Piping is sized:

Piping is sized:

• A. By its outer diameter
• B. By its nominal size and schedule
• C. By its wall thickness
• D. By its service pressure

Answer: (B)

Sizing piping uses the nominal size and the schedule. The nominal size (NPS) is the standard designation for the pipe’s size class, while the schedule specifies the wall thickness. The combination fixes the internal bore, which determines flow capacity, and the wall thickness, which determines the pressure rating and strength. The outer diameter is set by the nominal size, and changing the schedule changes the bore without changing the outer diameter, so two pipes with the same nominal size can have very different flow characteristics. Relying on outer diameter alone would misrepresent how much fluid can pass or how much pressure the pipe can safely handle. While service pressure influences which schedules are acceptable, it does not by itself define the size; the actual size comes from the nominal size together with the schedule.

Sizing piping uses the nominal size and the schedule. The nominal size (NPS) is the standard designation for the pipe’s size class, while the schedule specifies the wall thickness. The combination fixes the internal bore, which determines flow capacity, and the wall thickness, which determines the pressure rating and strength. The outer diameter is set by the nominal size, and changing the schedule changes the bore without changing the outer diameter, so two pipes with the same nominal size can have very different flow characteristics. Relying on outer diameter alone would misrepresent how much fluid can pass or how much pressure the pipe can safely handle. While service pressure influences which schedules are acceptable, it does not by itself define the size; the actual size comes from the nominal size together with the schedule.