ASTM E2479-2006 利用侧向纵波(L)测定聚乙烯容器壁中超声波速度的标准实施规程

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【英文标准名称】:StandardPracticeforMeasuringtheUltrasonicVelocityinPolyethyleneTankWallsUsingLateralLongitudinal(LCR)Waves
【原文标准名称】:利用侧向纵波(L)测定聚乙烯容器壁中超声波速度的标准实施规程
【标准号】:ASTME2479-2006
【标准状态】:现行
【国别】:
【发布日期】:2006
【实施或试行日期】:
【发布单位】:美国材料与试验协会(US-ASTM)
【起草单位】:E07.06
【标准类型】:(Practice)
【标准水平】:()
【中文主题词】:侧面的;测量;聚乙烯;容器壁;超声波学;速度;墙
【英文主题词】:
【摘要】:1.1Thispracticecoversaprocedureformeasuringtheultrasonicvelocitiesintheouterwallofpolyethylenestoragetanks.Ananglebeamlaterallongitudinal(LCR)waveisexcitedwithwedgesalongacircumferentialchordofthetankwall.Adigitalultrasonicflawdetectorisusedwithsending-receivingsearchunitsinthroughtransmissionmode.Theobservedvelocityistemperaturecorrectedandcomparedtotheexpectedvelocityforanew,unexposedsampleofmaterialwhichisthesameasthematerialbeingevaluated.ThedifferencebetweentheobservedandtemperaturecorrectedvelocitiesdeterminesthedegreeofUVexposureofthetank.1.2Thepracticeisintendedforapplicationtotheoutersurfacesofthewallofpolyethylenetanks.Degradationtypicallyoccursinanouterlayerapproximately3.2-mm[0.125-in.]thick.Sincethetechniquedoesnotinterrogatetheinsidewallofthetank,wallthicknessisnotaconsiderationotherthantobeawareofpossibleguided(Lamb)waveeffectsorreflectionsoffoftheinnertankwall.Nospecialsurfacepreparationisnecessarybeyondwipingtheareawithacleanrag.Insidewallpropertiesarenotimportantsincethelongitudinalwavedoesnotstrikethissurface.TheexcitationofLambwavesmustbeavoidedbychoosinganexcitationfrequencysuchthattheratioofwavelengthtowallthicknessisonefifthorless.1.3UVdegradationontheoutersurfacecausesastiffeningofthematerialandanincreaseinYoung''smodulusandthelongitudinalwavevelocity.
【中国标准分类号】:A82
【国际标准分类号】:23_020_10;83_080_01
【页数】:7P.;A4
【正文语种】: