NPS 3-1/2 Pipe

Outside diameter 4.000″

OD in mm 101.6 mm

Every NPS 3-1/2 pipe has this OD regardless of schedule — the schedule changes only the wall thickness and bore.

Schedules

Schedule	Wall	Wall mm	Inside diameter	ID mm
40 = STD	0.226″	5.74	3.548″	90.119
80 = XS	0.318″	8.077	3.364″	85.446

Data provenance. ASME B36.10M, Welded and Seamless Wrought Steel Pipe (Table 2.1) (ASME). ID is derived: OD − 2 × wall. Dimensions are nominal; actual walls carry the standard's mill tolerance. See all data sources.