| Internal Dia.(in) | MIN WALL | LB/FT |
|---|---|---|
| 12 | 1-3/4″ | 90 |
| 15 | 1-7/8″ | 120 |
| 18 | 2″ | 160 |
| 21 | 2-1/4″ | 210 |
| 24 | 2-1/2″ | 270 |
| 27 | 2-5/8″ | 310 |
| 30 | 2-3/4″ | 360 |
These tables are based on concrete weighing 150 pounds per cubic foot and will vary with heavier or lighter weight concrete.
| Internal Dia.(in) | MIN WALL | LB/FT |
|---|---|---|
| 12 | 2″ | 110 |
| 15 | 2-1/4″ | 150 |
| 18 | 2-1/2″ | 200 |
| 21 | 2-3/4″ | 260 |
| 24 | 3″ | 330 |
| 27 | 3-1/4″ | 390 |
| 30 | 3-1/2″ | 450 |
These tables are based on concrete weighing 150 pounds per cubic foot and will vary with heavier or lighter weight concrete.