We bead tubes for one reason, to transfer the heat from the tube end into the tube sheet—a dissipation of heat. Usually, at the first pass, otherwise known as the hot pass, tubes welded will transfer the heat to the tube sheet. Temperatures on the hot pass can be 1800-1900 degrees. If not welded cracking or burn back would occur. This in turn would cause the tube joint to fail. On the next pass, the tubes rolled and beaded pass the heat back to the sheet. The heat then transfers to the larger mass, albeit the tube sheet.

To achieve formed tube joints with beads we must follow certain specific requirements. This applies to both procedures, manual beading or using combination beading expanders. A required protrusion, or stick-out, of the tube from the tube sheet to form the bead. For the combination expander, this protrusion, listed as found in the specifications.