Automatic girth welder, or can be called automatic tank welding machine, it take the construction eneironment into consideration, and equip USA Miller welding power,which can work under severe atmosphere, so as to keep the stability of welding. In design, we considered the welding requirements of possible large tank.so this machine can be upgraded by performed relative connnection,so it can enlarge equipment welding size and avoid overlaping investments.it can realize automatic welding for all girth seam and improve construction effeciency.It also have advantage of high operating factors.