Norway: Several Design Weaknesses Found at Gjoa Semi-Sub Rig

In connection with the completion of the semi-submersible Gjøa facility, several design weaknesses linked to ballasting and floating stability were found.

The Petroleum Safety Authority (PSA) has now sent circular letters with information about this to companies responsible for the operation of semi-submersible floating facilities on the Norwegian shelf.

Statoil has also completed an assessment of the same factors for their own semi-submersible production facilities.

The problems with stability and ballasting were discovered just before the Gjøa facility was towed to the field. One case led to minor heeling of the platform following a short circuit.

The other case was linked to deficient stability calculations in a potential damaged condition.

The weaknesses could, under certain circumstances, have resulted in serious consequences, but were corrected before the Gjøa facility was towed out.

We believe that it is important to share information about these conditions with other players in the industry. To this end, we have sent out such information to all companies that operate semi-submersible mobile facilities on the Norwegian shelf, so that they will have the opportunity to ensure that there are no similar faults on their facilities.

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Source: Ptil,September 6, 2010,