Ultrasonic Guided Wave-Based NDT of Hydrogen-Loaded Pipelines

ongoing

Hydrogen is seen as secure, clean and inexpensive energy of the future. To this aim, the European union has laid out strategies for large-scale production and deployment of hydrogen in the future. This translates to the most economical way of transmission of hydrogen through existing natural gas pipelines. However, one of the serious issues that can present a setback to this ambitious project is the failure of pipelines due to defects. One such less-addressed/hard-to-detect failure mechanism called Hydrogen Induced Cracks (HICs) is considered for the proposed work. In order to detect HICs in hydrogen-loaded gas transmission pipelines, an ultrasonic guided wave (UGW) based NDT technique will be developed. Towards this, a torsional guided wave mode will be optimized for its frequency from the perspective of defects (HICs) in pipe segments using the Scaled Boundary Finite Element Method (SBFEM) simulation tool available at BAM. An array of shear mode piezo-crystals for the optimized frequency will be used in the generation of the torsional mode. Towards UGW based testing, pipe segments with actual HICs will be prepared at hydrogen test rig at BAM under the guidance of BAM’s material scientists. Additionally, pipe segments with artificial notches simulating HICs will also be prepared. Further, Laser-based measurements will be carried out to map the wave fields around the crack to understand the physics of wave-defect interaction. Further, the effect of operational conditions of a pipeline such as pressure and temperature on torsional mode will be studied using both experiments and simulation. Overall, the project will involve both simulation and experiments to gain deeper understanding of the problem. Emphasis is also given on the validation of simulation results for the smooth progress of the project. Furthermore, ultrasonic phased array testing will also be carried out to successfully validate the UGW measurements pertaining to defects and to localize and size them.