptibility to intergranular corrosion of stainless steel. Oxidising agents Agents that are highly oxidising, e.g. Fe3+, O2, Cl2 or NO3–, and can facilitate local attack if e.g. chlorides are present, but may be favourable in reducing solutions. Passivation Changing steel from active to the passive condition. Passivation potential The electrode potential at which steel is converted from the active to the passive condition. Passivity A condition, in which the anodic dissolution of a steel is strongly reduced by, e.g., a thin oxide film. Passivity impedes the corrosion of steel.

Pickling bath Solution used for pickling. The pickling bath is normally composed of acids, but can in electrolytic pickling consist of salt solution. Pit A corroded hollow in a metal surface, caused by localised corrosion (pitting). Pitting Localised corrosion causing attacks over small surface areas but reaching considerable depths. Pitting potential The electrode potential, above which there is a risk of pitting. The value of the pitting potential varies depending on testing conditions. Redox potential A measure of the oxidising ability of a solution. A solution having a high redox potential has a high oxidising ability. Scaling temperature The temperature, above which steel oxidises at a high rate. Selective corrosion Corrosion characterised by single alloying components or phases being dissolved faster than the general body of the steel. Sensitising A heat treatment that makes steel more sensitive to intergranular corrosion. Stabilisation An addition of titanium or niobium, making stainless steels less sensitive to intergranular corrosion. Stray current corrosion Electrochemical corrosion caused by stray currents leaking from an electrical installation. Stress corrosion cracking Formation of cracks caused by the action of a corrosive medium, such as a chloridic solution, in combination with tensile stress. Stress relieving Heat treatment carried out in order to reduce internal stresses in steel. U-bend specimen Horseshoe-shaped test piece used to detect the susceptibility of a material to stress corrosion cracking.

Pickling A chemical or electrochemical method of removing mill scale, rust and similar coatings from steel. Pickle See Pickling bath.

II:87

kupdf.com_corrosion-handbook-on-stainless-steel.pdf

Recommend Documents