can carbon steel tubes in titanium cladded carbon steel tube sheet (the cladding is on both sides of the tube sheet)with crude in tube side and naphtha in shell side create a galvanic cell and corrode?
Well I bet there's some water contamination. While the cladding is solid there is no way of galvanic corrosion as there is there is no electrolyte (water) conductive connection between the metals.
Naptha or crude is not a good electrolyte and hence galvanci corrosion may not be a concern. Again, in my opinion, Titanium will quickly polarized and lead to further minimization of galvanic attack on iron if at all a risk is there. Hence, carbon steel tubes can be safely connected with titanium clad tube sheet in naptha or crude service.
Actually the greater risk is of minor corrosion of the steel resulting in hydrogen embrittlement of the Titanium, but as roker said this is fully clad steel so there is only risk of corrosion due to joints and only then if the Titanium cladding is not metallurgically bonded to the Steel.