Transmediterranean Pipelines Repair

On December, 19th 2008 major damage occurred at two pipelines of the Transmediterranean Pipeline System, which is made up of 5 pipelines, connecting Cap Bon in Tunisia to Mazara del Vallo in Sicily (Italy). A 110,000 tonnes tanker crossed the pipelines' route with one of her anchors dragging on the seabed: the 12 tonnes anchor managed to skip the first line met (causing only minor damage) but then one 26" line was completely severed and the following 20" one was badly bent and displaced more than 40 m from its route before the chain snapped leaving the remaining lines safe. The paper describes the activities carried out by Saipem S.p.A. for Transmediterranean Pipeline Company Ltd, the owner of the lines, in order to quickly restore the production. These activities included: the emergency reaction, the surveys, the engineering, the preparatory works both offshore (trenching and rock dumping) and onshore (temporary air compression stations at both land terminals) and the actual repair operations carried out by a lay vessel. On August, 3th 2009 the repairs were successfully completed and the re-commissioning was carried out such that regular production could re-start 1st October. The above water tie-in method was selected and used for the repairs: this proved the best option thanks to the relatively limited water depth of the event (approximately 70 m) and the availability of the lay barge in the area. These favourable circumstances, together with a significant organizational and management effort, were essential factors to succeed in limiting the duration of the repair operations and, correspondingly, the production down time. In fact, the lesson learnt from this experience is that, in other circumstances, a much longer time would be required unless the requirements for a repair are tackled in advance making ready the equipment and the organisation dedicated to the repair service