1、Designation: C 871 08aStandard Test Methods forChemical Analysis of Thermal Insulation Materials forLeachable Chloride, Fluoride, Silicate, and Sodium Ions1This standard is issued under the fixed designation C 871; the number immediately following the designation indicates the year oforiginal adopti
2、on or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover laboratory procedures for thedetermination of wat
3、er-leachable chloride, fluoride, silicate,and sodium ions in thermal insulation materials in the parts permillion range.1.2 Selection of one of the test methods listed for each of theionic determinations required shall be made on the basis oflaboratory capability and availability of the required equ
4、ipmentand appropriateness to the concentration of the ion in theextraction solution.1.3 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1
5、.4 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-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Do
6、cuments2.1 ASTM Standards:2C 168 Terminology Relating to Thermal InsulationC 692 Test Method for Evaluating the Influence of ThermalInsulations on External Stress Corrosion Cracking Ten-dency of Austenitic Stainless SteelC 795 Specification for Thermal Insulation for Use in Con-tact with Austenitic
7、Stainless SteelC 871 Test Methods for Chemical Analysis of ThermalInsulation Materials for Leachable Chloride, Fluoride,Silicate, and Sodium IonsD 1428 Test Method for Sodium and Potassium in Waterand Water-Formed Deposits by Flame Photometry32.2 AWWA Standards:4500-Si D Molybdosilicate Method for S
8、ilica44500-Si E Heteropoly Blue Method for Silica43. Terminology3.1 DefinitionsRefer to Terminology C 168 for definitionsrelating to insulation.4. Summary of Test Methods4.1 Insulation specimens are leached for 30 min in boilingwater. Tests to determine quantitatively chloride, fluoride,silicate, an
9、d sodium ions are performed on aliquots of thefiltered leachate solution.4.2 Analysis for Chloride:4.2.1 Amperometric-coulometric titration test method.4.2.2 Titrimetric test method. This method is no longerrecommended as requested by ASTM International due to useof a specific hazardous substance.4.
10、2.3 Specific ion electrode test method.4.3 Analysis for Fluoride:4.3.1 Specific ion electrode test method.4.3.2 SPADNS colorimetric test method.4.4 Analysis for Silicate:4.4.1 Atomic absorption spectrophotometry test method.4.4.2 Colorimetric test methodsAWWA Methods 4500-SiD and 4500-Si E.4.5 Analy
11、sis for Sodium:4.5.1 Flame photometric test methodTest Methods D 1428.4.5.2 Atomic absorption spectrophotometry test method.4.5.3 Sodium Ion-Selective electrode.5. Significance and Use5.1 Research has demonstrated that in addition to the halideion chloride; fluoride ions, when deposited and concentr
12、ated onthe surface of austenitic stainless steel, can contribute to1These test methods are under the jurisdiction of ASTM Committee C16 onThermal Insulation and are the direct responsibility of Subcommittee C16.31 onChemical and Physical Properties.Current edition approved Dec. 1, 2008. Published Ja
13、nuary 2009. Originallyapproved in 1977. Last previous edition approved in 2008 as C 871 08.2For 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 Su
14、mmary page onthe ASTM website.3Withdrawn.4Standard Methods for the Examination of Water and Wastewater , 17th Edition,American Public Health Association, Washington, DC, 1989.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.external s
15、tress corrosion cracking (ESCC) in the absence ofinhibiting ions.5Two widely used insulation specifications thatare specific to ESCC allow the use of the same Test MethodsC 692 and C 871 for evaluation of insulation materials. Bothspecifications require fluoride ions to be included with chlorideions
16、 when evaluating the extractable ions.5.2 Chlorides (and fluorides) can be constituents of theinsulating material or of the environment, or both. Moisture inthe insulation or from the environment can cause chlorides(and fluorides) to migrate through the insulation and concen-trate at the hot stainle
17、ss steel surface.5.3 The presence of sodium and silicate ions in the insula-tion has been found to inhibit external stress corrosion crackingcaused by chloride (and fluoride) ions, whether such ions comefrom the insulation itself or from external sources. Further-more, if the ratio of sodium and sil
18、icate ions to chloride (andfluoride) ions is in a certain proportion in the insulation,external stress corrosion cracking as a result of the presence ofchloride (and fluoride) in the insulation will be prevented or atleast mitigated (see also Specification C 795).6. Reagents6.1 Purity of ReagentsRea
19、gent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.6Use other grades onlyif is first ascertai
20、ned that the reagent is of sufficiently highpurity to permit its use without lessening the accuracy of thedetermination.6.2 Purity of Water Distilled or deionized water (DI),having maximum conductivity of 2.5 S/cm and containingless than 0.1 ppm of chloride ions shall be used in all tests.7. Samplin
21、g7.1 With low-chloride insulating materials, wear clean poly-ethylene gloves while taking and handling the sample to avoidchloride contamination from perspiration. Do not use glovesmade from chloride-containing compounds such as neopreneor saran, or materials with metallic chlorides in their formula
22、-tions. Prior to use, rinse gloves twice, drain, and air-dry in aclean, halide-free environment. Store clean gloves in a closedcontainer or envelope.7.2 It is suitable to handle materials with more than 25 ppmchloride with clean, dry hands with no significant contamina-tion.8. Test Specimen8.1 Appar
23、atus and tools used for special preparation andleaching shall be clean and free of chlorides, fluorides, sili-cates, sodium, and acidic or alkaline materials that might affectthe chemical test. Distilled water must be used in all testsunless deionized water has been shown to be adequate.8.1.1 For mo
24、lded insulation, use a band saw or equivalent,making several cuts through the entire cross section of eachpiece of insulation to be tested. Each specimen shall berepresentative of the entire cross section of the piece, exceptthat metal screen, or expanded metal used as a supportivefacing shall not b
25、e included. It is recommended that thin wafersof material be cut between116 and18 in. (1.6 and 3.2 mm)thick. Cut enough material for two 20-g samples.8.1.2 Blanket fibrous materials are cut into strips across theentire width of the blanket using clean, dry scissors.8.1.3 Samples containing moisture
26、are placed in a suitablecontainer, protected from contamination, and oven dried at 2306 10F (1006 5C) ( or manufacturers recommended tem-perature) to a constant weight (60.1 g) or overnight.9. Extraction Technique9.1 Apparatus:9.1.1 Electronic Balance, capable of weighing to 2000 gwith readability t
27、o the nearest 0.1 g.9.1.2 Blender, with jar-top thread preferred.9.1.3 Beaker, 1-L stainless or borosilicate.9.1.4 Filter, Buchner with suitable filter paper.9.2 Using a closed-top blender, such as a 1-qt Mason jarwith blender blades, blend exactly 20.0 g of sample (or otherweight if necessary) in a
28、pproximately 400 mLof DI or distilledwater for 30 s. While most materials blend to a homogeneousmixture in 30 s, some very hard materials require 60 s or more.9.3 Quantitatively transfer the mixture to a tared 1-L stain-less steel or borosilicate beaker, rinsing with distilled or DIwater.9.4 Bring t
29、o boiling and maintain at the boiling point for 306 5 min.9.5 Remove from heat, and cool in a cold water bath toambient temperature.9.6 Remove water from the outside of the beaker and placeon a balance. Add DI (or distilled) water to bring amount ofwater up to exactly 500.0 mL(g) (or other weight if
30、 necessary).9.7 Stir mixture until it is uniform and filter through filterpaper to get a clear filtrate. If not clear after the first filtration,refilter through a finer filter paper. The first small portion offiltrate is used to rinse the receiving flask and SolutionAbottle.Complete this filtration
31、 by putting this filtrate in the bottlelabeled Solution A. Since the relationship between solids andliquid has been established, it is not necessary to filter all of theextract. DO NOT WASH THE FILTER CAKE!9.8 Calculate the Gravimetric Conversion Factor (GCF) bydividing the weight of the water by th
32、e weight of the sample.In the ideal case, this is 500/20 = 25. If weights are not exactlyas prescribed, a correct GCF must be calculated and used.9.9 With calcium silicate insulation it has been shown that itis not necessary to pulverize the thin chips called for in 8.1.1.5Whorlow, Kenneth M., Woolr
33、idge, Edward and Hutto, Francis B., Jr., “Effect ofHalogens and Inhibitors on the External Stress Corrosion Cracking of Type 304Austenitic Stainless Steel”; STP 1320 Insulation Materials: Testing and Applica-tions, Third Volume, Ronald S. Graves and Robert R. Zarr, editors , ASTM WestConshohocken, P
34、A, 1997 page 4856Reagent 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 LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United
35、States Pharmacopeiaand National Formulary , U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.C 871 08a2Equivalent results are obtained, and a lengthy filtration step isavoided, by extracting the unpulverized chips.10. Test Procedures10.1 Chloride DeterminationOne of the following testmethod
36、s shall be used on a fresh aliquot from Solution A. Theprecision of the test equipment is often improved through theuse of analytical techniques involving known addition (orsample and standard spiking) when the ion concentrations arevery low. It is recommended for chloride ion concentrationsless tha
37、n 20 ppm.10.1.1 Amperometric-Coulometric Titration Test MethodUse an apparatus7in which direct current between a pair ofsilver electrodes causes electrochemical oxidation of the anodeand produces silver ions at a constant rate. When all of thechloride ions have combined with silver ions, the appeara
38、nceof free silver ions causes an abrupt increase in current betweena pair of indicator electrodes. Because silver ions are generatedat a constant rate, the amount used to precipitate the chlorideions is proportional to the elapsed time. Hence, the chloridecontent of the titration solution can be det
39、ermined. Since thecoulometric titrator would not discriminate between chloride,bromide, and iodideall would test as chloridein somecases it is practical to differentiate between the halides to showchloride only, since the others have not been shown to causestress corrosion cracking in austenitic sta
40、inless steel. Achloride-sensitive electrode detects chloride only.10.1.2 Titrimetric Test Method8This method is no longerrecommended as requested by ASTM International due to useof specific hazardous substance.10.1.3 Specific Ion Electrode Test MethodThe chloride-sensitive electrode consists of silv
41、er halide/silver sulfide mem-branes bonded into the tip of an epoxy electrode body. Whenthe membrane is in contact with a chloride solution, silver ionsdissolve from the membrane surface and the electrode developsa potential due to the silver ion concentration. This concentra-tion is in turn determi
42、ned by the sample chloride ion concen-tration. This potential is measured against a constant referencepotential with a digital pH/mV meter or specific ion meter.Operation and use should follow manufacturers recommendedprocedures, especially noting any corrections for interferencesto determinations.
43、The chloride-sensitive electrode is notreliable for chloride levels below 2 ppm in Solution A.10.1.4 Ion ChromatographyIt is suitable to use an ionchromatograph, following the manufacturers directions andappropriate techniques for the concentration of the ion in theextraction solution.10.2 Fluoride
44、DeterminationOne of the following testmethods shall be used on a fresh aliquot from Solution A:10.2.1 Specific Ion Electrode Test Method for FluorideThe fluoride-sensitive electrode consists of a single-crystallanthanum fluoride membrane, and an internal reference,bonded into an epoxy body. The crys
45、tal is an ionic conductorin which fluoride ions are mobile. When the membrane is incontact with a fluoride solution, an electrode potential developsacross the membrane. This potential, which depends on thelevel of free fluoride ions in solution, is measured against anexternal constant reference pote
46、ntial with a digital pH/mVmeter or specific ion meter. Operation and use should followmanufacturers recommended procedures, especially notingany corrections for interferences to determinations.10.2.2 SPADNS Colorimetric Test MethodThis colorimet-ric test method is based on the reaction between fluor
47、ide and azirconium-dye lake. The fluoride reacts with the dye lake,dissociating a portion of it into a colorless complex anion (ZrF62) and the dye. As the amount of fluoride is increased, thecolor produced becomes progressively lighter or different inhue, depending on the reagent used.10.2.3 Ion Chr
48、omatography It is suitable to use and ionchromatograph, following the manufactures directions andappropriate techniques for the concentration of the ion in theextraction solution.10.3 Silicate DeterminationOne of the following testmethods shall be used on a fresh aliquot from Solution A. IfSolution
49、A is cloudy, it shall be refiltered through a 0.45-mmillipore filter or centrifuged until clear before use.10.3.1 Atomic Absorption Spectrophotometry TestMethodAtomize an aliquot from Solution A by means of anitrous oxide-acetylene flame. The absorption by the siliconatoms of radiation being emitted by a silicon hollow cathodelamp source provides a measure of the amount of siliconpresent in the solution, using an atomic absorption spectropho-tometer.10.3.2 Colorimetric Test MethodThis test method coversthe determination of soluble silica (SiO2) by the moly
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