When the big pipe（φ133×10 mm） is fixed and butted at 45 degrees

the welding position of the pipe is between the horizontal fixed pipe and vertical fixed pipe. The welding is always carried out in the inclined position of pipe

which increase the operative difficulties. When using hybird gas solid wire with low current

the shallow penetration will easily form inclusions and dot defects

and the form is difficult to control when the current is too high. The experimental study is conducted for how to improve the appearance and internal quality

the welding specifications

angles and swing methods

interpass arrangement and welding skills are emphasized

which plays a guiding role in training teaching and production practice.