1、Designation: G 87 02 (Reapproved 2007)Standard Practice forConducting Moist SO2Tests1This standard is issued under the fixed designation G 87; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision. A number in p
2、arentheses indicates the year of last reapproval. A superscriptepsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the apparatus and procedure to beused in conducting qualitative assessment tests in accordancewith the requirements of mater
3、ial or product specifications bymeans of specimen exposure to condensed moisture containingsulfur dioxide.1.2 The exposure conditions may be varied to suit particularrequirements and this practice includes provisions for use ofdifferent concentrations of sulfur dioxide and for tests eitherrunning co
4、ntinuously or in cycles of alternate exposure to thesulfur dioxide containing atmosphere and to the ambientatmosphere.1.3 The variant of the test to be used, the exposure periodrequired, the type of test specimen, and the criteria of failureare not prescribed by this practice. Such details are provi
5、ded inappropriate material and product purchase specifications.1.4 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.5 This standard does not purport to address all of thesafety concerns, if any associated with its use. It is t
6、heresponsibility 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. For a specificwarning statement, see 4.3.2. Referenced Documents2.1 ASTM Standards:2D 714 Test Method for Evaluating Degree of
7、Blistering ofPaintsD 1193 Specification for Reagent WaterD 1654 Test Method for Evaluation of Painted or CoatedSpecimens Subjected to Corrosive EnvironmentsG1 Practice for Preparing, Cleaning, and Evaluating Cor-rosion Test SpecimensG46 Guide for Examination and Evaluation of PittingCorrosion3. Sign
8、ificance and Use3.1 Moist air containing sulfur dioxide quickly produceseasily visible corrosion on many metals in a form resemblingthat occurring in industrial environments. It is therefore a testmedium well suited to detect pores or other sources ofweakness in protective coatings and deficiencies
9、in corrosionresistance associated with unsuitable alloy composition ortreatments.3.2 The results obtained in the test should not be regarded asa general guide to the corrosion resistance of the testedmaterials in all environments where these materials may beused. Performance of different materials i
10、n the test should onlybe taken as a general guide to the relative corrosion resistanceof these materials in moist SO2service.4. Apparatus4.1 The apparatus required for moist SO2testing consists ofa test chamber having an internal capacity of 300 L (10.6 ft3),a supply of sulfur dioxide with metering
11、device, specimensupports, provisions for heating the chamber, and necessarymeans of control. The size and detailed construction of theapparatus are optional, provided the conditions obtained meetthe requirements of this practice. Suitable apparatus which maybe used to obtain these conditions is desc
12、ribed inAppendix X1.4.2 Drops of condensing moisture which accumulate on theceiling of the chamber shall not be permitted to fall on thespecimens being tested.1This practice is under the jurisdiction of ASTM Committee G01 on Corrosionof Metals and is the direct responsibility of Subcommittee G01.05
13、on LaboratoryCorrosion Tests.Current edition approved May 1, 2007. Published May 2007. Originallyapproved in 1997. Last previous edition approved in 2002 as G 87-02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Bo
14、ok of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.3 (WarningSuck-back into cylinder may cause explo-sion. Always use a check valv
15、e, vacuum break, or otherprotective apparatus in any line or piping from cylinder to testchamber to prevent suck-back. Installation of the chamberunder a fume hood is recommended.)5. Reagents5.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is in
16、tended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.3Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use wi
17、thout lessening theaccuracy of the determination.5.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedby Type IV of Specification D 1193.5.3 A commercially available source of bottled SO2gashaving a minimum purity of 99.9 % (liquid pha
18、se) with properregulator, and means of measuring the volumes of gas requiredfor delivery into test chamber shall be provided.5.4 The volume of gas delivered into test chamber shall bemeasured by means of either a properly calibrated flowmeter(rotameter type) with metering valve, or in a gas buret us
19、ingviscous 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 indelivery tubes between flowmeter or gas burette and testchamber.6. Sampling6.1 The specific location of samples in a mill p
20、roduct, thenumber of samples that should be tested, and other factorsconcerning sampling, are not within the scope of this practice.These factors should be mutually agreed upon between pur-chaser and supplier (see 7.1).7. Test Specimens7.1 Select the number and type of test specimens, and theirshape
21、 and dimensions according to the specification coveringthe product or material being tested or agreed upon betweenpurchaser and supplier.7.2 The total combined exposed surface area of the materialtested at any one time should be substantially the same andunless otherwise agreed upon, it shall be 0.5
22、 6 0.1 m2(5.4 ft26 1ft2).7.2.1 More specimens of the same material may be added, ifneeded.7.3 To obtain quantitative corrosion-rate data, only materi-als 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 (se
23、e Prac-tice G1). Unless otherwise agreed upon the cleaning methodshall be optional depending on the nature of the surface and ofthe likelihood of contamination. The cleaning method shall notinclude the use of abrasives (other than a paste of puremagnesium oxide), corrosive solvents, corrosion-promot
24、ingmaterials or protective film formers. Care in handling isnecessary 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 isminimized in the area adjacent to the cut. Unless otherwisespecif
25、ied, adequately protect the cut edges by coating themwith a suitable medium, stable under the conditions of the test,such as wax or tape. High-quality platers tape or microcrystal-line wax are generally suitable.7.5 Position of Specimens During Test:7.5.1 Place the test specimens in the cabinet so t
26、hat no partof any specimen is within 20 mm (0.78 in.) of another or within100 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 maycondense on any of them or their supports will n
27、ot fall on otherspecimens placed at lower levels. If possible place all testspecimens on the same horizontal plane so they are exposed toequal concentrations of SO2gas.7.5.3 Unless otherwise agreed upon, the angle of inclinationof test surfaces to the vertical is optional. A near verticalorientation
28、 (0 to 10 from vertical) is suggested unless other-wise agreed upon or specified.8. Conditioning8.1 Operate a new chamber for at least ten 24-h cycleswithout introduction of any test material by the procedureapplicable to an atmosphere containing an addition of 2 L (122in.3) of sulfur dioxide before
29、 it is brought into use for testing.This should reduce any risks of contamination of the atmo-sphere by vapors from construction materials of chamber.9. Procedure9.1 Introduce 2 6 0.2 L (122 in.36 12 in.3) of distilledwater into the base of chamber.9.2 Place the test specimens in the chamber and clo
30、se thedoor/lid.9.3 Introduce the volume of sulfur dioxide, required by thegoverning materials specification, into the chamber through theinlet pipe. Usually this volume will be 0.2, 1, or 2 L (12 in.3,61 in.3, or 122 in.36 12 in.3).9.4 Switch on the heater and raise the temperature inside thechamber
31、 to 40 6 3C (104 6 5.4F) in about 1.5 h. Make surethe heating is under control to keep the temperature inside thechamber at 40 6 3C (104 6 5.4F) for the specified period.Each set point and its tolerance represents an operationalcontrol point for equilibrium conditions at a single location inthe cabi
32、net which may not necessarily represent the uniformityof conditions throughout the cabinet.9.5 One test cycle is 24 h. Either Method A or B, and thenumber of cycles shall be designated by the specification forthe material or product being tested or mutually agreed upon bythe purchaser and seller. Fo
33、r either method, replace the water in3Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for Laboratory U.K. Chemicals, BDH Ltd., Poole, Do
34、rset, and the United States Pharmacopeia andNational Formulary, U.S. Pharamacopeial Convention, Inc. (USPC) Rockville,MD.”G 87 02 (2007)2the chamber and the sulfur dioxide in the air of the chamberbefore each 24 h cycle begins.9.5.1 Method A, Continuous ExposureThe specimensshall remain continuously
35、 exposed to the atmosphere in thechamber for 24 h. Replacement of the water and sulfur dioxidefor a second period of test shall be made with a minimum ofdisturbance of the test specimens.9.5.2 Method B, Alternating Exposure Expose the speci-mens for 8 h, followed by drying in the ambient conditionsi
36、nside the chamber for 16 h. Ambient conditions shall be anindoor atmosphere with no unusual pollution other than thatarising from the test chamber. Such conditions shall becontrolled to a temperature in the range of 20 to 30C (68 to86F), and a relative humidity below 75 %.9.6 Duration of TestThe num
37、ber of cycles shall be des-ignated by the specification for the material or product beingtested or mutually agreed upon by purchaser and seller.9.7 Cleaning of Tested SpecimensAt the end of the testperiod, remove the specimens from the chamber. Before theyare examined, allow them to hang freely in a
38、 normal indooratmosphere until any fluid corrosion product dries. Examinewith all corrosion product in position and any cleaning carriedout depends on the criteria laid down for evaluation of the testresult (see Practice G1).10. Evaluation of Results10.1 Different criteria for evaluation of the resu
39、lts of the testmay be applied to meet particular requirements, for example,mass change, change in appearance, alteration revealed bymicrographic examination, or change in mechanical properties.Usually the appropriate criteria will be indicated in thespecification for the material or product tested.
40、For mostroutine applications of the test, only the following need to beconsidered:10.1.1 Appearance after drying in air,10.1.2 Appearance after removing superficial corrosionproducts by washing with water and a soft bristle brush,10.1.3 The number and distribution of corrosion defects, forexample, p
41、its, cracks, blisters, and other defects may conve-niently be assessed by methods such as that described in TestMethod D 1654, Test Method D 714, and Guide G46.10.1.4 The number of cycles elapsing before the appearanceof the first sign of corrosion.11. Report11.1 The report shall indicate the outcom
42、e of the testaccording to the criteria for evaluation of results prescribed forthe test. The result obtained for each specimen tested and,when appropriate, the average result for a group of replicatetest specimens shall be reported. The report, may, if required,be accompanied by photographic records
43、 of the tested speci-mens.11.2 The report shall contain information about all testdetails. This information may vary according to the purposes ofthe test and to the directions prescribed for it but a general listof the details likely to be required is as follows:11.2.1 Chemical composition of the ma
44、terial tested,11.2.2 Dimensions and shape of the test specimen and thenature and area of the surface tested,11.2.3 Preparation of the test specimen including any clean-ing treatment applied and any protection given to edges orother special areas. Known characteristics of any coating withan indicatio
45、n of the surface finish,11.2.4 Amount of sulfur dioxide introduced per cycle,11.2.5 Number of test specimens subjected to test represent-ing each material or product,11.2.6 Method used to clean test specimens after the test andan indication of the loss of mass resulting from the cleaningoperation, w
46、hen appropriate,11.2.7 Temperature of test,11.2.8 Duration of test (number of cycles), and11.2.9 Character of any control test panels placed in thecabinet expressly to check the correctness of the operatingconditions and the results obtained with them.11.2.10 Method A or B.APPENDIXES(Nonmandatory In
47、formation)X1. MOIST SO2TEST APPARATUSX1.1 LocationX1.1.1 The chamber shall be located in an area free ofunusual pollution, direct sunlight, and drafts. Temperatureshould be controlled between 20 to 30C (68 to 86F) at arelative humidity below 75 %.X1.2 ChamberX1.2.1 Standard SO2chambers are available
48、 from severalsuppliers, but certain pertinent details are required before theywill function according to this practice and provide consistentcontrol for duplication of results.X1.2.2 The chamber consists of the basic chamber, inert,non-conducting specimen supports, provisions for heating thechamber,
49、 and suitable controls for maintaining and indicatingthe desired temperature and relative humidity.X1.2.3 The chamber shall have an inlet tube through whichgas can be introduced into the chamber located at a point noless than 50 mm (1.95 in.) above the internal floor, a means byG 87 02 (2007)3which excess pressure can be relieved located in or near theceiling and a suitable drain in the floor of the chamber.X1.2.4 The floor and lower parts of the walls of chambershall be capable of being heated from an external source andmust be able to retain without leakage at least
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