ASTM_C_783_-_85_2015.pdf

Designation:C78385(Reapproved 2015)An American National StandardStandard Practice forCore Sampling of Graphite Electrodes1This standard is issued under the fixed designation C783;the number immediately following the designation indicates the year oforiginal adoption 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 This practice was developed for electric-arc furnacegraphite electrodes,and covers a procedure and equipment forobtaining core samples from electrodes in a manner that doesnot destroy the electrode nor prevent its subsequent use asoriginally intended.However,the minimum electrodediameter,for which extraction of a core sample using thispractice does not influence subsequent use,is influenced by theparticular application and must be determined by the user.Graphite electrodes for use in electric arc furnaces are usuallysolid cylinders of graphite with threaded sockets machined ineach end.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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 determine the applica-bility of regulatory limitations prior to use.NOTE1The followingASTM standards are noted as sources of usefulinformation:Test Methods C559,C611,C651,C747,C1025,and C1039.2.Referenced Documents2.1 ASTM Standards:2C559 Test Method for Bulk Density by Physical Measure-ments of Manufactured Carbon and Graphite ArticlesC611 Test Method for Electrical Resistivity of ManufacturedCarbon and Graphite Articles at Room TemperatureC651 Test Method for Flexural Strength of ManufacturedCarbon and GraphiteArticles Using Four-Point Loading atRoom TemperatureC747 Test Method for Moduli of Elasticity and FundamentalFrequencies of Carbon and Graphite Materials by SonicResonanceC1025 Test Method for Modulus of Rupture in Bending ofElectrode GraphiteC1039 Test Methods for Apparent Porosity,Apparent Spe-cific Gravity,and Bulk Density of Graphite Electrodes3.Terminology3.1 Definitions:3.1.1 core sample the portion of graphite obtained froman electrode by use of a sampling device such as described in4.1.3.1.2 test specimenan article prepared from a core sample.4.Significance and Use4.1 Core sampling is an acceptable way of obtaining a testspecimen without destroying the usefulness of the electrode.4.1.1 Test specimens obtained by this practice can be usedby producers and users of graphite electrodes for the purpose ofconducting the tests in Note 1 to obtain comparative physicalproperties.4.2 This practice may not provide a test specimen of theappropriate size(with respect to particle size/sample dimensionratios)to allow the determination of absolute property values.5.Apparatus5.1 Core Drill Bit,similar to that shown in Fig.1,driven bysuitable equipment.6.ProcedureNOTE2When core sampling a machined electrode,use caution toprevent damage to the socket threads and remove all dust from the threadswhen the coring operation is finished.6.1 The core sample shall be taken from either end of theelectrode as close to the center of the diameter as feasible.6.2 The core drill bit dimensions shall be such that a coresample with a minimum diameter of 50 mm and a minimumfinished length of 191 mm can be obtained.6.3 Place the core drill bit firmly against the graphite.6.4 Take care to maintain the bit level and true.Do not stopuntil the bit is embedded its full length.6.5 To remove the bit,pull and twist it by hand.Do notremove the bit while it is rotating.1This practice is under the jurisdiction of ASTM Committee D02 on PetroleumProducts,Liquid Fuels,and Lubricants and is the direct responsibility of Subcom-mittee D02.F0 on Manufactured Carbon and Graphite Products.Current edition approved Oct.1,2015.Published December 2015.Originallyapproved in 1974.Last previous edition approved in 2010 as C783 85(2010)1.DOI:10.1520/C0783-85R15.2For 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 Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.6 To remove the core sample,insert a wedge between itand the electrode until the core sample snaps.7.Keywords7.1 carbon;core;electrodes;graphite;sample;test speci-mensASTM 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 the riskof infringement of such rights,are entirely their