1、Designation: G92 86 (Reapproved 2010)Standard Practice forCharacterization of Atmospheric Test Sites1This standard is issued under the fixed designation G92; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision
2、. A number in parentheses indicates the year of last reapproval. A superscriptepsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice gives suggested procedures for the char-acterization of atmospheric test sites. Continuous characteriza-tion can prov
3、ide corrosion data, environmental data, or bothwhich will signal changes in corrosivity of the atmosphericenvironment. This practice can also provide guidance forclassification of future test sites.1.2 Two methods are defined in this practice for the char-acterization of atmospheric test sites. The
4、methods are identi-fied as characterization Methods A and B. The preferredcharacterization technique would require using both Method Aand B for concurrent data collection.1.2.1 Method A is to be used when atmospheric corrosion ismonitored on a continuing basis at a test site using specifiedmaterials
5、 and exposure configurations.1.2.2 Method B is specified when atmospheric factors aremonitored on a continuing basis.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesaf
6、ety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2A36/A36M Specification for Carb
7、on Structural SteelB6 Specification for ZincG1 Practice for Preparing, Cleaning, and Evaluating Corro-sion Test SpecimensG50 Practice for Conducting Atmospheric Corrosion Testson MetalsG84 Practice for Measurement of Time-of-Wetness on Sur-faces Exposed to Wetting Conditions as in AtmosphericCorrosi
8、on TestingG91 Practice for Monitoring Atmospheric SO2Using theSulfation Plate Technique3. Summary of Methods3.1 Characterization Method A is to be used when atmo-spheric corrosion data are to be obtained.3.1.1 Corrosion tests to measure the corrosivity of the testsite should follow the procedure est
9、ablished by Practice G50.Additional special instructions are identified in this procedurerelating to types of materials for corrosion characterizationtests, time of test exposure, positioning of test specimens,removal of test specimens and proper identification, cleaningpractices, and reporting of d
10、ata.3.2 Characterization Method B is to be used when atmo-spheric climatological factors influencing the corrosion ofmetals are to be monitored.3.2.1 Several atmospheric factors which have been identi-fied as having significant bearing on the corrosion of metalsinclude, but are not limited to, sulfu
11、r dioxide, chlorides,temperature, humidity, precipitation, time of wetness, andatmospheric particulate matter.3.3 The preferred technique utilizes both Methods A and Bfor concurrent data to be collected.3.3.1 Should either Method A or B be singled out as theprimary technique to be used on a continui
12、ng basis, bothshould be used at some point in time to establish a data base.The availability of computerized weather stations greatlyfacilitates the collection of reliable atmospheric data.4. Significance and Use4.1 This practice gives suggested procedures for character-ization of atmospheric test s
13、ites. It can be useful to researchers,manufacturers, engineering firms, architects, and constructioncontractors to provide corrosion and environmental data, ma-terials selection information, and a materials storage practice.4.2 This practice does not give specific parameters forclassifying the type
14、of test site.1This practice is under the jurisdiction of ASTM Committee G01 on Corrosionof Metals and is the direct responsibility of Subcommittee G01.04 on AtmosphericCorrosion.Current edition approved Sept. 1, 2010. Published May 2011. Last previousedition approved in 2003 as G9286(2003). DOI: 10.
15、1520/G0092-86R10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harb
16、or Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.PROCEDURES5. Method A5.1 Materials:5.1.1 The materials recommended for conducting atmo-spheric corrosion characterization studies are copper-bearingstructural carbon steel (such as Specification A36/A36M with0.2 % copper min) and
17、 high-purity zinc (Specification B6 highgrade).5.1.2 Materials recommended are the absolute minimumrequired 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 thatan ample supp
18、ly of the same heat is available to complete thecharacterization test. If tests are on-going and additionalmaterials must be obtained, care should be taken in attemptingto match material compositions.5.1.3 Sufficient specimens should be prepared to complywith the specific criteria for the planned ch
19、aracterization test.5.2 Material Preparation:5.2.1 Test specimens should be sheared to size, for example,100 3 150 mm.5.2.2 An identifying code should be assigned to eachspecimen. Locating a permanent code on each test specimencan be accomplished easily by using a code template (Fig. 1).5.2.2.1 Pre-
20、assignment of codes for a definite test period issuggested. After a temporary mark is placed on the specimen,a permanent drilled code (a series of 2.5 mm holes) shouldperforate the test specimen.5.2.3 All test specimens of the same alloy should be cleanedby the same procedure to ensure a comparative
21、 surface finishfollowing the guidance of Practice G1. The recommendedpractice suggested for cleaning is (a) degrease and pickle, ifnecessary, to remove grease, mill scale, or other impurities; (b)scrub with pumice and britle brush until free of water-break;(c) dry with towels; and (d) place in a des
22、iccator for 2 h beforeweighing.5.2.4 Specimens should be weighed (61.0 mg) and originalmass recorded on a data sheet (Table 1). Specific information,such as nominal composition, density, and exposed area shouldalso be recorded.5.2.5 Specimens should be stored in a desiccator or sealed inairtight sto
23、rage bags until the time of exposure.5.3 Exposure of Test Specimens:* Template contains 126 drilled holesFIG. 1 Sample Atmospheric Specimen Drill Code Identification TemplateG92 86 (2010)25.3.1 The frequency at which test specimens should beexposed at a test site is dictated by the specific needs fo
24、r data.5.3.2 Triplicate specimens of each material should be ex-posed for each test period.5.3.3 An exposure period of one year is suggested as aminimum, multiple periods should be considered, for example,3, 6, and 12 months; 1 and 2 years or 1, 2, and 4 years. Shortertest periods may be necessary w
25、here corrosion is severe andlonger test periods where corrosion is less severe.5.3.3.1 Consideration should also be given to use of testperiods which could allow definition of changes in environ-ment corrosivity occurring during an overall longer termevaluation period. For example, exposure of speci
26、mens on theschedule, 03, 36, 69, 912, 06, 612, and 012 months,would allow some assessment of relative changes in corrosivityat a test site during a one year period. While this is a relativelyextensive exposure frequency, it may prove useful in someinstances.5.3.4 A standard atmospheric exposure test
27、 rack (see Prac-tice G50), or other appropriate devices, should be positioned at30 to the horizontal facing south in accordance with PracticeG50. The test specimens should be mounted with porcelaininsulators or other appropriate insulating materials.5.3.5 All test specimens should be positioned at a
28、pproxi-mately the same elevation on the test rack.5.3.6 It is suggested that the general weather conditions bedocumented at the time the specimens are exposed, forexample, clear, cloudy, or rain.35.3.6.1 Initial weather conditions at time of exposure of testspecimens may have an effect on long term
29、corrosion behavior(1).45.4 Removals and Reporting:5.4.1 After the predetermined exposure period is completed(for example, one year), the specimens should be removed andplaced in pre-labeled envelopes. Observations or photographsneeded to document appearance can be made at this time orafter the speci
30、mens reach the laboratory or other process area.Wet specimens should be carefully dried if extended storage(more than 24 h) is anticipated before cleaning.5.4.2 The test specimens being removed should be identi-fied as to exposure location, exposure period, specimen code,original mass, composition,
31、original dimensions, and exposedarea and information documented as shown in Table 1.5.4.3 As each specimen is clearly identified and observa-tions documented, it can be cleaned, in accordance withPractice G1. Specimens should then be dried and placed in adesiccator for2hormore before final weighing.
32、5.4.4 Each specimen should then be weighed to the nearestmilligram and the mass recorded.Also a description of the typeof corrosion attack should be recorded, for example, pitting(depth).5.4.5 After the mass loss has been calculated, a mass lossper unit area (mg/m2) and corrosion rate (mm/y) can bec
33、alculated using the following equations (see Practice G1 forfurther guidance).Ma5MA(1)3Also available are data from the National Climate Data Center, NOAA,Ashville, NC.4The boldface numbers in parentheses refer to a list of references at the end ofthis standard.TABLE 1 Sample Data Sheet for Atmosphe
34、ric Corrosion DataTest Site: Kure Beach (250 m lot) Latitude: 34 008 NExposure Dates: 10/7/61 to 10/6/62 Longitude: 77 558 WMass (g)Material Code Exposure Period(days) Original Final LossMass Loss PerUnit Area(mg/m2)CorrosionRate(mm/y)Cu-steel A1-B2 365 196.583 187.332 9.251 2.86 3 1050.0365Zinc A2-
35、B2 365 67.521 66.938 0.583 1.84 3 1040.0026Test Method DocumentationSteel Zinc1. Composition (weight %) 0.15 C, 1.0 Mn, 0.01 P, 0.027 S, 0.24 Si,0.21 Cu, 0.05 Ni, 0.03 Cr, Balance Fe0.01 Cu, 0.012 Cd, 0.03 Pb, 0.02 Fe,Balance Zn2. Density (g/cm3) 7.85 g/cm37.13 g/cm33. Dimensions (mm) 100 3 150 3 2.
36、00 mm 100 3 150 3 2.00 mm4. Exposed area (cm2) 322.9 cm2317.7 cm2TABLE 2 Sample Data Sheet for Atmospheric Climatological DataTest Site: Kure Beach (250 m lot) Latitude: 34 008 NDates: 5/1/83 to 5/3/83 Longitude: 77 558 WDateTemperature (C) Relative Humidity (%) Precipitation(mm)Time of Wetness(h/da
37、y)High Low Mean High Low Mean Skyward Groundward5/1/83 25.6 12.8 19.2 100 56 82 0 12 135/2/83 26.1 16.7 21.4 97 56 82 0 10 135/3/83 26.7 17.8 22.2 100 60 85 1.3 12 14G92 86 (2010)3where:Ma= mass loss per unit area, milligrams per square metreM = mass loss, milligrams, andA = exposed surface area, me
38、tres squaredC 58.76 3 104!M1a 3 t 3 d(2)where:C = corrosion rate, millimetres per yearM1= mass loss, gramsa = area, centimetres squaredt = time, hoursd = density, grams per cubic centimetre6. Method B6.1 Several atmospheric factors have been identified ashaving a significant influence on the corrosi
39、on of metals anddeterioration of materials. Several of these factors are identi-fied in Table 2 with a suggested format to report these data.6.2 The atmospheric factors to be monitored are dependenton individual needs, and at what frequency the monitoringdevices can be attended. Daily attention is o
40、ften preferred.Available also are computer monitored systems. Suggestionsfor monitoring systems requiring minimal attention are listed inTable 3.6.2.1 Sulfur dioxide can be monitored easily by the use ofsulfation plates (see Practice G91) (2). Monthly attention isneeded to change the plates.6.2.2 Th
41、e hygrothermograph can be used to record tempera-ture and relative humidity. Instruments can be run by eitherbatteries or a hand-wound spring, and will operate for onemonth unattended.6.2.3 The standard 200 mm rain gage needs to be visuallychecked and precipitation (rain, snow) measured after eachoc
42、currence. Also samples of precipitation can be collected forlaboratory analysis (acidity, pH, contaminants).6.2.4 Chloride ion concentration can be monitored by thewet candle method (3). This system may require weeklyattention to replace evaporated distilled water in the 500-mLflask. Also monthly la
43、boratory analysis is required to obtainchloride analyses.6.2.5 Time of wetness (see Practice G84) can be monitoredby the Sereda miniature moisture sensor (4). This device, withsuitable recorder or computer interface, should operate unat-tended on a monthly basis.6.2.6 Other monitoring devices can pr
44、ovide useful climato-logical data to suit special needs (for example, wind speed anddirection, solar radiation, barometric pressure, and dust par-ticles).6.3 Hourly, daily, weekly, and monthly variations in theatmospheric factors are intimately linked with the corrosionprocess. Quantizing these chan
45、ges can provide insight intoobserved corrosion performance. Time averages or other mea-sures of the atmospheric factors over a time span coincidentwith the corrosion experiment can be used.6.4 Atmospheric monitoring should be performed at a siteas near to the placement of the corrosion specimens exp
46、osed inMethod A as possible. Microclimatological variations at agiven test area could reasonably be expected to exist and thusclose proximity of the two methods is important.6.5 Additional information on atmospheric monitoring isavailable in selected references (4-10).7. Keywords7.1 atmospheric char
47、acterization; atmospheric factors; at-mospheric testing; identification; mass loss; monitoring; re-porting; standard test materialsREFERENCES(1) LaQue, F. L., “Corrosion Testing,” Proceedings of ASTM, Vol 51,1951.(2) “The Lead Dioxide Estimate of Sulfur Dioxide Pollution,” Journal ofthe Air Pollutio
48、n Control Association, Vol 18, No. 9, September 1968.(3) Foran, M. R., Gibbons, E. V., and Wellington, J. R., “The Measurementof Atmospheric Sulphur Dioxide and Chlorides,” Chemistry inCanada, Vol 10, No. 5, May 1958, pp. 3341.(4) Sereda, P. J., Cross, S. G., and Slade, H. F., “Measurement ofTime-of
49、-Wetness by Moisture Sensors and Their Calibration,” Atmo-spheric Corrosion of Metals, ASTM STP 767, ASTM, 1982, pp.267285.(5) Bigelow, D. S., NADP Instruction Manual-Site Operation, NationalAtmospheric Deposition Program, Colorado State University, FortCollins, CO, January 1982, p. 30.(6) Bigelow, D. S., NADP Instruction Manual-Site Selection and Instal-lation, National Atmospheric Deposition Program, Colorado StateUniversity, Fort Collins, CO, January 1983, p. 21.(7) Code of Federal Regulations, Title 40-Protection of Environment,Part 50. Office of the Federal Reg
