1、Designation: G 92 86 (Reapproved 2003)Standard Practice forCharacterization of Atmospheric Test Sites1This standard is issued under the fixed designation G 92; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revisi
2、on. A number in parentheses indicates the year of last reapproval. A superscriptepsilon (e) 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 characteri-ization can
3、provide 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.
4、The 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 specifiedmater
5、ials and exposure configurations.1.2.2 Method B is specified when atmospheric factors aremonitored on a continuing basis.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-p
6、riate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:A 36/A 36M Specification for Carbon Structural Steel2B6 Specification for Zinc3G1 Practice for Preparing, Cleaning, and Evaluating Cor-rosion Test Speci
7、mens4G50 Practice for Conducting Atmospheric Corrosion Testson Metals4G84 Practice for Measurement of Time-of-Wetness onSurfaces Exposed to Wetting Conditions as inAtmosphericCorrosion Testing4G91 Practice for Monitoring Atmospheric SO2Using theSulfation Plate Technique43. Summary of Methods3.1 Char
8、acterization 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 established by Practice G50.Additional special instructions are identified in this procedurerelating to types of materi
9、als for corrosion characterizationtests, time of test exposure, positioning of test specimens,removal of test specimens and proper identification, cleaningpractices, and reporting of data.3.2 Characterization Method B is to be used when atmo-spheric climatological factors influencing the corrosion o
10、fmetals 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, sulfur dioxide, chlorides,temperature, humidity, precipitation, time of wetness, andatmospheric particulate matter.3.3 Th
11、e 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 continuing basis, bothshould be used at some point in time to establish a data base.The availability of computerized weather
12、 stations greatlyfacilitates the collection of reliable atmospheric data.4. Significance and Use4.1 This practice gives suggested procedures for character-ization of atmospheric test sites. It can be useful to researchers,manufacturers, engineering firms, architects, and constructioncontractors to p
13、rovide 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 of test site.PROCEDURES5. Method A5.1 Materials:1This practice is under the jurisdiction of Committee G01 on Corrosi
14、on ofMetals and is the direct responsibility of Subcommittee G01.04 on AtmosphericCorrosion.Current edition approved Nov. 21, 1986. Published January 1987.2Annual Book of ASTM Standards, Vol 01.04.3Annual Book of ASTM Standards, Vol 02.04.4Annual Book of ASTM Standards, Vol 03.02.1Copyright ASTM Int
15、ernational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.1.1 The materials recommended for conducting atmo-spheric corrosion characterization studies are copper-bearingstructural carbon steel (such as Specification A 36/A 36M with0.2 % copper min) and high-pu
16、rity zinc (Specification B6highgrade).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 supply of the
17、 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 characteriz
18、ation 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-assignmen
19、t 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 surface
20、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 desiccator f
21、or 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 storage bags
22、 until the time of exposure.5.3 Exposure of Test Specimens:5.3.1 The frequency at which test specimens should beexposed at a test site is dictated by the specific needs for 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 i
23、s suggested as aminimum, multiple periods should be considered, for example,* Template contains 126 drilled holesFIG. 1 Sample Atmospheric Specimen Drill Code Identification TemplateG 92 86 (2003)23, 6, and 12 months; 1 and 2 years or 1, 2, and 4 years. Shortertest periods may be necessary where cor
24、rosion 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 specimens on
25、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 rack (s
26、ee 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 approxi-m
27、ately 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.55.3.6.1 Initial weather conditions at time of exposure of testspecimens may have an effect on long term corrosio
28、n behavior(1).5.4 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 specimens reac
29、h 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, original
30、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.5.4.4 Eac
31、h 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 becalculated
32、 using the following equations (see Practice G1forfurther guidance).Ma5MA(1)where:Ma= mass loss per unit area, milligrams per square metreM = mass loss, milligrams, andA = exposed surface area, metres squaredC 58.76 3 104!M1a 3 t 3 d(2)where:C = corrosion rate, millimetres per yearM1= mass loss, gra
33、msa = area, centimetres squaredt = time, hoursd = density, grams per cubic centimetre5Also available are data from the National Climate Data Center, NOAA,Ashville, NC.TABLE 1 Sample Data Sheet for Atmospheric Corrosion DataTest Site: Kure Beach (250m lot)Exposure Dates: 10/7/61 to 10/6/62Latitude:Lo
34、ngitude:34 008 N77 558 WMaterial CodeExposurePeriod (days)Mass (g) Mass Loss PerUnit Area(mg/m2)CorrosionRate(mm/y)Original Final LossCu-steel A1-B2 365 196.583 187.332 9.251 2.86 3 1050.0365Zinc A2-B2 365 67.521 66.938 0.583 1.84 3 1040.0026Test Method DocumentationSteel Zinc1. Composition (weight
35、%) 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 2.00 mm 100 3 150 3 2.00 mm4. Exposed area (cm2) 322.9 cm2317.7 cm2TABLE 2 Sample Data Sheet for Atmosp
36、heric Climatological DataTest Site:Dates:Kure Beach (250m lot)5/1/83 to 5/3/83Latitude:Longitude:34 008 N77 558 WDateTemperature (C) Relative Humidity (%) Precipitation(mm)Time of Wetness(h/day)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
37、 97 56 82 0 10 135/3/83 26.7 17.8 22.2 100 60 85 1.3 12 14G 92 86 (2003)36. Method B6.1 Several atmospheric factors have been identified ashaving a significant influence on the corrosion of metals anddeterioration of materials. Several of these factors are identi-fied in Table 2 with a suggested for
38、mat 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 often preferred.Available also are computer monitored systems. Suggestionsfor monitoring systems requiring minimal at
39、tention 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 The hygrothermograph can be used to record tempera-ture and relative humidity. Instruments can be run by eitherbatte
40、ries 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 eachoccurrence. Also samples of precipitation can be collected forlaboratory analysis (acidity, pH, contaminants).6.2.4
41、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 laboratory analysis is required to obtainchloride analyses.6.2.5 Time of wetness (see Practice G84) can be monitored
42、by 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 provide useful climato-logical data to suit special needs (for example, wind speed anddirection, solar radiation, ba
43、rometric pressure, and dust par-ticles).6.3 Hourly, daily, weekly, and monthly variations in theatmospheric factors are intimately linked with the corrosionprocess. Quantitizing these changes can provide insight intoobserved corrosion performance. Time averages or other mea-sures of the atmospheric
44、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 exposed inMethod A as possible. Microclimatological variations at agiven test area could reasonably be expected to
45、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 characterization; atmospheric factors; at-mospheric testing; identification; mass loss; monitoring; re-porting; stan
46、dard 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 Pollution Control Association, Vol 18, No. 9, September 1968.(3) Foran, M. R., Gibbons, E. V., and Wellington, J. R., “T
47、he 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-Wetness by Moisture Sensors and Their Calibration,” Atmo-spheric Corrosion of Metals, ASTM STP 767, ASTM, 1982,
48、 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, Colora
49、do StateUniversity, Fort Collins, CO, January 1983, p. 21.(7) Code of Federal Regulations, Title 40-Protection of Environment, Part50. Office of the Federal Register, National Archives and RecordsService, General Services Administration, July 1, 1982, pp. 563614.(8) Code of Federal Regulations, Title 40-Protection of Environment, Part58, Office of the Federal Register, National Archives and RecordsService, General Services Administration, July 1, 1982, pp. 144204.(9) Surface Observation, Federal Meteorological Handbook No. 1, 3rdEdition, U.S. Department of Commerce, J
