Description of productsTechnical Information 17. Bar diameter for external threads (for cutting type dies) ■For American taper pipe threads (NPT) Unit:mm ■For American Dryseal taper pipe threads (NPTF) Unit:mm Bar diameter Outside diameter Bar diameter Outside diameter Size of pipe Size of pipe Taper (tip diameter) Straight (for reference) Taper (tip diameter) Straight (for reference) 1/16-27 NPT 7.64 7.93 7.938 1/16-27 NPTF 7.61 7.93 7.938 1/8-27 NPT 9.98 10.28 10.287 1/8-27 NPTF 9.95 10.28 10.287 1/4-18 NPT 13.25 13.71 13.716 1/4-18 NPTF 13.20 13.71 13.716 3/8-18 NPT 16.67 17.14 17.145 3/8-18 NPTF 16.63 17.14 17.145 1/2-14 NPT 20.7 21.3 21.336 1/2-14 NPTF 20.7 21.3 21.336 3/4-14 NPT 26.0 26.6 26.670 3/4-14 NPTF 26.0 26.6 26.670 1 -11 NPT 32.5 33.3 33.401 1 -11 NPTF 32.5 33.4 33.401 1 1/4-11 1/2 NPT 41.3 42.1 42.164 1 1/4-11 1/2 NPTF 41.3 42.1 42.164 ■For American parallel pipe threads (NPSM) Unit:mm Outside diameter of external thread Outside diameter Size Bar diameter of pipe Max. Min. (for reference) 1/16-27 NPSM 7.721 7.544 7.59 7.938 1/8-27 NPSM 10.083 9.906 9.95 10.287 1/4-18 NPSM 13.360 13.132 13.19 13.716 3/8-18 NPSM 16.814 16.587 16.64 17.145 1/2-14 NPSM 20.904 20.651 20.7 21.336 3/4-14 NPSM 26.263 26.010 26.1 26.670 1 -11 1/2 NPSM 32.842 32.538 32.6 33.401 1 1/4-11 1/2 NPSM 41.605 41.301 41.4 42.164 Technical-56