NPS 14 (DN 350) Pipe — Dimensions, Schedules & Weight
Welded and seamless steel pipe per ASME B36.10M / EN 10220
NPS 14 (DN 350) pipe always has an outside diameter of 355.6 mm (14") — the schedule changes only the wall, from 6.35 mm at Sch 10 to 35.71 mm at Sch 160. That is the whole logic of the schedule system: OD stays constant so fittings and threads always match, while a higher schedule buys pressure capacity with a thicker wall and a smaller bore.
The most-quoted variant, Sch 30 / STD, has a 9.53 mm wall, a 336.5 mm inside diameter, and weighs 81.33 kg/m — a 6 m length is 488 kg. All weights below are plain-end masses from the standard formula (OD − t) × t × 0.02466.
NPS 14 (DN 350) pipe, Sch 30 / STD: cross-section drawn to scale (OD 355.6 mm, wall 9.53 mm, ID 336.5 mm)NPS 14 (DN 350) — all schedules
| Schedule | t (mm) | t (in) | ID (mm) | kg/m | lb/ft |
|---|
| Sch 10 | 6.35 | 0.25 | 342.9 | 54.69 | 36.75 |
| Sch 20 | 7.92 | 0.312 | 339.8 | 67.9 | 45.63 |
| Sch 30 / STD | 9.53 | 0.375 | 336.5 | 81.33 | 54.65 |
| Sch 40 | 11.13 | 0.438 | 333.3 | 94.55 | 63.53 |
| Sch XS | 12.7 | 0.5 | 330.2 | 107.39 | 72.16 |
| Sch 60 | 15.09 | 0.594 | 325.4 | 126.71 | 85.15 |
| Sch 80 | 19.05 | 0.75 | 317.5 | 158.1 | 106.24 |
| Sch 100 | 23.83 | 0.938 | 307.9 | 194.96 | 131.01 |
| Sch 120 | 27.79 | 1.094 | 300 | 224.65 | 150.96 |
| Sch 140 | 31.75 | 1.25 | 292.1 | 253.56 | 170.38 |
| Sch 160 | 35.71 | 1.406 | 284.2 | 281.7 | 189.29 |
Frequently Asked Questions
What is the outside diameter of 14" pipe?
355.6 mm (14 inches) — for every schedule. NPS is a nominal name, not a measurement. From NPS 14 up, OD equals the NPS in inches.
What is the wall thickness and ID of 14" Sch 30 / STD?
Sch 30 / STD has a 9.53 mm (0.375") wall, which leaves an inside diameter of 336.5 mm. The table above lists the wall and bore for every schedule of this size.
How much does 14" Sch 30 / STD pipe weigh?
81.33 kg/m (54.65 lb/ft). A 6 m length weighs 488 kg, a 12 m length 976 kg. The heaviest listed schedule, Sch 160, weighs 281.7 kg/m.
What is the difference between STD and Schedule 40?
Up to NPS 10 they are the same wall. From NPS 12 upward they split: STD stays at 9.53 mm (3/8") for all larger sizes, while Sch 40 keeps growing with the diameter. The same happens to XS and Sch 80 above NPS 8.
Values are entered from the governing standard’s published tables and cross-checked programmatically against its mass and section formulas before publication. Spotted an error? Write to advertising@metalabout.net — verified corrections ship within days. About