Pipe threads are also male and female.
Be sure to specify the gender required for
your specific fitting. A barbed hose adapter
to fit a^3 / 4 - inch hose to a^3 / 4 - inch NPS male
pipe fitting, suited to fuel systems, would be
specified as a “female^3 / 4 - inch NPTF pipe to(^3) /
4 - inch hose connector.”
If you need to determine the size of
U.S. pipe thread, measure either dimension
A for male fittings or B for female fittings
(Figure A-B-1). Enter that in the chart, and
read the NPS pipe size. Note the threads
per inch (TPI). This changes with the size
of pipe. TPI must be matched exactly or the
fitting won’t work.
Hose-to-Pipe Size Considerations
While pipe is dimensioned by the preceding
various series of standards (and according to
the tables that follow), hose is dimensioned
by inside diameter, ID. Thus if you were spec-
ifying hose for a tank fill to mate with a stan-
dard 1^1 / 2 - inch fill pipe, the OD of the pipe
would be 1. 90 inches and you would use
2-inch ID hose or specify hose to mate with
11 / 2 - inch IPS (48. 3 3 .7) pipe. (See Table B-4.)
In smaller sizes, hose must fit over
barbed connectors (see Figure A-B-2). These
connectors must be carefully selected to
match the pipe and hose.International Pipe Standards and Pipe-Size Tables
Figure A-B-2.
Hose connectors
(Courtesy Amazon
Hose & Rubber Co.)TABLE B-3. U.S. PIPE-THREAD TABLE
OD NPS or Engagement Threads
inches IPS Pipe for Tight per
“A” or “B” Size, in. Joint “C,” in. inch
0.3125^1 ⁄ 16 0.2611 27
0.4050^1 ⁄ 8 0.2639 27
0.5400^1 ⁄ 4 0.4018 18
0.6750^3 ⁄ 8 0.4078 18
0.8400^1 ⁄ 2 0.5337 14
1.0500^3 ⁄ 4 0.5457 14
1.3150 1 0.6828 11.5
1.6600 11 ⁄ 4 0.7068 11.5
1.9000 11 ⁄ 2 0.7235 11.5
2.3750 2 0.7565 11.5
2.8750 21 ⁄ 2 1.1375 8
3.5000 3 1.2000 8
4.0000 31 ⁄ 2 1.2500 8
4.5000 4 1.3000 8Use with Figure A-B-1.