This is a self-propelled welding equipment primarily developed for on-site erection of large storage tanks, silos, blast furnaces and similar cylindrical objects. It is designed to travel on the top edge of the tank shell. For weather protection the cabin can be covered by curtains. The cabin of machine is equipped with step ladders and a joining bridge at the top to facilitate for the operators to climb onboard. The bridge also has guard rails for the safety of the operators.