If you are encountering issues with the Analyze Gravity Network command, please refer to the following list and also see About Analyzing and Sizing a Gravity Pipe Network and ensure that the prerequisites listed in the Workflow Prerequisites section have been met.
- Any non-circular pipe is handled as a circular pipe during the analysis. The inner width is used as the diameter.
- If the selected pipe network is data-referenced, the energy and hydraulic grade lines can be computed, but analysis results cannot be applied to the pipe network.
- The minimum cover specified in the Settings applies to all pipes except the most downstream pipe (connected to the outfall structure). This may result in the outfall structure and its connected pipe appearing above ground when the surface slope is steeper than the slope of the most downstream pipe, unless you select the Hold Outfall Invert check box on the General page. The Hold Outfall Invert setting will hold the elevation at the outfall, and the elevations of the rest of the pipe network may be lowered based on the calculated pipe slopes.
- The minimum cover value as specified in the Settings is measured down to the (inside) crown of the pipe. It does not take into consideration the thickness of the pipe itself. If you need to account for the thickness of the pipe you can adjust the minimum cover value. The minimum cover values reported on the Results page are reported to the top of the pipe, so those reported values will be approximately equal to the minimum cover value as specified on the Settings page minus the pipe thickness.
Issue Configuring Manning's N Coefficient for Concrete Pipes
Parts lists in drawings that were created from older templates may contain concrete pipe parts that do not have configurable Manning's n coefficients. You may experience issues running the Analyze Gravity Network command on pipe networks that contain these parts.
For example, if you attempt to run the Analyze Gravity Network command on such a pipe network, you may see that the Manning's n coefficient is set to an invalid number on the Network Details page, but if you attempt to change the Manning's n coefficient value, the change is not applied.
To address this issue, you can perform the following steps.
- Open the drawing that contains the pipe network.
- In Toolspace, on the Settings tab, expand Pipe Networks
Parts Lists.
- Right-click the parts list that is used for the affected pipe network Edit.
- In the Network Parts List dialog box, click the Pipes tab.
- Expand the Concrete Pipe part family.
- Delete the existing concrete pipe sizes by right-clicking each one Delete.
- Add the concrete pipe sizes back into the parts list by right-clicking Concrete Pipe Add Part Size.
- If the parts list contains only concrete parts, add another part family to the parts list and add a single part size to it. You can swap the concrete parts to this part temporarily before swapping them back to concrete parts. This temporary part family can be removed after swapping the parts.
- Save the parts list.
- In the drawing, select an existing concrete pipe.
- Right-click Swap Part.
- Select a part that is not a concrete part type and click OK.
- Select the pipe again. Right-click Swap Part.
- Select the concrete part type and click OK.
- Repeat steps 10-14 for each concrete pipe in the drawing.
- Edit the parts list and remove the temporary part family if you added one in step 8 above.