Abstract: A weld joint round tool. A heavy walled central mounting ring has a mounting plate joined thereto that forms the foundational structure to which all of the moving parts are anchored. Rounding/clamping is performed by twenty-four simultaneously activated shoes that are connected by linkage arms to a central actuator ring. The shoes are expanded or retracted by rotating the actuator ring, which in turn pushes or pulls on each linkage. The ring is rotated by an AC servo motor linked to a gear reducer, the output of which drives a stationary pinion gear to move a rack mounted on the actuator ring. The weld joint round tool is mounted on the end of a cantilevered mandrel structure, which is inserted into the cylinders to be welded. Once the tool is positioned at the joint between the two cylinders, the shoes are expanded to clamp the inner diameter of the two cylinders so that welding can take place.