1、Designation: C 871 04Standard 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 adoptio
2、n or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 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
5、 determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 692 Test Method for Evaluating the Influence of ThermalInsulations on the External Stress Corrosion CrackingTendency of Austenitic SteelC 795 Specification for Thermal Insulation for Use
6、 in Con-tact with Austenitic Stainless SteelD 1428 Test Methods for Sodium and Potassium in Waterand Water-Formed Deposits by Flame Photometry2.2 AWWA Standards:4500-Si D Molybdosilicate Method for Silica34500-Si E Heteropoly Blue Method for Silica33. Summary of Test Methods3.1 Insulation specimens
7、are leached for 30 min in boilingwater. Tests to determine quantitatively chloride, fluoride,silicate, and sodium ions are performed on aliquots of thefiltered leachate solution.3.2 Analysis for Chloride:3.2.1 Amperometric-coulometric titration test method.3.2.2 Titrimetric test method.3.2.3 Specifi
8、c ion electrode test method.3.3 Analysis for Fluoride:3.3.1 Specific ion electrode test method.3.3.2 SPADNS colorimetric test method.3.4 Analysis for Silicate:3.4.1 Atomic absorption spectrophotometry test method.3.4.2 Colorimetric test methodsAWWA Methods 4500-SiD and 4500-Si E.3.5 Analysis for Sod
9、ium:3.5.1 Flame photometric test methodTest Methods D 1428.3.5.2 Atomic absorption spectrophotometry test method.3.5.3 Ross Sodium Ion-Sensitive electrode.44. Significance and Use4.1 It has been demonstrated that chlorides, when depositedand concentrated on the surface of austenitic stainless steel,
10、 cancontribute to external stress corrosion cracking (ESCC).5Analysis for fluoride has been covered because Test MethodsC 871 is the “source document” for other standards that requiretesting for leachable fluoride ions.4.2 Testing6has shown that, using the methodology of TestMethod C 692, neither fl
11、uoride nor iodide nor bromide initiatesESCC in the manner that can be demonstrated with chloride.After being exposed to 1500 mg/kg fluoride for 60 days withno cracking, a change to 1500 mg/kg chloride resulted incracking in 3 days, as required by the metal qualificationprocedure in Test Method C 692
12、. Similar tests with iodide andbromide showed that these ions do not promote ESCC as doeschloride.4.3 Chlorides (and fluorides) can be constituents of theinsulating material or of the environment, or both. Moisture in1These test methods are under the jurisdiction of ASTM Committee C16 onThermal Insu
13、lation and are the direct responsibility of Subcommittee C16.31 onChemical and Physical Properties.Current edition approved Sept. 1, 2004. Published September 2004. Originallyapproved in 1977. Last previous edition approved in 2000 as C 871 95(2000).2For referenced ASTM standards, visit the ASTM web
14、site, 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.3Standard Methods for the Examination of Water and Wastewater, 17th Edition,American Public Health Association,
15、 Washington, DC, 1989.4Available from VWR Scientific, Box 39396, Denver, CO 80239.5Dana, A. W., Jr., “Stress-Corrosion Cracking of Insulated Austenitic StainlessSteel,” ASTM Bulletin No. 225, October 1957, pp. 4652.6Insulation Materials, Testing, and Applications, ASTM STP 1030, ASTM, 1990,pp. 68869
16、8.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.the insulation or from the environment can cause chlorides(and fluorides) to migrate through the insulation and concen-trate at the hot stainless steel surface.4.4 The presence of sod
17、ium 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 silicate ions to chloride (andfluoride) ion
18、s 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).5. Reagents5.1 Purity of ReagentsReagent grade chemicals shall beused in all
19、 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.7Use other grades onlyif is first ascertained that the reagent is of sufficiently
20、highpurity to permit its use without lessening the accuracy of thedetermination.5.2 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.6. Sampling6.1 With low-chloride insulating materi
21、als, 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-tions. Prior to use, rinse gloves twice
22、, drain, and air-dry in aclean, halide-free environment. Store clean gloves in a closedcontainer or envelope.6.2 It is suitable to handle materials with more than 25 ppmchloride with clean, dry hands with no significant contamina-tion.7. Test Specimen7.1 Apparatus and tools used for special preparat
23、ion 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.7.1.1 For molded insulation, use a band saw or equiv
24、alent,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 be included. It is recommended that thin
25、wafersof material be cut between116 and18 in. (1.6 and 3.2 mm)thick. Cut enough material for two 20-g samples.7.1.2 Blanket fibrous materials are cut into strips across theentire width of the blanket using clean, dry scissors.7.1.3 Samples containing moisture are placed in a suitablecontainer, prote
26、cted from contamination, and oven dried at 2306 10F (1006 5C) ( or manufacturers recommended tem-perature) to a constant weight (60.1 g) or overnight.8. Extraction Technique8.1 Apparatus:8.1.1 Electronic Balance, capable of weighing to 2000 gwith readability to the nearest 0.1 g.8.1.2 Blender, Oster
27、izer8with jar-top thread preferred.8.1.3 Beaker, 1-L stainless or Pyrex.8.1.4 Filter, Buchner with suitable filter paper.98.2 Using a closed-top blender, such as a 1-qt Mason jarwith Osterizer blender blades, blend exactly 20.0 g of sample(or other weight if necessary) in approximately 400 mL of DIo
28、r distilled water for 30 s. While most materials blend to ahomogeneous mixture in 30 s, some very hard materialsrequire 60 s or more.8.3 Quantitatively transfer the mixture to a tared 1-L stain-less steel or Pyrex beaker, rinsing with distilled or DI water.8.4 Bring to boiling and maintain at the bo
29、iling point for 306 5 min.8.5 Remove from heat, and cool in a cold water bath toambient temperature.8.6 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 necessary).8.7 Stir mixture un
30、til it is uniform and filter through filterpaper9to 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 Solution A bottle.Complete this filtration by putting this filtrate in
31、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!8.8 Calculate the Gravimetric Conversion Factor (GCF) bydividing the weight of the water by the weight of the sample.In the
32、 ideal case, this is 500/20 = 25. If weights are not exactlyas prescribed, a correct GCF must be calculated and used.8.9 With calsil it has been shown that it is not necessary topulverize the thin chips called for in 7.1.1. Equivalent resultsare obtained, and a lengthy filtration step is avoided, by
33、extracting the unpulverized chips.9. Test Procedures9.1 Chloride DeterminationOne of the following testmethods shall be used on a fresh aliquot from Solution A. The7Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing o
34、f reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.8One such apparatus found acceptable is the 10-speed
35、 Osterizer, manufacturedby the Oster Division, Sunbeam Corporation in Milwaukee, WI 53217. While Ostermanufactures several models, all use the “jar-top thread” on the blade assembly,making it possible to use a 1-qt Mason jar for the pulverization step of theprocedure.9Whatman 41, GF-A, or other filt
36、er paper is suitable for this purpose andcommercially available.C871042precision of the test equipment is often improved through theuse of analytical techniques involving known addtion (orsample and standard spiking) when the ion concentrations arevery low. It is recommended for chloride ion concent
37、rationsless than 20 ppm.9.1.1 Amperometric-Coulometric Titration Test MethodUse an apparatus10in 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 io
38、ns, the appearanceof 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 solu
39、tion can be determined. 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
40、 austenitic stainless steel. Achloride-sensitive electrode detects chloride only.9.1.2 Titrimetric Test Method11Add dilute mercuric ni-trate solution to an acidified aliquot in the presence ofdiphenylcarbazone indicator. At the mercury-chloride equiva-lence point, a blue-violet, mercury-diphenylcarb
41、azone com-plex forms, which is proportional in intensity to the excess ofmercury ion present. The titrimetric procedure is independentof practically all common interferences.9.1.3 Specific Ion Electrode Test MethodThe chloride-sensitive electrode consists of silver halide/silver sulfide mem-branes b
42、onded 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 determined by the sample chloride ion concen
43、-tration. This potential is measured against a constant referencepotential with a digital pH/mV meter or specific ion meter.12Operation and use should follow manufacturers recommendedprocedures, especially noting any corrections for interferencesto determinations. The chloride-sensitive electrode is
44、 notreliable for chloride levels below 2 ppm in Solution A.9.1.4 Ion ChromatographyIt is suitable to use and ionchromatograph, following the manufactures directions andappropriate techniques for the concentration of the ion in theextraction solution.9.2 Fluoride DeterminationOne of the following tes
45、tmethods shall be used on a fresh aliquot from Solution A:9.2.1 Specific Ion Electrode Test Method for FluorideThefluoride-sensitive electrode consists of a single-crystal lantha-num fluoride membrane, and an internal reference, bonded intoan epoxy body. The crystal is an ionic conductor in whichflu
46、oride ions are mobile. When the membrane is in contact witha fluoride solution, an electrode potential develops across themembrane. This potential, which depends on the level of freefluoride ions in solution, is measured against an externalconstant reference potential with a digital pH/mV meter orsp
47、ecific ion meter. Operation and use should follow manufac-turers recommended procedures, especially noting any correc-tions for interferences to determinations.9.2.2 SPADNS Colorimetric Test MethodThis colorimet-ric test method is based on the reaction between fluoride and azirconium-dye lake. The f
48、luoride 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.9.2.3 Ion Chromatography It is suitable to use a
49、nd ionchromatograph, following the manufactures directions andappropriate techniques for the concentration of the ion in theextraction solution.9.3 Silicate DeterminationOne of the following test meth-ods shall be used on a fresh aliquot from Solution A. IfSolution A is cloudy, it shall be refiltered through a 0.45-mmillipore filter or centrifuged until clear before use.9.3.1 Atomic Absorption Spectrophotometry Test MethodAtomize an aliquot from Solution A by means of a nitrousoxide-acetylene flame. The absorption by the silicon atoms ofradiation being emitt
