Whitworth Pipe Threads
The Whitworth thread specifies a 55° thread angle and a thread depth of 0.640327p and a radius of 0.137329p where p is the pitch.
The most common types of Whitworth pipe threads are
- BSPP (G) – British Standard Pipe Parallel - see ISO 228 Pipe Threads where Pressure-tight Joints are not made on the Threads
- BSPT (R/Rp) – British Standard Tapered Pipe for pipes and tapered threads - see ISO 7 - Pipe Threads where Pressure-tight Joints are made on the Threads
In the UK metric ISO threads have replaced Withworth (BSW) and British Standard Fine (BSF) threads. In USA the most common threads are "Unified Fine" (UNF) and "Unifed Coarse" (UNC).
BSPP (G) – British Standard Pipe Parallel
| Thread size (inch) | Major Diameter (mm) | Minor Diameter (mm) | TPI |
|---|---|---|---|
| G 1/16 | 7.723 | 6.561 | 28 |
| G 1/8 | 9.728 | 8.566 | 28 |
| G 1/4 | 13.157 | 11.445 | 19 |
| G 3/8 | 16.662 | 14.950 | 19 |
| G 1/2 | 20.955 | 18.631 | 14 |
| G 3/4 | 26.441 | 24.117 | 14 |
| G 1 | 33.249 | 30.291 | 11 |
| G 2 | 59.614 | 56.656 | 11 |
- TPI = threads per inch
BSPT (R/Rp) – British Standard Tapered Pipe
| Male Thread size (inch) | Female Thread size (inch) | Major Diameter (mm) | Minor Female Diameter (mm) | TPI |
|---|---|---|---|---|
| R 1/16 | Rp 1/16 | 7.723 | 6.490 | 28 |
| R 1/8 | Rp 1/8 | 9.728 | 8.495 | 28 |
| R 1/4 | Rp 1/4 | 13.157 | 11.341 | 19 |
| R 3/8 | Rp 3/8 | 16.662 | 14.846 | 19 |
| R 1/2 | Rp 1/2 | 20.955 | 18.489 | 14 |
| R 3/4 | Rp 3/4 | 26.441 | 23.975 | 14 |
| R 1 | Rp 1 | 33.249 | 30.111 | 11 |
| R 2 | Rp 2 | 59.614 | 56.476 | 11 |
- BSPT male threads seal against threads of fixed BSPT female.
- BSPT male and BSPP male with conical 30° seat seal against matching conical 30° seat of BSPP female swivel.
Related Topics
• Threads
Thread data - metric, unified, ACME and others.
Related Documents
ANSI B1.20.1 - NPT - American National Standard Taper Pipe Threads
NPT and NPTF pipe threads - dimensions according ANSI/ASME B1.20.1/3.
British Standard Brass Threads
British Brass Thread is an imperial unit based screw thread.
British Standard Cycle Threads
British Standard Cycle is a British Imperial screw thread standard.
BS 21 - Pressure Tight Pipe Thread Joints
BSPT - British Standard Pipe Taper threads & BSP or BSPF - British Standard Pipe Parallel (Straight) threads.
EN 10226 - Pipe Threads where pressure tight joints are made on the threads - Dimensions
Pipe threads where pressure tight joints are made on the threads - Part 1: Taper external threads and parallel internal threads.
ISO 228 - Pipe Threads where Pressure Tight Joints are not made on the Threads
Requirements for thread form, dimensions, tolerances and designation for fastening pipe threads, thread sizes.
ISO 7 - Pipe Threads where Pressure-tight Joints are made on the Threads
Pressure-tight joints made on the pipe threads.
ISO 724 - Metric Threads
Dimensions of metric threads according ISO 724.
Piping Thread Standards
Applied threaded standards used for piping connections.
Threads commonly used in Piping
Piping thread standards.
UNC and UNF - Unified Coarce and Unified Fine Inch Threads
ANSI/ASME B1.1 Unified National Thread - UNC Coarse series and UNF Fine series.