1、Designation: F1498 08 (Reapproved 2012)1An American National StandardStandard Specification forTaper Pipe Threads 60 for Thermoplastic Pipe and Fittings1This standard is issued under the fixed designation F1498; the number immediately following the designation indicates the year oforiginal adoption
2、or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This specification establishes requirements for dimen-sions and gaging of ta
3、per pipe threads 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 “w
4、rench makeup” and “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 definiti
5、on of the L1gage length.1.4 Thread DesignationsThe type of pipe threads includedin this specification are designated by specifying in sequencethe nominal pipe size, number of threads per inch, and thethread series symbols as follows in accordance with ANSI/ASME B 1.20.1:38-18 NPT. For left-hand thre
6、ads add LH tothe end of the designation, otherwise right-hand threads will beunderstood. 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 regar
7、dedas the standard. 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 dete
8、rmine the applica-bility of regulatory limitations prior to use. For specificprecautionary statements, see 7.2.1 and 8.3.2. Referenced Documents2.1 ASTM Standards:2D1600 Terminology forAbbreviated Terms Relating to Plas-ticsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsF41
9、2 Terminology 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 F412and abbreviations are in accordan
10、ce with Terminology D1600,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 a
11、s the American 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 th
12、e axis.4.3 Truncation and Thread HeightThe height of the sharpV thread, H, is as follows:H 5 0.866025p 5 0.866025/n (1)where:p = pitch of thread, andn = threads per inch.1This specification is under the jurisdiction of ASTM Committee F17 on PlasticPiping Systems and is the direct responsibility of S
13、ubcommittee F17.10 on Fittings.Current edition approved Sept. 15, 2012. Published November 2012. Originallyapproved in 1994. Last previous edition approved in 2008 as F1498 08. DOI:10.1520/F1498-08R12E01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Se
14、rvice at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the 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
15、.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.3.1 The basic maximum height of the truncated thread, h(see Fig. 1) is based on factors entering into the manufacture
16、ofcutting tools and the making of tight 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 p
17、arallel to theH = 0.866025p = height of 60 sharp V thread b = 1 47 min. = thread taper angle for116 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 f
18、lat at cresta = 30 = thread flank angle Fr= width of flat at rootNOTE 1For a symmetrical straight screw thread, H = cot /2n. For a symmetrical taper screw thread, H = (cot tan2 tan )/2n, so that the exactvalue for an American National Standard Taper Pipe Thread is H = 0.865743p as against H = 0.8660
19、25p, the value given above. For 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
20、use for threads of 0.750 in., or less, taper/ft onthe diameter.FIG. 1 Basic Form of American National Standard Taper Pipe ThreadF1498 08 (2012)12pitch line or parallel to the axis.The sketches in Tables 2-6 givea sectional view of this standard thread form, which representsthe truncated thread form
21、by a straight line. However, whenclosely 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
22、 deep (see Fig. 2(a). Feathered starts are 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;
23、 it shall have a length to the start (flank) 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 t
24、he first thread are formed by the threadrising 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
25、 main-taining the 60 thread profile (see 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 orTABLE 1 Limits on Cre
26、st 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 Formula Inch12345
27、678910112131427 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 0.090p 0.0064 0.003
28、711.5 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 inches to four and
29、five decimal places. While this implies a greater degree ofprecision 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. Minimum Hub-Diame
30、ter, 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 2.634 3.000212 0.276
31、. . . 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 . . .F1498 08 (2012)13fitting depends upon the material and the application. Forpr
32、essure rated pipe, reduce the pressure rating for 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
33、mustdetermine the appropriate wall thickness.4.7 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-lub
34、ricant. Conventional pipe-threadcompounds, putty, linseed oil-base products, and unknownmixtures 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 lubricant
35、s(PTFE pastes, silicones, etc.) will provide 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 internal threads will produce hoop stresses great
36、erthan plastic can withstand, resulting in split fittings.NOTE 3When assembling metal and plastic threads, the preferredmethod is plastic external (male) threads to metal internal (female)threads. Cyclic heating and cooling may result in dripping leaks.NOTE 4When PTFE tape is used to seal the thread
37、s, wrap the externalthreads with 2 to 3 layers.TABLE 3 Basic 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
38、 Gage Engagement Effective Thread, ExternalLengthB(L1)DiameterC(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
39、4.10 0.49163 0.4018 7.23 0.5025038 0.675 18 0.05556 0.61201 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
40、 1.660 11.5 0.08696 1.55713 0.420 4.83 1.58338 0.7068 8.13 1.60130112 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
41、6.13 3.38850 1.2000 9.60 3.41562312 4.000 8 0.12500 3.83750 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 8.62
42、5 8 0.12500 8.43359 1.063 8.50 8.50003 1.7125 13.70 8.5406210 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 fou
43、r or five decimal places. While this implies a greater degree 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
44、 of plug gage.CAlso pitch diameter at gaging notch (hand-tight plane).DAlso length of plug gage.F1498 08 (2012)144.9 InspectionAgaging method of tolerances is prescribedin this specification to effect a functional inspection of thehand-tight L1engagement threads. However, conformance tothis specific
45、ation requires that all basic design dimensions bemet (within applicable 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 meth
46、ods of gaging are employed, they shall beagreed upon between the 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 distorte
47、d should be inspected with an optical comparator todetermine their 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 join
48、t having generalapplication on pipe and fittings (see Fig. 3). The 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
49、affected byout-of-roundness which is possible between the wrench-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
