| NB size | kg/m | kg per 6 m | OD × WT (mm) |
|---|---|---|---|
| 15mm (½") | 1.21 | 7.26 | 21.3 × 2.6 |
| 20mm (¾") ● | 1.56 | 9.36 | 26.9 × 2.6 |
| 25mm (1") | 2.41 | 14.46 | 33.7 × 3.2 |
| 32mm (1¼") | 3.10 | 18.60 | 42.4 × 3.2 |
| 40mm (1½") | 3.56 | 21.36 | 48.3 × 3.2 |
| 50mm (2") | 5.03 | 30.18 | 60.3 × 3.6 |
| 65mm (2½") | 6.42 | 38.52 | 76.1 × 3.6 |
| 80mm (3") | 8.38 | 50.28 | 88.9 × 4 |
| 100mm (4") | 12.18 | 73.08 | 114.3 × 4.5 |
| 125mm (5") | 16.62 | 99.72 | 139.7 × 5 |
| 150mm (6") | 20.11 | 120.66 | 168.3 × 5 |
| 200mm (8") | 33.05 | 198.30 | 219.1 × 6.3 |
A 20 NB (¾") medium-class MS pipe weighs 1.56 kg per metre, based on OD 26.9 mm and wall thickness 2.6 mm under IS 1239.
A standard 6 m length weighs 9.36 kg (1.56 kg/m × 6 m), roughly 106.8 lengths per tonne.
Under IS 1239 medium class, 20 NB corresponds to an outer diameter of 26.9 mm with a 2.6 mm wall. Light and heavy classes use the same OD with thinner or thicker walls.