1/2" BSPT Thread
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1/2" BSPT (R 1/2") thread British tapered thread in hydraulics and pneumatics
1/2" BSPT thread (short for British Standard Pipe Tapered, designation R 1/2" for male external thread and Rc 1/2" for female internal thread) is a standardized British tapered pipe thread of the Whitworth form according to ISO 7-1, DIN 2999, and BS 21\. It is commonly used in power hydraulic systems, industrial pneumatics, water-gas installations, heating systems, and machine construction. It features a tapered profile with a 1:16 (6.25%) taper and a 55° thread angle. The connection seal occurs directly on the thread turns through mechanical pressing of the male cone (R 1/2") into a tapered seat (Rc 1/2") or a cylindrical one (G 1/2" / Rp 1/2"). For the 1/2" BSPT size, the thread pitch is 14 threads per inch (14 TPI / 1.814 mm pitch). The outer diameter of the male thread measured with a caliper ranges from 20.5 mm to 20.9 mm, while the internal diameter of the female thread is from 18.6 mm to 19.0 mm. The 1/2" BSPT thread is a common connection standard in pumps, valves, actuators, manifolds, and machine connectors of European and Asian production.
Application and technical characteristics of the 1/2" BSPT thread
Fastening components, adapters, and crimped ends with a 1/2" BSPT tapered thread (AGR-K / C31) are used in pressure circuits where a secure, self-sealing threaded connection resistant to high pressures, vibrations, and operating temperature spikes is required.
- Tapered sealing profile (1:16 taper): Enables achieving a seal directly on the thread turns using PTFE tape, hemp, or liquid anaerobic sealant.
- British Whitworth thread angle 55°: A standard characteristic of European pipe threads, distinguishing it from the American 1/2" NPT tapered thread (60° thread angle).
- Precise caliper measurements: The outer diameter of the male thread is 20.5–20.9 mm, and the female thread is 18.6–19.0 mm with a pitch of 14 threads per inch.
- Wide compatibility in pressure installations: Commonly used in shut-off valve bodies, manifold blocks, hydraulic power units, and pneumatic systems.
- Wide selection of fittings and adapters: The offer includes straight connectors, elbows, tees, reducers, and hose ends (AGR-K) with 1/2" BSPT thread.
Why choose components with 1/2" BSPT thread from the HYDRON store?
All fittings, adapters, and ends with 1/2" BSPT thread offered by the HYDRON store are manufactured according to strict ISO 9001 quality standard procedures from free-cutting steel protected with an anti-corrosive zinc coating and from AISI 316L stainless steel. Correct thread identification with a caliper is essential in workshop practice – confusing the 1/2" BSPT tapered thread with the American 1/2" NPT thread (despite the identical 14 TPI pitch) leads to a loss of seal due to the difference in thread angle (55° vs 60°). Furthermore, distinguishing BSPT (tapered) from BSPP (cylindrical G 1/2") allows for choosing the correct sealing method. For the construction and maintenance of hydraulic and pneumatic installations, we recommend selecting other compatible products from our offer, such as crimped hydraulic hoses and lines, matching AGR-K hose ends, durable hydraulic quick couplings and extensive hydraulic manifolds.
Technical specification
Technical parameter | Value / Description |
|---|---|
Thread designation | 1/2" BSPT / R 1/2" (male tapered) / Rc 1/2" (female tapered) |
Manufacturing standards | ISO 7-1, BS 21, DIN 2999, EN 10226 |
Outer diameter of male thread (caliper) | 20.5 mm – 20.9 mm |
Inner diameter of female thread (caliper) | 18.6 mm – 19.0 mm |
Thread pitch (number of turns per inch) | 14 threads per inch (14 TPI / 1.814 mm pitch) |
Thread angle and taper | 55° angle (Whitworth), 1:16 cone (6.25% taper) |
Sealing method | Seal on thread using PTFE tape, hemp, or liquid anaerobic glue |
Available materials and coating | Free-cutting/forged galvanized steel, AISI 316L stainless steel, brass |
Frequently Asked Questions (FAQ)
How to measure a 1/2" BSPT thread with a caliper?
By measuring the external male thread with a caliper, you will get a result in the range of 20.5–20.9 mm. In the case of the internal female thread, the hole diameter is 18.6–19.0 mm, and the thread gauge will show 14 threads per inch.
What is the difference between 1/2" BSPT and 1/2" BSPP (G 1/2") threads?
BSPT (R 1/2") thread is a tapered thread and seals directly on the turns. BSPP (G 1/2") thread is a cylindrical (straight) thread and requires sealing on the front face using a bonded seal (metal-rubber washer) or an O-ring.
Does the 1/2" BSPT thread fit a 1/2" NPT thread?
No. Although both threads have the same pitch of 14 threads per inch and a tapered profile, the BSPT thread has a 55° thread angle, while NPT has a 60° angle. Connecting them will lead to leakage and damage to the threads.
How to seal a connection with a 1/2" BSPT thread?
To seal a connection with a 1/2" BSPT tapered thread, professional PTFE Teflon tape, hemp with sealing paste, or liquid hydraulic thread sealants should be used.