Since 2000, there have been two incidents on the Norwegian Continental Shelf of horizontal wave impacts on the superstructure of semi-submersible facilities. We have also received reports of a total of 27 incidents where waves have hit the underside of the deck on semi-submersible facilities and tension leg platforms.
Objective
With this audit we wanted to gain an overview of Engie's management of Gjøa and in particular factors relating to the danger of wave loads on the superstructure and the consequences of such loads.
The purpose was to determine the status of Engie's follow-up for protecting the Gjøa facility from waves on deck. We were also seeking an insight into Engie's routines and criteria if measures are required to secure the facilities in certain sea states.
The objective was to raise awareness of the problems relating to airgaps and to gain an insight into whether necessary measures have been implemented and to verify if the facilities are robust enough to withstand wave impact incidents.
Result
No non-conformities were identified.
One improvement point was identified concerning analysis assumptions and their conformity with present day knowledge of the issue.
Engie has been given a deadline of 20 January 2018 to report on how the improvement point will be addressed.