1、Designation: C871 18Standard Test Methods forChemical Analysis of Thermal Insulation Materials forLeachable Chloride, Fluoride, Silicate, and Sodium Ions1This standard is issued under the fixed designation C871; the number immediately following the designation indicates the year oforiginal adoption
2、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 water-
3、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 equipm
4、entand appropriateness to the concentration of the ion and anypossible ion interferences in the extraction 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 onlya
5、nd are not considered standard.1.4 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, health, and environmental practices and deter-mine the applicability of regu
6、latory limitations prior to use.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade O
7、rganization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C168 Terminology Relating to Thermal InsulationC692 Test Method for Evaluating the Influence of ThermalInsulations on External Stress Corrosion Cracking Ten-dency of Austenitic Stainless SteelC795 Speci
8、fication for Thermal Insulation for Use in Con-tact with Austenitic Stainless SteelC871 Test Methods for Chemical Analysis of Thermal Insu-lation Materials for Leachable Chloride, Fluoride, Silicate,and Sodium IonsD1428 Test Method for Test for Sodium and Potassium InWater and Water-Formed Deposits
9、by Flame Photometry(Withdrawn 1989)32.2 AWWA Standards:4500-Si D Molybdosilicate Method for Silica44500-Si E Heteropoly Blue Method for Silica43. Terminology3.1 DefinitionsRefer to Terminology C168 for definitionsrelating to insulation.4. Summary of Test Methods4.1 Insulation specimens are leached f
10、or 30 min in boilingwater. Tests to determine quantitatively chloride, fluoride,silicate, and 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 longerr
11、ecommended as requested by ASTM International due to useof a specific hazardous substance.4.2.3 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 spectrophotome
12、try test method.4.4.2 Colorimetric test methodsAWWA Methods 4500-SiD and 4500-Si E.4.5 Analysis for Sodium:4.5.1 Flame photometric test method1These test methods are under the jurisdiction of ASTM Committee C16 onThermal Insulation and are the direct responsibility of Subcommittee C16.31 onChemical
13、and Physical Properties.Current edition approved March 1, 2018. Published March 2018. Originallyapproved in 1977. Last previous edition approved in 2011 as C871 111. DOI:10.1520/C0871-18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at servicea
14、stm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4Standard Methods for the Examination of Water and Wastewater, 17th Edition,American Publi
15、c Health Association, Washington, DC, 1989.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decisio
16、n on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1Test Methods D1428.4.5.2 Atomic absorption spectrophotometry test method.4.5.3 Sodium Ion-Selective electrode.5. Significance
17、and Use5.1 Research has demonstrated that in addition to the halideion chloride; fluoride ions, when deposited and concentrated onthe surface of austenitic stainless steel, can contribute toexternal stress corrosion cracking (ESCC) in the absence ofinhibiting ions.5Two widely used insulation specifi
18、cations thatare specific to ESCC allow the use of the same Test MethodsC692 and C871 for evaluation of insulation materials. Bothspecifications require fluoride ions to be included with chlorideions when evaluating the extractable ions.5.2 Chlorides (and fluorides) can be constituents of theinsulati
19、ng 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 stainless steel surface.5.3 The presence of sodium and silicate ions in the insula-tion has been found to inh
20、ibit external stress corrosion crackingcaused by chloride (and fluoride) ions, whether such ions comefrom the insulation itself or from external sources.Furthermore, if the ratio of sodium and silicate ions to chloride(and fluoride) ions is in a certain proportion in the insulation,external stress c
21、orrosion cracking as a result of the presence ofchloride (and fluoride) in the insulation will be prevented or atleast mitigated (see also Specification C795).6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagen
22、ts 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 ascertained that the reagent is of sufficiently highpurity to permit its use without lessening the accuracy of th
23、edetermination.6.2 Purity of WaterDistilled 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. Sampling7.1 With low-chloride insulating materials, wear clean poly-ethylene gloves while taking and handling the
24、 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, drain, and air-dry in aclean, halide-free environment. Store cle
25、an 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 Apparatus and tools used for special preparation andleaching shall be clean and free of chlorides, fluorides,si
26、licates, sodium, and acidic or alkaline materials that mightaffect the chemical test. Distilled water must be used in all testsunless deionized water has been shown to be adequate.8.1.1 For molded insulation, use a band saw or equivalent,making several cuts through the entire cross section of eachpi
27、ece 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 wafersof material be cut between116 and18 in. (1.6 and 3.2 mm)thick.
28、 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 are placed in a suitablecontainer, protected from contamination, and oven dried at 2306 10F (100 6 5C) ( or
29、manufacturers recommendedtemperature) 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 to the nearest 0.1 g.9.1.2 Blender, with jar-top thread preferred.9.1.3 Beaker, 1-L stainless or borosilicate.
30、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 approximately 400 mLof DI or distilledwater for 30 s. While most materials blend to a homogeneousmixture in 30
31、 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 to boiling and maintain at the boiling point for 306 5 min.9.5 Remove from heat, and cool in a cold water bath
32、 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 necessary).9.7 Stir mixture until it is uniform and filter through filterpaper to get a clear filtrate. If n
33、ot 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 by putting this filtrate in the bottle5Whorlow, Kenneth M., Woolridge, Edward and Hutto, Francis B., Jr., “
34、Effectof Halogens and Inhibitors on the External Stress Corrosion Cracking of Type 304Austenitic Stainless Steel”; STP 1320 Insulation Materials: Testing andApplications, Third Volume, Ronald S. Graves and Robert R. Zarr, editors, ASTMWest Conshohocken, PA, 1997, page 485.6Reagent Chemicals, America
35、n 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 States Pharmacopeiaand National Formulary ,
36、U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.C871 182labeled 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 th
37、e weight 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.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.
38、Equivalent results are obtained, and a lengthy filtration step isavoided, by extracting the unpulverized chips.10. Test Procedures10.1 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
39、 theuse of analytical techniques involving known addition (orsample and standard spiking) when the ion concentrations arevery low. It is recommended for chloride ion concentrationsless than 20 ppm.10.1.1 Amperometric-Coulometric Titration Test MethodUse an apparatus7in which direct current between a
40、 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 current betweena pair of indicator electrodes. Because silve
41、r 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 discriminate between chloride,bromide, and iodideall would test
42、 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. Someorganic insulation materials contain carbon-nitrogen com-pounds that are extracted during the
43、water leaching process.These carbon nitrogen ions have the ability to interfere with thesilver nitrate chloride methods causing a higher numericalresult. A chloride-sensitive electrode detects chloride only.10.1.2 Titrimetric Test Method8This method is no longerrecommended as requested by ASTM Inter
44、national due to useof specific hazardous substance.10.1.3 Specific Ion Electrode Test MethodThe chloride-sensitive electrode consists of silver halide/silver sulfide mem-branes bonded into the tip of an epoxy electrode body. Whenthe membrane is in contact with a chloride solution, silver ionsdissolv
45、e 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 potential is measured against a constant referencepotential with a digital pH/mV meter or specific ion mete
46、r.Operation and use follows manufacturers recommendedprocedures, especially noting any corrections for interferencesto determinations. 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, fol
47、lowing the manufacturers directions andappropriate techniques for the concentration of the ion in theextraction solution.10.2 Fluoride 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-sen
48、sitive electrode consists of a single-crystallanthanum fluoride membrane, and an internal reference,bonded into an epoxy body. The crystal is an ionic conductorin which fluoride ions are mobile. When the membrane is incontact with a fluoride solution, an electrode potential developsacross the membra
49、ne. This potential, which depends on thelevel of free fluoride ions in solution, is measured against anexternal constant reference potential with a digital pH/mVmeter or specific ion meter. Operation and use follows manu-facturers recommended procedures, especially noting anycorrections for interferences to determinations.10.2.2 SPADNS Colorimetric Test MethodThis colorimet-ric test method is based on the reaction between fluoride and azirconium-dye lake. The fluoride reacts with the dye lake,dissociating a portion of it into a colorless complex anion(ZrF62) a
