ASTM G87-02(2013)
(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 and health practices and determine the applicability of regulatory limitations prior to use. For a specific warning statement, see 4.3.
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Designation: G87 − 02 (Reapproved 2013)
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.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope G1 Practice for Preparing, Cleaning, and Evaluating Corro-
sion Test Specimens
1.1 This practice covers the apparatus and procedure to be
G46 Guide for Examination and Evaluation of Pitting Cor-
used in conducting qualitative assessment tests in accordance
rosion
with the requirements of material or product specifications by
means of specimen exposure to condensed moisture containing
3. Significance and Use
sulfur dioxide.
3.1 Moist air containing sulfur dioxide quickly produces
1.2 The exposure conditions may be varied to suit particular
easily visible corrosion on many metals in a form resembling
requirements and this practice includes provisions for use of
that occurring in industrial environments. It is therefore a test
different concentrations of sulfur dioxide and for tests either
medium well suited to detect pores or other sources of
running continuously or in cycles of alternate exposure to the
weakness in protective coatings and deficiencies in corrosion
sulfur dioxide containing atmosphere and to the ambient
resistance associated with unsuitable alloy composition or
atmosphere.
treatments.
1.3 The variant of the test to be used, the exposure period
3.2 Theresultsobtainedinthetestshouldnotberegardedas
required, the type of test specimen, and the criteria of failure
a general guide to the corrosion resistance of the tested
are not prescribed by this practice. Such details are provided in
materials in all environments where these materials may be
appropriate material and product purchase specifications.
used. Performance of different materials in the test should only
1.4 The values stated in SI units are to be regarded as be taken as a general guide to the relative corrosion resistance
standard. The values given in parentheses are for information
of these materials in moist SO service.
only.
4. Apparatus
1.5 This standard does not purport to address all of the
4.1 The apparatus required for moist SO testing consists of
safety concerns, if any associated with its use. It is the 2
a test chamber having an internal capacity of 300 L (10.6 ft ),
responsibility of the user of this standard to establish appro-
a supply of sulfur dioxide with metering device, specimen
priate safety and health practices and determine the applica-
supports, provisions for heating the chamber, and necessary
bility of regulatory limitations prior to use. For a specific
means of control. The size and detailed construction of the
warning statement, see 4.3.
apparatus are optional, provided the conditions obtained meet
2. Referenced Documents
therequirementsofthispractice.Suitableapparatuswhichmay
beusedtoobtaintheseconditionsisdescribedinAppendixX1.
2.1 ASTM Standards:
D714 Test Method for Evaluating Degree of Blistering of
4.2 Drops of condensing moisture which accumulate on the
Paints
ceiling of the chamber shall not be permitted to fall on the
D1193 Specification for Reagent Water
specimens being tested.
D1654 Test Method for Evaluation of Painted or Coated
4.3 (Warning—Suck-back into cylinder may cause explo-
Specimens Subjected to Corrosive Environments
sion. Always use a check valve, vacuum break, or other
protective apparatus in any line or piping from cylinder to test
This practice is under the jurisdiction of ASTM Committee G01 on Corrosion chamber to prevent suck-back. Installation of the chamber
of Metals and is the direct responsibility of Subcommittee G01.05 on Laboratory
under a fume hood is recommended.)
Corrosion Tests.
CurrenteditionapprovedMay1,2013.PublishedJuly2013.Originallyapproved
5. Reagents
in 1997. Last previous edition approved in 2007 as G87-02 (2007). DOI:
10.1520/G0087-02R13.
5.1 Purity of Reagents—Reagent grade chemicals shall be
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
used in all tests. Unless otherwise indicated, it is intended that
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
all reagents shall conform to the specifications of the Commit-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. tee onAnalytical Reagents of theAmerican Chemical Society,
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G87 − 02 (2013)
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
with a suitable medium, stable under the conditions of the test,
5.2 Purity of Water—Unless otherwise indicated, references
such as wax or tape. High-quality platers tape or microcrystal-
to water shall be understood to mean reagent water as defined
line wax are generally suitable.
by Type IV of Specification D1193.
7.5 Position of Specimens During Test:
5.3 A commercially available source of bottled SO gas
7.5.1 Place the test specimens in the cabinet so that no part
having a minimum purity of 99.9 % (liquid phase) with proper
ofanyspecimeniswithin20mm(0.78in.)ofanotherorwithin
regulator, and means of measuring the volumes of gas required
100 mm (3.93) of the walls or the ceiling or within 200 mm
for delivery into test chamber shall be provided.
(7.87in.)ofthesurfaceofthewaterinthebaseofthechamber.
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(122
chaser and supplier (see 7.1).
in. ) of sulfur dioxide before it is brought into use for testing.
This should reduce any risks of contamination of the atmo-
7. Test Specimens
sphere 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 6 0.2 L (122 in. 6 12 in. ) of distilled
purchaser and supplier.
water into the base of chamber.
7.2 The total combined exposed surface area of the material
9.2 Place the test specimens in the chamber and close the
tested at any one time should be substantially the same and
2 2 door/lid.
unless otherwise agreed upon, it shall be 0.5 6 0.1 m (5.4 ft
61ft ). 9.3 Introduce the volume of sulfur dioxide, required by the
7.2.1 Morespecimensofthesamematerialmaybeadded,if governingmaterialsspecification,intothechamberthroughthe
needed. inlet pipe. Usually this volume will be 0.2, 1, or 2 L (12 in. ,
3 3 3
61 in. , or 122 in. 6 12 in. ).
7.3 To obtain quantitative corrosion-rate data, only materi-
als with similar reactivities should be included in a test run.
9.4 Switchontheheaterandraisethetemperatureinsidethe
chamber to 40 6 3°C (104 6 5.4°F) in about 1.5 h. Make sure
7.4 Preparation of Test Specimens:
the heating is under control to keep the temperature inside the
7.4.1 Suitably clean the specimens before testing (see Prac-
chamber at 40 6 3°C (104 6 5.4°F) for the specified period.
tice G1). Unless otherwise agreed upon the cleaning method
Each set point and its tolerance represents an operational
shall be optional depending on the nature of the surface and of
control point for equilibrium conditions at a single location in
the likelihood of contamination.The cleaning method shall not
the cabinet which may not necessarily represent the uniformity
include the use of abrasives (other than a paste of pure
of conditions throughout the cabinet.
magnesium oxide), corrosive solvents, corrosion-promoting
materials or protective film formers. Care in handling is
9.5 One test cycle is 24 h. Either Method A or B, and the
necessary so as not to recontaminate the test specimens.
number of cycles shall be designated by the specification for
thematerialorproductbeingtestedormutuallyagreeduponby
thepurchaserandseller.Foreithermethod,replacethewaterin
the chamber and the sulfur dioxide in the air of the chamber
Reagent Chemicals, American Chemical Society Specifications , American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
before each 24 h cycle begins.
listed by the American Chemical Society, see Analar Standards for Laboratory U.
9.5.1 Method A, Continuous Exposure—The specimens
K. Chemicals, BDH Ltd., Poole, Dorset, and the United States Pharmacopeia and
shall remain co
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