OD - Outside Diameter

Outside Diameter (OD) is the fundamental dimension used to categorize and specify the size of steel tubes and pipes, and it is a critical parameter in the hot-dip galvanizing process.

The Outside Diameter is the measurement of the external distance from one edge of the pipe to the opposite edge, passing through the center. Unlike the Nominal Bore (NB) or Nominal Pipe Size (NPS)—which are industry labels representing the approximate internal carrying capacity—the OD is a fixed, physical dimension regardless of the pipe's wall thickness.