英美螺纹资料.pdf

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1、ThreadThread1 DefinitionThe diameters, threads per inch (TPI) and thread pitch, etc. are necessary to completelyidentify a thread. In a shop, specialty gauges are required to accurately gauge or identifythreads. In the field, in the absence of these gauges, thread leaf gauges can be used toidentify

2、the Threads Per Inch (TPI) and the thread pitch. On threads you have determined tobe straight threads, a caliper can be used to measure the Outside Diameter of the Male(ODM) or the Inside Diameter of the Female (IDF). A caliper can also be used to takemeasurements of tapered thread diameters. Howeve

3、r, these are more difficult to definebecause of the taper. Fortunately, there are few tapered threads to deal with and these canusually be identified from the nominal ODM and the TPI.However, identifying the thread may not fully identify what is needed in a matingfitting. The application is the prim

4、ary limiting factor on the thread type used.limiting factor on the thread type used.We offer products with a wide variety of threads used with hose, pipe andhydraulics.When attempting to choose a fitting, it is always advisable to first identify thethread to which it must connect. This may entail ch

5、ecking with a fitting orequipment manufacturer.The fire hose thread specifications for some local municipal fireThe fire hose thread specifications for some local municipal fireequipment and hydrants may vary according to local specifications.equipment and hydrants may vary according to local specif

6、ications. Thesecan generally be most easily identified by contacting the local fire departmentresponsible for the hydrant. The most common thread used on fire equipment isNational Standard Thread (NST), also known as National Hose thread (NH).When it is not possible to identify the thread:1)1) Deter

7、mine the number of threads per inch by measuring the distancefrom peak of thread to peak of thread across the largest number ofwhole threads. Then divide the number of threads by the measurement.(This will provide the TPI).2)2) Check to see if the thread is straight or tapered.a)a) Straight ThreadsM

8、easure the Outside Diameter of the Male (ODM) or the InsideDiameter of the Female (IDF), from peak of thread to peak of thread.b)b) Tapered ThreadsMeasure the Outside Diameter of the Male (ODM) at the large endand the small end, or the Inside Diameter of the Female (IDF) at thelarge end and the smal

9、l end, from peak of thread to peak of thread.Then measure the Outside Diameter (OD) of the unthreaded pipe.Once the application and these two pieces of information have beendetermined, the thread can generally be determined. When in doubt,contactcontactthe manufacturer.the manufacturer.Straight Thre

10、adStraight ThreadMaleMaleFemaleFemaleTapered ThreadTapered ThreadMaleMaleFemaleFemaleThreading InformationThreading InformationAbbreviationAbbreviationSystem NameSystem NameB British S Standard P PipeP ParallelCompatibilityCompatibilityMale BSPP with Female BSPPBSPPBSPPFemale BSPP with Male BSPPFema

11、le BSPP with Male BSPTrMale BSPTr with Female BSPTrB British S Standard P PipeT TaperMale BSPTr with Female BSPPFemale BSPTr with Male BSPTrFemale BSPTr not compatiblewith Male BSPP1Male NH (NST) with 1 FemaleNH (NST)American Standard FireHose Thread (1 NationalCHTCHTHose Thread is C ChemicalH Hose

12、T Thread, also knownas Booster Hose Thread)1 Female NH (NST) with 1 MaleNH (NST)1 Thread is used on both hose & 1 hose.Not compatible with othersystemsMale GHT with Female GHTFemale GHT with Male GHTGHT GGHT Garden H Hose T ThreadThread is the same for all sizehose.Not compatible with othersystemsGe

13、neric name for Straight PipeIPS IIPS Iron P Pipe S Straight ThreadThreadSee NPSH for compatibilityJIC JJIC Joint I Industrial C CommitteeUsed with other mating JICthreadsMale NH (NST) with Female NHAmerican Standard FireNHNHororNSTNSTHose Coupling Thread(N National H Hose thread alsoknown as N Natio

14、nalS Standard T Thread(NST)Female NH (NST) with Male NH(NST)Not compatible with othersystemsThread pitch and diameters of fireWasherWasherWasherWasherWasherMechanicalWasherWasherSeal MethodSeal MethodWasherWasherWasherThreadWasherThreadBSPTrBSPTrthreads may vary according tolocal and municipal regul

15、ations.Male NPT with Female NPTMale NPT with Female NPTFMale NPT with Female NPSMAmerican Standard TaperNPTNPTPipe Thread (N National P PipeT ThreadMale NPT with Female NPSHFemale NPT with Male NPTFemale NPT with Male NPTFFemale NPT not compatible withMale NPSM or Male NPSHMale NPTF with Female NPTF

16、Male NPTF with Female NPTMale NPTF with Female NPSMMale NPTF with Female NPSHAmerican Standard TaperNPTFNPTFPipe Fuel Dryseal Thread(N National P Pipe T TaperedF Fine)Female NPTF with Male NPTFFemale NPTF with Male NPTFemale NPTF with Male NPSM orMale NPSHNote: NPTF with NPTF threadsdo not require s

17、ealant for theinitial use. After that, sealant isrequired.Male NPSH with Female NPSHAmerican Standard StraightFemale NPSH with Male NPSHPipe for Hose CouplingsFemale NPSH with Male NPT(N National P Pipe S StraightFemale NPSH with Male NPTFH Hose)Female NPSH with Male NPSMMale NPSM with Female NPSMAm

18、erican Standard StraightMale NPSM with Female NPSHNPSMNPSMMechanical Joints(N National P Pipe S StraightMMechanical)Female NPSM with Male NPSMFemale NPSM with Male NPTFemale NPSM with Male NPTFTIPT TTIPT Tapered I Iron P Pipe T ThreadGeneric name for Tapered PipeThreadWasherWasherWasherWasherWasherS

19、eal can beeithermechanical orwasher.Mating fittingsmust be ofsame typeThreadThreadThreadWasherWasherThreadThreadThreadThreadWasherWasherThreadThreadNotNotCompatibleCompatibleNPSHNPSHThread DimensionsThread DimensionsNominal Dimensions of Standard ThreadsNominal Dimensions of Standard ThreadsSizeSize

20、PipePipeNPTNPTNPSH NPSMNPSH NPSMIDFIDF(Min)(Min)TPITPIODMODMIDFIDFO. D.O. D.TPITPITPITPIODMODM(Max)(Max)(Max)(Max) (Min)(Min)270.397 0.3581/81/8.405 27- - - -180.526 0.4681/41/4.504 18- - - -180.662 0.6033/83/8.675 18- - - -1/21/2.840 14140.8248 0.7395140.823 0.7473/43/41.050 14 141.0353 0.9500141.0

21、34 0.958111.315 11.511.5 1.2951 1.1921 11.5 1.293 1.2011-1- 1.660 11.511.5 1.6399 1.5369 11.5 1.638 1.5461-1- 1.900 11.511.5 1.8788 1.7758 11.5 1.877 1.785222.375 11.511.5 2.3528 2.2498 11.5 2.351 2.2592.841 2.7083.467 3.3344.466 4.3335.528 5.3956.585 6.4522-2- 2.875 8- - - -833445566883.500 8- - -

22、-84.500 8- - - -85.563 8- - - -86.625 8- - - -88.625 8- - - - - - -1010 10.750 8- - - - - - -1212 12.750 8- - - - - - -ODM = Outside Diameter of MaleIDF = Inside Diameter of FemaleTPI = Threads per InchGHT () = 1.0625 ODM, 11- TPIPipePipeO. D.O. D.TPITPI1/81/8.4051/41/4.5043/83/8.675NH (NST)NH (NST)

23、ODMODMIDFIDFBSPP (Parallel)BSPP (Parallel)TPITPIODMODMIDFIDFBSPTrBSPTr(Tapered)(Tapered)TPITPI281919SizeSize(Max)(Max) (Min)(Min)(Max)(Max) (Min)(Min)0.383 0.3370.516 0.4500.656 0.588- - - - - - - - - - - - -1/21/2.840- - - - - -0.825 0.7331.041 0.9501414111111111111113/43/4 1.050 8 1.3751.2246111.3

24、15 8 1.3751.2246 11 1.309 1.1931.650 1.5341-1- 1.660- - - - -1-1- 1.900 9 1.9901.8577 11 1.882 1.766222.375- - - - -2.347 2.2312-2- 2.875 7.5 3.0682.9104 11 2.960 2.84433443.500 6 3.6233.5306 11 3.460 3.3444.500 4 5.0104.7111 11 4.450 4.334- -4- -4- -4 5.7605.46115566- - - -11115.563 4 6.2605.9602 1

25、1 5.450 5.3596.625 4 7.0256.7252 11 6.450 6.359ODM = Outside Diameter of MaleIDF = Inside Diameter of FemaleTPI = Threads per InchGHT () = 1.0625 ODM, 11- TPINOTE: Female NPT (Tapered Pipe) thread is not available onNOTE: Female NPT (Tapered Pipe) thread is not available onhose swivel nuts.hose swiv

26、el nuts.Normal Engagement LengthNormal Engagement Lengthof NPT Thread in Inches (A) *of NPT Thread in Inches (A) *SizeSize1/8 1/4 3/81/8 1/4 3/8 1/21/2 3/43/4111-1-1-1-22LengthLength 1/4 3/8 3/81/2 9/16 11/16 11/16 11/16 3/4Size 2-Size 2-334455668810 1210 12LengthLength 15/16 1 1-1/81-1/4 1-5/16 1-7

27、/16 1-5/8 1-3/4* * Dimensions given do not allow for variations in tapping or threadingThread Sealing TipsThread Sealing TipsThread Seal TypeThread Seal TypeA seal is obtained by applying asealant to the male thread beforeengaging.The sealant is used to prevent spiralleakage.Thread tape or paste is

28、the preferredsealant in this type of application.Washer Seal TypeWasher Seal TypeA seal is obtained when the malethread is tightened down onto thewasher of the female assembly.The washer should be inspectedregularly and replaced as needed toprevent leakage.Mechanical Seal TypeMechanical Seal TypeA s

29、eal is obtained through metal tometal contact or metal to sealcontact, for example JIC couplingshave a metal to metal seal. EZ-BossGround Joint couplings have a metalto seal contact (shown at left).The couplings should be retightenedas needed to prevent leakage.More Thread Sealing Tips.More Thread S

30、ealing Tips.Sealing NPT threads can be an exasperating experience if certain techniquesSealing NPT threads can be an exasperating experience if certain techniquesare not followed. The following tips will help alleviate many common problemsare not followed. The following tips will help alleviate many

31、 common problemsin thread sealing:in thread sealing:1.1. Always use some type ofsealant (tape or paste) andapply sealant to male threadonly. If using a hydraulic sealant,allow sufficient curing timebefore system is pressurized.2.2. When using tape sealant,wrap the threads in a clockwisemotion starti

32、ng at the first threadand, as layers are applied, worktowards the imperfect(vanishing) thread. If the systemthat the connection being madeto cannot tolerate foreign matter(i.e. air systems), leave the firstthread exposed and apply thetape sealant as outlined above.3.3. When using paste sealant,6.6.

33、For sizes 2 and below, tapeor paste usually performssatisfactorily. When using threadtape, four wraps (covering allnecessary threads) is usuallysufficient.7.7. For sizes 2- and above,thread paste is recommended. Ifthread tape is used, eight wraps(covering all necessary threads)is usually sufficient.

34、 Apply morewraps if necessary.8.8. For stubborn to seal threads,apply a normal coating of threadpaste followed by a normal layerof thread tape.9.9. For extremelyextremely stubborn toseal threads, apply a normalapply to threads with a brush,using the brush to work thesealant into the threads. Applyen

35、ough sealant to fill in all thethreads all the way around.4.4. When connecting onestainless steel part to anotherstainless steel part that willrequire future disassembly, usea thread sealant that is designedfor stainless steel. This stainlesssteel thread sealant is alsouseful when connectingaluminum

36、 to aluminum thatneeds to be disconnected in thefuture. These two materials galleasily, and if the correct sealantis not used, it can be next toimpossible to disassemble.5.5. When connecting parts madeof dissimilar metals (i.e. steel &aluminum), standard tape orpaste sealant usually performssatisfac

37、torily.coating of thread paste followedby a single layer of gauzebandage followed by a normallayer of thread tape.Caution!Caution!When this procedure is done,the connection becomespermanent. Extreme measureswill be necessary to disconnectthese components. All othermeasures to seal the threadsshould

38、be explored prior to theuse of this technique.10.10. Over-tightening threads canbe just as detrimental asinsufficient tightening. For sizes2 and below, hand tighten thecomponents and, with a wrench,tighten 3 full turns. for sizes 2-and above, hand tighten thecomponents and, with a wrench,tighten 2 f

39、ull turns.2 Pipe Thread StandardsTwo common pipe thread standards exist:National Pipe Thread (NPT) - a tapered threadNational Standard Free-Fitting Straight Mechanical Pipe Thread (NPSM) - astraight threadLess common standards also exist:Garden Hose Thread (GHT)Fire Hose Coupling (NST)British Standa

40、rd Taper Pipe Thread (BSPT)Female NPT threads can be designated as FPT and male NPT threads can be designatedas MPT. I have also seen female NPT threads designated as FNPT and male as MNPT.Straight Versus Tapered ThreadsThreaded pipe can be connected to join things together, which does not necessari

41、lyproduce a leakproof seal, or they can be joined and sealed.Straight threads only provide a mechanical junction. They dont really seal.Tapered threads both join and seal. The deeper you drive them, the tighter the seal.Pipe Thread TapeWhenever you want a good seal when screwing together pipes and f

42、ittings, use pipe threadtape. This is usually made of PTFE, the most famous brand of which is Teflon.In addition to sealing, pipe thread tape also lubricates the joint, which:makes it easier to tighten itmakes it easier to disassemble the joint in the futurereduces/eliminates thread galling Thread g

43、alling is when threads weldthemselves together. This is more common with pipes and fasteners made fromalloys that protect themselves from corrosion by developing their own oxidesurface film, like aluminum and stainless steel.Standard Pipe SizesPipe sizes do not refer to any physical dimension of mod

44、ern pipe. If you measure a pieceof 1/4 NPT pipe, you will have a hard time finding anything there that measures 1/4.Historical note:The sizes derive from the days when pipes were made of iron, pipe walls wererather thick, and the internal diameter (ID) was standardized. At that time,if you specified

45、 a 1/2 pipe, it had an internal diameter of 1/2, and an outerdiameter that depended on the thickness of the wall.Nowadays, the standards measure the threaded part of the pipe, the outer diameter(OD). This lets thin-wall and thick-wall pipe use the same fittings.But we kept the same names, so when yo

46、u say 1/2 pipe, you get a pipe whose outerdiameter is the same as that of an old-fashioned iron pipe whose inner diameterwas 1/2.In order to get the right size, you should measure the outer diameter (OD) of the pipe,and look it up in a table to find out what it is officially called. Its also a goodi

47、dea to measure the threads per inch (TPI). The combination of OD and TPI provide positiveidentification of standard pipe sizes.OD FractionOD Decimal Normal depth(approximate) (actual)for tight joint5/1613/3235/6443/6427/321-3/641-5/161-21/321-29/322-3/82-7/83-1/244-1/20.31250.4050.5400.6750.8401.0501.3151.6601.9002.3752.8753.54.04.50.26110.26390.40180.40780.53370.54570.68280.70680.72350.75651.13751.20001.25001.3000Pipe Thread Size Threads per Inch1/161/81/43/81/23/411-1/41-1/222-1/233-1/243,27271818141411-1/211-1/211-1/211-1/28888