Nominal NB Pipe Sizes Chart

Posted by Steel Guru on August 2nd, 2022

A North American set of standard sizes for pipes used for high or low pressures and temperatures is known as nominal pipe size (NPS). The older "Iron Pipe Size" (IPS) system provides the basis for the name NPS. The pipe size was designated using the IPS system. The size was an estimate of the pipe's internal diameter in inches. A pipe with an IPS 6" interior diameter has an inside diameter of around 6 inches. People began referring to the pipe as 2-inch, 4-inch, 6-inch pipe, and so forth. Each pipe size was first manufactured with a single thickness that was later known as standard (STD) or standard weight (STD.WT.). The pipe's exterior diameter was standardized.

Nominal NB Pipe Schedule:

Therefore, only three wall thicknesses were in use at the time of IPS. The American Standards Association conducted an industry assessment in March 1927 and developed a technique for identifying wall thicknesses based on reduced steps between sizes. Iron pipe size was superseded by the notation known as nb pipe sizes chart, and the term schedule (SCH) was created to describe the nominal wall thickness of the pipe. We are now aware of a range of wall thicknesses thanks to the addition of schedule numbers to the IPS specifications.

Nominal NB Pipe Summary:

  • Pipe size is specified with two non-dimensional numbers
  • nominal pipe size (NPS)
  • schedule number (SCH)
  • and the correlation between these figures establishes a pipe's interior diameter.

Dimensions for stainless steel nb pipes, including outer diameter and schedule wall thickness, are established by ASME B36.19. Keep in mind that all stainless wall thicknesses to ASME B36.19 end in "S". Suffix-free sizes to adhere to ASME B36.10, which is designed for carbon steel pipes. An additional approach with a dimensionless designator is used by the International Standards Organization (ISO).

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