2023年全國碩士研究生考試考研英語一試題真題(含答案詳解+作文范文)_第1頁
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1、StardPipeThreadsTherearemanypipethreadspecificationsbuttheyfallintooneoftwocategies:TheNthAmericanUSStardtheRestofthewld.TheUShastheNationalStardPipeThreaddesignatedNPTavariationofitthedrysealthreaddesignatedNPTF.Theyare

2、reallythesamethread.Thedrysealthreaddiffersinthattherootsofthethreadsareslightlymedthanthecrests.Thedrysealwasdesignedtobesealedwithoutthreadsealant.Ifyouaregoingtousethreadsealantanywaythefittingscanbeusedinterchangeabl

3、y.SometimesyouwillseeNPTFusedtodesignateNationalPipeThreadFemaleNPTMfNationalPipeThreadMale.Ifsomeonetriestotellyouthisinsultthemproperlyfbeingidiots.TherestofthewldisbasedoffoftheBritishStardPipeThreads.Therearetapereds

4、traightthreadversions.SometimesyouwillhearthemcalledBSPTBSPPrespectively.TheBritishdontcalltheirthreadsthat.Theydesignatethemas“R““RTr“respectively.GermanyFranceJapanallhavetheirownnamesfthethreads.Theyareshowninthetable

5、.TheNationalStardtheBritishStardalsodifferinthattheirpitchesthreadsperinchareslightlydifferent.Ifyoupickuptwofittingstheywillalmostgotogether.Donttrytoputthemtogetherthough.Atbestyoulljustruinbothfittings.Onlythenominal1

6、2“34“havethesamepitch.Stilldonttrytoputthemtogether(itmaywk)becausethethreadfmsareslightlydifferentyoumayhaveadifficulttimeputtingthemtogether.Whythetwothreadsystemsaresimilarbutnotquitethesameisamysterytome.Mythey(being

7、anAmerican)isthatitwasinventedheretheBritscouldntstitsotheychangeditjustslightlysotheywouldneverhavetouseanAmericanmadeproduct.TherestoftheEuropeans(Japan)couldntstusinganEnglishthreadfurtherchangedthenamecalleditmetric.

8、ImsuretherestofthewldwouldsaythatitwastheAmericansthatchangeditmadeourownstardjusttobedifferent.IfwedidImsurewehadagoodreason.PipeThreadCrossReferenceNthAmericanStardTheRestoftheWldNationalStardPipeThreadBritishStardPipe

9、Parallel(BSPPBSPF)BritishStardPipeTapered(BSPT)NominalSize(inches)StardTaperPipeThreadDrysealPipeThreadTPIGermanyFranceJapanBritainGermanyFranceJapanBritainTPI116116NPT116NPTF271818NPT18NPTF27G18G18PF18R18TrR18kegG18coPT

10、18R18281414NPT14NPTF18G14G14PF14R14TrR14kegG14coPT14R14193838NPT38NPTF18G38G38PF38R38TrR38kegG38coPT38R38191212NPT12NPTF14G12G12PF12R12TrR12kegG12coPT12R121458G58G58PF58R58TrR58kegG58coPT58R58143434NPT34NPTF14G34G34PF34R

11、34TrR34kegG34coPT34R341478G78G78PF78R78TrR78kegG78coPT78R781411NPT1NPTF11.5G1G1PF1R1TrR1kegG1coPT1R111114114NPT114NPTF11.5G114G114PF114R114TrR114kegG114coPT114R11411112112NPT112NPTF11.5G112G112PF112R112TrR112kegG112coPT1

12、12R1121122NPT2NPTF11.5G2G2PF2R2TrR2kegG2coPT2R211212212NPT212NPTF8PipeTubingSizesPipeisidentifiedbyitsnominalsize.iginallytheODofpipewasdefinedbyitsID.Givenawallthicknesssuitabletoholdingtherequiredpressure(usingthemater

13、ialsatthetime)theODwasdetermined.WiththeadventofmodernsteelstheODhasremainedconstanttheIDhasincreased.Differentwallthicknessesarenowavailabletohledifferentpressures.TheyaredefinedbytheASMEBoilerPressureVesselCodearedesig

14、natedastheSchedulenumber.Schedules204080160definedbutthemostcommonareSchedules4080.TubingisdesignatedbyitsOD.A12“tubehaa12“outsidediameter.Itsinsidediameterissomethingless.HoseontheotherhisdesignatedbyitsID.A12“hosehasa1

15、2“insidediameter.Itiscommonpracticewhenplumbingsystemswithhosepipetubingtousetubingthenextnominalsizeupfromthehose.Hosepipearetypicallyplumbedatthesamenominalsize.EventhoughmostSchedule4080pipehasalargerIDitisalsorougher

16、theincreaseddiameterallowsftheincreasedfriction.ConductSizeComparisonAllDimsinInches(1)PipeSteelTubing(2)NylonTubing(3)Hose(4)NominalSizeSch40IDSch.80IDODIDODIDODIDOD18.269.215.405.069.125.085.125.12514.364.302.540.194.2

17、50.125.250.250.53138.493.423.675.319.375.275.375.375.65612.622.546.840.430.500.375.500.500.87534.824.7421.050.620.750.750.7501.27611.049.9571.315.8341.0001.0001.0001.5281141.3801.2171.6601.1721.2501.2501.2501.9301121.610

18、1.5001.9001.2601.5001.5001.5002.17422.0671.9392.3751.6882.0002.0002.0002.764Notes:1.Notolerancesexpressedimplied.Dimensionsgivenfrefrenceonly.Nylontubinghosedimensionsmayvarybymanufacturerproductseries.2.Wallsizedfminimu

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