Postprocessing in cyclindrical coordinates

I am doing a plane strain analysis of a pipe with a crack in it.

I would like to get the stress components in the cyclindridcal coordinate system (radial, hoop stress) rather than in the cartesian coordinate system (x & y stress components).

There seems to be do obvcious way of doing this.

Is there anyone who can suggest something?

Thanks,
--
Arthur Rupel