GB 838 – 1988 – Bu lông lục giác
| Screw Thread | M5 | M6 | M8 | M10 | M12 | (M14) | M16 | |
| d | ||||||||
| P | Pitch | 0.8 | 1 | 1.25 | 1.5 | 1.75 | 2 | 2 |
| b | 8 | 10 | 12 | 15 | 18 | 20 | 24 | |
| ds | max | 3.5 | 4.5 | 5.5 | 7 | 9 | 11 | 12 |
| min | 3.32 | 4.32 | 5.32 | 6.78 | 8.78 | 10.73 | 11.73 | |
| s | max | 8 | 10 | 13 | 16 | 18 | 21 | 24 |
| min | 7.78 | 9.78 | 12.73 | 15.73 | 17.73 | 20.67 | 23.67 | |
| k | Nominal Size | 3.5 | 4 | 5.3 | 6.4 | 7.5 | 8.8 | 10 |
| max | 3.65 | 4.15 | 5.45 | 6.58 | 7.68 | 8.98 | 10.18 | |
| min | 3.35 | 3.85 | 5.15 | 6.22 | 7.32 | 8.62 | 9.82 | |
| e | min | 8.79 | 11.05 | 14.38 | 17.77 | 20.03 | 23.35 | 26.75 |
| c | 1.6 | 2 | 2.5 | 3 | 4 | 5 | 6 | |
| Weight of per 1000 steel products(≈kg) | – | – | – | – | – | – | – | |
