Autodesk Revit MEP

[#1]

Why are pipes that pass through walls not showing as hidden, similar to a pipe below another pipe?  What's the best way to accomplish this?

[#2]

I don't *think* that it's possible to force the hidden lines onto Duct or Pipe elements passing through walls or other architectural elements. Are your intentions to show the piping like this on a project-wide scale, or just for a few details or enlarged plans?

[#3]

I would prefer it to be project wide.  Set it and forget it.

[#4]

I believe that you're out of luck here. Is it your company's standard to show the hidden lines regarding walls? I've only ever heard of anyone doing that once before, so I'm under the impression that this is uncommon enough so that the Revit design team either decided it wasn't worth the investment to cater to this need, or that they are unaware that anyone even shows MEP elements as being "hidden" behind walls and other architectural elements.