Nominal Pipe Size (NPS) is a North American set of standard sizes for pipes and fittings used for high or low pressures and temperatures. Pipe size is specified with two non-dimensional numbers a nominal pipe size (NPS) for diameter based on inches, and a schedule (Sched. or Sch.) for wall thickness. The name NPS is based on the earlier Iron buy carbon steel pipe standards buy carbon steel pipe standards astm pipe specification chart carbon steel pipe standard weight carbon steel pipe weight chart carbon steel pipe specifications carbon steel pipe dimension carbon steel pipe sizes carbon steel pipe material specification astm pipe standards chart