Abstract: In a heat exchange apparatus, a tube holding means for providing an improved tube joint between each tube end and its tubesheet in which each tube end is expanded to become an interference fit in one of the tube containing apertures of the tubesheet. The defining surface of each tube containing aperture includes novel metal collecting portions which act to prevent a linear extension of the tube and thereby reduce undesirable stress concentrations in the tube after expansion. The forming apparatus includes a tapered driving mandrel and a plurality of oppositely tapered rolls carried in a roll cage circumferentially around the mandrel for radial movement by the mandrel against the surface defining the tube containing aperture. In forming the tube holding means the metal collecting portions are roll formed and the defining surface of the tube containing aperture is worked to improve its bonding characteristics.