With respect to NPS 14 pipe and larger, how does the outside diameter behave as the pipe schedule increases?

The outside diameter of NPS 14 pipe and larger remains constant regardless of the increase in pipe schedule. This is because, for pipes designated in the Nominal Pipe Size (NPS) system, the outside diameter is fixed based on the nominal size. The schedule of a pipe primarily affects its wall thickness and, consequently, its internal diameter, but not the outside diameter. Therefore, as you increase the schedule of the pipe, you are increasing the wall thickness, but the outside diameter does not change. This consistency allows engineers and professionals in the field to standardize fittings and connections to NPS pipes without concern for variations in the outer dimension due to schedule changes.