NPS 4

[greg211]

hi all, please is there any formular or method i can apply to get the outside diameter of a pipe given the norminal pipe size.without the aid of a table.

thanks

 

[BigInch]

Memorization and total recall in manual mode, or lookup function when using Excel.

http://virtualpipeline.spaces.msn.com

"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain

 

[JohnBreen]

Greg,

No there is no equation because there is no rational reason. We have what we have (from the old IPS days) and it has been that way so long that we cannot change it now.

BigInch, you will love this one (I got it from a thread in the ASME Code discussion):

Interpretation: 2-10
Subject: Outside Diameter Tolerances
Date Issued: July 3, 1990

Question (1): Does B16.5-1988 have any requirements for tolerances on flange outside diameters?

Reply (1): No.

Question (2): Why not?

Reply (2): The ASME B16 Committee does not respond to questions about rationale for requirements.



John

 

[zdas04]

It just doesn't get any clearer than that.

 

[BigInch]

That's a good one John!
I've archived it for future reference.

http://virtualpipeline.spaces.msn.com

"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain

 

[IFRs]

For what it's worth, I like this web site:

http://www.onlinepipe.com/pipechart.html

 

[JohnBreen]

IFRs

Thanks that is a good one.

John

 

[ccoughran]

There is no simple formula due to the multiple schedules and the evolutionary nature of the standards. However, it is not difficult to memorize everything you need. First of all, the OD of all pipe sizes above 12" is the same as the nominal size. 14" pipe is 14" OD. That takes care of the majority of the pipe sizes.

If you eliminate the infrequently used sizes, e.g. 2 1/2 etc., you are down to 13 sizes or so. 10" and 12" have ODs 0.750 larger than the nominal ID. That is, 12" pipe has an OD of 12.750. 6" and 8" have ODs 0.625 larger than the nominal ID.

That brings you down to 11 sizes or so to remember. The numbers get odder as you go down in pipe size due to historical factors, but I it not a huge task to memorize them.

 

[11echo]

I guess I have to state the obvious here Greg, when you are dealing with pipe,the O.D. ALWAYS stays the same. When the schedule (wall thickness) changes, only the I.D. changes ...then you'll need your tables. Good Luck!