DN vs NPS: Pipe OD Conversion Table for ASME, EN, JIS and KS Flanges

Many engineers and buyers assume that DN represents the actual pipe diameter.

It doesn't.

DN and NPS are nominal size designations used by different piping standards.

For example:

• DN50 = NPS 2"

• DN100 = NPS 4"

• DN200 = NPS 8"

However, the actual pipe outside diameter (OD) is what matters when selecting a flange.

A DN50 / NPS 2" pipe has an OD of 60.3 mm.

Selecting a flange based only on DN without checking the applicable standard can lead to costly procurement mistakes.

To help engineers, buyers, and project teams quickly cross-reference international piping standards, we've created a free DN to NPS Conversion Table.

✓ ASME B16.5

✓ ASME B16.47

✓ EN 1092-1

✓ JIS B2220

✓ KS B1503

✓ GB/T

👉 Check the free tool:

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