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What is welding sequence? The so-called welding sequence refers to, in a welded structure, which part is welded first and which part later; in other words, it determines the order in which each weld is carried out. What is the impact of improper welding sequence selection on welding quality? An improper selection of welding sequence has the following effects on welding quality: (1) The welding sequence directly affects the stress and deformation of the welded parts; an inappropriate choice can result in excessive deformation or internal stress in these parts, which not only reduces their quality but may also lead to their rejection in severe cases. (2) An improper selection of the assembly and welding sequence often leads to difficulties in welding the welds in certain areas; WeChat official account: Weld King, or even makes welding completely impossible. It severely reduces the strength of the welded structure, or the requirements regarding airtightness. (3) If the welding sequence of stainless steel welded structures is not chosen properly, the welds that are in contact with corrosive media may suffer from intergranular corrosion as a result of the heat generated by subsequent welds after welding, thereby reducing the corrosion resistance of the welded parts. How is the welding sequence generally chosen? The basic principles for selecting the welding sequence are as follows: (1) From the perspective of assembly welding: The welding sequence should be determined based on the principle of avoiding any difficulties or impossibility in welding the joints. (2) From the perspective of reducing welding deformation and residual stress: 1) Weld from the center of the welded structure outwards ； 2) Weld from the thick plate direction to the thin plate direction ； 3) Weld the joints with a large shrinkage amount first (butt joints), and then weld the joints with a small shrinkage amount (lap joints, corner joints) ； 4) Weld the vertical welds first, then the horizontal welds ； 5) Parallel welds should be welded simultaneously and in the same direction as much as possible ； 6) Weld the offset short welds first, then the straight long welds.