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(,210024):,,,,:;;;:U177;U178:A:10052748X(2008)0520257203DetectionofDefectLocationsinCoatingsonUndergroundPipelinesbyDCVGTechniqueCHAOLi2ping(QualitySupervisoryCentreofChemicalEquipment,Nanjing210024,China)Abstract:TheprincipleandmethodofthedetectiontechniqueofDCVGisintroduced.Throughchangingthesizeofdefects,environmentresistancerate,protectivecurrent,simulationtestsprovedthatDCVGtechniquecoulddetectthedefectlocations,andtherelationshipbetweenthedepthofundergroundpipelineandtheearthsurfacevoltagegradientscouldbeobtained.Keywords:buriedpipeline;anticorrosivecoating;detection;voltagegradient0,,,,,,,,11.1(DCVG)(Cu/CuSO4):2007205222;:2007206218[1],,,,,,11.2:;75229520085CORROSION&PROTECTIONVol.29No.5May2008,;,75mm;,;;;;;%IRDCVG,,,,:,22.1(1),20cm;(2);(3),;(4)0.1mV2.2:DJ26(1m,29cm,25cm),(27mm,2mm,950mm),,,,,ZF23;,,22.3,ABCD3mm5mm7mm,9mm,2.8cm,-0.012mA,165S/cm,(U/l,l,U),33,,-0.355mA,3200S/cm,,43mm,2.8cm,-0.355mA,3A:,650S/cm;B:,3200S/cm;C:,9000S/cm,,5:dEdl=i=1Li(1):dE/dI,mV/m;852:4,5,m;L,S/m;i,mA/m25,,,,,3520cm(),20cm,20cm33.1,,(),,x,Ua(x)[2]:Ua(x)=I4(1a2+x2+1a2+x2+4h2)(2):I,A;,m;h(),m;a(),m;xx,m3.2-0.012mA,165S/cm,,66-0.355mA,3200S/cm,7767,,,,,(1)(263)952::[1],.CO2[J].,1997,30(4):21-23.[2],.[J].,2000,20(5):77-79.[3]BurkePA.Synopsis:recentprogressintheunder2standingofCO2corrosion[C]//In:HauslerRH,Gid2dardHP.(Eds),AdvancesinCO2corrosionVol.1.Corrosion84,Houston,TX:NACEInternational,1993:1-18.[4]WaardC,LoztU.PredictionofCO2corrosionofcar2bonsteel[C]//AworkingpartyreportonpredictionCO2corrosioninoilandgascorrosionofcarbonsteel.Corrosion94,Houston,TX:NACEInternational,1994:1-21.[5]NewtonLE.CO2corrosioninoilandgasproduction[C]//Corrosion/1984,PaperNo.7.Houston:NationalAssociationofCorrosionEngineers,Texas,1984.(259),,,,,,,675.1cm,,,DCVG2m4(1),,(2),,(3),,:[1],,.DCVG[J].,2001(5):38.[2],.[J].,1998,10(2):63-65.,,,,,,,,,,97827212222045212008327136362:CO2