Study of welding process at deep waters (high chamber pressure)
Requirements and possibilities for heating (including preheating)
Weld modelling, with different joint configurations, including wall thicknesses, welding parameters, cooling conditions, restraint intensities and residual stresses
Modelling of hydrogen pick up and diffusion during welding and possible subsequent post heating
Structural integrity and acceptance criteria. The hot tapping is considered to impose heavy restraining with imminent risk of cracking during or after welding. Therefore, modelling is regarded very useful, with model validations based on experimental measurements of simpler geometries at 1 bar. Finite element models will also be developed including heat distributions in various geometries, transformation behaviour, hardness, residual stresses, hydrogen pick up and diffusion and cold cracking susceptibility. The involvement of PhD studies allows more detailed study of selected areas in hyperbaric welding. This is, in fact, the first possibility to educate PhD students in Norway related to the area of hyperbaric welding.
