NPS 6 Pipe

Outside diameter 6.625″

OD in mm 168.275 mm

Every NPS 6 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	0.280″	7.112	6.065″	154.051
80 = XS	0.432″	10.973	5.761″	146.329

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.