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没有8“SCH4012”8"
SCH4014"
的规格!
NominalPipeSize
FromWikipedia,thefreeencyclopedia
NominalPipeSize(NPS)isaNorthAmericansetofstandardsizesforpipesusedforhighorlowpressuresandtemperatures.[1]Pipesizeisspecifiedwithtwonon-dimensionalnumbers:
anominalpipesize(NPS)fordiameterbasedoninches,andaschedule(Sched.orSch.)forwallthickness.NPSisoftenincorrectlycalledNationalPipeSize,duetoconfusionwithnationalpipethread(NPT).TheEuropeandesignationequivalenttoNPSisDN(diamè
trenominal/nominaldiameter),inwhichsizesaremeasuredinmillimetres.[2]ThetermNB(nominalbore)isalsofrequentlyusedinterchangeablywithNPS.
Contents
▪1History
▪2Application
3NPStablesforselectedsizes
3.1NPS⅛toNPS3½
3.2NPS4toNPS9
3.3NPS10toNPS24
3.4NPS26toNPS36
3.5Additionalsizes(NPS)
▪4Seealso
▪5Notes
6References
6.1Bibliography
▪7Externallinks
[edit]History
InMarch1927,theAmericanStandardsAssociationauthorizedacommitteetostandardizethedimensionsofwroughtsteelandwroughtironpipeandtubing.Atthattimeonlyasmallselectionofwallthicknesseswereinuse:
standardweight(STD),extra-strong(XS),anddoubleextra-strong(XXS),basedontheironpipesize(IPS)systemoftheday.Howeverthesethreesizesdidnotfitallapplications.Thecommitteesurveyedtheindustryandcreatedasystemofschedulenumbersthatdesignatedwallthicknessesbasedonsmallerstepsbetweensizes,[3]althoughIPSandNPSnumbersremainequivalent.
Theoriginalintentwasthateachschedulewouldrelatetoagivenpressurerating,howeverthenumbersdeviatedsofarfromwallthicknessesincommonusethatthisoriginalintentcouldnotbeaccomplished.[3][note1]Also,in1939,itwashopedthatthedesignationsofSTD,XS,andXXSwouldbephasedoutbyschedulenumbers,howeverthoseoriginaltermsarestillincommonusetoday(althoughsometimesreferredtoasstandard,extra-heavy(XH),anddoubleextra-heavy(XXH),respectively).Sincetheoriginalscheduleswerecreated,therehavebeenmanyrevisionsandadditionstothetablesofpipesizesbasedonindustryuseandonstandardsfromAPI,ASTM,andothers.[3]
Stainlesssteelpipes,whichwerecomingintomorecommonuseinthemid20thcentury,permittedtheuseofthinnerpipewallswithmuchlessriskoffailureduetocorrosion.By1949thinnerschedules5Sand10S,whichwerebasedonthepressurerequirementsmodifiedtothenearestBWGnumber,hadbeencreated,andother"
S"
sizesfollowedlater.Duetotheirthinwalls,thesmaller"
sizescannotbethreadedtogetheraccordingtoASMEcode,butmustbefusionwelded.[4]
[edit]Application
BasedontheNPSandscheduleofapipe,thepipeoutsidediameter(OD)andwallthicknesscanbeobtainedfromreferencetablessuchasthosebelow,whicharebasedonASMEstandardsB36.10MandB36.19M.Forexample,NPS14Sch40hasanODof14inchesandawallthicknessof0.437inches.HowevertheNPSandODvaluesarenotalwaysequal,whichcancreateconfusion.
▪ForNPS⅛to12inches,theNPSandODvaluesaredifferent.Forexample,theODofanNPS12pipeisactually12.75inches.TofindtheactualODforeachNPSvalue,refertothetablesbelow.(Notethatfortubing,thesizeisalwaystheactualOD.)
▪ForNPS14inchesandup,theNPSandODvaluesareequal.Inotherwords,anNPS14pipeisactually14inchesOD.
ThereasonforthediscrepancyforNPS⅛to12inchesisthattheseNPSvalueswereoriginallysettogivethesameinsidediameter(ID)basedonwallthicknessesstandardatthetime.However,asthesetofavailablewallthicknessesevolved,theIDchangedandNPSbecameonlyindirectlyrelatedtoIDandOD.
ForagivenNPS,theODstaysfixedandthewallthicknessincreaseswithschedule.Foragivenschedule,theODincreaseswithNPSwhilethewallthicknessstaysconstantorincreases.UsingequationsandrulesinASMEB31.3ProcessPiping,itcanbeshownthatpressureratingdecreaseswithincreasingNPSandconstantschedule.[note1]
Somespecificationsusepipeschedulescalledstandardwall(STD),extrastrong(XS),anddoubleextrastrong(XXS),althoughtheseactuallybelongtoanoldersystemcalledironpipesize(IPS).TheIPSnumberisthesameastheNPSnumber.STDisidenticaltoSCH40S,and40Sisidenticalto40forNPS1/8toNPS10,inclusive.XSisidenticaltoSCH80S,and80Sisidenticalto80forNPS1/8toNPS8,inclusive.XXSwallisthickerthanschedule160fromNPS1/8"
toNPS6"
inclusive,andschedule160isthickerthanXXSwallforNPS8"
andlarger.
The"
designation,forexample"
NPSSch10S"
mostoftenindicatesstainlesssteelpipes.Howeversomestainlesssteelpipesareavailableinsteeldesignations,sostrictlyspeakingthe"
designationonlydifferentiatesB36.19MpipefromB36.10Mpipe.[1]
Bothpolyvinylchloridepipe(PVC)andchlorinatedpolyvinylchloridepipe(CPVC)aremadeinNPSsizes.
[edit]NPStablesforselectedsizes
[edit]NPS⅛toNPS3½
NPS[5]
DN
[2]
OD
[in(mm)]
Wallthickness
SCH5
SCH10s/10
SCH30
SCH40s/40
/STD
SCH80s/80
/XS
SCH120
SCH160
XXS
⅛
6
0.405(10.29)
0.035(0.889)
0.049(1.245)
0.057(1.448)
0.068(1.727)
0.095(2.413)
—
¼
8
0.540(13.72)
0.065(1.651)
0.073(1.854)
0.088(2.235)
0.119(3.023)
⅜
10
0.675(17.15)
0.091(2.311)
0.126(3.200)
½
15
0.840(21.34)
0.083(2.108)
0.109(2.769)
0.147(3.734)
0.188(4.775)
0.294(7.468)
¾
20
1.050(26.67)
0.113(2.870)
0.154(3.912)
0.219(5.563)
0.308(7.823)
1
25
1.315(33.40)
0.114(2.896)
0.133(3.378)
0.179(4.547)
0.250(6.350)
0.358(9.093)
1¼
32
1.660(42.16)
0.117(2.972)
0.140(3.556)
0.191(4.851)
0.382(9.703)
1½
40
1.900(48.26)
0.125(3.175)
0.145(3.683)
0.200(5.080)
0.281(7.137)
0.400(10.160)
2
50
2.375(60.33)
0.218(5.537)
0.343(8.712)
0.436(11.074)
2½
65
2.875(73.03)
0.120(3.048)
0.203(5.156)
0.276(7.010)
0.300(7.620)
0.375(9.525)
0.552(14.021)
3
80
3.500(88.90)
0.216(5.486)
0.350(8.890)
0.438(11.125)
0.600(15.240)
3½
90
4.000(101.60)
0.226(5.740)
0.318(8.077)
0.636(16.154)
[edit]NPS4toNPS9
SCH20
SCH60
SCH100
SCH140
XXS[5]
4
100
4.500(114.30)
0.237(6.020)
0.337(8.560)
0.437(11.100)
0.531(13.487)
0.674(17.120)
4½
115
5.000(127.00)
0.247(6.274)
0.355(9.017)
0.710(18.034)
5
125
5.563(141.30)
0.134(3.404)
0.258(6.553)
0.500(12.700)
0.625(15.875)
0.750(19.050)
150
6.625(168.28)
0.280(7.112)
0.432(10.973)
0.562(14.275)
0.718(18.237)
0.864(21.946)
7[5]
7.625(193.68)
0.301(7.645)
0.875(22.225)
200
8.625(219.08)
0.148(3.759)
0.277(7.036)
0.322(8.179)
0.406(10.312)
0.593(15.062)
0.812(20.625)
0.906(23.012)
9[5]
9.625(244.48)
0.342(8.687)
[edit]NPS10toNPS24
SCH5s
SCHrichs
SCH10
SCH40s/STD
250
10.75(273.05)
0.165(4.191)
0.307(7.798)
0.365(9.271)
12
300
12.75(323.85)
0.156(3.962)
0.180(4.572)
0.330(8.382)
14
350
14.00(355.60)
0.312(7.925)
16
400
16.00(406.40)
18
450
18.00(457.20)
500
20.00(508.00)
24
600
24.00(609.60)
SCH40
SCH80s/XS
SCH80
0.843(21.412)
1.000(25.400)
1.125(28.575)
0.687(17