C3D 2016 - Pressure Pipe Inner Diameter Issue

[Cadguru42]

Here's a strange one that is very problematic. I was in the middle of editing a pressure network by drawing pipes. All of a sudden the last 10" PVC pipe I went to create had the label show the size as 11". I deleted the pipe, re-created it and the same thing happened. So I checked the pipes I had just created before this and they all were correct. The next thing to check was the parts list, which now has incorrect inner diameters for ALL pressure pipes. This isn't limited to just a single parts list, either. Every parts list in C3D has an incorrect inner diameter that is the same or larger than the outside diameter. This is happening to multiple pipe materials and even different drawings. 

I have a screenshot that shows both the catalog properties as well as the 10" PVC pipe properties from the parts list in C3D. You can clearly see that the Diameter Inside (in) column in the Content Catalog Editor shows the size as 10, but in C3D the part shows the Inner Diameter the same as the Outer Diameter.

Here is another one showing the 12" ductile iron pipe having it's inner diameter larger than the outer diameter and doesn't match the catalog. 

This happened in the middle of me editing a pressure pipe network. The pressure catalog has not even been edited in over four weeks. I've closed the drawing, closed C3D, and even restarted the workstation. None of those have fixed this issue. What the heck is going on? I really need to get this working again as we've got a deadline coming up for a multi-billion dollar project.

[Mike_Hurtado]

I don't think you can edit the .sqlite file from Civil 3D so it's really weird that the change appears to have occurred while editing a network.

Can't think of anything else but changing the values back in the content catalog editor.

[Cadguru42]

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@mike_ADSK wrote:

I don't think you can edit the .sqlite file from Civil 3D so it's really weird that the change appears to have occurred while editing a network.

Can't think of anything else but changing the values back in the content catalog editor.

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I've gone almost a year using this catalog with a few added pipes, but never had an issue with the size of the pipes until this happened. I had a support request about this and we now know what it's doing, but not why it took a year to show up. 

Basically, C3D ignores the values of the inner diameter and the wall thickness of the pipe that's listed in the pressure network catalog for modeling. Instead, C3D reads the outer diameter and wall thickness of the connection points (whichever connection has the largest diameter). It takes the connection point's outer diameter and subtracts two times the connection point's wall thickness to come up with the inner diameter. That is the value that C3D sees and uses, except for when a pressure pipe is drawn in a profile view. In a profile view, C3D reads the pipe's outer diameter and the pipe wall thickness (not the connection point thickness) and draws the inside and outside walls correctly.

This is, IMHO, quite stupid. What's the point of having the user put values in the catalog if they're only going to be ignored? Why does C3D spend resources doing calculations when the values are given in the catalog already? Why did someone at Autodesk think that using the connection point values for a pipe would be the same as the actual pipe? Why does C3D read the inner diameter of the pipe for drawing in a profile view, but ignore it for everything else?

As to why C3D decided after almost 12 months to start doing these calculations, who knows? 

[dblanchard]

This bug appears to have re-emerged in 2026 SP2.  Just started happening today and I don't know why.  But my library now shows the inner diameter incorrectly.