Abstract: A method and apparatus for appropriately deforming the tube extensions projecting beyond the tube sheet is disclosed. The excess extension material is rolled backwardly toward the tube sheet and slit to prevent catastrophic failure of the extension such that the tube extensions are all configured to extend equidistantly from the tube sheet notwithstanding the fact that they extended various distances depending upon the irregularities of the expansion process. The tooling includes a cylindrical tool having portions for rolling material back towards the tube sheet and spaced teeth for slitting the material to relieve any potential for catastrophic failure.