Engineering critical assessment for a sandwich pipe field joint

Abstract

This paper seeks to apply a combination of techniques with the aim of outlining a finite element (FE) based methodology for carrying out Engineering Critical Assessment on the swaged weld for J-lay installation. The critical potential defect position during installation is identified and its severity is evaluated using the Stress Concentration Factor (SCF). Closed-form parametric equations for quantifying the geometric SCF as a function of the swaged weld dimensions are derived using large-scale parametric studies and statistical analysis for the joint under tension. The maximum allowable defect size for a swaged weld under potential installation loadings is evaluated by two proposed FE-based fracture mechanics methodologies. In the absence of tearing resistance data, the influence of the filler resin stiffness, loading type and material response on the acceptability of a defect size is studied and the conservative nature of brittle fracture design for the fracture assessment of carbon steel pipelines with significant ductility is illustrated.