3 replies to this topic

[krishnamurthy]

what is the exact meaning of the nominal pipe diameter? generally if the size of the pipe is 4" what does it mean? whether it defines internal diameter or external diameter of the pipe. i think the nominal pipe diameter refers to the outer diameter of the pipe. But i am not sure, can u plz explain me about this.

[samayaraj]

Krishnamoorthy,

 

 

Nominal Pipe size (NPS), it neither indicates OD nor ID up to 12 inch. For pipe size 14 inch and above, NPS is equal to the OD of pipe. 

 

It is generally indicated as NPS or Nominal Bore (NB) or Diameter Nominal (DN).

 

1 inch = 25.4 mm. So, 1" NPS pipe is called as 25 NB pipe & the OD is 33.4 mm and for 10" NPS or 250 NB pipe, OD is 273 mm. So upto 10" NPS or 250 NB pipe, OD is not equal to NB of pipe.

 

But the above is not applicable for size greater than 12 inch pipe. From 12 inch above or 14 inch & above pipe size, pipe size is equal to OD of the pipe.

 

 

14" NPS or 350 NB pipe is equal to 14 x 25.4 = 355.6 mm.

16" NPS or 400 NB pipe is equal to 16 x 25.4 = 406.4 mm.

24" NPS or 600 NB pipe is equal to 24 x 25.4 = 609.6 mm.

 

Hope this is clear to you.

 

 

#Samayaraj

Edited by samayaraj, 14 July 2014 - 12:33 AM.

[oscarsender]

Its just a standard used in North American countries to designate pipe size. To determine the exact inner and outer diameter of the pipe, you should know also the schedule number of the pipe since schedule number has something to do with thickness. The European equivalent of NPS is DN (Diametre Nominal).

[xavio]

Krishnamurthy,

 

This kind of question is google-able.

http://en.wikipedia....minal_Pipe_Size

 

Good luck.

 

xavio