Designation:G18−07(Reapproved2013)StandardTestMethodforJoints,Fittings,andPatchesinCoatedPipelines1ThisstandardisissuedunderthefixeddesignationG18;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethoddescribesdeterminationofthecom-parativecorrosionpreventativecharacteristicsofmaterialsusedforapplicationstojoints,couplings,irregularfittings,andpatchedareasincoatedpipelines.Thetestmethodisapplicabletomaterialswhoseprincipalfunctionistoactasbarriersbetweenthepipesurfaceandsurroundingsoilenvironment.1.2Thetestmethoddescribedemploysmeasurementsofleakagecurrent,capacitance,anddissipationfactortoindicatechangesintheinsulatingeffectivenessofjointandpatchingmaterials.1.3ThevaluesstatedinSIunitsaretoberegardedasthestandard.Thevaluesgiveninparenthesesareforinformationonly.1.4Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.1.5ThevaluesstatedinSIunitstothreesignificantdeci-malsaretoberegardedasthestandard.Thevaluesgiveninparenthesesareforinformationonly.2.ReferencedDocuments2.1ASTMStandards:2G12TestMethodforNondestructiveMeasurementofFilmThicknessofPipelineCoatingsonSteel(Withdrawn2013)33.SummaryofTestMethod3.1Thetestmethodconsistsofanimmersiontestwherecoatedpipespecimens,eachcontainingasimulatedjoint,tee,orpatchedarea,aresuspendedinanelectrolyteandplacedundercathodicprotectionbyconnectingthespecimenstothenegative(−)terminalofa6-Vd-cpowersupply(seeFig.1).Ananode,alsoimmersedintheelectrolyteandconnectedtothepositive(+)terminalofthepowersupply,completesthetestcircuit.Jointorpatchperformanceisfollowedthroughperiodicdeterminationsofleakagecurrentmeasuredasvoltagedrop...
