Pipe fabrication drawings. Use of DN in BOM for Fab drawings.

[Andrew Larue]

Hello Gents

I have been in the fabrication field since 1993, fitters Tickets, welding tickets, Mechanical Eng Tech etc. All through my years for Fabrication drawings involving pipes, we never placed DN in the BOM describing it, it would either be Imperial or a Metric call out, such as Ø200 - Sch 40 - 2300 or Ø8" - Sch 40 - 2300 where 2300 was the length, sometimes we place the imperial in Brackets, but we never used the DN in front of it unless it was GA drawing for the customer. Most of the drawing I encountered for the Fab shop were done without the DN. I have heard different thoughts on this and I am curious as to what your thoughts are on this, is this the wrong approach? Should I be placing DN in there?

Very Curious on this.

Thank you for your answers.

 

[JStephen]

I had to google to see what DN was. (Nominal Diameter, if anyone else doesn't recognize it.)
With US units, with pipe, I usually use 8" Sch 160 or 6" XXS or whatever. It's understood that the dimension is the nominal diameter.
I avoid putting a diameter symbol in there with it as there's nothing on an 8" pipe that actually measures 8" diameter.
I notice with the structural tubing people, they tend to show actual OD, ID, etc. rather than nominal size, even if it is some standard size. I guess if you sell 6" that is 6.625" OD and also 6" that is 6.000" OD, you have no end of confusion by just calling both 6".
If you're detailing for a specific fab shop all the time, contact them, see what they need or what's clearest.