Control of Welding Deformation

PART 01                                                                                                                                                               

1. When assembling components or composite components, connecting parts, and welding parts onto components, the processes and sequences adopted should minimize the deformation and shrinkage of the final components.                                        PART 02                                                                                                                                                               

2. Based on the arrangement of welds on the components, the following requirements can be followed to control deformation through a reasonable welding sequence:                                                          

For butt joints, T-joints, and cross joints, when the workpiece placement conditions permit or it is easy to turn over, bilateral symmetric welding is preferred; for components with symmetric cross-sections, welding should be symmetric with respect to the neutral axis of the component; for nodes with symmetric connecting members, welding should be symmetric with respect to the node axis and carried out simultaneously.                                                                                                                    

For asymmetric double-sided groove welds, advisable to weld the deep groove side first, then fill the shallow groove side, and finally complete the weld on the deep groove side. For extra-thick plates, the number of rotating symmetric welding cycles should be increased.                                  

 For long welds, the back-step welding method or simultaneous use of multi-person symmetric welding method is recommended.                                                                                                                  

Skip welding method should be adopted to avoid local heat concentration on the workpiece.            

PART 03                                                                                                                                                                

3. When assembling and welding components, joints with larger expected shrinkage should be welded first, followed by joints with smaller expected shrinkage. Joints should be welded under the least restrained conditions possible.                                             

 PART 04                                                                                                                                                        

4. For joints with large expected shrinkage or angular deformation, the values of welding shrinkage and angular deformation can be estimated through calculation. Before formal welding, methods such as reserving welding shrinkage allowance or pre-setting reverse deformation can be used to control shrinkage and deformation.                                                                                                     

PART 05                                                                                                                                                       

5. For each component of a composite component, splicing be completed before welding the component to other components; for composite components composed of multiple components, partial assembly welding should be adopted, and deformation should be corrected separately before proceeding with final assembly welding to reduce component deformation.                                

PART 06                                                                                                                                                          

6. For components with irregular cross-sections where the weld distribution is significantly asymmetric with respect to the neutral axis of the component, under the condition of meeting design calculation requirements, methods such as increasing or decreasing the filled weld area or using compensating heating can be adopted to balance the heat on the component and reduce deformation.                                                                                                                                                

【Explanation】The main purpose of welding deformation control in 1～6 is to ensure the dimensions required for components or structures. However, sometimes controlling welding deformation may simultaneously increase welding stress and the tendency for welding cracks. Reasonable process measures, welding sequences, and heat balance methods should be adopted to reduce or balance welding deformation, avoiding the use of rigid fixation or forced measures to control deformation. Some methods provided in this code are suMMAries of practical experience. Reasonable adoption according to actual structural conditions is effective for controlling welding component deformation.