I know CAESAR has issues with at least some piping code combinations - e.g. B31.3/B31.8.

But hopefully you organized your CAESAR file nodes in such a way you can identify by the number what the materials are. E.G. nodes 1-4000 = steel, nodes 4010+ = FRP.

Then you can specify in the output processor to filter based on nodes 4010+ or <4010. It requires two different reports, however.