Metric Pipe Sizes Dn "Diametre Nominel" per ISO vs NPS "Nominal Pipe Size" Equivalent for DN 6 to DN 2200, NPS Schedule 5 to 30. Welded and Seamless PIpe

The metric equivalent is called DN or "diametre nominel". The metric designations conform to International Standards Organization (ISO) usage and apply to all plumbing, natural gas, heating oil, and miscellaneous piping used in buildings.

DN gives a rough estimate of the internal diameter of a pipe. It doesn’t directly correlate to the actual OD or ID but is close to ID for larger pipes. Not directly related to pipe diameter but is an indicator of pressure handling capability.

Conversion table DN to inch NPS showing the equivalences that exist when measuring a pipe between nominal pipe diameter and NPS

Based on ASME standards. Please refer to your supplier’s datasheets for certain values.

Metric to Pipe Conversion Chart Diameter Nominal DN (mm) Nominal Pipe Size NPS (in.) 6 0.125 8 0.25 10 0.375 15 0.50 20 0.75 25 1.00 32 1.25

Nominal pipe size: DN32 Standard: EN10220 Inside diameter [mm] Wall thickness [mm] Mass per unit length [kg/m] 41.4 0.5 0.517 41.2 0.6 0.619 40.8 0.8 0.821 40.4 1 1.02 40 1.2 1.22 39.6 1.4 1.42 39.2 1.6 1.61 38.8 1.8 1.8 38.4 2 1.99 37.8 2.3 2.27 37.2 2.6 2.55 36.6 2.9 2.82 36 3.2 […]

Oct 10, 2022 · Diametre Nominal (DN) is based on millimetres and is standardized in ISO 6708 "Pipework components - Definition and selection of DN (nominal size)" A general rule of thumb for NPS vs DN is to divide DN by 25 for NPS when not using reference table.

Consult a pipe sizing chart to determine the nearest DN or NPS value. Finding the size of a female pipe fitting is much simpler, and only requires a ruler and a calculator. Measure the inside diameter of the pipe across the opening.

DN is defined by the European standard ISO 6708 and is based on millimeters. It represents the approximate internal diameter of a pipe. DN values are typically expressed as whole numbers (e.g., DN 50).