See attachment!

I've read over and over that seismic analysis shall not account for friction in its solution. I agree. Where I'm caught up is making sure my load cases are set up properly to get me there. Is it as simple as making the friction multiplier on cases L7 and L8 "0.0"?

This confuses me if so because in L16, L17, L22, and L23 they use the standard operating and sustained cases with full "1.0" friction. Would I need to create a separate normal operating case and sustained case with their own "0.0" multiplier to use within the seismic L16, L17, L22, and L23 load cases?

Thanks for any feedback!!

1. Unless you have very symmetrical pipe, you'll also need two additional load cases with -U1 and -U2.
2. Yes, L7 and 8 should have their friction multiplier set to 0. There's no credit from friction to prevent your pipe from sliding everywhere. Use guides, instead.
3. No, you should not generally set friction multipliers to 0 for the others. Eliminating the the friction would reduce (generally) the difference between the two states, and therefore reduce the calculated stresses.
However, if you come across a configuration where friction somehow helps your system to pass its expansion cases, you're not supposed to be taking credit for friction for this purpose. I'll note that I've never seen anyone run things in duplication without friction to verify this.

joeseagle,

The original requirement came from structural codes.

For example in ASCE 7 "Friction resulting from gravity loads shall not be considered to provide resistance to seismic forces.". However one may note that the requirement is not "ignore friction in seismic analysis".
Trying to explain where the difference is... for a structural engineering point of view, what is analyzed is not pipes but the supporting structure (either a pipe-rack or an equipment structure with piping levels), and piping is considered as masses accelerating horizontally during seismic event. Consequently, most of structural engineers will ask for Mass of the Structure + Piping&Equipment in operation to calculate the total Static Equivalent Force "V", also called Base Shear.

Ignoring friction effects (and taking credit only to stress report) would end in having no participation of piping mass in points of structure where piping rest on; under seismic event, piping will move with no horizontal load transfer to structure. However, the structural engineers will consider mass where the rest is, but will add also the results of "non-friction" stress analysis in points where only guides and axial supports take the seismic loads. In my interpretation that means the structural procedure is not an exact one and is conservative enough, as the structural code intended. I don't think there is a need to be improved as you suggested.

As for the piping calculation ignoring friction, I would consider a B31E one as more appropriate, unfortunately this is not the way required by piping codes.