The banana deflection itself could be considered a one-time deflection and could be construed to have a higher allowable.

In such cases, I have treated them all as regular allowables with new piping to be on the safe side, but my settlement values were in the 4 inch range, which I'm given to understand that coke drums experiencing banana effects are much higher.

I would also give special considerations at adjacent shoe locations. If the pipe is kinking at that location, you might want to have a shoe design that's less likely to puncture the pipe.