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 2 3/4 (Internal Thread)
| Property |
Minimum |
Maximum |
| Minor Diameter (D1) |
78.577 mm (3.0936 ") |
79.217 mm (3.1188 ") |
| Pitch Diameter (D2) |
80.055 mm (3.1518 ") |
80.272 mm (3.1603 ") |
BSPP G 2 3/4-A (External Higher precision)
| Property |
Minimum |
Maximum |
| Major Diameter (d) |
81.1 mm (3.1929 ") |
81.534 mm (3.21 ") |
| Pitch Diameter (d2) |
79.838 mm (3.1432 ") |
80.055 mm (3.1518 ") |
BSPP G 2 3/4-A (External Low precision
| Property |
Minimum |
Maximum |
| Major Diameter (d) |
81.1 mm (3.1929 ") |
81.534 mm (3.21 ") |
| Pitch Diameter (d2) |
79.621 mm (3.1347 ") |
80.055 mm (3.1518 ") |
* For More Threadibg Information go to the BSP Thread Calculator
