ASTM G157-98(2018)
(Guide)Standard Guide for Evaluating Corrosion Properties of Wrought Iron- and Nickel-Based Corrosion Resistant Alloys for Chemical Process Industries
Standard Guide for Evaluating Corrosion Properties of Wrought Iron- and Nickel-Based Corrosion Resistant Alloys for Chemical Process Industries
SIGNIFICANCE AND USE
4.1 This guide is intended to provide a series of evaluations that will assist engineers dealing with chemical environments in selecting appropriate alloys (1-3). In chemical environments, an important issue for determining general corrosion resistance is the temperature at which an alloy transitions from corrosion at a low rate to corrosion at a much higher rate. Other important concerns include the tendency towards crevice corrosion and stress corrosion cracking resistance, especially in hot chloride-containing aqueous environments.
4.2 This guide is also intended for alloy developers to assist them in choosing environments and test methods that are of particular interest to the chemical process industries.
4.3 The use of this approach will allow direct comparisons to be made among alloys from various suppliers and, thereby, to assist engineers in selecting the most appropriate materials for further testing to determine suitability in their application.
SCOPE
1.1 This guide covers an evaluation approach that is designed to provide information on the corrosion properties of wrought iron- and nickel-based alloys for the chemical process industries. This guide incorporates test conditions for general corrosion measurements in a variety of environments, crevice corrosion resistance in chloride environments, and stress corrosion cracking resistance in chloride environments.
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and to determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: G157 − 98 (Reapproved 2018)
Standard Guide for
Evaluating Corrosion Properties of Wrought Iron- and
Nickel-Based Corrosion Resistant Alloys for Chemical
Process Industries
This standard is issued under the fixed designation G157; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope ing (Withdrawn 2010)
G30 Practice for Making and Using U-Bend Stress-
1.1 This guide covers an evaluation approach that is de-
Corrosion Test Specimens
signed to provide information on the corrosion properties of
G36Practice for Evaluating Stress-Corrosion-Cracking Re-
wroughtiron-andnickel-basedalloysforthechemicalprocess
sistance of Metals and Alloys in a Boiling Magnesium
industries. This guide incorporates test conditions for general
Chloride Solution
corrosion measurements in a variety of environments, crevice
G46Guide for Examination and Evaluation of Pitting Cor-
corrosion resistance in chloride environments, and stress cor-
rosion
rosion cracking resistance in chloride environments.
G48Test Methods for Pitting and Crevice Corrosion Resis-
1.2 The values stated in SI units are to be regarded as
tance of Stainless Steels and Related Alloys by Use of
standard. The values given in parentheses are for information
Ferric Chloride Solution
only.
G123TestMethodforEvaluatingStress-CorrosionCracking
1.3 This standard does not purport to address all of the
of Stainless Alloys with Different Nickel Content in
safety concerns, if any, associated with its use. It is the Boiling Acidified Sodium Chloride Solution
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and to 3. Terminology
determine the applicability of regulatory limitations prior to
3.1 Terms such as crevice corrosion, stress corrosion
use.
cracking, and corrosion rate are defined in Terminology G15.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
4. Significance and Use
ization established in the Decision on Principles for the
4.1 This guide is intended to provide a series of evaluations
Development of International Standards, Guides and Recom-
that will assist engineers dealing with chemical environments
mendations issued by the World Trade Organization Technical
inselectingappropriatealloys(1-3).Inchemicalenvironments,
Barriers to Trade (TBT) Committee.
animportantissuefordetermininggeneralcorrosionresistance
is the temperature at which an alloy transitions from corrosion
2. Referenced Documents
at a low rate to corrosion at a much higher rate. Other
2.1 ASTM Standards:
important concerns include the tendency towards crevice
D1193Specification for Reagent Water
corrosionandstresscorrosioncrackingresistance,especiallyin
G1Practice for Preparing, Cleaning, and Evaluating Corro-
hot chloride-containing aqueous environments.
sion Test Specimens
4.2 Thisguideisalsointendedforalloydeveloperstoassist
G15TerminologyRelatingtoCorrosionandCorrosionTest-
them in choosing environments and test methods that are of
particular interest to the chemical process industries.
4.3 The use of this approach will allow direct comparisons
This guide is under the jurisdiction ofASTM Committee G01 on Corrosion of
Metals and is the direct responsibility of Subcommittee G01.05 on Laboratory
to be made among alloys from various suppliers and, thereby,
Corrosion Tests.
to assist engineers in selecting the most appropriate materials
Current edition approved Oct. 1, 2018. Published November 2018. Originally
for further testing to determine suitability in their application.
approved in 1998. Last previous edition approved in 2013 as G157–98 (2013).
DOI: 10.1520/G0157-98R18.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G157 − 98 (2018)
5. General Corrosion Resistance
5.1 The general corrosion resistance of nickel- and iron-
based alloys is determined in 14 test solutions at various
temperatures to determine the lowest temperature at which the
corrosion rate exceeds 0.13 mm/y (5 mpy). The test solutions
are listed in Table 1. A suggested procedure is provided in
Appendix X1. The test is run on three coupons of metal for
each environment. The tests are run for two 48-h exposures
with one specimen exposed for the total 96 h. Welded speci-
mens may be used if results are required on weldments.
5.2 The corrosion rates are based on mass loss measure-
ments with appropriate conversion to thickness loss as shown
in Appendix X1.
FIG. 1 Summary Results Form - Alloy Description
5.3 The results of the tests in each solution should be
reportedonasummaryresultssheet.Atypicalformatisshown
in Fig. 1 and Fig. 2.
6. Six Percent Ferric Chloride Solution Critical Crevice
Corrosion Temperature
6.1 The crevice corrosion resistance of each alloy is to be
evaluated as described in Test Methods G48, Method D. The
standard exposure period of 72 h is to be used. Mass loss
resultsarealsotobeobtainedandreportedinthisenvironment.
6.2 The results of this test are to be reported as discussed in
Test Methods G48. The results should also be entered on the
summary results sheet shown in Fig. 3.
7. Chloride Stress Corrosion Resistance
7.1 Theresistancetochloridestresscorrosioncrackingisan
important characteristic of alloys used in the chemical process
industries. Two environments are provided to evaluate and
FIG. 2 Summary Results Form - General Corrosion Resistance
report chloride stress corrosion cracking behavior—acidified
sodium chloride and magnesium chloride. The magnesium
Test Method G123 should be used, if possible. This design is
chloride environment is highly acidic and, as a consequence,
based on the Practice G30 U-bend and the tests should be
tends to cause many suitably resistant alloys to fail. The
carried out with at least triplicate specimens for a period of
acidified sodium chloride environment gives results closer to
1000 h. The results are to be reported as described in Test
experience in cooling water and process water environments.
Method G123 and entered on the summary results sheet. See
7.2 Acidified Sodium Chloride Test—Test Method G123
Fig. 3.
should be used to evaluate all alloys for resistance to chloride
7.3 Magnesium Chloride Test, Optional—Alloys that do not
stress corrosion cracking. The specimen design suggested in
crack in the acidified sodium chloride environment may be
tested in a magnesium chloride test. The test environment is
TABLE 1 Fourteen Environments for Evaluating General
described in Practice G36. U-bend specimens similar to those
Corrosion Resistance
suggested in Test Method G123 should be used with triplicate
A
Corrodent Formula Concentration, %
replication.Thetestshouldberunfor30daysoruntilcracking
Hydrochloric Acid HCl 0.2, 1.0, 5.0
B is observed. The specimens should be removed at convenient
Sulfuric Acid H SO 10, 60, 96
2 4
B
Nitric Acid HNO 10, 70 intervals not to exceed three days during exposure and exam-
B
Phosphoric Acid H PO 85
3 4
ined for cracking. The time to first crack is reported. Metallo-
Formic Acid HCOOH 50
graphic sectioning is to be carried out on at least one of each
Acetic Acid CH COOH 80
Sodium Hydroxide NaOH 50
set of replicates at the end of the exposure to document the
C
Hydrochloric Acid + HCl + FeCl 1.0 HCl + 0.3 FeCl
3 3
crack morphology or, in the case of surviving specimens, that
Ferric Chloride
no microcracks are present. The result of this test is to be
Acetic Acid + CH COOH + (CH CO) O 50/50
3 3 2
Acetic Anhydride
reported on the summary results sheet (Fig. 3).
A
All chemicals are ACS reagent grade mixed with Specification D1193 Type 4
8. Report
reagent water.
B
Undiluted reagent grade acid may be used.
C 8.1 The results of these tests are to be reported as specified
Ferric chloride concentration calculated on anhydrous basis.
in the test method referenced. The summary results sheets
G157 − 98 (2018)
shown in Figs. 1-3 provide a convenient form to present the
results in a consistent format.
9. Keywords
9.1 chemical process industry; crevice corrosion; general
corrosion; iron-base corrosion resistant alloys; nickel-base
corrosion resistant alloys; stress corrosion cracking
FIG. 3 Summary Results Form - Localized Corrosion Perfor-
mance
APPENDIX
(Nonmandatory Information)
X1. SUGGESTED LABORATORY TESTING OF IRON- AND NICKEL-BASED ALLOYS FOR CORROSION RESISTANCE IN
SELECTED MEDIA FOR GENERAL CORROSION PERFORMANCE
X1.1 Scope X1.2.2 AllcomponentsoftheapparatusdescribedinX1.2.1
which are in contact with the test environment (liquid and gas
X1.1.1 Thistestmethoddescribesasuggestedprocedurefor
phases) are to be made of glass or polytetrafluoroethylene
corrosion tests to determine the relative resistance of wrought
(PTFE) or other inert nonconductive material.
iron- and nickel-based alloys to corrosion in selected media.
X1.2.3 The temperature-regulating device used for tests at
These tests are intended to provide corrosion data suitable for
temperatures other than the boiling temperature should be
preliminary evaluation prior to testing for specific chemical
capable of controlling the temperature of the contents of the
applications.
flask to within 61°C of the selected test temperature.
X1.1.2 Each alloy is tested in the as-manufactured condi-
X1.2.4 The specimen support system should be designed so
tion;as-weldedspecimensmaybeincluded.(SeeX1.3.10.2for
that the specimen is separated from the flask and its internal
when only the as-welded condition need be tested.)
components. The specimen is to be maintained in a vertical
X1.1.3 Specimen evaluation procedures provide for mass position, totally immersed in the test solution. One desirable
loss measurements for evaluation of general corrosion and low support system is to use an individual glass cradle for each
specimen.
power surface microscopic examination for presence of local-
ized corrosion, such as pitting, stress corrosion, intergranular
X1.2.5 Anitrogen sparging system, which is used for initial
attack, end-grain corrosion, and preferential weld attack.
deaeration in tests at temperatures below boiling and in
non-oxidizing solutions, should be capable of sparging nitro-
X1.2 Apparatus
genattherateof100mL/min.Adevicetopreventbackflowof
test solution into the gas supply system should be included.
X1.2.1 A1000 mLErlenmeyer flask equipped with a reflux
condenser, a sparger with a fitted glass disc for deaerating
X1.3 Test Specimens
certain solutions, a specimen support system, and a means for
controlling the temperature of the contents of the flask are
X1.3.1 The specimens should be made from sheet, plate, or
recommended for all tests. strip produced by commercial methods.
G157 − 98 (2018)
X1.3.2 Materialfromwhichthespecimensaremadeshould X1.4 Test Solutions
be in the annealed condition, the final heat treatment being
X1.4.1 Test solution should be prepared accurately from
done after any cold rolling. Temperature of the final heat
reagent grade chemicals conforming to the Specifications of
treatment and method of cooling should be reported.
theCommitteeonAnalyticalReagentsoftheAmericanChemi-
X1.3.3 Thickness of the sheet materials used for specimens cal Society, and Specification D1193 Type IV reagent water.
should be between 1.5 and 4.8 mm (0.06 and 0.188 in.).Width
X1.4.2 The compositions of the various test solutions are
of the specimens should be 20 mm (0.8 in.) and the length 50
given in Table 1.
mm (2.0 in.).
X1.4.3 The sparging gas, employed to deaerate non-
X1.3.4 Specimens are to be cut to size by a machining
oxidizing solutions to be used in tests at temperatures below
operation.Ifshearedspecimensareused,theshearededgesare
the boiling point, should be nitrogen with a purity of at least
to be removed by grinding or machining; the amount of metal
99.9% and with an oxygen content of less than 0.02%.
removed by machining should equal the thickness of the
X1.4.4 Procedure for Preparing Solutions:
specimen.
X1.4.4.1 Hydrochloric Acid Solution—Use hydrochloric
X1.3.5 All specimens should be abraded to provide a
acid36.5to38%,specificgravity1.185to1.192.Prepare1200
uniformsurfacefinishfreeofscaleanddirt,andtoremoveany
mL of each solution using the volumes shown as follows:
sharp edges or burrs due to machining or drilling operations.
Desired % mL Concentrated HCl mL Reagent H O
The final step in this abrading operation should be done with
0.2 5.4 1197
wet No. 80 or dry No. 120 grit abrasive paper. Exercise care to
1.0 27.2 1184
5.0 139 1125
avoid overheating the surface. This step should be omitted
Add water to a 1.5 L beaker, then carefully and slowly add
when the intent of the test is to evaluate mill finish or other
the reagent acid to the beaker while stirring the mixture.When
surface conditions.
cool, measure 600 mL into each flask for the test.
X1.3.6 Specimens should be stamped with identifying let-
X1.4.4.2 Sulfuric Acid Solution—Use sulfuric acid 95 to
ters and numbers, using clean, hardened steel stamps.
98%, specific gravity 1.84 min. Prepare 800 mL of each
X1.3.7 Specimens should be measured prior to test and the
solution using volumes shown as follows:
total exposed area, including edges, calculated and reported to
Desired % mL Concentrated Acid mL Reagent H O
2 2
the closest 65 mm (0.1 in. ).
10 72 1148
60 608 680
X1.3.8 Following the abrasive treatment, the specimens
Add water to a 1.5 L beaker, then carefully and slowly add
should be cleaned with a magnesium oxide paste or detergent
concentrated acid to flask with constant stirring. In the case of
solution to remove any residual dirt or grease, rinsed in water,
the 60% solution, it is desirable to cool the mixture to 30°C
and dipped in acetone and air dried.
after about half of the acid has been added to avoid boiling.
X1.3.9 The dried specimens should be weighed to an
Then complete the acid addition.When cool, measure 600 mL
accuracy of at least 60.2 mg. Weighed specimens should be
i
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