How can we relate DN and NPS…???

Thank you,

Regards,

Sabir

Sabir,

These are different terms for expressing pipe size.

The size of pipes, fittings, flanges and valves are often given in inches as NPS - Nominal Pipe Size, or in metric units as DN - "Diametre Nominel"

It is common to identify pipes by inches using NPS or "Nominal Pipe Size". 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.

The use of NPS does not conform to American Standard pipe designations where the term NPS means "National Pipe Thread Straight".

Also, (and I might not be correct on this), but for NPS sizes (up to 14" or so) the OD of the pipe is greater than the NPS, eg for a 2" NPS the OD is 2.375" and the wall thickness / schedule is taken off this OD, giving a 'nominal' neutral axis of 2", whereas in DN sizes the line size stated is always the OD (ie DN80 is 80mm Outside Diameter).??

That's not true.

The DN80 (or NPS 3) has OD of 89 mm.

For NPS 14 (or DN350) and larger, the NPS (or DN) is equal to the outside diameter (OD) in inch (or mm)

I stand corrected!!!

But I did say I might not be right on this!!