Reduction of welding residual stress in the head-cylinder joint of a large rectifying tower by finite element method and experimental study

The welding residual stresses (WRS) in a cracked head-cylinder joint of a large rectifying tower were studied by finite element method (FEM) and experimental study. The effects of welding layer sequence, cover welding direction and weld reinforcement have been fully studied. The results showed that the stress concentration and plastic strain accumulation caused by unreasonable welding process and structural discontinuity are the main reasons of cracking. Furthermore, the order of welding layers has a significant influence on the distribution of axial stress: the inside and outside alternating welding process is superior to non-alternating welding process. The direction of cover welding markedly influences the hoop stress: the location of maximum stress is related to the welding start-end position. Besides, the removal of weld reinforcement after welding helps to release subsurface tensile stress and solve the stress concentration problem.

Automated summary

The study investigates the welding residual stresses in a cracked head-cylinder joint of a large rectifying tower. Factors such as welding layer sequence, cover welding direction, and weld reinforcement were found to have significant effects on stress distribution. Unreasonable welding processes and structural discontinuities were identified as the main reasons for cracking, while proper welding techniques and sequences can alleviate stress concentration issues.