DIMENSIONAL DIFFERENCES IN PIPE SIZE

Nominal Pipe Size (NPS)

The term used as a guideline number defining the diameter
of the pipe. Nominal pipe size refers to only the outside diameter (OD) of a pipe.

Nominal Bore (NB)

The European designation equivalent to NPS, in which sizes are measured in millimetres. NB (nominal bore) is also frequently used interchangeably with NPS.

Diameter Nominal (DN)

The international and European metric method used to describe NPS (or NB).
DN pipe sizes numbers are therefore different to NPS.

Outside Diameter (OD)

OD is the outside diameter of the pipe and is fixed for a given size. The NPS is related to the inside diameter
in inches

order	DN DIAMETER NOMINAL	NPS NOMINAL PIPE SIZE	NB NOMINAL BORE	OD OUTSIDE DIAMETER
1	15	1/2 INCH	15	21.3
2	20	3/4 INCH	20	26.7
3	25	1 INCH	25	33.4
4	40	1.5 INCH	40	48.3
5	50	2 INCH	50	60.3
6	80	3 INCH	80	88.9
7	100	4 INCH	100	114.3
8	125	5 INCH	125	141.3
9	150	6 INCH	150	168.2
10	200	8 INCH	200	219
11	250	10 INCH	250	273
12	300	12 INCH	300	323.8
13	350	14 INCH	350	355.6
14	400	16 INCH	400	406.4
15	450	18 INCH	450	457.2
16	500	20 INCH	500	508
17	600	24 INCH	500	609.6

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