1、Designation:D478713(Reapproved 2018)Standard Practice forContinuity Verification of Liquid or Sheet Linings Applied toConcrete Substrates1This standard is issued under the fixed designation D4787;the number immediately following the designation indicates the year oforiginal adoption or,in the case o
2、f 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 that may be used toallow the detection of discontinuities in noncond
3、uctive liningsor other non-conductive coatings applied to concrete sub-strates.1.2 Discontinuities may include pinholes,internal voids,holidays,cracks,and conductive inclusions.1.3 This practice describes detection of discontinuities uti-lizing a high voltage spark tester using either pulsed orconti
4、nuous dc voltage.NOTE1For further information on discontinuity testing refer toNACE Standard SP0188-2006 or Practice D5162.1.4 This practice describes procedures both with and with-out the use of a conductive underlayment.1.5 The values stated in SI units are to be regarded asstandard.The values giv
5、en in parentheses are for informationonly.1.6 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 o
6、f regulatory limitations prior to use.For a specific hazard statement,see Section 7.1.7 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,Guid
7、es and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D5162 Practice for Discontinuity(Holiday)Testing of Non-conductive Protective Coating on Metallic SubstratesG62 Test Methods for Holiday Detection in Pipe
8、line Coat-ings2.2 NACE Standards:3SP0188-2006 Discontinuity(Holiday)Testing of ProtectiveCoatings3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 conductive underlayment,na continuous layer ap-plied to the prepared concrete surface prior to the application ofa nonconductive lini
9、ng layer(s)that will allow high voltagespark testing for discontinuities in the lining,as it will conductthe current present when the spark is generated.3.1.2 current sensitivity,nsome high voltage testers haveadjustable current sensitivity that can be used to prevent lowlevels of current flow activ
10、ating the audible alarm.The alarmsensitivity control sets the threshold current at which theaudible alarm sounds.If the high voltage can charge the lining,a small amount of current will flow while this charge isestablished.If the lining contains a pigment that allows alow-level leakage current to fl
11、ow from the probe while testingthe threshold current can be set so that the alarm does notsound until this current is exceeded,that is,when a holiday orflaw is detected.Increasing the current threshold setting makesthe instrument less sensitive to this low level current flow,decreasing the current t
12、hreshold setting makes the instrumentmore sensitive to current flow.1This 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
13、 Sept.1,2018.Published September 2018.Originallyapproved in 1988.Last previous edition approved in 2013 as D4787 08(2013).DOI:10.1520/D4787-13R18.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards vol
14、ume 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 StatesThis inte
15、rnational standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Commi
16、ttee.1 3.1.3 discontinuity,na localized lining site that has adielectric strength less than a determined test voltage.3.1.4 high voltage spark tester,nan electrical device(producing a voltage in excess of 500 V)used to locatediscontinuities in a nonconductive protective coating applied toa conductive substrate.The high voltage is applied to thecoating or lining using an exploring electrode and any currentresulting from the high voltage passing through a discontinuityin the coating or lining is p
