pipe thread-a管螺紋

1、Pipethread管螺紋管螺紋TwocommonpipethreadsizesexistthetaperedNationalPipeThread(NPT)thestraightNationalStardFreeFittingStraightMechanicalPipeThread(NPSM).Thetaperedthreadsarefjoiningsealingthestraightthreadsareonlyfjoining.The

2、Drysealthread(NPTF)allowsfjoiningwithoutsealants.ThreelesscommonthreadsexisttheGardenHoseThread(GHT)FireHoseCoupling(NST)BritishStardTaperPipeThread(BSPT).TheNPTNPTFthreadsareinterchangeablewithsealantssuchasPTFEtape.Non

3、eoftheotherthreadstardsareinterchangeable.FemaleNPTthreadscanbedesignatedas“FPT“maleNPTthreadscanbedesignatedas“MPT.“Pipesizesdonotrefertoanyphysicaldimensions.Theoutsidediameterofeachpipefittingmustbemeasuredcomparedtot

4、hetablefsizeidentification.Fexamplea34“NPTpipethreadhasanoutsidediameterof1.050inches.Eachthreadsizehasadefinednumberofthreadsperinch(TPI).The34“NPTpipethreadhas14threadsperinch.BoththeTPIODofthethreadarerequiredfpositiv

5、eidentificationofthreadsizebecauseseveralsizeshavethesameTPI.NominalPipeSize(NPT)ThreadsPerInchApproximateCaliperMeasurement18“270.38“14“180.55“38“180.63“12“140.80“34“141.00“1“11.51.25“114“11.51.55“112“11.51.80“2“11.52.3

6、0“DefinitionofpipethreadacronymsNPTNationalPipeThreadFPTFemalePipeThreadMPTMalePipeThreadPTFSAEshttapepipethreadNPTFAmericanNationaltaperpipethreadfdrysealpressuretightjointsNPSMAmericanNationalstraightpipethreadfmechani

7、caljointsNPSIAmericanNationalstraightintermediatepipethread規(guī)之峰部切斷大小另有規(guī)定.NPSC(NPSC(美制直管接頭用管用平行螺紋美制直管接頭用管用平行螺紋)如PS只有內(nèi)螺紋對(duì)方要用NPT.有效徑許容差與PS相同.正負(fù)同尺寸精度也大致類似.NPSC(NPSC(燃料管用耐密平行螺紋燃料管用耐密平行螺紋)主要用天軟材料外螺紋採(cǎi)用NPTF(幹封閉).有效徑許容差設(shè)于負(fù)邊公差定於NPC

8、之12(等於單邊公差)螺紋齒形與NPTF相同作成峰與根間無(wú)餘隙將推拔外螺紋緊配擴(kuò)大內(nèi)螺紋管口適合使用.NPSI(NPSI(中間管用耐密平行螺紋中間管用耐密平行螺紋)有效徑許容差在正負(fù)兩邊負(fù)邊.大公差和NPSF相同可以說(shuō)是近於基準(zhǔn)有效徑之中間的尺寸.對(duì)使用硬或脆性材料時(shí)多增加管壁厚度避免相配時(shí)擴(kuò)張過(guò)度而破壞而規(guī)定比NPSF稍大.NPSMNPSMANSI之機(jī)械接合用者裹具有比較精密配合之外螺紋內(nèi)螺紋兩方都是平行的組合之螺紋.精度略近PF之A

9、級(jí)有0.03以上之餘隙和美制螺紋之2A2相同.使用於無(wú)內(nèi)壓作用之鑄鐵管鋼管.黃銅等之接合.NPSLNPSLANSI之機(jī)械接合用者裹配合鎖緊帽之螺紋外螺紋.內(nèi)螺紋兩方都是平行的組合而餘隙有NPSM之大約24倍之松配合者.外螺紋爲(wèi)了能直接切削于標(biāo)準(zhǔn)尺寸管外面連最小有效徑也規(guī)定比基準(zhǔn)尺寸大.公差除小尺寸者外規(guī)定比NPSM大.NPSHNPSH使用於流通蒸氣.空氣.水等之軟管接頭之螺紋雖然外螺紋內(nèi)螺紋兩方都是平行的組合設(shè)以0.2~0.25之最小餘