Stainless Steel Tank is made mostly on the rotating table. The floor is placed first, then the wall is placed over and supported by the overhead crane and small tacking welds with TIG are placed, to hold the floor and the wall. Next the roof is placed onto the wall and small tacking welds with TIG are placed to hold in place the roof.
Now the welder will continue to rotate the Stainless Steel Tank and he will add more and more small tacking welds with TIG. His job is to slowly make the gap between the tacking welds, get less and less. When the gaps in the weld are 25mm each, he can MIG weld the top and the bottom to the wall.
This is done when the welder is seated and the Stainless Steel Tank is slowly rotated at the exact speed. The MIG welder is supported next to the welder hand the hand piece is held also. The welder will only need to press the trigger and swivel the tip closer to the welding pieces. Now it is automatic because the Stainless Steel Tank will rotate and the welder controls the MIG hand piece. Inside the tank there is another man who is purging the weld.
when a welder is MIG or TIG welding such things as the floor, roof, butterfly valves onto outlet tubes and reducers, it is necessary to apply the same welding gas to the inside of the welding area to remove (purge) any oxygen (air) from the hot area inside. If this is not done the hot metal will oxidize and the surface quality is very poor. With purging of the weld, the weld quality inside is very good and will not need to be repaired.
Purging, covering the weld root and adjacent parent material with a shielding gas in order to protect the penetration bead from becoming contaminated by coming into contact with atmospheric gases during and after welding; temper colors can be prevented or greatly reduced from the outset. Purging is an economical, clean and environmentally friendly method to present a good welding appearance.