Are you trying to do this specifically in SW Routing? If so, then I probably can't help you. However, if you are NOT doing this in routing then maybe the following will help.
A few questions:
How are you creating your piping?
Are you using a weldment structural member?
If so, then maybe you can create a 2nd structural member that is basically an offset inward of the thickness coating. Then just use the same path that you used for the original pipe.
Are you using sweeps to create the piping?
If so, then doing something similar to the above will work. Just use another profile that is offset from the original and then use the same sweep path.
Are you modeling each individual pipe section, then assembling it?
If so, the next question is, do you want the coating to be a separate part in a separate file, or a separate body in the same file?
If separate part, then create a new part, and then insert your original pipe part (this will link your original pipe to this new part). Then just select the inside of the pipe and offset surface 0in thick. Then thicken that inward the thickness of your coating. Then select the original pipe body (in the "Solid Bodies" folder) and select delete. This will add a new feature of delete body.
If a separate body in the same part, then do the same thing, just do it right inside the same part....remember to deselect the "merge Faces" check box.
Since you are using this in Routing, you can create an entirely new Pipe.SLDPRT and an entirely new and complete Routing Specification, which both include dual materials in the Pipe.PLDPRT file. I'd make it not only in a new location, but clearly named LayeredPipe or Pipe2 or LinedPipe or such.
Covering in Routing cannot go inside the pipe (AFAIK). Covering only covers the outside of the pipe, and typically skips fittings, valves, and other non-pipe or elbow stuff. As you've noted, it is not very pretty.
Without creating a complete new Routing Specification with library and pipe, that is, if you are not going to be using this commonly, but only need it added to This project, Dan Pihlaja's tips are spot-on. I've used all of his suggestions here before (most often surface offset and thicken), depending on context of component, Routing subassembly, or pipe, for teflon lined pipe, tees, tanks (w nozzles, natch), hoses, and flanges. The additional trick for teflon lined features is a outer flaring at each end of an object, either as a surface offset or a merging Extrude body. I have never used teflon lined parts extensively throughout a system, but rather only where specifically needed, so I have never needed it enough to create a full Routing Specification.
I am unfamiliar with concrete lining, and greatly assume that it is significantly different from teflon in its design, representation, installation, and use.
Thanks for the help guys. Unfortunately I do use SW Routing more often than not. For simpler single spool projects I'll just model everything including the coating/lining. I'll look into creating a new pipe.sldprt and see what I can pull off. Was hoping I didn't have to, but looks like I'm going down that rabbit hole. Maybe I'll submit a request for inside lining and enhancement to the covering models
Alright so I went ahead and created a new "CML Pipe.SLDPRT" and it actually works out better than I had expected. It extrudes the outside and inside coatings exactly how I wanted and got the materials set. Now the only issue I'm having so far is penetration. If I have a branch come off, no matter the pipe size, the penetrate doesn't trim anything. It extrudes to the center and no hole is cut in the pipe. I have no clue how to even configure that as it seems to just be an automatic procedure. Any ideas?