BSPT Thread Chart ( British Standard Pipe Taper )
Looking for a BSPT thread chart/ British Standard Pipe Taper Thread chart?
The chart below provides the most commonly used BSPT thread sizes according to ISO 7-1 and BS 21 standards. Engineers, buyers, and maintenance teams use these dimensions to verify thread compatibility before purchasing pipes, fittings, valves, and instrumentation components.
BSPT Thread Dimension Chart (ISO 7-1)
| BSPT Size | Major Diameter (mm) | Pitch (mm) | TPI | Pitch Diameter (mm) | Minor Diameter (mm) | Thread Height (mm) |
|---|---|---|---|---|---|---|
| 1/16″ | 7.723 | 0.907 | 28 | 7.142 | 6.561 | 0.581 |
| 1/8″ | 9.728 | 0.907 | 28 | 9.147 | 8.566 | 0.581 |
| 1/4″ | 13.157 | 1.337 | 19 | 12.301 | 11.445 | 0.856 |
| 3/8″ | 16.662 | 1.337 | 19 | 15.806 | 14.950 | 0.856 |
| 1/2″ | 20.955 | 1.814 | 14 | 19.793 | 18.631 | 1.162 |
| 3/4″ | 26.441 | 1.814 | 14 | 25.279 | 24.117 | 1.162 |
| 1″ | 33.249 | 2.309 | 11 | 31.770 | 30.291 | 1.479 |
| 1-1/4″ | 41.910 | 2.309 | 11 | 40.431 | 38.952 | 1.479 |
| 1-1/2″ | 47.803 | 2.309 | 11 | 46.324 | 44.845 | 1.479 |
| 2″ | 59.614 | 2.309 | 11 | 58.135 | 56.656 | 1.479 |
| 2-1/2″ | 75.184 | 2.309 | 11 | 73.705 | 72.226 | 1.479 |
| 3″ | 87.884 | 2.309 | 11 | 86.405 | 84.926 | 1.479 |
| 4″ | 113.030 | 2.309 | 11 | 111.551 | 110.072 | 1.479 |
BSPT Thread Drill Size Chart
| BSPT Size | Tap Drill Diameter (mm) |
|---|---|
| 1/8″ | 8.4 |
| 1/4″ | 11.2 |
| 3/8″ | 14.75 |
| 1/2″ | 18.25 |
| 3/4″ | 23.75 |
| 1″ | 30 |
| 1-1/4″ | 38.5 |
| 1-1/2″ | 44.5 |
| 2″ | 56 |
| 2-1/2″ | 71 |
| 3″ | 85.5 |
| 4″ | 110.5 |
BSPT Thread Quick Identification Chart
| Size | TPI | Pitch (mm) |
|---|---|---|
| 1/8″ | 28 | 0.907 |
| 1/4″ | 19 | 1.337 |
| 3/8″ | 19 | 1.337 |
| 1/2″ | 14 | 1.814 |
| 3/4″ | 14 | 1.814 |
| 1″–6″ | 11 | 2.309 |
BSPT Thread Specifications
Before selecting a threaded pipe or fitting, it is important to understand the basic BSPT thread characteristics.
| Item | BSPT Specification |
| Thread Standard | ISO 7-1 |
| British Standard | BS 21 |
| Thread Type | Tapered |
| Thread Angle | 55° |
| Taper Ratio | 1:16 |
| Sealing Method | Thread Interference |
| Common Applications | Pipes, Fittings, Valves, Instrument Connections |
Key Point: BSPT is a tapered thread designed to seal through thread engagement. It differs from BSPP, which uses a parallel thread profile.
Common BSPT Thread Applications
BSPT threads are widely used in industrial piping systems worldwide.
Typical applications include:
- Carbon steel pipe systems
- Galvanized steel pipe installations
- Stainless steel pipe systems
- Water distribution networks
- Fire protection systems
- Compressed air pipelines
- Instrument tubing connections
- Oil and gas utility piping
In many international projects, BSPT remains the preferred thread standard across Europe, Asia, Australia, Africa, and the Middle East.
BSPT vs BSPP vs NPT
Choosing the wrong thread standard is one of the most common causes of leakage and installation failures in piping systems.
Although BSPT, BSPP, and NPT threads may appear similar, their sealing methods and thread profiles are different.
Before ordering threaded pipes, fittings, valves, or instrumentation components, it is important to verify the thread standard.
BSPT vs BSPP vs NPT Comparison Chart
| Feature | BSPT | BSPP | NPT |
|---|---|---|---|
| Full Name | British Standard Pipe Taper | British Standard Pipe Parallel | National Pipe Thread |
| Thread Type | Tapered | Parallel | Tapered |
| Thread Angle | 55° | 55° | 60° |
| Standard | ISO 7-1 | ISO 228 | ASME B1.20.1 |
| Taper Ratio | 1:16 | None | 1:16 |
| Sealing Method | Thread Interference | O-Ring / Washer | Thread Interference |
| Common Markets | Europe, Asia, Australia | Europe, Asia | North America |
| Interchangeable | No | No | No |
How to Identify a BSPT Thread
Step 1: Measure Thread Pitch
Use a thread gauge and verify the TPI.
Step 2: Measure Major Diameter
Measure the male thread outside diameter with a digital caliper.
Compare the result with the BSPT thread chart above.
Step 3: Confirm the Taper
BSPT threads use a 1:16 taper ratio.
If the diameter increases toward the thread base, it is likely BSPT.
If the diameter remains constant, it is likely BSPP.
Common Purchasing Mistakes
The most common BSPT-related procurement errors include:
- Ordering BSPP instead of BSPT
- Mixing BSPT and NPT fittings
- Using nominal size as the only reference
- Ignoring thread standards in technical drawings
- Failing to verify dimensions before production
A simple thread verification process can prevent installation delays and replacement costs.
Need BSPT Threaded Steel Pipes or Fittings?
Selecting the correct BSPT thread is critical for leak-free installation and long-term system reliability.
UNIACERO supplies threaded carbon steel pipes, galvanized steel pipes, stainless steel pipes, couplings, nipples, and customized threaded fittings manufactured according to international standards.
If you are unsure whether your project requires BSPT, BSPP, or NPT threads, send us your drawings or specifications. Our engineering team can help verify thread dimensions, compatibility, and manufacturing requirements before production begins.
FAQ
1. What does BSPT stand for?
British Standard Pipe Taper.
2. What standard defines BSPT threads?
ISO 7-1 and BS 21.
3. What is the BSPT thread angle?
55 degrees.
4. Is BSPT the same as BSPP?
No. BSPT is tapered, while BSPP is parallel.
5. Is BSPT compatible with NPT?
No. The thread profile and angle are different.
6. What is the BSPT taper ratio?
1:16.
7. How do I identify a BSPT thread?
Measure thread pitch, major diameter, and taper.
8. Where are BSPT threads commonly used?
Pipes, fittings, valves, compressed air systems, water systems, and instrumentation connections.