Editing National pipe thread (section)

== Standard sizes ==
{| class="wikitable"  style="text-align:center"
|+ American Society of Mechanical Engineers National Pipe Thread Taper (NPT)<ref>[http://www.engineeringtoolbox.com/npt-national-pipe-taper-threads-d_750.html Engineering toolbox]</ref>
|-
!           rowspan="2" | [[Nominal size|Nominal]] <br />pipe size
!           rowspan="2" | [[Screw thread#Lead, pitch, and starts|Thread <br />density]]
! colspan=2 rowspan="2" | [[Lead (engineering)|Thread pitch P]]
! colspan=3             | Hand-tight engagement<ref name="piping-designer">{{Cite web|url=http://www.piping-designer.com/index.php/disciplines/mechanical/84-stationary-equipment/fastener/1156-national-pipe-thread?title=National_Pipe_Thread|title = National Pipe Thread}}</ref>
! colspan=3             | Effective thread<ref name="piping-designer" />
!           rowspan="2" | Overall <br />length L<sub>4</sub><ref name="piping-designer" />
! colspan=2 rowspan="2" | [[Real versus nominal value#Engineering|Actual]] outside <br />diameter D
! colspan=2 rowspan="2" | [[List of drill and tap sizes|Tap drill]]
|-
! Length L<sub>1</sub>
! Turns
! Diameter E<sub>1</sub>
! Length L<sub>2</sub>
! Turns
! Diameter E<sub>2</sub>
|-
! inch
! inch{{sup|−1}}
! inch !! mm
! inch
! 
! inch
! inch
! 
! inch
! inch
! inch !! mm
! inch !! mm
|-
| {{frac|1|16}}
| 27
| {{convert|0.03703704|in|mm|4|disp=table}}
| 0.1600 || 4.32 || 0.28118
| 0.2611 || 7.05 || 0.2875

| 0.3896
| {{convert|0.313|in|mm|3|disp=table}}
| ||
|-
| {{frac|1|8}} || 27
| {{convert|0.03703704|in|mm|4|disp=table}}
| 0.1615 || 4.36 || 0.37360
| 0.2639 || 7.13 || 0.38000
| 0.3924
| {{convert|0.405|in|mm|3|disp=table}}
| {{convert|0.339|in|mm|4|disp=table}}
|-
| {{frac|1|4}}
| 18
| {{convert|0.05555555|in|mm|4|disp=table}}
| 0.2278 || 4.10 || 0.49163
| 0.4018 || 7.23 || 0.50250
| 0.5946
| {{convert|0.540|in|mm|3|disp=table}}
| {{convert|7/16|in|mm|3|disp=table}}
|-
| {{frac|3|8}}
| 18
| {{convert|0.05555555|in|mm|4|disp=table}}
| 0.2400 || 4.32 || 0.62701
| 0.4078 || 7.34 || 0.63750
| 0.6006
| {{convert|0.675|in|mm|3|disp=table}}
| {{convert|37/64|in|mm|3|disp=table}}
|-
| {{frac|1|2}}
| 14
| {{convert|0.07142857|in|mm|4|disp=table}}
| 0.3200 || 4.48 || 0.77843
| 0.5337 || 7.47 || 0.79178
| 0.7815
| {{convert|0.840|in|mm|4|disp=table}}
| {{convert|23/32|in|mm|4|disp=table}}
|-
| {{frac|3|4}}
| 14
| {{convert|0.07142857|in|mm|4|disp=table}}
| 0.3390 || 4.75 || 0.98887
| 0.5457 || 7.64 || 1.00178
| 0.7935
| {{convert|1.050|in|mm|4|disp=table}}
| {{convert|59/64|in|mm|4|disp=table}}
|-
| 1
| {{frac|11|1|2}}
| {{convert|0.08695652|in|mm|4|disp=table}}
| 0.4000 || 4.60 || 1.23863
| 0.6828 || 7.85 || 1.25631
| 0.9845
| {{convert|1.315|in|mm|4|disp=table}}
| {{convert|1+5/32|in|mm|4|disp=table}}
|-
| {{frac|1|1|4}}
| {{frac|11|1|2}}
| {{convert|0.08695652|in|mm|4|disp=table}}
| 0.4200 || 4.83 || 1.58338
| 0.7068 || 8.13 || 1.60131
| 1.0085
| {{convert|1.660|in|mm|4|disp=table}}
| {{convert|1+1/2|in|mm|4|disp=table}}
|-
| {{frac|1|1|2}}
| {{frac|11|1|2}}
| {{convert|0.08695652|in|mm|4|disp=table}}
| 0.4200 || 4.83 || 1.82234
| 0.7235 || 8.32 || 1.84131
| 1.0252
| {{convert|1.900|in|mm|4|disp=table}}
| {{convert|1+47/64|in|mm|4|disp=table}}
|-
| 2
| {{frac|11|1|2}}
| {{convert|0.08695652|in|mm|4|disp=table}}
| 0.4360 || 5.01 || 2.29627
| 0.7565 || 8.70 || 2.31630
| 1.0582
| {{convert|2.375|in|mm|4|disp=table}}
| {{convert|2+7/32|in|mm|4|disp=table}}
|-
| {{frac|2|1|2}}
| 8
| {{convert|0.12500000|in|mm|4|disp=table}}
| 0.6820 || 5.46 || 2.76216
| 1.1375 || 9.10 || 2.79063
| 1.5712
| {{convert|2.875|in|mm|4|disp=table}}
| {{convert|2+5/8|in|mm|4|disp=table}}
|-
| 3
| 8
| {{convert|0.12500000|in|mm|4|disp=table}}
| 0.7660 || 6.13 || 3.38850
| 1.2000 || 9.60 || 3.41563
| 1.6337
| {{convert|3.500|in|mm|4|disp=table}}
| {{convert|3+1/4|in|mm|4|disp=table}}
|-
| {{frac|3|1|2}}
| 8
| {{convert|0.12500000|in|mm|4|disp=table}}
| 0.8210 || 6.57 || 3.88881
| 1.2500 || 10.00 || 3.91563
| 1.6837
| {{convert|4.000|in|mm|4|disp=table}}
| {{convert|3+3/4|in|mm|4|disp=table}}
|-
| 4
| 8
| {{convert|0.12500000|in|mm|4|disp=table}}
| 0.8440 || 6.75 || 4.38713
| 1.3000 || 10.40 || 4.41563
| 1.7337
| {{convert|4.500|in|mm|4|disp=table}}
| {{convert|4+1/4|in|mm|4|disp=table}}
|-
| {{frac|4|1|2}}
| 8
| {{convert|0.12500000|in|mm|4|disp=table}}
| || || 
| || || 
| 
| {{convert|5.000|in|mm|4|disp=table}}
| {{convert|4+3/4|in|mm|4|disp=table}}
|-
| 5
| 8
| {{convert|0.12500000|in|mm|4|disp=table}}
| 0.9370 || 7.50 || 5.44929
| 1.4063 || 11.25 || 5.47863
| 1.8400
| {{convert|5.563|in|mm|4|disp=table}}
| {{convert|5+9/32|in|mm|4|disp=table}}
|-
| 6
| 8
| {{convert|0.12500000|in|mm|4|disp=table}}
| 0.9580 || 7.66 || 6.50597
| 1.5125 || 12.10 || 6.54063
| 1.9462
| {{convert|6.625|in|mm|4|disp=table}}
| {{convert|6+11/32|in|mm|4|disp=table}}
|-
| 8
| 8
| {{convert|0.12500000|in|mm|4|disp=table}}
| 1.0630 || 8.50 || 8.50003
| 1.7125 || 13.70 || 8.54063
| 2.1462
| {{convert|8.625|in|mm|4|disp=table}}
| ||
|-
| 10
| 8
| {{convert|0.12500000|in|mm|4|disp=table}}
| 1.2100 || 9.68 || 10.62094
| 1.9250 || 15.40 || 10.66563
| 2.3587
| {{convert|10.750|in|mm|4|disp=table}}
| ||
|-
| 12
| 8
| {{convert|0.12500000|in|mm|4|disp=table}}
| 1.3600 || 10.88 || 12.61781
| 2.1250 || 17.00 || 12.66563
| 2.5587
| {{convert|12.750|in|mm|4|disp=table}}
| ||
|-
| 14
| 8
| {{convert|0.12500000|in|mm|4|disp=table}}
| 1.5620 || 12.50 || 13.87263
| 2.2500 || 18.00 || 13.91563
| 2.6837
| {{convert|14.000|in|mm|4|disp=table}}
| ||
|-
| 16
| 8
| {{convert|0.12500000|in|mm|4|disp=table}}
| 1.8120 || 14.50 || 15.87575
| 2.4500 || 19.60 || 15.91563
| 2.8837
| {{convert|16.000|in|mm|4|disp=table}}
| ||
|-
| 18
| 8
| {{convert|0.12500000|in|mm|4|disp=table}}
| 2.0000 || 16.00 || 17.87500
| 2.6500 || 21.20 || 17.91563
| 3.0837
| {{convert|18.000|in|mm|4|disp=table}}
| ||
|-
| 20
| 8
| {{convert|0.12500000|in|mm|4|disp=table}}
| 2.1250 || 17.00 || 19.87031
| 2.8500 || 22.80 || 19.91563
| 3.2837
| {{convert|20.000|in|mm|4|disp=table}}
| ||
|-
| 24
| 8
| {{convert|0.12500000|in|mm|4|disp=table}}
| 2.3750 || 19.00 || 23.86094
| 3.2500 || 26.00 || 23.91563
| 3.6837
| {{convert|24.000|in|mm|4|disp=table}}
| ||
|}
[[File:NPT_Dimensions.svg|frame|center|alt=A NPT dimensions|Hand-tight and effective thread engagement lengths]]