1、Designation: C 871 08Standard 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 External Stress Corrosion Cracking Ten-dency of Austenitic Stainless SteelC 795 Specification for Thermal Insulation
6、 for Use in Con-tact with Austenitic Stainless SteelD 1428 Test Method for Sodium and Potassium in Waterand Water-Formed Deposits by Flame Photometry32.2 AWWA Standards:4500-Si D Molybdosilicate Method for Silica44500-Si E Heteropoly Blue Method for Silica43. Summary of Test Methods3.1 Insulation sp
7、ecimens 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. This
8、 method is no longerrecommended as requested by ASTM International due to useof a specific hazardous substance.3.2.3 Specific 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 abso
9、rption spectrophotometry test method.3.4.2 Colorimetric test methodsAWWA Methods 4500-SiD and 4500-Si E.3.5 Analysis for Sodium:3.5.1 Flame photometric test methodTest Methods D 1428.3.5.2 Atomic absorption spectrophotometry test method.3.5.3 Sodium Ion-Selective electrode.4. Significance and Use4.1
10、 It has been demonstrated that chlorides, when depositedand concentrated on the surface of austenitic stainless steel, 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 requir
11、etesting for leachable fluoride ions.4.2 Testing6has shown that, using the methodology of TestMethod C 692, neither fluoride 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 1
12、500 mg/kg chloride resulted incracking in 3 days, as required by the metal qualificationprocedure in Test Method C 692. Similar tests with iodide andbromide showed that these ions do not promote ESCC as doeschloride.1These test methods are under the jurisdiction of ASTM Committee C16 onThermal Insul
13、ation and are the direct responsibility of Subcommittee C16.31 onChemical and Physical Properties.Current edition approved March 1, 2008. Published April 2008. Originallyapproved in 1977. Last previous edition approved in 2004 as C 871 04.2For referenced ASTM standards, visit the ASTM website, www.a
14、stm.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.3Withdrawn.4Standard Methods for the Examination of Water and Wastewater, 17th Edition,American Public Health Association,
15、 Washington, DC, 1989.5Dana, 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. 688698.1Copyright ASTM International, 100 Barr Harbor Drive, PO Bo
16、x C700, West Conshohocken, PA 19428-2959, United States.4.3 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
17、at the hot stainless steel surface.4.4 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
18、 of sodium and silicate 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).5. Reagents5.1 Pur
19、ity of ReagentsReagent 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.7Use other grades onlyif
20、 is first ascertained that the reagent is of sufficiently 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 al
21、l tests.6. Sampling6.1 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 chloride
22、s in their formula-tions. Prior to use, rinse gloves twice, 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
23、 Specimen7.1 Apparatus 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 ade
24、quate.7.1.1 For molded 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 supportive
25、facing shall not be 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.7.1.2 Blanket fibrous materials are cut into strips across theentire width of the blanket using clean, dry scissors.7.1.3 Samples co
26、ntaining moisture 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.8. Extraction Technique8.1 Apparatus:8.1.1 Electronic Balance, capable of weighing to 2000 g
27、with readability to the nearest 0.1 g.8.1.2 Blender, with jar-top thread preferred.8.1.3 Beaker, 1-L stainless or borosilicate.8.1.4 Filter, Buchner with suitable filter paper.8.2 Using a closed-top blender, such as a 1-qt Mason jarwith blender blades, blend exactly 20.0 g of sample (or otherweight
28、if necessary) in approximately 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.8.3 Quantitatively transfer the mixture to a tared 1-L stain-less steel or borosilicate beaker, rinsing with distilled or D
29、Iwater.8.4 Bring to boiling and maintain at the boiling 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) (
30、or other weight if necessary).8.7 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.Comple
31、te this filtration 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!8.8 Calculate the Gravimetric Conversion Factor (GCF) bydividing the weight
32、of the water by the 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.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 obtaine
33、d, and a lengthy filtration step is avoided, byextracting the unpulverized chips.9. Test Procedures9.1 Chloride DeterminationOne of the following testmethods shall be used on a fresh aliquot from Solution A. Theprecision of the test equipment is often improved through theuse of analytical techniques
34、 involving known addition (orsample and standard spiking) when the ion concentrations arevery low. It is recommended for chloride ion concentrationsless than 20 ppm.7Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society, Washington, DC. For suggestions on the testing
35、 of 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.C8710829.1.1 Amperometric-Coulometric Titration Te
36、st MethodUse an apparatus8in 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 appearanceof free silver ions causes an abrupt increase in c
37、urrent 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 determined. Since thecoulometric titrator would not disc
38、riminate 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 stainless steel. Achloride-sensitive electrode detects c
39、hloride only.9.1.2 Titrimetric Test Method9This method is no longerrecommended as requested by ASTM International due to useof specific hazardous substance.9.1.3 Specific Ion Electrode Test MethodThe chloride-sensitive electrode consists of silver halide/silver sulfide mem-branes bonded into the tip
40、 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-tration. This pot
41、ential 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. The chloride-sensitive electrode is notreliable for chl
42、oride levels below 2 ppm in Solution A.9.1.4 Ion ChromatographyIt is suitable to use an ionchromatograph, following the manufacturers directions andappropriate techniques for the concentration of the ion in theextraction solution.9.2 Fluoride DeterminationOne of the following testmethods shall be us
43、ed 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 whichfluoride ions are mobil
44、e. 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 orspecific ion meter. Op
45、eration 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 fluoride reacts with
46、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 and ionchromatograph,
47、 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-mmi
48、llipore 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 emitted by a silicon hollow cathode lampsource provides a mea
49、sure of the amount of silicon present inthe solution, using an atomic absorption spectrophotometer.9.3.2 Colorimetric Test MethodThis test method coversthe determination of soluble silica (SiO2) by the molybdosili-cate colorimetric procedure. In this test method, ammoniummolybdate at low pH reacts with soluble silicate or phosphateto produce heteropoly acids. Oxalic acid is used to destroy themolybdophosphoric acid but not the molybdosilicic acid. Theintensity of the yellow molybdosilicate complex follows Beerslaw. This test method is an adaption of AWWAMet
