An improved closed-form residual stress estimation method for girth welds in thin-walled pipe components

• An improved closed-form residual stress estimation method is presented for girth-welded thin-wall pipes for supporting structural integrity evaluation. • The method incorporates a novel treatment method for considering thin wall effects on heat dissipation and its effects on plastic zone size . • The plastic zone size can now be estimated in a thermo-mechanically coupled manner in closed form . • A significant improvement in both residual stress and distortion estimation has been shown by comparing with the state-of-the-art solutions in the literature. A reliable residual stress estimation is required for performing fracture mechanics-based structural integrity (or fitness-for-service) evaluations of pressure vessels and pipe components. Recent developments in closed-form estimation methods have shown significant potential for avoiding complex, case-by-case thermo-mechanical finite element simulations. However, for thin-walled pipes, recent studies have shown that existing methods yield inconsistent residual stress estimations. This study presents an improved closed-form residual estimation method by incorporating: (1) finite wall thickness effects on heat dissipation in the analytical estimation of maximum temperature distribution, and (2) an analytical estimation of the plastic zone boundary through a thermo-mechanically coupled formulation enabled by thin-shell theory. The improved method is validated against detailed time-history-based thermo-mechanical finite element models, with two demonstration cases highlighting its improvements. The presented method offers a physically consistent and efficient analytical solution for residual stress estimation in thin-walled pipe components.