Pipe schedule primarily indicates which physical property?

• A. Wall thickness
• B. Outer diameter
• C. Pressure rating
• D. Thickness

Answer: (D)

Pipe schedule is a designation that tells you the wall thickness for a given nominal pipe size. For a fixed nominal size, the outer diameter stays essentially the same, while the wall thickness varies with schedule. That thickness is what controls the pipe’s strength and its ability to carry pressure, so the schedule is really a shorthand for how thick the walls are. The outer diameter is dictated by the size, not the schedule, and the pressure rating depends on thickness together with material and temperature, not directly on the schedule itself. So the property indicated by pipe schedule is the thickness (wall thickness).