ASTM G87-02(2023)
(Practice)Standard Practice for Conducting Moist SO2 Tests
Standard Practice for Conducting Moist SO<inf>2</inf> Tests
SIGNIFICANCE AND USE
3.1 Moist air containing sulfur dioxide quickly produces easily visible corrosion on many metals in a form resembling that occurring in industrial environments. It is therefore a test medium well suited to detect pores or other sources of weakness in protective coatings and deficiencies in corrosion resistance associated with unsuitable alloy composition or treatments.
3.2 The results obtained in the test should not be regarded as a general guide to the corrosion resistance of the tested materials in all environments where these materials may be used. Performance of different materials in the test should only be taken as a general guide to the relative corrosion resistance of these materials in moist SO2 service.
SCOPE
1.1 This practice covers the apparatus and procedure to be used in conducting qualitative assessment tests in accordance with the requirements of material or product specifications by means of specimen exposure to condensed moisture containing sulfur dioxide.
1.2 The exposure conditions may be varied to suit particular requirements and this practice includes provisions for use of different concentrations of sulfur dioxide and for tests either running continuously or in cycles of alternate exposure to the sulfur dioxide containing atmosphere and to the ambient atmosphere.
1.3 The variant of the test to be used, the exposure period required, the type of test specimen, and the criteria of failure are not prescribed by this practice. Such details are provided in appropriate material and product purchase specifications.
1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.
1.5 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 determine the applicability of regulatory limitations prior to use. For a specific warning statement, see 4.3.
1.6 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: G87 − 02 (Reapproved 2023)
Standard Practice for
Conducting Moist SO Tests
This standard is issued under the fixed designation G87; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This practice covers the apparatus and procedure to be 2.1 ASTM Standards:
used in conducting qualitative assessment tests in accordance D714 Test Method for Evaluating Degree of Blistering of
with the requirements of material or product specifications by Paints
means of specimen exposure to condensed moisture containing D1193 Specification for Reagent Water
sulfur dioxide. D1654 Test Method for Evaluation of Painted or Coated
Specimens Subjected to Corrosive Environments
1.2 The exposure conditions may be varied to suit particular
G1 Practice for Preparing, Cleaning, and Evaluating Corro-
requirements and this practice includes provisions for use of
sion Test Specimens
different concentrations of sulfur dioxide and for tests either
G46 Guide for Examination and Evaluation of Pitting Cor-
running continuously or in cycles of alternate exposure to the
rosion
sulfur dioxide containing atmosphere and to the ambient
atmosphere.
3. Significance and Use
1.3 The variant of the test to be used, the exposure period
3.1 Moist air containing sulfur dioxide quickly produces
required, the type of test specimen, and the criteria of failure
easily visible corrosion on many metals in a form resembling
are not prescribed by this practice. Such details are provided in
that occurring in industrial environments. It is therefore a test
appropriate material and product purchase specifications.
medium well suited to detect pores or other sources of
1.4 The values stated in SI units are to be regarded as weakness in protective coatings and deficiencies in corrosion
standard. The values given in parentheses are for information resistance associated with unsuitable alloy composition or
only. treatments.
1.5 This standard does not purport to address all of the
3.2 The results obtained in the test should not be regarded as
safety concerns, if any, associated with its use. It is the
a general guide to the corrosion resistance of the tested
responsibility of the user of this standard to establish appro-
materials in all environments where these materials may be
priate safety, health, and environmental practices and deter-
used. Performance of different materials in the test should only
mine the applicability of regulatory limitations prior to use.
be taken as a general guide to the relative corrosion resistance
For a specific warning statement, see 4.3.
of these materials in moist SO service.
1.6 This international standard was developed in accor-
4. Apparatus
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
4.1 The apparatus required for moist SO testing consists of
Development of International Standards, Guides and Recom-
a test chamber having an internal capacity of 300 L (10.6 ft ),
mendations issued by the World Trade Organization Technical
a supply of sulfur dioxide with metering device, specimen
Barriers to Trade (TBT) Committee.
supports, provisions for heating the chamber, and necessary
means of control. The size and detailed construction of the
apparatus are optional, provided the conditions obtained meet
This practice is under the jurisdiction of ASTM Committee G01 on Corrosion
of Metals and is the direct responsibility of Subcommittee G01.05 on Laboratory
Corrosion Tests. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved June 1, 2023. Published June 2023. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1997. Last previous edition approved in 2018 as G87 – 02 (2018). DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/G0087-02R23. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G87 − 02 (2023)
the requirements of this practice. Suitable apparatus which may 7.2 The total combined exposed surface area of the material
be used to obtain these conditions is described in Appendix X1. tested at any one time should be substantially the same and
2 2
unless otherwise agreed upon, it shall be 0.5 m 6 0.1 m
4.2 Drops of condensing moisture which accumulate on the 2
(5.4 ft 6 1 ft ).
ceiling of the chamber shall not be permitted to fall on the
7.2.1 More specimens of the same material may be added, if
specimens being tested.
needed.
4.3 (Warning—Suck-back into cylinder may cause explo-
7.3 To obtain quantitative corrosion-rate data, only materi-
sion. Always use a check valve, vacuum break, or other
als with similar reactivities should be included in a test run.
protective apparatus in any line or piping from cylinder to test
7.4 Preparation of Test Specimens:
chamber to prevent suck-back. Installation of the chamber
under a fume hood is recommended.) 7.4.1 Suitably clean the specimens before testing (see Prac-
tice G1). Unless otherwise agreed upon, the cleaning method
shall be optional depending on the nature of the surface and of
5. Reagents
the likelihood of contamination. The cleaning method shall not
5.1 Purity of Reagents—Reagent grade chemicals shall be
include the use of abrasives (other than a paste of pure
used in all tests. Unless otherwise indicated, it is intended that
magnesium oxide), corrosive solvents, corrosion-promoting
all reagents shall conform to the specifications of the Commit-
materials, or protective film formers. Care in handling is
tee on Analytical Reagents of the American Chemical Society,
necessary so as not to recontaminate the test specimens.
where such specifications are available. Other grades may be
7.4.2 If test specimens are cut from a larger coated article,
used, provided it is first ascertained that the reagent is of
carry out the cutting in such a way that coating damage is
sufficiently high purity to permit its use without lessening the
minimized in the area adjacent to the cut. Unless otherwise
accuracy of the determination.
specified, adequately protect the cut edges by coating them
5.2 Purity of Water—Unless otherwise indicated, references
with a suitable medium, stable under the conditions of the test,
to water shall be understood to mean reagent water as defined
such as wax or tape. High-quality platers tape or microcrystal-
by Type IV of Specification D1193.
line wax are generally suitable.
5.3 A commercially available source of bottled SO gas 7.5 Position of Specimens During Test:
having a minimum purity of 99.9 % (liquid phase) with proper
7.5.1 Place the test specimens in the cabinet so that no part
regulator, and means of measuring the volumes of gas required
of any specimen is within 20 mm (0.78 in.) of another or within
for delivery into test chamber shall be provided.
100 mm (3.93) of the walls or the ceiling or within 200 mm
(7.87 in.) of the surface of the water in the base of the chamber.
5.4 The volume of gas delivered into test chamber shall be
7.5.2 Arrange the specimens so that moisture which may
measured by means of either a properly calibrated flowmeter
condense on any of them or their supports will not fall on other
(rotameter type) with metering valve, or in a gas buret using
specimens placed at lower levels. If possible, place all test
viscous paraffin oil as the pressure controlling fluid.
specimens on the same horizontal plane so they are exposed to
5.4.1 The volume to be measured may be as small as 0.2 L.
equal concentrations of SO gas.
Measures should be taken to avoid errors from air contained in
7.5.3 Unless otherwise agreed upon, the angle of inclination
delivery tubes between flowmeter or gas burette and test
of test surfaces to the vertical is optional. A near vertical
chamber.
orientation (0 to 10° from vertical) is suggested unless other-
wise agreed upon or specified.
6. Sampling
6.1 The specific location of samples in a mill product, the
8. Conditioning
number of samples that should be tested, and other factors
8.1 Operate a new chamber for at least ten 24 h cycles
concerning sampling, are not within the scope of this practice.
without introduction of any test material by the procedure
These factors should be mutually agreed upon between pur-
applicable to an atmosphere containing an addition of 2 L
chaser and supplier (see 7.1).
(122 in. ) of sulfur dioxide before it is brought into use for
testing. This should reduce any risks of contamination of the
7. Test Specimens
atmosphere by vapors from construction materials of chamber.
7.1 Select the number and type of test specimens, and their
shape and dimensions according to the specification covering
9. Procedure
the product or material being tested or agreed upon between
3 3
9.1 Introduce 2 L 6 0.2 L (122 in. 6 12 in. ) of distilled
purchaser and supplier.
water into the base of chamber.
9.2 Place the test specimens in the chamber and close the
door/lid.
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
Standard-Grade Reference Materials, American Chemical Society, Washington,
9.3 Introduce the volume of sulfur dioxide, required by the
DC. For suggestions on the testing of reagents not listed by the American Chemical
governing materials specification, into the chamber through the
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
inlet pipe. Usually this volume will be 0.2 L, 1 L, or 2 L
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
3 3 3 3
copeial Convention, Inc. (USPC), Rockville, MD. (12 in. , 61 in. , or 122 in. 6 12 in. ).
G87 − 02 (2023)
9.4 Switch on the heater and raise the temperature inside the specification for the material or product tested. For most
chamber to 40 °C 6 3 °C (104 °F 6 5.4 °F) in about 1.5 h. routine applications of the test, only the following need to be
Make sure the heating is under control to keep the temperature considered:
inside the chamber at 40 °C 6 3 °C (104 °F 6 5.4 °F) for the 10.1.1 Appearance after drying in air,
specified period. Each set point and its toleranc
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