What are the welding methods of double shielded welding?

(1) left welding method (right → left)

(2) Right welding method (left → right)

(3) Method of gun transportation

(4) The flat angle welding does not swing or slightly swings.

(5) The vertical angle is welded upwards, and a triangular gun is used.

(6) Welding torch transition: stay at both sides of the molten pool and transition at 1/3 in front of the molten pool.

(7) Angle of welding torch: perpendicular to the welding seam, making an angle of 80-90 with the conveying direction of welding torch.

(8) Test plate: the gap is 2.0-2.5 mm, and the arc starting point is slightly smaller than the arc closing point. No blunt edge, reverse deformation 1.

What is the principle of the second welding?