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# Pipe Inverts at Structure Wall

## Pipe Inverts at Structure Wall

Pipes need to have their invert be at the outside of the structure's wall and not the center of the structure. This makes using the built in tables for pipes useless because it's not the true slope of the pipe.

Mentor

This one would have to be an option.

Here we need to calculate slope based on 2D length, Centre to Centre of the manholes. That's the municipal requirement.

Strange, as that wouldn't be the actual real slope of the pipe. BTW, I also work for our local government. We require the real pipe's slope. If you have an odd shaped structure that's large (8' at least), what do you consider the center of the structure?

Robert L. Soyars Jr.
Engineering Technician II
City of Johnson City
Public Works Department
Engineering Division
Phone: 423-232-5279

Think green: Only print this e-mail and any attachment if necessary.
Mentor

Here, I gave you a kudo! I'm not against this idea, I think you should have the option.

But we need the option of having it the way it is too.

I know exactly what you're saying; it is not the true slope of the pipe. The slope of the pipe will always be actually a little steeper than what we have on our drawings, and that's what the municipality requires. Who knows why?  Factor of safety on the slope and velocity calculations? I think part of it is that they want the quoted length to be centre-to-centre so that if you add up all the pipe lengths in a run you have the actual distance from end to end.  But why am I trying to guess at the reason behind municipal requirements? Seems kinda foolish on my part!

Perhaps this will help you. I posted a reply on exactly this topic yesterday, forgive me for not retyping it, but here's the link.

I think we need the CHOICE to be able to design an invert that falls ACROSS each manhole from wall to wall.  The added structure rle does not do that in a way that we can use since, when we create an alignment from network parts, the alignment does not go through the MH CL as has been done with pipes design since pipes were invented.

We spent several thousand dollars on a tool that does the work for us so that we get the answer we need on our profile views and can manage drops across manholes to suit our local authority requirements. Explanation here...http://forums.autodesk.com/t5/autocad-civil-3d-general/sewer-manhole-drops/td-p/5622186/page/2

I understood that in the US the requirement was for drops at CL, but have been informed recently that this is not the case with many municipalities.

Peter T

(New Zealand)

Contributor

You can right click on your pipe and use "Apply Rules" to make your pipe end at any defined part of your structure. I have mine set to end at the inside wall of the structure (to account for pipe penetration).

Oh?  This must be something new that I haven't found as yet.

I am using 2019 version tho.

Will look into it..

Cheers..

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