A centrifugal compressor of barrel-type was revamped. The end-user wanted a higher flow-mass, this required the impellers be redesigned. The original riveted impellers (eye cover, blades and impeller back assembled by rivets) were replaced by impellers manufactured by a welding process. As first step, the mass, polar and transversal moments inertia were estimated for each new welded impeller, it was determined a variation of less than +/- 1% with respect to the original values belonging to the riveted impellers. As a result, the natural frequencies of the new rotor also did not considerably vary. A finite element analysis was performed to determine the stress distribution in the welded impellers. Also, recommendations were made to reinforce some welding zones where stress concentration was the highest.