ASTM_D_5162_-_08.pdf

Designation:D516208Standard Practice forDiscontinuity(Holiday)Testing of Nonconductive ProtectiveCoating on Metallic Substrates1This standard is issued under the fixed designation D5162;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 covers procedures for determining discon-tinuities using two types of test equipment:1.1.1 Test Method ALow Voltage Wet Sponge,and1.1.2 Test Method BHigh Voltage Spark Testers.1.2 This practice addresses metallic substrates.For concretesurfaces,refer to Practice D4787.1.3 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.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 applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2G62 Test Methods for Holiday Detection in Pipeline Coat-ingsD4787 Practice for Continuity Verification of Liquid orSheet Linings Applied to Concrete Substrates2.2 NACE Standard:3RP018888 Discontinuity(Holiday)Testing of ProtectiveCoatings3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 discontinuity,as used in this standard,na flaw,void,crack,thin spot,foreign inclusion,or contamination in thecoating film that significantly lowers the dielectric strength ofthe coating film.A discontinuity may also be identified as aholiday or pinhole.3.1.2 holiday,as used in this standard,na term thatidentifies a discontinuity.3.1.3 holiday detector,as used in this standard,na devicethat locates discontinuities in a nonconductive coating filmapplied to an electrically conductive surface.3.1.4 pinhole,as used in this standard,na film defectcharacterized by small pore like flaws in the coating which,when extended entirely through the film,will appear as adiscontinuity.A pinhole in the finish coat may not appear as adiscontinuity.4.Significance and Use4.1 A coating is applied to a metallic substrate to preventcorrosion,reduce abrasion or reduce product contamination,orall three.The degree of coating continuity required is dictatedby service conditions.Discontinuities in a coating are fre-quently very minute and not readily visible.This practiceprovides a procedure for electrical detection of minute discon-tinuities in nonconductive coating systems.4.2 Electrical testing to determine the presence and numberof discontinuities in a coating film is performed on a noncon-ductive coating applied to an electrically conductive surface.The allowable number of discontinuities should be determinedprior to conducting this test since the acceptable quantity ofdiscontinuities will vary depending on coating film thickness,design,and service conditions.4.3 The low voltage wet sponge test equipment is generallyused for determining the existence of discontinuities in coatingfilms having a total thickness of 0.5 mm(20 mil)or less.Highvoltage spark test equipment is generally used for determiningthe existences of discontinuities in coating films having a totalthickness of greater than 0.5 mm(20 mil).4.4 Coatings that are applied at a thickness of less than 0.5mm(20 mil)may be susceptible to damage if tested with highvoltage spark testing equipment.Consult the coating manufac-turer for proper test equipment and inspection voltages.4.5 To prevent damage to a coating film when using highvoltage test instrumentation,total film thickness and dielectric1This practice is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.46 on Industrial Protective Coatings.Current edition approved June 1,2008.Published July 2008.Originally approvedin 1991.Last previous edition approved in 2001 as D5162 01.DOI:10.1520/D5162-08.2For 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.3Available from NACE International(NACE),1440 South Creek Dr.,Houston,TX 77084-4906,http:/www.nace.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 strength in a coating system shall be considered in selecting theappropriate voltage for detection of discontinuities.Atmo-spheric conditions shall also be considered since the voltagerequired for the spark to gap a given distance in air varies withthe conductivity of the air at the time the test is conducted.Suggested starting voltages are provided in Table 1.4.6 The coating manufacturer sh