The NPSM (NATIONAL PIPE STRAIGHT MECHANICAL) Female Pipe Swivel was designed to eliminate hose stress from twisting during assembly
and reduce the number of different hose fittings required. The NPSM femal pipe swivel seats on a 30°seat (chamfer) and is visiable down inside of the swivel nut.
This swivel nut is permanently attached to the body and mates with a male pipe thread that has a 30°seat (chamfer) machined into the end of it. The threads bring both
30°seats (flare and chamfer) together creating a metal-to-metal seal.
It should be noted that not all NPT and NPTF male pipe threads have this 30° chamfer. It is optional according to SAE standards under J514. The 30° seat is a chamfer
machined into the inside diameter of a male pipe thread and should not be confused with a relatively small deburr chamfer.
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NPSM Thread Dimensions |
Size (inches) |
Threads Per Inch |
Outside Dia. of the Male (max) |
Inside Dia. of the Female (min) |
02 (1/8) |
27 |
0.397 |
0.358 |
04 (1/4) |
18 |
0.526 |
0.468 |
06 (3/8) |
18 |
0.662 |
0.603 |
08 (1/2) |
14 |
0.823 |
0.747 |
12 (3/4) |
14 |
1.034 |
0.958 |
16 (1) |
11.5 |
1.293 |
1.201 |
20 (1¼) |
11.5 |
1.638 |
1.546 |
24 (1½) |
11.5 |
1.877 |
1.785 |
32 (2) |
11.5 |
2.351 |
2.259 |
40 (2½) |
8 |
2.841 |
2.708 |
48 (3) |
8 |
3.467 |
3.334 |
64 (4) |
8 |
4.466 |
4.333 |
80 (5) |
8 |
5.528 |
5.395 |
96 (6) |
8 |
6.585 |
6.452 |
Thread Size = Male Thread OD - Threads per Inch
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