EffectoflengthofthinningareaonthefailurebehaviorofcarbonsteelpipecontainingadefectofwallthinningOriginalResearchArticle

Thepresentstudyperformedpipefailuretestsusing102mm-Sch.80carbonsteelpipewithvarioussimulatedwallthinningdefects,toinvestigatetheeffectofaxiallengthofwallthinningandinternalpressureonthefailurebehaviorofpipethinnedbyflowacceleratedcorrosion(FAC).Thetestswereconductedunderloadingconditionsoffour-pointbendingwithandwithoutinternalpressure.Theresultsshowedthatafailuremodeofpipewithadefectdependedonthemagnitudeofinternalpressureandaxialthinninglengthaswellasstresstypeandthinningdepthandcircumferentialangle.Bothloadcarryingcapability(LCC)anddeformationcapability(DC)weredependedonstresstypeinthethinningareaanddimensionsofthinningdefect.Forapplyingtensilestresstothethinnedarea,thedependenceofLCContheaxiallengthofwallthinningwasdeterminedbycircumferentialthinningangle,andtheDCwasproportionallyincreasedwithincreaseinaxiallengthofwallthinningregardlessofthecircumferentialangle.Forapplyingcompressivestresstothinnedarea,however,theLCCwasdecreasedwithincreaseinaxiallengthofthethinnedarea.Also,theeffectofinternalpressureonfailurebehaviorwascharacterizedbyfailuremodeofthinnedpipe,anditpromotedcrackoccurrenceandmitigatedalocalbucklingofthethinnedarea.