Thread data

NPSM thread chart and dimensions

American straight pipe thread with the NPT pitch but no taper. It seals with a washer, O ring or 30° seat instead of the thread, and is used on hose swivels, pipe unions and some hydraulic couplings.

Standard: ASME B1.20.1 NPSM straight pipe
Seals by: 30° swivel seat, gasket or O ring
Used for: Swivel hose ends, pumps and mechanical pipe joints
Sizes: 1/8 to 2

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NPSM dimensions

The dimensions we machine to. Pressure values are nominal working ratings for steel at room temperature.

Size	Male	Female	Threads per inch	Major dia, male	Pitch dia	Minor dia, male	Minor dia, female	Male thread length	Seal	Rated to
1/8	1/8-27 NPSM	1/8-27 NPSM	27	10.12 mm	9.51 mm	8.96 mm	9.10 mm	6.60 mm	30° swivel seat, gasket or O ring	3,000 psi
1/4	1/4-18 NPSM	1/4-18 NPSM	18	13.43 mm	12.51 mm	11.70 mm	11.90 mm	10.16 mm	30° swivel seat, gasket or O ring	3,000 psi
3/8	3/8-18 NPSM	3/8-18 NPSM	18	16.86 mm	15.94 mm	15.12 mm	15.33 mm	10.41 mm	30° swivel seat, gasket or O ring	2,500 psi
1/2	1/2-14 NPSM	1/2-14 NPSM	14	20.95 mm	19.77 mm	18.72 mm	18.99 mm	13.46 mm	30° swivel seat, gasket or O ring	2,500 psi
3/4	3/4-14 NPSM	3/4-14 NPSM	14	26.30 mm	25.12 mm	24.07 mm	24.33 mm	13.97 mm	30° swivel seat, gasket or O ring	2,000 psi
1	1-11.5 NPSM	1-11.5 NPSM	11.5	32.90 mm	31.46 mm	30.19 mm	30.50 mm	17.27 mm	30° swivel seat, gasket or O ring	1,500 psi
1 1/4	1 1/4-11.5 NPSM	1 1/4-11.5 NPSM	11.5	41.65 mm	40.22 mm	38.94 mm	39.26 mm	18.03 mm	30° swivel seat, gasket or O ring	1,250 psi
1 1/2	1 1/2-11.5 NPSM	1 1/2-11.5 NPSM	11.5	47.72 mm	46.29 mm	45.01 mm	45.33 mm	18.29 mm	30° swivel seat, gasket or O ring	1,000 psi
2	2-11.5 NPSM	2-11.5 NPSM	11.5	59.76 mm	58.33 mm	57.05 mm	57.37 mm	19.30 mm	30° swivel seat, gasket or O ring	750 psi

Adapters with NPSM

NPSM to NPT adapters

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