Perhaps I posted this question in the wrong area but I will try again. I am a new MEP user. I am trying to become efficient with mechanical piping in 3D and have a problem with drawing piping vertically in a perspective view. When I first started I was able to do it but may have somehow turned off that capability and don't know how to turn it back on. I have a lot to learn but would appreciate any help on this issue. View the attachment if my description of the problem is not clear.
If you select the object, right click and bring up the menu to "edit in elevation" or section, you'll notice the UCS changes to the Y axis that was originally Z. You can draw in the Y axis in those views. Another way, if you're tipping the model from your original Z axis and want to draw in that view, type UCS, view, to put the UCS in the Y axis to draw.
The easiest method that I have found is to use the compass. When drawing pipe look at your command line, you should see an option for the compass. Make sure it is activated. Once activated you can use the plane command (also available on the command line while drawing pipe) to be able to change the current plane that the piping is being drawn on. This will not change your current ucs but will allow you to draw your pipe in any direction that you chose. The plane command will switch between the three standard planes.
Additionally, you can set up your compass by running the AecbCompass command on the command line. It is also available on the Ribbon under the View tab and then the MEP View panel.
In addition you can also change the slope of your pipe or use the elevation command to run your pipe to a specific elevation.
Hope this information will be of some use to you.