ASTM_C_536_-_83_2014e1.pdf

Designation:C53683(Reapproved 2014)1Standard Test Method forContinuity of Coatings in Glassed Steel Equipment byElectrical Testing1This standard is issued under the fixed designation C536;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.1NOTEIntroduction added and units abbreviations corrected editorially in June 2014.INTRODUCTIONThis procedure is a high-voltage discharge test used to locate defects in glass-lined tanks bygrounding the base metal of the test specimen and brushing the test specimen with a probe connectedto the high-voltage side of the test instrument.If a discontinuity exists,a spark will discharge throughthe defect to the ground provided by the metal.1.Scope1.1 This test method covers the detection of discontinuitiesin the glass coating of glassed steel equipment where suchdiscontinuities would result in early failure due to the attack ofthe chemical contents of the vessel on the metal substrate.It isapplicable to(1)provide a manufacturing and inspection testof glassed-steel equipment designed for relatively mild,low-temperature corrosive service,and(2)the field testing ofsimilar equipment used in more severely corrosive environ-ment.NOTE1A manufacturing test method for the latter type of equipmentis described in Test Method C537.1.2 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.2.Referenced Document2.1 ASTM Standards:2C537 Test Method for Reliability of Glass Coatings onGlassed Steel Reaction Equipment by High Voltage3.Summary of Test Method3.1 The test method consists essentially of grounding themetal structure of the equipment being tested to the ground sideof a voltage generator and sweeping the surface of the glasswith a suitable probe electrically connected to the other side ofthe generator.Wherever a discontinuity exists,a discharge willgive a positive indication that such a discontinuity exists.Thevoltage is set at 5000 V in order to show existing discontinui-ties without breaking through the existing glass coating.Abuilt-in current limiting device ensures electrical safety for theoperator.4.Significance and Use4.1 This test method is designed to detect existing discon-tinuities in the glass coating of glassed steel equipment whilemaintaining a voltage low enough as to be unlikely to causebreakdown of the coating.The test is adaptable for manufac-turing inspection in the processing of equipment and for fielduse to find existing defects which can be“plugged”or repairedbefore serious damage is done to the equipment.As a means ofpositive detection,it is applicable to process studies,qualitycontrol,or specification.5.Definition5.1 glassed steel(glass-lined steel or glass-coated steel)designations generally applied to a class of porcelain enamelsthat have high resistance to chemical attack at elevatedtemperatures and pressures.6.Interferences6.1 Since the test method is electrical,it is necessary to havea good ground connection between the instrument and the1This test method is under the jurisdiction ofASTM Committee B08 on Metallicand Inorganic Coatingsand is the direct responsibility of Subcommittee B08.12 onMaterials for Porcelain Enamel and Ceramic-Metal Systems.Current edition approved May 1,2014.Published June 2014.Originallyapproved in 1964.Last previous edition approved in 2009 as C536 83(2009).DOI:10.1520/C0536-83R14E1.2For 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 metal substrate of the equipment being tested.It is alsonecessary that the surfaces of the glass be reasonably clean anddry.A wet surface will conduct enough voltage to any exposedmetal to give an indication of a“contact”over a large areainstead of at a specific area of discontinuity.Such a capacitancedischarge can be distinguished from a true failure by extendingover a large area instead of at local spots that could beidentified and marked for repair.7.Apparatus37.1 The test apparatus comprises a voltage stabilizingtransformer,a step-up transformer,a current-limitingresistance,a voltmeter and pilot light,along with a suitablyinsulated cable and probe handle equipped with interchange-able wire brush-type and point electrodes(see Fig.1 for