A full-field residual stress estimation scheme for fitness-for-service assessment of pipe girth welds: Part II – A shell theory based implementation

• A shell theory based two-part assembly model is developed for generalizing residual stress distributions.
• A full-field estimation of through-thickness residual stress profiles can be achieved.
• The proposed estimation scheme offers both consistency and mechanics basis in residual stress profile generation.
• An estimation scheme for welding-induced plastic zone size is proposed and validated.
• The shell theory based estimation scheme can also provide a reasonable estimate on distortion in radial direction.

With the two key controlling parameters identified and their effectiveness demonstrated in Part I of this study series for constructing a continuous residual stress profile at weld region, a classical shell theory based model is proposed in this paper (Part II) for describing through-thickness residual stress distributions of both axial and hoop components at any axial location beyond weld region. The shell theory based model is analytically constructed through an assembly of two parts: One represents weld region and the other represents the remaining component section away from weld. The final assembly of the two parts leads to a closed form solution to both axial and hoop residual stress components as a function of axial distance from weld toe position. The effectiveness of the full-field residual stress estimation scheme is demonstrated by comparing with a series of finite element modeling results over a broad range of pipe weld geometries and welding conditions. The present development should provide a consistent and effective means for estimating through-thickness residual stress profile as a continuous function of pipe geometry, welding heat input, as well as material characteristics.