Fluid–structure-Interaction Analysis for Welded Pipes With Flow-Accelerated Corrosion Wall Thinning

Abstract

The flow-accelerated corrosion (FAC) entrance effect results in enhanced wall thinning immediately downstream of a weld if the weld connects an upstream FAC-resistant material with a downstream less resistant material. The weld regions, especially those with local repairs, are susceptible to cracking due to the high residual stresses induced by fabrication. The combined effects of the FAC entrance effect and high stresses at a weld might compromise the structural integrity of the piping and lead to a failure. Weld degradation by FAC entrance effect has been observed at nuclear and fossil power plants. This paper describes an application using fluid–structure-interaction (FSI) modelling to study the combined effects of FAC wall thinning, weld residual stresses, and in-service loads on welded structures. Simplified cases analyzed were based on CANDU outlet feeder conditions. The analysis includes the flow and mass transfer modelling of the FAC entrance effect using computational fluid dynamics (CFD) and nonlinear structural analyses of the welded structures with wall thinning and an assumed weld residual stress and strain distribution. The FSI analyses were performed using ANSYS Workbench, an integrated platform that enables the coupling of CFD and structural analysis solutions. The obtained results show that the combination of FAC, weld residual stresses, in-service loads (including the internal pressure) and (or) extreme loads could cause high stresses and affect the integrity of the welded pipes. The present work demonstrated that the FSI modelling can be used as an effective approach to assess the integrity of welded structures.

Combined residual stresses and fluid-structure interaction finite element analysis on bent pipes

“…In FSI simulation and analysis, a transfer of momentum and forces between a pipeline and fluid are taken into consideration [12,13]. [14] Demonstrated that an FSI analysis could be used to study the integrity of a welded pipe that experienced a flow-accelerated corrosion wall thinning. The FEA considered the temperature effect on RS from the welding process, the flow and mass transfer on a pipe and wall thinning [14].…”

“…[14] Demonstrated that an FSI analysis could be used to study the integrity of a welded pipe that experienced a flow-accelerated corrosion wall thinning. The FEA considered the temperature effect on RS from the welding process, the flow and mass transfer on a pipe and wall thinning [14]. Whilst [15], have studied the influence of entrapped fluid and RS from a fused filament fabrication (FFF) process on impact behaviours of cylindrical nylon specimens [15].…”