A study of the residual stress and deformation in the welding between half-pipe jacket and shell

Half-pipe jacketed vessels are widely used as the heating or cooling structure in the chemical industries. But the leakage of the welding joint between the jacket and cylinder is a big problem, which is greatly affected by the residual stress and deformation. This paper presents a finite element analysis of residual stress and deformation induced by welding half-pipe jacket to shell, and the effects of heat input, cooling inside the shell and welding sequence on residual stress have been discussed. It is found that large longitudinal stress is generated in the weld metal. Due to the local weld heating, the jacket and shell become un-circle. A wave shape of stress along the circumferential of shell is generated. With the heat input increase, the residual stress and ellipticity increase linearly. On the premise of entire penetration welding, smaller heat input should be used to avoid too big deformation. Filling the shell with cooling water can decrease the residual stress and ellipticity during the welding, and welding the two joints of one jacket simultaneously is also available, which provides a reference for the welding of half-pipe jacket.