Burst testing of internal sharp defect in hydrogen – conditioning investigation

This project will investigate the effect of hydrogen exposure and conditioning on the failure behaviour of internal sharp defects in pipeline steels. The work builds on testing previously undertaken as part of the LTS Futures programme and NIA_SGN0070, where full-scale burst testing indicated that hydrogen exposure may influence the failure pressure associated with internal crack-like defects. However, the available dataset remains limited, and some results have shown inconsistencies, suggesting that hydrogen conditioning and exposure history may significantly affect material response.

The project will undertake additional full-scale burst testing on vessels fabricated from representative pipeline material containing machined internal sharp defects. The vessels will be subjected to controlled hydrogen conditioning prior to burst testing to evaluate the effect of hydrogen diffusion and retention on fracture behaviour and failure pressure.

Complementary laboratory-scale mechanical testing and fractographic analysis will also be performed to characterise material properties and failure mechanisms. The results will support pipeline integrity assessments and the safe repurposing of the UK Local Transmission System (LTS) for hydrogen transport.