Application of narrow-gap GTA welding process to the welding of large type stainless steel nuclear pressure vessels

Stainless steel pressure vessels for nuclear power plants are becoming increasingly larger in size and the conventional flat position welding process is now considered to be unsuitable for their welding; for example, it requires a large number of reinforcing materials to prevent deformation of the vessels by their tares and makes manufacturing procedures more and more complicated. A conceivable method to solve this problem is the introduction of vertical position welding process. This paper presents a newly developed Narrow-Gap GTA Welding Process with hot filler wire for the horizontal and vertical position welding of large type 50 mm-thick austenitic stainless steel nuclear pressure vessels. (author)