Thread data

BSPT thread chart and dimensions

British tapered pipe thread. It seals on the thread like NPT, but with a 55° thread form and a different pitch in most sizes, so the two are not interchangeable. Common on imported equipment and international pipework.

Standard: ISO 7-1
Seals by: Taper, sealant
Used for: International pipe
Sizes: 1/8 to 3

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BSPT dimensions

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

Size	Male	Female	Threads per inch	Pitch	Major dia	Pitch dia	Minor dia	Gauge length	Useful thread	Taper	Tap drill	Rated to
1/8	R1/8	Rc1/8	28	0.907 mm	9.73 mm	9.15 mm	8.57 mm	4.00 mm	6.50 mm	1:16 on diameter	8.4 mm	10,150 psi
1/4	R1/4	Rc1/4	19	1.337 mm	13.16 mm	12.30 mm	11.45 mm	6.00 mm	9.70 mm	1:16 on diameter	11.2 mm	7,975 psi
3/8	R3/8	Rc3/8	19	1.337 mm	16.66 mm	15.81 mm	14.95 mm	6.40 mm	10.10 mm	1:16 on diameter	14.75 mm	6,018 psi
1/2	R1/2	Rc1/2	14	1.814 mm	20.95 mm	19.79 mm	18.63 mm	8.20 mm	13.20 mm	1:16 on diameter	18.25 mm	6,018 psi
3/4	R3/4	Rc3/4	14	1.814 mm	26.44 mm	25.28 mm	24.12 mm	9.50 mm	14.50 mm	1:16 on diameter	23.75 mm	5,003 psi
1	R1	Rc1	11	2.309 mm	33.25 mm	31.77 mm	30.29 mm	10.40 mm	16.80 mm	1:16 on diameter	30 mm	5,003 psi
1 1/4	R1 1/4	Rc1 1/4	11	2.309 mm	41.91 mm	40.43 mm	38.95 mm	12.70 mm	19.10 mm	1:16 on diameter	38.5 mm	3,045 psi
1 1/2	R1 1/2	Rc1 1/2	11	2.309 mm	47.80 mm	46.32 mm	44.84 mm	12.70 mm	19.10 mm	1:16 on diameter	44.5 mm	3,045 psi
2	R2	Rc2	11	2.309 mm	59.61 mm	58.14 mm	56.66 mm	15.90 mm	23.40 mm	1:16 on diameter	56 mm	2,538 psi
2 1/2	R2 1/2	Rc2 1/2	11	2.309 mm	75.18 mm	73.71 mm	72.23 mm	17.50 mm	26.70 mm	1:16 on diameter	72 mm	1,523 psi
3	R3	Rc3	11	2.309 mm	87.88 mm	86.41 mm	84.93 mm	20.60 mm	29.80 mm	1:16 on diameter	84.75 mm	1,523 psi

Adapters with BSPT

NPT to BSPT adapters BSPT to BSPP adapters

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