What is welding sequence

The so-called welding sequence refers to the welding order of which part to weld first and which part to weld later in the welding structure, or which weld seam to weld first and which weld seam to weld later, that is, the welding sequence of each weld seam.

What impact does improper selection of welding sequence have on welding quality?

(1) The welding sequence directly affects the stress and deformation of the welded parts. Improper selection can cause excessive deformation or internal stress in the welded parts, which not only reduces the quality of the welded parts but can also lead to their scrapping in severe cases.

(2) Improper selection of assembly welding sequence often results in difficulty or even complete inability to weld certain positions of the weld seam. Severely reduce the strength or airtightness requirements of welded structures.

(3) If the welding sequence of stainless steel welded structures is not selected properly, the working weld that comes into contact with corrosive media will be subjected to intergranular corrosion after welding due to the thermal effect of the subsequent weld, which will reduce the corrosion resistance of the welded parts.

How to choose the welding sequence in general?

(1) From the perspective of assembly welding, the welding sequence should be considered based on the principle of not causing welding difficulties and not being able to weld the weld seam.

(2) From the perspective of reducing welding deformation and residual stress:

1) Weld outward from the center of the welded structure;

2) Welding from thick plate direction to thin plate direction;

3) First weld the joints with large shrinkage (butt joints), and then weld the joints with small shrinkage (lap joints, corner joints);

4) First weld the vertical weld seam, then weld the flat weld seam;

5) Parallel welds should be welded in the same direction as much as possible at the same time;

6) First weld the staggered short welds, then weld the straight long welds.