The inside diameters under IPS were roughly the same as the more modern Ductile Iron Pipe Standard (DIPS) and Nominal Pipe Size (NPS) Standards, and some of the wall thicknesses were also retained with a different designator.
The inside diameters in IPS standards were approximately equivalent to those found in the contemporary Ductile Iron Pipe Standard (DIPS) and Nominal Pipe Size (NPS) Standards, and certain wall thicknesses were retained using a different identifier.