BSPT threaded pipe is a type of steel pipe manufactured with British Standard Pipe Taper threads on both ends. It provides a reliable threaded connection for industrial piping systems, fire protection, plumbing, and mechanical applications.
This guide explains BSPT thread standards, dimensions, manufacturing process, applications, and how to select a reliable BSPT threaded pipe supplier.
What Is BSPT Threaded Pipe? - R Thread
BSPT threaded pipe refers to a steel pipe with BSPT male threads machined on both ends. The pipe is connected with BSPT fittings such as elbows, tees, couplings, and valves through threaded connections.
BSPT stands for:
British Standard Pipe Thread
Unlike plain end steel pipes, BSPT threaded pipes have specially machined thread profiles at the pipe ends to provide a secure connection without welding.
BSPT Thread Specification- British Standard Pipe Thread
| Item | Specification |
| Full Name | British Standard Pipe Taper |
| Thread Type | Tapered Thread |
| Thread Angle | 55° |
| Taper | 1:16 |
| Male Thread Symbol | R |
| Female Thread Symbol | Rc |
| Thread Standard | ISO 7-1 / EN 10226 |
The diameter of BSPT threads gradually increases along the thread length. During tightening, the male and female threads create interference contact, forming a pressure-resistant seal.
BSPT Thread Dimension Table
BSPT is typically designated according to the ISO 7-1 system, with external tapered threads denoted by “R”; the thread angle is the 55° Whitworth profile, and the taper is 1:16 (on the diameter).
| BSPT Size | Thread Designation | TPI | Pitch P (mm) | Major Ø d (mm) | Pitch Ø d₂ (mm) | Minor Ø d₃ (mm) | Thread Height h (mm) |
|---|---|---|---|---|---|---|---|
| 1/16″ | R 1/16 | 28 | 0.907 | 7.723 | 7.142 | 6.561 | 0.581 |
| 1/8″ | R 1/8 | 28 | 0.907 | 9.728 | 9.147 | 8.566 | 0.581 |
| 1/4″ | R 1/4 | 19 | 1.337 | 13.157 | 12.301 | 11.445 | 0.856 |
| 3/8″ | R 3/8 | 19 | 1.337 | 16.662 | 15.806 | 14.950 | 0.856 |
| 1/2″ | R 1/2 | 14 | 1.814 | 20.955 | 19.793 | 18.631 | 1.162 |
| 3/4″ | R 3/4 | 14 | 1.814 | 26.441 | 25.279 | 24.117 | 1.162 |
| 1″ | R 1 | 11 | 2.309 | 33.249 | 31.770 | 30.291 | 1.479 |
| 1-1/4″ | R 1-1/4 | 11 | 2.309 | 41.910 | 40.431 | 38.952 | 1.479 |
| 1-1/2″ | R 1-1/2 | 11 | 2.309 | 47.803 | 46.324 | 44.845 | 1.479 |
| 2″ | R 2 | 11 | 2.309 | 59.614 | 58.135 | 56.656 | 1.479 |
| 2-1/2″ | R 2-1/2 | 11 | 2.309 | 75.184 | 73.705 | 72.226 | 1.479 |
| 3″ | R 3 | 11 | 2.309 | 87.884 | 86.405 | 84.926 | 1.479 |
| 4″ | R 4 | 11 | 2.309 | 113.030 | 111.551 | 110.072 | 1.479 |
| 5″ | R 5 | 11 | 2.309 | 138.430 | 136.951 | 135.472 | 1.479 |
| 6″ | R 6 | 11 | 2.309 | 163.830 | 162.351 | 160.872 | 1.479 |
The data below is derived from the standard document; in the event of any discrepancies, the data in the standard document shall prevail.
BSPT Threaded Pipe vs Plain End Steel Pipe
The main difference between BSPT threaded pipe and standard steel pipe is the pipe end design.
Plain End Steel Pipe
Steel Pipe
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Common end types:
- Plain End (PE)
- Beveled End (BE)
These pipes usually require welding, flanges, or mechanical couplings for connection.
BSPT threaded pipe
Steel Pipe
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BSPT Thread
The pipe ends undergo:
- Pipe end preparation
- Thread machining
- Thread dimension inspection
- Protective cap installation
Connection method:
BSPT Pipe
↓
BSPT Elbow
↓
BSPT Tee
↓
Valve
Key Features of BSPT Threaded Pipe
Tapered Thread Design
BSPT thread diameter increases gradually along the thread length.
- Better sealing performance
- Reduced leakage risk
- Suitable for pressure systems
Easy Installation
Wide Material Options
| Material | Application |
| Carbon Steel | General piping |
| Galvanized Steel | Fire sprinkler & water systems |
| Stainless Steel | Corrosive environments |
BSPT Threaded Steel Pipe Size Range
| Product Type | Size Range | Wall Thickness | Thread Type | Surface Treatment |
| Carbon Steel BSPT Pipe | 1/8″–6″ | SCH 10–SCH 80 | BSPT Male Thread | Black / Painted |
| Galvanized BSPT Pipe | 1/2″–6″ | SCH 10–SCH 80 | BSPT Male Thread | Hot Dip Galvanized |
| Fire Sprinkler BSPT Pipe | 1/2″–6″ | SCH 10–SCH 40 | BSPT / Customized | Galvanized / Coated |
BSPT Threaded Pipe Dimensions
Common BSPT threaded pipe sizes include:
R 1/2″ BSPT = 1/2-inch external tapered pipe thread
| Nominal Pipe Size (NPS) | BSPT Thread Designation | Outside Diameter (OD) | Threads Per Inch (TPI) | Approx. Thread Length |
| 1/8″ | R1/8 | 10.3 mm | 28 | 6.7 mm |
| 1/4″ | R1/4 | 13.7 mm | 19 | 9.7 mm |
| 3/8″ | R3/8 | 17.1 mm | 19 | 10.1 mm |
| 1/2″ | R1/2 | 21.3 mm | 14 | 13.2 mm |
| 3/4″ | R3/4 | 26.7 mm | 14 | 14.5 mm |
| 1″ | R1 | 33.4 mm | 11 | 16.8 mm |
| 1-1/4″ | R1-1/4 | 42.2 mm | 11 | 19.1 mm |
| 1-1/2″ | R1-1/2 | 48.3 mm | 11 | 19.1 mm |
| 2″ | R2 | 60.3 mm | 11 | 23.6 mm |
| 2-1/2″ | R2-1/2 | 75.2 mm | 11 | 26.7 mm |
| 3″ | R3 | 88.9 mm | 11 | 29.5 mm |
| 4″ | R4 | 114.3 mm | 11 | 32.5 mm |
| 5″ | R5 | 139.7 mm | 11 | 35.0 mm |
| 6″ | R6 | 165.1 mm | 11 | 39.0 mm |
Notes:
- BSPT thread dimensions are based on ISO 7-1 / EN 10226
- BSPT threads use a 55° Whitworth thread profilewith a 1:16 taper.
- Actual pipe outside diameter depends on the base pipe standard, such as ASTM A53, ASTM A795, EN 10255, or BS 1387.
- Threaded pipe sizes larger than 6 inches are less common and usually require customized processing.
The available pipe diameter and wall thickness depend on the base pipe standard, such as:
Applications of BSPT Threaded Pipe
Galvanized BSPT pipe is especially popular due to its corrosion resistance.
BSPT threaded connections are used in low and medium pressure gas applications where threaded joints are acceptable.
BSPT vs BSPP Thread
| Item | BSPT | BSPP |
| Full Name | British Standard Pipe Taper | British Standard Pipe Parallel |
| Thread Type | Tapered | Parallel |
| Symbol | R / Rc | G |
| Sealing Method | Thread interference sealing | Gasket/O-ring sealing |
| Application | Pipe connections | Instrument and hydraulic fittings |
BSPP is also known as G thread, while BSPT is a tapered pipe thread.
BSPT vs NPT Thread
| Item | BSPT | NPT |
| Origin | British standard | American standard |
| Thread Angle | 55° | 60° |
| Thread Profile | Whitworth | American National |
| Taper | 1:16 | 1:16 |
| Sealing | Thread sealing | Thread sealing |
Although BSPT and NPT look similar, they cannot be directly interchangeable because the thread profiles are different.
FAQ
Is BSPT the same as NPT?
No. BSPT uses a 55° thread angle, while NPT uses a 60° thread angle. They are different standards and cannot normally be mixed.
Can BSPT connect with BSPP?
No. BSPT and BSPP have different thread designs. BSPT uses tapered threads, while BSPP uses parallel threads.
What sizes are available for BSPT threaded pipes?
Common BSPT threaded pipe sizes range from 1/8 inch to 6 inches, depending on pipe standards and supplier capability.
Conclusion
BSPT threaded pipe provides a reliable and efficient connection solution for industrial piping, fire protection, plumbing, and mechanical systems.
Choosing a qualified BSPT threaded pipe manufacturer with advanced threading equipment, strict quality control, and complete inspection capability ensures consistent thread accuracy, leak-free performance, and long-term service reliability.
