Once the tank is lifted using our jacking equipment, and a new course (shell ring) is placed, vertical and horizontal welds are completed either manually or using an automatic welding machine. Root welding can be done either manually or using a few attachments of our Automatic Girth Welding head using backing strip material. After external welding, hydraulic jacks are released from the tank shell plate, lifting lugs and fend-off lugs are removed, and with the same hydraulic power pack (which is used for lifting jacks), all trestles box retracts away from the tank shell, to allow for space for the use of the Astha Group of company SAW single side AGW for internal welding, the welding process is very fast. After the internal horizontal welding is done, the trestles box is moved back by the same power pack to its original vertical position, ready to lift the next shell course