ASTM G92-20

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
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: G92 − 86 (Reapproved 2015) G92 − 20
Standard Practice for
Characterization of Atmospheric Test Sites
This standard is issued under the fixed designation G92; 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 gives suggested covers procedures for the characterization of atmospheric test sites. Continuous characterization
can provide corrosion data, environmental data, or both which will signal changes in corrosivity of the atmospheric environment.
This practice can also provide guidance for classification of future test sites.
1.2 Two methods are defined in this practice for the characterization of atmospheric test sites. The methods are identified as
characterization Methods A and B. The preferred characterization technique would require using both Method A and B for
concurrent data collection.
1.2.1 Method A is to be used when atmospheric corrosion is monitored on a continuing basis at a test site using specified materials
and exposure configurations.
1.2.2 Method B is specified when atmospheric factors are monitored on a continuing basis.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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.
1.5 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:
A36/A36M Specification for Carbon Structural Steel
B6 Specification for Zinc
G1 Practice for Preparing, Cleaning, and Evaluating Corrosion Test Specimens
G50 Practice for Conducting Atmospheric Corrosion Tests on Metals
G84 Practice for Measurement of Time-of-Wetness on Surfaces Exposed to Wetting Conditions as in Atmospheric Corrosion
Testing
G91 Practice for Monitoring Atmospheric SO Deposition Rate for Atmospheric Corrosivity Evaluation
This practice is under the jurisdiction of ASTM Committee G01 on Corrosion of Metals and is the direct responsibility of Subcommittee G01.04 on Atmospheric
CorrosionCorrosion of Metals in Natural Atmospheric and Aqueous Environments.
Current edition approved Nov. 1, 2015Nov. 1, 2020. Published December 2015November 2020. Last previous edition approved in 20102015 as
G92–86(2010).G92–86(2015). DOI: 10.1520/G0092-86R15. 10.1520/G0092-20.
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’sstandard’s Document Summary page on the ASTM website.
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G92 − 20
3. Summary of Methods
3.1 Characterization Method A is to be used when atmospheric corrosion data are to be obtained.
3.1.1 Corrosion tests to measure the corrosivity of the test site should follow the procedure established by Practice G50. Additional
special instructions are identified in this procedure relating to types of materials for corrosion characterization tests, time of test
exposure, positioning of test specimens, removal of test specimens and proper identification, cleaning practices, and reporting of
data.
3.2 Characterization Method B is to be used when atmospheric climatological factors influencing the corrosion of metals are to
be monitored.
3.2.1 Several atmospheric factors which have been identified as having significant bearing on the corrosion of metals include, but
are not limited to, sulfur dioxide, chlorides, temperature, humidity, precipitation, time of wetness, and atmospheric particulate
matter.
3.3 The preferred technique utilizes both Methods A and B for concurrent data to be collected.
3.3.1 Should either Method A or B be singled out as the primary technique to be used on a continuing basis, both should be used
at some point in time to establish a data base. The availability of computerized weather stations greatly facilitates the collection
of reliable atmospheric data.
4. Significance and Use
4.1 This practice gives suggested procedures for characterization of atmospheric test sites. It can be useful to researchers,
manufacturers, engineering firms, architects, and construction contractors to provide corrosion and environmental data, materials
selection information, and a materials storage practice.
4.2 This practice does not give specific parameters for classifying the type of test site.
PROCEDURES
5. Method A
5.1 Materials:
5.1.1 The materials recommended for conducting atmospheric corrosion characterization studies are copper-bearing structural
carbon steel (such as Specification A36/A36M with 0.2 % copper min) and high-purity zinc (Specification B6 high grade).
5.1.2 Materials recommended are the absolute minimum required to serve as a characterization base for test sites. Additional
materials should be added to meet individual needs. Sufficient material should be obtained at the start to insure that an ample supply
of the same heat is available to complete the characterization test. If tests are on-going and additional materials must be obtained,
care should be taken in attempting to match material compositions.
5.1.3 Sufficient specimens should be prepared to comply with the specific criteria for the planned characterization test.
5.2 Material Preparation:
5.2.1 Test specimens should be sheared to size, for example, 100 × 150Atmospheric test specimens, as shown for example, in Fig.
1mm., shall be cut and finished in a manner that will not detrimentally affect the corrosion behavior of exposed edges.
NOTE 1—Shearing may not be practical for some material section thicknesses, and may introduce stresses and microcrevices that may accelerate edge
attack if not further machined.
5.2.2 An identifying code should be assigned to each specimen. Locating a permanent code on each test specimen can be
accomplished easily by using a code template (Fig. 1).
G92 − 20
* Template contains 126 drilled holes
FIG. 1 Sample Atmospheric Specimen Drill Code Identification Template
5.2.2.1 Pre-assignment of codes for a definite test period is suggested. After a temporary mark is placed on the specimen, a
permanent drilled code (a series of 2.5 mm holes) should perforate the test specimen.
5.2.3 All test specimens of the same alloy should be cleaned by the same procedure to ensure a comparative surface finish
following the guidance of Practice G1. The recommended practice suggested for cleaning is (a) degrease and pickle, if necessary,
to remove grease, mill scale, or other impurities; (b) scrub with pumice and britle only a natural fiber or synthetic fiber bristle brush
until free of water-break; (c) dry with towels; and (d) place in a desiccator for 2 h before weighing.
5.2.4 Specimens should be weighed (61.0 mg) and original mass recorded on a data sheet (Table 1). Specific information, such
as nominal composition, density, and exposed area should also be recorded.
5.2.5 Specimens should be stored in a desiccator or sealed in airtight storage bags until the time of exposure.
5.3 Exposure of Test Specimens:
5.3.1 The frequency at which test specimens should be exposed at a test site is dictated by the specific needs for data.
5.3.2 Triplicate specimens of each material should be exposed for each test period.
5.3.3 An exposure period of one year is suggested as a minimum, multiple periods should be considered, for example, 3, 6, and
12 months; 1 and 2 years or 1, 2, and 4 years. Shorter test periods may be necessary where corrosion is severe and longer test
periods where corrosion is less severe.
G92 − 20
TABLE 1 Sample Data Sheet for Atmospheric Corrosion Data
Test Site: Kure Beach (250 m lot) Latitude: 34° 00' N
Exposure Dates: 10/7/61 to 10/6/62 Longitude: 77° 55' W
Mass (g)
Material Code Exposure Period Mass Loss Per Corrosion
(days) Original Final Loss Unit Area Rate
(mg/m ) (mm/y)
Cu-steel A1-B2 365 196.583 187.332 9.251 2.86 × 10 0.0365
Zinc A2-B2 365 67.521 66.938 0.583 1.84 × 10 0.0026
Test Method Documentation
Steel Zinc
1. Composition (weight %) 0.15 C, 1.0 Mn, 0.01 P, 0.027 S, 0.24 Si, 0.01 Cu, 0.012 Cd, 0.03 Pb, 0.02 Fe,
0.21 Cu, 0.05 Ni, 0.03 Cr, Balance Fe Balance Zn
3 3 3
2. Density (g/cm ) 7.85 g/cm 7.13 g/cm
3. Dimensions (mm) 100 × 150 × 2.00 mm 100 × 150 × 2.00 mm
3. Dimensions (mm) 100 mm × 150 mm × 2.00 mm 100 mm × 150 mm × 2.00 mm
2 2 2
4. Exposed area (cm ) 322.9 cm 317.7 cm
TABLE 2 Sample Data Sheet for Atmospheric Climatological Data
Test Site: Kure Beach (250 m lot) Latitude: 34° 00' N
Dates: 5/1/83 to 5/3/83 Longitude: 77° 55' W
Time of Wetness
Temperature (°C) Relative Humidity (%)
Precipitation
(h/day)
Date
(mm)
High Low Mean High Lo
...