Schedule 80 steel pipe thickness is the nominal wall thickness assigned to a steel pipe according to its NPS and applicable dimensional standard.
A common misunderstanding is that Schedule 80 represents one fixed wall thickness. It does not. Schedule 80 wall thickness changes with pipe size. A 1-inch Schedule 80 pipe and a 12-inch Schedule 80 pipe have different nominal wall thicknesses.
Schedule 80 Steel Pipe Thickness Chart
| NPS | OD | Schedule 80 Wall Thickness | Approx. ID |
| 1/2″ | 21.3 mm | 3.73 mm | 13.84 mm |
| 3/4″ | 26.7 mm | 3.91 mm | 18.88 mm |
| 1″ | 33.4 mm | 4.55 mm | 24.30 mm |
| 1-1/4″ | 42.2 mm | 4.85 mm | 32.50 mm |
| 1-1/2″ | 48.3 mm | 5.08 mm | 38.14 mm |
| 2″ | 60.3 mm | 5.54 mm | 49.22 mm |
| 2-1/2″ | 73.0 mm | 7.01 mm | 58.98 mm |
| 3″ | 88.9 mm | 7.62 mm | 73.66 mm |
| 4″ | 114.3 mm | 8.56 mm | 97.18 mm |
| 5″ | 141.3 mm | 9.53 mm | 122.24 mm |
| 6″ | 168.3 mm | 10.97 mm | 146.36 mm |
| 8″ | 219.1 mm | 12.70 mm | 193.70 mm |
| 10″ | 273.1 mm | 15.09 mm | 242.92 mm |
| 12″ | 323.9 mm | 17.45 mm | 288.99 mm |
| 14″ | 355.6 mm | 19.05 mm | 317.50 mm |
| 16″ | 406.4 mm | 21.44 mm | 363.52 mm |
| 18″ | 457.2 mm | 23.83 mm | 409.54 mm |
| 20″ | 508.0 mm | 26.19 mm | 455.62 mm |
| 24″ | 610.0 mm | 30.96 mm | 548.08 mm |
Why Is Schedule 80 Pipe Thicker?
The Schedule designation provides a standardized way of specifying pipe wall thickness in relation to nominal pipe size.
For a given NPS, a thicker wall generally provides:
- Greater resistance to internal pressure
- Greater resistance to external mechanical damage
- Higher section strength
- A larger corrosion allowance before the remaining wall becomes critical
However, a thicker Schedule does not automatically mean that a pipe is suitable for every high-pressure application. Pressure capability also depends on material grade, design temperature, allowable stress, weld quality, corrosion allowance, manufacturing standard, and the applicable design code.
