ASTM G87-02(2018)

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it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: G87 − 02 (Reapproved 2013) G87 − 02 (Reapproved 2018)
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
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 safety, health, and healthenvironmental 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.
2. Referenced Documents
2.1 ASTM Standards:
D714 Test Method for Evaluating Degree of Blistering of Paints
D1193 Specification for Reagent Water
D1654 Test Method for Evaluation of Painted or Coated Specimens Subjected to Corrosive Environments
G1 Practice for Preparing, Cleaning, and Evaluating Corrosion Test Specimens
G46 Guide for Examination and Evaluation of Pitting Corrosion
3. 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 SO service.
4. Apparatus
4.1 The apparatus required for moist SO testing consists of a test chamber having an internal capacity of 300 L (10.6 ft ), a
supply of sulfur dioxide with metering device, specimen supports, provisions for heating the chamber, and necessary means of
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.
Current edition approved May 1, 2013Oct. 1, 2018. Published July 2013November 2018. Originally approved in 1997. Last previous edition approved in 20072013 as
G87G87 – 02 (2013).-02 (2007). DOI: 10.1520/G0087-02R13. 10.1520/G0087-02R18.
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 ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G87 − 02 (2018)
control. The size and detailed construction of the apparatus are optional, provided the conditions obtained meet the requirements
of this practice. Suitable apparatus which may be used to obtain these conditions is described in Appendix X1.
4.2 Drops of condensing moisture which accumulate on the ceiling of the chamber shall not be permitted to fall on the
specimens being tested.
4.3 (Warning—Suck-back into cylinder may cause explosion. Always use a check valve, vacuum break, or other protective
apparatus in any line or piping from cylinder to test chamber to prevent suck-back. Installation of the chamber under a fume hood
is recommended.)
5. Reagents
5.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where
such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use without lessening the accuracy of the determination.
5.2 Purity of Water—Unless otherwise indicated, references to water shall be understood to mean reagent water as defined by
Type IV of Specification D1193.
5.3 A commercially available source of bottled SO gas having a minimum purity of 99.9 % (liquid phase) with proper
regulator, and means of measuring the volumes of gas required for delivery into test chamber shall be provided.
5.4 The volume of gas delivered into test chamber shall be measured by means of either a properly calibrated flowmeter
(rotameter type) with metering valve, or in a gas buret using viscous paraffin oil as the pressure controlling fluid.
5.4.1 The volume to be measured may be as small as 0.2 L. Measures should be taken to avoid errors from air contained in
delivery tubes between flowmeter or gas burette and test chamber.
6. Sampling
6.1 The specific location of samples in a mill product, the number of samples that should be tested, and other factors concerning
sampling, are not within the scope of this practice. These factors should be mutually agreed upon between purchaser and supplier
(see 7.1).
7. Test Specimens
7.1 Select the number and type of test specimens, and their shape and dimensions according to the specification covering the
product or material being tested or agreed upon between purchaser and supplier.
7.2 The total combined exposed surface area of the material tested at any one time should be substantially the same and unless
2 2 2
otherwise agreed upon, it shall be 0.5 6 0.1 m (5.4 ft 6 1 ft ).
7.2.1 More specimens of the same material may be added, if needed.
7.3 To obtain quantitative corrosion-rate data, only materials with similar reactivities should be included in a test run.
7.4 Preparation of Test Specimens:
7.4.1 Suitably clean the specimens before testing (see Practice G1). Unless otherwise agreed upon the cleaning method shall
be optional depending on the nature of the surface and of the likelihood of contamination. The cleaning method shall not include
the use of abrasives (other than a paste of pure magnesium oxide), corrosive solvents, corrosion-promoting materials or protective
film formers. Care in handling is necessary so as not to recontaminate the test specimens.
7.4.2 If test specimens are cut from a larger coated article, carry out the cutting in such a way that coating damage is minimized
in the area adjacent to the cut. Unless otherwise specified, adequately protect the cut edges by coating them with a suitable medium,
stable under the conditions of the test, such as wax or tape. High-quality platers tape or microcrystalline wax are generally suitable.
7.5 Position of Specimens During Test:
7.5.1 Place the test specimens in the cabinet so that no part of any specimen is within 20 mm (0.78 in.) of another or within
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.
7.5.2 Arrange the specimens so that moisture which may condense on any of them or their supports will not fall on other
specimens placed at lower levels. If possible place all test specimens on the same horizontal plane so they are exposed to equal
concentrations of SO gas.
7.5.3 Unless otherwise agreed upon, the angle of inclination of test surfaces to the vertical is optional. A near vertical orientation
(0 to 10° from vertical) is suggested unless otherwise agreed upon or specified.
Reagent Chemicals, American Chemical Society Specifications, , American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by
the American Chemical Society, see Analar Standards for Laboratory U. K. Chemicals, BDH Ltd., Poole, Dorset, and the United States Pharmacopeia and National
Formulary, U.S. Pharamacopeial Convention, Inc. (USPC) Rockville, MD.”
G87 − 02 (2018)
8. Conditioning
8.1 Operate a new chamber for at least ten 24-h cycles without introduction of any test material by the procedure applicable
to an atmosphere containing an addition of 2 L (122 in. ) of sulfur dioxide before it is brought into use for testing. This should
reduce any risks of contamination of the atmosphere by vapors from construction materials of chamber.
9. Procedure
3 3
9.1 Introduce 2 6 0.2 L (122 in. 6 12 in. ) of distilled water into the base of chamber.
9.2 Place the test specimens in the chamber and close the door/lid.
9.3 Introduce the volume of sulfur dioxide, required by the governing materials specification, into the chamber through the inlet
3 3 3 3
pipe. Usually this volume will be 0.2, 1, or 2 L (12 in. , 61 in. , or 122 in. 6 12 in. ).
9.4 Switch on the heater and raise the temperature inside the chamber to 40 6 3°C (104 6 5.4°F) in about 1.5 h. Make sure
the heating is under control to keep the temperature inside the chamber at 40 6 3°C (104 6 5.4°F) for the specified period. Each
set point and its tolerance represents an operational control point for equilibrium conditions at a single location in the cabinet which
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