This project was carried out for Saipem and entailed the fabrication of column blisters to strengthen and stiffen four of the existing column legs on the Scarabeo 7.  This deep water drilling rig has an intended displacement of over 38,000 tonnes and overall dimensions of 61.3m in width, 77.5m in length and 4.5m in depth.
The total project weight was 163 tonne, while the total weld perimeter was approximately 3630m.  The welding was successfully completed with a low-factor 0.17% repair rate.  Due to the size of the blisters,, each structure had to be fabricated in two separate sections in order to facilitate the abnormal load transport from Belmet’s premises to the installation site at A-Berth in Cape Town Harbour.
The material used for this fabrication project was high strength marine grade carbon steel plate, with internal stiffening consisting of locally procured structural angle section. The structures were impact tested at -20oC to meet the relevant operational specifications. Non-destructive engineering criteria for this project included 100% visual inspection; magnetic particle inspection of 100% and ultrasonic testing of 100% – the actual tolerances achieved for the steelwork ranged between 3mm and 5mm over the total blister height of 14.7m.
The project began in July 2008 and was executed over a 15 week period with labour intensity recorded at 95.3 man-hours per fabricated tonne.

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