npt wikipedia.pdf

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Threaded pipe and elbow. The pipehas a male NPT thread, while theelbow's is female.

National pipe threadFrom Wikipedia, the free encyclopedia

National Pipe Thread Taper (NPT ) is a U. . standard for taperedthreads !sed on threaded pipes and fittin"s. #n contrast to strai"ht threadsthat are fo!nd on a bolt, a taper thread will p!ll ti"ht and therefore make a

fl!id$ti"ht seal. #n %merica, William ellers set the standard for n!ts, bolts, and screws which became the National Pipe Tapered Thread (NPT)

in & .*&+

Contents

◾ & Usa"e◾ pecifications

◾ .& Thread form◾ . NPTF

◾ - Table of standard si es◾ ee also◾ / 0eferences◾ F!rther readin"◾ 1 23ternal links

UsageThreaded pipes can pro4ide an effecti4e seal for pipes transportin" li5!ids, "ases, steam, and hydra!lic fl!id.

These threads are now !sed in materials other than steel and brass, incl!din" PTF2, * + P67, nylon, bron e, andcast iron.

The taper on NPT threads allows them to form a seal when tor5!ed as the flanks of the threads compress a"ainsteach other, as opposed to parallel8strai"ht thread fittin"s or compression fittin"s in which the threads merely holdthe pieces to"ether and do not pro4ide the seal. %s the thread body is tapered (9.1/ in8ft or ./ mm8m) a lar"erdiameter keeps compressin" into a smaller diameter and finally forms a seal (no clearance remains between thecrests and roots of the threads beca!se of the taper). This means that NPT fittin"s sho!ld be b!rr$free andl!bricated !sin" a l!bricatin" material like l!bricatin" paste or tape. The !se of tape also helps to limit corrosionon the threads, which otherwise can make f!t!re disassembly nearly impossible.

7ommonly !sed si es are & : , & : , - : , & : , - : , &, && : , && : , and inch, appearin" on pipes and fittin"s by most U. .

s!ppliers. i es smaller than & : inch are occasionally !sed for compressed air, while si es lar"er than inches are!ncommon, d!e to the !se of alternati4e methods of ;oinin" that are !sed with these lar"er si es.

Specifications

NPT is defined by %N #8% <2 standard =&. 9.&. *-+

Pipe threads are different from machine$screw and bolt threads. Those are desi"nated N7 (national coarse) and NF (national fine.) The bi""est difference is the taper on pipe threads.

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The taper rate for all NPT threads is 1 in 16 ( 3 ⁄ 4 inch per foot or 62.5 millimeters per meter) measured b thechan!e of diameter (of the pipe thread) o"er distance. The an!le bet#een the taper and the center a$is of the pipe

is tan %1(1 ⁄ 32) & 1.' * & 1* 4'+ 24,.

Nominal Pipe -i e (NP-) is loosel related to the inside diameter of -chedule 4/ pipe. 0ecause of the pipe #allthic ness the actual diameter of the threads is lar!er than the NP- considerabl so for small NP-. Pipe of other

schedules #ith a certain NP- has different #all thic ness but the same outside diameter and thread profile as-chedule 4/ so the inside diameter of the pipe is therefore different from the NP-.

Thread form

NPT and NP- threads ha"e a 6/* included an!le and ha"e a -ellers thread form (flattened pea s and "alle s).

NPTF

semi compatible "ariant called National Pipe Taper Fuel (NPTF ) also called Dryseal American NationalStandard Taper Pipe Thread defined b N- 01.2/.3 is desi!ned to pro"ide a more lea free seal #ithoutthe use of teflon tape or other sealant compound. NPT7 threads are the same basic shape but #ith crest and roothei!hts ad8usted for an interference fit eliminatin! the spiral lea a!e path.

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Table of standard sizes





NPT – American Standard Pipe Thread Taper >4?





14 8 0.125 in or3.1750 mm

14.000 in or355.6000 mm

16 8 0.125 in or3.1750 mm

16.000 in or406.4000 mm

18 8 0.125 in or3.1750 mm

18.000 in(457.2000 mm)

20 8 0.125 in or3.1750 mm

20.000 in(508.0000 mm)

24 8 0.125 in or3.1750 mm

24.000 in(609.6000 mm)

See also

◾ AN thread◾ British standard pipe thread◾ Fire hose thread◾ Garden hose thread

◾ an!er"e#inde◾ $hread an"%e◾ $hreaded pipe◾ Gender o& 'onne'tors and &asteners

References

1. ^ http ###.'o%der.'om orta%s 0 *i+rar, -eso r'es *iterat re /hite apers o' ments N $ #hitepaper.pd&

2. ^ http ###.mi'romo%d.'om threaded pipin".htm% $F threaded pipe and &ittin"s man &a't rer

3. ^ http ###.hem'o"a"es.'om ansi.htm

4. ^ n"ineerin" too%+o (http ###.en"ineerin"too%+o .'om npt nationa% pipe taper threads d 750.htm%)

Further reading

◾ +er" ri Fran %in . ones :o%+roo *. :orton :enr, :. -,&&e% (2000). ed. ;hristopher . <';a %e,

-i''ardo :ea%d and < hammed =>+a% : ssain ed. Machinery's Handbook (26th edition ed.). Ne# ?or

=nd stria% ress =n'. =@BN 0 8311 2635 3.

External links

◾ A@< B1.20. 1983 ipe $hreads Genera% rpose =n'h (http ###.asme.or" prod 'ts 'odes

standards pipe threads "enera% p rpose in'h)◾ 1 (http p +%i'aa.ansi.or" sites apd% o' ments @tandardsC20A'tion 2011C20 Fs @AD4220.pd&)◾ pipeandhose.'om (http pipeandhose.'om)◾ 2 (http ###.en"ineerin"too%+o .'om npt nationa% pipe taper threads d 750.htm%)

-etrieEed &rom http en.#i ipedia.or" # inde .php tit%eHNationa% pipe threadIo%didH623076999

;ate"ories <e'hani'a% standards ipin" % m+in" $hreadin" (man &a't rin")

◾ $his pa"e #as %ast modi&ied on 27 A " st 2014 at 19 45.

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#)gina * de * +ational pipe thread - $ikipedia the !ree encyclopedia

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