Back to search

PETROMAKS2-Stort program petroleum

Hydrogen-induced degradation of offshore steels in ageing infrastructure - models for prevention and prediction (HIPP)

Alternative title: Hydrogenindusert skade i aldrende offshore stålkonstruksjoner - modeller for reduksjon og prediksjon

Awarded: NOK 17.4 mill.

As the industry is pushing for life extension of existing oil and gas fields, they have to cope with an ageing infrastructure. Aging steel structures needs careful considerations with respect to degradation mechanisms as corrosion, fatigue and hydrogen embrittlement. Management of ageing infrastructure is essential to minimize the environmental hazard and avoid large costs due to down time and repair. Elemental hydrogen has dramatic consequences on material properties, especially by reducing the fracture toughness. Degradation by hydrogen initiates through mechanisms occurring locally, and is normally not detectable prior to the final leakage or component fracture. The final leakage or fracture happen unforeseen and may cause catastrophic failures. This may result in not only huge economic losses but also irreversible human and environmental impacts. Through the cooperation of NTNU, SINTEF and UiO, a multiscale modelling and verification framework have been developed to describe the hydrogen-induced degradation of selected materials and grain boundaries. On the experimental side, a state-of-the-art nanotechnology-based tool for characterizing the hydrogen embrittlement susceptibility using micron scale cantilever beam specimens under realistic electrochemical environmental conditions have been established in the HIPP project. With the established experimental method, the effect of hydrogen and microstructure on the mechanical properties can be investigated very locally. The experimental method also provides important verifications to the multiscale models. The modelling framework established in the HIPP project includes accurate quantum mechanical calculations of the grain boundary de-cohesion properties as a function of hydrogen concentration; molecular dynamics simulation of the deformation mechanisms and plasticity in front of a crack tip charged with hydrogen; and hydrogen-informed continuum based cohesive zone approach. With the framework developed, we are now able to predict the hydrogen-induced degradation at grain boundary both at microscale and macroscale. With respect to education, 3 PhDs will graduate from the HIPP project. It should be mentioned that in this project, ideal material systems were used to gain fundamental understandings of the complex hydrogen embrittlement phenomena. The findings and the basic understandings achieved in this research project are ready to be extended to develop practical lifetime extension procedures in the offshore industry and other areas where hydrogen embrittlement is a challenge, such as hydrogen transport and storage.

Elemental hydrogen has dramatic consequences on material properties, especially by reducing the fracture toughness. Degradation by hydrogen initiates through mechanisms on the nano-scale, and is normally not detectable prior to the final leakage or compon ent fracture. Such incidents are sudden, and sometimes catastrophic failures occur, causing not only huge economic losses, but also irreversible human and environmental impacts. This project attacks the challenge of linking modelling of fundamental mechan isms on the nano-scale with finite element methods on higher scales. On the basis of existing knowledge and expertise on atomistic simulations, embrittlement mechanisms and fracture mechanics assessment, this project will provide a scientific platform for an integrated model that can assess hydrogen induced failures in offshore steel structures. In addition, to bridge the gap towards describing realistic situations under offshore and subsea working conditions of industrial relevance, experimental validati on is included as an integral part of the project. The project team consists of three complementary groups (NTNU Nanomechanical Lab, SINTEF Materials and Nanotechnology, and University of Oslo), of skilled and experienced scientists that join their effort s in order to realize a mechanism-based integrity assessment approach.

Publications from Cristin

Funding scheme:

PETROMAKS2-Stort program petroleum