1、Designation: F 1498 08An American National StandardStandard Specification forTaper Pipe Threads 60 for Thermoplastic Pipe and Fittings1This standard is issued under the fixed designation F 1498; the number immediately following the designation indicates the year oforiginal adoption or, in the case o
2、f revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This specification establishes requirements for dimen-sions and gaging of taper pipe threads
3、 used on threaded plasticpipe and fittings.1.2 Threads meeting this specification shall only be used onthose plastic materials deemed suitable by the manufacturer.1.3 Specialty threads or threads not requiring a leak-tightjoint are not covered in this specification.NOTE 1The terms “wrench makeup” an
4、d “wrench tight” are standardterminology for tightness and do not imply using a pipe wrench or othertools which would damage plastic pipe and fittings. The terms “hand-tight” and “hand-tight engagement” refer only to thread gaging (not pipeand fitting connections) and is the definition of the L1gage
5、 length.1.4 Thread DesignationsThe type of pipe threads in-cluded in this specification are designated by specifying insequence the nominal pipe size, number of threads per inch,and the thread series symbols as follows in accordance withANSI/ASME B 1.20.1:38-18 NPT. For left-hand threads addLH to th
6、e end of the designation, otherwise right-hand threadswill be understood. For example:38-18 NPT-LH.1.4.1 Each of these letters in the symbol has a definitesignificance as follows:N = National (American Standard)P = PipeT = Taper1.5 The values stated in inch-pound units are to be regardedas the stand
7、ard. No other units of measurement are included inthis standard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the appli
8、ca-bility of regulatory limitations prior to use. For specificprecautionary statements, see 7.2.1 and 8.3.2. Referenced Documents2.1 ASTM Standards:2D 1600 Terminology for Abbreviated Terms Relating toPlasticsE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsF 412 Terminology
9、 Relating to Plastic Piping Systems2.2 ASME Standards:3B 1.20.1 Pipe Threads, General Purpose (inch)B 1.7 Nomenclature, Definitions and Letter Symbols forScrew Threads3B 47.1 Gage Blanks3. Terminology3.1 Terminology is in accordance with Terminology F 412and abbreviations are in accordance with Term
10、inology D 1600,unless otherwise indicated.3.2 Nomenclature, definitions, and letter symbols for screwthreads are in accordance with ASME/ANSI B 1.7.4. American National Standard Taper Pipe Thread Form4.1 Thread FormThe form of thread profile specified inthis specification shall be known as the Ameri
11、can NationalStandard Taper Pipe Thread Form. The relations as specifiedherein, for form of thread and general notations are shown inFig. 1.4.2 Angle of ThreadThe angle between the sides of thethread is 60 when measured in an axial plane. The linebisecting this angle is perpendicular to the axis.4.3
12、Truncation and Thread HeightThe height of the sharpV thread, H, is as follows:H 5 0.866025p 5 0.866025/n (1)1This specification is under the jurisdiction of ASTM Committee F17 on PlasticPiping Systems and is the direct responsibility of Subcommittee F17.10 on Fittings.Current edition approved April
13、15, 2008. Published May 2008. Originallyapproved in 1994. Last previous edition approved in 2000 as F 1498 00e1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the
14、standards Document Summary page onthe ASTM website.3Available from American Society of Mechanical Engineers (ASME), ASMEInternational Headquarters, Three Park Ave., New York, NY 10016-5990, http:/www.asme.org.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM Internati
15、onal, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.where:p = pitch of thread, andn = threads per inch.4.3.1 The basic maximum height of the truncated thread, h(see Fig. 1) is based on factors entering into the manufacture ofcutting tools and the making of tight
16、 joints.h 5 0.800p 5 0.800/n (2)The crest and root of pipe threads are truncated a minimumof 0.033p. Maximum truncation for the crest and root of thesepipe threads is in Table 1. The crests and roots of the externaland internal threads may be truncated either parallel to theH = 0.866025p = height of
17、 60 sharp V thread b = 1 47 min. = thread taper angle for 1/16 taperh = 0.800000p = height of thread on product fc= depth of truncation at crestp =1/n = pitch (measured parallel to axis) fr= depth of truncation at rootn = number of threads per inch Fc= width of flat at cresta = 30 = thread flank ang
18、le Fr= width of flat at rootNOTE 1For a symmetrical straight screw thread, H = cot a/2n. For a symmetrical taper screw thread, H = (cot a tan2b tan a)/2n, so that the exactvalue for an American National Standard Taper Pipe Thread is H = 0.865743p as against H = 0.866025p, the value given above. For
19、an 8-pitch thread,which is the coarsest standard taper pipe thread pitch, the corresponding values of H are 0.108218 and 0.108253 respectively, the difference being0.000035 in. This difference being too small to be significant, the value of H = 0.866025p continues in use for threads of 0.750 in., or
20、 less, taper/ft onthe diameter.FIG. 1 Basic Form of American National Standard Taper Pipe ThreadF 1498 082pitch line or parallel to the axis.The sketches inTables 2-6 givea sectional view of this standard thread form, which representsthe truncated thread form by a straight line. However, whenclosely
21、 examined, the crests and roots of molded pipe threadsappear slightly rounded.4.4 Thread StartsMachinedFeathered starts are pro-duced by a 45 chamfer on the first thread when the thread iscut with a tap or die. The depth of chamfer shall be from34 to114 thread deep (see Fig. 2(a). Feathered starts a
22、re prone tocrossing and mutilation and shall not be molded.4.5 Thread StartsMoldedInternal and external moldedthreads shall begin with a taper or blunt start. A pilot shall beprovided from the face of the fitting and at the entering end ofthe external threads; it shall have a length to the start (fl
23、ank) ofthe first thread, equal to12 to34 the width of the thread pitch,1to114 thread pitch to the centerline. (Thread pitch equals oneturn; see Fig. 2(b) and Fig. 2(c).) The pilot shall be included inthe measurement of the thread length.4.5.1 Taper starts on the first thread are formed by the thread
24、rising from the minimum to maximum diameter while main-taining the 60 thread profile (see Fig. 2(b). The length of riseshall not exceed18 turn (45).4.5.2 Blunt starts on the first thread are formed by the threadrising from the minimum to maximum diameter while main-taining the 60 thread profile (see
25、 Fig. 2(c). The length of riseshall not be greater than twice the thread height. The blunt startis the preferred thread start.4.6 Plastic ThreadsGeneralThe minimum wall thick-ness (see Table 2) for the threaded portion of a plastic pipe orfitting depends upon the material and the application. ForTAB
26、LE 1 Limits on Crest and Root Truncation of American National Standard External and Internal Taper Pipe Threads, NPTAThreads/in.(n)Height ofSharp VThread (H)Height of Thread(h)Truncation (f) Equivalent Width of Flat (F)Min Max Tolerance Min Max ToleranceMax Min Formula Inch Formula Inch Formula Inch
27、 Formula Inch12345678910112131427 0.03208 0.02963 0.02496 0.033p 0.0012 0.096p 0.0036 0.0024 0.038p 0.0014 0.111p 0.0041 0.002718 0.04811 0.04444 0.03833 0.033p 0.0018 0.088p 0.0049 0.0031 0.038p 0.0021 0.102p 0.0057 0.003614 0.06186 0.05714 0.05071 0.033p 0.0024 0.078p 0.0056 0.0032 0.038p 0.0027 0
28、.090p 0.0064 0.003711.5 0.07531 0.06957 0.06261 0.033p 0.0029 0.073p 0.0063 0.0034 0.038p 0.0033 0.084p 0.0073 0.00408 0.10825 0.10000 0.09275 0.033p 0.0041 0.062p 0.0078 0.0037 0.038p 0.0048 0.072p 0.0090 0.0042AThe basic dimensions of the American National Standard Taper Pipe Thread are given in i
29、nches to four and five decimal places. While this implies a greater degreeof precision than is ordinarily attained, these dimensions are so expressed for the purpose of eliminating errors in computations.TABLE 2 ABS, CPVC, and PVC Reference InformationNominal PipeSize, in.Minimum Wall-Thickness, in.
30、 Minimum Hub-Diameter, in.Schedule 80PipeDWV Schedule 40and DWVSchedule 8018 0.095 . . . 0.526 0.64514 0.119 . . . 0.672 0.84038 0.126 . . . 0.821 1.00012 0.147 . . . 0.998 1.28034 0.154 . . . 1.221 1.4501 0.179 . . . 1.504 1.810114 0.191 0.100 1.871 2.200112 0.200 0.088 2.127 2.4502 0.218 0.066 2.6
31、34 3.000212 0.276 . . . 3.170 3.5603 0.300 0.086 3.841 4.250312 0.318 . . . 4.374 . . .4 0.337 0.104 4.907 5.3505 0.375 . . . 6.039 . . .6 0.432 . . . 7.203 7.6258 0.500 . . . 9.320 . . .10 0.593 . . . 11.614 . . .12 0.687 . . . 13.786 . . .F 1498 083pressure rated pipe, reduce the pressure rating f
32、or threaded pipeby one-half (50 %) that of unthreaded pipe. Some pressurerated pipe materials (for example, PP and PE) are not recom-mended for threaded applications. If the wall thickness is notspecified in a pipe or fitting standard, the manufacturer mustdetermine the appropriate wall thickness.4.
33、7 SealingWhere pressure-tight or leak-tight non-pressure joints are required, it is intended that taper pipethreads conforming to this specification be made up with PTFE(polytetrafluoroethylene or equivalent) tape or a chemicallycompatible a sealant-lubricant. Conventional pipe-thread com-pounds, pu
34、tty, linseed oil-base products, and unknown mix-tures shall not be used.NOTE 2Some TFE-fluorocarbon-paste compounds, even though theyare recommended by the manufacturer, may not be compatible with someplastics.4.8 Thread TightnessWrench MakeupSome lubricants(PTFE pastes, silicones, etc.) will provid
35、e added lubricity,which can result in more finger-tight engagement than withsealants. The maximum recommended tightness is two turnspast finger tight for both internal and external threads. Overtightening of interal threads will produce hoop stresses greaterthan plastic can withstand, resulting in s
36、plit fittings.NOTE 3When assembling metal and plastic threads, the preferredmethod is plastic external threads to metal internal threads. Cyclic heatingand cooling may result in dripping leaks.NOTE 4When PTFE tape is used to seal the threads, wrap the externalthreads with 2 to 3 layers.TABLE 3 Basic
37、 Dimensions of American National Standard Taper Thread, NPTANOTE 1Wrench makeup modified for plastic.NominalPipe Size,in.OutsideDiameter ofPipe (D)Threads/in.(n)Pitch of Thread(P)Pitch Diameter atBeginning of Ex-ternal Thread (E0)Hand-tight Gage Engagement Effective Thread, ExternalLengthB(L1)Diamet
38、erC(E1)LengthD(L2)Diameter(E2)Inch Threads Inch Threads123 4 5 6789101116 0.3125 27 0.03704 0.27118 0.160 4.32 0.28118 0.2611 7.05 0.2875018 0.405 27 0.03704 0.36351 0.1615 4.36 0.37360 0.2639 7.12 0.3800014 0.540 18 0.05556 0.47739 0.2278 4.10 0.49163 0.4018 7.23 0.5025038 0.675 18 0.05556 0.61201
39、0.240 4.32 0.62701 0.4078 7.34 0.6375012 0.840 14 0.07143 0.75843 0.320 4.48 0.77843 0.5337 7.47 0.7917934 1.050 14 0.07143 0.96768 0.339 4.75 0.98887 0.5457 7.64 1.001791 1.315 11.5 0.08696 1.21363 0.400 4.60 1.23863 0.6828 7.85 1.25630114 1.660 11.5 0.08696 1.55713 0.420 4.83 1.58338 0.7068 8.13 1
40、.60130112 1.900 11.5 0.08696 1.79609 0.420 4.83 1.82234 0.7235 8.32 1.841302 2.375 11.5 0.08696 2.26902 0.436 5.01 2.29627 0.7565 8.70 2.31630212 2.875 8 0.12500 2.71953 0.682 5.46 2.76216 1.1375 9.10 2.790623 3.500 8 0.12500 3.34062 0.766 6.13 3.38850 1.2000 9.60 3.41562312 4.000 8 0.12500 3.83750
41、0.821 6.57 3.88881 1.2500 10.00 3.915624 4.500 8 0.12500 4.33438 0.844 6.75 4.38712 1.3000 10.40 4.415625 5.563 8 0.12500 5.39073 0.937 7.50 5.44929 1.4063 11.25 5.478626 6.625 8 0.12500 6.44609 0.958 7.66 6.50597 1.5125 12.10 6.540628 8.625 8 0.12500 8.43359 1.063 8.50 8.50003 1.7125 13.70 8.540621
42、0 10.750 8 0.12500 10.54531 1.210 9.68 10.62094 1.9250 15.40 10.6656212 12.750 8 0.12500 12.53281 1.360 10.88 12.61781 2.1250 17.00 12.66562AThe basic dimensions of the American National Standard Taper Pipe Thread are given in inches to four or five decimal places. While this implies a greater degre
43、e ofprecision than is ordinarily attained, these dimensions are the basis of gage dimensions and are so expressed for the purpose of eliminating errors in computations.BAlso length of thin ring gage and length from gaging notch to small end of plug gage.CAlso pitch diameter at gaging notch (hand-tig
44、ht plane).DAlso length of plug gage.F 1498 0844.9 InspectionA gaging method of tolerances is pre-scribed in this specification to effect a functional inspection ofthe hand-tight L1engagement threads. However, conformanceto this specification requires that all basic design dimensions bemet (within ap
45、plicable tolerances) including extension of thethread elements (L2 L1) to provide for wrench-tight makeup.Therefore, additional methods of gaging may be employed toevaluate conformance to the basic design dimensions. Whenadditional methods of gaging are employed, they shall beagreed upon between the
46、 supplier and the purchaser. Because itis known that injection molded threads that are removed fromthe mold before they are completely cooled will distort in formso that they will not gage properly, threads suspected of beingso distorted should be inspected with an optical comparator todetermine the
47、ir true quality.5. Specification for General Purpose Taper Pipe Threads,NPT5.1 Taper Pipe ThreadsThreads made in accordance withthese specifications consist of an external taper and an internaltaper thread, to form a normal type of joint having generalapplication on pipe and fittings (see Fig. 3). T
48、he NPT taperpipe threads are intended to be made up wrench-tight (maxi-mum two turns past finger-tight), and with a lubricant orsealant whenever a pressure-tight or leak-tight non-pressurejoint is required (see 4.7 and 4.8). Sealing is affected byout-of-roundness which is possible between the wrench
49、-tightmated parts in final assembly. This will vary depending on themethod for producing the thread in conjunction with theelasticity or ductility, or both, of the mating parts and theresultant conformance at final assembly.5.1.1 Thread Designation and NotationAmerican Na-tional Standard Taper Pipe Threads are designated in accor-dance with 3.2 as follows:38-18 NPT.5.1.1.1 Standard notation applicable to American NationalStandard Taper Pipe Threads is shown in Fig. 4.5.1.2 Form of Thread:5.1.2.1 The basic dimension
