Manufacturing and welding assembly of the vacuum vessel on JT-60SA

•JT-60SA VV was manufactured as a torus with design offset value of weld shrinkage.•Installation resulted in locally over 10 mm radial error deviated from design value.•Dimensional clearance was confirmed not to cause any interference.•Design concept to reduce safety factor and welding amount was reported. The JT-60SA Vacuum Vessel (VV) was manufactured as the 10 sectors split in the factory and these sectors were weld-assembled as the 360-degree torus with the design offset value of the weld shrinkage. The dimensions as the 10 m scale torus were well controlled regardless of the thin wall thickness of 18 mm and a large amount of welding line due to the double wall structure and 72 port penetrations. The final VV 20-degree sector was installed into the 340-degree sector of the tokamak with the TF coil and the VV Thermal Shield, and the VV was weld-jointed as a torus. This paper reports the design concept to reduce the safety factor and welding amount to achieve the dimension specified, and the result of the VV manufacturing.