1、Designation: D 4715 98 (Reapproved 2008)1An American National StandardStandard Test Method forCoking Value of Tar and Pitch (Alcan)1This standard is issued under the fixed designation D 4715; the number immediately following the designation indicates the year oforiginal adoption or, in the case of r
2、evision, 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.1NOTEChanged to SI-only standard editorially in February 2009.1. Scope1.1 This test method covers the determi
3、nation of the cokingvalue of tar and pitch having an ash content not over 0.5 %, asdetermined by Test Method D 2415.1.2 Coking values by this test method are higher than thoseobtained by Test Method D 2416. See the bias statement inSection 13.1.3 The values stated in SI units are to be regarded asst
4、andard. No other units of measurement are included in thisstandard.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 and health practices and determine the ap
5、plica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 850 Test Method for Distillation of Industrial AromaticHydrocarbons and Related MaterialsD 2415 Test Method for Ash in Coal Tar and PitchD 2416 Test Method for Coking Value of Tar and Pitch(Modified Conr
6、adson)D 4296 Practice for Sampling PitchE11 Specification for Wire Cloth and Sieves for TestingPurposes3. Summary of Test Method3.1 A test portion of the tar or pitch is heated for a specifiedtime at 550 6 10C in an electric furnace. The percentage ofresidue is reported as the coking value.4. Signif
7、icance and Use4.1 This test method is useful for indicating the relativecoke-forming propensities and for evaluating and characteriz-ing tars and pitches. The test method can also be used as oneelement in establishing the uniformity of shipments or sourcesof supply.5. Apparatus5.1 Porcelain Crucible
8、, tall form, 30 mL capacity, height of37 mm and diameter 43 mm, with lids of the overlapping type.5.2 Nickel Crucible, 100 to 130 mL capacity, height of 64mm and diameter of 60 mm, with lids.5.3 Wire SupportStainless steel wire support, fitting intothe nickel crucible, used to keep the porcelain cru
9、cible (5.1)inplace within the nickel crucible (5.2). This support shall allowa separation of 10 6 1 mm between the bases of the twocrucibles (see Fig. 1).5.4 Crucible TrayA suitable crucible tray to support thenickel crucibles should be made so that there is at least 7 mmof space between the bottom
10、of the crucible and the base of thefurnace.5.5 Electric Furnace, capable of being controlled at 550 610C.5.6 Sieves1 mm (U.S. Standard No. 18), 300-m (U.S.Standard No. 50) and 212m (U.S. Standard No. 70), con-forming to Specification E11.6. Reagents and Materials6.1 Calcined Petroleum CokeUse the fr
11、action whichpasses a 1-mm mesh sieve (U.S. Standard No. 18) and isretained by a 212m mesh sieve (U.S. Standard No. 70).7. Bulk Sampling7.1 Samples from shipments shall be taken in accordancewith Practice D 4296, and shall be free of foreign substances.Thoroughly mix the sample immediately before rem
12、oving arepresentative portion for the determination or for dehydration.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.05 on Properties of Fuels, Petroleum Coke and Carbon Material.Current editi
13、on approved Dec. 1, 2008. Published February 2009. Originallyapproved in 1987. Last previous edition approved in 2003 as D 471598(2003).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume in
14、formation, 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.8. Dehydration of Sample8.1 Hard PitchIf the solid bulk sample contains freewater, air-dry a representative po
15、rtion.8.2 Soft PitchIf the presence of water is indicated bysurface foam on heating, maintain a representative portion ofthe bulk sample at a temperature between 125 and 150C in anopen container until the surface is free from foam. Take carenot to overheat, and remove heat source immediately whenfoa
16、m subsides.8.3 TarDehydrate a representative portion of the bulksample at atmospheric pressure using a simple side-armdistillation apparatus similar to the one in Test Method D 850and stop the distillation when the temperature reaches 170C.Separate any oil from the water that has distilled over (ifc
17、rystals are present, warm sufficiently to ensure their solution),and thoroughly mix the oil with the residual tar in the still afterthe latter has cooled to a moderate temperature.9. Preparation of Working Specimen9.1 Hard PitchIf the pitch can be crushed at roomtemperature, prepare a 20 6 1 g worki
18、ng specimen by suitablecrushing, mixing, and quartering of a representative portion ofthe dry specimen. The crushing can be performed with a smalljaw crusher and a mortar and pestle. No particle in therepresentative specimen should be larger than 5 mm in anydimension. Crush this specimen so that it
19、will pass a 300 m(U.S. Standard No. 50) mesh sieve. If the ambient temperatureis high, the operation can be facilitated by chilling the samplebeforehand.9.2 Soft Pitch and TarFor soft pitch and tar samples, meltthe sample and take a sufficient amount of the molten mass forthe test. The melting tempe
20、rature must not exceed 150C andthe melting period not longer than 10 min. It is also possible totransfer the required portion of a soft pitch directly to theporcelain crucible, without preliminary treatment.9.3 Preservation of SamplesStore samples as large lumpsor as solidified melts in closed conta
21、iners. Discard workingsamples 24 h after crushing and sieving as changes in compo-sition sometimes occur in pulverized pitch.10. Procedure10.1 For greater accuracy, carry out the determination induplicate.10.2 Heat a clean porcelain crucible with its lid in theelectric furnace, controlled at 550 6 1
22、0C, for 2 h. Aftercooling to ambient temperature in a desiccator, weigh to thenearest 1 mg.10.3 Weigh into the crucible, to the nearest 1 mg, arepresentative portion of 1 6 0.05 g of the test specimen. Placethe wire support in the nickel crucible and make a bed 10 6 1mm thick on the base of the cruc
23、ible with the petroleum coke.Place the porcelain crucible containing the test portion in thewire support so that it sits on the bed of petroleum coke. Coverthe porcelain crucible with its lid and completely fill the spacebetween the two crucibles with the petroleum coke so that theporcelain crucible
24、 is completely embedded. Take care to avoidcontamination of the sample by the coke. Cover the nickelcrucible with its lid.10.4 Place the prepared crucible on the crucible support andplace the whole in the electric furnace controlled at 550 610C, as quickly as possible, in order to avoid heat losses.
25、10.4.1 There should be a space of not less than 7 mmbetween the nickel crucible and the floor, walls, and roof of thefurnace. The space between the crucible and the door, and theback wall of the furnace should not be less than 5 cm.10.5 After 2.5 h, remove the nickel crucible from thefurnace and all
26、ow to cool for 5 to 10 min. Lift the porcelaincrucible out of the coke by means of the wire support, brushand wipe free from adhering coke powder, taking care to avoidcontamination. Place the crucible and contents, covered, in adesiccator and allow to cool to ambient temperature. Weigh tothe nearest
27、 1 mg.NOTE 1To clean the porcelain crucibles and lids, discard the residuesand burn off carbonaceous matter by igniting at 700 to 1000C in anelectric furnace.11. Calculation11.1 Calculate the coking value of the sample as follows:Coking value, mass % 5 100A/B (1)where:A = mass of residue, g, andB =
28、mass of sample, g.11.1.1 If the determination was carried in duplicate, reportthe mean value.12. Report12.1 Report the coking value to the nearest 0.1 mass %.13. Precision and Bias13.1 The following criteria shall be used for judging theacceptability of results (95 % probability).13.1.1 Repeatabilit
29、yDuplicate values by the same opera-tor shall not be considered suspect unless the determinedpercentages differ by more than 1.2 % absolute.13.1.2 ReproducibilityThe values reported by each of twolaboratories, representing the arithmetic average of duplicatedetermination, shall not be considered sus
30、pect unless thereported percentages differ by more than 2.3 % absolute.13.2 BiasCoking values by this test method are about 2percentage points higher than those obtained by Test MethodD 2416.14. Keywords14.1 Alcan; coke-forming; coking value; fixed carbon;pitch; residue; tarFIG. 1 Assembly of Nickel
31、 and Porcelain CruciblesD 4715 98 (2008)12ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and t
32、he riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision
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34、dmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 4715 98 (2008)13
