Underwater Friction Stud Welding: Evaluating Optimum Parameter Settings for Subsea Intervention Without a Shroud

Underwater friction stud welding (FRSW) uses a shroud around the stud, controlling extreme cooling rates from the surrounding water. The FRSW commonly requires integration with a remote operating vehicle (ROV) or diving system when it is remotely operated in subsea deployed interventions. A hydraulic FRSW unit has been designed and fabricated to perform FRSW without a shroud via a ROV. Use of the FRSW unit without a shroud indicated significant challenges in welding studs underwater. Hence, an experimental study was initiated to investigate the optimum FRSW parameter values minimizing the inherent challenges. The experimental study was performed to estimate the optimum parameter settings for welding a grade 8.8 bolt on an S235 structural steel plate. This manuscript discusses the experimental approach, results and conclusions reached in the parameter evaluation, estimation and experimentation.