Problem
Thermowells in steam lines are commonly used to measure steam temperatures and are vital components of plant control systems. Initial calculations based on ASME guidance suggested that some of the thermowells might be prone to flow-induced vibration (FIV). Furthermore, cracking was observed at the base of some thermowells, necessitating remedial actions to address the problem.

Solution
Employing fluid-structure interaction (FSI) simulations, which integrate finite element analysis (FEA) and computational fluid dynamics (CFD), facilitated a comprehensive evaluation of FIV in existing thermowells. This approach, recommended by JSME, enables the consideration of intricate wake interactions and the phenomenon of vortex shedding lock-in with structural modes.

Result
FSI modeling enabled the rapid assessment of remedial measures, allowing for a quick comparison of alternative design solutions and the implementation of modifications during the turnaround. This approach significantly reduced the risk of potential failures and enhanced the reliability and safety of the steam line systems.