Basic Thread Dimensions
*Â The below values are nomoinal (without tolerances) and are valid for both external and internal threads.
| Thread Family |
BSPP (G) |
| Relevant Standards |
ISO 228-1, ISO 228-2 |
Tolerances for all Classes
BSPP G 4 1/2 (Internal Thread)
| Property |
Minimum |
Maximum |
| Minor Diameter (D1) |
122.773 mm (4.8336 ") |
123.413 mm (4.8588 ") |
| Pitch Diameter (D2) |
124.251 mm (4.8918 ") |
124.468 mm (4.9003 ") |
BSPP G 4 1/2-A (External Higher precision)
| Property |
Minimum |
Maximum |
| Major Diameter (d) |
125.296 mm (4.9329 ") |
125.73 mm (4.95 ") |
| Pitch Diameter (d2) |
124.034 mm (4.8832 ") |
124.251 mm (4.8918 ") |
BSPP G 4 1/2-A (External Low precision
| Property |
Minimum |
Maximum |
| Major Diameter (d) |
125.296 mm (4.9329 ") |
125.73 mm (4.95 ") |
| Pitch Diameter (d2) |
123.817 mm (4.8747 ") |
124.251 mm (4.8918 ") |
* For More Threadibg Information go to the BSP Thread Calculator
