1、Designation: G92 86 (Reapproved 2015)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、.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon () 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 provide
3、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 meth
4、ods 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 MethodAis to be used when atmospheric corrosion ismonitored on a continuing basis at a test site using specifiedmaterials and e
5、xposure 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 thesafety co
6、ncerns, 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 Carbon Str
7、uctural 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 AtmosphericCorrosion Tes
8、tingG91 Practice for Monitoring Atmospheric SO2DepositionRate for Atmospheric Corrosivity Evaluation3. 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
9、procedure established 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 r
10、eporting of data.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 limi
11、ted to, sulfur 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
12、on a continuing 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 atmos
13、pheric test sites. 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 forclassify
14、ing the type 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 Nov. 1, 2015. Published December 2015. Last previousedition approved in 2010 as G928
15、6(2010). DOI: 10.1520/G0092-86R15.2For 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.Copyright ASTM Internationa
16、l, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1PROCEDURES5. 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 %
17、 copper min) and 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 t
18、hatan ample supply 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 fo
19、r the planned characterization test.5.2 Material Preparation:5.2.1 Test specimens should be sheared to size, for example,100 150 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
20、).5.2.2.1 Pre-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
21、 a comparative 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)
22、place in a desiccator 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
23、inairtight storage 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 (2015)25.3.1 The frequency at which test specimens should beexposed at a test site is dictated by the spe
24、cific 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 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
25、be necessary where 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, exp
26、osure of specimens 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
27、 exposure test 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 p
28、ositioned at approxi-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
29、 on long term 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 ora
30、fter the specimens 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,
31、 composition, 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 f
32、inal weighing.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
33、(mm/y) can becalculated using the following equations (see Practice G1 forfurther guidance).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 At
34、mospheric Corrosion DataTest Site: Kure Beach (250 m lot) Latitude: 34 00 NExposure Dates: 10/7/61 to 10/6/62 Longitude: 77 55 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 1050.0365Zinc A
35、2-B2 365 67.521 66.938 0.583 1.84 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) 100 150 2.00 m
36、m 100 150 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 00 NDates: 5/1/83 to 5/3/83 Longitude: 77 55 WDateTemperature (C) Relative Humidity (%)Precipitation(mm)Time of Wetness(h/day)High Low
37、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 (2015)3Ma5MA(1)where:Ma= mass loss per unit area, milligrams per square metreM = mass loss, milligrams, andA = exposed surface area, metre
38、s squaredC 58.76 3104!M1a 3t 3d(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 corrosion of
39、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 often p
40、referred.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 The hygr
41、othermograph 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 eachoccurren
42、ce. 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 laborato
43、ry 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 provide
44、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 changes ca
45、n 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 exposed i
46、nMethod 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 characteri
47、zation; atmospheric factors; at-mospheric testing; identification; mass loss; monitoring; re-porting; standard test materialsTABLE 3 Recommended Methods for Monitoring AtmosphericFactorsAtmospheric Factors Monitoring DeviceSulfur dioxide sulfation plateChloride ion wet candleTemperature/humidity hyg
48、rothermograph (combination of hygrographand thermograph used for recordingtemperature and humidity)Precipitation standard 200 mm rain/snow gage (periodicsampling for pH range)Time of wetness Cu/Au sensor (procedure defined inPractice G84)Climatological data National Weather ServiceAANational Weather
49、 Service monitors climatological data in many areas and dataare available from the National Climate Data Center, NOAA, Ashville, NC.G92 86 (2015)4REFERENCES(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., “The Measure-ment of Atmospheric Sulphur Dioxide and Chlorides,” Chemistry inCanada, Vol 10, No. 5, May 1958, pp. 3341.(4) Sered
